JP2008104250A - Dc power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the generation of the noise of a reactor, switching noise and a switching loss, in a DC power supply device which is achieved in the reduction of a harmonic current and improved in power factor. <P>SOLUTION: This DC power supply device comprises: the reactor 2 which is connected to an AC power supply 1; a bridge rectifying circuit 3; a smoothing capacitor 7; a bidirectional switch 4 which makes a short-circuit current flow to the reactor 2; a capacitor 5 and an auxiliary switch 6 which are connected in series; a zero-cross detection means 9 which detects an AC voltage zero point; and a switch drive control means 10. The generation of noise is suppressed by preventing an abrupt change of a voltage of the reactor 2 by turning on the auxiliary switch 6 during the bidirectional switch 4 is turned on and off, and the reduction of the noise and the loss can be achieved by conducting the zero-current switching and the zero-voltage switching of the bidirectional switch 4 and the auxiliary switch 6. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a DC power supply device that converts AC to DC and reduces harmonic current flowing in the AC power supply to improve the power factor.

  Conventionally, in a DC power supply device of up to about several kW output, one or two switches are used, and the switch is turned on / off once or several times in a half cycle of the AC power supply, thereby generating a harmonic current of the AC power supply. A method of reducing AC and improving the power factor and converting AC to a target DC voltage has been adopted.

  For example, a conventional DC power supply device includes a combination of a bridge rectifier circuit, a reactor, a switch, and a backflow prevention diode (see, for example, Patent Document 1).

  A conventional DC power supply device will be described below with reference to FIGS. 10 and 11 with reference to the drawings. FIG. 10 shows a circuit block diagram of a conventional DC power supply device described as a representative diagram of Patent Document 1. In FIG. The AC power source 1 is a single-phase commercial AC power source, and the bridge rectifier circuit 3 is composed of four diodes. The reactor 2 is connected to the positive output of the bridge rectifier circuit 3 and the switch 18 and the anode terminal of the backflow prevention diode 19, and the smoothing capacitor 7 is connected to the cathode terminal of the backflow prevention diode 19 to smooth the DC voltage, and the load 8 Supply a DC voltage with small pulsation. The switch control circuit 20 includes an on timing generation circuit 21 of the switch 18, an off timing generation circuit 22, and a switch drive circuit 23.

  Next, the operation of the DC power supply device configured as described above will be described. The on-timing generation circuit 21 synchronizes with the power supply voltage of the AC power supply 1 and sends a signal for driving the switch 18 from the zero voltage point of the AC power supply 1 through the switch drive circuit 23 with a predetermined drive delay time. And send it out. When the switch 18 is closed, a short-circuit current starts to flow in the AC power source 1 via the reactor 2 and the bridge rectifier circuit 3 and gradually increases.

  Next, when a signal for stopping the switch 18 is sent from the off-timing generation circuit 22 through the switch drive circuit 23 in synchronization with the power supply voltage, the switch 18 is opened and the short-circuit current that has been flowing through the reactor 2 until then. Begins to decrease as the charging current of the smoothing capacitor 7 through the backflow prevention diode 19. Thereafter, when the power supply voltage of the AC power supply 1 becomes near the peak voltage, a charging current flows from the AC power supply 1 to the smoothing capacitor 7 through the bridge rectifier circuit 3, the reactor 2, and the backflow prevention diode 19. FIG. 11 shows the power supply voltage Vi of the AC power supply 1 at this time, and the low load input current I1 and the high load input current I2 of the AC power supply 1. As can be seen in the figure, the on-timing signal from the on-timing generation circuit 21 is controlled so as to be delayed when the load is low than when the load is high. And by controlling in this way, the flow angle of the input current from the AC power supply 1 is widened, and the harmonic current reduction and the power factor improvement are realized.

  However, this circuit configuration has a drawback that the efficiency is poor because the loss of the backflow prevention diode is large. Therefore, a circuit-type DC power supply device has been proposed in which the switch is a bidirectional switch, the reactor is short-circuited on the AC side of the bridge rectifier circuit, and the backflow prevention diode is omitted to achieve high efficiency (see, for example, Patent Document 2). .

