JP4407156B2 - Rectifier circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rectifier circuit that rectifies input voltages of, for example, an AC 100V system and an AC 200V system to obtain a DC voltage.
[0002]
[Prior art]
For example, in a power supply circuit that obtains a DC power supply by inputting an AC voltage such as a commercial AC power supply, a rectifier circuit for rectifying and smoothing the AC voltage to obtain a DC voltage (rectified and smoothed voltage) before stabilization is provided. As such a rectifier circuit, a rectifier circuit that is compatible with a so-called wide-range AC 100 V system and AC 200 V system commercial AC power supply is known.
[0003]
In such a rectifier circuit, switching to the voltage doubler rectifier circuit is performed in response to the input of AC 100V commercial AC power, and in response to the input of AC 200V commercial AC power, for example, Switching to the equal voltage rectifier circuit by the bridge rectifier circuit is performed. As a result of switching in this way, a nearly equal level of rectified and smoothed voltage can be obtained between the AC100V system and the AC200V system, which is compatible with a wide range.
[0004]
FIG. 4 is a diagram showing an example of such a rectifier circuit.
In the rectifier circuit shown in FIG. 4, the anode of the rectifier diode D51 and the cathode of the rectifier diode D53 are connected to one AC input terminal t51 to which an AC input voltage ACin from a commercial AC power supply or the like is input. Further, the anode of the rectifier diode D52 and the cathode of the rectifier diode D54 are connected to the other AC input terminal t52 to which the AC input voltage ACin is input.
[0005]
The cathodes of the rectifier diodes D51 and D52 are connected to the positive electrode side of the smoothing capacitor C51. The anodes of the rectifier diodes D53 and D54 are connected to the negative electrode side of the smoothing capacitor C52.
The negative electrode side of the smoothing capacitor C51 is connected to the positive electrode side of the smoothing capacitor C52. The switch element SW51 is connected between the connection point of the smoothing capacitor C51 and the smoothing capacitor C52 and the AC input terminal t52. in this case, Switch element SW51 A relay switch of a relay circuit or a manual switch is used.
[0006]
In such a rectifier circuit, a bridge rectifier circuit is formed by the rectifier diodes D51 to D54 when the switch element SW51 is OFF. When the switch element SW51 is on, a voltage doubler rectifier circuit using the rectifier diode D51 and the rectifier diode D53 is formed. That is, the rectifier circuit shown in FIG. 4 is formed so that the circuit configuration can be switched to the bridge rectifier circuit or the voltage doubler rectifier circuit by turning on / off the switch element SW51.
[0007]
Incidentally, in the rectifier circuit shown in FIG. 4, when the rectification method is automatically switched according to the input voltage level, the switch element SW51 is formed by a relay circuit. It is conceivable to provide a control circuit unit that switches the on / off state of the switch element SW51 formed by the relay switch of the relay circuit in accordance with the input voltage level.
However, when switching the rectification method of the rectifier circuit as described above, a power of about several watts is required due to the relay drive power for driving the relay circuit, the power consumption consumed in the control circuit unit, and the like. Become.
[0008]
As a rectifier circuit that can be switched between a voltage doubler rectifier circuit and a bridge rectifier circuit, a rectifier circuit as shown in FIG. 5 has also been proposed.
In the rectifying circuit shown in FIG. 5, the switch element SW51 is formed by a bidirectional thyristor. In this case, the gate of the bidirectional thyristor serving as the switch element SW51 is connected to the control circuit unit 51 via the resistor R51, and the on / off control of the bidirectional thyristor is performed from the control circuit unit 51.
[0009]
However, when a rectifier circuit is formed using a bidirectional thyristor for the switch element SW51 in this way, the power consumption of the control circuit unit 51 is reduced so that the bidirectional thyristor can be driven stably even at a low voltage. Increase.
Further, the power loss at the resistor R51 inserted between the control circuit unit 51 and the gate of the bidirectional thyristor also increases.
Further, in addition to the voltage drop at the rectifier diodes D51 to D54, a voltage drop of about 0.7 V occurs also in the bidirectional thyristor.
As a result, even when automatic switching between the bridge rectifier circuit and the voltage doubler rectifier circuit is performed by the rectifier circuit as shown in FIG.
[0010]
Therefore, a rectifier circuit as shown in FIG. 6 has been proposed (Patent Document 1).
The rectifier circuit shown in FIG. 6 is configured such that a capacitor C51 is provided between the gate of a bidirectional thyristor that is the switch element SW51 and the control circuit unit 51. That is, in the rectifier circuit shown in FIG. 5, the capacitor C51 is inserted in place of the resistor R51 provided between the gate of the bidirectional thyristor and the control circuit unit 51.
In the rectifier circuit shown in FIG. 6, the bridge rectifier circuit and the voltage doubler rectifier circuit are automatically operated with less power consumption than the rectifier circuit shown in FIG. 5 by turning on and off the gate of the bidirectional thyristor by pulse driving. Switching is performed.
[0011]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-19148
[0012]
[Problems to be solved by the invention]
However, in the rectifier circuit as shown in FIG. 6, a current of several tens of mA is required as a trigger current for driving the bidirectional thyristor that is the switch element SW51.
