JPS586048A - Operating and spare power source switching control circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power supply circuit, and more particularly to a control circuit for switching between active and standby power supplies to improve the reliability of a power supply device.

Conventionally, this type of switching circuit for active and standby power sources has been constructed as shown in FIG. In this drawing, PUL
is the current DC stabilized power supply circuit, PO2 is the standby DC stabilized power supply circuit, 1 and 11 are the unregulated DC power supplies, 2 and 12 are the main control circuits, 3 and 13 are the error amplifier circuits, and 4 and 14 are the reference In the voltage generating circuit, 9 is a load, Dl and Dll are reverse current blocking diodes. , In this circuit, in order to increase the accuracy of output voltage detection, all voltages are detected between the terminals of load 9, and settings are made so that the working unit PUI can obtain a slightly higher output voltage than the standby unit PU2. )
Therefore, the diode D1 is normally in a forward conducting state, and constant voltage controlled direct current is supplied from the current machine PUI to the load 9.

In this state, the detection voltage given to the error amplification circuit 13 of the standby unit PU2 is VL, which is a slightly higher voltage (than the reference voltage Vrt given to the error amplification circuit 13), so the main control The circuit 12 always has an output voltage V
In a steady state, the value of the output voltage Vcz is approximately zero volts.

If the active PUI stops due to a failure in this state, the standby dPU2 must rise from an output voltage of zero volts and supply DC to the load 9 of the active PUI. Therefore, there are disadvantages that large transient voltage fluctuations occur when switching, and in the case of intermittent output drops of the active unit PUI, DC is supplied from the active unit PUI again after recovery. It is necessary to set the output voltage somewhat low, and when used stably at a low output voltage, there is a drawback that it is difficult to satisfy a predetermined voltage fluctuation rate.

The object of the present invention is to ensure that even if the output voltages of the active and standby units are set to exactly the same value, the output voltage rise time of the standby unit is slower than that of the standby unit, and that the output voltage of the standby unit is By switching the output voltage detection point so that the voltage across the blocking diode stays at zero volts, that is, the same voltage as the load voltage, the above drawbacks are eliminated and a highly stable and highly accurate DC voltage can be used for all current applications. The purpose of the present invention is to provide a complete control circuit for switching between active and standby power sources, which enables output from both the machine and the standby machine.

Describing the structure of the present invention, the present invention provides a current/standby power supply switching control circuit in which the outputs of two DC stabilized power supply circuits PUI and PU2 are connected in parallel to a load via diodes DI and Dll, respectively. The diode D1 input terminal of one PU1 of the DC stabilized power supply circuit of the
If the output voltage of the diode Dll of the other PU2 is higher than the output voltage of the diode Dll of the other PU2, the output voltage of the diode Dll of the other PU2 is set to one side. P of
If the voltage of the diode D1 of the UI is higher than that of the UI, the other PU2' is operated as a backup power source, and the switch circuit stabilizes the DC of the two units by supplying the output voltage of the diode D11 as an output voltage detection signal. This is a current and standby power supply switching control circuit with all the features added to the power supply circuit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS All embodiments of the present invention will be described below with reference to all drawings.

FIG. 2 shows a circuit diagram of an embodiment of the invention. In FIG. 2, the uninvented current/standby power supply switching control circuit includes an unregulated DC power supply 1, a main control circuit 2, an error amplification circuit 3, a reference voltage generation circuit 4, a power supply output terminal 6, Detection signal input terminal 7, common return terminal 8, and overvoltage detection short circuit 5
A known DC stabilized power supply circuit PUI consisting of a non-stabilized DC power supply 11, a main control circuit 12, and an error amplification circuit 13.
, a known DC stabilized power supply circuit PU2 consisting of a reference voltage generation circuit 14, a power supply output terminal 16, a detection signal input terminal 17, a common retrace terminal 18, and an overvoltage detection short circuit 15, and a power supply output terminal. A diode D whose anodes are connected to 6 and 16, respectively, and whose cathodes are connected to each other.
1 and Dll, and a load 9 connected to the cathodes of diodes D1 and Dll and the common return terminals 8 and 18, respectively.
, a PNP transistor Ql whose emitter is connected to the anode of the diode D1, and whose collector is connected to the detection signal input terminal 7, and a resistor R2 connected between the collector of the PNP transistor Ql and the cathode of the diode D1,
The output terminal is connected to the base of the transistor Q1 (PNP) through the resistor ratio 1, and the positive input terminal is connected to the diode D.
The negative input terminal is the diode Dl on the cathode of 1.
A comparator Z1 connected to the anode of the resistor I (14?), a PNP transistor Qll whose emitter is connected to the anode of the diode Dll, and a collector connected to the detection signal input terminal 17, respectively, and a PNP transistor Q1.
A resistor R12 is connected between the collector of transistor Qll and the cathode of diode Dll, and a resistor R12 is connected to the base of a transistor Qll whose output terminal is PNP. To,
a comparator Zll whose negative input terminal is connected to the anode of the diode Dll through a resistor h4'2;
A resistor R3 connected between the output of the comparator Zl and the negative side of the comparator Zl 1 and a resistor A13 connected between both the comparator Zll and the negative side of the comparator Zl ~ in parallel with the load 9 The capacitor C1 is connected to the capacitor C1.

