JP2012147626A - Power supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress power consumption of an AC input by lowering a voltage after AC input voltage smoothing to be supplied to a converter in a low power consumption state, thereby lowering the voltage supplied to the converter for suppressing switching loss.SOLUTION: When ON time of a switching element by switching means is shortened while an output current load from a converter by a switching system is lowering in a low power consumption state, charging selection means selects no charging into a smoothing means. When ON time of the switching element by switching control means is lengthened with the voltage of the smoothing means lowered, the charging selection means selects charging into the smoothing means.

Description

  The present invention relates to a power supply device that is insulated from a primary side and a secondary side by a transformer and transmits electric power to a secondary side by a switching operation on the primary side. For example, a power supply device that receives AC 100 V AC from a commercial power source, converts it to DC voltage by rectification and smoothing, and transmits power to the secondary side via the switching transformer by the switching operation on the primary side. Can do.

  A power supply device is an AC-DC converter that converts an alternating voltage from an AC line to generate a DC voltage, and supplies it to other devices or connected units. A switching method is widely used for an AC-DC converter that converts an AC input voltage into a DC and outputs it. These devices may use a switching transformer configured in combination with a core material so that an input and an output are magnetically coupled by a primary side winding and a secondary side winding. The winding is used for the switching transformer as described above, and an insulating film is added to a conductive material such as a copper wire. The primary and secondary windings are insulated. Some power supply apparatuses operate the converter in a low power consumption state at a light load with a small DC output current. In addition, there is a type that operates a converter corresponding to a heavy load at a heavy load with a large DC output current. When the load is light, the unit that is connected to the power supply unit is put into standby mode that is in standby state or sleep mode that is in low power consumption state, and when multiple converters are connected, the operation of the converter that can be stopped is stopped There is also.

  As a method of putting the converter into a low power consumption state, as in Patent Document 1, the voltage applied to the converter is partially changed by switching the voltage after full-wave rectification without rectifying and smoothing the AC voltage. A method for reducing and reducing power loss is disclosed. Further, as disclosed in Patent Document 2, it has a circuit configuration for detecting an energy saving mode in a low power consumption state and an intermittent pulse generation circuit for setting a voltage application timing to the smoothing capacitor, and the necessity for supply to the smoothing capacitor In some cases, a smoothing voltage in a smoothing capacitor is set in combination with a circuit configuration for detecting the power supply, and the power supply is switched on / off to configure a power supply in a low power consumption state. Further, as disclosed in Patent Document 3, only a unit that operates in a low power consumption state is supplied with power, and a means that can be charged is provided on the secondary side of the converter. A configuration for turning on / off power supply to the converter is also disclosed.

JP-A-7-284269 JP 2001-224132 A Japanese Patent Laid-Open No. 2001-251853

  However, in the above-mentioned conventional example, in Patent Document 1, when the voltage after full-wave rectification from the AC input is not smoothed by the primary smoothing capacitor in the low power consumption state, switching is performed near the peak voltage depending on the switching timing. Sometimes. At that time, there is a problem in that there is a period in which the power loss, which is the product of the current and voltage supplied to the switch element, increases and the power consumption increases. In addition, Patent Document 2 has an intermittent pulse generation circuit that operates with power supplied from an AC input, an energy saving mode detection circuit, and a supply mode detection circuit for a smoothing capacitor, which has a problem in that the circuit configuration is complicated. . Moreover, in patent document 3, when performing the control in the low power consumption mode, the voltage of the charging unit configured in the secondary unit is monitored and fed back to the primary unit, which increases the cost. It is.

  In some cases, energization to an AC load connected to the AC line may be controlled with reference to a zero cross timing at which the AC voltage of the AC line is around 0V. For example, the load may include power supply for charging the primary smoothing capacitor.

  However, in Patent Documents 2 and 3, the zero-crossing timing is not considered at the timing of starting charging of the primary smoothing capacitor in the low power consumption mode, and there is a sudden change in current around the outlet that is the AC power supply source. A voltage drop in the AC line may occur, affecting other devices connected to the same AC line.

  Accordingly, an object of the first invention according to the present application is to reduce the switching loss by reducing the voltage supplied to the converter by reducing the voltage after smoothing the AC input voltage supplied to the converter in a low power consumption state. An object of the present invention is to provide a power supply device with reduced power consumption of AC input.

