CN1592067A - Power supply device and air-conditioner using the same - Google Patents

Abstract

To provide a power supply device capable of stable operations, without being affected by the fluctuations in the AC power supply voltage, and provide an air conditioner. The power supply device is provided with an AC power supply voltage detecting part (41) for detecting the voltage of the AC power supply (1); a zero-cross detection part (21), which detects the zero-cross point of the AC power supply voltage, on the basis of the detected voltage of the AC power supply and outputs a zero-cross detecting signal; a pulse signal control part (22) which generates and outputs a pulse signal for turning on/off switching elements (4a, 4b) of a power factor improving circuit (7), on the basis of the zero-cross detecting signal; and a switch driving part (23) which drives each switching element of the power factor improving circuit (7) by receiving the pulse signal. The zero-cross detecting part includes a timer (21a), which outputs the zero-cross detecting signal, after the elapse of a delay time (td) from the time when the AC power supply voltage reaches a prescribed voltage, and a correction part (21b) for correcting the delay time (td), based on the AC power supply voltage.

Description

Power supply unit and air conditioner using the same

technical field

The invention relates to a power supply device, in particular to a power supply device using a DC voltage variable function of a power factor improving circuit. In addition, the present invention also relates to an air conditioner using the power supply unit.

Background technique

Conventionally, as an AC-DC conversion circuit, a capacitive-input type rectifier circuit in which an AC voltage is input to a diode rectifier circuit to obtain a pulse output and smoothed by a capacitor to obtain a DC voltage has been used in various fields.

When a capacitor-input type rectifier circuit is used in a power supply device, the power factor deteriorates due to the narrow current conduction angle of the input current, and there is a large amount of reactive power. Therefore, there is a problem that effective power cannot be used. In addition, the input current contains many high-frequency components, which poses a problem of damage to devices connected to the same power supply system. Therefore, a power supply device has been developed that improves the power factor and reduces high-frequency components (see, for example, Patent Document 1).

The circuit structure of this power supply device is shown in FIG. 8 . The power supply device shown in FIG. 8 has a circuit configuration for converting an AC voltage Vin input from an AC power supply 101 into a pulse output voltage through a rectifier circuit 103, and a reactor 102 is inserted into this circuit configuration. The reactor 102 alleviates the impact of the input current Iin. As a result, the current conduction angle can be widened, the power factor can be improved, and the high-frequency components included in the input current Iin can be reduced.

For example, when the power supply device is used in an air conditioner (air-conditioner), the load 105 is a motor for a compressor and an inverter for driving the motor. In this power supply device, when the AC power supply 101 is 100V, the relay circuit 130 is usually turned on to operate as a voltage doubler rectifier circuit. The wave rectification circuit works to reduce the output DC voltage. In this case, losses in the inverter and the motor can be reduced.

As described above, the conventional power supply unit shown in FIG. 8 can improve the power factor while suppressing the loss of the load 105 by switching the energization state of the relay circuit 130 only by inserting passive devices (reactors) with a simple structure.

In addition, another example is a power supply device having a circuit configuration shown in FIG. 9 (refer to Patent Document 2). The detailed operation of this power supply device will be described below.

In FIG. 9, the rectification circuit 133 and the switching device 131 constitute a power factor improvement circuit. The control unit 132 outputs a pulse signal for turning on the switching device 131 at a predetermined time in synchronization with the zero-cross point of the AC power supply 101 . In this way, since a current short-circuiting the AC power supply 101 flows through the reactor 102 via the rectifier circuit 133 and the switching device 131 , the input power flows from the zero-cross point of the AC power supply 101 . Thus, when the switching device 131 is turned off, a current flows through the reactor 102 , the rectifier circuit 103 , and the capacitors 120 a , 120 b or the smoothing capacitor 104 . As a result, the current conduction angle can be enlarged, and the power factor can be greatly improved.

When this power supply unit is used in an air conditioner, the load 105 is also a compressor motor and an inverter for driving the motor. Also in the low-load region, by turning off the relay circuit 130 to form a full-wave rectifier circuit, losses in the inverter and the motor can be reduced.

