JP2008199731A - Power supply unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent flickering of a lighting device connected in parallel with a power supply unit for supplying a switching load with operating power. <P>SOLUTION: The power supply unit 1 for supplying power to a switching load 20 comprises a rectifier circuit 2 for rectifying an AC voltage, a first boost converter 6 performing switching control of rectified output voltage from the rectifier circuit 2 and charging a first capacitor C1, a second boost converter 3 performing switching control of rectified output voltage from the rectifier circuit 2 and charging a second capacitor C2, and a DC/DC converter 5 for controlling the charging voltage of the first capacitor C1 to produce a DC voltage being supplied to the switching load 20 wherein the second boost converter 3 has a discharge circuit for inputting the charges stored in the second capacitor C2 during off period of the switching load 20 to the DC/DC converter 5 during on period of the switching load 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power supply apparatus including switching control means for suppressing power supply voltage fluctuations caused by a load that intermittently requires a large current.

  Various devices are connected to the distribution line that supplies power from a commercial AC power source together with lighting devices. These various devices include devices having a characteristic that a large current flows intermittently. For example, as shown in FIG. 8, a switching load 101 that requires a relatively large intermittent current and an illumination device 102 such as a light bulb or a fluorescent lamp are connected to the distribution line, and the switching load 101 is turned ON / OFF. Is repeated, the current flowing through the distribution line also fluctuates correspondingly, so that the voltage drop due to the impedance of the distribution line fluctuates. Thereby, the voltage applied to the lighting device 102 also varies. As the switching load 101, for example, a page printer requires a large amount of power during transfer and fixing, and this state is performed each time paper is fed, and the current is repeatedly turned on and off at a cycle corresponding to the printing speed.

  FIG. 9 shows the input voltage, the current on the AC power supply side before full-wave rectification, and the state of rest and operation of the switching load 101 with respect to the switching load 101 obtained by full-wave rectification of the three-phase AC voltage. The AC input current in the operating state of the switching load 101 flows at a timing when the full-wave rectified voltage is equal to or higher than a predetermined value, and the AC input current in the rest state is almost zero. Accordingly, the input voltages of the switching load 101 and the lighting device 102 rise when the switching load 101 is in a resting state. Such a voltage fluctuation occurs due to repetition of operation and pause of the switching load 101, and flickering of lighting occurs due to fluctuation of the input voltage to the lighting device 102 such as a fluorescent lamp.

  Regulations on this flickering of lighting are about to be implemented. For example, flicker standards according to IEC (International Electrotechnical Commission) 1000-3-3 and IEC 1000-3-11 are known.

  The printer apparatus generally has a configuration in which a copied toner image is transferred to a sheet and fixed by heating, and a configuration in which fixing processing in that case is performed by heat generated by flash lamp emission is also known. The flash lamp in that case emits light for discharge, and a configuration is adopted in which the discharge current of the flash lamp is supplied from a capacitor that has been charged in advance. In such a case, a power supply device for charging with a DC voltage is required for the capacitor, and the AC voltage from the commercial AC power supply is rectified, and the switching is controlled so that the DC voltage becomes a predetermined value, and the capacitor is charged. The structure which performs is known (for example, refer patent document 1).

When a capacitor charging voltage is applied to the switching load and the capacitor is charged from the power supply device, the capacitor is not discharged during the rest period of the switching load, so that the current supplied from the power supply device is small. During the operation period of the switching load, the capacitor is periodically discharged, and the capacitor charging current is supplied from the power supply device. For this reason, as shown in FIG. 9, the input voltage fluctuates during the rest period and the operation period of the switching load, which causes flickering of the lighting apparatus connected to the same AC power source. Thus, a means for suppressing voltage fluctuation on the AC power supply side has been proposed by providing a control configuration in which the current from the AC power supply flows in the power supply device even during the suspension period of the switching load (see, for example, Patent Document 2).
JP 2004-129345 A Japanese Patent Laying-Open No. 2005-261061

  Various configurations such as single-phase 100V or 200V, single-phase three-wire 100V or 200V, and three-phase three-wire 200V are applied to the distribution line connected to the commercial AC power supply, and the distribution line is connected to the distribution line. The types and characteristics of equipment are often different. In this case, the lighting device can be regarded as a constant load when it is turned on, but other devices often have a variable load. In particular, in the case of the switching load 101 as shown in FIG. 8 described above, the load current changes intermittently, and the voltage changes depending on the impedance of the distribution line corresponding to the change. Therefore, there is a problem in that the applied voltage to the lighting device 102 connected to the distribution line fluctuates and flicker occurs.