In the circuit shown in Figure 8g2, the voltages after passing through the diodes of the known DC stabilization power supply circuits PUI and PO2 are set in advance to approximately the same voltage (■3), and the rise time of the output voltage of the DC stabilization power supply circuit PUI is is the rise time of the output voltage of the DC stabilized power supply circuit PU2), the diode D1 becomes forward biased first, so that the potential on the negative side of the comparator Zll is not further away from the positive side input, and the transistor Qll is turned on. Meanwhile, the DC stabilized power supply circuit PU2 operates so that the potential of the anode of the diode Dll is the same as the potential of the cathode, and therefore cannot supply DC to the load 9. - The negative input of the comparator Zl is pulled to a low level through the entire resistor R13 by the output of the comparator 11, so R14'
If properly selected, the potential of the cathode of the diode D1 will be slightly lower than the positive input, and therefore the transistor Ql is off, so the DC stabilized power supply circuit PUI will set the potential of the cathode of the diode D1 to v3.
Therefore, it supplies direct current to the load 9 and becomes a working machine.

Next, if the current machine is unable to fully supply DC to the load 9 due to some kind of failure, or if the overvoltage protection short circuit 5 is activated, the potential at the anode of the diode D1 will drop rapidly, but the potential at the cathode of the diode D1 will drop rapidly. The potential decreases only gradually due to the accumulated charge of conde/scl.

Therefore, the negative side potential of comparator Z11 is
When the voltage is lower than the positive input potential, the output of Zll becomes high level, the transistor Qll is turned off, and the DC stabilizing power supply circuit PU2 starts operating so that the potential of the cathode of the diode Dll becomes V3. And DC to load 9? 1J (provide.

In this way, capacitor CI, resistor approximately 1゜L3
．． ) and 4.1 and 11. )Li2. ) By selecting an appropriate value for 14, it is possible to minimize the transient voltage fluctuation when switching from the active unit to the standby unit for the load 9, and to minimize the fluctuation in the steady voltage due to switching. It is possible to make it smaller.

-Also, the circuit in Figure 2 is such that even if the blade supply capacity of the current machine is restored after the current machine is unable to supply output, and the current machine's blade supply capacity is restored after switching to standby machine operation in the sequence described above, It has the feature of excellent maintainability because it does not switch to operation.

As described above, the circuit of the present invention having a four-layer structure has the effect of greatly reducing transient fluctuations and steady-state voltage fluctuations with respect to the load during switching between working and standby switching.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional example, and FIG. 2 is a circuit diagram showing one embodiment of the present invention. Note that the symbols used in the drawings indicate the following. PUI, PO2...DC stabilized power supply circuit, 1゜11...Unregulated DC power supply, 2,12-...
...Main control circuit, 3.13...Error amplification circuit,
4.14...Reference voltage generation njt path, 5.15
・-・・・Overvoltage detection short circuit, 6, 16...
・-・Power output terminal, 7.17...Detection signal long sword terminal, 8.18...Common return terminal, 9...
...Load, R1-4. Rx1-14...Resistor, comparator for Zl, Zll..., Ql, Qll
...Transistor, DI, Dll...
1) Haru Denshi-ichi-shi

Claims (1)

[Claims] In a current/standby power supply switching control circuit in which the outputs of two DC stabilized power supply circuits PUI and PU2 are connected in parallel to the load via diodes DI and Dll'i, respectively, one of the two DC stabilized power supply circuits PUI If the diode D1 input terminal of the other PO2 is higher than the diode Dll output voltage of the other PO2, it is operated as the one PUlt-current power supply, and the diode DI output voltage is supplied as an output voltage detection signal, and the other PO2 If the diode Dll output voltage of one PUI is higher than that of the diode D1 input terminal of one PUI, the switch circuit operates as a backup power source of the other PU2ffi and supplies the diode Dll output voltage as a tube output voltage detection signal. A control circuit for switching between active and standby power sources, characterized in that it is configured by being added to each DC stabilized power supply port 'wl' of the unit.