  Also, the object of the second invention is to turn on / off the power supply from the AC line in synchronization with the zero cross timing of the AC input voltage, to prevent voltage fluctuation due to sudden current fluctuation of the AC line and to reduce the smoothing voltage. It is another object of the present invention to provide a power supply apparatus that reduces switching loss by reducing the voltage supplied to the converter and reduces the power consumption of the AC input.

  The third invention is also directed to supply power continuously from the AC line to the smoothing means in order to supply power from the corresponding converter at heavy load when the DC output current becomes large, and zero crossing of the AC input. It is an object of the present invention to provide a power supply apparatus that can supply power from an AC line in synchronization with timing and prevent voltage fluctuation due to sudden current fluctuation of the AC line.

  In order to achieve the above object, a first invention according to the present application includes a switching control unit that controls a switching element of a converter by a switching method, and a smoothing that rectifies an input from an AC commercial power source, charges the capacitor, and smoothes it. Charging means for switching charging to the smoothing means, and charging selection means for switching whether or not to charge the smoothing means with the charge switching means according to an ON time in a switching cycle, When the ON time of the switching element by the switching means is shortened when the output current load is reduced, the charging selection means selects that the smoothing means is not charged, and the voltage of the smoothing means decreases to reduce the switching control means. When the ON time of the switch element due to is increased, the charging selection means charges the smoothing means. It is characterized by selecting.

  Further, according to a second aspect of the present invention, in the power supply device of the first aspect, when the output current load is reduced, when the on-time of the switching element by the switching unit is shortened, the charge selection unit performs the smoothing unit. If the voltage of the smoothing means decreases and the ON time of the switch element by the switching control means becomes long, the charging selection means selects to charge the smoothing means, and the AC voltage The smoothing means is charged in synchronism with zero-cross timing.

  According to a third aspect of the present invention, in the power supply device according to the first and second aspects of the present invention, when the output current load from the converter increases, the smoothing means is charged. And

  As described above, according to the first invention, the smoothed voltage of the AC input voltage supplied to the converter in the low power consumption state is lowered to reduce the switching loss, thereby reducing the power consumption of the AC input. It becomes possible.

  Further, according to the second invention, the power supply from the AC line is turned on or off in synchronization with the zero cross timing of the AC input voltage, voltage fluctuation due to sudden current fluctuation of the AC line can be prevented, and the low power consumption state Thus, it is possible to reduce the switching loss by reducing the smoothed voltage of the AC input voltage supplied to the converter, and to reduce the power consumption of the AC input.

  Further, according to the third aspect of the invention, it is possible to cope with an increase in the output current load by charging the smoothing means in response to the operation of the converter in which the output current load increases. Power can be supplied from the AC line in synchronization with the zero cross timing, and voltage fluctuations due to sudden current fluctuations in the AC line can be prevented.

The figure showing the circuit block of the power supply device which concerns on the Example of this invention. The figure showing the circuit structure of the power supply device which concerns on the Example of this invention. The figure showing the signal in the circuit structure of the power supply device which concerns on the Example of this invention. The figure showing the signal in the circuit structure of the power supply device which concerns on the Example of this invention. The figure showing the signal in the circuit structure of the power supply device which concerns on the Example of this invention. The figure showing the signal in the circuit structure of the power supply device which concerns on the Example of this invention. The figure showing the loss of the switch element in the circuit structure of the power supply device which concerns on the Example of this invention. The figure showing the signal in the circuit structure of the power supply device which concerns on the Example of this invention. The flowchart showing operation | movement of the power supply device which concerns on the Example of this invention.

[Example 1]
A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a power supply device according to an embodiment of the present invention and a configuration of a load connected to the power supply device.

  Reference numeral 1 denotes an AC (alternating current) power source such as a commercial power source, and reference numeral 2 denotes a rectification control unit that controls whether or not the AC input is rectified. Reference numerals 3 and 4 denote an AC controller 1 (AC CTRL1) and an AC controller 2 (AC CTRL2) for switching whether or not the AC input is supplied to a bridge rectifier circuit 5 such as a bridge diode and the primary smoothing capacitor 6 is charged as a DC voltage. is there. Reference numeral 11 denotes a converter (CNV1) that generates a voltage Vcc1 by stepping down a DC voltage using a switching method. A converter (CNV2) 12 steps down the above-described DC voltage to generate Vcc2. The AC controller 1-3 is operated by the output from the converter 11, and the AC controller 2-4 is operated by the output from the converter 12.