As described above, the conventional power supply device shown in FIG. 9 can greatly improve the power factor by simple configuration and control, and can suppress the loss of the load 105 by switching the energized state of the relay circuit 130 .

<Patent Document>

Patent Document 1: Japanese Unexamined Patent Publication No. 9-182457

Patent Document 2: Japanese Unexamined Patent Application Publication No. H11-206130

In the power supply circuit of the configuration shown in FIG. 9, when it is detected that the input voltage value of the AC power supply Vin becomes lower than a predetermined voltage, it is judged as a zero-cross point, and after a predetermined time elapses from the zero-cross point, the output power is output. A pulse signal in which the switching device 131 of the factor improving circuit is turned on for a given time.

However, in this method, if the input voltage Vin of the AC power source fluctuates, the zero-crossing detection point will also be misaligned, so that the switching device 131 cannot be turned on at the correct timing, resulting in low efficiency of the power factor improvement circuit.

In addition, the input voltage value of the power factor improvement circuit will decrease due to the fluctuation of the power supply voltage Vin or the increase of the load. Therefore, the set value of the output voltage of the power factor improving circuit is set to the maximum possible value so as not to be affected even when the output power decreases due to fluctuations in the power supply voltage or loads. The pulse signal output time during which the switching device of the power factor improving circuit is turned on is set to the maximum value. However, if the maximum value of the pulse signal output time during the conduction period of the switching device as the power factor improving circuit is set to be large, an overcurrent will flow in the power factor improving circuit. Conversely, if the maximum value of the pulse signal output time (on time) is set to be small in order to avoid overcurrent, the DC output voltage of the power factor improvement circuit cannot be sufficiently raised when the input power of the AC power source is reduced. voltage, leading to a reduction in the efficiency of the power supply unit.

Contents of the invention

In order to solve the above-mentioned problems, an object of the present invention is to provide a power supply device capable of stably outputting without being affected by fluctuations in AC power supply voltage, and an air conditioner using the power supply device.

The first power supply device related to the present invention includes a rectification circuit for rectifying the input voltage of the AC power supply, a reactor connected to the rectification circuit, and boosting the DC voltage rectified by the rectification circuit to make the input of the AC power supply A power factor improvement circuit in which the voltage waveform matches the input current waveform. The power factor improvement circuit includes a switching unit composed of a plurality of switching devices connected in series to turn on and off the current path of the input current flowing from the AC power supply, and a capacitor circuit composed of a plurality of capacitors connected in series, and The backflow prevention rectifier device prevents the charge charged on the capacitor from flowing back to the switch unit when the switch unit is turned on, and the switching switch unit switches the energized state of the current path to an on or off state. The switch unit is connected in parallel with the capacitance circuit, the contacts between the switch devices and the contacts between the capacitors are connected together, and the terminals of the switch unit and the terminals of the capacitor circuit are connected through the reverse current preventing rectification device. The changeover switch unit has one end connected to one point of the AC connection point of the rectifier circuit, and the other end connected to a connection point between switching devices of the power factor improving circuit.

In addition, the first power supply device further includes an AC power supply voltage detection device that detects the voltage of the AC power supply, and a zero-cross detection device that detects a zero-cross point of the AC power supply voltage and outputs a zero-cross detection signal based on the detected voltage of the AC power supply. device, and a pulse signal control device that generates and outputs a pulse signal that turns on/off each switching device of the power factor improvement circuit according to the zero-crossing detection signal, and a switch that receives the pulse signal and drives each switching device of the power factor improvement circuit drive unit. The zero-cross detection device is a timer unit that outputs a zero-cross detection signal after a given delay time (td) from when the AC power supply voltage reaches a given voltage, and according to the AC power detected by the AC power supply voltage detection device Voltage value, compensation unit for compensation delay time (td);

The first power supply device may further include DC detection means for detecting an output voltage of the power supply device. In this case, the pulse signal control device may change the conduction time (tw) of the switching device of the power factor improvement device according to the change of the voltage value detected by the DC voltage detection device. In addition, the pulse signal control device may change the maximum value of the conduction time (tw) of the switching device according to the value of the AC power supply voltage.

