JP2000324843A - Power supply and air conditioner provided with that power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce harmonic components of an input current by enlarging the conduction angle of the input current with high efficiency thereby improving power factor. SOLUTION: The power supply comprises a main circuit A comprising a rectifier circuit 2 and a smoothing capacitor 4 for rectifying the voltage of an AC power supply 1 to produce a pulse voltage, and a reactor 3 connected with the input side of the rectifier circuit, and an auxiliary circuit B comprising an auxiliary rectifier circuit 6 connected with the AC power supply and producing a pulse voltage, a plurality of capacitors 8a, 8b connected in series across the output of the auxiliary rectifier circuit, a plurality of switching means 7a, 7b connected in parallel with respective capacitors, and rectifying elements 9a, 9b for preventing backflow of charges from the capacitors to each switching mean when it is tuned on wherein the outputs from the main circuit and the auxiliary circuit are connected electrically and the majority of load current is fed to the main circuit thus reducing loss of the rectifying elements and suppressing the harmonic components in the power supply voltage.

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 an alternating current into a direct current to supply electric power to industrial or consumer electronic equipment, and an air conditioner equipped with the power supply.

[0002]

2. Description of the Related Art Conventionally, as an AC-DC conversion circuit, an AC voltage is input to a diode rectifier circuit to obtain a pulsating voltage.
A capacitor input type rectifier circuit which obtains a DC voltage by smoothing this with a capacitor is used in various fields. And the input current of this rectifier circuit has a narrow current conduction angle, a low power factor, cannot use power effectively because of a large amount of reactive power, and contains many harmonic components and is connected to the same power supply system. Problems with equipment are a problem.

Therefore, a power supply device having a circuit configuration shown in FIG. 4 has been conventionally used as a technique for improving the power factor and reducing harmonic components. In FIG. 4, 101 is an AC power supply, 102 is a reactor for suppressing a sudden change in input current, 103 is a rectifier circuit for obtaining a pulsating voltage from an AC voltage, 1
Reference numeral 04 denotes a capacitor for obtaining a substantially DC voltage by smoothing the pulsating voltage of the rectifier circuit 103, and reference numeral 105 denotes a load connected between the capacitors 104 and supplied with DC power from the power supply device.

In this power supply device, when the AC voltage input from the AC power supply 101 is converted into a pulsating voltage by the rectifier circuit 103, the reactor 102 is inserted, so that the rush of the input current can be reduced. As a result, it is possible to increase the current conduction angle, improve the power factor, and reduce harmonic components contained in the input current. As described above, the power supply device shown in FIG. 4 is used for various devices because the power factor can be improved by providing the reactor, which is a passive component having a simple configuration.

There is also a conventional power supply device having a circuit configuration as shown in FIG. In FIG. 5, an AC power supply 1
And a rectifier circuit 103 for rectifying the rectifier circuit 01.
A reactor 102 connected to the output side of the pulsating voltage of
A plurality of switching means 106a and 106b for turning on and off a current path of an input current;
7a, 107b and these capacitors 107a, 107b
Is charged in the switching means 106a, 106
b, a plurality of rectifiers 108a,
08b, a smoothing capacitor 104 for smoothing the output voltage of the power factor correction circuit to obtain a substantially DC voltage, and a synchronization signal from a zero cross detection circuit 111 for detecting a zero cross of the AC power supply 101. A pulse signal control means 109 for generating and outputting a pulse signal for turning on and off the switching means 106a and 106b of the power factor correction circuit based on the power signal, and a driving circuit 110 for receiving the pulse signal and driving the switching means 106a and 106b. I have it. The pulse signal control means 109 outputs a pulse signal for turning on at least one of the plurality of switching means 106a and 106b for a predetermined period in a half cycle of the AC power supply voltage.

