JP5300337B2 - Power supply device and lighting fixture - Google Patents

Description

  The present invention relates to a power supply device using a transformer and a switching element.

In a capacitor input type circuit, it is known that an inrush current suppression circuit is provided in series with a capacitor in an input stage in order to suppress an inrush current at power-on.
In addition, in a circuit using a transformer and a switching element, a transformer configuration that reduces noise generated by the influence of parasitic capacitance in the transformer is known.
Japanese Patent Publication No.63-206160 Japanese Utility Model Publication 2-53232

The inrush current suppression circuit needs to operate correctly based on the voltage charged in the capacitor of the input stage. For this reason, it becomes a subject from where in the circuit the trigger for operating an inrush current control circuit correctly is acquired.
In addition, it is necessary to suppress the generation of noise in order to prevent the noise generated from the circuit from adversely affecting other devices. In particular, a switching power supply inevitably has a problem of suppressing noise radiated to the outside, and it is desired to effectively reduce noise by a method that is as inexpensive as possible.
The present invention has been made, for example, in order to solve the above-described problems. An object of the present invention is to suppress noise generation and to correctly operate an inrush current suppression circuit with a simple circuit configuration.

  A power supply device according to the present invention includes an input smoothing capacitor, an inrush current suppressing circuit that suppresses an inrush current flowing through the input smoothing capacitor, and a transformer that applies an input smoothing voltage charged in the input smoothing capacitor to a primary winding. And an output smoothing capacitor charged by a secondary voltage generated in the secondary winding of the transformer, wherein the transformer has a shield having one end electrically connected to one end of the primary winding. The inrush current suppression circuit has a winding, and controls the suppression of the inrush current based on the shield winding voltage generated at both ends of the shield winding.

  According to the power supply device of this embodiment, noise generated from the transformer can be suppressed due to the effect of the shield winding, and the inrush current suppression circuit can be operated using the shield winding voltage. The circuit configuration of the apparatus can be simplified.

Embodiment 1 FIG.
The first embodiment will be described with reference to FIGS.

FIG. 1 is a block configuration diagram showing a functional block configuration of a lighting fixture 800 according to this embodiment.
The lighting fixture 800 is supplied with power from an AC power source AC such as a commercial power source, and turns on the light source. The lighting fixture 800 includes a power supply device 100 and an LED circuit 810.

  The LED circuit 810 includes one or more LEDs as a light source, and lights the LEDs with a direct current generated by the power supply device 100. When the LED circuit 810 includes a plurality of LEDs, the plurality of LEDs may be electrically connected in series with each other, may be electrically connected in parallel, or may be electrically connected in series and parallel. . Further, when a plurality of LEDs are electrically connected in parallel or in series-parallel, the LED circuit 810 may have a current mirror circuit or the like in order to equalize the currents flowing through the plurality of LEDs.

  The power supply apparatus 100 is a direct current source. The power supply apparatus 100 receives power from the AC power supply AC and generates a DC current that flows through the LED circuit 810. The power supply apparatus 100 includes a noise filter circuit 110, a rectifier circuit 120, an inrush current suppression circuit 130, an input smoothing capacitor C41, a switching circuit 150, a transformer 160, a rectifier element D81, an output smoothing capacitor C82, and an output detection circuit 190.

  The noise filter circuit 110 prevents noise generated outside the lighting fixture 800 from entering the power supply apparatus 100 and prevents noise generated inside the power supply apparatus 100 from leaking outside. The noise filter circuit 110 includes, for example, an across the line capacitor, a common mode choke, a normal mode choke, and the like.

  The rectifier circuit 120 receives a low-frequency AC voltage (for example, 100 V (effective value) 50 Hz or 60 Hz) from the AC power supply AC via the noise filter circuit 110, rectifies the input low-frequency AC voltage, and generates a pulsating voltage. Generate. The rectifier circuit 120 is configured by, for example, a diode bridge. The rectifier circuit 120 has two terminals (hereinafter referred to as “rectification reference terminal” and “rectification output terminal”, respectively) in order to output the generated pulsating voltage. The rectifier circuit 120 outputs the generated pulsating voltage as a potential difference between the rectification output terminal and the rectification reference terminal. The potential of the rectification output terminal is equal to or higher than the potential of the rectification reference terminal. The rectification reference terminal is electrically connected to the primary side ground wiring of the power supply device 100.

  The input smoothing capacitor C41 is a capacitive element. The input smoothing capacitor C41 is charged by the pulsating voltage generated by the rectifier circuit 120, and smoothes the pulsating voltage to generate a DC voltage. The input smoothing capacitor C41 is, for example, an electrolytic capacitor. The input smoothing capacitor C41 has two terminals (hereinafter referred to as “input smoothing anode terminal” and “input smoothing cathode terminal”, respectively). The two terminals are distinguished from each other in consideration of the case where the input smoothing capacitor C41 is a capacitor having polarity, such as an electrolytic capacitor. When the input smoothing capacitor C41 is a capacitor having no polarity, The terminal may be an input smooth anode terminal, and any terminal may be an input smooth cathode terminal. The input smooth cathode terminal is electrically connected to the primary side ground wiring of the power supply device 100.

