JP3100526B2 - Switching power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching power supply apparatus which receives an alternating current such as a commercial alternating current power supply.

[0002]

2. Description of the Related Art In recent years, switching power supply devices have been widely used as power supply circuits for various electronic devices because of their highly efficient power conversion characteristics. However, since many of them have a capacitor input type input rectifier circuit, the power factor is poor, and the harmonic components contained in the input current cause other electronic devices to fail.

FIG. 29 shows a conventional switching power supply device. In FIG. 29, 1 is an input AC power supply, 2 is an input filter capacitor, which is connected to both ends of the input AC power supply 1. Reference numeral 3 denotes a full-wave rectifier circuit, which includes diodes 31 to 34. Reference numeral 4 denotes a smoothing capacitor, which constitutes a capacitor input type input rectifier circuit for rectifying and smoothing the AC input voltage of the input AC power supply 1 with the full-wave rectifier circuit 3 and the smoothing capacitor 4. Reference numeral 8 denotes a transformer, which includes a primary winding 81 and a secondary winding 8.
And 2. Reference numeral 9 denotes a switch element, and a series circuit of the primary winding 81 and the switch element 9 is connected to both ends of the smoothing capacitor 4. Reference numeral 20 denotes a rectifying / smoothing circuit,
2, a secondary winding 82 composed of a choke coil 23 and a capacitor 24,
Rectified and smoothed, and supplies an output DC voltage to the load 25. A control circuit 40 controls the on / off ratio of the switch element 9 so as to stabilize the output DC voltage supplied to the load 25.

FIG. 30 shows an input waveform of the switching power supply device configured as described above. With respect to the sine-wave AC input voltage, the full-wave rectifier circuit 3 conducts only near the peak value, and the charging current to the smoothing capacitor 4 concentrates. Therefore, the input current waveform has a peak with a short conduction period.

[0005]

However, in the above-mentioned conventional configuration, the power factor is poor, and the input current contains many harmonic components, which causes a failure in other electronic devices. .

Therefore, prior to the present invention, the present inventors set out FIG.
A switching power supply device as shown in FIG. In addition,
Components having the same functions as those in FIG. 29 will be described with the same reference numerals.

In FIG. 31, 1 is an input AC power supply, 2 is an input filter capacitor, which is connected to both ends of the input AC power supply 1. Reference numeral 3 denotes a full-wave rectifier circuit, and diodes 31 to 34 are provided.
It consists of. 4 is a smoothing capacitor, 5 is a choke coil, and one end of the choke coil 5 is connected to the positive output terminal of the full-wave rectifier circuit 3. 8 is a transformer, a primary winding 81,
It has a secondary winding 82, a tertiary winding 83 and a quaternary winding 84 connected to the other end of the choke coil 5. Reference numeral 9 denotes a switch element, and a series circuit of the primary winding 81 and the switch element 9 is connected to both ends of the smoothing capacitor 4. Reference numeral 10 denotes a diode, and a series circuit with the quaternary winding 84 is connected to both ends of the smoothing capacitor 4. Reference numeral 20 denotes a rectifying and smoothing circuit, which includes diodes 21, 22, a choke coil 23 and a capacitor 24.
And rectifies and smoothes the voltage generated in the secondary winding 82 by the on / off operation of the switch element 9, and supplies the output DC voltage to the load 25. Reference numeral 40 denotes a control circuit, and a load 25
The on / off ratio of the switch element 9 is controlled so that the output DC voltage supplied to the switch element 9 is stabilized. The voltage of the input AC power supply 1 is Vi, the voltage of the smoothing capacitor is Ec, the number of turns of the primary winding 81 is N1, the number of turns of the tertiary winding 83 is N3, and the turn ratio is N = (N3 / N1) quaternary winding 84. Is N4, N4 =
The operation will be described below for N1.

First, when the switch element 9 is turned on while the input AC power supply 1 has the polarity shown in FIG.
Generates a voltage of (N · Ec). If the voltage Vi of the input AC power supply 1 is higher than (1-N) Ec, the diodes 31 and 33 conduct, and the input AC power supply 1 → diode 31
→ choke coil 5 → tertiary winding 83 → primary winding 81 → switch element 9 → diode 33 → input AC power supply 1 or input AC power supply 1 → diode 31 → choke coil 5
→ Tertiary winding 83 → Smoothing capacitor 4 → Diode 33 →
A current flows through the route of the input AC power supply 1. Vi- (1-N) Ec is applied to the choke coil 5, and this current increases linearly with a slope proportional to Vi- (1-N) Ec.

When the switch element 9 is turned off, the input AC power supply 1 → the diode 31 → the choke coil 5 → the tertiary winding 8
A current flows through the route of 3 → smoothing capacitor 4 → diode 33 → input AC power supply 1. The choke coil 5 has Vi
− (1 + N) Ec is applied and this current decreases linearly and eventually goes to zero.

When the input AC power supply 1 is inverted from the polarity shown in FIG. 31, a diode 32 operates instead of the diode 31 and a diode 34 operates instead of the diode 33.

FIG. 32 shows operation waveforms of the respective parts when N = 1 in the above operation. 32, (a) shows the output voltage waveform of the full-wave rectifier circuit 3, and (b) shows the choke coil 5.
And (c) is an input current waveform. The current flowing through the choke coil 5 has a sawtooth waveform having a peak value proportional to the voltage of the input AC power supply 1. The input current waveform smoothed by the filter capacitor 2 has a sine wave shape substantially proportional to the input AC voltage.

If N <1, Vi- (1-N) E
When c <0, the full-wave rectifier circuit 3 does not conduct, and the input current waveform is as shown by the broken line in the figure. However, the current flowing through the choke coil 5 not only flows through the tertiary winding 83, but the induced current flows through the primary winding 81 when the switch element 9 is on, and the quaternary winding when the switch element 9 is off. Since the current also flows through the switching power supply 84, there is a problem that conduction loss is large and efficiency as a switching power supply device is low.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a switching power supply device having a high power factor, an input characteristic with a low input current harmonic component, and a higher efficiency.

[0014]

According to a first aspect of the present invention, there is provided a switching power supply device, wherein a full-wave rectifier circuit for rectifying an input AC power and one end of a primary winding is connected to a positive output terminal of the full-wave rectifier circuit. A transformer, a switch element connected to the other end of the primary winding of the transformer, a smoothing capacitor connected in parallel to a series circuit of the primary winding of the transformer and the switch element, and an input of the full-wave rectifier circuit. First and second diodes each having an anode terminal connected to each of the terminals, and a cathode terminal connected to a connection point between the primary winding of the transformer and the switch element; and a connection between the switch element and the smoothing capacitor. A choke coil connected between a point and a negative output terminal of the full-wave rectifier circuit, and a rectifying and smoothing output of a secondary winding of the transformer to supply a DC output voltage to a load. A smoothing circuit, the DC output voltage of the rectifying smoothing circuit is characterized by comprising a control circuit for controlling the on-off ratio of the switching element so as to stabilize.

[0015]

With this configuration, the route of the current flowing through the choke coil is such that when the switch element is on, the input AC power supply → the first or second diode → the switch element → the choke coil → the full-wave rectifier circuit → the input AC power supply When the switch element is off, the input AC power supply → the full-wave rectifier circuit → the smoothing capacitor → the choke coil → the full-wave rectifier circuit → the input AC power supply, and the winding of the transformer does not intervene in the current route.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the embodiments shown in FIGS. (First Embodiment) FIGS. 1 and 2 show a first embodiment.

