JP2001103754A - Power supply unit for redundant power system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply unit for a redundant power system with proper measures taken so as not to feedback as to significantly reduce the output voltage of a switching power circuit in a standby. SOLUTION: The cathode of an output diode 1 is connected to an output terminal 2 connected to a load supply path, and the output of variable output voltage switching power circuit 3 is led out to the output terminal 2 through the output diode 1. This power circuit is provided with a resistor potential dividers R1, R2, R31, R32 detecting the load voltage V1 generated at the output terminal 2, an error amplifying circuit 4 for amplifying an error between detected voltage Vf from the circuits R1, R2, R31, R32 and reference voltage Vs, a pulse width control circuit 5 variably controlling the pulse width of the switching signal on the switching power circuit 3 according to the output of the error amplifier circuit 4. A voltage comparing circuit 9 is mounted which compares the anode and cathode potentials of the output diode 1, and is formed so that the output of the circuit 9 may act on the resistor potential divider when the cathode potential is increased, and the detected voltage Vs inputted into the error amplifying circuit 4 may be reduced as appropriate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply unit for a redundant power supply system adapted for redundant operation by connecting a plurality of power supply units to a common load, and more particularly to an output voltage in a standby operation state. It relates to technical improvements that suppress fluctuations.

[0002]

2. Description of the Related Art For example, a power supply system of a high-reliability computer system has a configuration in which a plurality of power supply devices are connected to a common load (such as a computer) to perform redundant operation so that power supply is never interrupted. I have. This is called a redundant power supply system.

FIG. 1 shows an example of a conventional typical configuration of a power supply device for a redundant power supply system. In this device, the cathode of the output diode 1 at the last stage is connected to the output terminal 2 connected to the load power supply line, and the output of the switching power supply circuit 3 of variable output voltage is led to the output terminal 2 via the output diode 1. Is done. In addition, a resistor voltage dividing circuit R1 for detecting the load voltage Vl generated at the output terminal 2
R2, R3, an error amplifier circuit 4 for amplifying an error between the detected voltage Vf and the reference voltage Vs by the resistor voltage divider circuits R1, R2, R3, and a switching power supply circuit 3 according to the output of the error amplifier circuit 4. A pulse width control circuit 5 for variably controlling the pulse width of the switching signal.
Thus, a feedback control system is configured to maintain the output voltage Vout of the switching power supply circuit 3 at a constant value based on the detection voltage Vf.

As illustrated in FIG. 1, a load 6 is connected to the output terminal 2, and another power supply 7 having the same configuration as that of the present device is connected to a power supply path to the load 6. Although not shown, another power supply device 7 is also connected to the load 6 via the output diode of the last stage. Although the two power supplies are designed to output the same voltage, it is practically difficult to output completely the same voltage, and there is a slight difference between the output voltages of the two power supplies. Since both devices are connected to the load 6 via the output diode 1, power is supplied to the load 6 from the higher voltage device,
No power is supplied to the load 6 from the lower voltage side device. The power supply device that supplies the load power is referred to as a working device or a working state, and the power supply device that does not supply the load power is referred to as a standby operation device or a standby operation state.

[0005]

The above-mentioned conventional device is,
There is a problem that the output voltage of the switching power supply circuit 3 drops significantly below a specified value in the standby operation state. This output reduction occurs by the following mechanism.

[0006] Since his own output voltage is lower than the output voltage of the other power supply device 7, he has taken the role of the standby operation device. Therefore, the anode potential of the output diode 1 in the standby operation device (the output voltage of the own switching power supply circuit 3) is lower than the cathode potential (the voltage output by the active device = load voltage Vl). However, in the standby operation device, the load voltage Vl is applied to the voltage dividing resistance circuits R1, R2, and R3, and the feedback control system uses the switching power supply circuit 3 based on the detection voltage Vf obtained by dividing the load voltage Vl. The output voltage Vout is controlled (this is a configuration for supplying a constant voltage to the load 6 in a working state).

For the standby operation device, since the load voltage Vl is higher than the specified value, the control works to lower the feedback voltage, and the pulse width control circuit controls the output voltage Vout of the switching power supply circuit 3 to lower. 5 As a result, the output voltage Vout of the standby operation device drops significantly from the specified value.