The inrush current suppression circuit 130 is a circuit for suppressing an inrush current that flows when the input smoothing capacitor C41 is not sufficiently charged when power is supplied to the lighting fixture 800 from the AC power supply AC. The inrush current suppression circuit 130 has three terminals (hereinafter referred to as “suppression reference terminal”, “suppression control terminal”, and “suppression output terminal”, respectively). The suppression reference terminal is electrically connected to the input smoothing anode terminal of the input smoothing capacitor C41. The suppression output terminal is electrically connected to the rectification output terminal of the rectifier circuit 120.
The inrush current suppression circuit 130 changes the electrical resistance value between the suppression output terminal and the suppression reference terminal based on the potential of the suppression control terminal with respect to the suppression reference terminal. Immediately after the power is turned on, the inrush current suppression circuit 130 suppresses the inrush current by increasing the electric resistance value between the suppression output terminal and the suppression reference terminal. After that, after the input smoothing capacitor C41 is sufficiently charged, the inrush current suppression circuit 130 reduces the electric resistance value between the suppression output terminal and the suppression reference terminal, and thereby wasteful power in the inrush current suppression circuit 130 is obtained. Reduce consumption. The details of the inrush current suppression circuit 130 will be described later.

  The transformer 160 has three windings (hereinafter referred to as “primary winding 161”, “secondary winding 162”, and “shield winding 163”, respectively). One end of the primary winding 161 and one end of the shield winding 163 are electrically connected to each other and electrically connected to the input smoothing anode terminal of the input smoothing capacitor C41. One end of the secondary winding 162 is electrically connected to the secondary ground wiring of the power supply device 100. Details of the transformer 160 will be described later.

The switching circuit 150 (power switching circuit) includes a switch (for example, a power FET) that connects between the other end of the primary winding 161 of the transformer 160 and the primary side ground wiring of the power supply device 100. The switching circuit 150 transmits the energy stored in the input smoothing capacitor C41 to the secondary side of the transformer 160 by repeatedly turning on and off the switch at a high frequency (for example, 140 kHz). That is, while the switch is on, the voltage charged in the input smoothing capacitor C41 is applied to the primary winding 161 of the transformer 160, and the energy stored as the electric charge in the input smoothing capacitor C41 is converted into magnetic energy. Store in the transformer 160. When the switch is turned off, the magnetic energy stored in the transformer 160 is transmitted to the secondary side and charges the output smoothing capacitor C82.
Further, the switching circuit 150 changes the frequency and duty ratio for turning on and off the switch based on the load current flowing through the LED circuit 810 detected by the output detection circuit 190, thereby transferring the energy transmitted to the secondary side of the transformer 160. To control the load current to be constant.
In this example, since the load is the LED circuit 810, the load current is controlled. However, the switching circuit 150 may be configured to control the load voltage to be constant.

  Note that a snubber circuit may be provided in parallel with the primary winding 161 in order to reduce noise accompanying switching of the switching circuit 150.

  The rectifying element D81 has two terminals (hereinafter referred to as “rectifying anode terminal” and “rectifying cathode terminal”, respectively). When the potential of the rectifying anode terminal is higher than the potential of the rectifying cathode terminal, the rectifying element D81 has a small electrical resistance value between the rectifying anode terminal and the rectifying cathode terminal, and current flows from the rectifying anode terminal to the rectifying cathode terminal. Flowing. Conversely, when the potential of the rectifying anode terminal is lower than the potential of the current cathode terminal, the rectifying element D81 has an electric resistance value between the rectifying anode terminal and the rectifying cathode terminal that blocks the current. The rectifying element D81 is, for example, a semiconductor diode. As a result, the rectifying element D81 extracts a current for charging the output smoothing capacitor C82 from the secondary winding 162 of the transformer 160. The rectification anode terminal is electrically connected to one end of the secondary winding 162 of the transformer 160.

  The output smoothing capacitor C82 is a capacitance element having two terminals (hereinafter referred to as “output smoothing anode terminal” and “input smoothing cathode terminal”, respectively). The output smoothing capacitor C82 is charged by the current extracted by the rectifying element D81 from the secondary winding 162 of the transformer 160. The voltage charged in the output smoothing capacitor C82 becomes the output of the power supply device 100 and is applied to the LED circuit 810. The The output smooth anode terminal is electrically connected to the rectifier cathode terminal of the rectifier element D81. The output smooth cathode terminal is electrically connected to the secondary ground wiring of the power supply device 100.

  The output detection circuit 190 (detection circuit) detects a load current flowing in the LED circuit 810 that is a load of the power supply apparatus 100. The output detection circuit 190 outputs a signal indicating the detected load current (for example, a signal indicating the current value of the load current itself, or a signal indicating whether the current value of the load current is larger or smaller than a predetermined current value). To do. The signal output from the output detection circuit 190 is input to the switching circuit 150 and controlled so that the load current is constant. When the switching circuit 150 controls not the load current but the load voltage to be constant, the output detection circuit 190 detects the load voltage, not the load current, and outputs a signal representing the detected load voltage.