In FIG. 1, 1 is an input AC power supply, 2 is a filter capacitor, which is connected to both ends of the input AC power supply. Reference numeral 3 denotes a full-wave rectifier circuit, which includes diodes 31 to 34 and rectifies an input AC voltage of the input AC power supply 1. 4 is a smoothing capacitor, 5 is a choke coil, and a series circuit of the smoothing capacitor 4 and the choke coil 5 is a full-wave rectifier circuit 3.
Output terminal. 61 is a first diode, 62
Is a second diode. The anode terminals of the first diode 61 and the second diode 62 are connected to the input AC power supply 1, and the cathode terminals are connected to each other. 8
Is a transformer having a primary winding 81 and a secondary winding 82.
Reference numeral 9 denotes a switch element, and a series circuit of the primary winding 81 and the switch element 9 is connected to both ends of the smoothing capacitor 4. The connection point between the primary winding 81 and the switch element 9 is connected to the cathode terminals of the first diode 61 and the second diode 62. Reference numeral 20 denotes a rectifying and smoothing circuit, which includes diodes 21, 22,
It is composed of a choke coil 23 and a capacitor 24. The rectifying / smoothing circuit 20 is connected to the secondary winding 82 and rectifies and smoothes a voltage generated in the secondary winding 82 by the on / off operation of the switch element 9. 25 is a load. A control circuit 40 controls the on / off ratio of the switch element 9 so as to stabilize the DC output voltage supplied to the load 25.

Here, the smoothing capacitor 4, transformer 8,
The part composed of the switch element 9, the rectifying and smoothing circuit 20, the load 25 and the control circuit 40 is a normal DC / DC
Since the operation is the same as that of the converter, the description is omitted.

When the switching element 9 is on while the input AC power supply 1 has the polarity shown in FIG.
Is conducted, and a current flows through the route of the input AC power supply 1 → the diode 61 → the switching element 9 → the choke coil 5 → the diode 33 → the input AC power supply 1. The voltage of the input AC power supply 1 is applied to the choke coil 5, and this current increases linearly with a slope proportional to the voltage of the input AC power supply 1.

When the switch element 9 is turned off, the diode 31 becomes conductive instead of the diode 61, and a current flows through the route of the input AC power supply 1, the diode 31, the smoothing capacitor 4, the choke coil 5, the diode 33, and the input AC power supply 1. . The difference between the voltage of the input AC power supply 1 and the voltage of the smoothing capacitor 4 is applied to the choke coil 5, and this current decreases linearly and eventually becomes zero.

When the input AC power supply 1 is inverted from the polarity shown in FIG. 1, the diode 61 is replaced by the diode 62, the diode 31 is replaced by the diode 32, and the diode 33.
Instead, the diodes 34 operate.

FIG. 2 shows the operation waveforms of the respective parts due to the repetition of such an operation. 2A shows an output voltage waveform of the full-wave rectifier circuit 3, FIG. 2B shows a current waveform flowing through the choke coil 5, and FIG. 2C shows an input current waveform. The current flowing through the choke coil 5 has a sawtooth waveform having a peak value proportional to the voltage of the input AC power supply 1. The input current waveform smoothed by the filter capacitor 2 has a sine wave shape substantially proportional to the input AC voltage.

As described above, in the first embodiment, the input current waveform is improved in the same manner as the switching power supply device shown in FIG. 31, so that the power factor can be improved and the harmonic current component can be reduced. Further, since the current of the choke coil 5 flows without passing through the transformer 8 shown in FIG. 31, the conduction loss can be reduced.

(Second Embodiment) FIGS. 3 and 4 show a second embodiment. In FIG. 3, 1 is an input AC power supply, 2 is a filter capacitor, 3 is a full-wave rectifier circuit, 4 is a smoothing capacitor, 5 is a choke coil, 9 is a switch element, 20 is a rectifying and smoothing circuit, 25 is a load, and 40 is control. Circuit. The above is the same as the configuration in FIG.

The difference from the configuration of FIG. 1 is that a transformer 8 is provided with a tertiary winding 83 having one end connected to one end of a primary winding 81, and the cathode terminals of the first and second diodes 61 and 62 are connected to the tertiary winding. 83 is connected to the other end.

The voltage of the smoothing capacitor 4 is Ec, the number of turns of the primary winding 81 is N1, and the number of turns of the tertiary winding 83 is N3.
= (N3 / N1), the operation will be described below.
First, when the input AC power supply 1 has the polarity shown in FIG. 3 and the switch element 9 is on, a voltage of N · Ec is generated in the tertiary winding 83. When the voltage Vi of the input AC power supply 1 is (1-
N) If it is larger than Ec, the diodes 61 and 33 conduct, and the input AC power supply 1 → the diode 61 → the tertiary winding 83 →
Primary winding 81 → switch element 9 → choke coil 5 → diode 33 → input AC power supply 1 and input AC power supply 1
→ Diode 61 → Tertiary winding 83 → Smoothing capacitor 4 →
A current flows through the route of the choke coil 5 → the diode 33 → the input AC power supply 1. The choke coil 5 has Vi-
(1-N) Ec is applied, and this current becomes Vi- (1-
N) It increases linearly with a slope proportional to Ec.

When the switch element 9 is turned off, the diode 31 becomes conductive instead of the diode 61, and a current flows through the route of the input AC power supply 1, the diode 31, the smoothing capacitor 4, the choke coil 5, the diode 33, and the input AC power supply 1. . Vi-Ec is applied to the choke coil 5, and this current decreases linearly and eventually becomes zero.

When the polarity of the input AC power supply 1 is reversed from that of FIG. 3, the diode 62 is used instead of the diode 61, the diodes 32 and 33 are used instead of the diode 31.
Instead, the diodes 34 operate.

In the above operation, if N = 1, the second
The operation of this embodiment is equivalent to the operation of the first embodiment. N
FIG. 4 shows the operation waveform of each part in the case of <1. 4A shows an output voltage waveform of the full-wave rectifier circuit 3, FIG. 4B shows a current waveform flowing through the choke coil 5, and FIG. 4C shows an input current waveform. When Vi− (1−N) Ec <0, the diode 61 does not conduct, an input current non-conduction period occurs, and the power factor is slightly reduced as compared with the first embodiment. However, the tertiary winding 8
3 is smaller than that of the first embodiment, and the voltage applied to the diode 61 when the switch element 9 is off is reduced.

As described above, in the second embodiment, the input current waveform is improved in the same manner as the switching power supply device shown in FIG. 31, so that the power factor can be improved and the harmonic current component can be reduced. Further, the current of the choke coil 5 is
When the switch is off, the current flows without passing through the tertiary winding 83, so that the conduction loss can be reduced as compared with the switching power supply device shown in FIG. By setting N <1, the withstand voltage of the diode 61 can be reduced as compared with the case of the first embodiment.

(Third Embodiment) FIG. 5 shows a third embodiment. 5 differs from the configuration of FIG. 1 in the structure and connection position of the choke coil 5. In this embodiment, FIG.
Is changed to a two-winding structure of a first choke coil 51 and a second choke coil 52, and the first choke coil 51 and the second choke coil 52 are electromagnetically coupled to each other. .

The first choke coil 51 is connected between the connection point between the smoothing capacitor 4 and the primary winding 81 and the positive output terminal of the full-wave rectifier circuit 3. Second choke coil 5
2 is connected between the cathode terminals of the first and second diodes 61 and 62 and the connection point between the primary winding 81 and the switch element 9.

The operation of the thus configured switching power supply will be described. First, when the input AC power supply 1 has the polarity shown in FIG. 5 and the switch element 9 is on, the diodes 61 and 33 conduct, and the input AC power supply 1 → the diode 61 → the second choke coil 52 → the switch element 9 → A current flows through a route from the diode 33 to the input AC power supply 1. The voltage of the input AC power supply 1 is applied to the second choke coil 52, and this current increases linearly with a slope proportional to the voltage of the input AC power supply 1.

When the switch element 9 is turned off, the diode 31 becomes conductive instead of the diode 61, and the input AC power supply 1 → the diode 31 → the first choke coil 51 → the smoothing capacitor 4 → the diode 33 → the input AC power supply 1 Electric current flows. The voltage difference between the input AC power supply 1 and the smoothing capacitor 4 is applied to the first choke coil 51,
This current decreases linearly and eventually goes to zero.

When the polarity of the input AC power supply 1 is reversed from that of FIG. 5, the diode 61 is replaced by the diode 62, the diode 31 is replaced by the diode 32, and the diode 33.
Instead, the diodes 34 operate.

By repeating such an operation,
The current flowing through the second choke coils 51 and 52 has a sawtooth waveform having a peak value proportional to the voltage of the input AC power supply 1. The input current waveform smoothed by the filter capacitor 2 has a sine wave shape substantially proportional to the input AC voltage.

