JPS6126474A - Power source equipment - Google Patents

Abstract

PURPOSE:To reduce the surge voltage by initially charging a smoothing capacitor when a switch is closed, and then applying a voltage to both inverter oscillators of an inverter, thereby decreasing the voltage applied to the oscillator. CONSTITUTION:When a power source switch S is closed, smoothing capacitors C1, C2 are charged through a switch SW of ON state, and when a switch SW is opened, a voltage of (the both terminal voltage of the capacitor C2 + both terminal voltage of a diode D1) is simultaneously applied to an inverter oscillator A2, a voltage of (both terminal voltage of the capacitor C1 + both terminal voltage of a diode D1) is applied to an inverter oscillator A1, thereby starting operation. The transistors Q1, Q2 of the inverters A1, A2 are alternately turned ON and OFF, and a DC output voltage is led to the secondary winding of an oscillation transformer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a power supply device used to supply DC power to a pair of load sections.

[Background technology]

FIG. 5 shows a circuit diagram of a conventional example, and this conventional example circuit is constructed as follows. An AC power supply EK rectifier circuit B is connected, and one oscillating part A of the inverter circuit A is connected between the rectified output terminals via a first smoothing cocidenser C1.
, is connected and still has a second smooth coil C2
The other oscillation section A1 of the inverter circuit A is connected through the inverter circuit A. A diode D is connected between the smoothing capacitors C1 and C3 in a direction opposite to the rectification direction, and is configured to discharge the charges in the smoothing capacitors CX and C2. Thus, this conventional circuit has the advantage that the input power factor is significantly improved compared to the case where the diode D is not provided and a smoothing capacitor is directly connected to the output of the rectifier circuit (not shown). When the voltage value of and is supplied to the second inverter oscillating section A, so that the inverter oscillating sections A1, A,
There is no interruption in the current supplied to the smoothing capacitors C, , C, and the inrush current flowing to the smoothing capacitors C, C, when the power is turned on can be limited by the impedance of the inverter oscillator A1, A. C,
,C.

This has the advantage of being able to prevent excessive current from flowing. However, in such conventional examples,
When the power switch S is turned on, the first and second smoothing capacitors C1, C, become low voltage, and the high voltage after rectification of the AC power source E remains as it is in the inverter oscillation parts A1 and A! Since the voltage is applied to the transistors Ql, Q! had the disadvantage of generating surge voltage.

[Purpose of the invention]

The present invention has been made in order to solve the above-mentioned drawbacks of the conventional example, and the present invention is to first charge the smoothing capacitor at the time of power-on, and then apply voltage to both inverter oscillation parts of the inverter circuit. Therefore, it is an object of the present invention to provide a power supply device that can reduce the voltage applied to these inverter oscillation sections and, as a result, reduce the surge voltage generated in the transistors.

[Disclosure of the invention]

(Example 1) The configuration of the present invention will be described below with reference to illustrated embodiments. 1st
The figure is a circuit diagram of a first embodiment of the present invention. AC power supply E
A rectifier circuit B consisting of a diode bridge is connected to K via a power switch S, and one oscillation section of the inverter circuit A is connected between the DC output terminals of this rectifier circuit B via a first smoothing capacitor C1. A is connected,
Further, the other oscillation section A1 of the inverter circuit A is connected via the second smoothing capacitor C1. A diode D is connected between the smoothing capacitors C1 and C8 in a direction opposite to the #-t1 rectification direction, so as to discharge the charges in the smoothing capacitors C1 and C3. A switch swt- consisting of a contact point of a timer relay Ry is provided in parallel with this diode D1, and when the power switch S is turned on, a smoothing condenser +jct is connected via the switch SW which is in the on state.
, Ct are sufficiently charged and turned off, and at the same time, the inverter oscillating section A has (voltage across smoothing capacitor C3, Vc,) + (voltage across diode D1, VD, ).
A voltage of
voltage is applied to start operation. Next, the collectors of the transistors QI and Q in the inverter oscillation parts A1 and A of the inverter circuit A are respectively connected to the primary windings n1 and pnR of the oscillation transformer T. . Feedback windings n4+118 of the oscillation transformer T% are connected between the base terminals of the transistors Q+tQ1, respectively, so that the transistors Qs=Q* are turned on and off alternately. When the transistors Q1-Q* are turned on, the iron core of the oscillation transformer T1 is alternately excited in the opposite direction by the current flowing through the primary winding n1s''*.The resistor R1#R* is connected to the transistor Q1,
It is a bias resistor for starting Q*, and is a capacitor 1j for resonance of capacitors Cs and Ct#i. The high frequency voltage vH generated in the secondary winding n3 of the oscillation transformer T1 is caused by the diode D! After being rectified by the smoothing capacitor C
5 to obtain a DC output voltage Vo.

FIGS. 2(a) to 2(e) are explanatory diagrams of the operation of the embodiment shown in FIG. 1. FIG. 2(a) shows the voltage ■E of the AC power source E, and FIG. 2(b) shows the current Is flowing from the AC power source E into the rectifier circuit B. Also, in the same figure (c), the current Ic1 flowing through the I/i smoothing capacitor C1 and the smoothing capacitor C!
Current flowing in Ic! The figure (d) shows the high frequency voltage VH generated in the secondary winding n of the oscillation transformer T1, and the figure (e) shows the DC voltage Vo charged to the output smoothing capacitor C'ffi. ing. As is clear from the above figures, when the voltage VE of the AC power source E is high (at the tie three in Fig. 2, tt~j!, j*~i4, j
l! ""'jl+), the smooth coni/dancer C is transmitted through the inverter oscillator A1 of the inverter circuit A.
8 is charged, and at the same time, the smoothing capacitor C1 is charged via the inverter oscillation section A. On the other hand, when the voltage VF of the AC power supply E is lli (L@ ~
ts, ja to t6), the current Is does not flow from the AC power supply E to the rectifier circuit B, and the charge in the smoothing capacitor C1 passes through the diode D to the inverter oscillation unit A,
Furthermore, the charge in the smoothing capacitor C2 is discharged to the inverter oscillation section A via the diode D1.

(Example 2) FIG. 3 shows a second example of the present invention. In this second embodiment, in parallel with the diode D, a diode D0 of opposite polarity, a capacitor C0, and a resistor R0 are connected.
A series circuit with a parallel circuit is connected to form a switch SW that is turned on when the power is turned on. When the power switch S is turned on, a current flows from the power supply E through the loops C1 → D0 → C0 → C1 → E, and the capacitor C0 and smoothing capacitor C,,C,
is charged. After that, the inverter oscillator A, (
The voltage Vct) across the smoothing capacitor C8+(the voltage VD across the diode D1) is applied, and the inverter oscillation unit A starts operating with the voltage VD1+Vct applied. Therefore, when the power switch S is turned on, the same effect as in the eleventh embodiment can be obtained, and this circuit configuration is also effective as a countermeasure against lightning surges.

(Embodiment 3) FIG. 4 shows a third embodiment of the present invention. In this third embodiment, a tie switch is connected in parallel with the diode D1 to turn off the transistor Q0 when the power is turned on. , ChiS
W, and at the same time as the power switch S is turned on, the rectified output is routed from Ro-4C0→Q0→C3.
, a base current flows through transistor Q0, turning on transistor Q0, and charging smoothing capacitors C1 and C8. Smoothing capacitor C+, after charging Ct, the base current is cut by capacitor C0 and transistor Q. It will be turned off. Even with such a switch configuration, effects similar to those described above can be obtained.

〔Effect of the invention〕

The present invention is constructed as described above, in which a rectifier circuit is connected to an AC power source, and a circuit in which first and second smoothing capacitors are connected in series to both ends of a diode is connected between the DC output terminals of the rectifier circuit. , the diode is connected so that the rectifying direction is opposite to the rectifying direction of the rectifier circuit, a switch is provided in parallel with the diode, and when the power switch is turned on, the first and second smoothing capacitors are charged via the switch. death,
By turning off this switch after it is fully charged,
It is possible to prevent overvoltage from being applied to the inverter circuit, and therefore, there is an effect that a transistor having a lower breakdown voltage than the conventional transistor can be used. Note that the inverter oscillation section may simply be a load circuit, and the same effect can be obtained as long as the switch connected in parallel to the diode has a function of turning off after a certain period of time after the power is turned on. It will be done.

[Brief explanation of the drawing]

Figure 1 shows the features of the present invention! 1 is a circuit diagram of the first embodiment, FIG. 2 is an explanatory diagram of the same operation as above, FIG. 3 is a partially omitted circuit diagram of the second embodiment of the present invention, and FIG. 4 is a third embodiment of the present invention. FIG. 5 is a circuit diagram of a conventional example, in which E is an AC power supply, B is a rectifier circuit, and c is a partially omitted circuit diagram. , CI are first and second smoothing capacitors, Dl is a diode, SW is a switch, and Al + A are first and second inverter oscillation units provided as first and second load units, respectively. .

Claims (1)

[Claims] (1) A rectifier circuit is connected to an AC power source, and a circuit in which first and second smoothing capacitors are connected in series to both ends of a diode is connected between the DC output terminals of the rectifier circuit so that the rectifying direction of the diode is in the rectifier circuit. Connect the diode so that it is in the opposite direction to the rectifying direction, and connect the switch in parallel with the diode above.
A first load section is connected in parallel to a series circuit of the parallel circuit of these diodes and switches and a first smoothing capacitor, and a second load is connected to a series circuit of the above parallel circuit and a second smoothing capacitor. 1. A power supply device, characterized in that the switches are connected in parallel, and the switch is turned on only for a predetermined time when the power is turned on.