With the configuration shown in FIG. 5, the instantaneous voltage of the AC power supply 101 is lower than the substantially DC voltage of the smoothing capacitor 104, and the switching means 106a and 106b and the capacitors 107a and 107b are used even during the period when the AC power supply 101 does not conduct current. And a rectifying element 108a,
108b through which the current can flow.
1, the current conduction angle is widened, and a high power factor can be obtained.
An inexpensive and simple configuration and control suppress harmonic components to realize a low-loss power supply device.

[0007]

However, in the conventional power supply device shown in FIG. 4, the effect of improving the power factor is so small that a sufficient power factor cannot be obtained. Further, in order to obtain a high power factor with this circuit configuration, it is necessary to increase the value of the reactor 102, which has a problem that the components become large and the power loss associated therewith increases. .

Further, in the conventional power supply device shown in FIG. 5, a high power factor can be obtained by a relatively simple configuration and control, and since the switching frequency in the switching means 106a and 106b is the same as the power supply frequency, the loss is high. Low noise and low harmonic component noise,
It has the advantage of preventing the loss in the noise filter circuit from increasing, but the current is supplied to the load via the rectifier, so the power loss in the rectifier is large,
In addition, there is a problem that a rectifying element having a large rating is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high-efficiency power supply device that prevents an increase in the size of a reactor and an increase in power loss and prevents an increase in power loss due to rectification means.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a rectifier circuit for obtaining a DC voltage from an AC power supply, a smoothing capacitor, a reactor, and a main circuit for supplying power to a load; An auxiliary rectifier circuit that obtains a DC voltage from an AC power supply via a plurality of capacitors connected in series between the outputs of the auxiliary rectifier circuit, a plurality of switching means respectively connected in parallel with the capacitors, and when each of the switching means is in an ON state. An auxiliary circuit including a rectifying element for preventing the electric charge charged in each capacitor from flowing back to each of the switching means,
A power supply device configured to electrically connect an output of the main circuit and an output of the auxiliary circuit.

According to the above configuration, since the auxiliary circuit is not included in the main circuit, the power loss in the rectifying element is greatly reduced,
In addition, power supply harmonic components are also suppressed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 in the power supply device of the present invention is directed to a main circuit for supplying power to a load, comprising a rectifier circuit for obtaining a DC voltage from an AC power supply, a smoothing capacitor, and a reactor; An auxiliary rectifier circuit for obtaining a DC voltage from an AC power supply via a reactor, a plurality of capacitors connected in series between the outputs of the auxiliary rectifier circuit, a plurality of switching means connected in parallel with each of the capacitors and alternately turning on and off, An auxiliary circuit comprising a rectifying element for preventing the electric charge charged in each capacitor from flowing back to each of the switching means when each of the switching means is in an ON state, and an output of the main circuit and an output of the auxiliary circuit are provided. They are electrically connected.

In the above configuration, during a period in which the AC power supply voltage is lower than the rectified pulsating voltage and there is no current conduction, the power supply current is allowed to flow to the auxiliary circuit so that the current conduction angle can be widened and the load can be reduced while suppressing harmonic components. Most of the current is supplied from the main circuit, and no load current flows to the auxiliary circuit.

[0014] The invention described in claim 2 is the first invention.
In the invention according to the description, the voltage drop generated by the rectifier circuit and the smoothing capacitor in the main circuit and the means for connecting them is equal to or less than the voltage drop generated by the auxiliary rectifier circuit, the capacitor and the rectifier in the auxiliary circuit. It is the one that was made.

In the above configuration, more load current flows to the load via the main circuit, resulting in lower loss and a reduction in the current rating of the auxiliary circuit.

[0016] The invention according to claim 3 provides the invention according to claim 1.
In the invention according to the above description, among the auxiliary circuits, at least the auxiliary rectifier circuit, the switching means, and the rectifying element are provided on the same wiring means and integrated.

In the above configuration, an auxiliary circuit is provided independently of the main circuit, and the function of the auxiliary circuit can be added to a power supply device that does not support power supply harmonic current.

The invention described in claim 4 is the first invention.
In the invention according to the description, one of the switching means of the auxiliary circuit is turned on near the zero voltage of the AC power supply, and is turned off when the instantaneous voltage of the AC power supply becomes substantially equal to the load DC voltage, and the zero of the next AC power supply is turned off. In the vicinity of the voltage, the other switching means is turned on in the same manner as described above, and is successively turned off when the instantaneous voltage of the AC power supply becomes substantially equal to the load DC voltage.

In the above configuration, since the current flowing through the reactor does not become discontinuous, sound and vibration from the reactor are greatly reduced. Further, the switching means can be turned on and off only by the relationship between the voltage on the power supply side and the negative voltage of the power supply device, and automatically follows load fluctuations and power supply voltage fluctuations.

According to a fifth aspect of the present invention, there is provided an air conditioner using the power supply device according to any one of the first to fourth aspects, wherein the power supply device is included in the input current at a high power factor. A low-loss air conditioner with suppressed harmonic components.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

Embodiment 1 The invention of Embodiment 1 of the power supply device of the present invention will be described with reference to FIGS. FIG. 1 is a circuit configuration diagram of the power supply device, and FIG. 2 is a waveform diagram of a main part in the circuit configuration. This power supply device includes a main circuit A and an auxiliary circuit B connected to an AC power supply 1. The main circuit A includes a rectifier circuit 2, a reactor 3, and a smoothing capacitor 4. The rectifier circuit 2 is composed of a plurality of rectifier elements 2a, 2b, 2c, and 2d such as diodes, and rectifies an AC voltage to output a pulsating voltage. The reactor 3 is connected between the AC power supply 1 and the rectifier circuit 2 to improve the power factor, and includes a silicon steel sheet core and a wire coil wound around the core. The smoothing capacitor 4 is an electrolytic capacitor for smoothing the pulsating DC voltage of the rectifier circuit 2. 5 is the main circuit A
It is a load such as an inverter device to which more DC power is supplied.

On the other hand, the configuration of the auxiliary circuit B includes an auxiliary rectifier circuit 6, switching means 7a and 7b, capacitors 8a and 8
b, composed of rectifying elements 9a and 9b. The auxiliary rectifier circuit 6 is composed of a plurality of rectifiers 6a, 6b, 6c, 6d such as diodes, and rectifies an AC voltage via the reactor 3 to output a pulsating DC voltage. Switching means 7a,
Reference numeral 7b denotes, for example, a transistor (IGBT or FET), and constitutes an annular circuit with capacitors 8a and 8b, each of which is composed of two small-capacity electrolytic capacitors, and two rectifying elements 9a, 9b each of which includes a rectifying diode. . The midpoint of the series connection of the two switching means 7a and 7b and the midpoint of the series connection of the two capacitors 8a and 8b are connected to each other, and the switching means 7a and the capacitor 8a are connected via the rectifying element 9a. The switching means 7b and the capacitor 8b are connected via a rectifying element 9b. The two switching means 7a and 7b are each driven by amplification by the switch driving means 10 comprising a base driving circuit. The switch driving means 10 detects a zero-cross of the power supply voltage in the AC power supply 1 as a base driving signal, and outputs a signal from the zero-cross detection means 11 for outputting a timing thereof to a pulse signal control means 12 for outputting a pulse width corresponding to a load condition. Output based on The main circuit A and the auxiliary circuit B are connected in parallel to the load 5, and supply power from each.

It should be noted that the pulse signal control means 12 comprises two switching means 7a, 7b in a half cycle of the AC power supply 1.
And generates and outputs a pulse signal (transistor drive signal) for turning on at least one of them for a certain period of time. The pulse signal is composed of a general-purpose logic circuit or a microcomputer and is realized by a one-shot multi-circuit or the like. . The switch driving means 10 receives the pulse signal from the pulse signal control means 12 and drives the switching means 7a and 7b. The switch driving means 10 is configured using a transistor, a dedicated IC, or a photocoupler for electrical insulation. Although a detailed description is omitted, it is composed of a general base drive circuit, a gate drive circuit, a power supply circuit, and the like.

