JP2001238454A - Power supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power loss in the power supply apparatus for full-wave rectification and boosting of voltage. SOLUTION: A power supply apparatus 42 is provided with a bridge rectifying circuit 50 using a diode 48, a voltage-boost circuit 78 using a reactor 54, a switching transistor Tr 74 and diodes 60, 62 for boosting the voltage and is also provided with a bypass circuit 90 for connecting the reactor and a smoothing circuit 64. The bypass circuit is provided with a power MOSFET 92 and, when this power MOSFET 92 is turned on in the predetermined timing, a power bypassing the bridge rectifying circuit and voltage-boost circuit is outputted. As a result, power loss by diode is reduced to improve power conversion efficiency.

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. Specifically, the present invention relates to a power supply device provided with a bridge rectifier circuit and a booster circuit.

[0002]

2. Description of the Related Art Some air conditioners (air conditioners) that perform cooling and heating by a refrigerating cycle change the number of revolutions of a rotary compressor when adjusting the 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 drive (rotation speed) of the compressor is controlled using an inverter circuit.

[0003] PAM (Puls
Some use e Amplitude Modulation (pulse amplitude modulation) control. The power supply device used for the PAM control is provided with a booster circuit using a chopper circuit or the like in addition to the bridge rectifier circuit. The booster circuit converts the power rectified by the bridge rectifier circuit into power of a desired voltage. ing.

The booster circuit includes a reactor element, a boost diode, a switch element, and a capacitor. After the power is stored in the reactor element by turning on / off the switching element, the power is charged in the capacitor. At this time, a desired voltage can be obtained by controlling the ratio (duty ratio) of the ON time of the switching element. In such a power supply device, by controlling the timing of switching the switching element,
The power factor can be improved and harmonics can be suppressed.

Incidentally, a diode used in a bridge rectifier circuit or a booster circuit causes a considerable voltage drop (for example, about 0.75 V). This voltage drop appears as power loss, and the loss increases as the output power increases. In a power supply device used for PAM control or the like, a diode is provided in each of the bridge rectifier circuit and the booster circuit, and there is a problem that power conversion efficiency is reduced due to loss caused by the diodes.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to propose a power supply device that improves power conversion efficiency by suppressing power loss.

[0007]

According to the present invention, there is provided a rectifying circuit for performing full-wave rectification by using a diode in which AC power is connected in a bridge, and a reactor provided on the AC power supply side of the rectifying circuit. A power supply device comprising: a switching element provided on an output side of the rectifier circuit; and a switching circuit configured by a diode, wherein the power output from the switching circuit is smoothed and converted into DC power. A bypass circuit including a power MOSFET as a switching element capable of supplying an output of the reactor element to the smoothing circuit by bypassing a diode forming the rectifier circuit and a diode forming the switching circuit. The power MOSFET is turned on / off at a predetermined timing. A scan driving unit, characterized by comprising a.

According to the present invention, rectification and boosting of an alternating current are performed using a rectifying circuit for performing full-wave rectification and a boosting circuit to output DC power of a predetermined voltage. At this time, a rectifier circuit formed by bridge connection of diodes is used as the rectifier circuit, and a booster circuit is provided with a switching element, and a desired voltage is obtained by turning on / off the switching element.

The bypass circuit uses a power MOSFET having a very low forward voltage drop and a high withstand current and withstand voltage as compared with a rectifying diode.
The reactor element and the smoothing circuit are connected by the SFET.

By turning on the power MOSFET at a predetermined timing, the power stored in the reactor can be bypassed to the diode of the rectifier circuit and the diode of the booster circuit. At this time, since the power MOSFET has an extremely low voltage drop, the power loss can be reduced and the input power can be output efficiently.

According to the present invention, there is provided a zero cross point detecting means for detecting a zero cross point at which the phase of the AC voltage is inverted, and the bypass driving means detects the power MOSFE of the bypass circuit based on the detection result of the zero cross detecting means.
T may be used as long as it turns on / off the T. When the switching element of the booster circuit is off, the bypass driving means operates the power MOSFET of the bypass circuit.
Turn on T.