As described above, in the third embodiment, the operation is the same as that of the configuration shown in FIG. 1. By improving the input current waveform, the power factor can be improved and the harmonic current component can be reduced. Since the currents of the first and second choke coils 51 and 52 flow without passing through the transformer 8, the conduction loss can be reduced as compared with the switching power supply shown in FIG. In addition, since the choke coil 5 is located on the positive electrode side as compared with the configuration of FIG. Erroneous operation is less likely to occur.

(Fourth Embodiment) FIG. 6 shows a fourth embodiment. 6 is different from the configuration of FIG.
A tertiary winding 83 connected to one end of the primary winding 81 is provided, and the second choke coil 52 is connected to the cathode terminals of the first and second diodes 61 and 62 and the other end of the tertiary winding 83. Is a point.

The voltage of the smoothing capacitor 4 is Ec, the number of turns of the primary winding 81 is N1, and the number of turns of the tertiary winding 83 is N3.
= N3 / N1. First, when the input AC power supply 1 is in the polarity period of FIG.
Is ON, a voltage of N · Ec is generated in the tertiary winding 83. If the voltage Vi of the input AC power supply 1 is higher than (1-N) Ec, the diodes 61 and 33 conduct, and the input AC power supply 1 → the diode 61 → the second choke coil 52 → the tertiary winding 83 → the primary winding 81. → switch element 9 → diode 33 → input AC power supply 1 and input AC power supply 1 → diode 61 → second choke coil 52 → tertiary winding 83
→ smoothing capacitor 4 → diode 33 → input AC power supply 1
The current flows through the route. Vi- (1-N) Ec is applied to the second choke coil 52, and this current is Vi- (1-N) Ec.
It increases linearly with a slope proportional to (1-N) Ec.

When the switch element 9 is turned off, the diode 31 becomes conductive instead of the diode 61, and the input AC power supply 1 → the diode 31 → the first choke coil 51 → the smoothing capacitor 4 → the diode 33 → the input AC power supply 1 Electric current flows. The first choke coil 51 has Vi
-Ec is applied and this current decreases linearly and eventually goes to zero.

When the input AC power supply 1 is inverted from the polarity shown in FIG. 6, the diode 61 is replaced by the diode 62, the diode 31 is replaced by the diode 32, and the diode 33.
Instead, the diodes 34 operate.

As described above, the operation of the fourth embodiment is based on N =
If it is 1, it is equivalent to the operation of the first embodiment, and if N <1, it is equivalent to the operation of the second embodiment. (Fifth Embodiment) FIG. 7 shows a fifth embodiment.

7 differs from the configuration of FIG. 5 in that the diodes 31 to 34, the first and second choke coils 51 and 52, and the first and second diodes 61 and 62 shows the structure and connection position.

One end of each of the first and second choke coils 51 and 52 is connected to both ends of the AC input power supply 1.
The other ends of the first choke coil 51 are connected to the anode terminals of the first diode 61 and the diode 31, respectively.
The other end of the choke coil 52 has a second diode 62
And the anode terminal of the diode 32 are connected. First
The cathode terminals of the second diodes 61 and 62 are connected to a connection point between the primary winding 81 and the switch element 9. The cathode terminals of the diodes 31 and 32 are connected to a smoothing capacitor 4.
And the primary winding 81. Diode 3
The cathode terminals 3 and 34 are respectively connected to both ends of the AC input power supply 1, and the anode terminal is connected to a connection point between the switch element 9 and the smoothing capacitor 4.

The operation of the thus configured switching power supply will be described. First, when the input AC power supply 1 has the polarity shown in FIG. 7 and the switch element 9 is on, the diodes 61 and 33 conduct, and the input AC power supply 1 → first choke coil 51 → diode 61 → switch element 9 → A current flows through a route from the diode 33 to the input AC power supply 1. The voltage of the input AC power supply 1 is applied to the first choke coil 51, and this current increases linearly with a slope proportional to the voltage of the input AC power supply 1.

When the switch element 9 is turned off, the diode 31 becomes conductive instead of the diode 61, and the input AC power supply 1 → the first choke coil 51 → the diode 31 → the smoothing capacitor 4 → the diode 33 → the input AC power supply 1 Electric current flows. The voltage difference between the input AC power supply 1 and the smoothing capacitor 4 is applied to the first choke coil 51,
This current decreases linearly and eventually goes to zero.

When the polarity of the input AC power supply 1 is reversed from that of FIG. 5, the second choke coil 52 is used instead of the first choke coil 51, the diode 62 is used instead of the diode 61, the diode 32 is used instead of the diode 31, and the diode Instead of 33, diodes 34 operate.

By repeating the above operation, the current flowing through the first and second choke coils 51 and 52 becomes
The sawtooth waveform has a peak value proportional to the voltage of the input AC power supply 1. The input current waveform smoothed by the filter capacitor 2 has a sine wave shape substantially proportional to the input AC voltage.

As described above, in the fifth embodiment, the operation is the same as that of the configuration shown in FIG. 1. By improving the input current waveform, the power factor can be improved and the harmonic current component can be reduced. Since the currents of the first and second choke coils 51 and 52 flow without passing through the transformer 8 as compared with the switching power supply device shown in the above, the conduction loss can be reduced.

The choke coil 5 is a full-wave rectifier circuit 3
The switch element 9 and the control circuit 40 have a stable potential at a high frequency with respect to the input AC power supply because the switch element 9 and the control circuit 40 are on the positive electrode side as compared with the configuration of FIG. The same is true.

(Sixth Embodiment) FIG. 8 shows a sixth embodiment. 8 is different from the configuration of FIG.
Tertiary winding 83 having one end connected to one end of primary winding 81
And the cathode terminals of the first and second diodes 61 and 62 are connected to the other end of the tertiary winding 83.

The voltage of the smoothing capacitor 4 is Ec, the number of turns of the primary winding 81 is N1, and the number of turns of the tertiary winding 83 is N3.
= (N3 / N1) and its operation will be described. First,
When the input AC power supply 1 has the polarity shown in FIG. 8 and the switch element 9 is on, a voltage of N · Ec is generated in the tertiary winding 83. When the voltage Vi of the input AC power supply 1 is (1-N) Ec
If greater, diodes 61 and 33 conduct,
Input AC power supply 1 → first choke coil 51 → diode 61 → tertiary winding 83 → primary winding 81 → switch element 9
A current flows through the route of → diode 33 → input AC power supply 1 and input AC power supply 1 → first choke coil 51 → diode 61 → tertiary winding 83 → smoothing capacitor 4 → diode 33 → input AC power supply 1. Vi- (1-N) Ec is applied to the first choke coil 51, and this current increases linearly with a slope proportional to Vi- (1-N) Ec.

When the switch element 9 is turned off, the diode 31 becomes conductive instead of the diode 61, and the input AC power supply 1 → the first choke coil 51 → the diode 31 → the smoothing capacitor 4 → the diode 33 → the input AC power supply 1 Electric current flows. The first choke coil 51 has Vi
-Ec is applied and this current decreases linearly and eventually goes to zero.

When the polarity of the input AC power supply 1 is reversed from that of FIG. 8, the second choke coil 52 is used instead of the first choke coil 51, the diode 62 is used instead of the diode 61, the diode 32 is used instead of the diode 31, and the diode Instead of 33, diodes 34 operate.

The operation of the sixth embodiment is equivalent to the operation of the third embodiment if N = 1, and equivalent to the operation of the fourth embodiment if N <1. (Seventh Embodiment) FIG. 9 shows a seventh embodiment.

FIG. 9 is different from the configuration of FIG.
These are the structures and connection positions of the first and second choke coils 51 and 52. One ends of the first and second choke coils 51 and 52 are respectively connected to both ends of the AC input power supply 1. A first diode 6 is connected to the other end of the first choke coil 51.
1 is connected to the anode terminal of the diode 31, and the other end of the second choke coil 52 is connected to the anode terminals of the second diode 62 and the diode 32. The cathode terminals of the first and second diodes are connected to a connection point between the primary winding 81 and the switch element 9. Diodes 31 and 3
2 is connected to a connection point between the smoothing capacitor 4 and the primary winding 81.