Referring to FIG. 2 which is a timing chart showing a typical control example, FIG. 2A shows a voltage waveform of the AC power supply 1, which is a sinusoidal waveform.
The current waveform in FIG. 4 showing an example of the circuit configuration of the related art becomes discontinuous and becomes a current waveform (b). On the other hand, the zero-cross detecting means 11 outputs the output (c) as a constant pulse signal in synchronization with the zero-cross of the power supply voltage. A control signal is output to the switching means 7a and 7b via the means 10. The output of the switch driving means 10 outputs pulses having a certain width as shown in (d) and (e). By this pulse, each of the switching means 7a and 7b is alternately turned on for a certain period of time, and charging currents (f) and (g) from the AC power supply 1 to the capacitors 8a and 8b via the reactor 3 and the rectifier circuit 6.
Is supplied for each phase of the AC power supply 1. This charging current is a current having a phase that cannot be supplied by the current waveform (b) of the related art. That is, the power supply current from the AC power supply 1 is a power supply current (h) which is the sum of the current waveform (b) and the charging currents (f) and (g). Of course, the load 5 is supplied with DC power, which is mostly rectified by the main circuit A.

Therefore, the phase of the energizing current is expanded, a sufficiently high power factor can be obtained, and harmonic components included in the input current can be suppressed.

The rectifying element 9a is indispensable to prevent the capacitor 8a from being short-circuited when the switching means 7a is turned on, and the same is true for the rectifying element 9b.

Further, according to the configuration of the present invention, since the auxiliary circuit is not included in the main circuit and is independent as in the power supply circuit shown in FIG. 5 showing the prior art, the current flowing through the rectifying elements 9a and 9b is small. , Only the charging current to the capacitors 8a, 8b is obtained, the power loss in the rectifying elements 9a, 9b can be greatly reduced, and the current rating of the rectifying elements 9a, 9b can be reduced. It has the advantages of low cost and miniaturization in terms of cost and size.

As is clear from the first embodiment, according to the power supply device of the present invention, the power supply current is supplied to the auxiliary circuit during the period when the AC power supply voltage is originally lower than the rectified pulsating voltage and there is no current conduction. It is possible to obtain a sufficiently high power factor by widening the conduction angle, and it is possible to provide an inexpensive and simple configuration, and it is possible to supply most of the load current from the main circuit while suppressing harmonic components by control. On the other hand, since a load current does not flow through the auxiliary circuit, it is possible to provide a power supply device capable of reducing the loss and reducing the current rating of the circuit element of the auxiliary circuit.

(Embodiment 2) According to the invention of Embodiment 2, FIG.
Parts having the same configuration and operation and effect as those of the first embodiment are denoted by the same reference numerals, detailed description thereof will be omitted, and different parts will be mainly described.

In FIG. 1, the rectifier circuit 2 in the main circuit A
The voltage drop caused by the load current generated in the auxiliary circuit B, the smoothing capacitor 4 and the wiring and connection means thereof is reduced by the auxiliary rectifier circuit 6 in the auxiliary circuit B, the capacitors 8a and 8b, the rectifier elements 9a and 9b, and the wiring and connection means. The circuit is configured to be equal to or less than the voltage drop caused by the generated load current.

In the above configuration, the main circuit A and the auxiliary circuit B
Is as described in the first embodiment. Then, as the current flowing through the load 5 increases, the difference between the terminal voltage of the smoothing capacitor 4 and the terminal voltages of the capacitors 8a and 8b increases, so that most of the load current naturally flows through the main circuit A, and the rectifying element 9a , 9b can be greatly reduced, and the power loss in the auxiliary rectifier circuit 6 and the capacitors 8a, 8b can also be reduced.

(Embodiment 3) In the invention of Embodiment 3, parts having the same structure and operation and effect as those of Embodiment 1 are denoted by the same reference numerals in FIG. 1 and detailed description thereof will be omitted. explain.

