JP2000014153A - Power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a stable output voltage, suppressing a boosting ratio even when an AC voltage is low. SOLUTION: In a rectifying circuit 46, the contact 84A of a relay 84 is connected between an input terminal 58B of a rectifier 56 and the junction 65 of capacitors 64, 66. A microcomputer 44 opens the contact of the relay, when an AC voltage Vi is 200 V, and forms a full-wave rectifier circuit. But it closes the contact of the relay and forms a voltage doubler rectifier circuit, when the AC voltage is 100 V. Consequently, it becomes possible to obtain an output voltage Vd the same as that obtained when the AC voltage is 200 V, even when it is 100 V, and it becomes unnecessary to increase the boosting ratio of a boosting circuit 48 for obtaining an output voltage V0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply for converting AC power into DC power. More specifically, the present invention relates to a power supply device that converts AC power into DC power of a desired voltage by a rectifier circuit and a booster circuit, and performs inverter control of a motor using the DC power.

[0002]

2. Description of the Related Art Some air conditioners (air conditioners) which perform cooling and heating by a refrigerating cycle change the number of revolutions of a compressor when adjusting cooling and heating capacity. That is, in the air conditioner, the cooling / heating capacity is reduced by reducing the rotation speed of the compressor, and the cooling / heating capacity is increased by increasing the rotation speed of the compressor. In such an air conditioner, the control range of the number of rotations of the compressor, that is, the control range of the operating frequency of the compressor motor is expanded, so that the control range of the cooling and heating capacity can be increased.

On the other hand, when a DC motor is used as a compressor motor in an air conditioner, a booster circuit is provided to control the number of revolutions of the compressor motor, and the DC voltage supplied to the compressor motor is changed by the booster circuit. .

In general, a booster circuit includes a reactor (inductance element), a switching device, and a diode, and turns on the switching device. Thereby, the electric circuit on the output side of the reactor is short-circuited, DC power is supplied to the reactor, and after the energy is stored in the reactor, the switching device is turned off. Thus, the input DC voltage is boosted to a predetermined voltage by adding the voltage generated in the reactor to the input voltage and charging the capacitor.

At this time, by controlling the ratio of the on time of the switching device (duty ratio or conduction ratio), the waveform and current value of the AC input current input to the rectifier circuit at the preceding stage of the booster circuit are controlled. Thus, the DC voltage output together with the power factor improvement can be controlled. Such output voltage control is performed by PAM (Puls
e Amplitude Modulation (pulse amplitude modulation) control is performed.

By the way, by using a rectifier circuit and a booster circuit, P
By performing the AM control, the input AC voltage becomes
Not only 200V but also 100V is possible.

However, when the input AC voltage is 10
At 0 V, it is necessary to increase the step-up ratio in order to obtain a predetermined output voltage (for example, DC 280 V) by the step-up circuit, which increases the load on the switching device and the reactor, and increases the size of the power supply device. This leads to an increase in product costs.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and is a power supply device which is low in cost and can obtain a stable output even if the input AC voltage is 200 V / 100 V. The purpose is to propose.

[0009]

The invention according to claim 1 is
A diode is formed in a bridge connection, a rectifier circuit that double-wave rectifies alternating-current power supplied from a pair of input terminals and outputs from a pair of output terminals, and a power output from a pair of output terminals of the rectifier circuit. A booster circuit for boosting and outputting a voltage; at least two capacitors connected in series between a pair of output terminals of the rectifier circuit for smoothing rectified power; a connection point between the two capacitors; It is provided between one of the input terminals.
Switching means for connecting between the plurality of capacitors and one of the input terminals.

According to the present invention, a bridge type double-wave rectifier circuit is formed by opening the switching means. Further, by closing the switching means, a double-wave rectification type voltage doubler rectifier circuit is formed. Thereby, for example, when the power supply voltage is 20
When the opening / closing means is opened at 0 V and when the power supply voltage is 1
The output voltage is substantially the same as when the switching means is closed at 00V.

Therefore, when the power supply voltage is 100 V, the boosting ratio when boosting to a predetermined voltage does not increase, and even when the power supply voltage is low, the reactor and the switching device of the booster circuit need to have a low cost. It can be used, and a desired output voltage can be obtained without having to increase the step-up ratio.