The second power supply device related to the present invention includes a rectification circuit for rectifying the input voltage of the AC power supply, a reactor connected to the rectification circuit, and boosting the DC voltage rectified by the rectification circuit, so that the AC power supply A power factor improvement circuit in which the input voltage waveform is consistent with the input current waveform. The power factor improvement circuit includes a switching unit composed of a plurality of switching devices connected in series to turn on and off the current path of the input current flowing from the AC power supply, and a capacitor circuit composed of a plurality of capacitors connected in series, and The backflow prevention rectifier device prevents the charge charged on the capacitor from flowing back to the switch unit when the switch unit is in the on state, and the switching switch unit switches the energized state of the current path to the on or off state. The switch unit is connected in parallel with the capacitance circuit, the contacts between the switch devices and the contacts between the capacitors are connected together, and the terminals of the switch unit and the terminals of the capacitor circuit are connected through the reverse current preventing rectification device. The changeover switch unit has one end connected to one point of the AC connection point of the rectifier circuit, and the other end connected to a connection point between switching devices of the power factor improving circuit.

In addition, the second power supply device further includes a DC power supply voltage detection device that detects the DC voltage output from the rectifier circuit, and a device that detects a zero-cross point of the AC power supply voltage based on the detected DC power supply voltage and outputs a zero-cross detection signal. A zero-cross detection device, and a pulse signal control device that generates and outputs a pulse signal for turning on/off each switching device of the power factor improvement circuit according to the zero-cross detection signal, and receives the pulse signal to drive each switch of the power factor improvement circuit device switching drive. A zero-cross detection device, including a timer unit that outputs a zero-cross detection signal after a given delay time (td) from when the DC power supply voltage reaches a given voltage, and a DC power supply detected by the DC power supply voltage detection device Voltage, compensation unit for compensation delay time (td);

The second power supply unit may further include DC detection means for detecting an output voltage of the power supply unit. The pulse signal control means can change the conduction time (tw) of the switching device of the power factor improving means according to the change of the voltage value detected by the DC voltage detecting means. In addition, the pulse signal control device may change the maximum value of the conduction time (tw) of the switching device according to the value of the DC power supply voltage.

A related air conditioner of the present invention includes the above-mentioned power supply device.

The present invention detects the input voltage (AC power supply voltage) from the AC power supply or the output voltage (DC power supply voltage) of the rectifier circuit, and by compensating the zero-cross detection delay time td based on the detected value, even if the input voltage of the AC power supply fluctuates, the The delay time td can be detected very accurately. Such a configuration is effective in improving the power factor because it can suppress fluctuations in the output DC voltage of the power factor improving circuit even if the input voltage of the AC power source fluctuates.

In addition, the AC power supply voltage or the DC power supply voltage can be detected, and the maximum value of the conduction time (tw) of the switching device of the power factor improvement circuit can be compensated according to the voltage. In this manner, fluctuations in the output voltage due to fluctuations in the input voltage from the AC power supply can be suppressed. Therefore, even if the voltage of the AC power source fluctuates, fluctuations in the output voltage of the power factor improving circuit can be suppressed and the power factor can be improved.

In addition, according to the present invention, it is possible to realize an air conditioner capable of maintaining high efficiency even if the input voltage of an AC power source fluctuates.

Description of drawings

FIG. 1 is a circuit configuration diagram of a power supply device according to Embodiment 1 of the present invention.

2 is a schematic diagram illustrating pulse signals and waveforms of main parts in the power supply device according to the first embodiment.

FIG. 3 is a diagram for explaining the timing of zero-cross point detection.

4 is a circuit configuration diagram of a power supply device according to Embodiment 2 of the present invention.

5 is a circuit configuration diagram of a power supply device according to Embodiment 3 of the present invention.

6 is a circuit configuration diagram of a power supply device according to Embodiment 4 of the present invention.

Fig. 7 is a configuration diagram of an air-conditioner using the power supply device of the present invention.

FIG. 8 is a circuit configuration diagram illustrating an example of a conventional power supply unit.