  A zero cross signal output unit 13 detects the zero cross timing of the voltage from the AC power source 1 and outputs a ZRX signal. Reference numeral 14 denotes a CPU (Central Processing Unit) which inputs the ZRX signal from the zero cross signal output unit 13 and sets the operation timing and controls the AC load 15 to be controlled. The CPU 14 also controls the operation of the DC loads 16 and 17 and the DC circuit. Reference numeral 14a denotes a ROM (Read Only Memory) installed in the CPU 14, in which the content of control by the CPU 14 is recorded, and processing is executed in the CPU 14 based on the content. Reference numeral 14b denotes a RAM (Random Access Memory), which has a memory area used for temporary storage of data and processing in the processing of the CPU 14.

  Power lines AC_H and AC_L from an AC supply source are connected to the AC load 15 and are controlled by the CPU 14. The energization of the AC load 15 reduces the inrush current by energizing when the AC voltage is approximately zero volts, and controls the energization timing based on the ZRX signal from the zero cross signal output unit 13.

  Reference numerals 16 and 17 denote DC loads and DC circuits using Vcc2 as a power source, and are controlled by the CPU 14. For example, a drive unit such as a DC motor or a sensor unit that operates with a DC power source.

  Reference numeral 18 denotes a SW (switch) that can select whether or not to output the Vcc1 voltage from the converter 11 by a user operation.

  Power is supplied from the converter 11 to the converter 12 as IC Vcc, and zero-cross signal generation power ZRX_PS is supplied from the converter 12 to the zero-cross signal output unit 13.

  FIG. 2 is a diagram illustrating a circuit configuration of the power supply device according to the embodiment of the present invention.

  Reference numeral 7 denotes a choke coil, which is installed on the AC_N line in order to reduce a rapid current fluctuation of the AC line.

  Reference numeral 102 denotes a power supply IC that controls the switching operation of the converter 11. In the present embodiment, the power supply IC is taken as an example, but there is a method in which components are combined individually. The power supply IC 102 performs on / off control of the switch element 103. The power supply IC 102 is activated by supplying power from the AC_H line connected to the ST terminal. In this embodiment, a MOSFET is taken as an example of a switching element for switching operation, but is not particularly limited. A capacitor 104 is connected between the drain and source terminals of the MOSFET which is the switch element 103. Reference numeral 105 denotes a current detection resistor connected to the switch element 103. It is used to detect the current when the switch element 103 is on and to control the on / off switching timing in the power supply IC 102.

  106 (106a, 106b, 106c) is a switching transformer. Reference numeral 106a denotes a primary main winding. The voltage between DC_H and DC_N after rectification is applied by the switch element 103 controlled by the power supply IC 102. Reference numeral 106b denotes a secondary output Vcc1 output winding. An auxiliary winding 106 c supplies operating power to the power supply IC 102. It is assumed that the 102 power supply IC performs switching after activation from the ST terminal described above and continues the operation by the output from 106c. Reference numeral 106 c is connected to the power supply IC 102, and is used to detect the timing when the power supply IC 102 turns on the switch element 103.

  107a and 107b diodes are diodes for half-wave rectification of the output from the auxiliary winding 106c, and 108a and 108b are smoothing capacitors. The smoothed voltages are IC Vcc1 and IC Vcc2.

  The diode 109 is a diode that rectifies the output from the winding 106b, and 110a and 110b are smoothing capacitors. The smoothed voltage is output as Vcc1 when the FET 19 is turned on while the SW (switch) 18 installed on the secondary side is turned on. In the OFF state of SW18, the output of Vcc1 is stopped by turning off FET19. Reference numeral 111 denotes a choke coil that reduces sudden current fluctuations in the smoothing capacitor 110b.

  In this embodiment, the photocoupler 112, the shunt regulator 113, and the resistors 114 and 115 show the configuration of a voltage feedback (feedback) circuit for stabilizing the potential of Vcc1. In addition, the photocoupler 112 insulates and separates the primary side and the secondary side, and the voltage output state of Vcc1 from the secondary side to the power supply IC 102 on the primary side via the FB signal line depending on the light emitting state of the light emitting unit. This is transmitted to the power supply IC 102. With respect to the voltage feedback circuit of Vcc1, the method and configuration are not particularly limited.

