JPH1052048A - Power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the power factor of a power unit, by connecting in parallel a serial circuit of a first reactor and a diode to a capacitor in parallel with each other in one side between the AC and DC side of a rectifier circuit, and connecting a second reactor to the AC input side of the rectifier circuit. SOLUTION: An electric current IL1 flowing to a first reactor 5 produces a firing angle expanding effect when the current falls (on the lagging side) due to the inertial current effect of a reactor. In addition, the resonant state (frequency and level) of a serial resonant current IC1 of a capacitor 7 and the inductance component Ls of a power system can be adjusted freely by means of a second reactor 2 connected between the capacitor 7 and the inductance component Ls of the power system. A filter capacitor 4 is connected in series with the charging route of the capacitor 7, but the resultant capacitance of the serial circuit of the capacitors 4 and 7 becomes nearly equal to the capacitance of the capacitor 7, because the capacitance of the capacitor 4 is sufficiently larger as compared with that of the capacitor 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power supply device,
More specifically, the present invention relates to a power supply device for achieving an improvement in power factor and suppression of intermediate-order harmonic current.

[0002]

2. Description of the Related Art With the use of inverters in air conditioners, lighting equipment, and the like, rectifier loads, which generate a large amount of harmonics, are rapidly increasing in comparison with conventional AC loads. For this reason, voltage distortion occurs in the power system, and problems such as beats and ignition of phase-advancing capacitors and transformers have occurred. In addition, in consideration of such a problem, a home appliance / general product harmonic guideline has been set. Of course, these guidelines also apply to air conditioners. With these guidelines in mind,
2. Description of the Related Art Conventionally, a power supply device for improving a power factor and reducing a harmonic has been proposed.

The power supply device shown in FIG. 10 has a reactor 15 connected between a full-wave rectifier circuit 13 for full-wave rectification of an input voltage and a smoothing capacitor 14. If this power supply device is adopted, as shown in the waveform diagram of FIG. 11, the conduction angle of the input current is enlarged by the reactor 15 inserted immediately after the full-wave rectifier circuit 13, and the current peak is reduced. Wave reduction and power factor improvement can be achieved. However, this power supply device has only a conduction angle enlargement effect at the time of current falling (slower side), and thus has a low power factor improvement effect. 11A shows an input voltage waveform, FIG. 11B shows an output voltage waveform of a full-wave rectifier circuit, and FIG.
Represents the voltage waveform between the terminals of the smoothing capacitor, and the input current waveform (D) in FIG.

FIG. 12 is an electric circuit diagram of a conventional power supply for further improving the power factor. The difference from the power supply of FIG. 10 is that a diode 16 is connected in series with the reactor 15 and And diode 16
(See Japanese Patent Application Laid-Open No. 1-248966). If this power supply device is adopted, as shown in the waveform diagram of FIG.
In addition to the improvement effect of the power supply device of FIG.
, The conduction angle can be increased when the current rises (leading side) due to the charge / discharge current. The charging current of the capacitor 17 rises earlier than the current of the reactor 15, and FIG.
The power supply device can achieve a larger conduction angle.
Further, the current of the capacitor 17 can suppress the peak of the current of the reactor 15. Therefore, low-order harmonics can be suppressed and the input power factor can be improved.
13 (A) is the input voltage waveform, and FIG. 13 (B)
13 is an output voltage waveform of the full-wave rectifier circuit, (C) in FIG. 13 is a voltage waveform between terminals of the smoothing capacitor, (D) is an input current waveform in FIG. 13, (E) is a current waveform flowing through the reactor,
(F) in FIG. 13 shows the waveform of the current flowing through the capacitor.

[0005]

When the power supply shown in FIG. 12 is employed, a high power factor can be achieved.
The capacitor forms a series resonance circuit with the inductance component of the power supply system, and the capacitance of the capacitor at the power factor optimum point changes the resonance frequency of the series resonance circuit by 10 to 30 times the power supply frequency.
In order to double, 10 th to 30 th harmonic currents protrude,
The power supply device does not conform to the above-mentioned harmonic guidelines.