Fig. 9 is a circuit configuration diagram illustrating another example of a conventional power supply unit.

Detailed ways

The implementation of the related power supply device of the present invention will be described in detail below with reference to the accompanying drawings. In addition, the same reference symbols in the drawings indicate the same or equivalent constituent elements or parts.

(Embodiment 1)

FIG. 1 is a circuit configuration diagram of a power supply device according to Embodiment 1 of the present invention.

The power supply device includes a rectifier circuit 2 , a reactor 3 , a power factor improvement circuit 7 , a smoothing capacitor 8 and a changeover switch 12 .

The rectification circuit 2 includes a plurality of rectification elements 2a, 2b, 2c, and 2d, and rectifies the AC voltage Vin from the AC power supply 1 to output a pulse voltage. Reactor 3 is inserted for power factor improvement.

The power factor improving circuit 7 includes two switching devices 4 a and 4 b , two capacitors 5 a and 5 b , two reverse current preventing rectifying devices 6 a and 6 b and a switch 12 . Smoothing capacitor 8 smoothes the output voltage of power factor improving circuit 7 . A load 9 is connected to the power supply unit.

The switching switch 12 is connected between the connection point of the rectification devices 2b, 2d of the rectification circuit 2 and the connection point of the switching devices 4a, 4b of the power factor improvement circuit 7 . The changeover switch 12 is turned on and off to switch the energization state of the current path at the connection point to ON or OFF. The changeover switch 12 is constituted by a relay circuit as a mechanical switch or a semiconductor device as an electric switch. The power supply device basically performs a power factor improvement operation with a voltage doubler rectifier circuit when the switch 12 is closed, and basically performs a power factor improvement operation with a full-wave rectifier circuit when the switch 12 is open.

In the power factor improving circuit 7, the midpoint of the series connection of the two switching devices 4a, 4b is connected to the midpoint of the series connection of the two capacitors 5a, 5b. The switching device 4a is connected to the capacitor 5a via the backflow preventing rectifying device 6a. The switching device 4b is connected to the capacitor 5b via the backflow preventing rectifying device 6b.

The switching devices 4a and 4b are semiconductors capable of self-extinguishing arcs such as power triodes, power MOSFETs, and IGBTs. In addition, specific examples of the load 9 include a heating wire, an inverter, and a lighting device or a motor that operates connected to the inverter.

In addition, as components of the control system of the power supply device, a zero-cross detection unit 21 , a pulse signal control unit 22 , a switch drive unit 23 , a changeover switch drive unit 24 , and an AC power supply voltage detection unit 41 are included.

The AC power supply voltage detection unit 41 detects the power supply voltage Vin of the AC power supply 1 .

The zero-cross detection unit 21 detects the zero-cross point of the AC power supply 1 based on the signal from the AC power supply voltage detection unit 41 and outputs a zero-cross detection signal. The detection operation of the zero-cross point by the zero-cross detection unit 21 will be described in detail later.

The pulse signal control unit 22 receives the zero-cross detection signal from the zero-cross detection unit 21, generates and outputs a pulse signal for driving the switching devices 4a, 4b. The pulse signal control unit 22 can be constituted by a common logic circuit, a microcomputer, or the like. The switch driving part 23 receives the pulse signal from the pulse signal control part 22, and turns on/off the switching devices 4a and 4b. The changeover switch driving unit 24 drives the changeover switch 12 .

FIG. 2 shows respective waveforms of the power supply voltage, input current, and pulse signal in the power supply device of the present embodiment. The label "Vin" in the figure is the waveform of the AC power supply 1, and "Iin" is the waveform of the input current, and the direction indicated by the arrow is positive. Also, "Pa" represents a pulse signal for driving the switching device 4a, and "Pb" represents a pulse signal for driving the switching device 4b. In addition, "Va" and "Vb" represent the voltage across the capacitors 5a and 5b, respectively, and "Vdc" represents the voltage across the smoothing capacitor 8, that is, the output voltage of the power supply device.