Power is stored in the reactor element by switching the switching element of the booster circuit, and this power is stored in the capacitor by turning off the switching element. At this time, by turning on the power MOSFET, the loss can be reduced and the power can be efficiently stored and output to the smoothing circuit.

The bypass circuit includes a plurality of power MOSs.
More preferably, the FETs are connected in parallel.

By connecting a plurality of power MOSFETs in parallel, the forward resistance value when the power MOSFETs are turned on decreases, and power loss in the bypass circuit can be reduced.

In the present invention, the bypass circuit may include a diode connected in parallel to the power MOSFET. Further, it is preferable to use, as the diode, a diode whose current direction is the forward direction with respect to the power MOSFET and a diode whose current direction is the reverse direction.

Even if only the diode is used, the power stored in the reactor element can be stored in the smoothing circuit without passing through the diode of the rectifier circuit and the diode of the booster circuit.
By connecting T in parallel, power loss in this diode can be suppressed and power conversion efficiency can be improved.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 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 the valve 20A of the outdoor unit 14,
It is connected to the four-way valve 24 via the muffler 22A.
The four-way valve 24 includes an accumulator 28 and a muffler 2
It is connected to the compressor 26 via 2B.

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 refrigeration cycle is configured between the indoor unit 12 and the outdoor unit 14.

In the air conditioner 10, when the compressor 26 is operated by rotation of a compressor motor 40 provided integrally with the compressor 26, the refrigerant circulates through the refrigeration cycle. At this time, in the air conditioner 10,
The four-way valve 24 is switched according to the operation mode (cooling mode or heating mode), and the valve opening of the electric expansion valve 36 is controlled to adjust the evaporation temperature of the refrigerant. In FIG. 2, the 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 cooling mode, the refrigerant compressed by the compressor 26 is liquefied by being supplied to the heat exchanger 30, and the liquefied refrigerant is vaporized in 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 passes through a heat exchanger 18 to regulate the temperature when blowing air sucked by a cross flow fan (not shown) provided for air blowing into a room. Thereby, the room is air-conditioned by the air blown from the indoor unit 12.

On the other hand, as shown in FIG. 1, the outdoor unit 14 is provided with a compressor motor 40, a power supply device 42 for driving the compressor motor 40, and a control board 44 having a microcomputer (not shown). As the compressor motor 40, for example, a sensorless type direct current (DC) brushless motor is used, and the power supply device 42 converts AC power supplied to the outdoor unit 14 into
It is converted into DC power used for driving the compressor motor 40, and the DC power is
Supply 0.

On the control board 44, a microcomputer is connected by a serial communication or the like so that signals can be transmitted / received to / from a microcomputer (not shown) provided in the indoor unit. The control board 44 is connected to 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 the like.

Thus, the microcomputer provided on the control board 44 can control the compressor motor 40, the four-way valve 24, the conductive expansion valve 36, the heat exchanger based on the signal sent from the indoor unit 12 and the detection result of each sensor. 30
The drive of a cooling fan etc. which blows air to is controlled. The microcomputer of the control board 44 is a compressor motor 4
When the operation of the compressor motor 40 is controlled, the power supply device 42 and the inverter circuit 46 are controlled so that the compressor motor 40 is driven to rotate at a predetermined rotational speed.
The voltage to be applied to is controlled.

The microcomputer provided on the control board 44 controls the duty ratio of the switching signal for driving the switching element provided in the inverter circuit 46, and the switching element is driven by this switching signal, whereby the inverter circuit 46 Outputs power of a voltage (output voltage V ₀ ) corresponding to the duty ratio of the switching signal. With this electric power, the compressor motor 4
By driving 0, the compressor 26 is operated at the rotation speed set by the microcomputer of the control board 44.

The power supply 42 is provided with a bridge rectifier circuit 50 in which a diode 48 is bridge-connected.
This bridge rectifier circuit 50 has one input terminal 52A.
Is connected to the reactor 54. As a result, AC power of a predetermined voltage (for example, single-phase 100 V) is input from the AC power supply 56 to the power supply device 42 to the input terminals 52A and 52B of the bridge rectifier circuit 50 via the reactor 54.