[0012] The invention according to claim 2 is characterized in that it includes voltage detecting means for detecting the input voltage, and the switching means is opened and closed based on the detection result of the voltage detecting means.

According to the present invention, the detecting means for detecting the voltage of the AC power serving as the power supply is provided, and the opening and closing means is opened and closed based on the detection result of the detecting means.

Thus, for example, when the AC voltage is 200 V
In this case, the switching means can be opened and the switching means can be closed when the AC voltage is 100 V, and the output voltage to the booster circuit can be kept substantially constant.

According to another aspect of the present invention, there is provided a rectifier circuit formed by bridge-connecting a diode, performing dual-wave rectification on AC power supplied from a pair of input terminals, and outputting the rectified power from a pair of output terminals. At least two capacitors connected in series between output terminals of the rectifying circuit, and provided between a connection point of the two capacitors and one of a pair of input terminals of the rectifier circuit. Opening / closing means that opens when the voltage of the AC power is equal to or higher than a predetermined value, a reactance and a switching element that are sequentially connected in series between output terminals of the rectifier circuit, and a diode that is sequentially connected in series to the switching element in order And a smoothing capacitor, wherein a load is connected to both ends of the smoothing capacitor.

According to this invention, when the voltage of the AC power is equal to or higher than the predetermined value, the switching means is opened to perform the double-wave rectification, and when the voltage is equal to or lower than the predetermined value, the switching means is closed to perform the voltage doubler rectification. It is. The capacitor is charged by accumulating / discharging energy in a reactance by turning on / off the switching element, and a charging voltage is applied to the load.

At this time, even if the voltage of the AC power is low, power of a desired voltage can be supplied to the load without increasing the step-up ratio.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a refrigeration cycle of an air conditioner (hereinafter, referred to as “air conditioner 10”) applied to the present embodiment.

The air conditioner 10 includes an indoor unit 12 installed in a room to be air-conditioned and an outdoor unit 1 installed outside the room.
The indoor unit 12 and the outdoor unit 14 are formed by a thick refrigerant pipe 16 for circulating a refrigerant.
A and the refrigerant pipe 16B of a thin tube.

The indoor unit 12 is provided with a heat exchanger 18, and one end of each of the refrigerant pipes 16A and 16B is connected to the heat exchanger 18. The other end of the refrigerant pipe 16A is connected to a valve 20A of the outdoor unit 14. This valve 20A has a muffler 22A
Is connected to the four-way valve 24 via the. This four-way valve 24
Is connected to the compressor 26 via the accumulator 28 and via the muffler 22B.

Further, the outdoor unit 14 is provided with a heat exchanger 30. One end of the heat exchanger 30 is connected to the four-way valve 24 and the other end is connected to the capillary tube 32.
Valve 20 via strainer 34 and modulator 38
B. An electric expansion valve 36 is provided between the strainer 34 and the modulator 38, and the other end of the refrigerant pipe 16B is connected to the valve 20B.
Thereby, a closed circulation path of the refrigerant forming a refrigeration cycle is formed between the indoor unit 12 and the outdoor unit 14.

In the air conditioner 10, when the compressor 26 is operated by the rotational drive of a compressor motor 40 provided integrally with the compressor 26, the refrigerant circulates through the refrigeration cycle, thereby enabling the cooling and heating operation. In FIG. 2, arrows indicate the flows of the refrigerant during the heating operation (heating mode) and during the cooling operation (cooling mode or dry mode).

In the air conditioner 10, the four-way valve 24 is switched according to the operation mode (cooling mode or heating mode),
By controlling the valve opening of the electric expansion valve 36, the evaporation temperature of the refrigerant is adjusted.

In the cooling mode, the refrigerant compressed by the compressor 26 is liquefied by being supplied to the heat exchanger 30, and the liquefied refrigerant is evaporated by the heat exchanger 18 of the indoor unit 12, thereby exchanging heat. The air passing through the vessel 18 is cooled. In the heating mode, on the contrary,
The refrigerant compressed by the compressor 26 releases heat by being condensed in the heat exchanger 18 of the indoor unit 12, and heats the air passing through the heat exchanger 18 with the heat released by the refrigerant.

