JP4885603B2 - DC power supply - Google Patents

Description

  The present invention relates to a DC power supply device that generates a DC voltage from an AC voltage supplied from an AC power supply, and a motor driving device and an air conditioner using the DC power supply device.

  There is a device that converts electric power supplied from an AC power source into a DC voltage by rectification and smoothing, and further converts the voltage by an inverter circuit to supply power to a load.

  FIG. 7 is a circuit diagram of a DC power supply device disclosed in Patent Document 1. In FIG. 7, an AC voltage supplied from an AC power supply 30 is converted into DC by a power supply circuit including a rectifier diode bridge 32, voltage doubler rectifier capacitors 33 and 34, and a smoothing capacitor 35 via a reactor 31. The inverter circuit 36 receives the direct current and is connected to drive the variable capacity compressor 38 under the control of the control circuit 37.

In this circuit, when the voltage of the AC power supply exceeds the voltage of the voltage doubler rectifying capacitors 33 and 34, a current for charging the voltage doubler rectifying capacitors 33 and 34 starts to flow from the AC power supply. This current does not increase abruptly due to the inductivity of the reactor 31, and is doubled by the inductivity of the reactor 31 even after the voltage of the AC power supply 30 becomes lower than the voltage of the voltage doubler rectifying capacitors 33 and 34. The current flowing through the voltage rectifying capacitor does not suddenly become zero. Then, the current is converted into a substantially direct current state by the smoothing capacitor 35 and input to the inverter circuit 36, where it is shaped into an appropriate waveform by the switching element and applied to the variable capacity compressor.
JP 63-89051 A

  However, in such a configuration, even when the voltage of the AC power supply 30 exceeds the voltage of the voltage doubler rectifier capacitors 33 and 34, current does not flow rapidly and the voltage doubler rectifier capacitors 33 and 34 are not charged rapidly. Therefore, the substantially DC voltage of the smoothing capacitor 35 located on the downstream side does not rise rapidly.

  As a result, the voltage input to the inverter circuit 36 has a waveform having a ripple synchronized with the voltage cycle of the AC power supply 30. Therefore, the air conditioner that drives the variable capacity compressor motor using this DC power supply device. In this case, the torque generated in the compressor motor has the same ripple.

  Further, in such a configuration, the current supplied from the AC power supply 30 flows much near the peak of the AC power supply voltage, and does not flow near zero voltage, so the power factor is low and the amount of harmonics generated is large. There was a problem of becoming.

  In view of the above problems, the present invention suppresses a voltage ripple of a substantially DC voltage that is generated, and can improve a power factor, and a motor drive device and air using the DC power supply device The purpose is to provide a harmony machine.

  In order to achieve the above object, according to the present invention, a rectifying unit that rectifies an AC voltage from an AC power source to generate a DC voltage, a smoothing unit that smoothes the rectified DC voltage, an AC power source, and the rectifying unit, And a plurality of reactors connected in series, variable means for changing the capacity of the reactor, and control means for controlling the variable means.

  According to the above configuration, the reactor capacity can be reduced by varying the capacity of the reactor, whereby the DC voltage can be charged in the smoothing means more rapidly than in the prior art. For this reason, the drop in the substantially DC voltage in the smoothing means can be minimized, so that the voltage ripple can be reduced.

  Further, the rectifying means comprises charge storage means, and the control means operates the variable means in accordance with the timing when the voltage of the AC power supply exceeds the voltage of the charge storage means during a half cycle of the AC voltage. To do.

  According to the above configuration, the control means can operate the variable means when the voltage of the AC power supply exceeds the voltage of the charge storage means. By operating the variable means at this timing, it is possible to adjust the reactor capacity to be small, so that the smoothing means can be charged rapidly, and the substantially DC voltage that is the output of the DC power supply device can be obtained. Degradation is minimized. Therefore, the voltage ripple can be reduced.

