JP3472407B2 - Parallel current balance type redundant operation circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel current balance type redundant operation circuit in which output sides of a plurality of power supply devices are connected in parallel to a load to achieve parallel current balance.

[0002]

2. Description of the Related Art As a conventional normal redundant operation circuit, for example, there is one shown in FIG. In FIG. 5, for example, when 100 W output is required for the load 11,
Two 100 W power supply devices 12 and 13 are prepared, one power supply device 12 and the load 11 are connected through the diode D11, and the other power supply device 13 and the load 11 are connected to the diode D12.
Connect through. These two power supplies 12, 13
Among them, even if one power supply device 12 is broken, the output can be taken out from the other power supply device 13.

However, in this redundant operation circuit, since the output voltages of the two power supply devices 12 and 13 vary, the load current flows to the load 11 from only one of the power supply devices 12 and 13. Since there is no power supply 12,
13 has a shorter life. Therefore, as shown in FIG. 6, a redundant operation circuit that balances currents by using power supply devices 1A and 1B having a parallel operation current balance mechanism has been considered. In the power supply device 1A and the power supply device 1B, the current balance terminals 14 and 15 are mutually connected. A specific circuit of this redundant operation circuit is shown in FIG.

In FIG. 7, two power supply devices 1A and 1B are provided.
Is connected in parallel to the load 2 and the power supplies 1A and 1B are connected.
Each of them has an output control circuit 3 and an amplifier 4, and has a resistor R1.
The output voltage V0 is divided by R2 and R2 and input to the amplifier 4, and a predetermined voltage is given from the amplifier 4 to the output control circuit 2 by the difference voltage of the reference voltage Vr generated by the Zener diode ZD so that the output voltage V0 becomes a constant voltage. It is controlled to become.

On the other hand, in order to balance the current, a current transformer 5 forming a part of the current detection circuit is provided,
The detection voltage of the current transformer 5 is rectified by the diode D0 to charge the capacitor C0 as the DC detection voltages Vi1 and Vi2, and the capacitor C0 has a resistor R3 for current-voltage conversion.
Are connected in parallel, current transformer 5, diode D
0, the capacitor C0, and the resistor R3 form a current detection circuit. The current detection circuits are connected to each other via a voltage detection resistor R0.

For example, when the output current I1 of the power supply device 1A is larger than the output current of the power supply device 1B (I1> I2)
Since the detection voltages of the current transformer 5 are Vi1> Vi2, the unbalanced current i flows from the power supply devices 1A to 1B, and the direction and magnitude of the unbalanced current is changed by the voltage detection resistor R0. A voltage Vi having a corresponding polarity is generated.

The voltage Vi generated in the resistor R0 is
Since the voltage is divided by the resistor R2 and added to the voltage and input to the negative input terminal of the amplifier 4, the output of the amplifier 4 decreases. As a result, in the power supply device 1A, the output control circuit 2 operates so as to reduce the output current I1, while in the power supply device 1B, the output control circuit 2 operates so as to increase the output current I2.
Is operated and the unbalanced current i = 0 is set to automatically maintain the balanced state of I1 = I2.

However, in this parallel current balance type redundant operation circuit, when one power supply unit 1B of the power supply units 1A and 1B fails, the detection voltage Vi2 is lowered and the unbalanced current i is supplied to one power supply unit. The voltage V + i flowing through the resistor R3 of the device 1B and generated in the resistor R0 increases, and the amplifier 4
The input voltage input to the negative input terminal of the amplifier increases, the output voltage of the amplifier 4 decreases, and the output V0 of the output control circuit 3 decreases. That is, when either one of the power supplies 1A and 1B is stopped, the normal power supplies 1A and 1B
In order to maintain the power source balance by lowering the output voltage V0, the output voltage V0 lowers.

