JPH0739163A - Switching power supply apparatus - Google Patents

Abstract

PURPOSE:To provide a switching power supply apparatus which can supply electric power in a prescribed time in the momentary voltage drop of an input voltage. CONSTITUTION:In a steady operation, the electric power of an AC power supply 1 which has been rectified by a bridge means 2 is sent out from a transformer T1 after its harmonic component has been removed by a harmonic-distortion improvement circuit 61 for a switching means 6 via a diode D2 and a filter circuit 5. At this time, charged electric power which has been charged in a capacitor C2 by a resistance R5 and a diode D1 is not supplied to the filter circuit 5 because a switching element Q1 is turned on and switching elements Q2, Q3 are turned off. In a momentary voltage drop, the output of a voltage- dividing time-constant circuit by resistances R1, R2 and by a capacitor C1 is at an 'L' level, the switching element Q1 is turned off, the switching elements Q2, Q3 are turned on by a resistance R3, and the charged electric power which has been charged in the C2 is sent out by the switching means 6 via a diode D3 and the filter circuit 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a 1-converter active filter type switching power supply device having a harmonic distortion countermeasure, and more particularly to a switching power supply device which prevents an instantaneous voltage drop of an input voltage.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional switching power supply device is a filter circuit of a coil L1 and a capacitor C3 for preventing harmonic frequency distortion and for preventing switching frequency noise from flowing into an input AC power supply 1. 5, the harmonic distortion improving circuit 61 superimposes the switching current proportional to the input voltage of the AC power supply 1 rectified by the bridge means 2 on the transformer T1 and sends the electric power to the load.
The one that reduces the harmonic component of the input current of the AC power supply 1 rectified by.

[0003]

As described above, the one-converter type active filter type switching in which the capacitor for reducing the harmonic distortion of the input current of the input power source is deleted and the control is performed by the input current proportional to the input voltage. Since the power source cannot use an element that stores electric power, it is vulnerable to an instantaneous voltage drop of the input voltage, and there is a problem that the output voltage is instantaneously dropped and the electronic device is reset.

Therefore, an object of the present invention is to provide a switching power supply device capable of supplying power for a predetermined time when the input voltage instantaneously drops.

[0005]

In order to solve the above-mentioned problems, the switching power supply device of the present invention has at least one of a bridge means for rectifying an input AC power supply and an AC power supply rectified by this bridge means. Detecting means for detecting a voltage drop at a predetermined voltage value within a cycle period, and when this detecting means detects a voltage drop, control is performed so as to send out charging power precharged by the rectified AC power source, or When the detection means does not detect a voltage drop, the control means controls the rectified AC power source to send out the power, and the harmonics which generate a switching current proportional to the voltage value of the power controlled by the control means. It is characterized by comprising a wave distortion improving circuit and switching means for performing switching.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a switching power supply device according to an embodiment of the first invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of a switching power supply device according to an embodiment of the first invention.

A switching power supply device according to an embodiment of the first invention is a bridge means 2 for rectifying an input AC power supply 1, and an AC power supply 1 rectified by the bridge means 2.
The voltage drop of R1 and R2 is detected by the divided value of R1 and R2 within one cycle set by the time constants of R1 and C1, and is detected by switch element Q1, R3, R4 and switch element Q2. The detecting means 3 which outputs a signal, and when this detecting means 3 outputs a detection signal, the charging power charged in the capacitor C2 via the resistor R5 and the diode D1 is sent by the diode D3 and the switching element Q3. When controlled or when the detection means 3 does not output a detection signal, the AC power source 1 rectified by the bridge means 2
Means for controlling so as to send out the electric power of the diode D2, the filter circuit 5 of the coil L1 and the capacitor C3 for preventing the outflow of the switching frequency noise to the control means 4, and the voltage of the electric power controlled by the control means 4. The harmonic distortion improving circuit 61 superimposes a switching current proportional to the value on the transformer T1 and sends the electric power.

Next, the operation of the switching power supply device according to the first embodiment of the invention will be described with reference to FIG.

In the operation of the switching power supply device according to the first embodiment of the present invention, in a steady state, the power of the AC power supply 1 rectified by the bridge means 2 is sent to the filter circuit 5 by the diode D2 of the control means 4, The harmonic distortion improving circuit 61 of the switching means 6 supplies the switching current proportional to the voltage value of the power output from the filter circuit 5 to the transformer T1.
The power is transmitted by superimposing on.

Further, via a resistor R5 and a diode D1,
The power of the AC power supply 1 rectified by the bridge means 2 is charged in the capacitor C2, and the resistors R1, R2 and the capacitor C1 are charged.
The output of the voltage division time constant circuit composed of
To maintain the base potential of the switch element Q2 at "L", the switch elements Q2 and Q3 are turned off, and the charging power charged in the capacitor C2 is not sent to the filter circuit 5.

On the other hand, in the switching power supply device according to the first embodiment of the invention, the resistors R1 and R
2, the output of the voltage division time constant circuit composed of the capacitor C1 becomes “L” level, so that the switch element Q1 is turned off and the base current flows to the switch element Q2 through the resistor R3, and the switch elements Q2 and Q3. Is turned on, and the charging power charged in the capacitor C2 is sent to the switching means 6 via the switch element Q3, the diode D3 and the filter circuit 5 to send the charging power.

Next, a switching power supply device according to an embodiment of the second invention will be described with reference to the drawings.

FIG. 2 is a circuit diagram of a switching power supply device according to an embodiment of the second invention.

In the switching power supply device according to the second embodiment of the invention, the output voltage of the tertiary winding T13 of the transformer T1 of the switching means 6 is passed through the diode D4 and the resistor R.
1, R2, 1 set by the time constant of the capacitor C1
Only the detecting means 3 which detects the instantaneous voltage drop of the AC power supply 1 rectified by the bridge means 2 and outputs the detection signal by the resistors R3, R4 and the switch element Q2 within the cycle period is one embodiment of the first invention. The configuration is the same except for the switching power supply device according to the example.

Next, the operation of the switching power supply device according to the embodiment of the second invention will be described with reference to FIG.

In the operation of the switching power supply device according to the second embodiment of the present invention, when the AC power supply 1 rectified by the bridge means 2 is momentarily lowered in voltage in a steady state, the output voltage of the tertiary winding T13 of the transformer T1 is changed. It is supplied to the voltage dividing time constant circuit composed of the resistors R1, R2 and the capacitor C1 via the diode D4, and the output becomes “L”. Therefore, the switch element Q1 is turned off and the switch element Q2 is connected to the switch element Q2 via the resistor R3. The base current flows to turn on the switching elements Q2 and Q3, and the charging power charged in the capacitor C2 is sent to the switching means 6 through the switching element Q3, the diode D3 and the filter circuit 5, and the charging power is sent out.

[0018]

As described above, according to the switching power supply device of the present invention, even in the 1-converter active filter switching power supply, when the instantaneous voltage drop of the input voltage occurs, the power can be supplied for a predetermined time. It is possible to prevent the malfunction of the electronic device due to the reset.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a switching power supply device according to an embodiment of the first invention.

FIG. 2 is a circuit diagram of a switching power supply device according to an embodiment of the second invention.

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

[Explanation of symbols]

1 AC power supply 2 Bridge means 3,13 Detection means 4 Control means 5 Switching power supply device (filter circuit) 6 Switching means 61 Harmonic distortion improvement circuit C1 Detection means (capacitor) C2 Control means (capacitor) C3 Switching power supply device (filter circuit) Capacitor) D1 to D3 control means (diode) D4 detection means (diode) L1 switching power supply device (filter circuit coil) Q1 and Q2 detection means (switch element) Q3 control means (switch element) R1 to R4 detection means (resistance) ) R5 control means (resistance) T1 switching means (transformer) T13 detection means (transformer tertiary winding)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H02M 3/28 U 8726-5H

Claims (1)

[Claims] 1. A bridge unit for rectifying an input AC power source, a detecting unit for detecting a voltage drop at a predetermined voltage value within at least one cycle period of the AC power source rectified by the bridge unit, and the detecting unit. When a voltage drop is detected, the charging power precharged by the rectified AC power supply is controlled to be sent out, or when the detecting means does not detect a voltage drop, the rectified AC power is supplied to the power supply. And a switching means for performing switching with a harmonic distortion improving circuit for generating a switching current proportional to the voltage value of the electric power controlled by the control means. Switching power supply.