Considering that the oscillation frequency of the oscillation circuit provided in the control circuit unit 51 is about 100 times the power supply frequency, at least the control circuit unit 51 requires a current of about several mA.
As a result, also in the rectifier circuit shown in FIG. 6, the switching operation between the voltage doubler rectifier circuit and the bridge rectifier circuit is performed. 0.1W ~ 1W Some degree of power was needed.
In such a wide-range rectifier circuit, when switching the rectification method of the rectifier circuit according to the input voltage level, it is desirable that the power consumption consumed for the switching is as small as possible.
[0013]
[Means for Solving the Problems]
In view of the above problems, the present invention includes a rectifier circuit unit formed by bridge-connecting rectifier diodes, and a rectifier circuit unit including two smoothing capacitors connected in series, and rectifying the rectifier circuit unit. A rectified output obtained by rectifying an AC input voltage with a diode is smoothed by a smoothing capacitor, thereby generating a DC voltage as a voltage across two smoothing capacitors connected in series. In the voltage generation circuit, the sources of the two field effect transistors are connected to each other, the drain of one field effect transistor is connected to the connection point of the two smoothing capacitors, and the drain of the other field effect transistor is AC input The two field effect transistors are both off by being connected to the line of one pole of the voltage In the open state, the DC voltage generation circuit is formed as a bridge rectification circuit, and in the short-circuit state where both of the two field effect transistors are turned on, the switching circuit unit switches to form the DC voltage generation circuit as a voltage doubler rectification circuit; The rectifier circuit is configured to include switching means for switching the short circuit state and the open state of the switch circuit unit according to the result of detecting whether the level of the AC input voltage is equal to or higher than a predetermined level.
[0014]
According to the above configuration, switching between on (short circuit) / off (open) is performed, so that the source of the switch circuit that switches between the bridge rectifier circuit and the voltage doubler rectifier circuit is connected to the DC voltage generation circuit. A switch circuit composed of the two field effect transistors thus formed is provided for the DC voltage generation circuit. As a result, the switching of the switching circuit can be controlled by switching the level of the gate voltage with respect to the gate of the field effect transistor.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a rectifier circuit as an embodiment of the present invention will be described.
In FIG. 1, for example, a so-called wide-range rectifier circuit corresponding to an AC input voltage AC100V (AC100V) region such as Japan or the United States and an AC 200V AC (AC220V) region such as Europe. An example will be described.
[0016]
FIG. 1 is a diagram illustrating a configuration of a rectifier circuit according to the present embodiment.
In FIG. 1, an anode of a rectifier diode D6a and a cathode of a rectifier diode D6b of the rectifier circuit unit 2 are connected to a positive AC input terminal t1 to which an AC input voltage from a commercial AC power supply or the like is input. .
Further, the anode of the rectifier diode D6c of the rectifier circuit unit 2 and the cathode of the rectifier diode D6d are connected to the negative-side AC input terminal t2 to which the AC input voltage is input.
[0017]
The cathode of the rectifier diode D6a and the cathode of the diode D6c are connected to the positive side of the smoothing capacitor C5 forming the smoothing circuit unit 8, and the anode of the rectifier diode D6b and the anode of the rectifier diode D6d are connected to the negative side of the smoothing capacitor C6. Has been.
The negative side of the smoothing capacitor C5 is connected to the positive side of the smoothing capacitor C6, and a DC output voltage DCout is obtained as the voltage across the series circuit of the smoothing capacitors C5 to C6.
[0018]
In the rectifier circuit 1 shown in FIG. 1, the switch circuit unit 3 is provided between the connection point of the smoothing capacitors C5 to C6 and the AC input terminal t2.
The switch circuit unit 3 includes two field effect transistors FET1 and FET2 that are resistance elements having no PN junction. In this case, the drain of the field effect transistor FET1 is connected to the AC input terminal t2. The drain of the field effect transistor FET2 is connected to the positive electrode side of the smoothing capacitor C6.
[0019]
The sources of the field effect transistor FET1 and the field effect transistor FET2 are connected to each other. The gates of the field effect transistor FET1 and the field effect transistor FET2 are also connected in common.
In this case, as shown, a parasitic diode Dp1 is formed between the drain and source of the field effect transistor FET1, and a parasitic diode Dp2 is formed between the drain and source of the field effect transistor FET2.
[0020]
When the switch circuit unit 3 is configured by using the two field effect transistors FET1 and FET2, the gate potential of the switch circuit unit 3 is greater than or equal to a predetermined level with respect to the source potential of the field effect transistors FET1 and FET2, for example. The field effect transistors FET1 and FET2 are both turned on. Further, when the gate potentials of the field effect transistors FET1 and FET2 become zero bias, for example, both the field effect transistors FET1 and FET2 are turned off.
In this way, by changing the gate voltage level applied to each gate of the field effect transistor FET1 and the field effect transistor FET2 and turning on / off the field effect transistor FET1 and the field effect transistor FET2 in common, as will be described later. Thus, a switch that can be switched between a short-circuited state (ON) and an open state (OFF) can be formed with respect to the line between the connection point of the smoothing capacitors C5 to C6 and the terminal t2 side of the commercial AC power supply AC.