When the output of the working device 7 is interrupted due to some abnormality, the standby operation device is immediately switched to the working device, and the power supply to the load 6 must be continued. However, if the output voltage Vout of the switching power supply circuit 3 is lower than the specified value in the standby operation state, it takes time before the output of the specified voltage can be supplied to the load 6 as an active device. The load voltage Vl is greatly reduced. In the case of a configuration in which the output of another system of the switching power supply circuit 3 is supplied to another load in the standby operation state, the fact that the output of the switching power supply circuit 3 is greatly reduced by the above-mentioned mechanism means that the output of the other system is also reduced. It has a direct effect.

In order to alleviate the problem described in detail above, the diode 8 and the resistor R4 are added in the conventional device of FIG. The resistor R4 is connected between the output of the switching power supply circuit 3 and the ground, and has a very large value that consumes almost no current.
The cathode of the diode 8 is connected to the anode of the output diode 1, and the anode of the diode 8 is connected to the resistors R1 and R2.
Connected to the connection point.

When this device is in a standby operation state and the load voltage Vl becomes considerably higher than the anode potential of the output diode 1, the diode 8 is turned on and the load voltage Vl generated by the output of the other power supply circuit 7 is changed to the resistance R1. And the diode 8 to the output side of the switching power supply circuit 3 to prevent the voltage at this point from lowering.

The above countermeasures merely prevent an apparent voltage drop by introducing an external voltage to the output terminal of the switching power supply circuit 3, and the feedback voltage control system reduces the output voltage Vout of the switching power supply circuit 3. There is no change in the fact that it is acting so as to greatly reduce it. Therefore, the above-mentioned problem is not substantially improved.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems of the prior art, and an object thereof is to prevent a control action that greatly reduces the output voltage of a switching power supply circuit from operating in a standby operation state. It is an object of the present invention to provide a power supply device for a redundant power supply system in which measures are taken.

[0013]

According to the present invention, in a power supply device for a redundant power supply system having a basic configuration described in the section of the prior art, an anode potential and a cathode potential of the output diode are directly or indirectly connected. A voltage comparison circuit for comparison is provided, and when the cathode potential becomes higher, the output of the voltage comparison circuit acts on the resistance voltage dividing circuit to appropriately reduce the detection voltage input to the error amplifier circuit. The circuit was configured as follows.

[0014]

FIG. 2 shows a schematic configuration of a power supply device for a redundant power supply system according to an embodiment of the present invention. The basic configuration is the same as that of the conventional device shown in FIG. 1. The cathode of an output diode 1 at the last stage is connected to an output terminal 2 connected to a load power supply line. It is led to the output terminal 2 via the output diode 1. Further, resistance voltage dividing circuits R1 and R1 for detecting the load voltage V1 generated at the output terminal 2.
2, R31, R32 and the resistance voltage dividing circuit R1, R2, R31
An error amplifier circuit 4 for amplifying an error between the detection voltage Vf and the reference voltage Vs due to R32, and a pulse width control circuit for variably controlling the pulse width of the switching signal in the switching power supply circuit 3 according to the output of the error amplifier circuit 4 5 is provided. Thus, a feedback control system is configured to maintain the output voltage Vout of the switching power supply circuit 3 at a constant value based on the detection voltage Vf. In a use state, the load 6 is connected to the output terminal 2, and another power supply device 7 having the same configuration as that of the present device is connected to a power supply path to the load 6. Although not shown, another power supply device 7 is also connected to the load 6 via the output diode of the last stage.

In the device of the present invention, a voltage comparison circuit 9 is provided for comparing the anode potential and the cathode potential of the output diode 1 with each other. Switching power supply circuit 3
And the resistors R5 and R6 are connected in series between the output terminal of R1 and the connection point of the resistors R31 and R32 (one end of R6 may be grounded),
The voltage at the connection point between the resistors R5 and R6 is applied to the plus input of the voltage comparison circuit 9. This input voltage is a voltage corresponding to the anode potential Vout of the output diode 1. Further, the voltage at the connection point between the resistors R1 and R2 on the cathode side of the output diode 1 is applied to the minus input of the voltage comparison circuit 9. This voltage corresponds to the cathode potential Vl of the input voltage output diode 1 on the minus side.

