JPH0258865B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multi-output switching power supply device suitable for power sources for communication equipment, computers, etc.

[Conventional technology]

As is well known, a multi-output switching power supply device converts a commercial frequency power source into DC at one end, operates a switching circuit with this DC, converts it back to AC, and uses the resulting AC voltage to oscillate and power the output transformer. It converts into multiple types of DC using a DC output circuit connected to multiple secondary windings.

In this multi-output switching power supply, when the DC output voltage fluctuates due to fluctuations in the input power supply and load, etc., the output voltage of the first DC output circuit of the multiple DC outputs is controlled to switch off the circuit such as the photocoupler. The switching time of the transistor of the switching circuit is controlled through the switching circuit to stabilize the output voltage of the first DC output circuit, and for the second, third, etc. The output voltage is stabilized using a chopper, seal regulator, etc.

[Problem that the invention seeks to solve]

As mentioned above, in order to stabilize each DC output voltage of a multi-output switching power supply, it is necessary to provide a voltage stabilization circuit using active elements such as transistors for each DC output, so the device is complicated. As a result, there is a problem that reliability is lowered and it is also economically disadvantageous.

[Means for solving problems]

The present invention provides a circuit that converts an AC output voltage from the output winding of an oscillation and output transformer into DC and feeds it back to a DC input power source that drives a switching circuit, and a circuit that converts the AC output voltage from the output winding of an oscillation and output transformer into DC and feeds it back to a DC input power source that drives a switching circuit, and a circuit that converts the amount of feedback of this circuit into DC output voltage. The system is equipped with a circuit that controls according to the

[Effect]

With the above configuration, when one voltage of the DC output circuit fluctuates, the voltage corresponding to the amount of fluctuation is fed back from the feedback circuit to the DC input power supply, and the input voltage is adjusted. This allows the output voltage of each DC output circuit to be constant.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings.

In the drawing, E is a commercial frequency power supply. This power supply E is rectified by a rectifier circuit 1, and the output DC power is supplied to a switching circuit 2. The output of this switching circuit 2 is converted into multiple DC outputs with different values by the DC output circuit 7, and then output to each load.
It is supplied to RL1, RL2, RL3, and RL4.

The positive side of the rectifier circuit 1 and the switching circuit 2
A diode 11 with the polarity shown in the figure is inserted in the electric path connecting the two to connect a feedback line to be described later.

The switching circuit 2 converts the direct current rectified by the rectifier circuit 1 into high frequency alternating current. 21 and 22 are starting resistances of switching transistors 23 and 24, respectively. The collector of the transistor 23 and the emitter of the transistor 24 are connected to the positive and negative bus lines P and N of the DC input power source via the choke input coil windings 25 and 26, respectively. 2
7 and 28 are coupling capacitors, and this capacitor 2
7 and 28 are connected in series between the positive and negative bus lines P and N. Reference numerals 3 and 4 indicate base drive circuits. These circuits 3 and 4 control the base currents of the transistors 23 and 24, keep the emitter-collector voltage constant, and prevent saturation of the transistors 23 and 24, allowing high-speed operation. It is something to be done.

5 is a saturable transformer for stabilizing the oscillation frequency; one end of the output winding 5253 of this transformer 5 is connected to the base drive circuits 3 and 4, and the other end is connected to the emitters of the transistors 23 and 24. Ru.
When the input winding 51 of the transformer 5 is connected to the control secondary winding 62 of the oscillation and output transformer 6,
A differentiation circuit 29 is inserted in one of the connection lines. The differentiating circuit 29 shapes the rectangular wave pulse current generated by the control secondary winding 62. The output side windings 52 and 53 are wound so that the voltage generated in the input side winding 51 has polarities opposite to each other.

One end of the input winding 61 of the oscillation and output transformer 6 is connected to a common connection point between the coupling capacitors 27 and 28, and the other end is connected to a common connection point between the emitter of the transistor 23 and the collector of the transistor 24. . The transistors 23 and 24 alternately open and close, and a pulse signal corresponding to this operation is supplied to the input winding 61. As a result, a rectangular wave pulse is generated in the control secondary winding 62. 6
3, 64, 65 and 66 are output side secondary windings wound corresponding to each load, each wound with the same polarity, and connected in series to the DC output circuit 7. Connected.

The DC output circuit 7 outputs each load RL1, RL2, RL
3. The rectifier circuit corresponding to RL4 is shown, with diodes 711 and 712, 721 and 722, and 7
31 and 732, 741 and 742, and smoothing capacitors 713, 723, 733, and 743.

Reference numeral 8 denotes a feedback amount control circuit, and this control circuit 8 controls a specific DC output voltage (in this embodiment, the load
It is composed of a circuit 81 that monitors the voltage (with respect to RL1) and detects the amount of variation thereof, a reactor 82 that controls the amount of feedback by this circuit 81, and a current control circuit 83 that controls the reactance of this reactor 82. . Voltage dividing resistor 811,
Reference numeral 812 is connected in series between the DC output terminals to which the load RL1 is connected, and obtains a partial voltage value therebetween. The difference between the obtained voltage and the standard voltage is detected by the shunt regulator 813 to control the current flowing through the resistor 832 of the current control circuit 83,
The collector current of transistor 831 is controlled.

Note that the series circuit of the resistor 814 and the capacitor 815 stabilizes the operation of the shunt regulator 813.