[0021]
A series circuit composed of a resistor R10 and a diode D7 is connected between the sources of the field effect transistors FET1 and FET2 and the negative side of the smoothing capacitor C6. The capacitor C4 provided between the gate and source of the field effect transistors FET1 and FET2 is used as a capacitor for overvoltage protection.
[0022]
In the rectifier circuit 1 shown in FIG. 1, a DC power supply circuit unit 4, a level detection circuit unit 5, and a latch circuit unit 6 are provided as a control circuit unit 7 (switching means).
The DC power supply circuit unit 4 includes a current limiting resistor R1, capacitors C1 and C2, rectifier diodes D1 and D2, and a Zener diode D5.
One end of the current limiting resistor R1 is connected to the AC input voltage line on the AC input terminal t1 side, and the other end is connected to one end of the capacitor C1.
The other end of the capacitor C1 is connected to the anode of the rectifier diode D2, and the other end of the capacitor C1 is connected to the cathode of the rectifier diode D1.
[0023]
The cathode of the rectifier diode D2 is connected to one end of the smoothing capacitor C2 and the cathode of the Zener diode D5, and the anode of the rectifier diode D1 is connected to the other end of the smoothing capacitor C2 and the anode of the Zener diode D5.
The cathode of the rectifier diode D2 is connected to the gates of the field effect transistors FET1 and FET2 constituting the switch circuit unit 3 via the resistors R5 and R9.
[0024]
The level detection circuit unit 5 includes a resistor R2, a resistor R3, a resistor R4, a rectifier diode D3, a Zener diode D4, and a PNP transistor Q1.
The emitter of the transistor Q1 is connected to an AC input voltage line on the AC input terminal t1 side, and its base is connected to the AC input voltage line of the AC input terminal t1 via a resistor R4. Also that collector Is connected to one end of a resistor R6 of the latch circuit section 6.
[0025]
The base of the transistor Q1 is connected to the cathode of the Zener diode D4. The anode of the Zener diode D4 is connected to the anode of the rectifier diode D3, and the cathode is connected to the connection point of the resistors R2 and R3 connected between the AC input terminals t1 and t2.
[0026]
The latch circuit section 6 includes resistors R6, R7, R8, a capacitor C3, a PNP transistor Q2, and an NPN transistor Q3.
The emitter of the transistor Q2 is connected to a connection line of resistor R5 to resistor R9, which is an output voltage line of the DC power supply circuit unit 4.
[0027]
The connection point between the resistor R5 and the resistor R9 is connected to the base of the transistor Q2 and the transistor Q3 via the resistor R8. collector It is connected to the.
The emitter of the transistor Q2 is connected to the connection point of the resistors R5 and R9, and the collector of the transistor Q2 is connected to the base of the transistor Q3.
The base of the transistor Q3 is connected to the collector of the transistor Q1 of the level detection circuit unit 5 via the resistor R6, and a resistor R7 and a capacitor C3 are connected between the base and emitter of the transistor Q3.
[0028]
The operation of the rectifier circuit 1 configured as described above is as follows.
First, as a rectifying operation, when the switch circuit unit 3 is off (open) and the input voltage at the AC input terminal t1 is a positive level, the path is rectifier diode D6a → smoothing capacitor C5 → smoothing capacitor C6 → rectifier diode D6d. Current flows. When the input voltage at the AC input terminal t2 is a positive level, a current flows through the path of the rectifier diode D6c → smoothing capacitor C5 → smoothing capacitor C6 → rectifier diode D6b. As a result, the smoothing capacitors C5 and C6 are charged.
That is, when the switch circuit unit 3 is off, the rectifier circuit unit 2 and Smoothing circuit 8 The circuit part (DC voltage generation circuit) consisting of the above operates as a bridge rectifier circuit, and a DC output voltage DCout corresponding to the same level of the AC input voltage level is obtained from both ends of the smoothing capacitors C5 and C6 connected in series. Will be.
[0029]
On the other hand, when the switch circuit unit 3 is on (short-circuited) and the input voltage at the AC input terminal t1 is at a positive level, the rectifier diode D6a → smoothing capacitor C5 → field effect transistor FET2 (drain-source) → field effect. Transistor FET1 (Source-drain) → Current flows through the path of the AC input terminal t2, and the smoothing capacitor C5 is charged.
Similarly, when the switch circuit unit 3 is on and the input voltage of the AC input terminal t2 is at a positive level, the field effect transistor FET1 (drain-source) → the field effect transistor FET2 (Source-drain) → Smoothing capacitor C6 → Rectifier diode D6b → Current flows through the AC input terminal t1, and the smoothing capacitor C6 is charged.
That is, when the switch circuit unit 3 is on, the rectifier circuit unit 2 operates as a voltage doubler rectifier circuit, and the DC output voltage DCout corresponding to the voltage doubler level of the AC input voltage is generated from both ends of the smoothing capacitors C5 and C6. Will be obtained.