FIG. 14 shows a harmonic guideline for home appliances and general-purpose products, and an input current harmonic distribution when a 1.2 kW load is connected to the power supply device of FIG. As is apparent from this figure, when the power supply device shown in FIG. 12 is employed, a specific harmonic component having an intermediate order (10 to 30) is prominent. This protrusion is caused by the capacitor C1 for power factor improvement.
This occurs because the power supply system and the inductance component Ls of the power supply system form a series resonance circuit. Here, the standard value of the inductance component Ls of the power supply system is determined by a guideline for harmonics of home electric appliances and general-purpose products.
The inductance component of the V power supply system is 0.46 mH. Further, the capacitor C1 needs a capacitance of about several tens to 100 μF in order to have a power factor improving effect, and the resonance frequency with the power supply system inductance at this time becomes 10 to 30 times the power supply frequency. The aforementioned intermediate order harmonic protrusion occurs.

[0007] Since the inductance of the power supply system is invariable, it is necessary to adjust the capacitance of the capacitor C1 in order to change the resonance frequency. The power factor improvement effect disappears, resulting in a power supply device with poor power factor performance.
Therefore, it is impossible to achieve both improvement of the power factor and suppression of intermediate-order harmonics.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a power supply device which can improve the power factor and which complies with the guidelines for harmonics for home appliances and general-purpose products.

[0009]

According to a first aspect of the present invention, there is provided a power supply device comprising:
A power supply device for rectifying an AC input voltage by a rectifier circuit and applying a DC voltage to a rectifier load, wherein a series connection circuit of a first reactor and a diode is provided on one of an AC side and a DC side of the rectifier circuit. And a capacitor are connected in parallel with each other, and a second reactor is connected to the AC input terminal.

According to a second aspect of the present invention, there is provided a power supply device wherein a series connection circuit of a first reactor and a diode and a capacitor are connected in parallel between an output terminal of the rectifier circuit and a positive terminal of a smoothing capacitor. is there. The power supply device according to claim 3, wherein a series connection circuit of a first reactor and a diode is connected between an output terminal of the rectifier circuit and a positive terminal of the smoothing capacitor, and the first reactor, the diode and the smoothing capacitor are connected in series. A capacitor is connected in parallel with the connection circuit.

According to a fourth aspect of the present invention, a three-phase rectifier circuit is employed as the rectifier circuit, and a first reactor is connected between one AC input terminal and a first phase of the three-phase rectifier circuit. 1
A capacitor is connected to the second phase of the three-phase rectifier circuit in parallel with the reactor described above, and the other AC input terminal is connected to the third phase of the three-phase rectifier circuit. The power supply device according to claim 5 employs, as the second reactor, a device externally connected to an input terminal of the rectifier circuit.

According to a sixth aspect of the present invention, as the second reactor, a second reactor connected to a power supply system side of a power supply device inside a load device to which an AC voltage is supplied by a power supply system is employed.

[0013]

According to the power supply device of the present invention, an AC input voltage is rectified by a rectifier circuit to apply a DC voltage to a rectifier load, and one of an AC side and a DC side of the rectifier circuit. In addition, a series connection circuit of a first reactor and a diode and a capacitor are connected in parallel to each other, and a second reactor is connected to an AC input terminal. By connecting the two reactors in series, the resonance frequency and the level of the resonance current are adjusted, whereby the resonance current can be reduced and the power factor can be improved by increasing the charging effect of the capacitor. .

According to a second aspect of the present invention, a series connection circuit of a first reactor and a diode and a capacitor are connected in parallel between an output terminal of the rectifier circuit and a positive terminal of a smoothing capacitor. Therefore, the same operation as the first aspect can be achieved. The power supply device according to claim 3, wherein a series connection circuit of a first reactor and a diode is connected between an output terminal of the rectifier circuit and a positive terminal of the smoothing capacitor, and the first reactor, the diode and the smoothing capacitor are connected. Since the capacitor is connected in parallel with the series connection circuit of the above, the same operation as the first aspect can be achieved.

According to a fourth aspect of the present invention, a three-phase rectifier circuit is employed as the rectifier circuit, and a first reactor is connected between one AC input terminal and a first phase of the three-phase rectifier circuit. Since the capacitor is connected to the second phase of the three-phase rectifier circuit in parallel with the first reactor and the other AC input terminal is connected to the third phase of the three-phase rectifier circuit, Can be achieved.

