JPH11356051A - Power supply equipment and air conditioner using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply equipment which has an improved power factor and is simple in structure and also provide an air conditioner using the power supply equipment. SOLUTION: This is a power supply equipment which is inputted with power from an AC power supply and then obtains desired DC power. This equipment is constituted of a power factor improving circuit which is forcibly inputted with current from the AC power supply by switching operation of switching elements S1 , S2 and tries to match an input voltage waveform and an input current waveform from the AC power supply, a reference waveform storing section 13 which stores information indicating a reference waveform, an input current detecting circuit 17 for detecting the input current, an output voltage detecting circuit 19 for detecting the output voltage, a zero cross detecting circuit 15 for detecting a point where the polarity of the input (supply) voltage changes, and a controlling section 11 for controlling the power factor improving circuit. The controlling section 11 controls the switching operation of the switching elements S1 , S2 at a duty ratio determined based on an input current value, an output voltage value, and a value of the reference waveform read out from the reference waveform storing setion 13 with the time of detecting the zero cross as a reference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for converting alternating current input from an alternating current power source into direct current and outputting the direct current, and an air conditioner using the same.

[0002]

2. Description of the Related Art Conventionally, a capacitor input type rectifier circuit has been often used as a power supply circuit for home electric appliances and office automation equipment. In this capacitor input type rectifier circuit, a voltage input from an AC power supply is rectified, rectified to DC, and then smoothed by a capacitor to obtain a DC output. However, in the capacitor input type rectifier circuit, the input current does not flow while the input voltage of the AC power supply is lower than the voltage between both ends of the capacitor. The harmonic current affects not only peripheral electric devices used at the same time, but also the power transmission and distribution system. In particular, the effect is remarkable in electric appliances such as air conditioners that consume large power. In view of the above, various power supply devices using a power factor improving circuit for suppressing a harmonic current and improving a power factor have been conventionally devised.

FIG. 6 shows a power supply device using a conventional single-step-up type power factor correction circuit. The power supply device shown in FIG. 6 includes a rectifier circuit D0 for converting alternating current to direct current, a power factor improving unit 9 for increasing a power factor, and a smoothing capacitor C for smoothing rectified direct current. It has an input voltage detection circuit 7 for detecting Vi, an input current detection circuit 17 for detecting the input current I, and an output voltage detection circuit 19 for detecting the output voltage Vo. In the power supply device having such a configuration, the AC input from the AC power supply AC is converted into DC by the rectifier circuit D0, and then the voltage smoothed by the smoothing capacitor C is obtained as the output voltage Vo.

As described above, when the voltage of the input voltage Vi is lower than the voltage of the capacitor C, the input current I does not flow, but during this period, the power factor improving section 9 intermittently switches the switching element S. By opening and closing, the input current I is forced to flow, thereby changing the waveform of the input current I to the input voltage Vi.
Close to the waveform of That is, when the switching element S is on, energy is stored in the reactor L, and when the switching element S is off, the input current I is forced to flow through the diode D7 by the stored energy. The switching element S is subjected to PWM control based on a control signal from the control unit 11a.

[0005] The control unit 11a includes a detection circuit 7
The duty ratio of the switching element S is determined by multiplying the input voltage Vi, the input current I, and the output voltage Vo input from the switches 17 and 19 in an analog manner. At this time, the power factor is improved by determining the duty ratio so that the waveform of the input current I approaches the waveform of the input voltage Vi, and the harmonic current is suppressed.

[0006]

However, the above-described power supply device is generally connected to the commercial power supply AC via a noise filter or the like in order to prevent an influence on the connected commercial power supply AC. At this time, the input voltage waveform may be distorted by the influence of the noise filter or the like. In the conventional power supply device that determines the duty ratio based on the input voltage waveform, when the input voltage waveform is distorted, there is a problem that the duty ratio is not properly obtained and the power factor is not sufficiently improved.

When the control unit 11a is formed of a general semiconductor integrated circuit for digital signal processing in order to reduce the size and cost of the device, the detection signals of the input voltage, input current and output voltage are used. It is necessary to have an AD converter for analog-to-digital conversion inside each. However, since a circuit for realizing the AD converter is complicated, the provision of the AD converter for each of the input voltage, the output voltage, and the input current increases the size and cost of the semiconductor integrated circuit, and also increases the processing speed. There is also a problem that it becomes slow.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to improve a power factor improvement efficiency and realize a power supply device which can be realized with a simple configuration and an air conditioner using the same. Offer machine.

[0009]

According to a first aspect of the present invention, there is provided a power supply apparatus for converting an AC input from an AC power supply into a DC power and outputting the DC power, the reference power supply storing information indicating a predetermined reference waveform. Storage means; and power factor improving means for bringing the waveform of the input current from the AC power supply closer to the reference waveform indicated by the information stored in the reference waveform storage means.

A second power supply device according to the present invention is a power supply device for rectifying an AC voltage input from an AC power supply into a DC voltage, and smoothing the rectified DC voltage to obtain a DC output voltage. The power supply device includes a switching element and a reactor, and forcibly draws an input current from an AC power supply via the reactor by opening and closing the switching element, so that a waveform of the input current approaches a power supply voltage waveform. Rate improvement means, reference waveform storage means for storing information indicating a predetermined reference waveform, input current detection means for detecting an input current from an AC power supply, output voltage detection means for detecting an output voltage, The control device includes a zero-cross detecting unit that detects a zero-cross point at which the polarity changes, and a control unit that controls an opening and closing operation of the switching element.
At this time, the control means includes a reference waveform storage means based on the input current value detected by the input current detection means, the output voltage value detected by the output voltage detection means, and the timing at which the zero cross is detected by the zero cross detection means. The switching timing of the switching element of the power factor improving means is determined on the basis of the value of the reference waveform read out from the CPU, and the switching operation of the switching element is controlled using the timing.

An air conditioner according to the present invention has an electric compressor for compressing a refrigerant for heating or cooling air used for temperature control. Further, the air conditioner further includes the above power supply device and an output voltage from the power supply device. Conversion means for converting into a desired AC voltage, and the electric compressor is driven by an output voltage from the conversion means.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a power supply device according to an embodiment of the present invention. The power supply device of the present embodiment is a power supply device including a power factor improvement circuit that improves a power factor by forcibly flowing a current through a reactor by performing a switching operation of a switching element. A reference waveform storage unit that stores information indicating a reference waveform to be a control target when controlling the current; The power supply device controls the switching operation of the switching element based on the reference waveform stored in the reference waveform storage unit such that the waveform of the input current becomes equal to the reference waveform. This eliminates the need to detect the input voltage,
The power factor can be improved independently of the input voltage waveform.

<Structure of Power Supply> FIG. 1 is a circuit diagram of the power supply according to the present embodiment. The power supply device includes diodes D1 to D4 for rectifying power input from the AC power supply AC.
And a reactor L and switching elements S1 and S2 for forcing an input current Iin to flow from an AC power supply AC by a switching operation, and a smoothing capacitor C for obtaining a smoothed DC output. Includes boost type power factor correction circuit. Further, the power supply device includes a control unit 11 that controls opening and closing of the switching elements S1 and S2 of the power factor improvement circuit, a reference waveform storage unit 13 that stores a reference waveform that is a control target of the waveform of the input current Iin, Power supply AC
A zero-crossing detection circuit 15 for detecting a zero-crossing point at which the polarity of the input current changes, an input current detection circuit 17 for detecting an input current Iin, and an output voltage detection circuit 19 for detecting an output voltage Vout.

The control unit 11 includes switching elements S1, S
Duty ratio determining unit 21 that determines a duty ratio when PWM control is performed on PWM 2 and switching element S based on the duty ratio determined by duty ratio determining unit 21.
1. P that outputs a control signal for controlling the opening and closing of S2
And a WM control unit 23. The control unit 11 receives respective detection signals from the zero-cross detection circuit 15, the input current detection circuit 17, and the output power detection circuit 19.
Here, the control unit 11 is configured by a semiconductor integrated circuit that processes digital signals.

The reference waveform storage section 13 stores data indicating a reference waveform which is a control target of the input current waveform. The reference waveform storage unit 13 normally stores a power supply voltage waveform, that is, a sine wave waveform as a reference waveform in order to increase the power factor. For example, as shown in FIG. 2A, the time and the peak value of the normalized sine wave at that time are stored as a table in association with each other. The data shown in FIG.
This represents a sine wave waveform as shown in FIG. The reference waveform storage unit 13 may be included in the control unit 11.

FIG. 3A shows an example of the configuration of the zero-cross detection circuit 15. As shown in FIG. 3A, the zero-cross detecting circuit 15 includes resistors 31 and 33 and a comparator 35.
It is composed of The zero-cross detection circuit 15 connects the reference potential of the AC power supply AC and the output voltage of the AC power supply AC with a resistor 3
The potential obtained by dividing the voltage at 1, 33 and the comparator 35
, A time point (zero cross) at which the polarity of the voltage of the AC power supply AC changes is detected. FIG. 3 (b)
Indicates a voltage waveform of the AC power supply AC, that is, an input of the zero-cross detection circuit 15. FIG. 3C shows the output of the zero-cross detection circuit 15 with respect to the input of FIG.
This is referred to as a “zero cross detection signal”. ). As shown in the figure, the detection of the zero cross can be recognized by the rising or falling of the zero cross detection signal. like this,
Detection of a rising or falling edge of a signal can be generally realized by a simple circuit configuration in a digital processing circuit.

<Operation of Power Supply Device> In the power supply device configured as described above, an AC voltage input from an AC power supply AC is rectified by diodes D1 to D4, and a smoothing capacitor C
The DC voltage obtained by smoothing is defined as the output voltage Vout. The output voltage Vout is applied to the load LD. On the other hand, the input current Iin from the AC power supply AC is
1 and S2, the reference waveform storage unit 1
3 is controlled so as to have the waveform of the reference waveform stored.

That is, when the switching elements S1 and S2 are opened and closed intermittently, the energy is accumulated or released in the reactor L accordingly, and the input current Iin is forcibly drawn from the AC power supply AC, whereby the input The waveform of the current Iin is made closer to the reference waveform. Specifically, the waveform of the input current Iin matches the reference waveform by appropriately controlling the opening / closing timing of the swing elements S1 and S2, that is, the duty ratio.

FIG. 4A shows the waveforms of the input voltage (voltage of the AC power supply AC) Vin, the input current Iin, and the output voltage Vout in the power supply device, and FIGS. 4B and 4C show the switching elements S1, The waveforms of control signals for controlling the opening and closing of S2 are shown. In the present embodiment, FIG.
By performing a switching operation over the entire power supply frequency range as shown in FIG. 3C, the input current waveform is synchronized with the reference waveform (or the power supply voltage waveform). At this time, the switching operation may be partially performed only during the period when the input voltage Vin is lower than the voltage across the smoothing capacitor C. Further, as shown in FIGS. 4B and 4C, only one of the switching elements S1 and S2 selectively performs a switching operation according to the polarity of the power supply voltage. The selection of the switching element at this time will be described later.

Hereinafter, P of the switching elements S1 and S2 will be described.
The determination of the duty ratio in the WM control will be described. The duty ratio of the switching elements S1 and S2 (FIG. 4
In (c), Ton / T) is determined by the duty ratio determination unit 21 in the control unit 11. The duty ratio determination unit 21 includes an input current value Iin detected by the input current detection circuit 17, an output voltage value Vout detected by the output voltage detection circuit 19, and a waveform of the reference waveform stored in the reference waveform storage unit 13. The duty ratio is determined based on the high value.

In this case, the duty ratio determining unit 21 uses the timing at which the zero-cross detection circuit 15 detects the zero-cross of the input voltage as a reference, and
Read the peak value of the reference waveform from. For example, when the rising edge of the zero-crossing detection signal is detected (when the zero-crossing of the power supply voltage from negative to positive is detected), the time is synchronized with the rising edge of the waveform (time 0 in FIG. 2), and The peak value of the reference waveform is read from the reference waveform storage unit 13 in accordance with the elapsed time of. When a falling edge of the zero-crossing detection signal is detected (when a zero-crossing of the power supply voltage from positive to negative is detected), the time is synchronized with the falling edge of the waveform (time tm in FIG. 2). Read the peak value of the reference waveform. As described above, in the power supply device of the present embodiment, when reading the peak value of the reference waveform from the reference waveform storage unit 13, the peak value is read based on the zero-cross timing detected by the zero-cross detection circuit 15.

The duty ratio determination unit 21 calculates the peak value Vs of the reference waveform read from the reference waveform storage unit 13 as described above, the input current value Iin detected by the input current detection circuit 17, and the output voltage detection circuit. The duty ratio Dt is determined based on the output voltage value Vout detected by the step S19. That is, the following relationship is established. Dt = f (Iin, Vout, Vs) (1) where f (x) represents a function based on x.