[0030]
Further, as can be seen from the path of the rectified current when the switch circuit unit 3 is on (short-circuited), the rectified current is expressed as the AC input voltage (AC in) is inverted in polarity. Flows through the source-drain and parasitic diode of both FETs in parallel It is like that. In other words, in the present embodiment, as the switch circuit unit 3, the sources of two field effect transistors each having a parasitic diode are connected to each other, so that the rectified current that is inverted according to both positive and negative polarities ( This constitutes a so-called AC switch in which an alternating current) flows.
[0031]
The operation of the DC power supply circuit unit 4 is as follows. When the input voltage at the AC input terminal t1 is a positive level, the current limiting resistor R1, the capacitor C1, the rectifier diode D2, the smoothing capacitor C2, the parasitic diode Dp1, and the AC input terminal t2. A current flows through the path and the smoothing capacitor C2 is charged.
[0032]
When the input voltage at the AC input terminal t2 is positive and the switch circuit unit 3 is off, the rectifier diode D6c → smoothing capacitor C5 → smoothing capacitor C6 → resistor R10−diode D7 → rectifier diode D1 → capacitor C1 → current. A current flows through the path of the limiting resistor R1 → the AC input terminal t1, and the capacitor C1 is discharged.
Similarly, when the input voltage of the AC input terminal t2 is positive and the switch circuit unit 3 is ON, the AC input terminal t2, the field effect transistor FET1, the rectifier diode D1, the capacitor C1, the current limiting resistor R1, and the AC input terminal. A current flows through the path t1, and the capacitor C1 is discharged.
By such an operation of the DC power supply circuit unit 4, a DC power supply voltage for driving the field effect transistor of the switch circuit unit 3 is obtained as the voltage across the smoothing capacitor C2. The DC power supply voltage is stabilized by a Zener diode D5 connected in parallel with the smoothing capacitor C2.
[0033]
Here, in the rectifier circuit 1, the capacitor C 1 is provided in the DC power supply circuit section 4, and the AC current is limited using the reactance of the capacitor C 1, thereby increasing the reactive current flowing in the DC power supply circuit section 4 and consuming it. The power is reduced.
When the capacitor C1 is provided in this way, the power consumption can be reduced to 1/10 or less of that when the current is limited only by the current limiting resistor R1.
[0034]
Further, the current limiting resistor R1 in this case limits such a current because a large current flows into the DC power supply circuit unit 4 only with the capacitor C1 when spiked noise is superimposed on the AC voltage input line. It is provided for this purpose.
[0035]
Further, the operation of the level detection circuit unit 5 is that the potential difference between the base voltage applied to the base of the transistor Q1 via the resistor R4 and the voltage at the connection point between the resistors R2 and R3 is the breakdown of the Zener diode D4. When the voltage becomes higher than the voltage, the base current flows through the transistor Q1, and the transistor Q1 is turned on.
Here, the resistance values of the resistors R2 and R3 are set so that the transistor Q1 is turned on and current is supplied to the latch circuit section 6 via the resistor R6 when the AC input voltage level is 200V AC. Yes.
[0036]
In the latch circuit section 6, when the current is supplied from the level detection circuit section 5, that is, when the AC input voltage is an AC 200V system, the transistors Q2 and Q3 are turned on. Accordingly, at this time, the DC current supplied from the DC power supply circuit section 4 through the resistor R5 flows through the path from the transistor Q2 to the transistor Q3.
That is, when the AC input voltage is AC200V, the DC voltage level of the DC power supply circuit unit 4 is not applied as the gate voltage to the gates of the field effect transistors FET1 and FET2 of the switch circuit unit 3, and the switch circuit unit. 3 is turned off, and the rectifier circuit unit 2 operates as a bridge rectifier circuit.
[0037]
On the other hand, when no current is supplied to the latch circuit unit 6 from the level detection circuit unit 5, that is, when the AC input voltage is 100V AC, the transistors Q2 and Q3 are turned off. Accordingly, at this time, the DC voltage of the DC power supply circuit unit 4 is applied to the gates of the field effect transistors FET1 and FET2 of the switch circuit unit 3. As a result, the switch circuit unit 3 is turned on, and the rectifier circuit unit 2 operates as a voltage doubler rectifier circuit.
[0038]
Note that once the transistors Q2 and Q3 provided in the latch circuit section 6 are turned on, the DC power supply circuit section 4 supplies a current of a predetermined holding current or higher even if the current supply from the transistor Q1 is lost. The on state is maintained by continuing to be performed. That is, the operation is maintained.
In the configuration of the level detection circuit 5, detection is performed during a half-wave period in one cycle of the AC input voltage, so that the current supply from the transistor Q1 is only a half-wave period in one cycle of the AC input voltage, and the other. During the half-wave period, no current is supplied from the transistor Q1. However, since the latch circuit 6 is provided, the latch circuit 6 maintains the previous operation state even in a half-wave period in which the current supply from the transistor Q1 is stopped, and the switch circuit 3 is also in the off state. Maintained.
In addition, since the latch circuit 6 is provided, for example, even when the voltage level of the AC input voltage of AC200V system fluctuates and the detection operation of the level detection circuit unit 5 becomes unstable, the rectifier circuit unit 2 can It operates as a rectifier circuit. This prevents the rectifier circuit unit 2 from being erroneously switched to the AC 100 V system voltage doubler rectifier circuit when the AC input voltage is AC 200 V.