The operation of the thus configured switching power supply will be described. First, when the input AC power supply 1 has the polarity shown in FIG. 9 and the switch element 9 is on, the diodes 61 and 33 conduct, and the input AC power supply 1 → first choke coil 51 → diode 61 → switch element 9 → A current flows through the route of the diode 33 → the second choke coil 52 → the input AC power supply 1. (1/2) of the voltage of the input AC power supply 1 is applied to each of the first and second choke coils 51 and 52, and this current increases linearly with a slope proportional to the voltage of the input AC power supply 1.

When the switching element 9 is turned off, the diode 31 becomes conductive instead of the diode 61, and the input AC power supply 1 → the first choke coil 51 → the diode 31 → the smoothing capacitor 4 → the diode 33 → the second choke coil 52 → A current flows through the route of the input AC power supply 1. First
(1/2) of the voltage difference between the input AC power supply 1 and the smoothing capacitor 4 is applied to the second choke coils 51 and 52, respectively, and this current decreases linearly and eventually becomes zero.

When the input AC power supply 1 is inverted from the polarity shown in FIG. 9, the diode 61 is replaced by the diode 62, the diode 31 is replaced by the diode 32, and the diode 33.
Instead, the diodes 34 operate.

By repeating this operation, the current flowing through the first and second choke coils 51 and 52 has a sawtooth waveform having a peak value proportional to the voltage of the input AC power supply 1.
The input current waveform smoothed by the filter capacitor 2 has a sine wave shape substantially proportional to the input AC voltage.

As described above, the operation of the seventh embodiment is the same as that of the configuration shown in FIG. 1. By improving the input current waveform, the power factor can be improved and the harmonic current component can be reduced. First and second choke coils 5
Since the currents of 1,52 flow without passing through the transformer 8,
The conduction loss can be reduced.

(Eighth Embodiment) FIG. 10 shows an eighth embodiment. 10 is different from the configuration of FIG. 9 in that a transformer 8 is provided with a tertiary winding 83 having one end connected to one end of a primary winding 81, and the cathode terminals of the first and second diodes 61 and 62 are connected to the tertiary winding. This is a point connected to the other end of the line 83. The voltage of the smoothing capacitor 4 is Ec, and the number of turns of the primary winding 81 is N
1. The number of turns of the tertiary winding 83 is N3, and N = (N3 / N
1).

The operation of the thus configured switching power supply will be described. First, when the input AC power supply 1 has the polarity shown in FIG. 10 and the switch element 9 is on, a voltage of N · Ec is generated in the tertiary winding 83. If the voltage Vi of the input AC power supply 1 is higher than (1-N) Ec, the diodes 61 and 33 conduct, and the input AC power supply 1 → the first choke coil 51 → the diode 61 → the tertiary winding 83 →
Primary winding 81 → switch element 9 → diode 33 → second
Choke coil 52 → input AC power supply 1 and input AC power supply 1 → first choke coil 51 → diode 61
→ Tertiary winding 83 → Smoothing capacitor 4 → Diode 33 →
A current flows through a route from the second choke coil 52 to the input AC power supply 1. First and second choke coils 51 and 52
Respectively, {Vi- (1-N) Ec} / 2 is applied, and this current linearly increases with a slope proportional to Vi- (1-N) Ec.

When the switch element 9 is turned off, the diode 31 becomes conductive instead of the diode 61, and the input AC power supply 1 → the first choke coil 51 → the diode 31 → the smoothing capacitor 4 → the diode 33 → the second choke coil 52 → A current flows through the route of the input AC power supply 1. First
Each of the second choke coils 51 and 52 has (Vi-
Ec) / 2 is applied and this current decreases linearly and eventually goes to zero.

When the polarity of the input AC power supply 1 is reversed from that of FIG. 10, the diode 61 replaces the diode 61, the diode 32 replaces the diode 31, and the diode 3
Each of the diodes 34 operates instead of the three. Thus, the operation of the eighth embodiment is equivalent to the operation of the first embodiment if N = 1, and equivalent to the operation of the second embodiment if N <1.

(Ninth Embodiment) FIG. 11 shows a ninth embodiment. In FIG. 11, the difference from the configuration of FIG.
The second point is that the second diodes 61 and 62 are first and second capacitors 71 and 72, respectively.

The operation of the thus configured switching power supply will be described. First, when the input AC power supply 1 has the polarity shown in FIG. 11 and the switch element 9 is on, when the input AC power supply 1 → capacitor 71 → switch element 9 → choke coil 5 → diode 33 → input AC power supply 1 Flow increases. The charging of the capacitor 71 proceeds,
When the potential of the connection point between the capacitor 71 and the input AC power supply 1 rises and tries to become higher than the potential of the smoothing capacitor 4, the diode 31 conducts, and the input AC power supply 1 → diode 31
→ smoothing capacitor 4 → choke coil 5 → diode 3
3 → Current flows through the route of the input AC power supply 1.

When the switch element 9 is turned off, a current flows through the route of the input AC power supply 1 → the diode 31 → the smoothing capacitor 4 → the choke coil 5 → the diode 33 → the input AC power supply 1, and at the same time, the exciting current of the transformer 8 becomes the primary winding. Wire 81 → capacitor 71 → diode 31 → primary winding 81
, And discharges the electric charge stored in the capacitor 71.

When the input AC power supply 1 is inverted from the polarity shown in FIG. 11, the diode 61 is replaced by the diode 62, the diode 31 is replaced by the diode 32, the diode 3
Each of the diodes 34 operates instead of the three.

FIG. 12 shows the operation waveforms of the respective parts due to the repetition of such an operation. 12A shows an output voltage waveform of the full-wave rectifier circuit 3, FIG. 12B shows a current waveform flowing through the choke coil 5, and FIG. 12C shows an input current waveform. The current flowing through the choke coil 5 is a continuous current that follows the voltage of the input AC power supply 1. The input current waveform is obtained by smoothing the waveform with the filter capacitor 2.

As described above, in the ninth embodiment, it is possible to improve the power factor and reduce the harmonic current component by improving the input current waveform. Furthermore, the current of the choke coil 5 flows without passing through the transformer 8 shown in FIG. 31 and becomes a continuous current having a smaller amplitude as compared with the first to eighth embodiments, so that conduction loss can be reduced.

(Tenth Embodiment) FIG. 13 shows a tenth embodiment. 13, the first and second diodes 61 and 62 differ from the configuration of FIG.
Are the capacitors 71 and 72 of FIG. The number of turns of the primary winding 81 is N1, the number of turns of the tertiary winding 83 is N3,
Let N = (N3 / N1).

As described above, in the tenth embodiment, if N = 1, the operation is equivalent to that of the ninth embodiment, and if N <1, the operation of the second embodiment is different from that of the first embodiment. The same effect can be obtained for the ninth embodiment.

(Eleventh Embodiment) FIG. 14 shows an eleventh embodiment. 14, the first and second diodes 61 and 62 are different from the configuration of FIG.
Are the capacitors 71 and 72 of FIG.

The operation of the thus configured switching power supply will be described. First, when the input AC power supply 1 has the polarity shown in FIG. 14 and the switch element 9 is on, the input AC power supply 1 → the capacitor 71 → the first choke coil 5
1 → switch element 9 → diode 33 → input AC power supply 1
The current flows in the route of and increases. When the charging of the capacitor 71 proceeds, the potential at the connection point between the capacitor 71 and the input AC power supply 1 rises, and when the potential of the connection point becomes higher than the potential of the smoothing capacitor 4, the diode 31 conducts, and the input AC power supply 1 → the diode 31 → the second Current flows through the route of the choke coil 52 → the smoothing capacitor 4 → the diode 33 → the input AC power supply 1.

When the switch element 9 is turned off, a current flows through the route of the input AC power supply 1 → diode 31 → second choke coil 52 → smoothing capacitor 4 → diode 33 → input AC power supply 1, and at the same time, the exciting current of the transformer 8 Flows through the route of primary winding 81 → capacitor 71 → diode 31 → primary winding 81, and discharges the charge stored in capacitor 71.