According to the power supply device of the present invention, since the second reactor is externally connected to the input terminal of the rectifier circuit, it can be easily applied to an existing power supply device. It is possible to achieve an effect of reducing intermediate order harmonics. The power supply device of claim 6 is
As the second reactor, the one connected to the power supply system side of the power supply device inside the load device to which the AC voltage is supplied by the power supply system is employed, so that it is easily connected to the existing power supply device. And an effect of reducing intermediate order harmonics can be achieved.

[0017]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an electric circuit diagram showing one embodiment of the power supply device of the present invention. In this power supply device, a full-wave rectifier circuit 3 is connected between both terminals of an input power supply 1 via a second reactor 2. Then, between the smoothing capacitor 4 for applying a voltage to the load and the full-wave rectifier circuit 3, the first reactor 5 and the forward-connected diode 6 connected in series with each other, and the capacitor 7 are connected in parallel with each other. Have been.

FIG. 2 is a diagram showing waveforms at various parts of the power supply device of FIG. 2A shows an input voltage waveform, FIG. 2B shows a voltage waveform at an output terminal of the second reactor 2,
2C is the output voltage waveform of the full-wave rectifier circuit 3, FIG. 2D is the voltage between the terminals of the smoothing capacitor 4, and FIG.
2 shows an input current waveform, FIG. 2 (F) shows a current waveform flowing through the first reactor 5, and FIG. 2 (G) shows a current waveform flowing through the capacitor 7, respectively.

Therefore, when this embodiment is adopted, the current IL1 flowing through the first reactor 5 has an effect of increasing the conduction angle at the time of the current falling (slower side) due to the inertial current effect of the reactor. In addition, the series resonance current IC1 of the capacitor 7 and the inductance component Ls of the power supply system, which is hardly adjustable in the conventional power supply device, is connected to the second resonance current IC1 inserted between the capacitor 7 and the inductance component Ls of the power supply system. The state of resonance (frequency,
Level) can be adjusted freely. The smoothing capacitor 4 is connected in series to the charging path of the capacitor 7, but since the capacity of the smoothing capacitor 4 is sufficiently larger than the capacity of the capacitor 7, a series connection circuit of the capacitor 7 and the smoothing capacitor 4 is provided. Is substantially equal to the capacitance of the capacitor 7.

By setting this resonance frequency to about 3 to 7 times the power supply frequency, the conduction period of the capacitor 7 (FIG. 2)
(T1 to t5), charging / discharging is almost completed once (the current of the capacitor 7 approximates one cycle of a sine wave).
The charging current of the capacitor 7 (t1 to t3 in FIG. 2) has a power factor improving effect by enlarging the conduction angle when the current rises (leading side), and the discharging current of the capacitor 7 (t3 to t4 in FIG. 2) suppresses the current peak. Has a low-order harmonic reduction effect and a power factor improvement effect. The period from t4 to t5 in FIG. 2 is a residual current due to the inertial current effect of the first reactor 5, and this current also has a slight effect of increasing the conduction angle.

In this embodiment, the capacitor 7 current I
C1 does not cause high-frequency resonance unlike the conventional power supply shown in FIG. 12 due to the insertion of the second reactor 2,
Does not result in an increase in intermediate order harmonics (see harmonic distribution shown in FIG. 3). Thus, according to this embodiment,
A high-performance power supply with a high power factor and low harmonics (conforms to the guidelines for harmonics for home appliances and general-purpose products) can be realized.

Further, the effective value of the charge / discharge current of the capacitor 7 in this embodiment increases due to the pump effect of the second reactor 2. That is, as compared with the capacitor used in the power supply device of FIG. 12, the effect of increasing the conduction angle on the leading side and the power factor improvement performance due to the effect of suppressing the current peak of the first reactor 5 are further improved. The input power factor of the device is even higher than that of the power supply device of FIG.

FIG. 4 is an electric circuit diagram showing another embodiment of the power supply device of the present invention. This embodiment differs from the power supply device of FIG. 1 in that the first reactor 5 and the diode 6
The only difference is that the capacitor 7 is connected in parallel with the series connection circuit of the first reactor 5, the diode 6, and the smoothing capacitor 4 instead of connecting the capacitor 7 in parallel with the series connection circuit. The capacity of the smoothing capacitor 4 is shown in FIG.
2, the capacitance is sufficiently larger than the capacitance of the capacitor 7.

In this power supply, a path for charging the smoothing capacitor 4 through the first reactor 5 is the same as that of the power supply in FIG. The charging / discharging path of the capacitor 7 is different from that of the power supply circuit of FIG. 1, and the state of resonance is determined by the capacitance of the reactor 2 and the capacitor 7 for charging, and the reactor 5, the capacitor 7 and the capacitor 7 for discharging. The state of resonance is determined by the smoothing capacitor 4 which is connected in series to the circuit. However, as described above, since the capacity of the smoothing capacitor 4 is sufficiently larger than the capacity of the capacitor 7, the combined capacity of the series connection circuit of the capacitor 7 and the smoothing capacitor 4 is almost equal to the electrostatic capacity of the capacitor 7. Become equal.

Therefore, even when the capacitor 7 is connected in this manner, the power factor improving effect and the intermediate order harmonic reducing effect can be achieved in the same manner as in the power supply device of FIG. FIG. 5 is an electric circuit diagram showing still another embodiment of the power supply device of the present invention.
In this power supply device, instead of providing a closed circuit including the first reactor 5, the capacitor 7, and the diode 6 on the output side of the full-wave rectifier circuit 3, it is provided on the input side of the full-wave rectifier circuit 3.

More specifically, a three-phase full-wave rectifier circuit is adopted as the full-wave rectifier circuit 3, and the second terminal is connected to one terminal of the input power supply 1.
, And the first reactor 5 is connected between the second reactor 2 and the first phase of the full-wave rectifier circuit 3 (see A in FIG. 5). The capacitor 7 is connected between the second reactor 2 and the second phase of the full-wave rectifier circuit 3, and the other terminal of the input power supply 1 is connected to the third phase of the full-wave rectifier circuit 3. Further, a smoothing capacitor 4 is connected between output terminals of the full-wave rectifier circuit 3.

The first phase of the full-wave rectifier circuit is shown in FIGS.
In this embodiment, a reverse current is blocked similarly to the diode 6 in this embodiment. However, in this embodiment, a reverse current blocking effect can be exhibited for an AC bidirectional current. FIG. 6 is a diagram showing waveforms at various parts of the power supply device of FIG. FIG.
6 (A) is the input voltage waveform, FIG. 6 (B) is the voltage waveform at the output end of the second reactor 2, FIG. 6 (C) is the voltage between the terminals of the smoothing capacitor 4, and FIG. FIG. 6E shows an input current waveform, FIG. 6E shows a current waveform flowing through the first reactor 5, and FIG. 6F shows a current waveform flowing through the capacitor 7.

Next, the operation of the power supply device of FIG. 5 will be described with reference to the waveforms of FIG. The first reactor 5 has the effect of increasing the conduction angle when the current falls (slower side) as in the case of the power supply devices of FIGS. 1 and 4 (see FIG. 6F). On the other hand, since the reverse current of the capacitor 7 is blocked by the first-phase diode of the full-wave rectifier circuit 3, no discharge is performed within a half cycle. Then, the capacitor 7 discharges the charge current in the next half cycle, that is, the capacitor 7 in the negative half cycle.
This is done by the reverse current flowing through. This reverse charging current simultaneously increases the conduction angle when the current rises (leading side) in the next half cycle (negative half cycle) (see (E) in FIG. 6). Also, the second reactor 2 inserted in the AC input terminal
Has a pumping effect on the charging current of the capacitor 7, and FIG.
A power factor improving effect similar to that of the second reactor of the power supply device of FIG. 3 is exhibited.

The resonance frequency and the level of the resonance current of the series resonance circuit (the power supply system inductance component, the capacitor 7, the second reactor 2, and the smoothing capacitor 4) including the power supply system inductance component Ls are provided by the second reactor 2. Can be adjusted, and suppression of intermediate order harmonics can be achieved (see the harmonic distribution in FIG. 7).

As a result, a power supply circuit with high efficiency and low harmonic current can be realized. According to the power supply device of the present invention, an AC reactor (second reactor 2) is added to a conventional power factor correction circuit.
For example, as shown in FIGS. 8 and 9, a box enclosing an AC reactor is installed outside or inside the main body of the air conditioner, and the AC reactor is connected to a power input unit. By wiring so as to be inserted into the air conditioner, harmonic countermeasures can be easily performed on the conventional power factor improving type air conditioner.

[0031]

According to the first aspect of the present invention, the resonance frequency and the level of the resonance current are adjusted by connecting the inductance component of the power supply system and the second reactor in series, thereby reducing the resonance current. Thus, there is a specific effect that the power factor can be improved by increasing the charging effect of the capacitor.

According to the second aspect of the invention, the same operation as the first aspect can be achieved. The invention of claim 3 is claim 1
The same operation as described above can be achieved. According to the fourth aspect of the invention, the same operation as the first aspect can be achieved. The invention according to claim 5 has a unique effect that it can be easily connected to an existing power supply device and can achieve the effect of reducing intermediate-order harmonics.

The invention according to claim 6 has a specific effect that it can be easily connected to an existing power supply device and can achieve the effect of reducing intermediate-order harmonics.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing one embodiment of a power supply device of the present invention.

FIG. 2 is a diagram showing waveforms at various parts of the power supply device of FIG.

FIG. 3 is a diagram illustrating a harmonic distribution in the power supply device of FIG. 1;

FIG. 4 is an electric circuit diagram showing another embodiment of the power supply device of the present invention.

FIG. 5 is an electric circuit diagram showing still another embodiment of the power supply device of the present invention.

FIG. 6 is a diagram showing waveforms at various parts of the power supply device of FIG.

FIG. 7 is a diagram showing a harmonic distribution in the power supply device of FIG. 5;

FIG. 8 is a block diagram showing an example of application to a conventional power factor improving type air conditioner.

FIG. 9 is a block diagram showing another example of application to a conventional power factor improving type air conditioner.

FIG. 10 is an electric circuit diagram showing an example of a conventional power supply device that achieves power factor improvement and harmonic reduction.

11 is a diagram showing waveforms at various parts of the power supply device of FIG. 10;

FIG. 12 is an electric circuit diagram showing a conventional power supply device for further improving the power factor.

13 is a diagram showing waveforms at various parts of the power supply device of FIG.

14 is a diagram showing a harmonic distribution in the power supply device of FIG.

[Explanation of symbols]

 2 second reactor 3 full-wave rectifier circuit 4 smoothing capacitor 5 first reactor 6 diode 7 capacitor

Claims (6)

[Claims] 1. A power supply device for rectifying an AC input voltage by a rectifier circuit (3) to apply a DC voltage to a rectifier load, wherein one of an AC side and a DC side of the rectifier circuit (3) is provided. , A series connection circuit of the first reactor (5) and the diode (6) and the capacitor (7) are connected in parallel with each other;
Furthermore, a power supply device characterized in that a second reactor (2) is connected to the AC input terminal. 2. A first reactor (5) connected between an output terminal of the rectifier circuit (3) and a positive terminal of a smoothing capacitor (4).
The power supply device according to claim 1, wherein a series connection circuit of a diode and a capacitor is connected in parallel with the capacitor. 3. A first reactor (5) between an output terminal of the rectifier circuit (3) and a positive terminal of a smoothing capacitor (4).
And a diode (6) connected in series.
The power supply device according to claim 1, wherein a capacitor (7) is connected in parallel with a series connection circuit of the reactor (5), the diode (6) and the smoothing capacitor (4). 4. A three-phase rectifier circuit is adopted as the rectifier circuit (3), and a first reactor (5) is connected between one AC input terminal and a first phase of the three-phase rectifier circuit (3). A capacitor (7) is connected in parallel with the first reactor (5) to the second phase of the three-phase rectifier circuit (3), and the other AC input terminal is connected to the third phase of the three-phase rectifier circuit (3). The power supply device according to claim 1, which is connected. 5. The power supply device according to claim 1, wherein the second reactor (2) is externally connected to an input terminal of the rectifier circuit (3). 6. The power supply device according to claim 1, wherein the second reactor is connected to a power supply system side of a power supply device inside a load device to which an AC voltage is supplied by a power supply system.