The indoor unit 12 is provided with a cross flow fan for blowing air, and the air sucked by the indoor unit 12 passes through the heat exchanger 18 and is blown into the room by the cross flow fan. . The room is air-conditioned by the blowing air. As shown in FIG. 1, the outdoor unit 14 is provided with a power supply 42 for driving the compressor motor 40 and a microcomputer 44 for controlling the rotation of the compressor motor 40 by controlling the power supply 42.

The microcomputer 44 is connected to a microcomputer (not shown) provided in the indoor unit 12 by, for example, serial communication or the like, and operates based on a signal from the microcomputer of the indoor unit 12.

The outdoor unit 14 includes an outside air temperature sensor for detecting the outside air temperature, a compressor temperature sensor for detecting the temperature of the compressor 26, a coil temperature sensor for detecting the coil temperature of the heat exchanger 30, and a heat exchanger 30. A cooling fan or the like for cooling is provided.
4 and a motor for operating the motor-operated expansion valve 36 and the like are connected to the microcomputer 44. The microcomputer 44 controls the operation of the outdoor unit 14 based on a signal from the microcomputer of the indoor unit 12 and a detection result of each sensor.

The power supply 42 provided in the outdoor unit 14 includes a rectifier circuit 46 and a booster circuit 48.
The AC power supplied from the AC power supply 50 to the rectifier circuit 46 is output from the booster circuit 48 to the inverter circuit 52. The compressor motor 40 is driven to rotate by the electric power output from the inverter circuit 52.

The rectifier circuit 46 is provided with a rectifier 56 in which diodes 54 are connected in a bridge shape. The choke coils 6 are connected to input terminals 58A and 58B of the rectifier 56.
0, an AC power supply 50 is connected. The outdoor unit 14 of the air conditioner 10 applied to the present embodiment is operated by supplying single-phase 100V or single-phase 200V AC power from an AC power supply 50.

Between the output terminals 62A and 62B of the rectifier 56, capacitors 64 and 66 having the same capacitance are connected in series. As a result, the AC power is subjected to double-wave rectification by the rectifier circuit 56, and then smoothed by the capacitors 64 and 66 and output to the booster circuit 48.

The booster circuit 48 has a general configuration including a reactor 68, a switching transistor (switching Tr 70), a diode 72, and a capacitor 74. In the booster circuit 48, the rectifying circuit 46 is connected to the reactor 68, which is an inductance element, by turning on the switching Tr 70, which is a switching element.
The DC power output from flows through to store energy. Thereafter, when the switching Tr 70 is turned off, a voltage corresponding to the energy stored in the reactor 68 is added to the DC power voltage output from the rectifier circuit 46 and the capacitor 74 is charged. The voltage charged in the capacitor 74 is output as a boosted output voltage V0.

The switching Tr 70 is connected to the microcomputer 44 via a drive circuit 76, and is turned on / off by a switching signal output from the microcomputer 44. At this time, the microcomputer 44 controls the ratio (duty ratio or conduction ratio) of the ON time of the switching Tr 70 of the booster circuit 48, thereby controlling the output voltage V of the booster circuit 70.
Controls 0. That is, the microcomputer 44 controls a PAM (Pulse Amplitude Modulation) that controls the output voltage V0 (the amplitude of the output voltage) according to the ON time of the switching signal.
: Pulse amplitude modulation) control.

In the power supply unit 42, the switching T
By controlling the range of the phase angle at which r70 is turned on, it is possible to control the input current and the waveform from the AC power supply 50 that are input to the rectifier circuit 46 in the preceding stage of the booster circuit 48. The microcomputer 44 controls the switching Tr 70 based on the phase of the input voltage (AC voltage) and the input current (AC current) to the rectifier circuit 46, thereby improving the power factor.

That is, a power supply voltage detection circuit 78 and a power supply current detection circuit 80 are connected to the microcomputer 44. The microcomputer 44 uses the power supply voltage detection circuit 78 and the power supply current detection circuit 80 to control the voltage of the AC power supply 50. The phase is detected together with the current, and the switching Tr 70 is controlled based on the detection result.

At this time, for example, FIG.
As shown in (B), the microcomputer 44 controls the AC voltage V
When a phase signal based on i is read and a zero-cross point of the AC voltage is detected from the phase signal, a predetermined timing (for example, when the phase angle θ is
７０70 °), the switching signal ST1 is output. As the switching signal ST1, for example, a pulse of 17 kHz is used, and the pulse width is controlled so that a predetermined output voltage V0 is obtained.