In the bridge rectifier circuit 50, a smoothing circuit 64 is connected to output terminals 58A and 58B via diodes 60 and 62 for boosting. Output terminal 58A
The diode 60 connected to the output terminal 58B has a current flowing in a direction from the bridge rectifier circuit 50 to the smoothing circuit 64.
The current direction from the smoothing circuit 64 to the bridge rectifier circuit 50
It is a direction toward.

The smoothing circuit 64 is formed by capacitors 66 and 68 directly connected and a capacitor 70 connected in parallel to the capacitors 66 and 68. A diode 60 is connected to the + side of the capacitors 66 and 70. The negative sides of the capacitors 68 and 70 are connected to the diode 62.

Further, the power supply 42 has a diode 6
0, 62 (the output terminal 58 of the bridge rectifier circuit 50).
A and 58B), a switching circuit 72 is provided. The switching circuit 72 includes an IGBT (Insulated Gate Bipolar Transistor) as a switching element.
r) and the like, and is formed by a switching Tr 74 and a diode 76. When the switching Tr 74 is turned on, a current flows from the output terminal 58A to the output terminal 58B.

Thus, the reactor 54 provided with the bridge rectifier circuit 50 interposed therebetween,
A boosting circuit 78 is formed by the switching circuit 72, the diodes 60 and 62, and the smoothing circuit 64. After the AC power is rectified by the bridge rectifier circuit 50, the AC power is boosted by switching (on / off) of the switching Tr 74 and output. At this time, the output voltage V ₀ depends on the ON time of the switching signal for driving the switching Tr 74.
Can be changed.

On the other hand, the control substrate 44 includes a switching Tr7 of the control circuit 80 and the switching circuit 72.
4 is formed. Further, the power supply device 42 is provided with a current detection circuit 84 and a zero-cross detection circuit 86, which are connected to the control circuit 80.

The current detection circuit 84 is connected to a CT 88 provided between the reactor 54 and the AC power supply 50. Further, the zero-cross detection circuit 86 is connected to the reactor 54.
The input terminal 52B of the bridge rectifier circuit 50 is connected to the AC power supply 56 side. Thereby, the control circuit 80
, A zero-cross signal based on the current and voltage waveforms input to the power supply device 42 is input.

The control circuit 80 sets the duty ratio of the switching signal based on the input current detected by the current detection circuit 84, and sends the switching signal to the drive circuit 82 at a timing based on the zero-cross point detected by the zero-cross detection circuit 86. Is output. This allows the power supply device 42 to output the predetermined output voltage V0, improve the power factor of the input power, and remove harmonic components from the input AC power. The control circuit 8
At 0, a period outside the audible frequency of 15 kHz or more (for example, 1
The switching of the switching Tr 74 is performed at 7 kHz).

For example, FIG. 3 (A), FIG. 3 (B), FIG.
As shown in FIG. 3 (C) and FIG.
Are set to output the switching signals ST _{1 to} ST ₄ (see FIG. 3C) in one cycle of the AC power supply 50. At this time, the control circuit 80, (delay of e.g. time t ₁₎ input voltage allowed to send slightly from the detection of the zero-cross point P ₁ to change to the positive side from the negative side to output the switching signal ST _1, the input voltage There outputs a switching signal ST ₂ to stop before (eg, time t ₂₎ to reach the zero-cross point P ₂ which changed to negative from positive. Further, the control circuit 80 outputs a switching signal ST ₃ when the input voltage reaches a zero-cross point P _2, the switching signal to stop before (eg, time t ₃₎ the input voltage reaches a zero-cross point P ₁ ST ₄ Is output.

In such a control circuit 80, the switch
Signal ST₁~ ST_FourIs the time at which is output
Time t_Four, T_Five, T₆, T₇Mainly the output power of the power supply 42.
Pressure V ₀And the switching signal ST₁~ ST
_FourThe duty ratio (ON time) of the current detection circuit 8
4 is set based on the input current detected.