A parallel current balance type redundant operation circuit for preventing such a decrease in output voltage is shown in FIG. This redundant operation circuit includes power supply devices 1A, 1
When the analog switches 16 and 17 are provided between the power supply balance terminals 14 and 15 of B, and the abnormality of the power supply devices 1A and 1B is detected, the analog switches 16 and 17 are turned off to disconnect the power supply devices 1A and 1B. It was done like this. A specific circuit of this redundant operation circuit is shown in FIG.

In FIG. 9, the power supply devices 1A and 1B are provided with photomos relays 16A and 1A as an analog switch, each of which includes a light emitting diode D13 and a light receiving transistor Tr11.
7A are provided respectively, and a normal or abnormal operation signal is output from the output control circuit 3 to the light emitting diode D13. When the normal operation signal is given to the light emitting diode D13, the photo MOS relays 16A and 17A are turned on, and the unbalanced current i flows through the resistor R3. Power supply 1
A and 1B are damaged and abnormal operation signal is emitted by light emitting diode D1.
3 is output to the photo MOS relays 16A, 17
A is turned off, the unbalanced current i does not flow in the resistor R3, and the power supply devices 1A and 1B are disconnected. Since no voltage is generated in the resistor R0, the output voltage V0 does not decrease.

An example of the configuration of the output control circuit 3 that outputs a normal or abnormal operation signal is shown in FIG. In FIG. 10, reference numeral 16 denotes an output transformer that operates by turning on and off the transistor Tr12. A rectifying circuit including diodes D14 and D15 and a smoothing circuit including a coil C11 and a capacitor C11 are provided on the secondary winding 17 side of the output transformer 16. Is provided. The auxiliary winding 18 has a diode D16 for rectification, a capacitor C12 for charging the rectified voltage,
The discharge resistors R11 are connected to the auxiliary winding 18
Outputs a normal or abnormal operation signal. For this reason,
There is a failure that cannot be detected by this normal or abnormal operation signal. For example, if there is an open failure near the output,
In the previous stage, the abnormal operation signal for judging failure is not output during full operation.

[0012]

However, in such a conventional parallel current balance type redundant operation circuit as described above, in the case of FIGS. 6 and 7, if one power supply device fails, the other power supply device There was a problem that the output voltage would decrease. In addition, as shown in FIGS. 8 and 9, when a failure of the power supply device is detected and separated by an analog switch, the circuit becomes complicated, and if detection of the failure is slow, the output voltage instantaneously drops, Further, there is a problem that there is a failure that cannot be detected depending on the detection method.

The present invention has been made in view of the above-mentioned conventional problems. Even if a failure occurs in one of the power supply devices, the output voltage does not drop, and the circuit is simple in parallel. An object is to provide a current balance type redundant operation circuit.

[0014]

In order to achieve this object, the present invention is constructed as follows. First, the present invention is
The present invention is intended for a parallel current balance type redundant operation circuit in which the output sides of a plurality of power supply devices that generate stable outputs are connected in parallel to a load. Regarding such a parallel current balance type redundant operation circuit, according to the present invention, a stabilized output according to a difference voltage between an input voltage obtained by dividing the output voltage and a predetermined reference voltage is obtained in each of the plurality of power supply devices. In this way, the amplifier that controls the output control circuit, the current detection circuit that detects the output current supplied to the load and the output side is connected to each other, and the predetermined polarity according to the current from the detection voltage detected by the current detection circuit And a voltage generating means for biasing the input voltage of the amplifier by generating a voltage of a predetermined polarity according to the unbalanced current flowing when a difference occurs in the voltage or the detected voltage, and one of the power supply devices has failed. At this time or when there is a difference in the detection voltage, a diode that prevents the unbalanced current from flowing, and when the detection voltage is balanced, both currents from each detection voltage flow, causing a difference in the detection voltage. When I INTRODUCTION both current was reduced by the amount of unbalanced current and unbalanced current flows, when the fault is characterized in that a constant current circuit through which only a current from one of the detection voltage.

