JP2859022B2 - Power control system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power supply control system, and more particularly to a power supply control system having a plurality of switching power supply circuits connected in parallel and supplying power to a common load.

[0002]

2. Description of the Related Art Conventionally, a power supply control system of this type includes a master circuit for transmitting an error signal of the output voltage of the system with respect to a predetermined reference voltage, and a switching circuit according to the error signal from the master circuit and the output current of its own circuit. And a slave circuit for transmitting a pulse. And
The switching pulse from each slave circuit is applied to the corresponding switching transistor, respectively,
A stabilized switching regulator was configured.

The conventional system will be described with reference to FIG. FIG. 5 is a block diagram showing a configuration of a main part of a conventional power supply control system.

Referring to FIG. 1, a master circuit 101 in a conventional system includes a reference voltage circuit 104 for generating a reference voltage.
And an error amplifying circuit 103 for transmitting an error signal of the system output voltage with respect to the reference voltage from the circuit 104; and controlling the output of the error amplifying circuit 103 in response to an external ON / OFF command. And an on / off circuit 126 for performing on / off.

On the other hand, a slave circuit 105 in the conventional system has a current feedback circuit 106 which receives an output current of its own circuit as an input and converts it into a voltage corresponding to the current value, and a saw-tooth wave generating circuit which generates a predetermined saw-tooth signal. A signal obtained by wired-ORing the error signal from the master circuit 101 and the output of the current feedback circuit 106 into a sawtooth wave generation circuit 107
And a comparator 108 for comparing the signal with a sawtooth signal.

[0006] The slave circuit 115 is a slave circuit.
It includes a current feedback circuit 116, a sawtooth wave generation circuit 117, and a comparator 118 having the same functions as those of the circuit 105.

Although the illustrated system has two slave circuits 105 and 115, even when three or more slave circuits are provided, each slave circuit has the same configuration.

Here, the on / off circuit 126 includes a switching transistor which performs an on / off operation in accordance with an input voltage to the on / off input terminal 125, and a capacitor which is charged by the on operation of the transistor and discharged by the off operation. The charge voltage of this capacitor is wired-ORed with the voltage of the output voltage detection terminal 102 and applied to the non-inverting input terminal of the error amplifier 103.

In such a configuration, in the conventional power supply control system, when the output voltage of the switching regulator according to the present system is input to the output voltage detection terminal 102 in the master circuit 101, it is input to the non-inverting input terminal of the error amplifier circuit 103. Is done. At the same time, an on / off signal is input from the on / off terminal 125 to the on / off circuit 126, and the output of the on / off circuit 126 is input to the error amplifier 103.

The reference voltage circuit 104 applies a reference voltage to the inverting terminal of the error amplifier circuit 103.

The error signal from the error amplification circuit 103 is input to a plurality of slave circuits 105 and 115. On the other hand, the output current of each slave circuit is input to current detection terminals 113 and 123, respectively, and is converted into a voltage in current feedback circuits 106 and 116.

The converted voltage is combined with the voltage of the error signal from the error amplifier 103, and is input to the non-inverting input terminals of the comparators 108 and 118. Comparators 108 and 118
The sawtooth wave generating circuits 107 and 117 receive the sawtooth wave from the inverting input terminals, and the outputs of the comparators 108 and 118 are output from the on-pulse output terminals 114 and 124 to operate the pulse width modulation type switching power supply circuit. That is, the output of each comparator is applied to a switching transistor (not shown).

Here, in order to turn off this conventional system, an off signal is applied to an on / off input terminal 125, and an error amplifier 103 outputs the output signal as if it were an output voltage detection terminal 102.
A high voltage is applied from the on / off circuit 126 so that the output voltage detected by the above becomes high. As a result, the error amplification circuit 103 determines that the output voltage is higher than the reference voltage generated by the reference voltage circuit 104, and lowers the voltage value of the error signal to lower the output voltage. Then, the slave circuits 105 and 115
The non-inverting input terminal voltage of each of the comparators 108 and 118 becomes lower than the sawtooth voltage of the inverting input terminal. As a result, no pulses are output from the on-pulse output terminals 114 and 124, which are the outputs of the comparators 108 and 118, and the operation of the switching regulator according to the present system is stopped.