A detailed explanation of the operation of this circuit configuration is omitted, but the energy stored in the reactor by turning on the bidirectional switch once or several times in a half cycle of the AC power supply frequency is stored in the smoothing capacitor when the bidirectional switch is turned off. By discharging to the side, the same effect as the conventional DC power supply device using the switch on the DC side is obtained. A basic circuit configuration is shown in FIG.
Japanese Patent Laid-Open No. 7-7946 Japanese Patent Laid-Open No. 10-337031 (FIG. 1)

  However, in the conventional DC power supply device, in order to maintain the continuity of the current flowing through the reactor when the DC side switch or the AC side bidirectional switch is turned off, a steep voltage fluctuation occurs in the reactor, Due to this, there was a problem that noise was generated from the reactor. In addition, in order to solve this problem, it is necessary to insert a resin material for noise reduction in the gap of the reactor and to shield the noise from the reactor, leading to an increase in cost.

  Further, even in the conventional DC power supply device for reducing the noise from the reactor, in Patent Document 2 described above, noise is reduced by driving the bidirectional switch again for a short time after the bidirectional switch is stopped. In this case, new problems such as noise generation and loss increase due to recovery current flowing through the bidirectional switch on / off and the backflow prevention diode or the bridge diode have occurred.

  Also, in the conventional DC power supply device, zero current switching is achieved when the DC side switch or AC side bidirectional switch is on, but when it is off, switching loss and switching noise are generated to cut off the reactor current. There was also a problem.

  To reduce this noise, a snubber circuit that absorbs surge voltage is added. Alternatively, a technique such as strengthening a noise filter provided on the AC input side has been taken, but switching loss and snubber circuit loss cannot be reduced, and there is a problem that costs are increased.

  Furthermore, in the conventional DC power supply device, when the DC side switch or the AC side bidirectional switch is turned off, the current change flowing through the reactor is steep, so that the harmonic reduction effect and the input power factor improvement effect are enhanced. Needed to increase the inductance of the reactor.

  In order to solve the above-described conventional problems, the DC power supply device of the present invention maintains the continuity of the reactor current by using the charging / discharging of the capacitor by turning on the auxiliary switch before the bidirectional switch is turned off. Thus, it is possible to moderate the voltage fluctuation of the reactor, reduce noise, and reduce switching loss and switching noise when the bidirectional switch is off.

  The direct-current power supply device of the present invention can reduce noise by easing the steep voltage fluctuation of the reactor caused by turning off the bidirectional switch, and can reduce the cost of resin material and noise shielding for noise prevention. In addition, by selecting a value within the range that varies from zero volts to DC output voltage by turning on and off the auxiliary switch, zero voltage switching is possible even when the bidirectional switch is turned off. In principle, noise can be prevented from being generated, and the snubber circuit and noise filter can be reduced or the burden can be reduced.

  In addition, if the capacitance of the capacitor is increased, the voltage fluctuation of the capacitor due to the on / off of the auxiliary switch will not fluctuate from zero volts to the DC output voltage, and zero current switching and zero voltage switching of the bidirectional switch and auxiliary switch cannot be realized. However, it is possible to increase the DC output voltage boosting capability by increasing the energy with which the capacitor is charged and discharged, and to increase the effect of suppressing harmonic current and improving input power factor, or suppressing harmonic current. It is possible to set the inductance of the reactor low while keeping the effect of improving the input power factor equivalent to the conventional one. The steep voltage fluctuation width of the reactor is smaller than that of the conventional DC power supply device, and therefore, a certain noise reduction effect can be provided.

  And when the capacitance of the capacitor is increased, the DC output voltage boosting capability is further increased and the harmonic current is increased while turning on and off the bidirectional switch and auxiliary switch multiple times in a half cycle to greatly improve the input power factor. Even in this case, since the steep voltage fluctuation range of the reactor is smaller than that of the conventional DC power supply device, a certain noise reduction effect can be provided.

  Furthermore, the energy stored in the capacitor regardless of the size of the capacitor can be released to the direct current side without being consumed as heat as in a general snubber circuit, which can contribute to higher efficiency.

  The first invention is connected between an AC power source, a bridge rectifier circuit formed by four diodes, a smoothing capacitor for smoothing the DC output of the bridge rectifier circuit, and the AC power source and the bridge rectifier circuit. A capacitor connected in series between the reactor, a bidirectional switch connected between the AC input terminals of the bridge rectifier circuit, and one of the AC input terminals and one of the DC output terminals of the bridge rectifier circuit And an auxiliary switch, a zero cross detecting means for detecting a zero point of the voltage of the AC power supply, and a switch driving control means for controlling on / off of the auxiliary switch and the auxiliary switch based on the output of the zero cross detecting means. Therefore, the input power factor can be improved and the harmonic current can be reduced.

  According to a second invention, in the first invention, the switch drive control means turns on and off the bidirectional switch and the auxiliary switch once every half cycle of the AC power supply to reduce the harmonic current and improve the input power factor. Since the auxiliary switch is turned on after the bidirectional switch is turned on and before it is turned off, switching noise and switching loss when the bidirectional switch is turned off can be reduced. By suppressing sudden fluctuations in voltage, it is possible to reduce costs such as reducing reactor noise and reducing the effects of these effects.

  According to a third aspect, in the first aspect, the switch drive control means turns on and off the bidirectional switch and the auxiliary switch a plurality of times in a half cycle of the AC power supply to reduce the harmonic current and improve the input power factor. And the auxiliary switch is turned on before the bidirectional switch is turned on after the bidirectional switch is turned on, and then the auxiliary switch is turned off until the bidirectional switch is turned on. The switching noise and switching loss when the power switch is turned off can be reduced, and by suppressing the rapid fluctuation of the reactor voltage, the cost of the reactor can be reduced and the cost can be reduced due to these effects.

  According to a fourth aspect of the present invention, there is provided DC voltage detecting means for detecting the voltage of the smoothing capacitor in any one of the first to third aspects, and the switch drive control means has a desired target for the DC voltage detected by the DC voltage detecting means. Since the ON time of the bidirectional switch is controlled so as to be equal to the DC voltage, a stable DC voltage can be supplied to the load.

  According to a fifth aspect of the present invention, in any one of the first to third aspects, a load amount determination unit for determining a load amount based on a DC output current or a DC output power is provided, and the switch drive control unit is detected by the load amount detection unit. Since the ON time of the bidirectional switch is controlled in accordance with the load amount, a stable DC voltage can be supplied to the load.

  According to a sixth aspect of the present invention, in any one of the first to third aspects, a compressor drive device is provided on the DC output side as a load, and the switch drive control means is a bidirectional switch according to the rotational speed command of the compressor drive device. By controlling the on-time, it is possible to supply a stable DC voltage to the load.

  In a seventh aspect based on any one of the first to fifth aspects, the switch drive control means sets the delay time from the voltage zero point detected by the zero cross detection means to the bidirectional switch drive. Since the control is performed based on the on-time, the DC voltage or the load amount, or the rotational speed command of the compressor driving device, it is possible to further reduce the harmonic current and improve the input power factor.

  In an eighth aspect based on the sixth aspect, the switch drive control means determines the delay time from the voltage zero point detected by the zero cross detection means to the bidirectional switch drive, the on-time of the bidirectional switch, the DC voltage or Since the control is performed according to the load amount or the rotation speed command of the compressor drive device, it is possible to further reduce the harmonic current and improve the input power factor.

(Embodiment 1)
FIG. 1 is a block diagram of a DC power supply device according to a first embodiment of the present invention. In FIG. 1, an AC power source 1 is rectified by a bridge rectifier circuit 3, smoothed to DC by a smoothing capacitor 7, and a DC voltage is supplied to a load 8 in the same manner as in the prior art. The reactor 2 is connected between the AC power source 1 and the AC input terminal of the bridge rectifier circuit 3, and the bidirectional switch 4 is connected between the two AC input terminals of the bridge rectifier circuit 3. One of the capacitors 5 is connected to the AC input terminal of the bridge rectifier circuit 6 and the other is connected to the auxiliary switch 6. The auxiliary switch 6 has the other terminal connected to the negative output terminal of the bridge rectifier circuit 3. The zero cross detection means 9 detects the zero voltage point of the AC power source 1, and the switch drive control means 10 controls the bidirectional switch 4 and the auxiliary switch 6.

  In the above configuration, the operation and action will be described below with reference to FIGS. 2 to 6. The basic operation of turning on and off the bidirectional switch to suppress the harmonic current and improve the input power factor is described below. Since it is the same as that of the prior art, a detailed description of these effects will be omitted.

  FIG. 2 is a waveform diagram showing the driving timing of the bidirectional switch 4 and the auxiliary switch 6 with respect to the input voltage and the input current waveform during one cycle of the AC power source 1. FIG. 3 is a diagram showing a circuit state at a voltage zero timing at which the voltage of the AC power supply 1 switches from negative to positive, and shows an initial state for the following description. FIG. 4 shows the on / off state of the bidirectional switch 4 and the auxiliary switch 6 in the positive half cycle of the AC power supply 1, the current flowing in the circuit, and the voltage change of the capacitor 5. FIG. The figure which showed the circuit state in the voltage zero timing in which the voltage of the power supply 1 switches from positive to negative, and FIG. 6 are the states of ON / OFF of the bidirectional switch 4 and the auxiliary switch 6 in the negative half cycle of the alternating voltage 1. 2 shows the flow of current flowing through the capacitor 5 and the voltage change of the capacitor 5.

Next, in describing the operation, the initial state of FIG. 3 will be clarified. In this initial state, the initial charging value of the capacitor 5 is set to zero volts with reference to the voltage zero cross point at which the voltage Vi of the AC power supply 1 enters the positive half cycle. The voltage of the smoothing capacitor 7 is maintained at a predetermined DC voltage Vdc (hereinafter simply referred to as Vdc). At this time, no current flows in the circuits other than the load 8, and the load current is not considered in the following description. Further, the bidirectional switch 4 and the auxiliary switch 6 are both turned off. Since this time is the voltage zero point of the AC power supply 1, it is also the time when the zero cross timing signal is sent to the switch drive control means 10 by the zero cross detection means 9.

  Then, the switch drive control means 10 turns on the bidirectional switch 4 after a predetermined delay time has elapsed since receiving the zero cross timing signal. Naturally, since no current flows in the circuit until this time, the bidirectional switch 4 performs zero current switching. Thereafter, the AC power source 1 is short-circuited by the reactor 2 via the bidirectional switch 4 and the current flowing through the reactor 2 continues to increase. The circuit state and the flow of reactor current IL (hereinafter simply referred to as IL) at this time are shown in FIG.

  Thereafter, the auxiliary switch 6 is turned on immediately before the bidirectional switch 4 is turned off after a predetermined time has elapsed, and then the bidirectional switch 4 is turned off. As a result, the current IL that has been flowing through the bidirectional switch 4 until now flows continuously as the charging current of the capacitor 5, and the initial value of the charging voltage of the capacitor 5 is zero volts as described above. Zero volt switching of the switch 4 is realized. Further, zero current switching is realized on the auxiliary switch 6 side. FIG. 4B shows a circuit state and a current flow when the current IL is commutated from the bidirectional switch 4 to the capacitor 5 and the auxiliary switch 6.

  Eventually, the charging voltage of the capacitor 5 exceeded the DC output voltage Vdc (hereinafter simply referred to as Vdc), and accurately exceeded the voltage obtained by adding the on-voltage of the internal diode of the bridge rectifier circuit 3 to Vdc. At this time, the current IL commutates in the bridge rectifier circuit 3. Next, zero current switching of the auxiliary switch 6 can be realized by turning off the auxiliary switch 6. On the other hand, the time until the voltage of the capacitor 5 rises and exceeds Vdc can be estimated if the current IL at the start of charging is known, and the current IL is constant when the voltage of the AC power supply 1 is constant. Then, it is possible to estimate in advance from the drive delay time and the ON time of the bidirectional switch 4. Therefore, the auxiliary switch 6 may be turned off after a sufficient time has elapsed for the voltage of the capacitor 5 to exceed Vdc in consideration of fluctuations in the voltage of the AC power supply 1 and variations in drive delay time. The circuit state and current flow at this time are shown in FIG.

  After the auxiliary switch 6 is turned off, the current IL flows due to the release of energy stored in the reactor 2 and the charging from the AC power supply 1 as in the case of the conventional DC power supply device, and eventually becomes zero.