  A power supply IC 119 controls the switching operation of the converter 12. The 119 power supply IC performs on / off control of the 120 switch elements. In this embodiment, a MOSFET is taken as an example of the switch element, but is not particularly limited. Reference numeral 121 denotes a capacitor connected between the drain and source terminals of the MOSFET of the switch element 120. Reference numeral 122 denotes a current detection resistor connected to the switch element 120. A current at the time of switching of the switch element is detected, and the power supply IC 119 is used to control the switching timing.

  123 (123a, 123b, 123c) is a switching transformer. Reference numeral 123a denotes a primary main winding. The voltage between DC_H and DC_N after rectification is applied by the switch element 120 controlled by the power supply IC 119. Reference numeral 123b denotes a secondary output Vcc2 output winding. An auxiliary winding 123c is connected to the power supply IC 119. The power supply IC 119 is connected to detect the timing when the switch element 120 is turned on.

  The diode 124 is a diode that rectifies the output from the winding 123b, and 125a and 125b are smoothing capacitors. The smoothed voltage becomes Vcc2.

  Reference numeral 126 denotes a choke coil that reduces a rapid current fluctuation to the smoothing capacitor 125b.

  Reference numeral 127 denotes a switch element that switches whether the IC Vcc2 is supplied to the power supply IC 119 as operating power or stopped. At the same time, the zero-cross signal output unit 13 is switched to supply or stop the zero-cross signal generation power as ZRX_PS. In this embodiment, 127 uses a MOSFET, but is not particularly limited.

  A photocoupler 128 insulates and separates the primary side and the secondary side of the converter 12 and controls the switch element 127.

  The photocoupler 129, the shunt regulator 130, and the resistors 131 and 132 are voltage feedback circuits for stabilizing the potential of Vcc2. In addition, the photocoupler 129 insulates and separates the primary side and the secondary side, and the voltage output state of Vcc2 from the secondary side via the FB signal line of the power supply IC 120 on the primary side depending on the light emission state of the light emitting unit. To the power supply IC 119. With respect to the voltage feedback circuit of Vcc2, the method and configuration are not particularly limited.

  Reference numeral 133 denotes a switch element. When Vcc1 is output while the SW 18 is on, the switch element 133 switches between the operation of the converter 12 and the power supply to the zero-cross signal output unit 13 by the / CNV2_ON signal from the CPU 14. When the / CNV2_ON signal is in the Low state, the switch element 133 is turned on, the light emitting element of the photocoupler 128 is energized, and the switch element 127 is turned on. In addition, zero-cross signal generation power ZRX_PS is supplied to the zero-cross signal output unit 13. Further, the IC Vcc2 is supplied as operating power to the power supply IC 119, and the power supply IC 119 operates to output Vcc2.

  In the off state of SW18, the Vcc1 output is stopped, the energization of the light emitting element of the photocoupler 128 is stopped, the switch element 127 is turned off, the supply of IC Vcc2 to the power supply IC119 is stopped, and the power supply IC119 is stopped. , The output of Vcc2 is stopped. At the same time, the zero cross signal generation power ZRX_PS to the zero cross signal output unit 13 is stopped.

  Reference numeral 139 denotes a diode, which generates a half wave of the AC_N line voltage of the AC power supply, supplies a voltage to the switch element 141 via the resistor 140, and generates an on or off state. When the switch element 141 is in the on state, the light emitting element of the photocoupler 142 is in the off state, and the ZRX signal is in the high state and is output to the CPU 14. When the switch element 141 is in the off state, the light emitting element of the photocoupler 142 is in the on state, and the ZRX signal is in the low state and is output to the CPU 14. The switching timing of the High and Low of the ZRX signal is a timing of crossing 0V of the AC voltage, and the CPU 14 inputs the zero cross signal ZRX. The CPU 14 detects this switching point and controls the energization timing of the AC power of the AC load 15 shown in FIG. 1 as zero cross timing.

  150 in the rectification control unit 2 is a triac, and is installed on the AC_H line of the AC power source. This is an element that switches between connection and disconnection of the AC voltage on the AC_H line, and whether or not the bridge rectifier circuit 5 is energized to charge the smoothing capacitor 6 as a DC voltage. The average loss when the triac 150 is energized is smaller than the average loss that occurs when the switch elements 103 and 120 are turned on and off.

