JPH033662A - Soft-start circuit of duplexing power supply - Google Patents

Abstract

PURPOSE:To eliminate the generation of overshoot by providing a load share circuit 40 with a soft-start circuit 50. CONSTITUTION:When a load-share signal is sent to an output stabilization circuit 20, a DC power supply PSI rises first, a switch SW is then turned ON, and the control signal of a start-stop control circuit enters a start mode a little later so that the DC/DC converter part 10 of a DC power supply PSII starts operation and the output voltage E2 thereof increases gradually. Because a soft-start circuit 50 deters the operation of a load-share circuit 40, an error amplifier circuit enters the steady state of the output voltage E2 at a set voltage in the DC power supply PSII single body. Thus, the load-share circuit 40 operates in such manner that the output voltage E2 increases to a voltage corresponding to output voltage E1, so as to enable eliminating the generation of overshoot.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a load sharing type duplex power supply device, and particularly to improvement of output voltage rise characteristics (occurring during online maintenance, for example).

<Prior Art> A power supply device is described, for example, in R Measurement and Control J, Vol. 27, No. 6 (June 1988), page 44. FIG. 4 is a block diagram of a conventional redundant power supply device. Here, power supplies PSI and II with the same configuration are connected in parallel,
A DC input voltage V jlt is applied, and a DC output voltage vg is supplied to the load. The source PSI inputs an input voltage VrrL and outputs a DC voltage of a predetermined voltage E1.
C/DC converter section 10, and a diode D that matches this DC output E1 with the DC output E2 of the other power supply PS■.
(matching circuit) and an output stabilizing circuit 20 that stabilizes the output voltage v. For example, the output stabilization circuit 20 sets the output voltage VlIIt to a predetermined reference voltage V ref
and a pulse width control circuit PWMC that sends a control signal in the direction of reducing this error signal.
It has TL.

In addition, in coordination with the other power supply, there is an output voltage detection circuit 30 that detects the DC output E1 and sends it to the power supply PS■, and a load control # signal to the pulse width control circuit PWMCTL based on this sent voltage. It has a load sharing circuit 40 for transmitting data. This load sharing is called an output voltage control type, in which the power supply PS with a higher output voltage follows the output voltage of the power supply PS with a lower output voltage, thereby supplying load power from the two power supplies. 6 <Problem to be solved by the invention> In such devices, one power source may be turned on from an off state during online maintenance work (equivalent to turning on the switch SW in the figure). ), 5th
The diagram shows that the power supply PSI is operating first, then the switch S
This shows a transient state in which W is turned on and power supply PS■ starts operating. In this case, since the load sharing circuit of the power supply PS2 is operating before the switch SW is turned on, the DC output E2 rises at the moment it is turned on, causing an overvoltage (overshoot) in the output voltage.

This poses a problem in that the overvoltage protection circuit may operate and the DC/DO converter circuit may be stopped by mistake.

The present invention has solved these problems, and an object of the present invention is to provide a duplex power supply device that prevents overshoot of the output voltage when starting up one power source of the duplex power supply device.

Means for Solving the Problems> Figure 1 is a block diagram illustrating the present invention that achieves the above object. In Figure 0, two DC sources PS each input DC power and generate Output D C/D
The DC/DC converter unit 10 has an output stabilizing north circuit 20 that supplies a control signal to the DC/DC converter unit 0 in a direction in which the output voltage of the DC/DC converter unit 10 matches a predetermined voltage. . The duplex power supply device is equipped with a matching means for matching the output voltages of each DC power source and supplying it to the load, and a switching means SW for determining when to turn on one DC power source independently of the other DC power source. ing.

As a configuration unique to the present invention, a means 30 for detecting the output voltage of the DC power source and a signal output from the output voltage detecting means of the other power source are inputted, and a load sharing signal to be balanced with the output voltage of the other power source is sent to the own power source. The present invention is characterized by comprising a load share circuit 40 that outputs the load share signal to the output stabilizing circuit, and a soft start circuit 50 that delays the rise time of the DC/DC converter section 10 when sending the load share signal to the output stabilization circuit. There is.

Functions Each component of the present invention has the following functions. The switch means turns on the power supply while one power supply is in operation, such as during online maintenance.

A load sharing circuit balances the currents borne by both power supplies while they are in operation, and when both power supplies start up with a time difference, overshoot occurs on the side that started up later. Therefore, the soft start circuit allows the power supply that started up later to operate independently until it enters a steady state, and then allows the load sharing circuit to intervene and perform cooperative operation.

<Example> The present invention will be explained below using the drawings.

FIG. 2 is a circuit diagram showing one embodiment of the present invention.

In FIG. 2, parts having the same functions as those in FIG. A voltage V in is applied, and a switching element Q such as a transistor is turned on and off. Then, a switching signal is induced in the secondary winding n2 of the transformer, so it is rectified by diodes DI, D2, high frequency components are removed by choke coil L1, and smoothed by capacitor C1, resulting in output voltage E2. It has gained. The output stabilizing circuit 20 here includes an error amplifier circuit 21, a pulse width control circuit 22, a start/stop control circuit 23, and a drive circuit 24 that sends a control signal to the switching element Q.