  Subsequently, the negative half-cycle operation of the AC power supply 1 will be described. FIG. 5 is a diagram showing an initial state of the negative half cycle in which the current IL of the reactor 2 at the end of the positive half cycle is zero, and the voltage of the capacitor 5 is higher than the initial state of the positive half cycle. The difference is that Vdc is charged. The same applies to the point that the zero-cross timing signal is sent to the switch drive control means 10 by the zero-cross detection means 9 at this timing.

  Then, the switch drive control means 10 turns on the bidirectional switch 4 after a predetermined delay time has elapsed since receiving the zero cross timing signal. Naturally, at this time, zero current switching is performed as described above. Thereafter, the AC power source 1 is short-circuited by the reactor 2 via the bidirectional switch 4 and the current IL flowing through the reactor 2 continues to increase. The circuit state and the current flow at this time are shown in FIG.

Thereafter, the auxiliary switch 6 is turned on immediately before the bidirectional switch 4 is turned off after a predetermined time has elapsed, and then the bidirectional switch 4 is turned off. As a result, the current IL that has been flowing through the bidirectional switch 4 until now flows continuously as the discharge current of the capacitor 5, and the initial value of the charging voltage of the capacitor 5 is Vdc as described above. When the switch 4 is turned off, the voltage across the bidirectional switch 4 becomes the same potential, and zero volt switching is realized. Further, the auxiliary switch 6 realizes zero current switching. FIG. 6B shows the circuit state and current flow when the current IL commutates to the capacitor 5 and the bidirectional switch 4 is turned off.

  The voltage across the reactor 2 rises according to the voltage fluctuation caused by the discharge of the capacitor 5, and when the capacitor 5 is completely discharged, the current IL is commutated to the bridge rectifier circuit 3, and the current is passed through the capacitor 5 and the auxiliary switch 6. It stops flowing. Thereafter, when the auxiliary switch 6 is turned off, the auxiliary switch 6 performs zero current switching. The time until the auxiliary switch 6 is turned off may be set after a sufficient time has elapsed for the voltage of the capacitor 5 to complete the discharge in consideration of voltage fluctuations and variations in drive delay time. The circuit state and current flow at this time are shown in FIG.

  After the auxiliary switch 6 is turned off, the current IL flows through the discharge of energy stored in the reactor 2 and the charging from the AC power supply 1 as in the conventional DC power supply device, and eventually becomes zero. And it will return to the initial state shown in FIG.

  Although one period of the commercial frequency has been described above, when FIG. 2 showing these waveforms and timings as a whole is viewed, the current waveform and the like seem to hardly change depending on the operation of the auxiliary switch 12. However, in actuality, the time until the current IL of the reactor 2 is commutated to the bridge rectifier circuit 3 is that the current IL when the auxiliary switch 6 is turned on is 20 A, the capacity of the capacitor 5 is 2 uF, and Vdc is 280 V. If this is done, it can be increased to nearly 30 us, which is sufficiently larger than the several hundred ns, which is the commutation time when only the bidirectional switch 4 is turned off. Therefore, significant noise reduction can be realized.

  In FIG. 1, the auxiliary switch 6 is connected to the negative electrode of the bridge rectifier circuit 3. However, the same effect can be obtained by changing the auxiliary switch 6 to be connected to the positive electrode. The same effect can be obtained regardless of which terminal is connected. Of course, the connection order of the capacitor 5 and the auxiliary switch 6 may be switched. However, if the auxiliary switch 6 is connected to the negative electrode of the bridge rectifier circuit 3 as shown in FIG. 1, the circuit for driving the auxiliary switch 6 can be configured non-insulated from the control circuit and can be simplified. is there.

  Further, in the present embodiment, the description has been made on the assumption that a switch capable of flowing a current in both directions is combined with a self-extinguishing semiconductor switch or the like as an auxiliary switch, but a triac may be used as the auxiliary switch 6. Is not self-extinguishing, but can be used because it shifts to the off state when the current becomes zero, and it is only necessary to give a short drive pulse while paying attention only to the drive timing for controlling the auxiliary switch 6. There are advantages that the relationship between the driving time of the auxiliary switch 6 and the capacitance of the capacitor 5 does not have to be strictly considered, and that the driving circuit can be simplified.

  Further, the delay time from the zero cross point until the bidirectional switch 4 is driven may be always constant or may not be provided, but may be changed according to the ON time of the bidirectional switch 4. This is because when the on-time of the bidirectional switch 4 is short, the drive delay time is long, and conversely, when the on-time is long, shortening the delay time is effective in reducing the harmonic current and improving the input power factor. .

  It is clear that when the delay time is shortened when the on-time of the bidirectional switch 4 is short, the IL continuity cannot be maintained, and as a result, the harmonic current increases and the input power factor also deteriorates. It can be explained that it is effective because it can be assumed easily.

  On the other hand, in this embodiment, it has been explained that noise reduction and switching loss and switching noise can be reduced on the assumption that the charge / discharge voltage of the capacitor 5 changes from zero volts to Vdc. It will be described that even if charging and discharging is performed, even if the voltage does not reach zero volt or Vdc, other effects can be obtained while reducing noise and switching loss and switching noise.

  In this case, when the bidirectional switch 4 is turned off, the voltage of the reactor 2 suddenly changes to the instantaneous voltage value of the capacitor 5 at that time, but the voltage fluctuation range can be suppressed to be smaller than when the capacitor 5 is not provided. it can. Further, since the charge stored in the capacitor 5 can be increased, the energy that can be released to the DC output side in the negative half cycle is increased, and there is an advantage that it is possible to contribute to the improvement of the DC voltage boosting capability. Further, when the resonance frequency of the reactor 2 and the capacitor 5 is further lowered, the current change becomes gentle, and the harmonic current can be reduced and the input power factor can be improved. Further, by utilizing the fact that the capacitor voltage does not reach Vdc when the auxiliary switch 6 is turned on and off once in a half cycle, switching loss can be reduced even if the bidirectional switch 4 and the auxiliary switch 6 are turned on and off a plurality of times. An effect of noise reduction can be obtained, and in this case, the input power factor can be greatly improved.

(Embodiment 2)
FIG. 7 is a block diagram of a DC power supply device according to the second embodiment of the present invention. In this example, the operation of the bidirectional switch 4 and the auxiliary switch 6 described in the first embodiment, noise reduction, switching noise, switching loss and harmonic current are reduced, and the input power factor is improved. The basic operations and effects of doing the same are the same.

  However, in FIG. 7, a DC voltage detecting means 11 is added as compared with the DC power supply device described in the first embodiment. The switch drive control means 10 lengthens the ON time of the bidirectional switch 4 when the DC voltage detected by the DC voltage detection means 11 is lower than the desired target DC voltage, and in the opposite case, the bidirectional switch 4. The DC voltage is stabilized by controlling the on-time of the short circuit. Therefore, in addition to the various effects described in the first embodiment, the DC power supply device in the present embodiment has an advantage that a stable DC voltage can be supplied to the load 8.

  Further, in the DC power supply device according to the present embodiment, the DC voltage detecting means 11 is used for stabilizing the DC output voltage. However, as shown in FIG. 8, the load amount for determining the load amount by detecting the DC current or the like. A detection unit 12 may be provided to control the on-time of the bidirectional switch 4. When the compressor drive device 14 is provided on the DC output side as a load as shown in FIG. 9, the switch drive control means 10 turns on the bidirectional switch 4 according to the rotational speed command of the compressor drive device 14. The DC voltage may be stabilized by controlling the time.

  Furthermore, in the DC power supply device according to the present embodiment, the switch drive control means 10 is configured to control the drive delay time for driving the bidirectional switch 4 based on the difference between the DC output voltage and the target voltage, thereby further increasing the harmonics. The wave current can also be reduced.

This shortens the drive delay time at light loads where the difference between the DC output voltage and the target voltage is small, and shortens the drive delay time at large loads, thereby making the current IL closer to a sine wave while maintaining continuity. This is because it becomes possible. This also means that the switch drive control means 10 operates in the same way because the load amount judgment means is different even when other detection means are used as shown in FIGS. To achieve the same effect.