[0039]
As described above, in the rectifier circuit 1 shown in FIG. 1, the switch circuit unit 3 is configured by using the field effect transistors FET1 and FET2 which are resistance elements having no PN junction. When the switch circuit unit 3 is formed in this way, the conduction state between the switch circuit units 3 is turned on (short circuit) only by changing the gate voltage applied to the gates of the two field effect transistors FET1 and FET2. Alternatively, the rectifier circuit portion 2 can be switched to a bridge rectifier circuit or a voltage doubler rectifier circuit.
[0040]
Further, in the rectifier circuit 1 configured as described above, when the switch circuit unit 3 is turned on / off, the gates of the field effect transistors FET1 and FET2 hardly flow except for a leakage current. Almost no power loss.
[0041]
Furthermore, if an appropriate element is used for the field effect transistor element used in the switch circuit unit 3, the voltage drop in the switch circuit unit 3 is smaller than when a bidirectional thyristor is used as the switch element as in the prior art. There is an advantage that you can.
[0042]
Furthermore, since the drive current for turning on / off the field effect transistors FET1, FET2 of the switch circuit unit 3 is actually very small, the DC power supply circuit unit 4, the level detection circuit unit 5, the latch circuit unit The resistance of the control circuit section 7 composed of 6 can be increased.
As a result, since the current flowing through the control circuit unit 7 can be reduced, the power consumption in the control circuit unit 7 can also be reduced.
[0043]
According to the experiment, it is confirmed that the power consumption of the rectifier circuit 1 shown in FIG. 1 is 1.25 mW when the AC input voltage is AC100V (AC100V) and 5.59 mW when the AC200V (AC220V). It was done.
That is, it has been confirmed that the rectifier circuit unit 2 is switched with very little power consumption as compared with the power consumption (0.1 W to 1 W) when the switch circuit is configured by a bidirectional thyristor as in the prior art.
[0044]
Even in the field effect transistor FET, when high-speed switching is performed, it is necessary to quickly charge and discharge the charge of the gate capacitance, and thus a large capacity is required as the gate drive capacity. However, in the case of the rectifier circuit 1, the switching operation of the switch circuit unit 3 is a usage mode in which the field effect transistors FET1 and FET2 are fixed to either on or off according to the commercial AC voltage in the region of use. Since no switching speed is required, a large gate drive capability is not required, and only a small amount of drive power is required.
[0045]
FIG. 2 is a diagram illustrating a configuration of a rectifier circuit according to the second embodiment.
Note that the same circuit parts as those in FIG. In FIG. 2 as well, a wide range rectifier circuit of AC100V to AC200V will be described as an example.
[0046]
The rectifier circuit section 2 shown in FIG. 2 is different from the rectifier circuit 1 shown in FIG. 1 in the circuit configuration of the level detection circuit.
That is, in the rectifier circuit unit 2 shown in FIG. 2, the level detection circuit unit 12 is constituted by capacitors C11, C12, C13, rectifier diodes D11, D12, and a Zener diode D13, and the current limiting resistor R1 of the DC power supply circuit unit 4 A series circuit of capacitors C11 and C12 is connected to a connection point with the capacitor C1.
In this case, the cathode of the rectifier diode D11 and the anode of the rectifier diode D12 are connected to the connection point between the capacitors C11 and C12.
Further, one end of the smoothing capacitor C13 and the cathode of the Zener diode D13 are connected to the cathode of the rectifier diode D12.
The anode of the rectifier diode D11, the other end of the smoothing capacitor C13, and the other end of the capacitor C12 are connected in common.
[0047]
Further, in the rectifier circuit 11 shown in FIG. 2, the diode D7 and the resistor R10 provided in the rectifier circuit 1 shown in FIG. 1 are deleted, and the AC input terminal t2 and the field effect of the switch circuit unit 3 are used instead. A capacitor C7 is provided between the sources of the transistors FET1 and FET2.
[0048]
In the rectifier circuit 11 shown in FIG. 2, a control circuit unit 13 (switching means) is formed by the DC power supply circuit unit 4, the level detection circuit unit 12, and the latch circuit unit 6.
[0049]
First, as the operation of the DC power supply circuit section 4 of the rectifier circuit 11 shown in FIG. 2, when the input voltage of the AC input terminal t1 is a positive level, the current limiting resistor R1 → capacitor C1 → rectifier diode as in FIG. A current flows through a path of D2 → smoothing capacitor C2 → parasitic diode Dp1 → AC input terminal t2, and the smoothing capacitor C2 is charged.
When the input voltage at the AC input terminal t2 is positive, a current flows through the path of the capacitor C7 → rectifier diode D1 → capacitor C1 → current limiting resistor R1 → AC input terminal t1, and the capacitor C1 is discharged. .
In this case as well, a DC power supply for driving the switch circuit unit 3 is obtained as the voltage across the smoothing capacitor C2.
[0050]
In the level detection circuit unit 12 of the rectifier circuit 11 shown in FIG. 2, the input voltage is divided by the capacitors C11 and C12 to detect the input voltage level. That is, the input voltage divided by the reactance elements C11 and C12 is rectified by the rectifier diodes D11 and D12, and the transistors Q2 and Q3 are turned on when the rectified voltage is equal to or higher than the breakdown voltage of the Zener diode D13. Yes.