The switching signal ST1 is stopped when a zero cross of the alternating current Ii is detected.

As shown in FIG. 3 (E), the current (reactor current) Li flowing through the reactor 68 increases in value when the switching signal ST1 is output, and the change in the current value causes the current Li to increase. As shown in (D), the AC current Ii can be changed, thereby changing the phase of the AC current. Thus, the phases of the AC voltage Vi and the AC current Ii can be made coincident with each other according to the timing of the switching signal ST1.

The microcomputer 44 adjusts the operation start timing of the switching Tr 70 with respect to the AC voltage Vi to improve the power factor (for example, about 0.94 to 0.9).
7). Thereby, the electric power can be efficiently used in the outdoor unit 14. The control of the current waveform and the power factor using the booster circuit 48 and the like can use a conventionally known general method, and a detailed description thereof will be omitted in the present embodiment.

By the way, as shown in FIG. 1, the output voltage V0 of the booster circuit 48 is input to the inverter circuit 52, and the compressor motor 40 is driven by the power output from the inverter circuit 52. The inverter circuit 52 is connected to the microcomputer 44, and turns on / off a switching element provided in the inverter circuit 52 according to a switching signal ST2 output from the microcomputer 44.

As the compressor motor 40, a DC brushless motor is used, and the number of revolutions changes according to a change in input voltage. Therefore, a voltage corresponding to the duty ratio of the switching signal is output from the inverter circuit 52 to the compressor motor 40, and the compressor motor 40 is driven to rotate at a rotation speed corresponding to this voltage. The output voltage of the inverter circuit 52 can be changed according to the output voltage V0 of the booster circuit 48 when the switching signal ST2 is fixed.

That is, the microcomputer 44 controls the rotation speed of the compressor motor 40 by PWM control and PAM control.

The microcomputer 44 includes a compressor motor 40
In the region where the number of rotations is low, the output voltage V0
Is maintained at a predetermined value, and the rotation speed of the compressor motor 40 is controlled by the PWM control. In a region where the rotation speed of the compressor motor 40 is high and exceeds the range of the PWM control, the output voltage V0 of the booster circuit 48 causes the compressor motor 4 to rotate.
PAM control for controlling the number of revolutions of 0 is performed. The microcomputer 44 includes a compressor motor 40
A rotation speed detection circuit 82 for detecting the rotation speed of the compressor motor 40 is connected, and the feedback control is performed so that the rotation speed of the compressor motor 40 detected by the rotation speed detection circuit 82 becomes a desired rotation speed.

As described above, in the air conditioner 10, by using the PWM control and the PAM control, the control range of the rotation speed of the compressor motor 40 is expanded while maintaining the optimum power factor. The air conditioning operation can be performed with an appropriate air conditioning capacity according to the indoor air conditioning state.

On the other hand, the rectifier circuit 46 is provided with a relay 84 as opening / closing means. The relay 84 has a contact 84A connected to one input terminal 58B of the rectifier circuit 46 and a connection point 65 between the capacitors 64 and 66. The coil 84B of the relay 84 is connected to the microcomputer 44, and the relay 84 is driven by the microcomputer 44 to open and close the contact 84A.

The microcomputer 44 detects the voltage of the AC power supply 50 by the power supply voltage detection circuit 78. When the voltage of the AC power supply 50 is 100V, the microcomputer 44 drives the relay 84 to switch the contact 8
Close 4A.

As shown in FIG. 4A, the rectifier circuit 4
6, when the contact 84A of the relay 84 is open,
The bridge-connected diode 54 forms a double-wave rectifier circuit. Also, as shown in FIG.
When the relay 84 is driven and the contact 84A is closed, the rectifier circuit 46 connects the input terminal 58B with the capacitor 6A.
A connection point 65 between the terminals 4 and 66 is connected to form a voltage doubler rectifier circuit.

As a result, as shown in FIG. 5, the output voltage Vd of the rectifier circuit 46 varies between when the AC voltage is 200V and the contact 84A is open, and when the AC voltage is 100V and the contact 84A is closed. Become the same, about 260V ~
A voltage of 280 V is output.