The output voltage detection means 30 here includes resistors R1 and R2, and a diode D3 to detect the output voltage Vmt of each DC power supply PS.
However, the output voltage E2 may be divided without using the diode D3.

The load sharing circuit 40 has a comparator U2, the positive terminal of which is supplied with the output voltage E1 of the other DC power supply PSI via the resistor R7, and the negative terminal of which is supplied with the own power supply PS
The output voltage E2 is supplied. The negative terminal and the positive terminal are connected by a resistor R6, and a resistor R7.
is equivalent to Then, the output voltage E2 becomes the output voltage E1
When it is lower than , the output of comparator U2 is H. The soft start circuit 50 includes a CR time constant circuit and a start/start function based on the output signal E3 of this time constant circuit.
It consists of a transistor Q1 that changes the state of the stop control circuit 23. The CR time constant circuit is a comparator U2
It consists of a resistor R5 connected to the output terminal of the resistor R5, and a capacitor C2 whose one end is connected to this resistor R5 and the other end is grounded. This is slightly longer than the rise time until the power is stored. The transistor Q1 has an emitter terminal connected to the other end of a resistor R5, a collector terminal grounded, and a base terminal connected to a start/stop control circuit 23 (usually consisting of a gate circuit) via a diode D4.

The control signal E3 of the soft start circuit 50 is connected to the diode D.
5 to the positive terminal of the amplifier U1 of the error amplification circuit 21. Additionally, fl! is connected to the positive terminal of amplifier U1. ! A resistor R4 whose @ is grounded is connected in parallel with a circuit in which the resistor R4 and a constant voltage source Vref are connected in series. An output voltage v x divided by the output voltage detection means 30 is connected to the negative terminal of the amplifier U1.

The error signal output from the error amplifier circuit 21 is sent to the pulse width control circuit 22, and a control signal is output in a direction to reduce this error signal. The drive circuit 24 is, for example, a gate circuit, and sends the control signal of the pulse width control circuit 22 to the switching element Q only when the start/stop control circuit 23 allows the operation.

The operation of the device configured in this manner will be described next. Third
The figure is a waveform diagram illustrating the start of operation of the apparatus shown in FIG. 2, and shows voltages E1, 2, and 3, on/off of the switch SW, and the output signal of the start/stop control circuit 23. First, the DC power supply PSI is turned on, the switch SW is turned on, and a little later the control signal of the start/stop control circuit 23 is set to the start mode, and the DC power supply PSU is turned on.
The C/DC converter section 10 starts operating, and the output voltage E
2 gradually increases. Since the soft start circuit N50 suppresses the operation of the load sharing circuit 40, the error amplification circuit 21 can maintain the output voltage E at the set voltage of the DC power supply PS.
2 enters the steady state. Thereafter, the soft start circuit 50 starts operating, but this is because the voltage E3 of the time constant circuit has increased to the extent that the diode D5 becomes conductive. As a result, the load share circuit 40 operates so that the output voltage E2 increases to a voltage commensurate with the output voltage E1, and no overshoot occurs.

In the above embodiment, a CR time constant circuit is shown as the soft start circuit 50, but the present invention is not limited to this, and other devices such as a timer may be used. Further, the soft start circuit 50 may be provided in both power supply devices, or may be provided in only one.

<Effects of the Invention> As explained above, according to the present invention, since the soft start circuit 50 is provided in the load sharing circuit 40, when starting up the other power supply while one power supply is operating, which occurs during online maintenance, etc. There is no overshoot and the operation is stable.

[Brief explanation of drawings]

FIG. 1 is a configuration block diagram showing one embodiment of the present invention, and FIG.
The figure is a specific circuit diagram, Figure 3 is a waveform diagram explaining the operation of the circuit in Figure 2, Figure 4 is a block diagram of the configuration of the conventional device, and Figure 5 is an explanatory diagram of problems with the conventional device. . DESCRIPTION OF SYMBOLS 10... DC/DC converter part, 20... Output stabilization circuit, 30... Output voltage detection means, 40... Load sharing circuit, 50... Soft start circuit.

Claims (1)

[Claims] A DC/DC converter unit that inputs DC power and outputs a DC current, and a control signal to the DC/DC converter unit in a direction in which the output voltage of the DC/DC converter unit matches a predetermined voltage. It is equipped with two DC power supplies each having an output stabilization circuit, and also includes means for matching the output voltage of each DC power supply and supplying it to the load, and the timing of turning on one DC power supply is independent from that of the other DC power supply. In a redundant power supply device, a means for detecting the output voltage of the DC power supply and a load sharing device that inputs a signal output from the output voltage detection means of the other power supply and balances it with the output voltage of the other power supply. It is characterized by comprising a load share circuit that outputs a signal to its own power source, and a soft start circuit that delays the load share signal in comparison to the rise time of the DC/DC converter section when sending the load share signal to the output stabilization circuit. A soft start circuit for a redundant power supply.