  The control means can operate the variable means when the current supplied from the AC power supply becomes large. The capacity of the reactor can be rapidly increased by the operation of the appropriate variable means. As a result, an increase in current flowing in the DC power supply device can be suppressed, so that the waveform can be adjusted, and the overall power factor is improved.

  Further, the control means performs the operation of the variable means a plurality of times while the voltage of the AC power supply exceeds the voltage of the charge storage means during a half cycle of the AC voltage. By performing the operation of the variable means a plurality of times, the peak value of the current flowing into the smoothing means can be suppressed. Furthermore, the degree of freedom for adjusting the operation period of the variable means can be improved in accordance with the purpose for which power factor, average voltage amount, etc. are emphasized.

  In addition, a DC current detecting means for detecting the smoothed DC current or a DC voltage detecting means for detecting the smoothed DC voltage is provided, and the control means operates the variable means according to the detection result. And

  According to the above configuration, the DC power supply device can adjust the operation period of the variable means so that an optimum current flows depending on each energization state. Therefore, the voltage ripple can be reduced without depending on the load of the DC power supply device, and a high power factor can be maintained.

  Further, the variable means includes a short circuit that short-circuits at least one of a plurality of reactors connected in series, and a switching circuit that opens and closes the short-circuit.

  According to the above configuration, the variable means turns on the switching circuit when the alternating voltage supplied from the alternating current power source exceeds the voltage of the charge storage means, so that most of the current flowing through the reactor passes through the short circuit. It flows to the smoothing means. Therefore, since the amount of current flowing into the smoothing means increases relatively quickly, the voltage rise can also increase.

  In addition, a snubber circuit is provided in parallel with the short circuit. According to this configuration, when the short-circuit operation of the reactor is finished, the direct-current power supply device can alleviate sudden current fluctuation and generation of a surge voltage due to stray inductance. For this reason, noise due to this is reduced, and a malfunction in the peripheral portion can be avoided.

  Moreover, the current fluctuation at the end of the short-circuit operation is further moderated by making the capacitor capacity of the snubber circuit larger than usual. Thereby, the utilization efficiency of a power supply increases and a power factor can be improved.

  Further, the motor drive device includes the DC power supply device and inverter means for converting the smoothed DC voltage into variable frequency alternating current, the control means according to the output from the inverter means to the motor, The variable means is operated.

  According to the above configuration, the motor drive device is more responsive to control than the case where the phase section is controlled in accordance with a change in DC current or a change in DC voltage as a result of a change in motor output. Thereby, the period when voltage ripple increases and the period when power factor falls can be shortened.

  As described above, according to the present invention, since the capacity of the reactor can be adjusted to be reduced by the variable means, the charge accumulating means can be charged more rapidly than in the prior art. A drop in the DC voltage can be minimized and the amount of voltage ripple can be reduced.

  Further, the capacity of the reactor can be appropriately increased rapidly by the variable means when the current supplied from the AC power supply becomes large. Thereby, since an increase in current can be suppressed, the waveform is adjusted, and the overall power factor is also improved.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. The circuit shown in FIG. 1 is a motor drive device that receives an AC voltage from an AC power source 1 and drives a DC brushless motor 8, and a DC power source device A that converts an AC voltage from the AC power source 1 into a DC voltage; And an inverter circuit 7 connected to the output side of the DC power supply device A.

  The DC power supply device A includes reactors 2A to 2C that store and discharge according to a change in current supplied from the AC power supply 1, a rectifier diode bridge 3 that includes a plurality of diodes 3A to 3D, and a voltage doubler rectifier capacitor. 4A, 4B, a smoothing capacitor 5 for smoothing the rectified DC voltage, a DC voltage detection unit 6 composed of resistors 6A, 6B, a current detection unit 9 composed of shunt resistors, and controls them And a control calculation unit 11.