Further, in order to operate the switching regulator according to the present system, an on / off input terminal 125 is required.
The high voltage applied to the error amplifier 103 from the on / off circuit 126 is gradually reduced. Then, the output of the error amplifier 103 gradually increases as the voltage of the reference voltage circuit 104 approaches,
, 118 also gradually increase and gradually exceed the output voltages of the sawtooth wave generating circuits 107, 117. As a result, the pulse widths of the output on-pulses of the on-pulse output terminals 114 and 124, which are the outputs of the comparators 108 and 118, gradually increase, and the output voltage of the switching regulator according to the present system gradually increases.

Thereafter, when the output voltage input to the output voltage detection terminal 102 becomes equal to the reference voltage from the reference voltage circuit 104, the output of the on / off circuit 126 becomes invalid and the output voltage is stabilized.

In the conventional system described above, the efficiency of the system is sufficiently good when the load is large with respect to the rated output capacity, but the efficiency becomes very poor when the load is small. For example, when power is supplied to a memory device, the input power supply of the system is usually a commercial power supply and the load is large in normal times. However, in the event of a power failure, when the input power is switched to the battery and the memory device is also in the standby state and the load is reduced, the efficiency is reduced and the operation time on the battery is reduced.

[0017]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional drawbacks, and an object of the present invention is to provide a power supply control system which does not deteriorate even when the load is small.

[0018]

A power supply control system according to the present invention comprises: an error signal generating circuit for generating a common error signal according to an error of a voltage supplied to a common load with respect to a predetermined reference voltage; A switching circuit for supplying power to the common load in response to the error signal and an external command .
And a plurality of switching power supply circuits including a control circuit for controlling the circuit to be active / inactive in response to integrating means for gradually increasing and decreasing the voltage value .

[0019]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a main part of a first embodiment of a power supply control system according to the present invention. In the system of the present embodiment, the slave circuit 5 connected in parallel
And 15 have a function of performing on / off control individually as well as a function of performing on / off control collectively. That is, each slave circuit has a function of controlling its own circuit to active / inactive in response to an external command.

In the figure, the system of the present embodiment comprises an on / off circuit 26, an error amplifier circuit 3, and a reference voltage circuit 4.
The master circuit 1 includes The configuration and operation of the master circuit 1 are the same as those of the conventional one (FIG. 5), and an error signal is commonly input to each slave circuit.

The slave circuits 5 and 15 in the system of the present embodiment have current feedback circuits 6 and 16, saw-tooth wave generating circuits 7 and 17, and comparators 8 and 18. The operation of these circuits in each slave circuit is the same as that of the conventional one (FIG. 5).

However, an on / off terminal 9 (or 19), an integrating circuit 10 (or 20), a comparator 11 (or 21), and an AND circuit 12 (or 22) are newly provided in the slave circuit of the present system. I have. The on / off control of each slave circuit is individually performed by these circuits and the like.

Here, the on / off terminals 9 and 19 are terminals for inputting an on / off signal from the outside, and the signals are input to the integration circuits 10 and 20 and smoothed. The signal after the smoothing is input to the comparators 11 and 21 and is compared with the sawtooth wave. Then, the comparison result is ANDed with the outputs of the comparators 8 and 18 in the AND circuits 12 and 22. The reason why the smoothing is performed by the integration circuit is to prevent a malfunction of the circuit due to an inrush current at the time of on / off.

The outputs of the AND circuits 12 and 22 are applied to switching transistors (not shown) via on-pulse output terminals 14 and 24. The switching transistor converts a DC input on the primary side of a transformer (not shown) into AC and transmits the AC to the secondary side. On the secondary side of the transformer, a rectifier diode and a smoothing capacitor are used to make DC. That is, a slave circuit, these transistors (not shown),
A well-known switching power supply circuit is composed of a transformer, a diode, a capacitor, and the like.

Further, as described above, the slave circuits are connected in parallel and supply power to a common load. Therefore, the output voltages of the two slave circuits are compared with a predetermined reference voltage in the master circuit, and not only the control is performed so as to cancel the error, but also in the switching power supply circuit of each slave circuit, the output current is detected by the current detection. It is fed back to the terminal and the load is shared.