The booster circuit 48 boosts the output voltage Vd of the rectifier circuit 46 to about 300 V or more and outputs it.

The operation of this embodiment will be described below.

The air conditioner 10 is provided in the indoor unit 12 when operating conditions such as an operating mode and a set temperature are set by operating a remote control switch (not shown), and an operation start is instructed by operating a start / stop button. When a microcomputer (not shown) calculates the air-conditioning capacity necessary for air-conditioning the room according to the set operating conditions, the microcomputer sets the rotation speed of the compressor motor 40 based on the calculation result. Thereafter, the microcomputer provided in the indoor unit 12 operates the microcomputer 4 provided in the outdoor unit 14 so as to drive the compressor motor 40 at the set rotation speed.
Instruct 4

The microcomputer 44 drives the compressor motor 40 while controlling the booster circuit 48 and the inverter circuit 52 so that the rotation speed of the compressor 26 specified by the microcomputer of the indoor unit 12 is obtained. As a result, in the air conditioner 10, the refrigerant compressed by the compressor 26 is circulated in the refrigeration cycle, and regulates the temperature of the air passing through the heat exchanger 18 provided in the indoor unit 12. The air whose temperature has been adjusted by passing through the heat exchanger 18 of the indoor unit 12 is blown out of the indoor unit 12, thereby achieving indoor air conditioning.

Before the compressor motor 40 starts operating, the microcomputer 44 starts to operate the power supply voltage detecting circuit 78.
Thus, the voltage (AC voltage) of the AC power supply 50 input to the power supply device 42 is detected, and the relay 84 is driven based on the detection result. Thus, when the voltage of the AC power supply 50 is 200V, the microcomputer 44
The fourth contact 84A is opened. As a result, as shown in FIG. 4A, the rectifier circuit 46 becomes a dual-wave rectifier circuit by the bridge-connected diode 54 and the capacitors 64 and 66. After the AC voltage is double-wave rectified, it is smoothed. , Output voltage Vd to booster circuit 48.

On the other hand, when the voltage of the AC power supply 50 is 100 V, the microcomputer 44 drives the relay 84 to close the contact 84A. Thereby, as shown in FIG. 4B, the rectifier circuit 46 becomes a double voltage double-wave rectifier circuit by the diode 54 and the capacitors 64 and 66, and the AC voltage is double-voltage double-wave rectified and then smoothed. Then, it is output to the booster circuit 48 as the output voltage Vd.

As shown in FIG. 5, the output voltage Vd is substantially the same when the AC voltage of 200 V is double-wave rectified and when the AC voltage of 100 V is double-wave rectified.
The rectifier circuit 46 can output the same output voltage Vd regardless of whether the AC voltage of the AC power supply 50 is 200 V or 100 V.

The boosting circuit 48 receives an input voltage (output voltage Vd) according to a switching signal ST1 from the microcomputer 44.
Output a predetermined voltage V0 or a voltage higher than the predetermined voltage V0. At this time, for example, when the input voltage is low, the boost ratio becomes higher than when the input voltage is high, in order to obtain a predetermined output voltage V0 (for example, 300 V).

In order to increase the step-up ratio, it is necessary to store a large amount of energy in the reactor 68 by lengthening the ON time of the switching Tr 70. For this reason, since a large current flows through the switching Tr 70 and a large current flows when the reactor 68 releases energy, it is necessary to use large and expensive parts.
As a result, the size of the power supply device 42 may be increased.

On the other hand, in the rectifier circuit 46 applied to the present embodiment, when the input AC voltage is low,
Since the voltage doubler rectification is performed, the same output voltage Vd as when the AC voltage is high is obtained, and it is not necessary to increase the boost ratio of the booster circuit 48 even when the voltage of the AC power supply 50 is low. This eliminates the need to use expensive and large-capacity components for the switching elements and reactance (inductance elements) provided in the booster circuit 48, and reduces the flowing current value, so that relatively small and inexpensive components can be used. .

Therefore, even if the configuration is such that a predetermined output voltage V0 is always obtained, the cost and size can be reduced, and a stable output voltage V0 can be obtained. Also,
The compressor motor 40 can be driven with a stable voltage, and the compressor 26 is driven at a stable rotation speed, so that the air conditioning capacity of the air conditioner 10 can be appropriately controlled.