  Note that the primary side and the secondary side of the power supply apparatus 100 are electrically separated with the transformer 160 interposed therebetween. The switching circuit 150 and the output detection circuit 190 are connected via a separation circuit (feedback circuit) such as a photocoupler. The separation circuit may be in the output detection circuit 190, may be in the switching circuit 150, or may exist separately from the switching circuit 150 and the output detection circuit 190.

  Further, in order to suppress generation of noise due to potential floating, the primary side circuit and the secondary side circuit may be connected via a capacitor or the like. In that case, select a location where the potential is relatively stable on both the primary and secondary sides and use it as the connection point. For example, the primary side uses the primary side ground wiring or the input smoothing anode terminal of the input smoothing capacitor C41 as a connection point, and the secondary side uses the secondary side ground wiring or the output smoothing anode terminal of the output smoothing capacitor C82 as a connection point. .

FIG. 2 is a plan view and a cross-sectional view taken along line AA showing the structure of the transformer 160 in this embodiment.
In addition to the primary winding 161, the secondary winding 162, and the shield winding 163, the transformer 160 includes an iron core 170, a transformer first terminal 171, a transformer second terminal 172, a transformer third terminal 173, and a transformer fourth terminal 174. And a transformer fifth terminal 175.

The primary winding 161 (primary winding) is a conducting wire having one end electrically connected to the transformer third terminal 173 and the other end electrically connected to the transformer second terminal 172. The primary winding 161 is wound around the iron core 170 starting from the side connected to the transformer third terminal 173. The number of turns of the primary winding 161 is, for example, about 100 turns.
The secondary winding 162 (secondary winding) is a conducting wire having one end electrically connected to the transformer fourth terminal 174 and the other end electrically connected to the transformer fifth terminal 175. The secondary winding 162 is wound around the iron core 170 starting from the side connected to the transformer fourth terminal 174.
The shield winding 163 is a conducting wire having one end electrically connected to the transformer second terminal 172 and the other end electrically connected to the transformer first terminal 171. The shield winding 163 is wound around the iron core 170 starting from the side connected to the transformer second terminal 172. The number of turns of the shield winding 163 is, for example, about 40 turns.

  In relation to FIG. 1, the suppression control terminal of the inrush current suppression circuit 130 is electrically connected to the transformer first terminal 171. The transformer second terminal 172 is electrically connected to the suppression reference terminal of the inrush current suppression circuit 130 and the input smoothing anode terminal of the input smoothing capacitor C41. One end of a switch of the switching circuit 150 is electrically connected to the transformer third terminal 173. The transformer fourth terminal 174 is electrically connected to the rectifying anode terminal of the rectifying element D81. An output smoothing cathode terminal of the output smoothing capacitor C82 is electrically connected to the transformer fifth terminal 175.

The primary winding 161, the secondary winding 162, and the shield winding 163 are wound around the same position of the iron core 170 (core) in order to increase the degree of coupling.
The shield winding 163 is wound on the innermost side among the three windings. The shield winding 163 is wound so as to form a single layer over the entire winding position of the iron core 170 (from the end of the bobbin to the end). For example, when the iron core 170 is EE19 and the shield winding 163 is a urethane wire (UEW wire) of φ0.2 mm, it can be wound to the full winding position in about 40 turns. If you want more turns, you can use thinner lines. Conversely, a thicker line may be used to reduce the number of turns.
The primary winding 161 is wound on the iron core 170 on which the shield winding 163 is wound. The secondary winding 162 is wound on the iron core 170 on which the primary winding 161 is further wound.

FIG. 3 is an electric circuit diagram showing a circuit configuration of the inrush current suppression circuit 130 in this embodiment.
The inrush current suppression circuit 130 includes a current limiting element R31, a switching element T32, a rectifying element D33, and a voltage dividing circuit 135.

