JPH02311127A - Redundant power supply system - Google Patents

Abstract

PURPOSE: To de-energize a defective power supply from a system by producing a zero output from a differential amplifier when conduction of a diode is interrupted and equaling the input voltage of the diode to the output voltage of a shared load when it is deviated from the zero output of the differential amplifier. CONSTITUTION: Since the voltage drop across a series diode goes zero V upon interruption of power supply from a specific power supply, each power supply in stand-by mode is left in active mode. When 0V of a first amplifier is discriminated from the diode input voltage, the diode input voltage is regulated to a level equal to the output voltage VOUT across a common load. This operation prevents interruption of the power supply operating in stand-by mode and a power supply state is indicated accurately through a voltage sensitive self-test.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention is a redundant system designed so that one of the power supplies can supply the entire system power required and the remaining power supplies are used for backup. Regarding power supply system.

BACKGROUND OF THE INVENTION The output terminals of a redundant power supply are typically connected together to a system load through a diode that isolates the failed power supply from the system by reverse biasing a diode in series with the failed power supply. The output voltage feedback signal of these power supplies is typically derived from the load side of a diode, which requires precise voltage regulation.

The problem encountered in such feeder configurations is that there is always a small variation in output voltage between the redundantly connected individual feeders, so that the load power is fed from the feeder with the maximum (highest) output voltage. It is to be done. The power supplies with initially low output voltages are in standby mode and their output voltages are continuously reduced to near Ov, which makes it appear that the output voltage of the load is always too high for the control loops of these individual power supplies, This is to continuously reduce the output voltage from there. Therefore, the error voltage continuously drives the low output voltage power supply into the off state since the output voltage of the load remains constant. Therefore, conduction is blocked by the reverse biased series diode at the output of each standby power supply, effectively opening the feedback control loop. Because a power source operating in standby mode is thus effectively disconnected, self-tests of the power source often indicate a fault condition even if the power source is practically capable of being restored to full operation. .

Another problem arises from the sudden failure of a redundant active power supply, resulting in a transient voltage dropout when one of the power supplies operating in standby mode recovers and assumes active mode. The output filtering capacitor of the standby power supply is nearly discharged and requires some time to charge to the appropriate output voltage. If the active power supply fails rapidly enough, this time will cause a voltage dropout condition at the load.

In accordance with the present invention, the aforementioned problems encountered in prior art redundant power supply systems are minimized and a redundant power supply system is provided in which all power supplies of the system are always powered up and defective power supplies are de-energized from the system. be done.

The foregoing is accomplished by altering the generation of the voltage feedback signal when compared to the prior art and avoiding opening the control loop when the diode stops conducting.

In summary, the foregoing is accomplished by providing a first differential amplifier that produces an output voltage equal to or proportional to the voltage drop across a series diode from each power supply to the load. A second differential amplifier then generates the difference of this voltage or an appropriately scaled voltage from the series diode input voltage.

The output voltage of the second amplifier is made equal to or proportional to the output power across the shared load. With this circuit, the control loop remains active in power supplies that do not supply load current in a redundant configuration, ie standby power supplies.

In operation, when the series diode stops conducting, the voltage drop across the series diode drops to QV, resulting in a zero output from the first differential amplifier. Thus, when the second amplifier produces a difference of Ov from the diode input voltage of the output of the first amplifier, the diode input voltage is regulated to a value equal to the output voltage across the shared load. This action avoids shutting down the power supply operating in standby mode and allows the voltage sensing self-test to indicate a bus condition. Additionally, because the output filtering capacitor is charged to approximately the correct voltage rather than the nearly discharged state that exists in prior art circuit configurations, this technique also reduces the potential for power dropouts in the event of a sudden failure of the active power supply. is reduced.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1, a block diagram of a prior art redundant power supply system is shown in which only one of the power supply devices is designed to provide the required full load power.

The remaining power supply is only used as a backup in case the power supply supplying power fails for some reason. This system includes a plurality of power supply devices 1, 2 .
.・・・・・・
- An output voltage, Vout, can be supplied via Dn. A feedback signal is sent from the output load to each power supply for voltage regulation.

As is well known, each power supply in the system is regulated by the same output voltage, but the separate power supplies do not provide the same output voltage to the load RL through their respective diodes. Therefore, only the diode associated with the system power supply providing the highest voltage is forward biased, so that all load power is drawn from that power supply. The remaining power supplies are in standby mode and their feedback voltage provides an indication that the output is too high, reducing their output voltage to near zero, resulting in a reduction in output voltage. Since Vout remains constant, the error voltage fed back to each power supply in standby continues to increase,
Drives a power supply device in standby mode to an off state. Therefore, the control loop is effectively opened by blocking conduction by the reverse biased series diode. Due to this effective disconnection of the power supply when operating in standby mode, self-tests of the power supply often indicate a fault condition even when the power supply can be practically restored to a fully operational state. It is this problem that is alleviated by the present invention.