When the polarity of the input AC power supply 1 is reversed from that in FIG. 14, the diode 62 is used instead of the diode 61, the diode 32 is used instead of the diode 31, and the diode 3 is used.
Each of the diodes 34 operates instead of the three.

As described above, in the eleventh embodiment, the operation equivalent to that of the ninth embodiment is performed, and the effect of the third embodiment with respect to the first embodiment is the same as that of the ninth embodiment. It is in. (Twelfth Embodiment) FIG. 15 shows a twelfth embodiment.

FIG. 15 differs from the configuration of FIG. 6 in that the first and second diodes 61 and 62 are first and second capacitors 71 and 72, respectively. The number of turns of the primary winding 81 is N1, the number of turns of the tertiary winding 83 is N3, and N = (N3 / N1).

As described above, in the twelfth embodiment, if N = 1, the operation is equivalent to that of the ninth embodiment. If N <1, the operation of the twelfth embodiment is different from that of the first embodiment. The same effect can be obtained for the eleventh embodiment.

(Thirteenth Embodiment) FIG. 16 shows a thirteenth embodiment. In FIG. 16, the first and second diodes 61 and 62 are different from the configuration of FIG.
Are the capacitors 71 and 72 of FIG.

The operation of the thus configured switching power supply will be described. First, when the input AC power supply 1 has the polarity shown in FIG. 16 and the switch element 9 is ON, the input AC power supply 1 → the first choke coil 51 → the capacitor 7
1 → switch element 9 → diode 33 → input AC power supply 1
The current flows in the route of and increases. The charging of the capacitor 71 progresses, and the potential at the connection point between the capacitor 71 and the first choke coil 51 rises. When the potential of the connection point becomes equal to or higher than the potential of the smoothing capacitor 4, the diode 31 conducts, and the input AC power supply 1 → first Current flows through the route of the choke coil 51 → the diode 31 → the smoothing capacitor 4 → the diode 33 → the input AC power supply 1.

When the switch element 9 is turned off, a current flows through the route of the input AC power supply 1 → the first choke coil 51 → the diode 31 → the smoothing capacitor 4 → the diode 33 → the input AC power supply 1, and at the same time, the exciting current of the transformer 8 Flows through the route of primary winding 81 → capacitor 71 → diode 31 → primary winding 81, and discharges the charge stored in capacitor 71.

When the input AC power supply 1 is inverted from the polarity shown in FIG. 16, the second choke coil 52 is used instead of the first choke coil 51, the diode 62 is used instead of the diode 61, the diode 32 is used instead of the diode 31, and the diode Instead of 33, diodes 34 operate.

As described above, in the thirteenth embodiment, an operation equivalent to that of the ninth embodiment is performed, and the effect of the fifth embodiment with respect to the first embodiment is also similar to that of the ninth embodiment. is there. (Fourteenth Embodiment) FIG. 17 shows a fourteenth embodiment.

FIG. 17 is different from the configuration of FIG. 8 in that the first and second diodes 61 and 62 are first and second capacitors 71 and 72, respectively. If the number of turns of the primary winding 81 is N1, the number of turns of the tertiary winding 83 is N3, and N = (N3 / N1), if N = 1, the operation is equivalent to that of the ninth embodiment. If <1, the first
The effect of the second embodiment on the thirteenth embodiment is similar to that of the thirteenth embodiment.

FIG. 18 shows a fifteenth embodiment of the present invention.
5 shows an example. 18 differs from the configuration of FIG. 9 in that first and second diodes 61 and 62 are first and second capacitors 71 and 72, respectively.

The operation of the thus configured switching power supply will be described. First, when the input AC power supply 1 has the polarity shown in FIG. 18 and the switch element 9 is on, the input AC power supply 1 → the first choke coil 51 → the capacitor 7
The current flows along the route of 1 → switch element 9 → diode 33 → second choke coil 52 → input AC power supply 1 and increases. When the charging of the capacitor 71 proceeds, the potential at the connection point between the capacitor 71 and the first choke coil 51 rises, and when the potential goes beyond the potential of the smoothing capacitor 4, the diode 31 conducts, and the input AC power supply 1 → the first choke. Current flows through the route of the coil 51 → the diode 31 → the smoothing capacitor 4 → the diode 33 → the second choke coil 52 → the input AC power supply 1.

When the switching element 9 is turned off, when a current flows through the route of the input AC power supply 1 → first choke coil 51 → diode 31 → smoothing capacitor 4 → diode 33 → second choke coil 52 → input AC power supply 1 At the same time, the exciting current of the transformer 8 flows through the route of the primary winding 81 → the capacitor 71 → the diode 31 → the primary winding 81,
The charge stored in the capacitor 71 is discharged.

When the input AC power supply 1 is inverted from the polarity shown in FIG. 18, the diode 62 is used instead of the diode 61, the diode 32 is used instead of the diode 31, and the diode 3 is used.
Each of the diodes 34 operates instead of the three.

As described above, the fifteenth embodiment operates in the same manner as the ninth embodiment. (Sixteenth Embodiment) FIG. 19 shows a sixteenth embodiment.

In FIG. 19, the first and second diodes 61 and 62 are different from the configuration of FIG.
This is the point that the second capacitors 71 and 72 are used. If the number of turns of the primary winding 81 is N1, the number of turns of the tertiary winding 83 is N3, and N = (N3 / N1), if N = 1, the operation is equivalent to that of the ninth embodiment. If <1, the first
The effect of the second embodiment with respect to the fifteenth embodiment is the same as that of the fifteenth embodiment.

FIG. 3 shows the second embodiment, FIG. 6 shows the fourth embodiment, FIG. 8 shows the sixth embodiment, FIG. 10 shows the eighth embodiment, and the tenth embodiment. 13 and 12 showing
15 showing the embodiment of FIG. 15, FIG. 17 showing the fourteenth embodiment,
In FIG. 19 showing the sixteenth embodiment, the configuration of the tertiary winding 83 is as shown in FIG. 20A, but it goes without saying that a configuration as shown in FIG. 20B is also possible.

(Seventeenth Embodiment) FIG. 21 shows a seventeenth embodiment. 21 differs from the configuration of FIG. 1 in that a parallel circuit of a capacitor 73 and a choke coil 53 is connected between the cathode terminals of the first and second diodes 61 and 62, the primary winding 81 and the switch element 9. That is the point.

The switching power supply device thus configured operates almost in the same manner as the ninth embodiment. First, when the input AC power supply 1 has the polarity shown in FIG. 21 and the switch element 9 is ON, the input AC power supply 1 → the diode 61 →
Capacitor 73 → switch element 9 → choke coil 5 →
A current flows through the route from the diode 33 to the input AC power supply 1 and increases. At the same time, the choke coil 53 connected in parallel with the capacitor 73 is excited. When the switch element 9 is turned off, a current flows through the route of the input AC power supply 1 → the diode 31 → the smoothing capacitor 4 → the choke coil 5 → the diode 33 → the input AC power supply 1, and at the same time, the exciting current of the choke coil 53 is stored in the capacitor 73. It flows in a direction to discharge the charged electric charge.

When the polarity of the input AC power supply 1 is reversed from that in FIG. 21, the diode 61 is replaced by the diode 62, the diode 31 is replaced by the diode 32, the diode 3
Each of the diodes 34 operates instead of the three.

That is, the capacitor 73 plays the role of the first and second capacitors 71 and 72 in the ninth embodiment. When the switch element 9 is off, the charge of the first and second capacitors 71 and 72 is transferred. The choke coil 53 plays the role of the primary winding 81 that discharges.

The seventeenth embodiment differs from the first embodiment in that a parallel circuit of a capacitor 73 and a choke coil 53 is connected in series with first and second diodes 61 and 62 as shown in FIG. 1, a parallel circuit of a capacitor 74 and a choke coil 54 is connected to a first diode 61 as shown in FIG.
By providing a parallel circuit of a capacitor 75 and a choke coil 55 in series with the second diode 62 in series, a switching power supply device that operates in the same manner as in the seventeenth embodiment can also be obtained.

Further, these configurations are applied to the above-described second to eighth embodiments, and the same operation can be performed. (Eighteenth Embodiment) FIGS. 23 and 24 show an eighteenth embodiment.