The current limiting element R31 has two terminals. The current limiting element R31 has a property that the voltage between both terminals increases as the flowing current increases. The current limiting element R31 is, for example, a resistor. In the current limiting element R31, one terminal is electrically connected to the suppression output terminal, and the other terminal is electrically connected to the suppression reference terminal. Thereby, current limiting element R31 suppresses the inrush current immediately after power-on.
The switching element T32 has three terminals (hereinafter referred to as “switch anode terminal”, “switch cathode terminal”, and “switch control terminal”, respectively). When the potential of the switch cathode terminal with respect to the switch control terminal (hereinafter referred to as “switch control voltage”) becomes equal to or higher than a predetermined threshold voltage (for example, 0.6 V), the switching element T32 is connected between the switch anode terminal and the switch cathode terminal. Is conducted, and a current (hereinafter referred to as “switch current”) flows from the switch anode terminal to the switch cathode terminal. The switching element T32 has a holding action, and after that, even if the switch control voltage becomes lower than a predetermined threshold potential, the switching element T32 maintains the conduction state until some trigger is generated. The switching element T32 insulates between the switch anode terminal and the switch cathode terminal, for example, triggered by the switch current falling below a predetermined holding current. The switching element T32 is, for example, a thyristor. The switching element T32 has a switch anode terminal electrically connected to the suppression output terminal and a switch cathode terminal electrically connected to the suppression reference terminal. That is, by turning on the switching element T32, the current limiting element R31 can be short-circuited, and the pulsating voltage generated by the rectifier circuit 120 can be directly applied to the input smoothing capacitor C41. Immediately after the power is turned on, the switching element T32 is turned off to suppress the inrush current due to the effect of the current limiting element R31, and then the switching element T32 is turned on to short-circuit the current limiting element R31 and useless power. Reduce consumption.
The rectifying element D33 (backflow prevention diode) has a rectifying anode terminal and a rectifying cathode terminal, and has a rectifying action. The rectifying element D33 is, for example, a semiconductor diode. The rectification anode terminal is electrically connected to the suppression control terminal. The rectifying element D33 prevents a reverse voltage from being applied to the switching element T32 when the potential of the suppression control terminal becomes lower than the potential of the suppression reference terminal.
The voltage dividing circuit 135 has three terminals (hereinafter referred to as “divided voltage reference terminal”, “divided voltage input terminal”, and “divided voltage output terminal”, respectively). The voltage dividing circuit 135 inputs the potential of the voltage dividing input terminal with respect to the voltage dividing reference terminal, divides the input voltage by resistance, generates a voltage proportional to the input voltage, and generates the generated voltage with respect to the voltage dividing reference terminal. Output as the potential of the voltage division output terminal. The voltage dividing circuit 135 is, for example, a resistor R36 and a resistor R37 connected in series. In the voltage dividing circuit 135, the voltage dividing reference terminal is electrically connected to the suppression reference terminal, the voltage dividing input terminal is electrically connected to the rectifying cathode terminal of the rectifying element D33, and the voltage dividing output terminal is electrically connected to the switch control terminal of the switching element T32. Connected. The voltage dividing circuit 135 divides the voltage (for example, 50 V) input to the suppression control terminal to lower the voltage level, and prevents an overvoltage from being applied to the suppression control terminal of the switching element T32.

  FIG. 4 is a waveform diagram showing the voltage and current of each part of the power supply device 100 according to this embodiment.

At time _{t 1,} the switching circuit 150 turns on the switch. As a result, the primary voltage of the transformer 160 (refers to the voltage across the primary winding 161. The sign of the primary voltage is positive when the potential of the transformer second terminal 172 is higher than the potential of the transformer third terminal 173). The voltage v _C41 charged in the input smoothing capacitor C41 is substantially equal. If the coupling of the primary winding 161, the secondary winding 162, and the shield winding 163 is dense, the secondary voltage of the transformer 160 (the voltage across the secondary winding 162 is indicated. The sign of the secondary voltage is the transformer voltage). The case where the potential of the fourth terminal 174 is higher than the potential of the transformer fifth terminal 175 is assumed to be positive) and the shield winding voltage (the voltage across the shield winding 163. The sign of the shield winding voltage is the primary winding. When the potential of 161 is higher than the potential of the secondary winding 162, the voltage is proportional to the primary voltage according to the turn ratio. Since the secondary voltage has a reverse polarity, it is a negative voltage.
Since the secondary voltage is negative, the rectifying action of the rectifying element D81 causes the secondary current of the transformer 160 (refers to the current flowing in the secondary winding 162. The secondary current sign is the secondary current from the transformer fifth terminal 175. The case of entering the secondary winding 162 and coming out of the transformer fourth terminal 174 is positive). Also, the primary current of the transformer 160 (refers to the current flowing through the primary winding 161. The sign of the primary current indicates that the primary current enters the primary winding 161 from the transformer second terminal 172 and exits from the transformer third terminal 173. Is positively increased with a substantially constant slope due to the current limiting action due to the reactance of the transformer 160.
Since the shield winding voltage is positive, the rectifier element D33 of the inrush current suppression circuit 130 is turned on, and the switch control voltage of the inrush current suppression circuit 130 is a voltage proportional to the shield winding voltage. That is, the switch control voltage is proportional to the voltage v _C41 charged in the input smoothing capacitor C41. If the switch control voltage is equal to or higher than a predetermined threshold voltage, the switching element T32 is turned on. Therefore, immediately after the power is turned on, when the input smoothing capacitor C41 is not yet fully charged, the switching element T32 is turned off, and when the input smoothing capacitor C41 is fully charged, the switching element T32 is turned on.

In time _{t 2, the} switching circuit 150 turns off the switch. For example, the switching circuit 150 turns off the switch when it is determined that the primary current has reached a predetermined value. As a result, the transformer third terminal 173 of the transformer 160 is opened, so that the primary current should theoretically be zero, but it is not completely zero due to the influence of parasitic capacitance. The transformer 160 tries to maintain the current by the current limiting action due to the reactance of the transformer 160. Therefore, the secondary current flows instead of the primary current suddenly decreasing. Since the rectifying element D81 is forcibly turned on halfway, the secondary voltage becomes substantially equal to the voltage v _C82 charged in the output smoothing capacitor C82. Note that transient switching noise occurs due to the effect of the primary current not being completely zero. The primary voltage and the shield voltage are voltages proportional to the secondary voltage (however, the signs are reversed).
Since the shield winding voltage is negative, the rectifier element D33 of the inrush current suppression circuit 130 is turned off, and the switch control voltage of the inrush current suppression circuit 130 becomes substantially 0, which is lower than a predetermined threshold voltage. However, the switching element T32 maintains the ON state due to the holding action of the switching element T32.
Due to the current limiting action due to the reactance of the transformer 160, the secondary current gradually decreases with a substantially constant slope.