In this configuration, when the output voltage of the switching regulator according to the present system is input to the output voltage detection terminal 2 in the master circuit 1, it is input to the non-inverting input terminal of the error amplifier circuit 3. The reference voltage output of the reference voltage circuit 4 is input to the inverting input terminal of the error amplifier circuit 3. The error amplifier circuit 3 operates to increase the output voltage when the output voltage of the present system falls below the reference voltage, and to decrease the output voltage when the output voltage rises.

The switching on / off of the entire switching regulator according to the present system is performed by applying an on / off signal to an on / off input terminal 25. That is, at the time of OFF, the ON / OFF circuit 26 applies a voltage higher than the voltage applied to the non-inverting input terminal of the error amplifier circuit 3 to the non-inverting input terminal of the error amplifier circuit 3, and the voltage of the switching regulator becomes too high. Make it. This allows
The output voltage of the error amplifier circuit 3 is turned off as in the conventional case.

When the switch is on, the voltage of the on / off circuit 26 is gradually decreased, and the output of the switching regulator is gradually increased. When the voltage becomes equal to the reference voltage, the voltage of the on / off circuit 26 becomes invalid, and the output of the error amplification circuit 3 becomes a constant voltage.

The output of the error amplifier 3 is input to slave circuits 5 and 15 which are control units of a plurality of switching power supply circuits, respectively, and the output current of each switching power supply circuit is input to each of the current detection terminals 13 and 23. You.

In the current feedback circuits 6 and 16, when the output current is large, the voltage value is reduced, and when the output current is small, the voltage value is increased and converted to a voltage which becomes constant at the rated current. The output voltage of the current feedback circuit is combined with the voltage of the output of the error amplifier circuit 3, and is used as a control voltage by the comparator 8,
18 are respectively input to the non-inverting terminals.

The sawtooth waves from the sawtooth wave generating circuits 7 and 17 are input to the inverting terminals of the comparators 8 and 18, respectively.
As shown in FIG. 2, the comparators 8 and 18 output pulses only when the control voltage exceeds the voltage value of the sawtooth wave. Therefore, the pulse width of the output of each of the comparators 8 and 18 becomes narrow when the output voltage is higher than the reference voltage, and becomes wide when the output voltage is low.

Here, in the present embodiment, the slave circuits 5, 15 which are the control units of the respective switching power supply circuits are used.
Are provided with on / off terminals 9 and 19. The on / off signal input to this terminal is integrated and smoothed by the integration circuits 10 and 20. That is, when the output is off, the outputs of the integrating circuits 10 and 20 (the non-inverting inputs of the comparators 11 and 21) gradually decrease as shown in FIG. To narrow. When the voltage becomes lower than the sawtooth wave input to the inverting input terminals of the comparators 11 and 21, the outputs of the comparators 11 and 21 become "L". As a result, no on-pulse is output.

When it is on, the outputs of the integrating circuits 10 and 20 (comparators 11 and 21) as shown in FIG.
Non-inverting input) gradually rises, and the comparators 11 and 12
The output of No. 1 has a gradually widening pulse width. When the voltage becomes higher than the sawtooth wave input to the inverting input terminals of the comparators 11 and 21, the outputs of the comparators 11 and 21 become "H". As a result, an ON pulse is output.

Both outputs of the comparators 8 and 11 are ANDed by the AND circuit 12, and both outputs of the comparators 18 and 21 are ANDed by the AND circuit 22.
These are output to the ON pulse output terminals 14 and 24, respectively, as ON pulses of transistors (not shown) of the switching power supply circuit.

Therefore, when both of the on / off terminals 9 and 19 are on, all the switching power supply circuits are operating. However, for example, when the on / off terminal 9 is turned off, the pulse width of the on pulse from the slave circuit 5 gradually narrows and stops, so that the switching power supply circuit of the slave circuit 5 also gradually decreases its output current. Stop. As a result, only the switching power supply circuit of the slave circuit 15 operates, and a constant voltage and current are continuously supplied to a load (not shown) while the stoppage of the slave circuit 5 is maintained.

When the on / off terminal 9 is turned on from that state, the pulse width of the on pulse of the slave circuit 5 gradually increases from the stop state and becomes a constant pulse width. As a result, the switching power supply circuit of the slave circuit 5 also gradually supplies the output current from the stopped state, and the output current of the switching power supply circuit of the slave circuit 15 gradually decreases. Then, the switching power supplies by both slave circuits supply the same output current.