  The voltage doubler capacitors 4A and 4B serve as charge storage means, and the charge storage means and the rectifier diode bridge 3 constitute rectification means. Further, the smoothing capacitor 5 is a smoothing unit, the DC voltage detection unit 6 is a DC voltage detection unit, the current detection unit 9 is a current detection unit, and the control calculation unit 11 is a control unit.

  Three reactors 2 </ b> A to 2 </ b> C are provided between the AC power source 1 and the rectifying diode bridge 3, and they are connected in series. Further, one end of the reactor 2 </ b> A is connected to the AC power source 1, and one end of the reactor 2 </ b> C is connected to the rectifying diode bridge 3.

  The rectifying diode bridge 3 includes four diodes 3A to 3D. The output side of the rectifying diode bridge 3 is connected to voltage doubler rectifying capacitors 4A and 4B.

  The voltage doubler rectifying capacitors 4A and 4B are two capacitors connected in parallel to the output side of the rectifying diode bridge 3, and the smoothing capacitor 5 is connected to the output side thereof.

  The smoothing capacitor 5 removes voltage ripples included in the DC voltage output from the rectifying diode bridge 3. Therefore, by arranging the smoothing capacitor 5 between the voltage doubler rectifying capacitors 4A and 4B and the inverter circuit 7, a constant voltage can be obtained.

  In the DC voltage detection unit 6, a resistor 6 </ b> A and a resistor 6 </ b> B are connected in series on the output side of the smoothing capacitor 5. Further, the DC voltage detection unit 6 is connected to a connection point between the resistor 6A and the resistor 6B and the control calculation unit 11. With this configuration, the DC voltage detection unit 6 can detect the DC voltage output from the smoothing capacitor 5. Specifically, the control calculation unit 11 divides the voltage by the DC voltage detection unit 6 in a voltage range in which A / D conversion is possible, and the divided voltage is input to the control calculation unit 11 and detected.

  The current detection unit 9 is a shunt resistor connected between the DC voltage detection unit 6 and the inverter circuit 7. In addition, the current detection unit 9 is connected to the control calculation unit 11 on the input side and the output side. With this configuration, the current detection unit 9 can detect the direct current output from the smoothing capacitor 5. Specifically, the voltage value of the shunt resistor of the current detection unit 9 is detected by being input to the control calculation unit 11.

  The control calculation unit 11 is composed of a general microcomputer having a RAM, a ROM, and a CPU inside. The control calculation unit 11 controls the switching circuit C and the inverter circuit 7 based on inputs from the DC voltage detection unit 6 and the current detection unit 9.

  The inverter circuit 7 includes a plurality of circuits in which IGBTs (Insulated Gate Bi-polar Transistors) 7A to 7F and free wheel diodes 7G to 7L are paired, and each is connected in parallel. The output side of the inverter circuit 7 is connected to the DC brushless motor 8.

  Next, the operation of the motor driving device in the above circuit configuration will be described.

  The AC voltage supplied from the AC power source 1 is input to the rectifying diode bridges 3A to 3D via the reactors 2A to 2C. The rectifying diode bridges 3 </ b> A to 3 </ b> D rectify the input AC voltage and output it to the voltage doubler rectifying capacitors 4 </ b> A and 4 </ b> B and the smoothing capacitor 5. The voltage doubler rectifying capacitors 4A and 4B are charged every half cycle by the input voltage. The smoothing capacitor 5 smoothes the input voltage and outputs it to the inverter circuit 7. At this time, since the smoothing capacitor 5 is connected in parallel with the voltage doubler rectifier capacitors 4A and 4B, it outputs a DC voltage equal to the sum of the two voltage doubler rectifier capacitors 4A and 4B.

  The inverter circuit 7 outputs a current to each phase of the DC brushless motor 8 based on the PWM control signal input from the control calculation unit 11. The control calculation unit 11 detects the rotor position of the DC brushless motor 8 by a magnet induced voltage detection circuit (not shown), and performs PWM control on the IGBTs 7A to 7F so that the current of each phase of the motor flows for each predetermined electrical angle. Output a signal.

