JPH05300743A - Power supply apparatus - Google Patents

Abstract

PURPOSE:To reduce the distortion of AC input current waveform to contrive to improve input power factor by connecting a smoothing capacitor with both ends of a rectifier circuit part via switching element and by placing the switching element in ON state for a period while the waveform of pulsating DC voltage is lower than a predetermined level. CONSTITUTION:A load circuit part 3 is connected with both ends of a rectifier circuit part 2 via diode D1 and a smoothing capacitor Cg is connected with both ends of the load circuit part 3. On the other hand, the series circuit of smoothing capacitor C1 and switching element 7 is connected with the both ends of the rectifier circuit part 2 via the series circuit of a forward diode D2 and current-limiting impedance 6. The pulsating DC voltage A of the output point of a control circuit 5 and rectifier circuit 2 outputs the control signal B, which is turned OFF at a predetermined level or higher, and turns ON the switching element 7 under the predetermined level. In this manner, it is possible to shorten the generation interval of the pulse current of AC current IIN, to improve the distortion of waveform and to improve input power factor.

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 electric power to a load.

[0002]

2. Description of the Related Art Conventionally, as this type of power supply device, one shown in FIG. 6 is often used. The configuration is AC power supply 1
Is connected to both ends of the rectifier circuit unit 2, smoothing capacitors C0 are connected to both ends of the rectifier circuit unit 2, and smoothing capacitor C0
The load circuit unit 3 is connected to both ends of the rectifier circuit, and the pulsating DC voltage output from the rectifying circuit unit 2 upon receiving the AC voltage VIN of the AC power supply 1 becomes a DC voltage smoothed by the smoothing capacitor C0. It is supplied to the circuit unit 3. The waveform of each part in this case is a sine wave voltage waveform of the AC voltage VIN, as shown in FIG. 7, the AC input current IIN is a pulse-shaped current waveform, and the current waveform is distorted. Becomes

On the other hand, in the case of the lighting circuit, as shown in FIG. 8, the discharge lamp 3 is provided at both ends of the AC power source 1 through the current limiting element 10.
Is connected and the discharge lamp 3 is turned on by receiving the AC voltage VIN of the AC power supply 1. However, as shown in FIG.
A current quiescent section occurs at IN, and the AC input current waveform is distorted, resulting in a low input power factor.

Therefore, in order to obtain a power supply device with a low distortion of the AC input current waveform and a high input power factor, the AC input current IIN is less likely to have a rest period, and the AC input current IIN is equal to the AC voltage VIN. That is, it should be similar to the sinusoidal voltage waveform.

It is known to reduce the occurrence of idle periods generated in the AC input current IIN. The one disclosed in Japanese Examined Patent Publication No. 59-19434 is an example thereof. The configuration is the AC voltage of the AC power supply 1 (commercial power supply 1
When the pulsating current DC voltage output from the rectification circuit unit 2 in response to the high voltage of 00V and 200V is higher than the lamp voltage of the discharge lamp 3, it is applied to the main inverter circuit unit 91 and the high frequency of the main inverter circuit unit 91. The voltage is applied to the discharge lamp 3 and maintained to be lit, and when the voltage is equal to or lower than the lamp voltage of the discharge lamp 3, the pulsating direct current voltage is applied to the auxiliary inverter circuit unit 92 and the high frequency voltage of the auxiliary inverter circuit unit 92 is released. Preheating is continued by being applied to the filament (not shown) of the electric lamp 3.

With this structure, the discharge lamp 3
Although the AC input current does not flow to the main inverter circuit section 91 in the extinguished section, the combined AC input current flows in the dormant section because the AC input current flows to the auxiliary inverter circuit section 92 in the extinguished section. Can be few.

However, in such a configuration, for example, the control power source of the control circuit section such as an IC is generally formed with a voltage of not more than ten and several V, and therefore, as shown in FIGS. 11 and 12. It is necessary to separately obtain a stable low-voltage DC voltage using a step-down transformer or voltage divider circuit. In this case,
There is a problem that the power loss of the circuit becomes large.

[0008]

The problem to be solved is that the AC input current IIN has a quiescent section in the current and the waveform of the AC input current is distorted to lower the input power factor. The point is that the step-down means for obtaining a low voltage requires a large amount of power loss. The object of the present invention is that the circuit configuration is easy, there is no increase in loss, and the input power factor is It is to provide a power supply device that can be improved.

[0009]

According to the present invention, there is provided a rectifying circuit section which receives an alternating voltage of an alternating current power source and outputs a pulsating direct current voltage,
A smoothing capacitor connected to both ends of the rectifying circuit unit via a switching element, and a control circuit unit for turning off the switching element when the pulsating current DC voltage is equal to or higher than a predetermined level. To do.

[0010]

According to the present invention, the rectification circuit section is connected to both ends of the AC power supply, the smoothing capacitors are connected to both ends of the rectification circuit section through the switching elements, and the pulsating current DC voltage output from the rectification circuit section is predetermined. When the level is equal to or higher than the level, the switching element is turned off by the control circuit unit, so that the maximum level of the voltage across the smoothing capacitor can be made lower than the predetermined level of the pulsating direct current voltage. As a control power supply, the distortion of the AC input current waveform can be reduced, and the input power factor can be improved.

[0011]

FIG. 1 is a circuit configuration diagram showing a first embodiment of the present invention, in which a pulsating direct current voltage VG-A is received by an AC power source 1 and is applied to a load such as an inverter device. The rectifying circuit section 2 which outputs to the circuit section 3, the smoothing capacitor C1 which is connected to both ends of the rectifying circuit section 2 via the switching element 7, and the pulsating current DC voltage VG-A is above a predetermined level, A control circuit section 5 for turning off the switching element 7 is provided, and a control power supply 4 for controlling the load circuit section 3 is obtained from both ends of the smoothing capacitor C1.

Here, the load circuit section 3 is connected to both ends of the rectifying circuit section 2 through the diode D1 and the load circuit section 3 is connected.
A smoothing capacitor C0 is connected to both ends of. Then, the DC voltage VG-D having a small ripple amount of the voltage across the smoothing capacitor C0 is applied to the load circuit section 3. At this time, the current IF is flowing through the diode D1. A series circuit of the smoothing capacitor C1 and the switching element 7 is connected to both ends of the rectifier circuit unit 2 through a series circuit of a forward diode D2 and a current limiting impedance 6.
Then, the DC voltage VG-C having a small ripple amount of the voltage across the smoothing capacitor C1 is applied to the control power supply 4.

Further, the control circuit section 5 has a pulsating direct current voltage VG-
The control signal B that is turned off at a predetermined level of A or higher and the control signal B that is turned on at a predetermined level or lower is output to the switching element 7. At this time, the current IE is flowing through the switching element 7. And the AC input current I
IN is a combined current of the current IF and the current IE.

The operation state will be described below with reference to the operation explanatory diagram shown in FIG. First, receiving the 100V AC voltage of the AC power supply 1, the pulsating current DC voltage VG-A shown in FIG. 7A, which is the output of the rectifier circuit unit 2, is smoothed by the smoothing capacitor C0, A DC voltage VG-D of about 141 V shown in is applied to the load circuit section 3. At this time, the current IF shown in FIG. 6 (f) flows through the diode D1.

Next, the switching element 7 such as a transistor is turned on only while the pulsating DC voltage VG-A is below a predetermined level (period ta), and the smoothing capacitor C1 is charged as shown in FIG. Supply current IE. At this time,
The voltage across the smoothing capacitor C1 is the pulsating DC voltage VG-A.
The predetermined level and the maximum level are substantially equal to the voltage VG-C shown in FIG.

With this configuration, the maximum level of the voltage across the smoothing capacitor C1 is set to be less than the predetermined level of the pulsating direct current voltage, and the voltage VG-C across the smoothing capacitor C1 can be used as the control power supply. Moreover, as compared with the AC input current IIN shown in FIG. 7 of the conventional example, the generation interval of the pulsed current is shortened as shown in FIG. 7 (g) to improve the distortion of the waveform of the AC input current IIN. The power factor can be improved.

If the switching element 7 is a unidirectional element, the diode D2 is unnecessary and the current I
It goes without saying that if the value of E is small, the current limiting impedance 6 is unnecessary.

FIG. 2 is a circuit configuration diagram showing a second embodiment of the present invention and shows a specific circuit configuration of the first embodiment.

A rectifier circuit section 2 for receiving an AC voltage of an AC power source 1 and outputting a pulsating DC voltage to a load circuit section 3 such as an inverter device, and a diode D2 and a switching element 7 at both ends of the rectifier circuit section 2. A smoothing capacitor C1 connected via the smoothing capacitor C1 and a control circuit unit 51 for turning off the switching element 7 when the pulsating DC voltage is equal to or higher than a predetermined level (voltage of the Zener diode ZD1). The control power source 4 is connected to both ends of the.

Here, the control circuit section 51 includes the rectifying circuit section 2
A series circuit of a resistor R2 and a switching element Q1 connected to both ends of the switching element Q1 via a diode D1, and a Zener diode ZD1 and a resistor R1 connected between the positive side of the rectifier circuit section 2 and the base end of the switching element Q1. It is connected between the series circuit, the forward diode D1 connected between the collector terminal of the switching element Q1 and the control terminal of the switching element 7, and the control end of the switching element 7 and the positive electrode side of the smoothing capacitor C1. And a parallel circuit of a Zener diode ZD2 and a resistor R3. A Zener diode ZD3 is connected to both ends of the smoothing capacitor C1.

The operation state will be briefly described below. First,
Upon receiving the AC voltage of the AC power supply 1, a pulsating DC voltage is output to both ends of the rectifier circuit unit 2. This pulsating direct current voltage is detected by the Zener diode ZD1 (10 V for explanation), and when the pulsating direct current voltage is 10 V or more, the switching element Q1 is turned on. Switching element Q
1 is turned on, the switching element Q in which the DC voltage (approximately 141 V) across the smoothing capacitor C0 is turned on
It is applied to the resistor R2 via 1 and a predetermined current flows.
Then, the voltage of the control terminal of the switching element 7 drops, and the switching element 7 is turned off. Therefore, the voltage of the smoothing capacitor C1 is discharged to the control power supply 4.

Next, when the pulsating DC voltage is less than 10V, the switching element Q1 is turned off. When the switching element Q1 is turned off, the DC voltage across the smoothing capacitor C0 is turned off.
1, the voltage of the control terminal of the switching element 7 rises, and the switching element 7 is turned on. Therefore, the charging current flows through the smoothing capacitor C1, and the terminal voltage rises to the maximum level of 10V.

The value of the Zener diode ZD2 is
It is set so as not to exceed the maximum allowable voltage between the gate and the source of the switching element 7. The resistor R2 is
The switching element Q2 is inserted in order to prevent the charge from being accumulated and maintaining the ON state.

FIG. 3 is a circuit configuration diagram showing a third embodiment of the present invention. The configuration different from that of the second embodiment is shown in FIG.
The smoothing capacitor C0 shown in (1) is a half buried circuit.

Here, the ½ valley buried circuit includes a series circuit of a capacitor C11, a forward diode D12 and a capacitor C10 connected to both ends of the rectifier circuit section 2, and a capacitor C11 and a forward diode D12. The diode D13 is connected in anti-parallel to the series circuit, and the diode D13 is connected to the series circuit of the forward diode D12 and the capacitor C10 and is connected in anti-parallel to the series circuit of diodes D11, D14, D15. 1/2 of the peak value (about 141V in case of 100V AC power supply), that is,
When the voltage is about 70V or less, the capacitor C11 and the capacitor C
10 is connected in parallel and a current flows through the load circuit unit 3, and when the voltage is about 70 V or more, the capacitor C11 and the capacitor C are connected.
10 and 10 are connected in series and are charged by the pulsating current DC voltage.

Therefore, only when the voltage is about 70 V or less, the capacitor C11 → the load circuit section 3 → the resistor R13 → the base-emitter of the switching element Q11 → the diode D11.
→ A current flows in a closed loop reaching the capacitor C11 and the switching element Q11 is turned on. Then, the switching element 7 is turned on, and the charging current flows through the smoothing capacitor C1 as in the previous embodiment. Hereinafter, the operation and effect are the same as in the previous embodiment, as shown in FIG.
The input power factor can be improved by improving the distortion of the IN waveform.

[0027]

According to the present invention, a rectifying circuit unit for receiving an AC voltage of an AC power source and outputting a pulsating DC voltage, a smoothing capacitor connected to both ends of the rectifying circuit unit via switching elements, and Since the control circuit unit that turns off the switching element when the flow DC voltage is equal to or higher than a predetermined level is provided, the maximum level of the voltage across the smoothing capacitor can be made lower than the predetermined level of the pulsating DC voltage. ,
The voltage across the smoothing capacitor can be used as the control power source, distortion of the AC input current waveform can be reduced, and
There is a remarkable effect that the input power factor can be improved.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a waveform of each part for explaining the first embodiment of the present invention.

FIG. 3 is a circuit configuration diagram showing a second embodiment of the present invention.

FIG. 4 is a circuit configuration diagram showing a third embodiment of the present invention.

FIG. 5 is an explanatory diagram showing waveforms of various parts for explaining a third embodiment of the present invention.

FIG. 6 is a circuit configuration diagram showing a conventional example of the present invention.

FIG. 7 is an explanatory diagram showing waveforms at various portions for explaining a conventional example of the present invention.

FIG. 8 is a circuit configuration diagram showing a conventional example of the present invention.

FIG. 9 is an explanatory diagram showing waveforms at various parts for explaining a conventional example of the present invention.

FIG. 10 is a circuit configuration diagram showing a conventional example of the present invention.

FIG. 11 is a circuit configuration diagram showing a conventional example of the present invention.

FIG. 12 is a circuit configuration diagram showing a conventional example of the present invention.

[Explanation of symbols]

 1 AC power supply 2 Rectifier circuit section 5 Control circuit section 7 Switching element C1 Smoothing capacitor

Claims (2)

[Claims] 1. An AC power supply, a rectifying circuit section for receiving an AC voltage of the AC power supply and outputting a pulsating DC voltage, a smoothing capacitor connected to both ends of the rectifying circuit section via switching elements, and A power supply device comprising: a control circuit unit that turns off the switching element when the pulsating DC voltage is equal to or higher than a predetermined level. 2. The load circuit section is connected to both ends of the rectifier circuit section, and a control power supply for controlling the load circuit section is obtained from both ends of the smoothing capacitor. Power supply.