FIG. 23 differs from FIG. 1 in that
The function of the control circuit 40 controls the switching frequency in accordance with the voltage of the smoothing capacitor 4. The point that the on / off ratio of the switch element 9 is controlled so that the output DC voltage is stabilized is the same as in the related art and the above embodiments.

The switching power supply configured as described above operates almost in the same manner as the first embodiment. The input / output voltage ratio of a DC / DC converter represented by the feedforward converter used in the embodiment of the present invention is represented by the on / off ratio of the switch element 9. Therefore, when the switching frequency is fixed, the on-time and off-time of the switching element 9 hardly change depending on the output current.
Even if the output current becomes small, the energy per switching cycle inputted through the choke coil 5 or the first and second choke coils 51 and 52 hardly changes. Therefore, when the output current decreases, the voltage of the smoothing capacitor 4 rises as shown by the characteristic A in FIG. 24 so that the input / output power is balanced, and the switch element 9 and the smoothing capacitor 4 need to have a high withstand voltage. Become.

On the other hand, in the eighteenth embodiment, the control circuit 40 has a function of detecting the voltage of the smoothing capacitor 4 and increasing the switching frequency to increase the switching frequency. When the output current decreases and the voltage of the smoothing capacitor 4 increases, the switching frequency also increases, and the choke coil 5 or the first and second choke coils 51,
The energy per switching cycle input via 52 is reduced. Therefore, it is possible to suppress an increase in the voltage of the smoothing capacitor 4 as shown by the characteristic B in FIG.

FIG. 25 is a circuit diagram showing a specific example of the control circuit 40. The reference numerals of the terminals correspond to those of the control circuit 40 in FIG. A portion surrounded by a broken line in the drawing is a portion having the function described in the present embodiment.

In FIG. 25, reference numeral 400 denotes a control IC, which uses a model number M51977. Reference numerals 401 and 402 denote resistors, and reference numeral 403 denotes a capacitor. 401 and 402 determine the charge / discharge current of the capacitor 403. The charge / discharge time is the maximum on-time and the minimum off-time, and the sum thereof is the switching cycle. 404 and 405 are resistors, 406
Denotes a shunt regulator, and 407 denotes a photocoupler, which detects an output DC voltage and returns it to the control IC 400. The control IC 400 determines the ON time so as to stabilize the output DC voltage, and outputs a drive pulse to the switch element 9.
The time obtained by subtracting the ON time from the switching cycle is the OFF time. 408 and 409 are resistors; 410 is a shunt regulator; 411 and 412 are diodes;
Reference numeral 414 denotes a resistor. The voltage of the smoothing capacitor 4 detected by the resistors 408 and 409 is input to the shunt regulator 410. When the voltage of the smoothing capacitor 4 rises to a predetermined voltage or more, the diode 411 and the resistor 413 and the diode 412 and the resistor 414 Current through the capacitor 4
03 charge / discharge current is increased. That is, the switching frequency increases. Even if the switching frequency changes, the control IC 400 determines the ON time within the changed maximum ON time so as to stabilize the output DC voltage.

As described above, in the eighteenth embodiment, a rise in the voltage of the smoothing capacitor 4 can be suppressed, so that the switch element 9 and the smoothing capacitor 4 having a low breakdown voltage can be used.

In the eighteenth embodiment, the voltage of the smoothing capacitor 4 is detected by resistance division. However, the winding voltage of the transformer 8 generated when the switch element 9 is turned on is detected. It goes without saying that a voltage corresponding to the voltage may be detected.

Although the control circuit 40 shown in this embodiment is applied to the first embodiment, it goes without saying that it can be applied to any of the second to seventeenth embodiments.

(Nineteenth Embodiment) FIGS. 26 and 27 show the first embodiment.
9 shows an embodiment. 26 differs from the configuration of FIG. 11 in that the larger the flowing current, the smaller the inductance value of the choke coil 5 has the performance as shown in FIG. 27.

The switching power supply configured as described above operates almost in the same manner as the ninth embodiment. However, in the ninth embodiment, as the output current decreases, the voltage of the smoothing capacitor 4 increases as described in the eighteenth embodiment. In the case of the ninth embodiment, the current flowing through the choke coil 5 when the switch element 9 is on is equal to the current flowing through the choke coil 5 and the first and second capacitors 71 and 71.
At the resonance current of 72, it does not increase linearly as in the first embodiment. Therefore, when the output current is large, even if the inductance value of the choke coil 5 is small, it does not significantly affect the operation of the switching power supply. on the other hand,
When the output current is small, it is preferable that the inductance value of the choke coil 5 be large in order to suppress a rise in the voltage of the smoothing capacitor 4.

On the other hand, in the nineteenth embodiment, since the choke coil 5 has the performance of decreasing the inductance value as the current increases, the same operation as in the ninth embodiment occurs when the output current is large. When the output current is small, the rise in the voltage of the smoothing capacitor 4 is suppressed more than in the ninth embodiment. The characteristic A in FIG. 28 indicates the voltage increasing characteristic of the smoothing capacitor 4 of the ninth embodiment, and the characteristic B indicates the voltage increasing characteristic of the smoothing capacitor 4 of the nineteenth embodiment.

A choke coil 5 having such performance
Regardless of magnetic saturation, the number of turns of the winding may be reduced and the gap between the magnetic cores may be reduced. That is, the choke coil 5 can be downsized.

When the nineteenth embodiment and the eighteenth embodiment are used in combination, it is needless to say that the width of change of the switching frequency is reduced and the switching frequency is more effective. Further, the choke coil 5 shown in this embodiment is applied to the ninth embodiment, but it goes without saying that it can be applied to any of the tenth to seventeenth embodiments. When the choke coil 5 has the configuration of the first and second choke coils 51 and 52, the first and second choke coils 51 and 5 are used.
In this case, the performance shown in FIG.

In FIG. 31 showing the prior invention example, a series circuit of the diode 10 and the quaternary winding 84 is provided at both ends of the smoothing capacitor 4 so that the magnetic reset of the transformer 4 can be performed efficiently. However, the diode 10 and the quaternary winding 8
The effect of the presence or absence of the series circuit No. 4 on the operation of the present invention was not so great as to the effect of the present invention, and was not indispensable for the description of the present invention.

In each of the embodiments, a circuit configuration based on a feedforward converter has been described. However, similar effects can be obtained also based on other DC / DC converters.

[0115]

According to the structure of the first aspect, the current of the choke coil flows without passing through the transformer, so that the conduction loss can be reduced. Therefore, it is possible to realize an excellent switching power supply device having a high power factor, an input characteristic having a small input current harmonic component, and a high efficiency.

According to the configuration of claim 2, since the current of the choke coil flows without passing through the tertiary winding when the switch element is off, the conduction loss can be reduced. Also, by setting the turns ratio N <1 between the primary winding and the tertiary winding,
The withstand voltage of the diode can be reduced as compared with the first embodiment.

According to the configuration of claim 3, the current of the first and second choke coils flows without passing through the transformer, so that the conduction loss can be reduced. Also, choke coil 5
The switch element and the control circuit have a stable potential at a high frequency with respect to the input AC power supply, so that malfunction is less likely to occur because the switch element and the control circuit are located on the positive electrode side as compared with claim 1 which is disposed on the negative electrode side of the full-wave rectifier circuit.

According to the configuration of claim 4, if N = 1, it is equivalent to claim 1, and if N <1, it is equivalent to the operation of the second embodiment. According to the configuration of claim 5, since the currents of the first and second choke coils flow without passing through the transformer, the conduction loss can be reduced. Also, since the choke coil is disposed on the positive electrode side as compared with the configuration of claim 1 in which the choke coil is disposed on the negative electrode side, the switch element and the control circuit have a stable potential at a high frequency with respect to the input AC power supply, and malfunction. Less likely to wake up.

According to the configuration of claim 6, if N = 1, it is equivalent to claim 3, and if N <1, it is equivalent to claim 4. According to the configuration of claim 7, similar to claim 1,
By improving the input current waveform, it is possible to improve the power factor and reduce the harmonic current components, and the current of the first and second choke coils flows without passing through a transformer, thereby reducing conduction loss. Can be.