The reactor 82 is formed from a reactance control winding 821 and a reactor winding 822, and the reactance control winding 821 is formed by a transistor 831.
is inserted into the collector circuit of the transistor 83.
The conduction current changes depending on the collector current of 1,
The reactance of the reactor winding 822 is changed.

Reference numeral 9 denotes a feedback circuit, and this circuit 9 is composed of a feedback transformer 90 and diodes 94 and 95 for converting a feedback voltage into DC and feeding it back to both ends of diode 11 of the DC input power source of the switching circuit 2.
91 is an input winding of the transformer 90;
One end of the reactor winding 822 is connected to one end of the reactor winding 822, and the other end is connected to the output winding 65 of the transformer 6.

Note that the other end of the reactor winding 822 is the output side winding 6.
Connected to 6. As a result, the input winding 91 of the transformer 90 is applied with the voltage between all of the output windings 63, 63, 65, and 66, and the voltage of the reactor winding 822 added to this voltage. Ru. Reference numerals 92 and 93 are output windings of the transformer 90, and the alternating current voltage appearing at the windings 92 and 93 is rectified by diodes 94 and 95 and applied to both ends of the diode 11.

Next, the operation of the above embodiment will be explained.

The AC voltage of the commercial frequency power supply E is rectified by the rectifier circuit 1 and applied to the switching circuit 2 via the diode 11. The DC voltage is the blockage wire 2
5, transistor 23, input winding 6 of transformer 6
1. The circuit of the coupling capacitor 28 and the circuit of the coupling capacitor 27, the input winding 61, the transistor 24, and the blocking wire 26 are alternately connected and connected to the secondary output windings 63, 64, 65, and 66. Generates a square wave AC voltage. In this case, the base drive circuits 3 and 4, the saturable transformer 5, and the differentiator circuit 29 are configured to specify and maintain the oscillation frequency generated in the switching circuit 2, its waveform, and stable operation.

Secondary output windings 63, 64, 6 of the transformer 6
The voltage generated at 5 and 66 is the DC output circuit 7.
The circuit of diodes 711 and 712 and smoothing capacitor 713 provided in diode 7
21 and 722 and the smoothing capacitor 723 (hereinafter the same circuit), it is converted to DC, and the load
It is supplied to RL1 to RL4.

When DC voltage is being supplied to the loads RL1 to RL4 in this way, suppose that the DC input voltage or the load RL1 fluctuates, and the output terminal voltage of the first DC output circuit fluctuates, for example, rises above the specified voltage. The voltage across the terminals of the resistor 812 of the voltage divider circuit 81 increases,
The current in shunt regulator 813 and resistor 832 decreases. Therefore, the transistor 831
The collector current of decreases. As a result, the current in the reactance control winding 821 decreases, the magnetic flux of the iron core inserted into the reactor 82 decreases, and the reactance of the reactor winding 822 increases.

Therefore, the voltage applied to the input winding 91 of the feedback transformer 90 will be lower and the voltage applied to the output winding 9
Since the voltage appearing at 2 and 93 also becomes lower, the voltage fed back also becomes smaller. Therefore, the driving DC voltage of the switching circuit 2 decreases, and the output voltage of the oscillation and output transformer 6 decreases.
Due to this voltage drop, the output terminal voltage of the first DC output circuit is reduced and maintained at a specified value. still,
In contrast to the above, when the terminal voltage of the output circuit becomes low, the reverse operation is performed to increase the voltage and stabilize the voltage. In addition, although the second, third, and fourth output circuits are not provided with a voltage adjustment function, if the input/output windings of the oscillation and output transformer 6 are wound to a specified value, this implementation may be implemented. As shown in the example, when the duty of the secondary side AC output by an inverter system or the like is large, the voltage applied to these loads can also be made very small.

〔Effect of the invention〕

As described above, according to the present invention, the alternating current output generated in the output winding of the oscillation and output transformer is converted into direct current, this is fed back to the direct current input power source of the switching circuit, and this feedback amount is transferred to the first direct current output. Since it is controlled by the voltage value of the circuit, the voltages of a plurality of different DC outputs can be made constant.

Furthermore, according to the present invention, it is possible to achieve constant voltage with a minimum number of elements without using active elements such as multiple transistors, which not only simplifies the circuit configuration but also improves reliability. It also improves
It also has the advantage of being economically advantageous.

Further, according to the present invention, even if ripples are included in the output of the rectifier circuit of the commercial frequency power source, the influence on the output can be eliminated, so that the rectifier circuit of the commercial power source can be simplified. .

[Brief explanation of the drawing]

The drawing is a circuit diagram showing an embodiment of a multi-output switching power supply device according to the present invention. 1 is a rectifier circuit, 2 is a switching circuit, 3, 4
1 is a base drive circuit, 5 is a saturable transformer, 6 is an oscillation and output transformer, 7 is a DC output circuit, 8 is a feedback amount control circuit, and 9 is a feedback circuit.

Claims (1)

[Claims] 1 A switching circuit including an oscillation and output transformer is operated by a DC power source obtained by rectifying a commercial frequency power source, and the AC outputs obtained in multiple types of output windings of this transformer are rectified respectively to generate multiple outputs. A switching power supply device configured to obtain a DC output includes a circuit that converts the AC output generated in the output winding of the oscillation and output transformer into DC and feeds it back to the DC power supply of the switching circuit, and an input of the feedback circuit. and a feedback amount control circuit provided on the side, which detects a voltage fluctuation of one of the plurality of DC outputs, and controls the amount of feedback from the feedback circuit in accordance with the fluctuation of the DC output voltage. A multi-output switching power supply device featuring: