JPS61273171A - Multioutput dc power source - Google Patents

Abstract

PURPOSE:To externally apply a stable output voltage by altering the pulse width of a pulse signal for intermittently interrupting a switching element in response to the output voltage of a DC power source. CONSTITUTION:A pulse-width control type multioutput DC power source has an input smoothing circuit 2, a switching element 3, a voltage converting transformer 4, rectifiers 5, 10 of an output circuit, smoothing circuits 6, 11, and voltage stabilizers 12, 15 to control the pulse width of the element 3 through a pulse width modulator 7, an oscillator 8 and a drive circuit 9. In this case, an input voltage detector 21 is provided to detect the voltage of the primary voltage source 1 and to apply the detected voltage 121 to the modulator 7. Thus, the modulator 7 varies the pulse width proportionally to the voltage 121 to drive the element 3 through the drive circuit 9 by the pulse signal 107.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pulse width controlled multi-output DC power supply used as a DC power supply for various electronic devices such as microwave communication equipment.

(Prior Art) A DC voltage obtained by rectifying a battery or a commercial power source is used as a primary voltage source for microwave communication equipment. When this primary voltage source fluctuates greatly, it can be used as a voltage stabilization circuit to supply stable DC voltage to microwave communication equipment.It operates over a wide input voltage range and is an efficient pulse width control type multi-output DC current converter. A power source is used. FIG. 2 is a block diagram showing a circuit example of a conventional pulse width controlled multi-output DC power supply. In the figure, 1 is a primary voltage source, 2 is an input smoothing circuit,
3 is a switching element, 4 is a voltage conversion truss, 5 is a rectifier circuit of the first output circuit, 6 is a smoothing circuit of the first output circuit, 7 is a pulse width modulation circuit, 8 is an oscillation circuit, and 9 is a A drive circuit, 10 is a rectifier circuit of the second output circuit, 11 is a smoothing circuit of the second output circuit, 12 is a voltage stabilization circuit of the second output circuit, 13-1 and 13-2 are the first outputs. Output terminals 14-1 and 14-2 of the circuit are output terminals of a second output circuit, and 20 is an output voltage detection circuit. The operation will be explained below.

When the switching element 3 is turned on by the pulse signal 109 output from the drive circuit 9, the secondary winding n of the voltage conversion transformer 4 has a winding ratio equal to that of the primary winding n. A corresponding voltage is generated and supplied to the outside through the rectifier circuit 5 and the smoothing circuit 6 from the output terminals 13-1 and 13-2.

The output voltage detection circuit 20 has output terminals 13-1 and 13-2.
The difference voltage between the voltage and the set output voltage inside the output voltage detection circuit 20 is detected. The pulse width modulation circuit 7 changes the pulse width of the output pulse signal 107 according to the differential voltage 120. The drive circuit 9 amplifies the power of the pulse signal 107 and turns the switching element 3 on and off. The ON/OFF ratio of the switching element 3 changes depending on the pulse width of the pulse signal 109.

For example, the voltage of the primary voltage source 1 increases, and the output terminal 13-
1. When the voltage of 13-2 rises, the output voltage detection circuit 2
Due to the voltage detected by 0, the pulse width of the output 107 of the pulse width modulation circuit 7 is narrowed, and the ON time of the switching element 3 is shortened via the drive circuit 9. When the ON time of the switching cable 3 becomes shorter, the output voltage after rectification and smoothing also decreases and becomes approximately equal to the set output voltage, thereby stabilizing the output voltage. Further, the voltage of the second output winding n, is also adjusted by the rectifier circuit lO1, the smoothing circuit 11. After passing through the voltage stabilizing circuit 12, it is sent out as a stabilized voltage to the outside from the output terminals 14-1 and 14-2.

(Problems to be Solved by the Invention) In the smoothing circuit 6 of the first output circuit described above, a choke input circuit is generally used in consideration of ripple compression characteristics. Therefore, output terminal 13-1.13-
When the output current of No. 2 decreases and the current flowing through the choke coil of the choke input circuit becomes discontinuous, the ripple voltage increases rapidly and the voltage after smoothing increases. Therefore, when the output current of the output terminal 13-1.13-2 decreases and the output voltage increases, the ON time of the switching element 3 becomes shorter due to the voltage stabilization loop described above, and the output terminal 13-1.13
-2 voltage is stabilized. However, since the voltage of the second output winding n of the voltage conversion transformer 4 decreases, the voltage of the rectifier circuit 10. Smoothing circuit 11 and voltage stabilization circuit 12
There is a problem in that the voltage at the output terminal 14-1.14-2 obtained through the process decreases below a predetermined value, and the normal voltage can only be sent out from the output terminal 14-1.14-2. Ta.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a multi-output DC power supply in which fluctuations in the output current of one output circuit do not easily affect the output voltages of other output circuits.

(Means for Solving the Problems) Means provided by the present invention to solve the above-mentioned problems is a transformer! The secondary winding and a DC power supply circuit are connected via a switching cable, and the output of the secondary side of the transformer is rectified to output a plurality of DC powers, and a pulse signal is generated to intermittent the switching element. A multi-output DC power supply that stabilizes the voltage of the DC power by changing the pulse width, wherein the circuit that generates the pulse signal changes the pulse width according to the output voltage of the DC power supply circuit. 0 (Example) Next, the present invention will be described in detail with reference to Examples.

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, 15 is a voltage stabilizing circuit of the first output circuit;
1 is an input voltage detection circuit. An example of its operation is shown below.

The voltage of the primary voltage source 1 is guided to the input voltage detection circuit 21 via the input smoothing circuit 2 and detected, and the detected voltage 121
is sent to the pulse width modulation circuit 7. The pulse width modulation circuit 7 outputs a pulse signal 107 whose pulse width is changed in proportion to the detected voltage 121. The drive circuit 9 turns on and off the switching element 3 using a pulse signal 109 obtained by power amplifying the pulse signal 107. O of switching cable 3
N.

The 0FIF ratio is controlled by the pulse width of pulse signal 109.

For example, when the input voltage becomes high, the input voltage detection circuit 21
The detection voltage changes, and in accordance with the change, the output pulse width of the pulse width modulation circuit 7 becomes narrower, and the ON time of the switching element 3 becomes shorter via the drive circuit 9. When the ON time of the switching element 3 becomes shorter, the voltage conversion transformer 402
Next winding nl,.

After the voltage generated at point A and point B is rectified by the rectifier circuit 5.10 and smoothed by the smoothing circuits 6 and 11, the voltage at point A and point B also decreases and becomes equal to the set voltage. That is, the voltages at point A and point B are stabilized to a constant value in response to fluctuations in input voltage.

The output current changes due to fluctuations in the external load connected to the output terminals 13-1.13-2.14-1.14-2, but the output voltage is stabilized against this change in output current. , voltage stabilization circuit 12.16 is activated.

As explained above, in the multi-output DC power supply of this embodiment, the circuit that stabilizes the output voltage against fluctuations in input voltage and the circuit that stabilizes the output voltage against fluctuations in output current are separated, and the latter circuit is It is provided for each output circuit. In the conventional multi-output DC power supply shown in FIG. 2, the output voltage of the second output circuit fluctuates due to fluctuations in the output current of the first output circuit, but in this embodiment with the above-mentioned configuration, both output circuits have no influence on each other. Since they do not match each other, a stable output voltage can be sent to the outside. Furthermore, although this embodiment is an example in which two DC powers are output, the same effect can be obtained with a power source that outputs three or more powers according to the present invention.

In this example, the rectifier circuit, smoothing circuit, and voltage stabilizing circuit are divided into functional units, but complex functions such as a chopper set switching regulator (rectifying, smoothing,
The same effect can be expected even if a circuit with voltage stabilization (voltage stabilization) is used on the secondary side of the voltage conversion transformer 4.

(Effects of the Invention) As described above in detail, according to the present invention, a multi-output DC power supply can be provided in which fluctuations in the output current of one output circuit hardly affect the output voltages of other output circuits. Further, in the present invention, since there is no need to feed back the voltage of the output circuit to the input circuit, it is possible to enjoy the advantage that insulation between the input circuit and the output circuit is easy.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional multi-output DC power supply. 1...Primary voltage source, 2...Input smoothing circuit, 3...
Switching element, 4... Voltage conversion truss 7 truss, 5゜10... Rectifier circuit, 6, 11... Smoothing circuit, 7...
- Pulse width modulation circuit, 8... Oscillation circuit, 9... Drive circuit, 12.16... Voltage stabilization circuit, 21... Input voltage detection circuit, 13-1.13-2.14- 1.14
-2...Output terminal. Agent Patent Attorney Nobu Honjo Valve tube 1 diagram

Claims (1)

[Claims] The primary winding of the transformer and the DC power supply circuit are connected via a switching element, and the output of the secondary side of the transformer is rectified to output a plurality of DC powers, and the switching element is turned on and off. A multi-output DC power supply that stabilizes the voltage of the DC power by changing the pulse width of a pulse signal, characterized in that the circuit that generates the pulse signal changes the pulse width according to the output voltage of the DC power supply circuit. Multi-output DC power supply.