  If the impedance of the distribution line is set to a small value that can be ignored, voltage fluctuation due to current fluctuation can be reduced. For this purpose, it is necessary to use a distribution line having a large diameter and to provide a large-capacity transformer. Therefore, it is not a practical solution in terms of economy and arrangement space. In general, a switching power supply device that can maintain a constant output voltage does not include a configuration that suppresses voltage fluctuation on the AC power supply (distribution line) side. The technology disclosed in Patent Document 2 described above suppresses voltage fluctuation on the AC power supply side due to a switching load as a configuration in which a charging current flows through the second capacitor during a switching load rest period. However, various configurations of the switching load have already been put into practical use, and the applied voltage is generally different depending on the type. Therefore, it is necessary to prepare a switching power supply device having a configuration corresponding to the voltage to be applied to the switching load, and there is a problem that costs increase due to multi-product production.

  An object of the present invention is to supply operating power to a switching load and prevent flickering of lighting equipment due to fluctuations in load current.

  A power supply apparatus according to the present invention is a power supply apparatus that supplies power to a switching load, and includes a rectifier circuit that rectifies an AC voltage, and a first capacitor that boosts a rectified output voltage of the rectifier circuit and charges the first capacitor. A boost converter, a second boost converter that boosts the rectified output voltage of the rectifier circuit and charges the second capacitor, and a DC voltage that supplies the charging voltage of the first capacitor to the switching load. A second DC / DC converter that controls the second boost converter in synchronization with the switching operation of the switching load, the charge that has charged the second capacitor during an operation OFF period of the switching load, A discharge circuit is provided for input to the DC / DC converter during an on-period of the switching load.

  The second boost converter is configured to control the charging current of the second capacitor based on information about the operation off of the switching load, and to stop charging the second capacitor based on the information about the operation on of the switching load. A circuit and control to apply the charge of the second capacitor to the DC / DC converter according to information on the operation on of the switching load, and to stop the discharge operation of the capacitor according to information about the operation off of the switching load device. And a discharging circuit for performing.

  The first boost converter for inputting the rectified output voltage of the rectifier circuit, the second boost converter for inputting the output voltage of the first boost converter, the first capacitor, and the second capacitor. And a DC / DC converter for inputting the charged charge.

  Further, in a power supply device that supplies power to a switching load, a rectifier circuit that rectifies an AC voltage, a boost converter that boosts the rectified output voltage of the rectifier circuit by on / off control of a switching transistor, and charges a capacitor; A DC / DC converter that controls the charging voltage of the capacitor to be a DC voltage supplied to the switching load, and the boost converter sequentially reduces the output reference voltage according to information on the operation of the switching load. A reference voltage output unit that sequentially increases an output reference voltage according to operation-off information, a comparator that compares an output reference voltage of the reference voltage output unit with a detection voltage that detects a terminal voltage of the capacitor, and the comparison Supply to the switching load via the comparator output signal and the DC / DC converter It comprises an error amplifier for inputting the detected current value detected flow, and a drive circuit for controlling the ON period of the switching transistor in accordance with the output signal of the error amplifier.

  Each of the first and second boost converters can output a set desired voltage by switching control. Therefore, the capacitor can be charged with a desired voltage corresponding to the type of switching load. In addition, the first capacitor is charged by the first boost converter, the charged charge is supplied to the switching load, and the second capacitor is charged by the second boost converter during the idle period of the switching load. Changes in the current supplied from the AC power supply so that the current from the power supply continuously flows and the charge of the second capacitor is supplied to the switching load during the operation period together with the charge of the first capacitor. Can be reduced to suppress voltage fluctuations, thereby preventing flickering of lighting equipment.

  Referring to FIG. 1, the power supply device of the present invention is a power supply device 1 that supplies power to a switching load 20. The power supply device 1 rectifies an AC voltage, and boosts the rectified output voltage of the rectifier circuit 2. The first boost converter 6 that charges the first capacitor C1, the second boost converter 3 that boosts the rectified output voltage of the rectifier circuit 2 and charges the second capacitor C2, and the charge of the first capacitor C1 A DC / DC converter 5 that controls the voltage to be a direct current voltage supplied to the switching load 20, and the second boost converter 3 is configured to turn off the switching load 20 in synchronization with the switching operation of the switching load 20. Charged charge of the second capacitor C2 during the period is input to the DC / DC converter 5 during the operation on period of the switching load 20 And it includes a conductive circuit.