[0051]
Therefore, for example, when the input voltage level is AC200V, the transistors Q2 and Q3 of the latch circuit unit 6 are turned on. Conversely, when the input voltage level is AC100V, the transistors Q2 and Q3 of the latch circuit 6 are turned off.
That is, as in FIG. 1 described above, when the AC input voltage is an AC 200 V system, the switch circuit unit 3 is turned off, and the rectifier circuit unit 2 operates as a bridge circuit. On the other hand, when the AC input voltage is an AC 100V system, the switch circuit unit 3 is turned on, and the rectifier circuit unit 2 operates as a voltage doubler rectifier circuit.
[0052]
When the rectifier circuit 11 is configured as shown in FIG. 2, as shown in FIG. 1, the voltage dividing voltage is applied between the positive electrode side and the negative electrode side of the AC input voltage line that is set to a high voltage. Since it is not necessary to provide the resistors R2 and R3, the power consumption can be reduced by the amount of no power loss in the resistors R2 and R3.
[0053]
When the AC input voltage is divided by reactance elements (capacitors C11 and C12) as in the rectifier circuit 11 shown in FIG. 2, the current flowing through the capacitors C11 and C12 is a reactive current, and the generated power is also invalid. Since it becomes power and does not become effective power, it is assumed that there is no increase in power consumption by the capacitors C11 and C12. Thereby, there exists an advantage that power consumption can be reduced further than the rectifier circuit 1 shown in the said FIG.
[0054]
According to the experiment, it was confirmed that the rectifier circuit 11 shown in FIG. 2 can reduce the AC input voltage to 0.07 mW when the AC input voltage is 100 V AC and 0.12 mW when the AC input voltage is 220 V AC.
[0055]
In the level detection circuit unit 12 of the rectifier circuit 11 shown in FIG. 2, the voltage dividing circuit is formed by the capacitors C11 and C12. However, the voltage dividing circuit can also be configured using resistors. Further, for example, either one of the capacitors C11 and C12 of the voltage dividing circuit can be constituted by a resistor.
[0056]
However, when the voltage dividing circuit is composed only of the capacitors C11 and C12, it can be made independent of the frequency of the AC input voltage. However, when either one of the capacitors C11 and C12 is composed of a resistor, the level A level difference in which the output voltage of the detection circuit unit 12 depends on the frequency of the AC input voltage is generated.
Incidentally, since the current limiting resistor R1 provided in the rectifier circuit 11 is extremely small compared to the impedances of the capacitors C11 and C12, the frequency dependence due to the current limiting resistor R1 can be almost ignored.
[0057]
FIG. 3 is a diagram illustrating a configuration of a rectifier circuit according to the third embodiment.
In addition, the same code | symbol is attached | subjected to the same site | part as FIG. 1, and description is abbreviate | omitted.
In FIG. 3, for example, a rectifier circuit used in a standby power circuit (standby power supply circuit) provided in an electronic device or the like will be described as an example.
[0058]
The rectifier circuit 21 shown in FIG. 3 is provided on the secondary side of the power transformer T1 in which a commercial AC voltage or the like is input to the primary side winding as the AC input voltage Vin.
In this case, the anode of the rectifier diode D6a forming the rectifier circuit section 2 and the cathode of the rectifier diode D6b are connected to one terminal t21 of the secondary winding of the power transformer T1. Further, the anode of the rectifier diode D6c and the cathode of the rectifier diode D6d forming the rectifier circuit section 2 are connected to the other terminal t22 of the secondary winding of the power transformer T1.
[0059]
The cathodes of the rectifier diode D6a and the diode D6c forming the rectifier circuit unit 2 are connected to the positive side of the smoothing capacitor C5 forming the smoothing circuit unit 8, and the anodes of the rectifier diodes D6b and D6d are the smoothing capacitor C6. Connected to the negative electrode side.
[0060]
Also in this case, the negative side of the smoothing capacitor C5 is connected to the positive side of the smoothing capacitor C6, and a series circuit is formed by these smoothing capacitors C5 and C6.
The DC voltage DCpre of the smoothing circuit 8 formed by the series circuit of the smoothing capacitors C5 and C6 is made constant by a three-terminal series regulator IC (hereinafter simply referred to as “regulator IC”) and the smoothing capacitor C22. Thus, the output is made as the DC output voltage DCout. A noise removing capacitor C21 is provided between the input terminal and the GND terminal of the regulator IC.
In this case, the switch circuit unit 3 using the field effect transistors FET1 and FET2 is provided between the connection point of the smoothing capacitors C5 and C6 and the secondary winding terminal t22 of the power transformer T1.
[0061]
In this case, a resistor R22 is provided between the gate and source of the field effect transistors FET1 and FET2 together with a capacitor C4 for overvoltage protection. The sources of the field effect transistors FET1 and FET2 are connected to the negative electrode side via a resistor R23.
[0062]
Further, such a rectifier circuit 21 is provided with a control circuit unit 24 (switching means) including a drive circuit unit 22 and a level detection circuit unit 23.
