JPH07143752A - Power supply device - Google Patents

Abstract

PURPOSE:To improve an input power factor excellently, and to reduce input current distortion. CONSTITUTION:An output from a full-wave rectifying circuit 1 is smoothed partially by a partial smoothing circuit 2, the pause period of input currents is shortened, and an input power factor is improved while the distortion of input currents is reduced. A filter circuit 4 weakening input currents is mounted between an AC power supply AC and the full-wave rectifying circuit 1, and the input power factor is further enhanced while the distortion of input currents is lowered. A power supply device can be constituted by providing the partial smoothing circuit 2, installing an inductor L2 suppressing the charging currents of a capacitor to the partial smoothing circuit 2 and using an inductor and a capacitor having small capacity as an inductor L1 and a capacitor C3 for the filter circuit 4.

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 supplying a DC power obtained by rectifying and smoothing an AC power supply to a load.

[0002]

2. Description of the Related Art As a power supply device for supplying a load with DC power obtained by rectifying and smoothing an AC power supply, a full-wave rectification circuit such as a diode bridge for full-wave rectification of the AC power supply, and an output of this full-wave rectification circuit A so-called capacitor input type which is composed of a smoothing capacitor for smoothing is generally used. However, such a capacitor input type power supply device has a problem that the input current has a pulse-like waveform, the input power factor is low, and the waveform distortion of the input current is very large.

Therefore, a power supply device for improving the input power factor and reducing the waveform distortion of the input current is disclosed in Japanese Examined Patent Publication No. 63-67435.
It has been proposed in the publication. In this power supply device, a filter circuit is provided on the input side of the full-wave rectification circuit that constitutes the above-mentioned capacitor input type power supply device. Here, the filter circuit is composed of an inductor inserted in one of the power supply paths to the rectifier circuit of the AC power source and a capacitor connected in parallel to the input of the rectifier circuit. In this power supply device, the resonance frequency of the filter circuit is set to 2.2 to 2.6 times the frequency of the AC power supply, and the apparent power of the inductor is approximately 0.6 times the effective power supplied from the AC power supply to the power supply device. Then, the input power factor is improved and the waveform distortion of the input current is reduced. The filter circuit acts so as to dull (waveform) the pulsed input current of the capacitor input type power supply device,
The input power factor is improved and the waveform distortion of the input current is reduced.

Another power supply device for improving the input power factor and reducing the waveform distortion of the input current as compared with the above-mentioned capacitor input type power supply device is Japanese Patent Publication No. Sho 63-375.
There is one proposed in Japanese Patent Publication No. 84. This power supply is
As shown in FIG. 3, the full-wave rectification circuit 1 including a diode bridge for full-wave rectification of the AC power supply AC and the partial smoothing circuit 2 for partially smoothing the output of the full-wave rectification circuit 1 are configured. A feature is that the partial smoothing circuit 2 is used instead of the smoothing capacitor of the capacitor input type power supply device.

The partial smoothing circuit 2 is a series circuit composed of capacitors C ₁ and C ₂ having substantially equal capacities and a diode D ₁ inserted between the capacitors C ₁ and C ₂ .
Connected to the output of the full-wave rectifier circuit 1, a diode D ₂ is connected in parallel to the series circuit of the capacitor C ₁ and the diode D ₁ with the positive side of the full-wave rectifier circuit 1 as the anode, and the diode D ₁ and the capacitor C ₂ are connected. Full-wave rectifier circuit 1 in series circuit with
The diode D ₃ is connected in parallel with the negative electrode side of the as a cathode. The diode D ₁ is connected between the capacitors C ₁ and C ₂ with the negative side of the full-wave rectifier circuit 1 as the cathode.

The partial smoothing circuit 2 of the power supply device is as follows.
To work. When AC power is supplied, all
The full-wave rectified output (pulse
Flow output) is supplied to the partial smoothing circuit 2. Note that FIG.
(B) is each capacitor C₁, C ₂Applied to both ends of
Voltage. Now, the output voltage of full-wave rectifier circuit 1 rises
Time t in the middle of₁Full-wave rectifier circuit
Capacitor C than the output voltage of 1₁, C₂The voltage across
If the added voltage is low, the capacitor C₁, C₂Is
Diode D₁In series with the output of the full-wave rectifier circuit 1 via
It is connected and charged with the output of the full-wave rectifier circuit 1. This
Indexer C₁, C₂Is the output of full-wave rectifier circuit 1
Time t when the voltage reaches its peak₂Connected in series until
Capacitor C₁, C₂Is a full-wave voltage
It is charged until it becomes equal to the peak value of the output voltage of current circuit 1.
Be done. Each of the above capacitors C₁, C₂Figure of voltage across
4 (c).

When the output voltage of the full-wave rectifier circuit 1 drops after the time t ₂ , the voltage across the capacitors C ₁ and C ₂ is maintained at the voltage state at the time t _2, so that the capacitor C ₁ , The voltage obtained by adding the voltages across C ₂ becomes higher than the output voltage of the full-wave rectifier circuit 1, the diode D ₁ is reverse biased and turned off, and the charging of the capacitors C ₁ and C ₂ is stopped.

Then, when the output voltage of the full-wave rectifier circuit 1 further decreases and the output voltage of the full-wave rectifier circuit 1 becomes lower than the voltage across the capacitors C ₁ and C ₂ (time t ₃ in FIG. 4), diode D _2, D ₂ is forward biased turned on, is connected in parallel with the capacitor C _1, C ₂ is the load (in FIG. 3 the load indicates the case where the inverter 3), each capacitor C _1, Electric power is supplied to the inverter 3 by using the charged electric charge of C ₂ as a power source. At this time, each diode forming the full-wave rectification circuit 1 is in a reverse bias state, and the supply of power to the inverter 3 of the AC power supply AC via the full-wave rectification circuit 1 is stopped.

In this state, the output voltage of the full-wave rectifier circuit 1 is
Capacitor C₁, C₂Higher than the voltage across each of
Will continue until. And the output voltage of the full-wave rectifier circuit 1 is
Capacitor C₁, C₂Higher than the voltage across each of
And (time t in FIG._Four), Diode D₂, D₃But
Reverse-biased to off, and at the same time full-wave rectifier circuit 1
The inverter 3 is supplied with electric power. And time t_Five
And capacitor C₁, C ₂Than the voltage across the series circuit
When the output voltage of the wave rectifier circuit 1 becomes high, the time t₁
Capacitor C as described in₁, C₂Is charged
It After that, the above operation is repeated.

The output voltage of the power supply device has the waveform shown in FIG. The current flowing through the full-wave rectifier circuit 1 excluding the current flowing through the partial smoothing circuit 2 has the waveform shown in FIG. 4 (e), and the current flowing through the partial smoothing circuit 2 has the waveform shown in FIG. 4 (f). Therefore, the input current as the power supply device has the waveform shown in FIG. 4 (g) to which the currents in FIGS. 4 (e) and 4 (f) are added.

[0011]

In the former power supply device described above, in order to suppress the steep current change of the input current,
It is necessary to prevent the inductor from saturating, an inductor with a large capacity (inductance) is required, and a capacitor input type power supply device has a very long idle period. However, there is a problem that the shape of the filter circuit becomes large.

In the latter case, although the input power factor and the input current waveform can be improved to some extent as compared with the capacitor input type power supply device, even in this case, there is a quiescent period in the input current. Therefore, further improvement was necessary. That is, in this latter power supply,
This is because it is difficult to suppress the input power factor and the input current waveform distortion within the range defined by the IEC standard and the like.

The present invention has been made in view of the above points, and an object of the present invention is to provide a power supply device which can improve the input power factor satisfactorily and can reduce the input current distortion. .

[0014]

In order to achieve the above object, the present invention comprises a rectifying circuit for rectifying an AC power supply and a smoothing circuit for smoothing the output of the rectifying circuit. A power supply device that supplies the obtained DC power to a load, wherein the smoothing circuit is turned on when a plurality of capacitors and the output voltage of the rectifying circuit is higher than the voltage obtained by adding the voltages across the plurality of capacitors, When each capacitor is connected in series with the output of the rectifier circuit and each capacitor is charged in series with the output of the rectifier circuit, and the output voltage of the rectifier circuit is lower than the voltage that is the sum of the voltages across the capacitors. 1 to a plurality of first switching means to be turned off, and turned on when the voltage across each capacitor is higher than the output voltage of the rectifier circuit, and each capacitor is connected in parallel to the load. Te, along with parallel discharge the charged electric charges of each capacitor to the load, a plurality of voltage across each capacitor is turned off when lower than the output voltage of the rectifier circuit a second
The switching element and the plurality of capacitors are inserted in a series charging path in a series circuit in which the capacitors are connected in series via the first diode, and at a position deviated from the parallel discharging path of each capacitor. A filter circuit composed of an inductor that is configured with a current limiting element that suppresses the charging current and that is inserted in one of the power supply paths to the rectifier circuit of the AC power source, and a capacitor that is connected in parallel to the input of the rectifier circuit. It is provided.

The simplest configuration of the smoothing circuit is as follows.
As set forth in claim 2, two capacitors, a first diode inserted between the respective capacitors with the cathode being the negative side of the rectifier circuit, and the first diode and the first diode inserted between the respective capacitors. And a current limiting element that is connected in series to the output of the rectifier circuit,
In the series circuit of the diode and the current limiting element, the second diode is connected in parallel with the anode as the positive electrode side, and in the series circuit of the capacitor on the negative electrode side and the first diode and the current limiting element with the cathode as the negative electrode side. There is a method of connecting the second diode in parallel.

[0016]

According to the present invention, the so-called partial smoothing circuit is used in place of the smoothing capacitor of the capacitor input type power supply device as described above, thereby shortening the quiescent period of the input current and improving the input power factor. Reduce the distortion of the input current waveform. Further, a filter circuit is provided between the AC power supply and the rectifier circuit to dull the input current of the power supply device to further improve the input power factor and reduce the distortion of the input current waveform. A so-called partial smoothing circuit is used in place of the smoothing capacitor of the capacitor input type power supply device, and the idle period of the input current is shortened, so that the filter circuit can be configured with a small inductor and capacitor. Furthermore, by providing a current limiting element that suppresses the current when the capacitor is charged in the partial smoothing circuit, the charging current that flows when the capacitor in the partial smoothing circuit is charged is blunted, and as an inductor that further blunts the filter circuit, especially the input current. It is possible to use a small one.

[0017]

FIG. 1 shows an embodiment of the present invention. In the power supply device of the present embodiment, the filter circuit 4 of Japanese Patent Publication No. 63-67435 is provided between the AC power supply AC and the full-wave rectifier circuit 1,
As in Japanese Patent Publication No. 63-37584, the partial smoothing circuit 2 is used instead of the smoothing capacitor. However,
In the partial smoothing circuit 2 of the present embodiment, the inductor L ₂ as a current limiting element is inserted between the capacitors C ₁ and C ₂ together with the diode D _{1 and} the partial smoothing circuit of Japanese Patent Publication No. 63-37584. Different from 2. In addition, the filter circuit 4
Is a circuit condition exactly the same as the filter circuit of Japanese Patent Publication No. 63-67435 as long as the waveform of the input current of the full-wave rectifier circuit 1 is shaped to improve the input power factor and reduce the waveform distortion. It is not necessary to have. Note that FIG. 1 shows a case where the power supply device according to the present invention is used for a discharge lamp lighting device, and the output of the power supply device is supplied to an inverter 3, and the inverter 3 is configured to light the discharge lamp La at a high frequency. .

Now, when there is no inductor L ₂ in the partial smoothing circuit 2 in FIG. 1, the current flowing through the full-wave rectifying circuit 1 and the partial smoothing circuit 2 has the waveform shown in FIG. 4 (g). In this embodiment, a filter circuit 4 is provided between the AC power supply AC and the full-wave rectifier circuit 1 in order to shape the waveform of this current. This filter circuit 4 can shape the waveform of the input current of the full-wave rectifier circuit 1, improve the input power factor, and reduce the waveform distortion. Here, when the partial smoothing circuit 2 is used, the quiescent period of the input current of the full-wave rectifier circuit 1 becomes shorter than that of the capacitor input type power supply device, so that the inductor L ₁ and the capacitor C constituting the filter circuit 4 are reduced.
It is possible to use a small capacity as ₃ , that is, a small capacity.

By the way, in the partial smoothing circuit 2, the impedance is low and a steep current flows when the capacitors C ₁ and C ₂ are charged. At this time, inductor L
_{Since 1} is saturated, the waveform of the input current during charging shown in FIG. 4 (f) cannot be shaped. Therefore, in this embodiment, the inductor L ₂ is inserted in series with the diode D ₁ so as to dull the input current shown in FIG. 4 (f) when the capacitors C ₁ and C ₂ are charged. Thus inductor L ₂
By suppressing a steep current change at the time of charging the capacitors C ₁ and C ₂ , the inductor L ₁ of the filter circuit 4 is suppressed.
Also, the capacitor C ₃ , especially the _one having a small capacitance can be used as the inductor L ₁ , and the shape of the filter circuit 4 can be reduced.

[0020] Incidentally, the inductor L ₂ is in the charging path capacitor C _1, C ₂ in the partial smoothing circuit 2, so and are inserted into the portion not included in the discharge path of the capacitor C _1, C _2, It has no influence on the discharge of the capacitors C ₁ and C ₂ . Further, although the inductor L ₂ is used as the current limiting element in this embodiment, the current limiting element does not necessarily have to be an inductor, and the same effect can be obtained even if it is a resistor.

By the way, when the power supply device is applied to a discharge lamp lighting device using the inverter 3, the power supply device supplies an output voltage having a waveform shown in FIG. The current shown in FIG. Here, as shown in FIG. 2B, there is a ripple component in the current flowing through the inverter 3, so it may be necessary to re-ignite the discharge lamp La depending on the output voltage of the power supply device.

As a method of eliminating the need for this re-ignition,
As shown in FIG. 2C, a portion where the output voltage of the full-wave rectifier circuit 1 is low (so-called valley portion) is smoothed by the partial smoothing circuit 2 and a portion where the output voltage of the full-wave rectifier circuit 1 is high. It suffices to reduce the voltage difference. But to do this,
It is necessary to increase the capacitance of the capacitors C ₁ and C ₂ ,
This causes a problem that a current (FIG. 4 (f)) flowing when charging the capacitors C ₁ and C ₂ becomes large. There is also a method of suppressing the ripple component by switching control on the side of the inverter 3, but in this case as well, there arises a problem that the current flowing when charging the capacitors C ₁ and C ₂ becomes large. In this case, if the filter circuit 4 is used alone to suppress the current, it is necessary to increase the capacitance (inductance) of the inductor L ₁ .

However, since the inductor L ₂ is provided in the partial smoothing circuit 2 in this embodiment, the current can be suppressed by the inductor L ₂ and the inductor L ₁ of the filter circuit 4 does not have to be large. I'm done. Therefore, the power supply device is particularly effective when applied to a discharge lamp lighting device using the inverter 3.

[0024]

As described above, according to the present invention, the output of the rectifier circuit is partially smoothed by the so-called partial smoothing circuit, so that the quiescent period of the input current is shortened and the input power factor is improved. The distortion of the input current can be reduced,
Moreover, since a filter circuit that blunts the input current is provided between the AC power supply and the rectifier circuit, the input power factor can be further improved and the distortion of the input current can be reduced, which improves the input power factor satisfactorily. In addition, the input current distortion can be reduced. Further, since the partial smoothing circuit is provided and the current limiting element that suppresses the charging current of the capacitor is provided in this partial smoothing circuit, it is possible to configure the inductor and the capacitor of the filter circuit with a small capacitance. There is an advantage that the shape does not become large.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an effect when the same is applied to a discharge lamp lighting device.

FIG. 3 is a circuit diagram of a conventional power supply device.

FIG. 4 is an operation explanatory diagram of the above.

[Explanation of symbols]

1 Full Wave Rectifier Circuit 2 Partial Smoothing Circuit 3 Inverter 4 Filter Circuit AC AC Power Supply L ₁ , L ₂ Inductor C ₁ ~ C ₃ Capacitor D ₁ ~ D ₃ Diode

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masahiro Yamanaka 1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.

Claims (2)

[Claims] 1. A power supply device comprising a rectifying circuit for rectifying an AC power supply and a smoothing circuit for smoothing an output of the rectifying circuit, the DC power obtained by rectifying and smoothing an AC power supply to a load. The smoothing circuit is turned on when the output voltage of the plurality of capacitors and the rectifier circuit is higher than the voltage obtained by adding the voltages across the plurality of capacitors, and each capacitor is connected in series to the output of the rectifier circuit. Each capacitor is serially charged by the output of the rectifier circuit, and is turned off when the output voltage of the rectifier circuit is lower than the voltage obtained by adding the voltages across the plurality of capacitors. It turns on when the voltage across the capacitors is higher than the output voltage of the rectifier circuit, each capacitor is connected in parallel to the load, and the charge stored in each capacitor is discharged in parallel to the load. A plurality of second switching elements that are turned off when the voltage across each capacitor is lower than the output voltage of the rectifier circuit; and series charging in a series circuit that connects the plurality of capacitors in series via a first diode. It is inserted in the path and at a place off the parallel discharge path of each capacitor, and is composed of a current limiting element that suppresses the charging current during series charging of the capacitor, and is connected to one of the power supply paths to the rectifier circuit of the AC power supply. A power supply device comprising a filter circuit including an inserted inductor and a capacitor connected in parallel to an input of a rectifier circuit. 2. The smoothing circuit includes two capacitors,
A first diode inserted between the respective capacitors with the cathode being the negative electrode side of the rectifying circuit, and a current limiting element inserted between the first diode and the respective capacitors with respect to the output of the rectifying circuit. In series connection, a second diode is connected in parallel with the anode on the positive electrode side in a series circuit of the positive electrode side capacitor, the first diode and the current limiting element, and the negative electrode side capacitor, the first diode and the current limiting element are connected. 2. The power supply device according to claim 1, wherein the second series diode is connected in parallel to the series circuit having the cathode as the negative electrode side.