In the present invention, a resistor having a predetermined resistance value may be provided instead of the constant current circuit. In the present invention, the value of the voltage generating means and the value of the constant current circuit are set so that the drop in the output voltage is a value that does not cause a problem in specifications. Also,
In the present invention, a circuit including a diode and a constant current circuit may be connected to the outside of the power supply device.

In the present invention, the constant current circuit is 1
Individual pieces may be connected between the diodes. According to the parallel current balance type redundant operation circuit of the present invention having such a configuration, the diode prevents the unbalanced current from flowing when one of the power supply devices fails or a difference in the detected voltage occurs. , When the detection voltage is balanced, both currents from each detection voltage flow, and when there is a difference in the detection voltage, both the unbalanced current and the current reduced by the unbalanced current are generated. When the current flows and fails, only the current from one of the detected voltages is made to flow, so that the decrease in the output voltage can be set to a value at which there is no problem in specifications. Also,
Since no analog switch is used, the circuit is simple and the output voltage does not drop instantaneously. Further, the current can be balanced without detecting a failure.

A resistor having a predetermined resistance value may be provided instead of the constant current circuit, but in this case, the performance is slightly inferior. Further, since the value of the voltage generating means and the value of the constant current circuit are appropriately selected, the output voltage can be reduced to a value that causes no problem in specifications. Moreover, since a circuit including a diode and a constant current circuit may be connected to the outside of the power supply device, the conventional circuit can be used as it is.

Furthermore, when one constant current circuit is connected between the diodes, the circuit structure can be further simplified.

[0019]

1 is a diagram showing a parallel current balance type redundant operation circuit of the present invention. In FIG. 1, 1A,
1B is a power supply device, and the power supply devices 1A and 1B have a load 2
Are connected in parallel via diodes D3 and D4.
Balanced currents I1 and I2 are supplied to the load 2 from the power supply devices 1A and 1B. The diodes D3 and D4 are provided for redundant operation even if the power supply devices 1A and 1B are short-circuited, and may be omitted if it is considered that the failure is small.

Reference numeral 3 denotes an output control circuit provided in the power supply devices 1A and 1B. The output voltage V0 stabilized by the output control circuit 3 is supplied to the load 2 connected in parallel, and the output to the load 2 is output. The voltage V0 is divided by the resistors R1 and R2 and is applied to the (−) input terminal of the amplifier 4, where (+)
Fixedly set a predetermined reference voltage to the input terminal,
For example, a Zener diode ZD is connected. The amplifier 4 amplifies the output voltage V0 based on the difference voltage between the voltage obtained by dividing the output voltage V0 by the resistors R1 and R2 plus the voltage + Vi generated by the resistor R0 as the voltage generating means and the reference voltage of the Zener diode ZD. A certain predetermined voltage is output to the output control circuit 3, and the output voltage V0 of the output control circuit 3 is controlled to be constant.

On the other hand, each of the power supply devices 1A and 1B is provided with a current transformer 5 as one component of a current detection circuit for detecting the output currents I1 and I2 supplied to the load 2. Is rectified by the diode D0 and the capacitor C0 is charged as the detection voltages Vi1 and Vi2. A resistor R3 for current-voltage conversion is connected in parallel to the capacitor C0.

The current detecting circuit composed of the current transformer 5, the diode D0, the capacitor C0 and the resistor R3 provided in each of the power supply devices 1A and 1B is connected to each other via the resistor R0 as the voltage generating means. When the detection voltage Vi1 and the detection voltage Vi2 are equal, the power supply device 1A
Of the detection current from the positive side of the capacitor C0 of the resistor R0,
It flows to the minus side of the capacitor C0 through the constant current circuits Ic1 and Ic2 and the diode D1. Further, the detected current flows from the positive side of the capacitor C0 of the power supply device 1B to the negative side of the capacitor C0 through the resistor R0, the constant current circuits Ic1 and Ic2, and the diode D2. Since the detection currents flowing at this time are equal, an equal voltage + Vi is generated in the resistor R0,
The divided voltage of the resistors R1 and R2 is added and input to the (−) input terminal of the amplifier 4, and the amplifier 4 outputs an equal predetermined voltage based on the difference voltage from the reference voltage, and the output control circuit 3 The output currents I1 and I2 output from are balanced.