The drive circuit unit 22 includes transistors Q21, Q22, and Q24 and resistors R24, R25, R26, R27, R30, R31, and R32.
In this case, the emitter of the transistor Q21 is connected to the input line of the regulator IC, and its collector is connected to the gates of the field effect transistors FET1 and FET2 forming the switch circuit section 3 via the resistor R21.
The base of the transistor Q21 is connected to the input line via the resistor R24 and is connected to the collector of the transistor Q22 via the resistor R25.
The base of the transistor Q22 is connected to the collector of the transistor Q23 of the level detection circuit section 23 through a resistor R26, and is connected to the negative electrode line through a resistor R27. The emitter of the transistor Q22 is connected to the negative electrode line.
[0063]
The base of the transistor Q24 is connected to the collector of the transistor Q23 of the level detection circuit section 23 through the resistor R31 and is connected to the negative electrode line through the resistor R32.
The collector of the transistor Q24 is connected to the base of the transistor Q23 via the resistor R29 of the level detection circuit unit 23, and is connected to the negative electrode line via the resistor R30. Note that the emitter of the transistor Q24 is connected to the negative electrode line.
[0064]
On the other hand, the level detection circuit unit 23 of the control circuit unit 24 includes a transistor Q23 and resistors R28 and R29.
In this case, the emitter of the transistor Q23 is connected to the output line of the regulator IC, and its collector is connected to the base of the transistor Q22 via the resistor R26 and the base of the transistor Q24 via the resistor R31 as described above. ing. The base of the transistor Q23 is connected to the input line via the resistor R28, and is connected to the collector of the transistor Q24 via the resistor R29.
[0065]
In the level detection circuit unit 23 configured as described above, an output voltage output from the regulator IC is used as a reference voltage. For this reason, the output terminal of the regulator IC is connected to the emitter of the transistor Q23, and the input voltage level of the regulator IC (DC voltage DCpre of the smoothing circuit unit 8) becomes higher than the output voltage (reference voltage) of the regulator IC by a predetermined level or more. At this time, the resistance values of the resistors R28, R29, and R30 are set so that the transistor Q23 is turned off.
[0066]
When the level detection circuit unit 23 is configured in this way, when the input level of the regulator IC is higher than the reference voltage and the transistor Q23 is off, the transistors Q22 and Q24 of the drive circuit unit 22 are off and the transistor Q22 is off. In this case, the transistor Q21 is also turned off. As a result, the switch circuit unit 3 is turned off without being applied as a gate voltage to the gates of the field effect transistors FET1 and FET2 of the switch circuit unit 3. That is, when the input voltage level of the regulator IC is equal to or higher than the output voltage (reference voltage) of the regulator IC, the rectifier circuit unit 2 is operated as a bridge rectifier circuit.
[0067]
On the other hand, when the input voltage level of the regulator IC is lower than its output voltage (reference voltage), the transistor Q23 is turned on, and accordingly, the transistors Q22 and Q24 are turned on. When transistor Q22 is turned on, transistor Q21 is turned on. As a result, the gate voltage is applied to the gates of the field effect transistors FET1 and FET2 of the switch circuit unit 3 via the transistor Q21, and the switch circuit unit 3 is turned on.
[0068]
As a result, the rectifier circuit unit 2 operates as a voltage doubler rectifier circuit. When the input voltage level of the regulator IC is equal to or lower than the output voltage (reference voltage) of the regulator IC, the input voltage level of the regulator IC is substantially reduced. It can be as high as twice the voltage level.
[0069]
Note that the rectifier circuit 21 shown in FIG. 3 has a low input voltage level input from the power transformer T1, so that no reactance element is provided for the purpose of reducing the power consumption by limiting the alternating current. Is.
[0070]
As described above, in the rectifier circuit 21 shown in FIG. 3, if the output voltage DCout that has been made constant by the regulator IC is a reference voltage and the input voltage of the regulator IC is equal to or lower than the reference voltage, the rectifier circuit unit 2 and the rectifier circuit unit 8 The voltage doubler rectifier circuit is used as a part, and when the input voltage of the regulator IC is equal to or higher than the reference voltage, the bridge rectifier circuit is replaced.
[0071]
With this configuration, even when the input voltage of the regulator IC changes due to not only the input AC input voltage but also the change in the load current flowing from the output side of the regulator IC to the load (not shown), for example, the voltage change And the rectification method of the rectifier circuit unit 2 can be switched.
[0072]
In the rectifier circuit 21 of the present embodiment, as the field effect transistor used in the switch circuit unit 3, an element having a low voltage and a low voltage drop, for example, an element having a voltage drop of about 0.1 V can be used. Therefore, for example, the power loss can be reduced as compared with the case where the switch circuit unit 3 is configured using a bidirectional thyristor that generates a voltage drop of about 0.7V.
[0073]
Further, when the rectifier circuit 21 is configured in this way, the power consumption in the rectifier circuit can be extremely reduced. Therefore, for example, a low power operation such as a standby power circuit of an electronic device and a reduction in power consumption are required. The present invention is very suitable when applied to a standby power circuit.