The output of the voltage comparison circuit 9 is connected via a forward diode 10 to the connection point between the resistors R1 and R2. When this device is in a working state, the load voltage Vl generated at the output terminal 2 is equal to the output voltage Vou of the switching power supply circuit 3.
t, the output diode 1 is on, and the anode potential is higher than the cathode potential. In this working state, the voltage on the positive input side of the voltage comparison circuit 9 is higher than the voltage on the negative input side, the diode 10 is off, and the voltage comparison circuit 9 is connected to the voltage dividing resistance circuits R1, R2, R31, and R32. It has no particular effect. The feedback control system maintains the load voltage Vl at a specified value by controlling the output voltage Vout of the switching power supply circuit 3 based on the detection voltage Vf detected by the voltage dividing resistor circuits R1, R2, R31, and R32.

When the device is in a standby operation state, the load voltage Vl generated at the output terminal 2 is higher than the output voltage Vout of the switching power supply circuit 3, and the output diode 1 is off. If the difference between the load voltage Vl and the output voltage Vout at this time is large to some extent, the voltage on the minus input side of the voltage comparison circuit 9 becomes higher than the voltage on the plus input side, and the diode 10 turns on. Then, a current flows from the output terminal 2 to the ground through the resistor R1, the diode 10, and the open collector output transistor of the voltage comparison circuit 9. This current is called a current increase. With this increased current,
The voltage drop due to the resistor R1 is larger than in the actual operation state, and the detection voltage V input to the error amplifier circuit 4 is correspondingly increased.
s decreases. That is, the load voltage Vl appears to be low for the error amplifier circuit 4.

By the above mechanism, the feedback voltage control system functions properly, and the output voltage Vout of the switching power supply circuit 3 in the standby operation device does not drop too much.

[0019]

According to the present invention, the feedback voltage control system does not act so as to greatly reduce the output voltage of the internal switching power supply circuit as in the prior art even in the standby operation state. Therefore, when it is necessary to switch from the standby operation state to the actual operation state, the specified voltage can be instantaneously supplied to the load. In the standby operation state, a prescribed voltage can be supplied even if the output of another system of the switching power supply circuit 3 is supplied to another load.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a power supply device for a conventional representative redundant power supply system.

FIG. 2 is a schematic configuration diagram of a power supply device for a redundant power supply system according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 output diode 2 output terminal 3 switching power supply circuit 4 error amplifier circuit 5 pulse width control circuit 6 load 7 other power supply device 8 diode 9 voltage comparison circuit 10 diode R1, R2, R31, R32 voltage dividing resistance circuit

Continued on the front page (72) Inventor Tsutomu Ozawa 5-36-11 Shimbashi, Minato-ku, Tokyo F-term in Fuji Electric Chemical Co., Ltd. 5G065 BA00 BA02 DA02 GA06 HA04 JA01 LA01 MA09 MA10 NA02 NA06 5H730 AA00 AS01 AS19 BB84 FD01 FF05 FG25

Claims (1)

[Claims] An invention of a product specified by the following items (1) to (4). (1) A power supply device for a redundant power supply system adapted for use in performing redundant operation by connecting a plurality of power supply devices to a common load. (2) The cathode of the last output diode is connected to the output terminal connected to the load power supply path, and the output of the variable output voltage switching power supply circuit is led to the output terminal via the output diode. (3) A resistor voltage dividing circuit for detecting a load voltage generated at the output terminal, and an output voltage of the switching power supply circuit is set to a constant value based on an error between a voltage detected by the resistor voltage dividing circuit and a reference voltage. And an error amplifier circuit for performing feedback control so as to maintain (4) There is a voltage comparison circuit for directly or indirectly comparing the anode potential and the cathode potential of the output diode, and when the cathode potential becomes higher, the output of the voltage comparison circuit becomes the resistance voltage dividing circuit. And the circuit is configured to appropriately reduce the detection voltage input to the error amplifier circuit.