According to the configuration of claim 8, if N = 1, it is equivalent to claim 1, and if N <1, it is equivalent to claim 2. According to the configuration of the ninth aspect, it is possible to improve the power factor and reduce the harmonic current component by improving the input current waveform.
Further, since the current of the choke coil flows without passing through the transformer and becomes a continuous current having a smaller amplitude as compared with the above respective claims, conduction loss can be reduced.

According to the tenth aspect, if N = 1, the operation is equivalent to the ninth aspect, and if N <1, the breakdown voltage of the diode can be reduced as compared with the ninth aspect. it can.

According to the eleventh aspect, since the choke coil is on the positive electrode side of the full-wave rectifier circuit, the switch element and the control circuit have a stable potential at a high frequency with respect to the input AC power supply. Malfunction is less likely to occur.

According to the twelfth aspect, if N = 1, the operation is equivalent to that of the ninth aspect, and if N <1, the breakdown voltage of the diode can be reduced as compared with the case of the eleventh aspect. it can.

According to the structure of claim 13, the choke coil is equivalent to that of claim 9 and is located on the positive electrode side as compared with the structure of claim 9 in which the choke coil is arranged on the negative electrode side of the full-wave rectifier circuit. The control circuit has a stable potential at a high frequency with respect to the input AC power supply, and is less likely to malfunction.

According to the structure of claim 14, if N = 1, the operation is equivalent to that of claim 9, and if N <1, the breakdown voltage of the diode can be reduced as compared with the case of claim 13. it can.

According to the configuration of claim 15, the same operation as in claim 9 is performed. According to the configuration of claim 16, claim 9 is
When N <1, the breakdown voltage of the diode can be reduced as compared with the case of claim 15.

According to the seventeenth aspect, in any one of the first to eighth aspects, a parallel circuit of a third choke coil and a capacitor is interposed in series with the first and second diodes. , Can improve the characteristics.

According to the eighteenth aspect, when the output current decreases and the voltage of the smoothing capacitor 4 increases, the control circuit increases the switching frequency, and the control circuit increases the switching frequency via the choke coil or the first and second choke coils. The input energy per switching cycle decreases,
An increase in the voltage of the smoothing capacitor can be suppressed, and a low withstand voltage switch element or smoothing capacitor can be used.

According to the configuration of claim 19, in any one of claims 1 to 18, since the inductance value of the choke coil is reduced as the flowing current increases, the voltage of the smoothing capacitor increases. Is suppressed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment.

FIG. 2 is an input waveform diagram of the embodiment.

FIG. 3 is a configuration diagram of a second embodiment.

FIG. 4 is an input waveform diagram of the embodiment.

FIG. 5 is a configuration diagram of a third embodiment.

FIG. 6 is a configuration diagram of a fourth embodiment.

FIG. 7 is a configuration diagram of a fifth embodiment.

FIG. 8 is a configuration diagram of a sixth embodiment.

FIG. 9 is a configuration diagram of a seventh embodiment.

FIG. 10 is a configuration diagram of an eighth embodiment.

FIG. 11 is a configuration diagram of a ninth embodiment.

FIG. 12 is an input waveform diagram of the embodiment.

FIG. 13 is a configuration diagram of a tenth embodiment.

FIG. 14 is a configuration diagram of an eleventh embodiment.

FIG. 15 is a configuration diagram of a twelfth embodiment.

FIG. 16 is a configuration diagram of a thirteenth embodiment.

FIG. 17 is a configuration diagram of a fourteenth embodiment.

FIG. 18 is a configuration diagram of a fifteenth embodiment.

FIG. 19 is a configuration diagram of a sixteenth embodiment.

FIG. 20 shows the second, fourth, sixth, eighth, tenth, twelfth, fourteenth, and sixteenth.
Configuration Diagram of Main Part in Example

FIG. 21 is a configuration diagram of a seventeenth embodiment.

FIG. 22 is a configuration diagram of a main part of the embodiment.

FIG. 23 is a configuration diagram of an eighteenth embodiment.

FIG. 24 is a characteristic diagram of a main part of the embodiment.

FIG. 25 is a main part circuit diagram of the embodiment.

FIG. 26 is a configuration diagram of a nineteenth embodiment.

FIG. 27 is a characteristic diagram of the choke coil of the embodiment.

FIG. 28 is a characteristic diagram of a main part of the embodiment.

FIG. 29 is a circuit configuration diagram of a conventional switching power supply device.

FIG. 30 is a characteristic diagram of a main part of a conventional example.

FIG. 31 is a circuit configuration diagram of a switching power supply explaining a problem to be solved by the invention.

FIG. 32 is a characteristic diagram of a main part of the conventional example.

[Explanation of symbols]

 Reference Signs List 1 input AC power supply 3 full-wave rectifier circuit 31 third diode 32 fourth diode 33 fifth diode 34 sixth diode 4 smoothing capacitor 5 choke coil 51 first choke coil 52 second choke coil 53 third Choke coil 61 First diode 62 Second diode 71 First capacitor 72 Second capacitor 73 Third capacitor 8 Transformer 81 Primary winding of transformer 82 Secondary winding of transformer 83 Tertiary winding of transformer 9 Switch element 20 Rectifier smoothing circuit 25 Load 40 Control circuit

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yoshinori Kobayashi 10-13 Minamicho, Hanno City, Saitama Prefecture Inside Shindengen Industry Co., Ltd. (72) Inventor Yutaka Sekine 10-13 Minamimachi, Hanno City, Saitama Prefecture Shindengen (56) References JP-A-5-328724 (JP, A) JP-A-7-23563 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02M 7 / 00-7/40 H02M 3/28

Claims (19)