At this time, the switching signals ST ₁ , S
The duty ratio of T ₃ is, switching signals ST _2, ST ₄
The duty is set to be shorter than the duty. Further, the control circuit 80 controls the switching signal ST ₁
Between switching signal ST ₂ and switching signal S
Among of T ₃ and the switching signal ST _4, it is provided with a switching downtime.

The switching start and stop by the switching signals ST _{1 to} ST ₄ may be performed by setting a phase angle of the AC voltage and performing a time based on the phase angle. In the switching signals ST ₁ and ST ₃ , the time and duty ratio of the preceding stage are set in advance, the duty ratio of the succeeding stage is set based on the input current, and the time of the succeeding stage is set based on the output voltage V _0. There may be.

Thus, as shown in FIG. 3 (E), in the power supply 42, the input current is increased near the zero cross points P ₁ and P ₂ , and the phase of the input current is adjusted to the phase of the input voltage. The power factor can be improved (for example, 0.97 or more), and the input current can be smoothly changed to remove harmonic components from the AC power.

The air conditioner 10 thus configured
When an operation condition such as an operation mode and a set temperature is set by operating a remote control switch (not shown), and a start of operation is instructed by operating a start / stop button, a microcomputer (not shown) provided in the indoor unit 12 operates. The air conditioning capacity required for air-conditioning the room is calculated according to the set operating conditions, and the rotation speed of the compressor motor 40 is set based on the calculation result. Thereafter, the microcomputer provided in the indoor unit 12 controls the outdoor unit 1 to drive the compressor motor 40 at the set rotation speed.
4 to the control board 44.

In the control board 44 provided in the outdoor unit 14, the internal microcomputer controls the power supply 42 and the inverter circuit 46 so that the rotation speed of the compressor 26 specified by the microcomputer of the indoor unit 12 can be obtained.
, The compressor motor 40 is rotationally driven. Thereby, in the air conditioner 10, 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.

At this time, the outdoor unit 1 of the air conditioner 10
In No. 4, in addition to the PWM control using the inverter circuit 46, the PAM control for controlling the rotation speed of the compressor 26 is performed by changing the output voltage of the power supply 42 input to the inverter circuit 46.

By the way, as shown in FIG.
2 is provided with a bypass circuit 90. The bypass circuit 90 includes a power MOS as a switching element.
FET (Power Metal Oxide Semiconductor Field Effe
ct Transistor) 92.

The power MOSFET 92 is formed by connecting a large number of fine pattern MOSFET cells in parallel, and is capable of flowing a large current with a high withstand voltage. The power MOSFET 92 has a drain D-source S
When a bias voltage is applied between the gate G and the source S, a forward voltage drop of the damper diode 94 becomes extremely low (about 0.3 V or less).

The control board 44 is provided with a MOSFET drive circuit 96 as bypass drive means. The MOSFET drive circuit 96 is connected to the control circuit 80. The control circuit 80 outputs a zero cross signal detected by the zero cross detection circuit 86 to the MOSFET drive circuit 96.

The MOSFET drive circuit 96 supplies the power MOSF of the bypass circuit 90 based on the zero cross signal.
ET92 is driven. In the present embodiment, the control circuit 80 outputs a zero-cross signal to the MOSFET drive circuit 96. However, the zero-cross detection circuit 86
And the MOSFET drive circuit 96, and a zero-cross signal may be output from the zero-cross detection circuit 86 to the MOSFET drive circuit 96.

At this time, as shown in FIG.
The SFET drive circuit 96 switches the switching signal (ON signal) ST ₅ when the switching Tr 74 is off and at the timing when the power accumulated in the reactor 54 passes through the power MOSFET 92 and flows to the smoothing circuit 64.
And the power MOSFET 92 is turned on.

Thus, when the power MOSFET 92 is turned on, the power stored in the reactor 54 does not pass through the diode 48 of the bridge rectifier circuit 50 and the diode 62 (60) of the booster circuit 78, and the bypass circuit 9
The signal passes through 0 and is stored in the smoothing circuit 64.