At time _{t 3,} the secondary current becomes zero, the rectifying element D81 is turned off. As a result, the transformer fourth terminal 174 of the transformer 160 is opened. Since both the primary winding 161 and the secondary winding 162 of the transformer 160 are in an open state, both the primary current and the secondary current should theoretically become zero, but they are not completely zero due to the influence of the parasitic capacitance, and are transient. Switching noise occurs. The switching noise generated at this time is not attenuated and continues for a long time because both the primary winding 161 and the secondary winding 162 are open and there is no escape of resonance energy between the reactance of the transformer 160 and the parasitic capacitance.

At time _{t 4,} when the switching circuit 150 turns on the switch, in the same state as the time _{t 1.} The power supply apparatus 100 repeats the same operation with this as one cycle.

When the voltage of the AC power supply AC is 100 V (effective value), the voltage v _C41 charged in the input smoothing capacitor C41 is about 130 V due to the influence of a voltage drop in the rectifier circuit 120 and the like.
Assuming that the threshold voltage at which the switching element T32 is turned on is about 0.6V and the voltage dividing ratio of the voltage dividing circuit 135 is 20: 1, for example, when the input smoothing capacitor C41 is sufficiently charged, the shield winding voltage is It needs to be 30V or more. For example, if the turns ratio of the primary winding 161 and the shield winding 163 is 5: 2, when the primary voltage is 130V, the shield winding voltage is 130 × 2/5 = 52V, and the inrush current suppression circuit 130 Works.

In this example, since the power supply apparatus 100 operates as a current source that makes the load current constant, the load voltage changes depending on the electrical characteristics of the LEDs included in the LED circuit 810. For this reason, the voltage v _C82 charged in the output smoothing capacitor C82 is not constant. The flyback voltage v _FB (referred to as the primary voltage between times t _{2 and} t ₃ ) is the number of turns of the primary winding 161 and the secondary winding 162 to the voltage v _C82 charged in the output smoothing capacitor C82. For example, if the turns ratio of the primary winding 161 and the secondary winding 162 is 2: 1, v _FB = v _C82 × 2. Since the voltage v _C82 charged in the output smoothing capacitor C82 is not constant, the flyback voltage v _FB is also not constant.
When the shield winding voltage is negative, the rectifier element D33 is cut, and the inrush current suppression circuit 130 operates regardless of the flyback voltage _vFB . Therefore, it is not necessary to consider the flyback voltage v _FB at the design stage, and the inrush current suppression circuit 130 can be realized with a simple configuration.

As described above, the switching noise is generated at time t ₂ and time t _3, the switches or rectifying element D81 of the switching circuit 150 is turned off, the transformer tertiary terminal 173 and transformers fourth terminal 174 enters an open state caused by. Among them, the noise generated at time t ₂ has a large peak but is attenuated immediately, so the influence on the outside is small. On the other hand, the noise generated at time t ₃ lasts for a long time, so the influence on the outside becomes large. there is a possibility.
In the power supply device 100 in this embodiment, the current that cancels the current flowing from the primary winding 161 or the secondary winding 162 to the iron core 170 via the parasitic capacitance is changed from the shield winding 163 via the parasitic capacitance. Since no noise is accumulated in the iron core 170, noise leaking to the outside can be suppressed.

The power consumed to turn on the switching element T32 is proportional to the voltage input to the suppression control terminal. Since the shield winding voltage decreases as the number of turns of the shield winding 163 decreases, the power consumption in the inrush current suppression circuit 130 can be suppressed.
Since the shield winding 163 in this embodiment is wound on the innermost side, it is closer to the iron core 170 than the primary winding 161 and the secondary winding 162, and the shield winding 163 and the iron The parasitic capacitance between the core 170 is large. For this reason, the number of turns of the shield winding 163 required for generating a current that cancels the current flowing from the primary winding 161 and the secondary winding 162 through the parasitic capacitance may be reduced. Therefore, power consumption in the inrush current suppression circuit 130 can be suppressed.
Further, since the shield winding 163 is wound so as to form one layer, the distance between the primary winding 161 and the iron core 170 can be secured, and the parasitic capacitance between the primary winding 161 and the iron core 170 can be secured. Can be reduced. For this reason, the number of turns of the shield winding 163 may be further reduced.

FIG. 5 is a frequency characteristic diagram showing an experimental result of noise leaking to the AC power supply AC side in the power supply device 100 according to this embodiment.
FIG. 6 is a frequency characteristic diagram showing an experimental result of noise leaking to the AC power supply AC side when the shield winding 163 is wound only to half as a reference example.
5 and 6, the horizontal axis indicates the noise frequency (Hz), and the vertical axis indicates the noise level (dB).
According to this graph, the noise level in the frequency band “a” is reduced when the shield winding 163 is wound in one layer as compared with the case where the shield winding 163 is wound only up to half. I understand that.