(57) [Claims] 1. A full-wave rectifier circuit for rectifying an input AC power, a transformer having one end of a primary winding connected to a positive output terminal of the full-wave rectifier circuit, and a second end connected to the other end of the primary winding of the transformer. Switch element, a smoothing capacitor connected in parallel to a series circuit of the primary winding of the transformer and the switch element, an anode terminal is connected to each of the input terminals of the full-wave rectifier circuit, and the cathode terminal is A first and a second diode connected to a connection point between the primary winding of the transformer and the switch element, and a connection point between the switch element and the smoothing capacitor and a negative output terminal of the full-wave rectifier circuit; A rectifying and smoothing circuit for rectifying and smoothing the output of the secondary winding of the transformer to supply a DC output voltage to a load; and stabilizing the DC output voltage of the rectifying and smoothing circuit. And a control circuit for controlling the on / off ratio of the switch element as described above. 2. A transformer comprising a tertiary winding having one end connected to one terminal of a primary winding, and a connection point between cathode terminals of first and second diodes being connected to the primary of the transformer.
Instead of connecting to the connection point between the winding and the switch element
The switching power supply according to claim 1 , wherein the switching power supply is connected to the other end of the tertiary winding. 3. A full-wave rectifier circuit for rectifying an input AC power supply, first and second diodes having anode terminals connected to input terminals of the full-wave rectifier circuit and cathode terminals connected to each other, A transformer having a primary winding and a secondary winding; a switch element connected between one end of the primary winding of the transformer and a negative output terminal of the full-wave rectifier circuit; A first choke coil connected to a positive output terminal and the other end connected to the other end of the primary winding of the transformer; one end connected to the cathode terminals of first and second diodes; A second choke coil connected to a connection point between the primary winding of the transformer and the switch element and electromagnetically coupled to the first choke coil, and connected in parallel to a series circuit of the primary winding of the transformer and the switch element Flat A smoothing capacitor, a rectifying and smoothing circuit for rectifying and smoothing the output of the secondary winding of the transformer and supplying a DC output voltage to a load, and turning on and off the switching element so that the DC output voltage of the rectifying and smoothing circuit is stabilized. And a control circuit for controlling the ratio. 4. A transformer is provided with a tertiary winding having one end connected to one terminal of a primary winding, and a connection point at the other end of the second choke coil is connected to the primary winding of the transformer by a switch.
4. The switching power supply device according to claim 3 , wherein the switching power supply device is connected to the other end of the tertiary winding instead of being connected to a connection point with the switch element. 5. A transformer having first and second choke coils, one end of which is connected to both ends of an input AC power supply and electromagnetically coupled to each other, a transformer having a primary winding and a secondary winding, and a primary winding of the transformer. A switching element connected to one end of a wire; a smoothing capacitor connected in parallel to a series circuit of the primary winding of the transformer and the switching element;
First and second diodes having an anode terminal connected to the other end of each of the choke coils and a cathode terminal connected to a connection point between the primary winding of the transformer and the switch element; An anode terminal is connected to the other end of each of the choke coils, and third and fourth diodes whose cathode terminals are connected to a connection point between the primary winding of the transformer and the smoothing capacitor. And a fifth diode, a sixth diode each having an anode terminal connected to a connection point between the switch element and the smoothing capacitor, and rectifying and smoothing the output of the secondary winding of the transformer to obtain a direct current. A rectifying / smoothing circuit that supplies an output voltage to a load, and a control circuit that controls an on / off ratio of the switch element so that a DC output voltage of the rectifying / smoothing circuit is stabilized. For example was the switching power supply device. 6. A transformer is provided with a tertiary winding having one end connected to one terminal of a primary winding, and a connection point between cathode terminals of first and second diodes is connected to the primary of the transformer.
Instead of connecting to the connection point between the winding and the switch element
6. The switching power supply according to claim 5 , wherein the switching power supply is connected to the other end of the tertiary winding. 7. A first and a second choke coil having one end connected to both ends of the input AC power supply and electromagnetically coupled to each other, and a rectifying input AC power supply via the first and the second choke coils. A rectifying circuit, a transformer having a primary winding having one end connected to a positive output terminal of the full-wave rectifier circuit, and the other end of the primary winding of the transformer and a negative output terminal of the full-wave rectifying circuit. A switching element connected to the primary winding of the transformer and a smoothing capacitor connected in parallel to a series circuit of the switching element; an anode terminal connected to each of the input terminals of the full-wave rectifier circuit; Rectifies and smoothes an output of a secondary winding of the transformer and first and second diodes connected to a connection point between the primary winding of the transformer and the switch element, and supplies a DC output voltage to a load. A switching power supply device, comprising: a rectifying / smoothing circuit for controlling the switching element so as to stabilize a DC output voltage of the rectifying / smoothing circuit. 8. A transformer is provided with a tertiary winding having one end connected to one terminal of a primary winding, and a connection point between cathode terminals of the first and second diodes is connected to the primary of the transformer.
Instead of connecting to the connection point between the winding and the switch element
8. The switching power supply according to claim 7 , wherein the switching power supply is connected to the other end of the tertiary winding . 9. A full-wave rectifier circuit for rectifying an input AC power supply, a transformer having a primary winding having one end connected to a positive output terminal of the full-wave rectifier circuit, and a transformer having a primary winding connected to the other end of the primary winding of the transformer. One end is connected to each of the connected switching element, the smoothing capacitor connected in parallel to the series circuit of the primary winding of the transformer and the switching element, and the other end is connected to each of the input terminals of the full-wave rectifier circuit. A first and a second capacitor connected to a connection point between the primary winding of the transformer and the switch element; and a connection between a connection point between the switch element and the smoothing capacitor and a negative output terminal of the full-wave rectifier circuit. A rectifying and smoothing circuit for rectifying and smoothing the output of the secondary winding of the transformer and supplying a DC output voltage to a load; and a DC output voltage of the rectifying and smoothing circuit being stabilized. And a control circuit for controlling an on / off ratio of the switch element. 10. provided tertiary winding having one end to one terminal of the primary winding is connected to the transformer, the first, the connection point of the second capacitor, a primary winding of the transformer switch
10. The switching power supply device according to claim 9 , wherein the switching power supply device is connected to the other end of the tertiary winding instead of being connected to a connection point with the switching device. 11. A full-wave rectifier circuit for rectifying an input AC power supply, first and second capacitors having one end connected to each of input terminals of the full-wave rectifier circuit and the other end connected to each other, A transformer having a winding and a secondary winding, a switch element connected between one end of the primary winding of the transformer and a negative output terminal of the full-wave rectifier circuit, and a positive output of the full-wave rectifier circuit. A first choke coil having one end connected to the terminal and the other end connected to the other end of the primary winding of the transformer, one end connected to a connection point between the first and second capacitors, and the other end connected to the transformer A second choke coil connected to a connection point between the primary winding and the switch element and electromagnetically coupled to the first choke coil, and connected in parallel to a series circuit of the primary winding of the transformer and the switch element And smoothing capacitor A rectifying and smoothing circuit that rectifies and smoothes the output of the secondary winding of the transformer and supplies a DC output voltage to a load; and controls an on / off ratio of the switch element so that the DC output voltage of the rectifying and smoothing circuit is stabilized. A switching power supply device comprising a control circuit. 12. A transformer is provided with a tertiary winding having one end connected to one terminal of a primary winding, and a connection point at the other end of the second choke coil is connected to the primary winding of the transformer by a connection.
The switching power supply device according to claim 11 , wherein the switching power supply device is connected to the other end of the tertiary winding instead of being connected to a connection point with the switch element . 13. A transformer having first and second choke coils, one end of which is connected to both ends of an input AC power supply and electromagnetically coupled to each other, a primary winding and a secondary winding, and a primary winding of the transformer. A switch element connected to one end of the winding, a smoothing capacitor connected in parallel to a series circuit of the primary winding of the transformer and the switch element, and one end connected to the other end of each of the first and second choke coils. Are connected, and the other end is connected to a connection point between the primary winding of the transformer and the switch element. An anode is connected to the other end of each of the first and second choke coils. And a third terminal connected to the connection point between the primary winding of the transformer and the smoothing capacitor, and a cathode terminal connected to both ends of the input AC power supply. And the fifth and sixth diodes having anode terminals connected to the connection points between the switch element and the smoothing capacitor, and rectifying and smoothing the output of the secondary winding of the transformer to apply a DC output voltage to the load. A switching power supply device comprising: a rectifying / smoothing circuit to be supplied; and a control circuit that controls an on / off ratio of the switch element so that a DC output voltage of the rectifying / smoothing circuit is stabilized. 14. A transformer is provided with a tertiary winding having one end connected to one of terminals of a primary winding, and a connection point of the first and second capacitors is connected to the primary winding of the transformer by a switch.
14. The switching power supply according to claim 13 , wherein the switching power supply device is connected to the other end of the tertiary winding instead of being connected to a connection point with the switching element. 15. A first and second choke coil having one end connected to both ends of an input AC power supply and electromagnetically coupled to each other, and a rectifying input AC power supply via the first and second choke coils. Wave rectifier circuit, a transformer having a primary winding having one end connected to a positive output terminal of the full-wave rectifier circuit, and between the other end of the primary winding of the transformer and a negative output terminal of the full-wave rectifier circuit. One end is connected to each of the input terminals of the full-wave rectifier circuit, and the other end is connected to a smoothing capacitor connected in parallel to a series circuit of the primary winding of the transformer and the switch element. Both the first and second capacitors connected to the connection point between the primary winding of the transformer and the switch element and the output of the secondary winding of the transformer are rectified and smoothed to supply a DC output voltage to the load. Rectification flat A switching power supply device comprising: a smoothing circuit; and a control circuit that controls an on / off ratio of the switch element such that a DC output voltage of the rectifying and smoothing circuit is stabilized. 16. trans provided the tertiary winding having one end connected to either terminal of the primary winding, the first, second co
The connection point of the capacitor is connected to the primary winding of the transformer.
The switching power supply device according to claim 15 , wherein the switching power supply device is connected to the other end of the tertiary winding instead of being connected to a connection point with the switching device. 17. The switching power supply according to claim 1, wherein a parallel circuit of a third choke coil and a capacitor is interposed in series with the first and second diodes. 18. A control circuit for detecting a voltage of a smoothing capacitor or a voltage corresponding to a voltage of a smoothing capacitor, and changing a switching frequency of a switch element so as to stabilize the detected voltage. The switching power supply device according to any one of claims 1 to 17. 19. The choke coil or the first and second choke coils have such a characteristic that the inductance value decreases as the flowing current increases.
The switching power supply device according to any one of claims 1 to 18.