  The DC brushless motor 8 is driven by the current output from the inverter circuit 7. At this time, the current consumed by the DC brushless motor 8 is supplied from the smoothing capacitor 5. Therefore, the voltage of the smoothing capacitor 5 gradually decreases, and the voltages of the voltage doubler rectifying capacitors 4A and 4B also decrease. The smoothing capacitor 5 receives current from the AC power source 1 and the voltage is recovered.

  Specifically, when the current flowing in the direction of the arrow 12 in FIG. 1 is defined as the positive half cycle of the AC power source 1, the voltage of the voltage doubler rectifier capacitors 4A and 4B is changed to the AC power source 1 in the positive counter cycle. Current is supplied from the AC power supply 1 to the smoothing capacitor 5. Thereby, the voltage of the smoothing capacitor 5 is recovered. Note that the current flowing through the smoothing capacitor 5 does not increase rapidly due to the inductive components of the reactors 2A to 2C. Therefore, the voltage of the smoothing capacitor 5 does not rise rapidly.

  However, since the substantially DC voltage of the smoothing capacitor 5 does not rise rapidly, the voltage input to the inverter circuit 7 has a waveform having a voltage ripple synchronized with the voltage cycle of the AC power supply 1. Therefore, there is a problem that the torque generated by the DC brushless motor 8 has a similar voltage ripple. In such a configuration, a large amount of current supplied from the AC power supply 1 flows near the peak of the AC power supply voltage and does not flow near zero voltage. Therefore, there is a problem that the power factor is low and the generation amount of harmonics is also increased.

  Therefore, in the present embodiment, the DC power supply device A is provided with variable means for changing the capacity of the reactors 2A to 2C. By providing this variable means, it is possible to suppress the voltage ripple of the substantially DC voltage to be generated and improve the power factor.

  A variable means is comprised from the short circuit 10 which short-circuits the reactor 2B among the reactors 2A-2C connected in series, and the switching circuit C which opens and closes this short circuit 10. FIG.

  The short circuit 10 is composed of four diodes 10A to 10D, and its output is connected to the switching circuit C. Short circuit 10 is connected to a connection point between reactor 2A and reactor 2B and a connection point between reactor 2B and reactor 2C.

  The switching circuit C includes an IGBT 10E and a free wheel diode 10F, and the IGBT 10E is connected to the control calculation unit 11.

  According to the above configuration, when the AC voltage supplied from the AC power source 1 exceeds the voltage of the voltage doubler rectifying capacitor 4A, the variable means turns on the IGBT 10E of the switching circuit C and puts the short circuit 10 into a conductive state. To do. Then, most of the current flowing from reactor 2A to reactor 2C flows in the order of reactor 2A → diode 10A → IGBT 10E → diode 10D → reactor 2C. Therefore, since the amount of current flowing into the smoothing capacitor 5 relatively quickly increases, the voltage rise of the smoothing capacitor 5 also increases.

  FIG. 2 shows simulation waveforms of the power supply voltage, the DC link voltage (the voltages of the lines connecting the diodes 3A and 3B, the capacitor 4A, and the capacitor 5 to GND) and the power supply current during this operation.

  The constants of the components in the simulation waveform in FIG. 2 are as follows: AC power source 1 has an effective voltage of 100V-60 Hz, reactor 2A has 0.5 mH, reactor 2B has 4.0 mH, reactor 2C has 0.5 mH, voltage doubler rectifier capacitor It is assumed that 4A is 390 μF, the voltage doubler rectifying capacitor 4B is 390 μF, and the smoothing capacitor 5 is 820 μF. The inverter circuit 7 and the DC brushless motor 8 are a constant current source of DC 6.25A. Further, the ON period of the IGBT 10E is set to 10 to 90 degrees when the half cycle of the power supply voltage phase is set to 360 degrees. The average output at this time is about 1500 W.