The power supply apparatus 100 in this embodiment includes an input smoothing capacitor C41, an inrush current suppressing circuit 130 for suppressing an inrush current flowing through the input smoothing capacitor C41, and an input smoothing voltage v _C41 charged in the input smoothing capacitor C41. A transformer 160 applied to the primary winding 161 and an output smoothing capacitor v _C82 charged by a secondary voltage generated in the secondary winding 162 of the transformer 160. The transformer 160 has one end at one end. The primary winding 161 has a shield winding 163 electrically connected to one end of the primary winding 161, and the inrush current suppression circuit 130 is based on the shield winding voltage generated at both ends of the shield winding 163. Since the suppression of the noise is controlled, the noise generated from the transformer 160 can be suppressed by the effect of the shield winding 163. With wear, by using the shield winding voltage can be operated inrush current suppression circuit 130, it is possible to simplify the circuit configuration of the power supply apparatus 100.

  In the power supply device 100 according to this embodiment, the shield winding 163 of the transformer 160 is wound on the innermost side among the shield winding 163, the primary winding 161, and the secondary winding 162. The number of turns of the shield winding 163 necessary for suppressing noise generated from the transformer 160 is small, the shield winding voltage can be reduced, and the power consumption in the inrush current suppression circuit 130 can be suppressed.

  In the power supply apparatus 100 according to this embodiment, the transformer 160 has an iron core 170, and the shield winding 163 of the transformer 160 is wound around the iron core 170 in one layer, and thus is generated from the transformer 160. The number of turns of the shield winding 163 necessary for suppressing noise is further reduced, the shield winding voltage can be further reduced, and the power consumption in the inrush current suppression circuit 130 can be further suppressed.

  In the power supply device 100 in this embodiment, the inrush current suppression circuit 130 is electrically connected in parallel with the current limiting element R31 connected in series with the input smoothing capacitor C41, and in parallel with the current limiting element R31, and the shield Switching element T32 that conducts when the winding voltage becomes higher than a predetermined voltage. Therefore, when the input smoothing capacitor C41 is not sufficiently charged, the switching element T32 is turned off to suppress the inrush current, When the input smoothing capacitor C41 is sufficiently charged, the switching element T32 is turned on, and the power consumption in the inrush current suppression circuit 130 can be suppressed.

  In the power supply apparatus 100 according to this embodiment, the inrush current suppression circuit 130 includes a rectifier element D33 that rectifies the shield winding voltage by half-wave, and a voltage divider circuit 135 that resistively divides the voltage rectified by the rectifier element D33. And the switching element T32 is turned on when the voltage divided by the voltage dividing circuit 135 is higher than a predetermined voltage. Therefore, if the shield winding voltage is low, the voltage dividing ratio of the voltage dividing circuit 135 is The power consumption for turning on the switching element T32 can be suppressed.

  The lighting fixture 800 in this embodiment has the power supply device 100, and the light source (LED of the LED circuit 810) is turned on by the voltage charged in the output smoothing capacitor C82. Small and wasteful power consumption can be suppressed.

The voltage signal extracted from the shield winding 163 provided to reduce noise is used not only as an inrush current suppression circuit 130 but also as a trigger signal for operating a switching element such as a thyristor constituting another circuit. May be.
As described above, the shield winding 163 (shared winding) has two functions of a function of reducing noise and a function of extracting a trigger signal, so that a countermeasure circuit is individually provided, The circuit configuration of the power supply apparatus 100 can be simplified, the number of parts of the power supply apparatus 100 can be reduced, and the manufacturing cost of the power supply apparatus 100 can be suppressed.
Thereby, the low-cost and highly reliable lighting fixture 800 can be manufactured.

The shield winding 163 is wound in a single layer, and the number of turns is preferably 40 turns or less, and more preferably 10 turns or more and 40 turns or less. Further, it is desirable that the number of turns of the primary winding 161 is 0.45 times or less. The smaller the number of turns of the shield winding 163, the lower the voltage applied to the inrush current suppression circuit 130. Therefore, less power is consumed to turn on the switching element T32 in the inrush current suppression circuit 130. Further, since the reverse voltage applied to the rectifying element D33 due to the flyback voltage v _FB and switching noise (noise due to leakage inductance) is reduced, a diode having a low withstand voltage can be used as the rectifying element D33, and the power supply device 100 manufacturing costs can be reduced.

The polarity of the trigger voltage input by the inrush current suppression circuit 130 is the same as the primary voltage of the transformer 160. Therefore, the maximum value of the trigger voltage is substantially equal to the voltage v _C41 charged in the input smoothing capacitor C41. Therefore, a circuit configuration for controlling the operation of the inrush current suppression circuit 130 based on the voltage v _C41 charged in the input smoothing capacitor C41 can be realized relatively easily. On the other hand, if the polarity of the trigger voltage is the same as the secondary voltage of the transformer 160 (the polarity opposite to the primary voltage), the maximum value of the instantaneous peak of the trigger voltage changes due to the parasitic capacitance of the transformer 160, The relationship with the charging voltage vC41 of the input smoothing capacitor C41 is not necessarily clear. By providing a capacitor in parallel with the resistor R37 in the voltage dividing circuit 135, it is possible to remove an instantaneous peak due to switching noise. In this case, the maximum value is the voltage charged in the output smoothing capacitor C82. v _Determined by _C82 . When the power supply device 100 is configured to operate as a current source, since the load voltage is not constant, the circuit configuration for controlling the operation of the inrush current suppression circuit 130 based on the trigger voltage determined by the voltage v _C82 is described in this embodiment. It must be more complicated than the configuration of the inrush current suppression circuit 130 described.