  It is principal part explanatory drawing of Example 1 of this invention, and shows the case where a distribution line is made into a three-phase three-wire system, 1 is a power supply device, 2 is a rectifier circuit, 3 is a 2nd boost converter, 4 is a discharge circuit 5 is a DC / DC converter, 6 is a first boost converter, C1 and C2 are first and second capacitors, Q1 and Q2 are transistors, R is a resistor, and the first boost converter 6 and the second As shown in the lower frame, the boost converter 3 includes a choke coil L1, a diode D1, and a transistor Q1, and the control means (not shown) turns the transistor Q1 on and off. Is controlled.

  The three-phase 200V AC voltage is full-wave rectified by the rectifier circuit 2 and supplied to the first boost converter 6 and the second boost converter 3, and the first boost converter 6 supplies the desired output voltage to the first boost voltage. The first capacitor C1 is charged by being applied, the charging voltage of the first capacitor C1 is input to the DC / DC converter 5, and the switching operation in the DC / DC converter 5 determines the switching load 20 depending on the type. A desired output voltage is generated, and the output voltage is applied to the switching load 20. In addition, the second boost converter 3 performs a switching operation during the idle period of the switching load 20 to charge the second capacitor C2, and charges the second capacitor C2 to the transistor during the operation period of the switching load 20. Q2 is turned on and supplied to the DC / DC converter 5. Therefore, the first boost converter 6 and the DC / DC converter 5 continuously perform switching control to supply operating power to the switching load 20, but the second boost converter 3 is in the idle period of the switching load 20. In this case, switching control is performed to charge the second capacitor C2.

  FIG. 2 is an operation explanatory diagram of Embodiment 1 of the present invention, showing the three-phase full-wave rectified output voltage of the rectifier circuit 2 of the power supply device 1 as an input voltage, and showing the current on the three-phase AC voltage side as an input current. In addition, a pause period and an operation period of the switching load 20 are shown as loads. In the operation period of the switching load 20, the three-phase alternating current flows mainly due to the charging voltage of the first capacitor C 1 corresponding to the switching operation, and in the rest period of the switching load 20, Since the charging current of the second capacitor C2 by the second boost converter 3 flows, the three-phase alternating current flowing through the rectifier circuit 2 flows even in the idle period, and the three-phase alternating current is almost continuous. It will flow to. Therefore, the three-phase AC voltage hardly fluctuates, and flickering of lighting when the lighting device is connected in parallel with the power supply device 1 can be prevented.

  3 is an explanatory diagram of the first embodiment of the present invention. The same reference numerals as those in FIG. 1 denote the same parts, 7 is an ON / OFF control unit, 8 is a current detection unit, 9 is a reference voltage, and 10 is an error amplifier. , 11 is a PWM control unit, 12 is a drive circuit, 13 is a reference voltage, 14 is a comparator, 15 and 16 are resistors, and 17 is a current feedback circuit. In addition, the 1st boost converter 6 can be set as the structure similar to the 2nd boost converter 3, In that case, the structure controlled from the ON / OFF control part 7 is not included. A three-phase 200 V AC voltage from a commercial AC power supply is full-wave rectified by the rectifier circuit 2 and input to the first boost converter 6 and the second boost converter 3, and the first boost converter 6 performs the first operation. The capacitor C1 is charged and the second boost converter 3 charges the second capacitor C2. However, the first boost converter 6 continuously outputs a predetermined voltage by the switching operation to charge the first capacitor C1, but the second boost converter 3 does not operate the switching load 20. Then, the switching operation is performed to charge the second capacitor C2. The discharge circuit 4 inputs the charge of the second capacitor C2 to the DC / DC converter 5 through the transistor Q2 and the resistor 16 together with the charge of the first capacitor C1. For this purpose, an ON / OFF control signal indicating an operation period and a rest period of the switching load 20 is input to the ON / OFF control unit 7.

  The ON / OFF control unit 7 controls the operation of the second boost converter 3 and the discharge circuit 4 according to the on / off control signal. During the operation period in which the load current flows through the switching load 20, the ON / OFF control unit 7 The voltage 13 is controlled to a predetermined value, and compared with the emitter potential of the transistor Q2 by the comparator 14. When the emitter potential is lower than the reference voltage 13, the transistor Q2 is turned on, and the charge of the second capacitor C2 is changed to the transistor The signal is input to the DC / DC converter 5 via Q2 and the resistor 16. When the voltage of the reference voltage 13 is set to zero or a value close thereto, the comparison output from the comparator 14 is zero, the transistor Q2 is turned off, and the discharge from the second capacitor C2 to the DC / DC converter 5 side is not performed. Stop.