The pulse signal control unit 22 outputs an output signal that is synchronized with the zero-cross point of the voltage Vin of the AC power supply 1 detected by the zero-cross detection unit 21 and turns on at least one of the switching devices 4a, 4b for a certain time (tw). state of the pulse signal. In the example of FIG. 2, the switching device 4a is turned on for a certain time (tw) in the positive half cycle of the AC power supply 1, and the switching device 4b is turned on for a certain time (tw) in the negative half cycle of the AC power supply 1. Pass. In addition, although not shown in the figure, the changeover switch 12 is turned on, for example, in synchronization with the respective conduction periods of the switching devices 4 a and 4 b.

In FIG. 2, when the switching device 4a is in the on state, since the voltage on the load 9 side is equal to the voltage Vb across the capacitor 5b viewed from the AC power source 1, the input current Iin begins when the voltage Vin exceeds the voltage Vb. It starts to flow and increases until the pulse signal Pa is in the conduction state.

Therefore, when the pulse signal Pa is turned off, the voltage on the load 9 side viewed from the AC power supply 1 becomes equal to the voltage Vdc across the smoothing capacitor 8. At this time, when the voltage Vin is smaller than the voltage Vdc, If the input current Iin decreases, the current to charge the capacitor 8 flows again from the moment the voltage value Vin exceeds the voltage Vdc across the smoothing capacitor 8 .

As a result, the rise of the input current Iin can be accelerated, and the current conduction period can be extended. Also in the negative half cycle, when the switching device 4b is turned on, the input current Iin starts to flow from the moment when the voltage value Vin exceeds the voltage Va across the capacitor 5a, so that the current conduction period can be extended.

By repeating the above-described operation in a half cycle of the AC voltage of the AC power supply 1, the current conduction period can be extended and a sufficiently high power factor can be obtained.

Next, the detailed operation of the zero-cross detection unit 21 will be described.

The zero-cross detection section 21 includes a timer 21a that outputs a zero-cross detection signal after a predetermined delay time (td) has elapsed since the voltage Vin of the AC power supply 1 reaches a set voltage Vth, and compensates for the output of the timer 21a. The delay time compensator 21b of the delay time td.

The zero-cross detection unit 21 receives a detected value of the AC power supply voltage Vin from the AC power supply voltage detection unit 41 and detects a zero-cross point of the AC power supply voltage Vin. Specifically, as shown in FIG. 3 , the timer 21 a of the AC power supply detection unit 21 compares the AC power supply voltage Vin with a given voltage (zero-cross judgment voltage) Vth, and detects when the input voltage Vin reaches the given voltage Vth. At timing t0, a zero-cross detection signal is output at timing tz obtained by delaying timing t0 by a delay time td.

Here, a case where the voltage value Vin drops to the voltage V'in and fluctuates is considered. In this case, since the timing at which the fluctuating voltage V'in reaches the given voltage Vth is t0', a zero-cross point deviated from the true zero-cross point is detected after a delay of the delay time td. Therefore, since the on/off operation of the switching devices 4a and 4b is not performed at the correct timing, the power factor improving circuit 7 does not operate correctly, resulting in deterioration of the power factor.

In this embodiment, in the zero-cross detection unit 21, the delay time compensation unit 21b compensates the delay time td according to the value of the AC power supply voltage Vin detected by the AC power supply voltage detection unit 41, so that even if the input value of the power supply voltage Vin occurs Variations, true zero crossings can also be detected. That is, the delay voltage compensator 21b monitors the amplitude of the power supply voltage Vin, and compensates for the delay time td according to the fluctuation of the amplitude value. For example, when the amplitude value (peak value) becomes smaller than the reference value, the delay time td is set to a larger value t'd. More specifically, the delay time compensation unit 21b performs compensation so that the compensated delay time t'd satisfies the following relational expression.

t'd=td+Δtd

Δtd=((reference value of AC power supply voltage-detection value of AC power supply voltage)/detection value of AC power supply voltage)×A×td

Here, A is the set compensation coefficient.

In this way, according to the power supply device of the present embodiment, since the delay time td for judging the zero cross is compensated according to the fluctuation of the voltage Vin of the AC power supply 1, it is possible to accurately detect The zero-cross point of the AC power supply voltage realizes the highly precise operation of the power factor improving circuit 7 .