Generally, in the diodes 48, 60, 62, etc., a considerable power loss occurs. For this reason, the output power is lower than the input power, and the power use efficiency is reduced. That is, a voltage drop of about 0.75 V per rectifier diode occurs. This voltage drop is
Power loss occurs, and the power loss increases as the current passing through the diodes 48, 60, and 62 increases.

On the other hand, in the power supply device 42, a power MOSFET 92 is connected between the reactor 54 and the smoothing circuit 64.
The diode 48 of the bridge rectifier circuit 50 and the diodes 60 and 62 of the booster circuit 78 can be bypassed. Thus, a voltage drop when a current flows between the reactor 54 and the smoothing circuit 64 is suppressed, and the power conversion efficiency is improved. That is, when the input power and the output voltage are the same, the output power decreases due to the voltage drop in the diodes 48, 60 (62) and the like.
By bypassing 2), a decrease in output power due to a voltage drop can be suppressed.

(Embodiment 1) FIG. 4 shows one embodiment of a bypass circuit (bypass circuit 90) with one power MO.
1 shows a bypass circuit 100 using an SFET 92. The bypass circuit 100 includes a power MOSFET 9
Two drains D are connected together with the reactor 54 to the input terminal 52A of the bridge rectifier circuit 50. The source S of the power MOSFET 92 is connected to the capacitor 6 provided in the smoothing circuit 64 together with the diode 62 of the booster circuit 78.
8 (70) is connected to the negative side. That is, when the power MOSFET 92 is turned on, it becomes possible to conduct electricity in the forward direction with the diode 62 of the booster circuit 78.

As shown in FIG. 3D, the MOSFET drive circuit 96 is in a state where the switching Tr 74 of the booster circuit 78 is off without switching and the diode 62 of the booster circuit 78 is in the forward direction. in becomes the timing, outputs a switching signal (oN signal) ST _5, turns on the power MOSFET 92.

As a result, power is stored in the smoothing circuit 64 without passing through the diode 48 of the bridge rectifier circuit 50 and the diode 62 of the booster circuit 78, and the stored power is supplied to the inverter circuit 46 serving as a load. Is output. Therefore, in the power supply device 42, the power loss is suppressed as compared with the case where the power passing through the bridge rectifier circuit 50 and the booster circuit 78 is stored and output. That is, when the output voltage is the same, the output power substantially equal to the input power is obtained, and the power conversion efficiency can be improved.

The power supply 42 can reduce the loss of power in this way, and can efficiently output the input power. In particular, in the air conditioner 10, when the capacity of the compressor 26 increases, the power supply device 42 requires a large output power. When a large output power is required, the power loss due to the diode increases. However, in the air conditioner 10 provided with the power supply device 42 including the bypass circuit 90, the power loss can be significantly reduced and the air conditioning operation can be performed. it can.

Here, the experimental results of the power conversion efficiency will be described using the reference example shown in FIG. 5 and the second and third embodiments of the bypass circuit shown in FIGS. 6 and 7.

(Reference Example) FIG. 5 shows a power supply unit 42A as a reference example. This power supply device 42A includes a power MOSFET between a reactor 54 and a smoothing circuit 64.
Rectifier diodes 104, 1 provided in pairs without using
06 is provided.

One end of each of the diodes 104 and 106 is connected to the input terminal 52A of the bridge rectifier circuit 50. The other end of the diode 104 is connected to the + side of the capacitor 66 (70) provided in the smoothing circuit 64, and the current direction (forward direction) is the reactor 54.
The other diode 106 is connected to the negative side of the capacitor 68 (70) provided in the smoothing circuit 64, and the forward direction becomes the reactor 54 from the smoothing circuit 64. It is provided as follows.

As a result, in the power supply device 42A, the electric power stored in the reactor 54 passes from the reactor 54 through the diode 104 to the capacitor 66 (the smoothing circuit 6).
The current flows to the + side of 4) and is accumulated, and the current flows from the-side of the capacitor 68 to the reactor 54 through the diode 106.

Thus, the reactor 54 and the smoothing circuit 6
4, the diode 48 of the bridge rectifier circuit 50 and the boosting diode 60 or the diode 6
2, the power is stored and released through the diode 60 or the diode 62.