  The current feedback circuit 17 detects the current flowing from the first boost converter 6 through the DC / DC converter 5 to the switching load 20 by the current detection unit 8 and compares it with the reference voltage 9 by the error amplifier 10. The comparison error is input to the PWM control unit 11. The PWM control unit 11 controls the ON period of the transistor Q1 through the drive circuit 12, and controls the current flowing through the second capacitor C2 through the diode D1 to a predetermined value corresponding to the reference voltage 9. Therefore, during the rest period of the switching load 20, the second capacitor C <b> 2 is charged, so that a current flows continuously from the AC power supply to the power supply device 1. During the suspension period of the switching load 20, the operation stop of the drive circuit 12 is controlled by the ON / OFF control unit 7, and the charging operation of the second capacitor C2 is stopped.

  The first boost converter 6 and the second boost converter 3 are set to output voltages in consideration of the withstand voltage of the first capacitor C1 and the second capacitor C2, and the DC / DC converter 5 causes the switching load 20 to be set. By controlling the voltage so as to be necessary, the operating voltage is supplied to the various switching loads 20, the fluctuation of the current flowing to the AC power supply side can be suppressed, and the flicker generation of the lighting device can be suppressed. .

  FIG. 4 is an explanatory diagram of a main part of the second embodiment of the present invention, and the same reference numerals as those in FIG. 1 denote the same parts. In the second embodiment, an output voltage for charging the first capacitor C 1 is input from the first boost converter 6 to the second boost converter 3, and the second boost converter 3 outputs the second voltage during the idle period of the switching load 20. A case where the second capacitor C2 is charged is shown. In the second embodiment, the configuration of the second boost converter 3 that performs the switching control only during the idle period of the switching load 20 can be simplified as compared with the configuration of the first embodiment.

  FIG. 5 is an explanatory diagram of Embodiment 2 of the present invention, and the same reference numerals as those in FIG. 3 denote the same parts. The first boost converter 6 has substantially the same configuration as the second boost converter 3, but does not include a configuration controlled by the ON / OFF control unit 7. Further, an on / off control signal of the switching load 20 is input to the ON / OFF control unit 7, and the operation of the drive circuit 12 is started from the ON / OFF control unit 7 during the rest period of the switching load 20, The charging of the capacitor C2 is started, and the discharging operation of the discharging circuit 4 is stopped. Thereby, even if the charging current of the first capacitor C1 decreases from the first boost converter 6, the charging current for the second capacitor C2 flows. Therefore, there is almost no current fluctuation on the AC power supply side, and it is possible to avoid the flickering of lighting when the lighting device is connected to the distribution line in parallel with the power supply device 1.

  Moreover, although the rectifier circuit 2 in the above-mentioned Example 1 and Example 2 shows the case of the structure which carries out the full wave rectification of the three-phase 200V alternating voltage, it can also be set as the structure which rectifies the alternating voltage of single phase 100V. It is also possible to rectify a single-phase 200V AC voltage. In addition, the switching load 20 may be configured to include not only a printer that performs fixing processing by discharge light emission but also an operation period and a pause period.

  6 is an explanatory diagram of Embodiment 3 of the present invention. The same reference numerals as those in FIG. 5 denote the same parts, 21 is a boost converter, 22 is a comparator, 23 is a reference voltage output unit, and R1 and R2 are for voltage division. Of resistance. The boost converter 21 corresponds to the first boost converter 6 described above, charges the first capacitor C1, and supplies the terminal voltage of the first capacitor C1 to the switching load 20 via the DC / DC converter 5. To do. The on / off control signal of the switching load 20 is input to the ON / OFF control unit 7, and the reference voltage output unit 23 is controlled from the ON / OFF control unit 7 to change the reference voltage input to the comparator 22. . The reference voltage is gradually increased during the operation off period of the switching load 20 and gradually decreased during the operation on period.

  A voltage obtained by dividing the terminal voltage of the first capacitor C1 by the resistors R1 and R2 is detected by the output voltage of the boost converter 21 (terminal voltage of the capacitor C1) and input to the comparator 22. The comparison output signal of the comparator 22 is input to the error amplifier 10, the current supplied to the switching load 20 via the DC / DC converter 5 is detected by the current detection unit 8, and the detected current value is input to the error amplifier 10. To do. The output signal of the error amplifier 10 is input to the PWM controller 11 to control the ON period of the switching transistor Q1 by the drive circuit 12.