  FIG. 3 shows simulation waveforms of the power supply voltage, the DC link voltage, and the power supply current during the operation of the conventional motor drive device. The circuit configuration for generating the simulation waveform of FIG. 3 is different from the circuit configuration of the present embodiment in that there is no variable means for changing the capacity of the reactor and only one 5.0 mH reactor is provided. Other components and component constants are the same. In addition, in order to make the average output of the conventional motor drive device 1500W, the inverter circuit and the motor are DC 6.10A constant current sources.

  As is clear from the comparison of the power supply current waveforms of FIG. 2 and FIG. 3, in FIG. 2, the current starts to flow rapidly because the inductive components of the reactors 2A to 2C are small, whereas in FIG. Since there are many inductive components, current begins to flow slowly. That is, the circuit configuration of FIG. 2 can charge the smoothing capacitor 5 more quickly, so that the drop of the DC link voltage is reduced and the voltage ripple is also reduced. This voltage ripple is 30V in FIG. 3, but 18V in FIG. That is, the circuit configuration of FIG. 2 can reduce the voltage ripple by 40% with respect to the circuit configuration of FIG. Further, the power factor (utilization efficiency) is 0.901 in FIG. 3 and 0.935 in FIG. That is, also in the power factor, the circuit configuration of FIG. 2 is improved compared to the circuit configuration of FIG.

  In addition, when the output is lower than the above case, for example, when the output is 750 W, the decrease in the DC link voltage is less than when the output is 1500 W, so the power supply voltage phase at which the power supply current starts to flow is delayed. .

  Therefore, when the output is 750 W, as in the case of the output 1500 W, the ON period of the IGBT 10E is set to 10 to 90 degrees of the power supply voltage phase. Then, the IGBT 10E is turned off soon after the power supply current starts to flow, and the effect of reducing the drop in the DC link voltage is diminished. Therefore, at this time, the ON period of the IGBT 10E is controlled to be 10 to 120 degrees of the power supply voltage phase, and the control is performed so as to lengthen the ON period.

  Such a period of the power supply voltage phase is a current detected by the current detection unit 9, a voltage detected by the DC voltage detection unit 6, or an output command to the DC brushless motor 8 controlled by the control calculation unit 11 itself. Judging by etc.

  For example, when the control calculation unit 11 detects and determines the current with the current detection unit 9, if the average value of the current detected from the current detection unit 9 is small, the current supply from the smoothing capacitor 5 to the DC brushless motor 8 is performed. It is judged that there are few. At this time, the ON period of the IGBT 10E is lengthened.

  Further, when the control calculation unit 11 detects and determines the voltage with the DC voltage detection unit 6, if the decrease amount of the DC link voltage for each power supply cycle detected from the DC voltage detection unit 6 is small, the DC voltage detection unit 6 outputs DC from the smoothing capacitor 5. It is determined that the current supply to the brushless motor 8 is small. At this time, the ON period of the IGBT 10E is lengthened.

  Further, when the adjustment of the phase period is determined by the output command to the DC brushless motor 8 controlled by the control calculation unit 11 itself, the PWM control signal is set so as to reduce the duty ratio of the PWM pulse to the IGBTs 7A to 7F. Is output, the current supply from the smoothing capacitor 5 to the DC brushless motor 8 is determined to be small.

  At this time, the control calculation unit 11 performs control so as to lengthen the ON period of the IGBT 10E. In this case, the ON period of the IGBT 10E is not adjusted after the current or voltage is detected, but the ON period is adjusted at the same time as the control is started so as to reduce the output to the DC brushless motor 8. The resulting control delay can be prevented, and as a result, the period during which the performance of the motor drive device is reduced can be shortened.

  In addition, you may perform ON operation of IGBT10E in multiple times. In this case, as shown in FIG. 4, the ON period of the IGBT 10E is 10 to 85 degrees and 90 to 110 degrees when the half cycle of the power supply voltage phase is 360 degrees.