  Since the level of noise generated inside the power supply apparatus 100 is reduced, the noise removal capability of the noise filter circuit 110 may be low. That is, parts such as the across-the-line capacitor and the common mode choke constituting the noise filter circuit 110 can be reduced. Further, when the capacity of the power supply apparatus 100 is 10 W or less, noise generated inside the power supply apparatus 100 is very low, and thus the noise filter circuit 110 may not be provided. Thereby, the manufacturing cost of the power supply device 100 can be suppressed.

Embodiment 2. FIG.
The second embodiment will be described with reference to FIGS.
Since the configuration of the lighting fixture 800 in this embodiment is the same as that described in Embodiment 1, the description thereof is omitted.

FIG. 7 is a cross-sectional view showing the structure of the transformer 160 in this embodiment.
In this example, a primary winding 161, a secondary winding 162, and a shield winding 163 are wound around the iron core 170 of the transformer 160 in order from the inside.
As described above, the shield winding 163 is wound on the outermost side among the three windings (the primary winding 161, the secondary winding 162, and the shield winding 163), thereby radiating noise radiated from the iron core 170. Can be reduced.

  In the power supply apparatus 100 according to this embodiment, the shield winding 163 of the transformer 160 is wound on the outermost side among the shield winding 163, the primary winding 161, and the secondary winding 162. Radiation noise radiated from the transformer 160 as radio waves can be reduced.

FIG. 8 is a cross-sectional view showing another example of the structure of the transformer 160 in this embodiment.
In this example, a primary winding 161, a shield winding 163, and a secondary winding 162 are wound around an iron core 170 of a transformer 160 in order from the inside.
Thus, by winding the shield winding 163 between the primary winding 161 and the secondary winding 162, noise generated on the primary side of the power supply device 100 and generated on the secondary side of the power supply device 100. Noise can be separated.

In the power supply device 100 in this embodiment, the shield winding 163 of the transformer 160 is wound between the primary winding 161 and the secondary winding 162.
Primary noise and secondary noise can be separated, and an increase in noise level due to noise multiplication can be suppressed.

Embodiment 3 FIG.
The third embodiment will be described with reference to FIGS.
In addition, about the part which is common in the lighting fixture 800 demonstrated in Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

FIG. 9 is a block configuration diagram showing a functional block configuration of the lighting fixture 800 in this embodiment.
In addition to the functional blocks described in Embodiment 1, the lighting fixture 800 includes a protection detection circuit 195. The transformer 160 further has a bias winding 164.

  The protection detection circuit 195 detects a voltage generated at both ends of the bias winding 164 (hereinafter referred to as “bias winding voltage”), and generates a protection signal based on the detected bias winding voltage. The protection signal is a signal that stops the operation of the switching circuit 150 when the protection detection circuit 195 detects an abnormality. For example, the protection detection circuit 195 generates a protection signal when the bias winding voltage becomes abnormally high.

  The switching circuit 150 receives the protection signal generated by the protection detection circuit 195, and controls the conductive insulation of the switch based on the input protection signal. The switching circuit 150 determines whether or not the protection detection circuit 195 has detected an abnormality based on the input protection signal. If the protection detection circuit 195 determines that an abnormality has been detected, the switching circuit 150 continues to turn off the switch. State and stop operation.

In the output smoothing capacitor C82, the output smoothing anode terminal is electrically connected to the transformer fourth terminal 174 (one end of the secondary winding 162) of the transformer 160, and the output smoothing cathode terminal is electrically connected to the rectification anode terminal of the rectifying element D81. doing. The rectifying cathode terminal of the rectifying element D81 is electrically connected to the transformer fifth terminal 175 of the transformer 160 (the other end of the secondary winding 162). That is, as compared with the first embodiment, the connection order of the rectifying element D81 and the output smoothing capacitor C82 connected in series is reversed.
As a result, the current flowing from the primary winding 161 via the parasitic capacitance and the current flowing from the secondary winding 162 via the parasitic capacitance are in opposite phases and cancel each other, so that the shield winding 163 passes through the parasitic capacitance. The current that flows through the shield winding 163 may be small, and the number of turns of the shield winding 163 can be reduced.
Note that the rectifying element D81 and the output smoothing capacitor C82 may be connected in the same order as in the first embodiment.

FIG. 10 is a cross-sectional view showing the structure of the transformer 160 in this embodiment.
In this example, a shield winding 163, a primary winding 161, a bias winding 164, and a secondary winding 162 are wound around the iron core 170 of the transformer 160 in order from the inside.
Thus, when the winding wound around the iron core 170 is other than the primary winding 161, the secondary winding 162, and the shield winding 163, the fourth winding (bias winding 164) is used. By winding between the primary winding 161 and the secondary winding 162, both the effect of the shield winding 163 described in the first embodiment and the effect of the shield winding 163 described in the second embodiment are enjoyed. can do. That is, noise leaking to the outside from the power supply line can be reduced, and noise generated on the primary side of the power supply apparatus 100 and noise generated on the secondary side can be separated.