FIG. 3 is a block diagram showing a configuration of a main part of a second embodiment of the power supply control system according to the present invention, and the same parts as those in FIG. 1 are denoted by the same reference numerals. The system of this embodiment also has a function of turning on / off the slave circuits 5 and 15 connected in parallel collectively as in the system of FIG. I have.

In the figure, the system of this embodiment is the same as that of FIG.
In this configuration, one of the comparators and the AND circuit are omitted from each slave circuit.

That is, in the present embodiment, the error signal from the error amplifier circuit, the output of the current feedback circuit, and the output of the integration circuit are wired-ORed and input to the comparator in each slave circuit. .

Also in the present embodiment, the slave circuits 5 and 5 which are the respective control units of the respective switching power supply circuits are provided.
15 are provided with on / off terminals 9 and 19. The on / off signal input to this terminal is integrated and smoothed by the integration circuits 10 and 20. That is, when turned off, the output voltages of the integration circuits 10 and 20 gradually decrease as shown in FIG. 4 and become lower than the sawtooth wave input to the inverting input terminals of the comparators 8 and 18. Go. As a result, the output pulse widths of the comparators 8 and 18 gradually become narrower and eventually become "L", and the on-pulse output terminal 1
No on-pulse of the switching power supply circuit is output from 4, 24. As a result, power is supplied from only one switching power supply circuit by one slave circuit to a load (not shown).

When turned on, as shown in FIG. 4, the output voltages of the integrating circuits 10 and 20 gradually increase, and the voltage becomes higher than the sawtooth wave input to the inverting input terminals of the comparators 8 and 18. When it becomes high, the output of the comparators 8 and 18 gradually increases in pulse width from "L" and becomes a constant pulse width. Thus, power is supplied from the switching power supply circuit by the two slave circuits to the load (not shown).

In FIG. 4, the control voltage is a voltage obtained by wired-ORing the error signal from the error amplifier 3 and the output of the current feedback circuit.

In the first and second embodiments described above, the case where two slave circuits are provided has been described. However, it is apparent that the present invention can be similarly applied to the case where three or more slave circuits are provided. In that case, each slave circuit must have a similar configuration.

As for the method of inputting the ON signal or the OFF signal to the ON / OFF terminal, any one of a method of inputting an OFF signal in response to the occurrence of a power failure and the like besides a method of inputting by an operator's manual operation, and the like A method may be used.

[0046]

As described above, according to the present invention, not only the switching power supply circuits connected in parallel can be turned on / off collectively but also the switching power supply circuits can be turned on / off individually. By doing,
Even when the common load is smaller than the rated output capacity, there is an effect that the efficiency does not deteriorate if the common load is individually turned off.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a main part of a power supply control system according to a first embodiment of the present invention.

FIG. 2 is a time chart showing the operation of the system of FIG. 1;

FIG. 3 is a block diagram showing a configuration of a main part of a power supply control system according to a second embodiment of the present invention.

FIG. 4 is a time chart showing the operation of the system of FIG. 3;

FIG. 5 is a block diagram showing a configuration of a main part of a conventional power supply control system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Master circuit 2 Output voltage detection terminal 3 Error amplifier circuit 4 Reference voltage circuit 5, 15 Slave circuit 6, 16 Current feedback circuit 7, 17 Saw wave generation circuit 8, 11, 18, 21 Comparator 9, 19 On / off terminal 10, 20 Integrator circuit 12, 22 AND circuit 13, 23 Current detection terminal 14, 24 ON pulse output terminal

Claims (4)

(57) [Claims] 1. An error signal generating circuit for generating a common error signal in accordance with an error of a voltage supplied to a common load with respect to a predetermined reference voltage; and an output current of its own circuit and the common load in accordance with the common error signal. to the switching circuit and the external command power supplied to
A power supply control system, comprising: a plurality of switching power supply circuits including a control circuit that controls an own circuit to be active / inactive in response to integrating means for gradually increasing and decreasing the voltage value . 2. The power supply control system according to claim 1, wherein the control circuit controls on / off of a switching pulse to a transistor in response to the external command. Wherein said external command power supply control system according to claim 1 or 2, characterized in that a signal which is manually input from the outside. Wherein said power supply control system according to claim 1 or 2, wherein the external command is a signal that is input in response to the power failure.