  As described above, the DC power supply device according to the present invention can reduce noise and switching noise and switching loss in a DC power supply device capable of reducing harmonic current and improving power factor. Therefore, it can be applied to the input stage circuit of home appliances using a compressor such as a general-purpose inverter input stage circuit or an air conditioner or a refrigerator.

1 is a block diagram of a DC power supply device according to Embodiment 1 of the present invention. Voltage / Current Waveform Diagram of Each Part in Embodiment 1 of the Present Invention Initial state explanatory diagram in the positive half cycle of Embodiment 1 of the present invention Operation explanatory diagram in the positive half cycle of the first embodiment of the present invention Initial state explanatory diagram in the negative half cycle of Embodiment 1 of the present invention Operation explanatory diagram in the negative half cycle of Embodiment 1 of the present invention Block diagram when DC voltage detecting means is used in Embodiment 2 of the present invention Block diagram in the case of using load amount detection means in Embodiment 2 of the present invention Block diagram when a compressor driving device is used as a load in Embodiment 2 of the present invention Block diagram of a conventional DC power supply with a switch on the DC side Voltage / current waveform diagram of each part of conventional DC power supply Block diagram of a conventional DC power supply device with a switch on the AC side

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Reactor 3 Bridge rectifier circuit 4 Bidirectional switch 5 Capacitor 6 Auxiliary switch 7 Smoothing capacitor 8 Load 9 Zero cross detection means 10 Switch drive control means 11 DC voltage detection means 12 Load amount detection means 13 Compressor drive device 14 Compression Machine 15 Inverter circuit 16 Inverter control means

Claims (8)

An AC power source, a bridge rectifier circuit formed of four diodes, a smoothing capacitor for smoothing the DC output of the bridge rectifier circuit, a reactor connected between the AC power source and the bridge rectifier circuit, A bidirectional switch connected between the AC input terminals of the bridge rectifier circuit, a capacitor connected in series between one of the AC input terminals and one of the DC output terminals of the bridge rectifier circuit; An auxiliary switch, a zero-cross detection unit that detects a zero point of the voltage of the AC power supply, and a switch drive control unit that controls on / off of the bidirectional switch and the auxiliary switch based on an output of the zero-cross detection unit A direct current power supply device. The switch drive control means turns on and off the bidirectional switch and the auxiliary switch once in a half cycle of the AC power supply, turns on the auxiliary switch after the bidirectional switch is turned on, and then turns off the both. 2. The DC power supply device according to claim 1, wherein the auxiliary switch is turned off after a directional switch is turned off. The switch drive control means turns on and off the bidirectional switch and the auxiliary switch a plurality of times in a half cycle of the AC power supply, turns on the auxiliary switch between the time when the bidirectional switch is turned on and before turning off, 2. The DC power supply apparatus according to claim 1, wherein the auxiliary switch is turned off before the directional switch is turned on again. DC voltage detection means for detecting the voltage of the smoothing capacitor is provided, and the switch drive control means is configured to turn on the bidirectional switch so that the DC voltage detected by the DC voltage detection means becomes equal to a desired target DC voltage. The direct-current power supply device according to claim 1, wherein the direct-current power supply device is configured to control the power supply. Load amount detection means for determining a load amount based on a DC output current or DC output power of the bridge rectifier circuit is provided, and the switch drive control means is configured to switch the bidirectional switch according to the load amount detected by the load amount detection means. The direct-current power supply device according to any one of claims 1 to 3, wherein the on-time is controlled. Compressor drive means is provided as a load on the DC output side of the bridge rectifier circuit, and the switch drive control means is configured to control the on-time of the bidirectional switch in accordance with a rotational speed command of the compressor drive device. The direct-current power supply device according to any one of claims 1 to 3, wherein The switch drive control means controls the delay time from the voltage zero point detected by the zero-cross detection means to the drive of the bidirectional switch according to the ON time width of the bidirectional switch, the DC voltage or the load amount. The DC power supply device according to any one of claims 1 to 5, wherein the DC power supply device is configured. The switch drive control means determines the delay time from the voltage zero point detected by the zero cross detection means to the drive of the bidirectional switch, the on-time width of the bidirectional switch, the DC voltage or the load amount, or the compression 7. The DC power supply device according to claim 6, wherein the DC power supply device is configured to be controlled by a rotational speed command of the machine drive means.

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