For example, if an appropriate element is selected as the field effect transistor FET of the switch circuit unit 3 to reduce the drive current, the current of the entire control circuit unit 24 can be reduced accordingly. For example, when the power consumption of the entire control circuit unit 24 is no load, when the AC input voltage is AC100V system, 0.1 mW or less (AC100V), and when the AC input voltage is AC200V system, up to about 0.2 mW (AC220V) Can be reduced.
[0074]
Note that the configuration of the rectifier circuit described in this embodiment is merely an example, and the rectifier circuit of the present invention has a switch circuit unit that switches the circuit configuration of the rectifier circuit unit 2 to a voltage doubler rectifier circuit or a bridge rectifier circuit. Any rectifier circuit can be used as long as it is composed of effect transistors.
[0075]
【The invention's effect】
As described above, as the rectifier circuit of the present invention, the DC voltage generation circuit including the rectifier circuit unit and the smoothing circuit unit for obtaining the rectified and smoothed voltage by inputting the AC input voltage is the switch circuit ON (short circuit). ) / Off (open), switching is performed between the voltage doubler rectifier circuit and the bridge rectifier circuit. The switch circuit has a configuration as an AC switch using two field effect transistors.
Thereby, the rectifier circuit can be switched by changing the gate voltage to be applied to the gate of the field effect transistor. That is, switching of the rectifier circuit is performed by voltage control. In addition, since the field effect transistor can be regarded as a resistance element, by selecting a transistor suitable for the current used, the voltage drop can be reduced as compared with, for example, a bidirectional thyristor. Therefore, according to the present invention, the rectifier circuit can be switched with very little power consumption.
In addition, since the drive current for turning on / off the field effect transistor forming the switch circuit portion is very small, the resistance of the circuit portion as the switching means is increased, and the amount of current to be flowed is reduced, Furthermore, there is an advantage that power consumption can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a rectifier circuit according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of a rectifier circuit according to a second embodiment.
FIG. 3 is a diagram illustrating a configuration of a rectifier circuit according to a third embodiment.
FIG. 4 is a diagram showing an example of a conventional rectifier circuit.
FIG. 5 is a diagram showing an example of a conventional rectifier circuit.
FIG. 6 is a diagram showing an example of a conventional rectifier circuit.
[Explanation of symbols]
1 11 21 Rectifier circuit, 2 Rectifier circuit section, 3 Switch circuit section, 4 DC power supply circuit section, 5 12 Level detection circuit section, 6 Latch circuit section, 7 13 24 Control circuit section, 22 Drive circuit section, 23 Level detection circuit Part, C capacitor, D diode, FET field effect transistor, IC regulator, Q transistor, R resistor, T1 power transformer

Claims (1)

A rectifier circuit portion which is formed a rectifying diode bridge-connected, and a smoothing circuit consisting of two smoothing capacitors connected in series, obtained by rectifying an AC input voltage by the rectifying diode of the rectifier circuit portion A DC voltage generation circuit that generates a DC voltage as a voltage across the two smoothing capacitors connected in series by smoothing the rectified output by the smoothing capacitor;
The sources of the two field effect transistors are connected to each other, the drain of one field effect transistor is connected to the connection point of the two smoothing capacitors, and the drain of the other field effect transistor is connected to one of the AC input voltages. An open state in which the two field effect transistors are both turned off by connecting to the pole line, connecting both gates of the two field effect transistors to each other and controlling the voltage of both gates Then, the DC voltage generating circuit is formed as a bridge rectifier circuit, and in a short-circuit state where both of the two field effect transistors are turned on, a switch circuit that switches to form the DC voltage generating circuit as a voltage doubler rectifier circuit;
Switching means for switching the switch circuit to either the short circuit state or the open state according to a result of detecting whether the level of the AC input voltage is a predetermined value or more,
The switching means is
A level detection circuit unit that detects that the level of the AC input voltage is equal to or higher than a predetermined value based on a voltage division level obtained by dividing the AC input voltage by a voltage dividing circuit;
A PNP-type transistor and an NPN-type transistor, wherein the base of the PNP-type transistor and the collector of the NPN-type transistor are connected to each other, and the collector of the PNP-type transistor and the base of the NPN-type transistor And a latch circuit portion formed by being connected to each other;
A DC power supply circuit unit for generating a voltage to be supplied to both gates of the two field effect transistors,
The DC power supply circuit unit is
A series circuit of a current limiting capacitor for limiting an alternating current to which the alternating current input voltage is applied and a current limiting resistor for limiting a current caused by spike noise, a rectifier diode connected to the series circuit, and the rectifier diode And a smoothing capacitor that charges the current flowing through, charging and discharging the current limiting capacitor according to a change in polarity of the AC input voltage, generating a DC voltage in the smoothing capacitor,
The level detection circuit unit includes:
When detecting that the level of the AC input voltage is equal to or higher than a predetermined value, a current is passed through the bases of the two transistors of the latch circuit unit to maintain the conduction state of the latch circuit unit,
The latch circuit is
The voltage that is connected to both gates of the two field effect transistors and is supplied from the smoothing capacitor of the DC power supply circuit section to both gates is lowered in the conductive state of the latch circuit, and the 2 A rectifier circuit in which the two field effect transistors are both open .

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