FIG. 11 is a cross-sectional view showing another example of the structure of the transformer 160 in this embodiment.
In this example, a bias winding 164, a primary winding 161, a secondary winding 162, and a shield winding 163 are wound around the iron core 170 of the transformer 160 in order from the inside. In this way, the bias winding 164 is wound on the innermost side instead of the shield winding 163 described in the first embodiment, and the shield winding 163 is wound on the outermost side in the same manner as described in the second embodiment. Thus, noise leaking from the power supply line to the outside can be reduced, and noise coupled to an external circuit can be reduced.

FIG. 12 is a cross-sectional view showing still another example of the structure of the transformer 160 in this embodiment.
In this example, a primary winding 161, a bias winding 164, a secondary winding 162, and a shield winding 163 are wound around the iron core 170 of the transformer 160 in order from the inside.
As described above, of the two types of shield windings 163 described in the second embodiment, one is replaced with the bias winding 164 and the other is the shield winding 163, thereby reducing noise radiated to the outside. In addition, the noise generated on the primary side of the power supply apparatus 100 and the noise generated on the secondary side can be separated.

  Further, instead of or in addition to the bias winding 164, a power supply winding for obtaining a power supply of an IC constituting the switching circuit 150 or the like may be provided in the transformer 160.

FIG. 3 is a block configuration diagram showing a functional block configuration of the lighting fixture 800 in the first embodiment. FIG. 2 is a plan view and a cross-sectional view taken along line AA showing the structure of the transformer 160 in the first embodiment. FIG. 3 is an electric circuit diagram illustrating a circuit configuration of an inrush current suppression circuit according to the first embodiment. FIG. 3 is a waveform diagram showing voltages and currents of each part of power supply device 100 according to the first embodiment. FIG. 5 is a frequency characteristic diagram showing the experimental results of noise leaking to the AC power supply AC side in power supply device 100 according to the first embodiment. The frequency characteristic figure which shows the experimental result of the noise which leaks to the alternating current power supply AC side when the shield winding 163 is wound only to half as a reference example. Sectional drawing which shows the structure of the transformer 160 in Embodiment 2. FIG. Sectional drawing which shows another example of the structure of the transformer 160 in Embodiment 2. FIG. FIG. 10 is a block configuration diagram showing a functional block configuration of a lighting fixture 800 in Embodiment 3. Sectional drawing which shows the structure of the transformer 160 in Embodiment 3. FIG. Sectional drawing which shows another example of the structure of the transformer 160 in Embodiment 3. FIG. Sectional drawing which shows the further another example of the structure of the transformer 160 in Embodiment 3. FIG.

Explanation of symbols

  100 power supply device, 110 noise filter circuit, 120 rectifier circuit, 130 inrush current suppression circuit, 135 voltage dividing circuit, 150 switching circuit, 160 transformer, 161 primary winding, 162 secondary winding, 163 shield winding, 164 bias winding Wire, 170 iron core, 171 transformer first terminal, 172 transformer second terminal, 173 transformer third terminal, 174 transformer fourth terminal, 175 transformer fifth terminal, 190 output detection circuit, 195 protection detection circuit, 800 lighting fixture, 810 LED circuit, AC AC power supply, C41 input smoothing capacitor, C82 output smoothing capacitor, D33, D81 rectifier, R31 current limiting element, R36, R37 resistance, T32 switching element.

Claims (5)

An input smoothing capacitor; an inrush current suppressing circuit for suppressing an inrush current flowing through the input smoothing capacitor; a transformer that applies an input smoothing voltage charged to the input smoothing capacitor to a primary winding; and a secondary winding of the transformer. In a power supply device having an output smoothing capacitor charged by a secondary voltage generated in a line,
The transformer has a shield winding having one end electrically connected to one end of the primary winding,
The shield winding is wound on the innermost side among the shield winding, the primary winding and the secondary winding,
The inrush current suppression circuit controls suppression of the inrush current based on a shield winding voltage generated at both ends of the shield winding. The shield winding is wound in a direction in which the shield winding voltage becomes positive when the input smoothing voltage is applied to the primary winding,
The inrush current suppression circuit is electrically connected in series with the input smoothing capacitor and in parallel with the current limiting element, and is electrically connected in parallel when the shield winding voltage becomes higher than a predetermined voltage. The power supply device according to claim 1 , further comprising: a switching element that performs switching. The inrush current suppression circuit has a rectifying element for half-wave rectifying the shield winding voltage, and a voltage dividing circuit for resistance-dividing the voltage rectified by the rectifying element,
The power supply device according to claim 2 , wherein the switching element is turned on when a voltage obtained by resistance-dividing the voltage dividing circuit is higher than a predetermined voltage. The transformer has an iron core, the transformer shield winding, a power supply device according to any one of claims 1 to 3, characterized in that they are more wound in the iron core. A power supply device according to any one of claims 1 to 4, the voltage charged in the smoothing output capacitor, lighting equipment, characterized in that the light source lights.

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