  In the simulation waveform of FIG. 4, the power supply current increases rapidly in each period. However, the peak value of the current can be suppressed by performing the ON operation a plurality of times as described above. Furthermore, it is possible to improve the degree of freedom for adjusting the ON period according to the purpose of emphasizing the power factor and the average voltage amount.

[Second Embodiment]
Next, a second embodiment of the present invention will be described using FIG. 5 and FIG. In addition, the same code | symbol is attached | subjected to the same part as 1st Embodiment, description is abbreviate | omitted, and a different part is demonstrated.

  As shown in FIG. 5, the overall configuration of the motor drive device of the second embodiment is the same as that of the first embodiment except that the variable means includes a snubber circuit 20.

  The snubber circuit unit 20 includes a diode 20A, a resistor 20B, and a capacitor 20C, and suppresses a surge voltage when the IGBT 10E is turned off. Diode 20A has its anode side connected to the collector of IGBT 10E and its cathode side connected to capacitor 20C. The other end of the capacitor 20C is connected to the emitter of the IGBT 10E. The resistor 20B is connected in parallel with the diode 20A.

  Next, the operation of the motor driving device in the above circuit configuration, particularly the operation of the short circuit 10 and the snubber circuit unit will be described.

  In the positive half cycle of the AC power supply 1, the AC current output from the AC power supply 1 flows in the order of reactor 2A → diode 10A → IGBT 10E → diode 10D → reactor 2C if the IGBT 10E is turned on.

  At the moment when the IGBT 10E is turned off, the alternating current flows through the reactor 2A → the diode 10A → the diode 20A → the capacitor 20C → the diode 10D → the reactor 2C, and then flows through the reactor 2A → the reactor 2B → the reactor 2C and becomes a steady state. At this time, the electric charge charged in the capacitor 20C flows through the resistor 20B when the IGBT 10E is turned on in the next half cycle, and flows from the IGBT 10E → the diode 10D → the reactor 2C.

  FIG. 6 shows simulation waveforms of the power supply voltage, DC link voltage, and power supply current during these operations. The constants of the components in the simulation waveform according to the present embodiment are 20Ω for the resistor 20B and 39 μF for the capacitor 20C. Others are the same as in the first embodiment. In order to set the average output of the motor drive device to 1500 W, the inverter circuit 7 and the DC brushless motor 8 are set to a constant current source of DC 6.3 A. The ON period of the IGBT 10E is set to 10 to 85 degrees when the half cycle of the power supply voltage is set to 360 degrees.

  As is apparent from the comparison of the power supply current waveforms shown in FIGS. 6 and 2, the snubber circuit 20 reduces the peak current change at the moment when the IGBT 10E is turned OFF, and the current decreases gently. Therefore, since the generation of the surge voltage is alleviated, the noise caused by this is reduced, and the malfunction of the peripheral portion of the circuit can be avoided.

  For the purpose of suppressing the surge voltage, the required capacity of the capacitor 20C of the snubber circuit 20 is generally given by the following equation (1).

Required capacity of capacitor = La · Ia ² / (Va−Ea) ² (1)
Here, La is the stray inductance of the circuit, Ia is the collector current when the IGBT is turned off, Va is the final value of the capacitor voltage (forward breakdown voltage between the collector and emitter of the IGBT), and Ea is the voltage applied to the snubber circuit. Show.

  If it is about the output of the present embodiment, La is about 0.2 μH, and Ia / (Va−Ea) is 0.5 or less at most, so the required capacity of the capacitor 20C in the usual case is about 0.47 μF. Become.

  However, in this embodiment, by using 39 μF which is sufficiently larger than usual, the current change becomes very gentle as shown in FIG. Therefore, the power factor can be improved. However, when discharging the accumulated charge in the capacitor 20C, the power consumption in the resistor 20B increases.