(Embodiment 2)

FIG. 4 shows a circuit configuration diagram of Embodiment 2 of the related power supply device of the present invention.

The power supply device of the present embodiment further includes a DC detection unit 25 for detecting the output voltage Vdc of the power supply device in addition to the power supply device of the first embodiment. The output voltage of the smoothing capacitor 8 is detected as the output voltage Vdc, but the output voltage of the power factor improvement circuit 7 may also be detected. In addition, the pulse signal control unit 22 includes a maximum on-time compensation unit 22a for changing the maximum value of the on-time (tw) of the switching devices 4a and 4b according to the AC power supply voltage Vin.

The pulse signal control unit 22 changes the conduction time (tw) of the switching devices 4a and 4b according to the output voltage Vdc to obtain a constant output voltage value.

In particular, the pulse signal control unit 22 receives the detected value of the AC power supply voltage Vin from the AC power supply voltage detection unit 41 . If the AC power supply voltage decreases, the output voltage Vdc also decreases at the same time. Therefore, when the input voltage Vin of the AC power supply 1 is lowered, in order to suppress the fluctuation of the output voltage Vdc caused by it, the pulse signal control unit 22 increases the time tw during which the switching devices 4a and 4b are turned on, so that the output voltage Vdc becomes a certain voltage value.

However, if the switching devices 4a and 4b are turned on for a long time, the current flowing in the power factor improving circuit will also increase, which may damage the circuit, so the maximum value of the on time tw is set. The maximum value of the conduction time tw is set according to the rated value of the voltage of the AC power supply 1 . When the voltage Vin of the AC power source 1 decreases, even if the on-time tw increases to its maximum value, the desired output voltage value cannot be obtained.

Therefore, in this embodiment, the maximum on-time compensation unit 22a of the pulse signal control unit 22 increases the maximum value of the on-time tw when the AC power supply voltage Vin falls below the reference value (the rated value of the AC power supply voltage Vin). , making it larger than the value when the AC power supply voltage Vin is the rated value.

Also, when the input voltage Vin of the AC power supply 1 rises, the output voltage Vdc also rises, and the pulse signal control unit 22 reduces the conduction time tw of the switching devices 4a, 4b to keep the output voltage Vdc constant. At this time, the maximum on-time compensator 22a reduces the maximum value of the on-time tw to be smaller than the value when the AC power supply voltage Vin is a rated value.

As described above, the power supply device according to the present embodiment changes the maximum value of the conduction time tw of the switching devices 4a and 4b according to the fluctuation of the voltage Vin of the AC power supply 1, so that the maximum value of the conduction time tw of the switching devices 4a and 4b can be changed regardless of the change of the AC power supply voltage Vin. The value of the output voltage Vdc is kept constant.

(Embodiment 3)

FIG. 5 shows a circuit configuration diagram of Embodiment 3 of the related power supply device of the present invention.

The power supply device of the present embodiment includes a DC power supply voltage detection unit 51 for detecting the output voltage of the rectifier circuit 2 instead of the AC power supply voltage detection unit 41 in the power supply device of the first embodiment. The zero-cross detection unit 21 compensates for the delay time td based on the voltage value detected by the DC voltage detection unit 51 . That is, the timer 21a compares the DC output voltage (DC power supply voltage) output by the rectifier circuit 2 with a given voltage (zero-cross judgment voltage) Vth, and detects the timing t0 when the DC output voltage reaches the given voltage Vth, A zero-cross detection signal is output at a timing tz obtained by delaying this timing t0 by a delay time td. Other functions are the same as those in Embodiment 1.

Since the DC output voltage (DC power supply voltage) output by the rectifier circuit 2 fluctuates in response to fluctuations in the power supply voltage Vin of the AC power supply 1, the power supply device of this embodiment, like Embodiment 1, does not matter how the AC power supply voltage Vin is. The zero-crossing point of the AC power supply voltage can be accurately detected, and the operation of the power factor improvement circuit 7 with high precision can be realized.