  The current supplied through the boost converter 21 and the DC / DC converter 5 during the operation off period of the switching load 20 decreases. However, by raising the output reference voltage of the reference voltage output unit 23, the switching transistor Q1. Can be lengthened, whereby the current flowing from the AC power supply to the capacitor C1 via the rectifier circuit 2 increases, and the change in the current supplied from the AC power supply can be suppressed. Accordingly, it is possible to prevent flickering of lighting when a lighting fixture is connected in parallel with the power supply device 1. Further, the AC voltage fluctuation can be suppressed with a simple configuration as compared with the configuration of the embodiment shown in FIG. 3 or FIG.

  FIG. 7 is an operation explanatory diagram, where (a) shows the output reference voltage of the reference voltage output unit 23, (b) shows the current flowing through the switching load 20, and (c) shows the output voltage of the boost converter 21. That is, during the pause period of the switching load 20, the current becomes zero or a value close thereto as shown in (b), and continuously flows during the operation period. However, as shown in (c), the output voltage of the boost converter 21 rises during the idle period, so that the charging current to the capacitor C1 increases, and the output voltage gradually decreases during the operation period. A predetermined voltage maintained by the DC converter 5 can be supplied to the switching load 20.

It is principal part explanatory drawing of Example 1 of this invention. It is operation | movement explanatory drawing of Example 1 of this invention. It is explanatory drawing of Example 1 of this invention. It is principal part explanatory drawing of Example 2 of this invention. It is explanatory drawing of Example 2 of this invention. It is explanatory drawing of Example 3 of this invention. It is operation | movement explanatory drawing of Example 3 of this invention. It is explanatory drawing of a prior art example. It is operation | movement explanatory drawing of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power supply device 2 Rectifier circuit 3 2nd boost converter 4 Discharge circuit 5 DC / DC converter 6 1st boost converter 7 ON / OFF control part 8 Current detection part 9 Reference voltage 10 Error amplifier 11 PWM control part 12 Drive circuit 13 Reference voltage 14 Comparator 15, 16 Resistor 17 Current feedback circuit 20 Switching load 21 Boost converter 22 Comparator 23 Reference voltage output unit C1, C2 First and second capacitors Q1, Q2 Transistor D1, Diode L1 Choke coil

Claims (4)

In a power supply that supplies power to a switching load,
A rectifier circuit for rectifying an alternating voltage;
A first boost converter that boosts the rectified output voltage of the rectifier circuit and charges the first capacitor;
A second boost converter for boosting a rectified output voltage of the rectifier circuit and charging a second capacitor;
A DC / DC converter that controls the charging voltage of the first capacitor to be a DC voltage supplied to the switching load;
The second boost converter synchronizes with the switching operation of the switching load, and charges the second capacitor during the operation off period of the switching load, and the DC / DC during the operation on period of the switching load. A power supply apparatus comprising a discharge circuit for input to a DC converter.   The second boost converter controls a charging current of the second capacitor based on information about operation off of the switching load, and stops charging of the second capacitor based on information about operation on of the switching load. And discharging to perform a control to stop the discharge operation of the capacitor by applying the charge of the second capacitor to the DC / DC converter according to the information of the operation on of the switching load being applied to the DC / DC converter. The power supply device according to claim 1, further comprising a circuit.   The first boost converter for inputting the rectified output voltage of the rectifier circuit, the second boost converter for inputting the output voltage of the first boost converter, the first capacitor, and the second capacitor. The power supply apparatus according to claim 1, further comprising: a DC / DC converter that inputs charging charges. In a power supply that supplies power to a switching load,
A rectifier circuit for rectifying an alternating voltage;
A boost converter that boosts the rectified output voltage of the rectifier circuit by on / off control of a switching transistor to charge a capacitor;
A DC / DC converter that controls the charging voltage of the capacitor to be a DC voltage supplied to the switching load;
The boost converter includes a reference voltage output unit that sequentially decreases an output reference voltage according to information on operation on of the switching load and sequentially increases an output reference voltage according to information about operation off, and an output reference of the reference voltage output unit A comparator for comparing a voltage with a detected voltage obtained by detecting a terminal voltage of the capacitor, a comparison output signal of the comparator, and a detected current value for detecting a current supplied to the switching load via the DC / DC converter; And a drive circuit that controls the on period of the switching transistor in accordance with an output signal of the error amplifier.

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