  As a result, sudden current fluctuation at the end of the short-circuit operation of reactors 2A to 2C and generation of surge voltage due to stray inductance are alleviated, so that noise caused by this is reduced, and malfunction of the peripheral portion can be avoided. it can. Further, by making the capacitance of the capacitor 20C of the snubber circuit 20 larger than usual, the current fluctuation at the end of the short circuit operation becomes more gentle, so that the power supply utilization rate is increased and the power factor is improved.

  Here, in a compressor used in a refrigeration / air-conditioning apparatus or the like, the amount of current required to drive the DC brushless motor 8 that is a compressor driving device is large, so the voltage drop of the smoothing capacitor 5 is accelerated. Therefore, it is necessary to speed up the recovery of the voltage of the smoothing capacitor 5. Therefore, the motor driving device provided with the DC power supply device is used to drive the DC brushless motor 8 which is a compressor driving device. As a result, the power factor is improved and a large amount of power can be supplied even with a limited power source capacity in the home. And the compressor drive device provided with this motor drive device is mounted in an air conditioner. As a result, the air conditioner can be operated.

  In addition, this invention is not limited to the said embodiment, Of course, correction and a change can be added within the scope of the present invention. For example, three reactors are connected in series in consideration of symmetry, but the same effect can be obtained if there are two or more reactors.

  Further, although the short circuit is constituted by the IGBT and the diode, a simple configuration may be adopted by a switching element having a sufficient reverse breakdown voltage or an element capable of flowing a current in both directions.

  Moreover, although the motor drive device provided with the DC power supply device of the present invention is mounted on the air conditioner, it may be mounted on a refrigeration / air conditioning device such as a refrigerator or a freezer. In addition, the DC power supply device may be operated on other electric devices. By installing the DC power supply device, the power supply utilization efficiency is increased and the power factor can be improved.

1 is a circuit diagram of a motor drive device according to a first embodiment of the present invention. Operation waveform diagram of DC power supply device provided in motor drive device Waveform diagram of conventional DC power supply Operational waveform diagram when the variable means operation is performed twice in the DC power supply device provided in the motor drive device The circuit diagram of the motor drive device concerning a 2nd embodiment of the present invention. Operation waveform diagram of DC power supply device provided in motor drive device Circuit diagram of conventional motor drive device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2A-2C Reactor 3 Rectifier diode bridge 3A-3D Diode 4A, 4B Voltage doubler capacitor 5 Smoothing capacitor 6 DC voltage detection part 6A, 6B Resistance 7 Inverter circuit 7A-7F IGBT
7G-7L Freewheel diode 8 DC brushless motor 9 Current detection part 10 Short circuit 10A-10D Diode 10E IGBT
10F free wheel diode 11 control arithmetic unit 12 current 20 snubber circuit 20A diode 20B resistor 20C capacitor 30 AC power supply 31 reactor 32 rectifier diode bridge 33, 34 voltage doubler rectifier capacitor 35 smoothing capacitor 36 inverter circuit 37 control circuit 38 motor A DC power supply C switching circuit

Claims (3)

Rectifying means for rectifying AC voltage from an AC power supply to generate DC voltage, smoothing means for smoothing the rectified DC voltage, and a plurality of reactors connected in series between the AC power supply and the rectifying means, A DC power supply device having
A variable means for varying the reactor capacity; and a control means for controlling the variable means; the rectifying means is provided with a charge storage means; and the control means is a voltage of the AC power supply during a half cycle of the AC voltage. In accordance with a timing when the voltage exceeds the voltage of the charge storage means, the variable means is operated so that the reactor capacity becomes small . 2. The DC power supply apparatus according to claim 1, wherein the control means performs the operation of the variable means a plurality of times while the voltage of the AC power supply exceeds the voltage of the charge storage means during a half cycle of the AC voltage. . A motor drive device comprising the DC power supply device according to claim 1 or 2 and inverter means for converting a smoothed DC voltage into AC of a variable frequency,
The air conditioner characterized in that the control means includes a motor drive device that operates the variable means according to the output from the inverter means to the motor.

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