(Embodiment 4)

FIG. 6 shows a circuit configuration diagram of Embodiment 4 of the related power supply device of the present invention.

The power supply device of the present embodiment further includes a DC detection unit 25 for detecting the output voltage Vdc of the power supply device in addition to the power supply device of the third embodiment. Also, the pulse signal control unit 22 includes a maximum on-time compensation unit 22a that changes the maximum value of the on-time (tw) of the switching devices 4a and 4b according to the AC power supply voltage Vin.

The pulse signal control unit 22 changes the conduction time (tw) of the switching devices 4a and 4b in order to obtain a constant output voltage value based on the output voltage Vdc.

The pulse signal control unit 22 receives the detected value of the DC power supply voltage as the output of the rectifier circuit 2 from the DC power supply voltage detection unit 51 . The pulse signal control unit 22 increases the time tw during which the switching devices 4a and 4b are turned on in order to suppress the fluctuation (decrease) of the output voltage Vdc caused by the decrease of the DC power supply voltage, so that the output voltage Vdc becomes a constant voltage. value.

The maximum on-time compensation unit 22a of the pulse signal control unit 22 increases the maximum value of the on-time tw to be greater than the value when the DC power supply voltage is at a rated value when the DC power supply voltage falls below a reference value.

In addition, when the DC power supply voltage rises above the reference value, the output voltage Vdc also rises. Therefore, when the DC power supply voltage rises, the pulse signal control unit 22 reduces the conduction time tw of the switching devices 4a, 4b to make the output voltage Vdc constant. At this time, the maximum on-time compensator 22a reduces the maximum value of the on-time tw to be smaller than the value when the AC power supply voltage Vin is a rated value.

As described above, the power supply device according to this embodiment changes the maximum value of the conduction time tw of the switching devices 4a and 4b in response to fluctuations in the DC power supply voltage, so that the output voltage can be maintained regardless of changes in the AC power supply voltage Vin. The value of Vdc is constant.

(Embodiment 5)

Next, a configuration example of an air conditioner using the power supply unit of the above-mentioned embodiment will be described.

FIG. 7 shows a configuration example of an air conditioner using the power supply unit described above. As shown in FIG. 7 , the air conditioner includes a power supply device 100 that converts the AC voltage Vin of the AC power supply 1 into a given DC voltage Vdc, and an inverter that generates a drive voltage for the motor 210 using the output of the power supply device 100 as a DC power supply. 200, and a refrigeration cycle 300 for performing indoor air conditioning by exchanging heat between indoor and outdoor air and refrigerant.

The power supply device 100 is any one of the power supply devices described in the above-mentioned embodiments.

The refrigeration cycle 300 includes an electric compressor 310 that compresses refrigerant circulating in the refrigeration cycle, an indoor heat exchange unit 320 , and an outdoor heat exchange unit 330 .

The electric compressor 310 is connected to the motor 210 and is driven by the motor 210 .

With the simple configuration and control of the power supply device according to the above embodiment, a sufficient power factor can be obtained, and the output voltage Vdc of the power factor improving circuit can be kept constant even if the voltage value of the AC power source fluctuates. Therefore, by using the output of such a power supply device as a power supply, it is possible to realize an air conditioner that operates efficiently and stably without being affected by fluctuations in the input voltage of the AC power supply.

Claims (5)