Numeral 14 denotes wiring means for a wiring board having high thermal conductivity (such as an aluminum board or a ceramic copper wiring board).
Circuits a, 6b, 6c, and 6d, switching means 7a and 7b, and rectifying elements 9a and 9b are formed on a substrate by forming a circuit, mounted, and connected to form an integrated module.

In the above configuration, the main circuit A, which cannot be easily realized by the conventional configuration of FIG.
In addition to realizing the independent configuration of the above, it is not only easy to cope with the suppression of the power supply harmonic current, but also the standardization of the circuit and the connection of the circuit in the auxiliary circuit become unnecessary, so that the miniaturization and the cost reduction become possible. In addition, the above-mentioned measures can be easily applied to a power supply apparatus which does not support the suppression of the power supply harmonic current by adding the wiring means of the present invention.

(Embodiment 4) According to the invention of Embodiment 4, parts having the same structure and operation and effect as those of Embodiment 1 are denoted by the same reference numerals in FIG. 3, and detailed description thereof will be omitted. explain.

Reference numeral 13 denotes a voltage comparison circuit, which comprises a comparator for comparing the DC load voltage with the instantaneous voltage of the AC power supply 1, and the like. The voltage comparison circuit 13 replaces the pulse signal control means 12 in the first embodiment. The voltage comparison circuit 13 turns on the switching means 7a of the auxiliary circuit B near the zero voltage of the AC power supply 1, and the instantaneous voltage of the AC power supply 1 A structure in which the switching means 7b is turned on when the voltage is substantially equal to the voltage, the switching means 7b is turned on near the next zero voltage of the AC power supply 1, and the switching means is sequentially turned off when the instantaneous voltage of the AC power supply 1 is substantially equal to the DC load voltage. I have to.

In the above configuration, the main circuit A and the auxiliary circuit B
Is as described in the first embodiment. In addition, since the power supply current supplied from the AC power supply 1 does not become discontinuous, generation of sound and vibration in the reactor 3 can be reduced. Further, when the load increases, the DC load voltage decreases when the load increases, and the switch driving means 1
The width of the drive pulse to 0 is widened, the width of the power supply current is widened, and it naturally functions in the direction of increasing the load voltage. Conversely, when the load is reduced, the DC load voltage increases, the drive pulse width to the switch drive means 10 becomes narrower, the power supply current width becomes narrower, and the load voltage decreases naturally. .

As is apparent from the fourth embodiment, according to the power supply device of the present invention, since the current flowing through the reactor does not become discontinuous, sound and vibration from the reactor can be greatly reduced. Further, since the switching means can be turned on and off only by the relationship between the voltage on the power supply side and the load voltage of the power supply device, it is possible to easily realize a control that automatically follows load fluctuations and power supply voltage fluctuations. .

(Embodiment 5) In the embodiments 1 to 4 of the present invention described above, the power supply device is simply described as the load 5. However, in the embodiment 5 of the present invention, an inverter-driven electric motor is used. Load the inverter device that drives the compressor
It is what it was. Therefore, the present invention can be applied to an air conditioner, and it is possible to provide an air conditioner having a small harmonic component of input current and low power loss.

[0041]

As described above, according to the power supply apparatus of the present invention, a main circuit comprising a rectifying circuit for obtaining a DC voltage from an AC power supply, a smoothing capacitor, and a reactor, and supplying power to a load; An auxiliary rectifier circuit for obtaining a DC voltage from an AC power supply via the reactor, a plurality of capacitors connected in series between outputs of the auxiliary rectifier circuit, and a plurality of switching means connected in parallel with the capacitors and alternately turned on and off, respectively. An auxiliary circuit comprising a rectifying element for preventing electric charges charged in the respective capacitors from flowing back to the respective switching means when each of the switching means is in an ON state, wherein an output of the main circuit and an output of the auxiliary circuit are provided. Are electrically connected to each other, so that a power supply device with low loss and reduced power supply harmonic current can be realized.