Therefore, in the power supply device 42A, the diode 48 of the bridge rectifier circuit 50 and the diodes 60 and 62 of the booster circuit 78 are bypassed by the diode 104 or the diode 106. Thus, power loss is reduced.

(Embodiment 2) FIG. 6 shows a power supply unit 42B according to Embodiment 2. The bypass circuit 108 provided in the power supply device 42B includes a diode 104,
106 and one power MOSFET 92.

Power MOSFET of bypass circuit 108
The drain 92 is connected to the input terminal 52A of the bridge rectifier circuit 50, and the source S is connected to the negative side of the capacitor 68 (smoothing circuit 64). That is, they are connected in parallel with the diode 106 with the forward direction coincident with the diode 106.

Thus, in the second embodiment, the power MOS
While the FET 92 is off, the diodes 104, 1
06 bypasses the diode 48 of the bridge rectifier circuit 50 and the diodes 60 and 62 of the booster circuit 78, and turns on the power MOSFET 92.
(Diode 48 of bridge rectifier circuit 50, booster circuit 7
8 is bypassed to reduce the power loss.

Third Embodiment FIG. 7 shows a power supply device 42C according to a third embodiment. The bypass circuit 110 provided in the power supply device 42C includes a diode 104,
106 and a plurality (six) of power MOSFETs 92.

Power MOSFET of bypass circuit 110
Each of 92 is connected in parallel with diode 106 so as to be in the forward direction with diode 106.

Thus, in the third embodiment, as in the second embodiment, while the power MOSFET 92 is turned off, the diodes 104 and 106 use the diodes 48 of the bridge rectifier circuit 50 and the diodes 60 and 6 of the booster circuit 78.
By bypassing the power MOSFET 2 and turning on the power MOSFET 92, the power MOSFET 92 allows the diode 106 (the diode 4 of the bridge rectifier circuit 50) to be turned on.
8. Diode 62 and diode 10 of booster circuit 78
6) is bypassed to reduce power loss.

In the bypass circuit 110, by connecting six power MOSFETs 92 in parallel, the internal resistance causing a voltage drop is reduced to about 1/6, so that the power loss can be further reduced. ing.

Table 1 shows the reference example, the second embodiment and the third embodiment.
3 shows the measurement results of the power conversion efficiency in FIG. Also,
FIG. 8 shows a change in the efficiency τ with respect to the input current Ii.

[0070]

[Table 1]

The efficiency τ is τ = (Pi / Po) × 100 (%), and the input voltage Vi is the voltage of the AC power supply 56 and the input current I
i uses the current flowing through the reactor 54, and the output power Po
Is the power consumed by the load (inverter circuit 46). In addition, as shown in FIG.
Drive circuit 96 drives the power MOSFET92 (on), performed between the time t _10, 2m from the zero-cross point P ₂
It starts after sec (time t ₈ = 2 msec) and reaches the zero cross point P ₁
2 msec (time t ₉ = 2 msec) before reaching.

As described above, in the reference example, the power loss is reduced by providing the bypass circuit 102 using the diodes 104 and 106, but as shown in the second and third embodiments, By providing the MOSFET 92, the efficiency τ can be further improved.

Further, as shown in the second and third embodiments, by connecting six power MOSFETs 92 in parallel as compared with the case where one power MOSFET 92 is provided,
Further, the efficiency τ can be improved.

In the present embodiment described above, the power MOS is mainly set so as to be in the forward direction with the diode 106.
Although the FET 92 is provided, the power MOSFET 92 may be provided so as to be in the forward direction with respect to the diode 104. In this case, the timing for turning on the power MOSFET 92 may be between the switching signals ST ₁ and ST ₂ .

The power MOSFET 92 may be provided in each of the diode 104 and the diode 106 so as to be in the forward direction.

The embodiment described above does not limit the configuration of the present invention. The present invention is not limited to the air conditioner 10 that performs PAM control, and can be applied to an air conditioner that includes a power supply device having an arbitrary configuration that performs voltage doubler rectification and boosting. Further, the present invention is not limited to the air conditioner,
The present invention can be applied to a power supply device having an arbitrary configuration for performing voltage doubler rectification and boosting.

[0077]

As described above, according to the present invention, a power MOSFET is used in a bypass circuit that bypasses a diode of a rectifier circuit and a diode of a booster circuit, and the power MOSFET is turned on at a predetermined timing, so that rectification is performed. Power loss due to the diode can be reduced. As a result, an excellent effect of improving the power conversion efficiency and enabling efficient operation of a load such as a compressor using the input electric power is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a power supply device applied to the present embodiment.

FIG. 2 is a schematic diagram showing a refrigeration cycle of an air conditioner to which the power supply device of the present embodiment is applied.

FIGS. 3A to 3E are diagrams with a horizontal axis representing a time axis, FIG. 3A is a diagram showing an example of an input voltage to a power supply device,
(B) is a diagram showing a switching signal output based on an input voltage, (C) is a diagram showing a switching signal for driving a switching Tr of a booster circuit, and (D) is a diagram for driving a power MOSFET of a bypass circuit. FIG. 3E is a diagram illustrating a switching signal, and FIG. 3E is a diagram illustrating an input current obtained by switching at the timing of FIG.

FIG. 4 is a block diagram illustrating a schematic configuration of a power supply device provided with a bypass circuit according to the first embodiment.

FIG. 5 is a block diagram illustrating a schematic configuration of a power supply device applied as a reference example.

FIG. 6 is a block diagram illustrating a schematic configuration of a power supply device provided with a bypass circuit according to a second embodiment.

FIG. 7 is a block diagram illustrating a schematic configuration of a power supply device provided with a bypass circuit according to a third embodiment.

FIG. 8 is a diagram based on Table 1 showing a comparison of efficiency with respect to input current in the reference example and the second and third embodiments.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Air conditioner 14 Outdoor unit 26 Compressor 40 Compressor motor 42, 42B, 42C Power supply 44 Control board 46 Inverter circuit 48 Diode 50 Bridge rectification circuit 54 Reactor 56 AC power supply 60, 62 Diode 64 Smoothing circuit 66, 68, 70 Capacitor 72 Switching circuit 80 control circuit 90, 100, 108, 110 bypass circuit 92 power MOSFET 96 MOSFET drive circuit (bypass drive means)

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) DC02 DC04 DC05 5H560 AA02 BB05 DC12 DC20 EB01 GG04 JJ13 RR04 SS07 UA06 XA12

Claims (6)

[Claims] 1. A rectifier circuit for full-wave rectification of AC power by a diode connected in a bridge, a reactor element provided on an AC power supply side of the rectifier circuit, and a switching element provided on an output side of the rectifier circuit. A switching circuit configured by a diode and a switching circuit configured to smooth the power output by the switching circuit and convert the power to DC power, a diode forming the rectifier circuit, and the switching circuit. A bypass circuit including a power MOSFET as a switching element capable of supplying an output of the reactor element to the smoothing circuit by bypassing a diode that forms a bypass circuit; and a bypass drive for turning on / off the power MOSFET at a predetermined timing. Means, and a power supply device characterized by comprising: . 2. A zero-crossing detecting means for detecting a zero-crossing point at which a phase of an AC voltage is inverted, wherein said bypass driving means turns on / off a power MOSFET of said bypass circuit based on a detection result of said zero-crossing detecting means. The power supply device according to claim 1, wherein: 3. The power supply device according to claim 2, wherein the bypass drive unit turns on a power MOSFET of the bypass circuit when a switching element of the booster circuit is turned off. 4. The power supply according to claim 1, wherein the bypass circuit includes a plurality of power MOs.
The power supply device according to any one of claims 1 to 3, wherein SFETs are connected in parallel. 5. The power MOSF according to claim 1, wherein
The power supply device according to any one of claims 1 to 4, further comprising a diode connected in parallel to the ET. 6. The power supply device according to claim 5, wherein the diodes of the bypass circuit include a diode whose current direction is a forward direction and a diode whose current direction is a reverse direction to the power MOSFET.