1. A power supply device, characterized in that, comprising: a) A rectification circuit for rectifying the voltage input by the AC power supply; b) A reactor connected to the above-mentioned rectification circuit; c) a power factor improving circuit that boosts the DC voltage rectified by the rectifier circuit so that the input voltage waveform of the above-mentioned AC power source is consistent with the input current waveform, The above-mentioned power factor improvement circuit includes: a switch unit composed of a plurality of switching devices connected in series to turn on or off the current path of the input current flowing from the above-mentioned AC power supply; a capacitive circuit composed of a plurality of capacitors connected in series ; when the switch unit is in a conduction state, a reverse flow prevention rectifier device that prevents the charge charged on the capacitor from flowing backward to the switch unit; The above-mentioned switch unit is connected in parallel with the capacitor circuit, the contacts between the above-mentioned switch devices and the contacts between the above-mentioned capacitors are connected together, the terminals of the above-mentioned switch unit and the terminals of the above-mentioned capacitor circuit are connected through the above-mentioned reverse current prevention rectifier device, and the switch unit has one end It is connected to one point of the AC connection point of the above-mentioned rectification circuit, and the other end is connected to the connection point between the switching devices of the above-mentioned power factor improvement circuit; d) an AC power supply voltage detection device for detecting the voltage of the AC power supply; e) a zero-cross detection device that detects a zero-cross point of the AC power supply voltage and outputs a zero-cross detection signal based on the detected voltage of the AC power supply, The above-mentioned zero-cross detection device includes: a timer unit that outputs a zero-cross detection signal after a given delay time (td) from when the AC power supply voltage reaches a given voltage; The voltage value of the AC power supply, the compensation unit for compensating the above-mentioned delay time (td); f) a pulse signal control device that generates and outputs a pulse signal that turns on/off each switching device of the above-mentioned power factor improvement circuit according to the above-mentioned zero-cross detection signal; g) A switch driving device for receiving the above-mentioned pulse signal and driving each switching device of the above-mentioned power factor improvement circuit. 2. The power supply device according to claim 1, characterized in that: It also includes: a DC detection device for detecting the output voltage of the above-mentioned power supply device, The above-mentioned pulse signal control device changes the conduction time (tw) of the switching device of the above-mentioned power factor improvement device according to the change of the voltage value detected by the above-mentioned DC voltage detection device; The value of the voltage changes the maximum value of the conduction time (tw) of the above switching device. 3. A power supply device, characterized in that it comprises: a) A rectification circuit for rectifying the voltage input by the AC power supply; b) A reactor connected to the above-mentioned rectification circuit; c) a power factor improving circuit that boosts the DC voltage rectified by the rectifier circuit so that the input voltage waveform of the above-mentioned AC power source is consistent with the input current waveform, The above-mentioned power factor improvement circuit includes: a switch unit composed of a plurality of switching devices connected in series to turn on or off the current path of the input current flowing from the above-mentioned AC power supply; a capacitive circuit composed of a plurality of capacitors connected in series ; when the switch unit is in a conduction state, a reverse flow prevention rectifier device that prevents the charge charged on the capacitor from flowing backward to the switch unit; The above-mentioned switch unit is connected in parallel with the capacitor circuit, the contacts between the above-mentioned switch devices and the contacts between the above-mentioned capacitors are connected together, the terminals of the above-mentioned switch unit and the terminals of the above-mentioned capacitor circuit are connected through the above-mentioned reverse current prevention rectifier device, and the switch unit has one end It is connected to one point of the AC connection point of the above-mentioned rectification circuit, and the other end is connected to the connection point between the switching devices of the above-mentioned power factor improvement circuit; d) a DC power supply voltage detection device for detecting the DC voltage output by the rectification circuit; e) a zero-cross detection device that detects a zero-cross point of an AC power supply voltage based on the detected DC power supply voltage and outputs a zero-cross detection signal, The above-mentioned zero-cross detection device includes: a timer unit that outputs a zero-cross detection signal after a given delay time (td) from when the AC power supply voltage reaches a given voltage; The voltage value of the AC power supply, the compensation unit for compensating the above-mentioned delay time (td); f) a pulse signal control device that generates and outputs a pulse signal that turns on/off each switching device of the above-mentioned power factor improvement circuit according to the above-mentioned zero-cross detection signal; g) A switch driving device for receiving the above-mentioned pulse signal and driving each switching device of the above-mentioned power factor improvement circuit. 4. The power supply device according to claim 3, characterized in that: It also includes: a DC detection device for detecting the output voltage of the above-mentioned power supply device, The pulse signal control device changes the conduction time (tw) of the switching device of the power factor improvement device according to a change in the voltage value detected by the DC voltage detection device, The value of the voltage changes the maximum value of the conduction time (tw) of the above switching device. 5. An air conditioner, characterized in that: It has the power supply device described in any one of claims 1 to 4.

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