According to the second aspect of the present invention, the voltage drop generated by the rectifier circuit in the main circuit, the smoothing capacitor, and the means for connecting these components is reduced by the auxiliary rectifier in the auxiliary circuit. The voltage drop is equal to or less than the voltage drop generated by the circuit, the capacitor, and the rectifying element, and a power supply device with higher efficiency can be provided.

According to the third aspect of the present invention, in the first aspect of the present invention, at least the auxiliary rectifier circuit, the switching means, and the rectifying element are provided on the same wiring means and integrated. This makes it possible to miniaturize and standardize a circuit for suppressing power supply harmonics, and to further improve the loss in connection means.

According to the fourth aspect of the present invention, in the invention according to the first aspect, one of the switching means of the auxiliary circuit is turned on near substantially zero voltage of the AC power supply, and the instantaneous power of the AC power supply is turned on. Turns off when the voltage is substantially equal to the load DC voltage, and turns on the other switching means in the vicinity of the next zero voltage of the AC power supply in the same manner. When the instantaneous voltage of the AC power supply is substantially equal to the load DC voltage, The turning off is sequentially repeated, and a power supply device that follows a load change or a power supply voltage change can be realized by a simple control.

According to a fifth aspect of the present invention, there is provided an air conditioner including an inverter-driven electric compressor using the power supply device according to any one of the first to fourth aspects of the present invention. It is possible to provide an air conditioner that is low in cost and small in size, has a high power factor, has low harmonic components, and has low power loss.

[Brief description of the drawings]

FIG. 1 is a first to a third embodiment of a power supply device according to the present invention;
Circuit configuration diagram showing

FIG. 2 is a waveform diagram of a main part in a circuit configuration of the first to third embodiments of the device.

FIG. 3 is a circuit diagram showing a fourth embodiment of the apparatus.

FIG. 4 is a circuit diagram showing a conventional power supply device.

FIG. 5 is a circuit configuration diagram showing another example of the power supply device.

[Explanation of symbols]

 Reference Signs List A Main circuit B Auxiliary circuit 1 AC power supply 2 Rectifier circuit 3 Reactor 4 Smoothing capacitor 5 Load 6 Auxiliary rectifier circuit 7a, 7b Switching means 8a, 8b Capacitor 9a, 9b Rectifying element 14 Wiring means

Claims (5)

[Claims] 1. A rectifier circuit for obtaining a DC voltage from an AC power supply, a main circuit comprising a smoothing capacitor and a reactor for supplying power to a load, an auxiliary rectifier circuit for obtaining a DC voltage from an AC power supply via the reactor, and this auxiliary rectifier. A plurality of capacitors connected in series between the outputs of the circuit, a plurality of switching means connected in parallel with the capacitors and alternately turned on and off, and the charges charged in the respective capacitors when each of the switching means is in an on state. A power supply device, comprising: an auxiliary circuit including a rectifying element for preventing backflow to each of the switching means, and electrically connecting an output of the main circuit and an output of the auxiliary circuit. 2. A voltage drop generated by a rectifier circuit, a smoothing capacitor, and a means for connecting the rectifier circuit in a main circuit, and a voltage drop generated by an auxiliary rectifier circuit, a capacitor, and a rectifier in an auxiliary circuit are equal to or less than the voltage drop. The power supply device according to claim 1. 3. The power supply device according to claim 1, wherein at least the auxiliary rectifier circuit, the switching means, and the rectifying element of the auxiliary circuit are provided and integrated on the same wiring means. 4. One of the switching means of the auxiliary circuit is turned on near the zero voltage of the AC power supply, and turned off when the instantaneous voltage of the AC power supply becomes substantially equal to the load DC voltage. 2. The power supply device according to claim 1, wherein the other switching means is turned on similarly in the vicinity of the voltage, and is sequentially turned off when the instantaneous voltage of the AC power supply becomes substantially equal to the load DC voltage. 5. An air conditioner comprising the power supply device according to claim 1. Description: