JPH03118768A - Power source circuit - Google Patents

Abstract

PURPOSE:To reduce the rush currents in power making so as to decrease the loss in normal load operation by inserting an impedance element in series with a Schottky circuit for a certain time after power making. CONSTITUTION:When power is made, rush currents flow to the capacitors C2 and C3 of a Schottky circuit 3, but at this time a switch element 6 is open, and an impedance element 5 is inserted in series to the capacitors C2 and C3, so it follows that charge currents flow gradually, and rush currents are reduced. When a certain time passes after power making, a timer circuit 7 drives the switch element 6 to close the path, and by the close of this switching element 6, the impedance element 5 inserted in series with the capacitors C2 and C3 is short-circuited. Hereby, in the normal load operation after a certain time has passed since the power making, the loss by the impedance element 6 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a power supply circuit with a high power factor.

[Prior Art] For example, as a DC input power supply circuit for an inverter, as shown in the second diagram, the center tap of the input winding of an inverter transformer T is connected to a DC power supply, and the input winding is connected to capacitors C4 and C5 and a switching transistor Q1. , C
2. In an inverter in which the choke coil 4 is connected and the drive circuit 1 drives the transistors Q1 and C2 to light the discharge lamp 2 on the output winding side, the output terminal of the rectifier circuit 01 of the DC power supply and the capacitor C1 In between, two series capacitors C2, C3 and both capacitors C2,03
A Schottney circuit 3 consisting of a diode D2 between, resistors R1 and R2 in parallel with both capacitors C2 and C3, and diodes 03, D4 and D5 in series with each resistor.
A circuit that connects the two is known.

In addition, as in the discharge lamp lighting device shown in Japanese Utility Model Application No. 60-112099, a thyristor and a A parallel circuit of resistors is connected in series, and the inrush current is reduced by this resistor when the power is turned on.The power supply for the operation of the timer circuit that controls the thyristor is a circuit in which the power supply winding is installed separately on the inverter transformer. Are known.

[Problem to be Solved by the Invention] In a circuit that only includes the Schottney circuit 3 as shown in the second diagram, there is a problem that the power breaker malfunctions due to the large inrush current when the power is turned on. .

In addition, although the circuit described in the above publication is effective against inrush current, it has a large loss, and the power supply winding for the thyristor control circuit must be provided separately on the inverter transformer, so even if it is free of charge, it is difficult to use a tap. The disadvantage is that the transformer, which has a large number of components, becomes more complex, and cannot be made smaller, resulting in higher costs.

The present invention reduces inrush current when power is turned on, and
It is an object of the present invention to provide a power supply circuit which reduces loss during normal load operation and which allows the device to be simplified and downsized.

[Means for Solving the Problems] In order to achieve the above object, the power supply circuit of the present invention includes a rectifier that rectifies an alternating current voltage, a Schottney circuit provided between the output terminals of the rectifier, and a Schottney circuit that rectifies an alternating current voltage. The Schottney circuit has an impedance element inserted in series with the knee circuit for a certain period of time after power is turned on, and a switch element that short-circuits this impedance element after a certain period of time, and a power source for operating this switch element is provided on the output side of the Schottney circuit. The voltage generated by the inductor is taken from the voltage generated by the inductor.

[Function] The impedance element connected in series with the Schottney circuit is inserted in series for a certain period of time after the power is turned on, thereby reducing the rush current when the power is turned on.

Furthermore, since this impedance element is short-circuited by the switch element after a certain period of time has elapsed, the loss due to the impedance element is reduced during normal load operation after this certain period of time has elapsed. .

Since the power supply for operating the switch element is taken from the voltage generated by the input choke, there is no need to separately provide a power supply winding to the inverter transformer, resulting in a smaller device.

[Example] Embodiments of the present invention will be described below with reference to FIG.

The same numbers as in Fig. 2 indicate the same parts, 01 and C1 are the rectifier circuit and capacitor of the DC power supply, 3 is the Schottney circuit, and there are two series capacitors C2 and C3, and between these two capacitors C2 and 03. , resistors R1 and R2 in parallel with both capacitors C2 and C3, and diodes 03.04 and diode 05 in series with these resistors R1 and R2.

T is an inverter transformer whose center tap of the input winding is connected to a DC power supply, C4 and C5 are capacitors parallel to the input winding, Ql and Ql are switching transistors, 1
The drive circuit may be either automatic type or separately excited type, and these constitute what is called a push-pull type inverter. 2 is a discharge lamp that is lit by the output of this inverter, and 4 is a well-known input constant current inductor, such as a choke coil, for the push-pull type inverter.

5 is an impedance element connected in series to capacitors c2 and C3 of the Schottney circuit 3; 6 is a switch element connected in parallel to this impedance element 5; and 7 is a timer circuit for driving this switch element 6. This switch element 6 is driven by a timer circuit 7 to close the impedance element 5 after a certain period of time has elapsed since the power was turned on, thereby short-circuiting the impedance element 5.

The voltage generated by the inductor, that is, the input choke coil 4 provided on the output side of the Schottney circuit is used as the power source for operating the switch element 6 and the timer circuit 7.

For this purpose, part or all of the input choke coil 4 is used.

In the inverter circuit of the present invention configured as described above, the discharge lamp 2 is lit by the output of the inverter transformer T by alternately turning on and off the switching transistor Q1.02, and when the power is first turned on, the Schottney circuit 3 An inrush current flows through the capacitors C2 and C3, but at this time the switch element 6 is open and the impedance element 5 is inserted in series with the capacitors C2 and C3.
Charging current gradually flows through capacitors C2 and C3, reducing inrush current.

When a certain period of time elapses after the power is turned on, the timer circuit 7 drives the switch element 6 to close the circuit, and the closing of the switch element 6 short-circuits the impedance element 5 inserted in series with the capacitors C2 and C3. As a result, the loss caused by the impedance element 6 is reduced during normal load operation after a certain period of time has elapsed since the power was turned on.

In addition to the inverter circuit, the present invention may also include, for example, a choke circuit. In this case, a smoothing inductor can be used as the inductor.

[Effects of the Invention] As described above, the present invention provides an impedance element that is inserted in series with the Schottney circuit for a certain period of time after the power is turned on, so it is possible to reduce the inrush current when the power is turned on, and When normal load operation occurs after a certain period of time has elapsed, the impedance element is short-circuited by the switch element, making it possible to reduce loss.

Further, since the power source for operating the switch element is taken from the voltage generated by the inductor provided on the output side of the Schottney circuit, the device can be made smaller.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional example. 4: Input choke 3 switch circuit 5: Impedance element 6: Switch element 01: Rectifier

Claims (1)

[Claims] a rectifier that rectifies an alternating current voltage; a Schottney circuit provided between the output terminals of the rectifier; an impedance element that is inserted in series with the Schottney circuit for a certain period of time after power is turned on; 1. A power supply circuit comprising a switch element which is later short-circuited, and a voltage generated by an inductor provided on the output side of the Schottney circuit is used as a power source for operating the switch element.