Referring to FIG. 2, a circuit diagram of a control signal technique is shown in which all active power supplies of a redundant system are continuously powered up and provide power immediately upon request. The circuit has the same power supply devices 1, 2 . ......N and the same diodes DI, D2. ...Contains DN.

Prior art redundant power supply systems connect the feedback line of each power supply to a first operational amplifier U11. U21.・・・・・・U
Nl, whose input is connected to each output diode DI, D2 . ...It is improved by applying from both sides of the DN. The first amplifier includes a feedback resistor R1. Therefore, the output of each first amplifier is connected across the associated output diode or Vout
and the output of each power supply, or is proportional to it. This differential voltage is then applied to the second differential amplifier U21.
U22. . . . At UN2, the difference between the output voltages of the respective power supply devices is taken, and the input signal thereto is given via the same resistor R2. The second amplifier has a feedback resistor R
Contains 2. The output of the second differential amplifier provides a regulated feedback voltage to each power supply.

Amplifier U11. U21. ...UNI and amplifier U12. U22゜... It is preferable that all UN2s are amplifiers with a gain of 1, but each power supply device can operate properly even if the relationship between the related amplifiers is changed, so it is possible to This condition is not important for normal operation.

It can be seen that each power supply that is in standby mode in the circuit of FIG. 2 remains in active mode because when conduction from a particular power supply ceases, the voltage effect across the series diode drops to Ov. Therefore, once Ov at the output of the first amplifier is differentiated from the diode input voltage (power supply output voltage), the diode input voltage is then adjusted to a value equal to the output voltage across the shared load (Vout). .

This operation avoids disconnection of the power supply operating in standby mode, and the voltage sensing self-test can accurately indicate the power supply status.

Although the invention has been described with respect to specific embodiments thereof, various changes and modifications will be apparent to those skilled in the art. It is therefore intended that the claims be interpreted as broadly as possible in light of the prior art, including all such changes and modifications.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional redundant power supply system, and FIG. 2 is a circuit diagram of a redundant power supply system with improved control signals according to the present invention. Explanation of reference symbols 1.2. ......n...Power supply device DI, D2.・
...Dn...Diode RL...Load Ull, U21. ...UNI, U12. U22
．．・・・・・・UN2・・・Differential amplifier

Claims (9)

[Claims] (1) In a redundant power supply system, the system (a
) a plurality of power supply devices each having a power supply output terminal and a power supply return terminal; (b) a system output terminal for connecting the output of the power supply system to a load; a plurality of diodes connected between the terminal and the system output terminal; (d) a feedback circuit for each power supply device, each feedback circuit comprising: (e) a plurality of diodes connected across the diode associated with the power supply device; (f) second means for providing a signal to the feedback terminal indicating a difference between the voltage of the power supply output and the signal indicating the voltage drop across the diode; A redundant power supply system equipped with (2) The system according to claim (1), wherein the first
The means for a redundant power supply system is a first differential amplifier having a pair of inputs connected across said diode. (3) In the system according to claim (1), the second
a redundant power supply system, wherein the means is a second differential amplifier having an input connected to a power supply output terminal of an associated power supply device and a second input connected to said first means. (4) In the system according to claim (2), the second
a redundant power supply system, wherein the means is a second differential amplifier having an input connected to a power supply output terminal of an associated power supply device and a second input connected to an output of said first means. (5) The system according to claim (2), wherein the first
said inputs of said means include a first resistor having a predetermined resistance value connected to the cathode of said diode and one of said inputs of said first amplifier; second and third series resistors connected between the anode of the diode and a reference voltage, the junction of the second and third resistors being connected to another input of the first amplifier; Redundant power supply system. (6) The system according to claim (4), wherein the first
said input of said means comprises a first resistor having a predetermined resistance value connected between said diode cathode and said one of said inputs of said first amplifier; and second and third series resistors connected between the anode of the diode and a reference voltage;
and a third resistor junction connected to another input of said first amplifier. (7) In the device according to claim (3), the input of the second means is connected to a second predetermined resistor connected between the output of the first means and the input of the second amplifier. and fifth and sixth series resistors each having said second predetermined resistance value and connected between the anode of said diode and a reference voltage; The junction of the fifth and sixth resistors is connected to another input of the second amplifier. (8) In the device according to claim (4), the input of the second means is connected to a second predetermined resistor connected between the output of the first means and the input of the second amplifier. a fifth and sixth series resistor each having said second predetermined resistance value and connected between the anode of said diode and a reference voltage; A redundant power supply system, wherein the junction of the fifth and sixth resistors is connected to another input of the second amplifier. (9) The system according to claim (6), wherein the second
said input of said means includes a fourth resistor having a second predetermined resistance value connected between said first means output and said input of said second amplifier; fifth and sixth series resistors having a predetermined resistance value and connected between the anode of the diode and a reference voltage; a junction of the fifth and sixth resistors is connected to the second amplifier; Redundant power supply system connected to another input of the.