Reference numeral 151 denotes a noise absorbing element that absorbs voltage fluctuations when the triac 150 is turned on and off. Reference numeral 152 denotes a phototriac coupler, which is an element that performs switching control to turn on or off the triac 150 in accordance with the light emission side control.
The AC controller 1 (AC CTRL1) 3 operates to convert an output voltage from the OUT of the power supply IC 103 of the converter 11 (CNV1), and includes diodes 153 and 158, a capacitor 155, resistors 154 and 156, and a constant voltage diode 157. It is configured. When the output load of the converter 11 increases, the ON output time from OUT of the power supply IC 103 becomes longer as shown in the upper diagram of FIG. Therefore, the output voltage of AC CTRL1 is filtered by the resistor 154 and the capacitor 155 via the diode 153, and is output with a voltage equal to or higher than the Zener voltage Vz1 of the constant voltage diode 157 and by the forward voltage of the diode 158. The AC CTRL1 output voltage waveform becomes the voltage output waveform shown in the lower diagram of FIG. 3, and the light emitting element of the phototriac coupler 152 emits light. However, the waveform of the AC CTRL1 output voltage waveform changes due to the voltage drop of the light emitting element of the phototriac coupler 152, but the waveform after the change is not shown in FIG. 3 of the present embodiment. Further, when the voltage of the primary smoothing capacitor 6 decreases with respect to the output load, the switching on time becomes long so that the power supply from the primary side and the power of the output load on the secondary side are balanced. The on output time from OUT of the IC 103 becomes longer.

  FIG. 4 shows the state of the switch element 103 in a state where the ON output time from OUT is long and the ON time of the switch element 103 is long. The upper diagram shows the drain-source voltage Vds of the switch element 103 that is a MOSFET, and the drain current Id is as shown in the following diagram. Further, as a condition for increasing the ON time, it corresponds to a case where the charging voltage of the primary smoothing capacitor 6 is low, and it becomes possible to turn on the switch element 103 with a low Vds voltage. Therefore, the discharge voltage from the capacitor 104 can be reduced, and the product of Vds and Id, which is a loss when the switch element 103 is turned on, can be reduced. As the loss of the switch element 103 is smaller, the power consumption, which is the input power from the AC power supply, is smaller and the efficiency is improved.

  When the output load of the converter 11 is reduced, the ON output time from the OUT of the power supply IC 103 is shortened as shown in the upper diagram of FIG. Therefore, the output voltage of AC CTRL1 is filtered by the resistor 154 and the capacitor 155 via the diode 153, and is output by dropping the voltage equal to or higher than the voltage of the constant voltage diode 157 and by the forward voltage of the diode 158. Then, the voltage output waveform shown in the lower diagram of FIG. 5 is obtained, and the light emission time of the light emitting element of the phototriac coupler 152 is shortened.

  FIG. 6 shows the state of the switch element 103 when the ON output time from OUT is short and the switch element 103 has a short on time. The upper diagram shows the drain-source voltage Vds of the switch element 103 that is a MOSFET, and the drain current Id is as shown in the following diagram. Further, as a condition for shortening the ON time, it corresponds to a case where the charging voltage of the primary smoothing capacitor 6 is high, and the switch is turned on when the Vds voltage of the switch element 103 is high. For this reason, the discharge voltage from the capacitor 104 increases, and the product of Vds and Id, which is a loss when the switch element 103 is on, increases.

  As the loss of the switch element 103 increases, the power consumption, which is the input power from the AC power supply, increases and the efficiency is lowered.

  If the voltage at which the light-receiving side conduction state changes by the light emitting element of the phototriac coupler 152 is Vth, the light emission time of the phototriac coupler 152 varies depending on the voltage output of AC CTRL1 shown in FIGS. When the ON output time from OUT is increased so as to increase the switching ON time as shown in FIG. 3, the conduction time of the phototriac coupler 152 is increased. When the switching on time is short as shown in FIG. 5, the conduction time is shortened.

  The AC controller 2 (AC CTRL2) 4 also operates in the same manner as the AC controller 1-3, operates to convert the OUT output of the power supply IC 120 of the converter 12 (CNV2), diodes 160 and 165, a capacitor 162, and a resistor 161 and 163 and a constant voltage diode 164.

The AC controller 1-3 and the AC controller 2-4 are OR-connected by diodes 158 and 165, and according to the switching state of either the converter 11 or the converter 12, the light emitting element of the phototriac coupler 152 is energized, By turning on or off 150, the charging or discharging state of the primary smoothing capacitor 6 is set.
When the output load of either the converter 11 or the converter 12 increases, the on-time of the triac 150 becomes longer and the voltage of the primary smoothing capacitor 6 increases. For example, when the current load of the DC load 16 or 17 in FIG. 1 increases, the on-time of the triac 150 is increased following the change in the load state, and the voltage of the primary smoothing capacitor 6 is increased. It operates to correspond to the conversion of power from the side to the secondary side.

  When the output load is light, the time for the OUT output of the power supply IC 103 or the OUT output of the power supply IC 120 is shortened, and the energization time of the light emitting element of the phototriac coupler 152 is shortened. When the light emitting element of the phototriac coupler 152 is turned off, the triac 150 is turned off, and the voltage is lowered because the primary smoothing capacitor 6 is not charged.

  FIG. 7 is a diagram showing the input voltage from the AC power source and the average loss Pd of the switch element 103. When the AC input voltage is high, the voltage between DC_H and DC_N after rectification is high, and the switch element 103 is turned on with a high Vds voltage. Therefore, the discharge voltage from the capacitor 104 increases, and the loss Pd of the switch element 103 increases.

  Conversely, when the voltage between DC_H and DC_N after rectification is low, the discharge voltage from the capacitor 104 is low, and the loss Pd of the switch element 103 is small.

  By reducing the loss of the switch element 103, the input power from the AC power source can be reduced, and the power consumption of several percent can be reduced.

  FIG. 8 shows the voltage of the primary smoothing capacitor 6 and the voltage output waveform of AC CTRL1 when the output load is light. When the primary smoothing capacitor 6 is charged, the output time of OUT output is shortened, and the triac 150 is turned off. Due to the discharge of the primary smoothing capacitor 6, the output time of the OUT output of the power supply IC 103 changes from a short state to a long state over time. Therefore, when the output voltage of AC CTRL1 rises and becomes equal to or higher than the voltage Vth at which the light-receiving side conduction state is changed by the light emitting element of the phototriac coupler 152, the triac 150 is turned on. After that, when the primary smoothing capacitor 6 is charged and the high output time of the OUT output of the power supply IC 103 becomes short, the phototriac coupler 152 is changed from the on state to the off state, and the triac 150 is turned off. Thereafter, the ON state and the OFF state of the triac 150 are repeated, and the charging state and the discharging state of the primary smoothing capacitor 6 are repeated.

  FIG. 9 is a flowchart showing the operation of the power supply device according to the first embodiment of the present invention. The operation will be described with reference to the circuit of FIG.

  In S100, electric power is input from an alternating current (AC) power supply 1 such as a commercial power supply, and in S101, the 102 power supply IC of the converter 11 is activated to start a switching operation.

  If the output of the AC controller 1 (AC CTRL1) 3 or the AC controller 2 (AC CTRL2) 4 is output by the OUT output of the 102 power supply IC in S102 and the phototriac coupler 152 becomes conductive, the process proceeds to S103. In S103, when the triac 150 is turned on, the primary smoothing capacitor 6 is charged with the DC voltage via the five rectifier circuit. If there is no output from the AC controller 1-3 and AC controller 2-4 in S102, the triac 150 is not conducted and the primary smoothing capacitor 6 is discharged. If the switch (SW) 18 is on in S105, the process proceeds to S106, and if it is off, the process proceeds to S119.

  If the 18 switch is turned on, the FET 19 of the switch element is turned on in S106, and the Vcc1 voltage is output in S107. The Vcc1 voltage is supplied to the CPU 14 and the power supply circuit. The CPU 14 can operate by being supplied with Vcc1, and after the RAM 14b is initialized by the control program in the ROM 14a shown in FIG. 1, the AC load 15 and the DC loads 16, 17 are controlled. . Further, the state transition to the normal operation state or the low power consumption mode is determined according to the control state of the AC load 15 or the DC loads 16 and 17 connected to the power supply apparatus. Also, output control of the / CNV2_ON signal is performed.

  In S108, when the CPU 14 is set to the low power consumption mode, the switch element FET 133 is turned off in S110 in order to stop the operation of the converter 12 (CNV2) by setting the / CNV2_ON signal to the High state. In S111, the photocoupler 128 is turned off, and in S112, the 119 power IC is stopped. In S113, the output of Vcc2 is stopped.

  If the power consumption is not low in S108, the converter 133 (CNV2) is operated in S114 by setting the / CNV2_ON signal to the low state, and the FET 133 is turned on in S115. Next, it is shown that the 128 photocoupler is turned on in S116, the power supply IC 119 operates in S117, and Vcc2 is output in S118.

  If the 18 switch is off in S105, the FET 19 is turned off in S119, and the Vcc1 output is stopped in S120. Next, the FET of the switch element 133 is turned off in S121, the photocoupler 128 is turned off in S122, the power supply IC 119 is stopped in S123, and the output of Vcc2 is stopped in S124.

  These steps from S102 to S124 are repeatedly executed.

  As described above, in the present invention shown in FIGS. 1 to 9, the on-time of the switching element in switching of the converter varies depending on the load state of the DC output and the voltage charged in the primary smoothing capacitor. . In particular, by reducing the smoothed voltage of the AC input supplied to the converter in a low power consumption state, the switching loss is reduced, and the power consumption of the AC power input can be reduced.

[Example 2]
A second embodiment of the present invention will be described below with reference to the drawings. FIG. 2 described above is a diagram illustrating a circuit configuration of the power supply device according to the embodiment of the present invention. In FIG. 2, in the phototriac coupler 152, when the triac 150 is turned on, the light receiving side element is energized. The timing at which this energization state is set is the zero cross timing of the AC_H line voltage of the AC power supply. Thus, when the triac 150 is turned on, the phototriac coupler 152 is of a zero cross detection type so that the triac 150 is turned on in the vicinity of 0 V of the AC voltage. By charging the primary smoothing capacitor 6 at the zero-cross timing, the inrush current can be reduced, the power loss of the triac 150 and the rectifier circuit 5 and the rapid voltage fluctuation of the AC power supply line without any sudden current fluctuation Can be prevented.

  As described above, voltage fluctuation due to abrupt current fluctuations in the AC power supply line can be prevented, the voltage after smoothing of the AC input supplied to the converter in the low power consumption state is reduced, switching loss is reduced, and AC input is reduced. Power consumption can be reduced

DESCRIPTION OF SYMBOLS 1 ... Commercial alternating current (AC) power supply 2 ... Rectification control part 3, 4 ... AC controllers 1 and 2 (AC CTRL1, AC CTRL2)
5. Rectifier circuit (bridge diode)
6. Primary smoothing capacitor 11. Converter (CNV1)
12 ... Converter (CNV2)
13 ... Zero-cross signal output unit 14 ... Central processing unit (CPU)
15 ... AC load 16, 17 ... DC load 18 ... Switch (SW)
103, 120 ... Power supply IC
104, 121 ... Switch element (MOSFET)
106, 123 ... Switching transformer 112, 129, 128, 142 ... Photocoupler 141 ... Switching element (transistor)
150 ... Triac 152 ... Photo triac coupler (zero cross detection type)

Claims (3)

Switching control means for controlling a switching element of the converter by a switching method;
Smoothing means for rectifying the input from the AC commercial power supply, charging the capacity and smoothing,
Charge switching means for switching charging to the smoothing means;
Charging selection means for switching whether to charge or not to charge to the smoothing means according to the ON time in the switching cycle,
When the on-time of the switching element by the switching means is shortened when the output current load is reduced, the charging selection means selects not to charge the smoothing means,
When the voltage of the smoothing means decreases and the ON time of the switching element by the switching control means becomes long, the power selection device selects that the smoothing means is charged by the charge selection means. When the on-time of the switching element by the switching means is shortened when the output current load is reduced, the charging selection means selects not to charge the smoothing means,
When the voltage of the smoothing means decreases and the on time of the switch element by the switching control means becomes long, the charging selection means selects to charge the smoothing means,
The power supply apparatus according to claim 1, wherein the smoothing unit is charged in synchronization with a zero-cross timing of an AC voltage. 3. The power supply device according to claim 1, wherein when the output current load from the converter increases, the smoothing unit is charged.