In the control unit 11, a PWM control unit 23
Outputs a control signal to the switching elements S1 and S2 in order to perform PWM control on the switching elements S1 and S2 at the duty ratio Dt obtained by the duty ratio determination unit 21 as described above. At this time, the PWM control unit 23
Is based on a detection signal from the zero-cross detection circuit 15,
A switching element for performing a switching operation at the duty ratio determined by the duty ratio determination unit 21 is selected. That is, as shown in FIG. 4, the PWM control unit 23 operates the switching element S1 when the power supply voltage is positive, that is, during a period from the detection of the rising edge of the zero-cross detection signal to the detection of the falling edge. A control signal is output so that the switching element S2 is always closed. On the contrary, when the power supply voltage is negative, that is, during a period from when the falling edge of the zero-cross detection signal is detected to when the rising edge is detected. Outputs a control signal to operate the switching element S2 (while the switching element S1 is always closed).

Here, in the present embodiment, the reference waveform stored in the reference waveform storage unit 13 is not limited to a sine wave, but may be a reference waveform corresponding to various load conditions and the like. . For example, a waveform corresponding to a periodic load change may be stored. This makes it possible to appropriately improve the power factor according to the load situation. As described above, in the present embodiment, the waveform of the input voltage used as a reference in the control for improving the power factor can be adjusted according to the load condition. Thus, even when there is a periodic load change, a properly high power factor can be obtained. Further, the duty ratio determination unit 21 reads the reference waveform of the input voltage from the reference waveform storage unit 13 instead of the zero-cross detection circuit 1.
The value of the sine wave may be calculated internally using the timing at which the zero cross is detected in step 5 as a trigger, and the duty ratio may be obtained using this value. Even in such a method, the power factor can be improved without detecting the input voltage.

Further, in this embodiment, an example in which the present invention is applied to a two-step booster type power factor improving circuit has been described. The present invention can be similarly applied to a power factor improving circuit of a type or a buck-boost type. That is, for these power factor improvement circuits, the reference waveform of the input voltage is stored, and instead of detecting the input voltage in the control of the power factor improvement, the stored reference waveform value is used instead of the stored reference waveform. By controlling the opening and closing of the switching element in the same manner as in the embodiment, the same effect as in the above-described embodiment can be obtained.

As described above, in the power supply device according to the present embodiment, the reference waveform is stored in the reference waveform storage unit 13 in advance, and the switching element is controlled so that the waveform of the input current Iin matches the stored reference waveform. A duty ratio for PWM control of S1 and S2 is obtained. Thereby, the power supply device of the present embodiment does not need to detect the input voltage,
The power factor can be improved independently of the actual input voltage waveform, and the power factor can be appropriately improved even when the input voltage is distorted. Further, since a circuit for detecting an input voltage is not required, when the control unit 11 for controlling the power supply device is configured by a semiconductor integrated circuit for digital signal processing, an AD converter for reading an input voltage waveform is provided. Since it is not required, the circuit configuration of the semiconductor integrated circuit is simplified, and downsizing and cost reduction can be achieved. Also, since it is possible to store a waveform generated according to the situation as a reference waveform,
The control of the duty ratio can be changed according to the operation situation, and for example, the power factor improvement control corresponding to a periodic load change or the like can be performed.

<Structure and Operation of Air Conditioner> FIG. 5 is a schematic block diagram showing a structure of an air conditioner using the power supply device of the present embodiment. As shown in FIG. 5, the air conditioner includes an electric compressor 31, an outdoor heat exchanger 33, an expansion valve 35,
A refrigeration cycle including an indoor heat exchanger 37 and a four-way valve 39 is provided. Blowers 33a, 37a are provided for the heat exchangers 33, 37, respectively. During the refrigeration cycle, a refrigerant as a heat medium circulates. The refrigerant is the electric compressor 3
And compressed by the outdoor heat exchanger 33 to blower 33a
The heat is exchanged with the outdoor air by the air blown from the inside, and the heat is exchanged with the indoor air by the air blown by the blower 37a in the indoor heat exchanger 37. The indoor air is cooled and heated by the air after the heat exchange in the indoor heat exchanger 37. Switching between cooling and heating is performed by reversing the circulation direction of the refrigerant by the four-way valve 39.