In this embodiment, the relay 84 is used as the opening / closing means. However, the opening / closing means applied to the present invention is not limited to this. An element may be used, or mechanical opening / closing means such as a switch for opening / closing an electric circuit by manual operation may be used. Further, the configuration may be such that a desired output voltage is obtained by performing phase control using a semiconductor device such as a triac, not limited to a relay.

This embodiment does not limit the configuration of the present invention. In the present embodiment, the air conditioner 10
However, the air conditioner to which the present invention is applied can be applied as long as it controls the rotation speed of the compressor motor 40 with an inverter. Further, in the present embodiment, an air conditioner has been described as an example, but the present invention can be applied to any power supply device provided with a booster circuit.

[0061]

As described above, according to the present invention, a voltage doubler rectifier circuit can be formed by opening and closing switching means, so that the boosting ratio of the boosting circuit can be reduced even when a low voltage AC power supply is connected. There is no need to raise it. This provides an excellent effect that the booster circuit can be formed at low cost and with small components.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of a power supply device to which the present invention is applied.

FIG. 2 is a schematic configuration diagram illustrating a refrigeration cycle of an air conditioner applied to the present embodiment.

3A is a diagram illustrating an AC voltage waveform, FIG. 3B is a diagram illustrating an example of a phase signal of the AC voltage, and FIG. 3C is a diagram illustrating a switching signal output according to the AC voltage and the AC current; (D) is a diagram showing an example of the waveform of the alternating current,
(E) is a diagram showing a current flowing through the reactor of the booster circuit.

FIGS. 4A and 4B are schematic wiring diagrams showing a rectifier circuit applied to the present embodiment, respectively, wherein FIG. 4A shows a state in which a relay contact is opened, and FIG. The state where the contact was closed is shown.

FIG. 5 is a diagram showing an AC voltage input to the rectifier circuit and an output voltage output from the rectifier circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Air conditioner 14 Outdoor unit 26 Compressor 40 Compressor motor 42 Power supply device 44 Microcomputer 46 Rectifier circuit 48 Boost circuit 50 AC power supply 52 Inverter circuit 54 Diode 58A, 58B Input terminal 62A, 62B Output terminal 64, 66 Capacitor 68 Reactor 78 Power supply voltage detection circuit 84 relay (opening / closing means)

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 5H006 AA02 BB05 CA01 CA07 CB01 CB04 CB09 CC02 DA04 DB02 DB07 DC02 DC04 DC05 DC07 HA08 5H576 AA10 BB03 BB10 CC05 DD02 DD07 EE11 EE19 EE30 GG02 HA02 HA08 HB01 LL23 LLLL 5H730 AA18 AS04 BB14 BB86 CC01 DD02 EE07 FD11 FD41 FD61 FG05 FG06 FG12 FV09

Claims (3)

[Claims] 1. A rectifier circuit formed by bridge-connecting diodes, rectifying both sides of AC power supplied from a pair of input terminals and outputting the rectified power from a pair of output terminals, and a pair of output terminals of the rectifier circuit. A booster circuit for boosting and outputting the output power; at least two capacitors connected in series between a pair of output terminals of the rectifier circuit for smoothing the rectified power; and connection of the two capacitors A power supply device provided between a point and one of the pair of input terminals, and a switching means for connecting between the two capacitors and one of the input terminals by closing a contact. 2. The power supply device according to claim 1, further comprising voltage detection means for detecting the input voltage, wherein the switching means is opened and closed based on a detection result of the voltage detection means. 3. A rectifier circuit formed by bridge-connecting a diode, rectifying both sides of AC power supplied from a pair of input terminals and outputting the rectified power from a pair of output terminals, and a pair of output terminals of the rectifier circuit. At least two capacitors connected in series between the two capacitors to smooth the rectified power; and a connection point between the two capacitors and one of a pair of input terminals of the rectifier circuit, the Opening / closing means that opens when a voltage is equal to or higher than a predetermined value; a reactance and a switching element sequentially connected in series between output terminals of the rectifier circuit; a diode and a smoothing capacitor sequentially connected in series to the switching element in series And a load connected to both ends of the smoothing capacitor.