The air conditioner includes, in addition to the refrigeration cycle described above, a power supply A, a DC / AC conversion circuit 41 for converting a DC voltage from the power supply A into a three-phase AC, and an operation performed by a user. And a panel 43. The DC / AC conversion circuit 41 includes a plurality of switching elements, and converts the DC voltage output from the power supply device A into an AC voltage of a desired power by controlling the switching of the switching elements. The converted AC voltage is supplied to the electric compressor 3
1 is supplied as drive power. The configuration and operation of the power supply device A are the same as those described above, and a description thereof will be omitted. In the air conditioner, the power supply device A includes an electric compressor, a blower 33a for the heat exchangers 33 and 37,
Electric power is supplied as a power supply for operating 37a and the like.

As described above, in the air conditioner, the power factor of the input current is improved and the generation of the harmonic current is suppressed by using the power supply device A of the present embodiment as the power source. An air conditioner that does not adversely affect the system and the like can be realized.

[0030]

According to the power supply apparatus of the present invention, there is provided a waveform storage means for storing information on the input voltage waveform, and control for improving the power factor is performed based on the reference waveform stored in the waveform storage means. . Therefore, the power factor can be improved without depending on the actual input voltage waveform, and the appropriate power factor can be improved even when the input voltage waveform is distorted. Further, since it is not necessary to detect the input voltage, when the control means for controlling the power supply device is constituted by a semiconductor integrated circuit for digital signal processing, an AD converter for taking in the input voltage is not required. The circuit configuration of the semiconductor integrated circuit becomes simpler, and downsizing and cost reduction can be realized. Furthermore, by storing a reference waveform corresponding to a periodic load change or the like in the waveform storage means, it is possible to appropriately improve the power factor even when there is a load change or the like.

According to the air conditioner of the present invention, since the electric compressor is driven by using the power supply device as a power source, the power factor of the input current is improved and the generation of harmonic current is suppressed. An air conditioner that does not adversely affect the distribution system or the like can be realized.

[Brief description of the drawings]

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

2A is a diagram illustrating reference waveform data stored in a reference waveform storage unit, and FIG. 2B is a diagram illustrating a reference waveform indicated by the reference waveform data in FIG.

3A is a circuit diagram illustrating an example of a zero-cross detection circuit, FIG. 3B is a diagram illustrating an input voltage waveform to the zero-cross detection circuit, and FIG. 3C is a diagram illustrating a waveform of an output signal of the zero-cross detection circuit.

4A is a diagram showing waveforms of an input (power) voltage, an input voltage, and an output voltage of a power supply device, FIG. 4B is a diagram showing a waveform of a control signal for controlling opening and closing of the switching element S1, and FIG. The figure which shows the waveform of the control signal which controls opening / closing of the switching element S2.

FIG. 5 is a configuration block diagram of an air conditioner according to the present invention.

FIG. 6 is a circuit diagram showing a configuration of a conventional power supply device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 control unit 13 reference waveform storage unit 15 zero-cross detection circuit 17 input current detection circuit 19 output voltage detection circuit 21 duty ratio determination unit 23 PWM control unit 31 electric compressor 41 DC / AC conversion circuit A power supply device AC commercial power supply C smoothing capacitor S1 , S2 switching element.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Okui 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A power supply device for converting alternating current input from an alternating current power supply to direct current and outputting the converted direct current, wherein reference waveform storage means for storing information indicating a predetermined reference waveform; A power supply device comprising: a power factor improving unit configured to approach a reference waveform indicated by information stored in the reference waveform storage unit. 2. A power supply apparatus for rectifying an AC voltage input from an AC power supply into a DC voltage and smoothing the rectified DC voltage to obtain a DC output voltage, comprising: a switching element and a reactor; Power factor improving means for forcibly extracting an input current from the AC power supply via the reactor by opening / closing an element to bring the input current waveform closer to the power supply voltage waveform; and a predetermined reference waveform. Reference waveform storage means for storing information indicating the following; input current detection means for detecting an input current from the AC power supply; output voltage detection means for detecting the output voltage; and when the polarity of the input voltage changes. Zero cross detection means for detecting a certain zero cross, an input current value detected by the input current detection means,
An output voltage value detected by the output voltage detection means,
Based on the timing at which the zero-crossing is detected by the zero-crossing detecting means and the value of the reference waveform read from the reference waveform storing means, the timing of opening and closing the switching element of the power factor improving means is determined. And a control unit for controlling the opening and closing operation of the switching element by using the power supply device. 3. An air conditioner comprising an electric compressor for compressing a refrigerant for heating or cooling air used for temperature control, wherein the power supply device according to claim 1 or 2 and the power supply device Converting means for converting the output voltage of the air conditioner into a desired AC voltage, and driving the electric compressor with the output voltage from the converting means.