For example, when the detection voltage Vi1 ≠ the detection current Vi2 and the unbalanced current i flows, the unbalanced current i flows through the resistor R0, the constant current circuits Ic1 and Ic2, and the diodes D1 and D2. For example, the unbalanced current i as shown by the arrow
Is flowing, the unbalanced current i flows through the resistor R0 into the constant current circuit Ic1 and the constant current circuit Ic2.
On the other hand, a current reduced from the detection voltage Vi2 by the amount of the unbalanced current i flows into the constant current circuits Ic1 and Ic2. Constant current circuit I
Since the unbalanced current i flowing through c1 and Ic2 increases, the resistance R
The voltage + Vi generated at 0 increases in accordance with the increasing current amount, the output of the amplifier 4 decreases, and the output current I1 decreases. On the other hand, since the current flowing through the resistor R0 of the power supply device 1B decreases by the increased current amount, the voltage Vi generated in the resistor R0 decreases according to the decreased current amount and is input to the (−) input terminal of the amplifier 4. The voltage also decreases. For this reason,
The output voltage of the amplifier 4 increases and the output current I2 from the output voltage control circuit 3 increases. Thus, the output current I1,
I2 is balanced.

Here, for example, when one power supply device 1B fails, the unbalanced current i from the detection voltage Vi2 is prevented from flowing to the resistors R0 and R3 of the power supply device 1B. The unbalanced current i flows through the resistor R0, the constant current circuits Ic1 and Ic2, and the diode D1. Therefore, if the values of the resistor R0 and the constant current circuit Ic2 are properly selected, the resistor R0
The voltage Vi generated at 1 can be set to a predetermined value, and the decrease in the output voltage V0 can be prevented from causing a problem in specifications. As described above, when one of the power supply devices 1A and 1B fails, the output voltage V0 decreases due to the unbalanced current i flowing from the one power supply device 1A to the other power supply device 1B. Diode D connected in parallel to
1, D2 is blocked, and a control current for balancing the currents in parallel operation is supplied to the constant current circuits Ic1 and Ic2 connected in series to the diodes D1 and D2.

For example, if the constant current flowing through the constant current circuit Ic1 is 1 milliampere and the constant current flowing through the constant current circuit Ic2 is 1 milliampere, a total current of 2 milliamperes always flows through the constant current circuits Ic1 and Ic2. When the unbalanced current i flowing through the constant current circuits Ic1 and Ic2 increases to 1.2 milliamperes when Vi1> Vi2, the current flowing through the constant current circuits Ic1 and Ic2 by Vi2 becomes 0.8 milliamperes. Decrease. When one power supply unit 1A fails and Vi2 becomes 0V, the unbalanced current i of 2 milliamperes flows in the constant current circuits Ic1 and Ic2, and the current from Vi2 does not flow. Therefore, the resistor R0 and the constant current circuit Ic2
By properly selecting the value of (and Ic1), the voltage + Vi generated in the resistor R0 can be controlled.

As the constant current circuits Ic1 and Ic2, for example, those shown in FIG. 2 are used. The constant current circuit shown in FIG. 2A uses a junction field effect transistor 6, and a resistor R3 is connected between the source and the gate.
The constant current circuit shown in FIG. 2B includes a constant current diode 7. The constant current circuit shown in FIG. 2C is composed of a transistor 8, resistors R4 and R5, and diodes D5 and D6. Further, resistors may be used instead of the constant current circuits Ic1 and Ic2. However, in this case the generated voltage +
The performance of controlling Vi is slightly inferior.

Next, the operation of FIG. 1 will be described. Now, it is assumed that the detection voltage Vi1 and the detection voltage Vi2 are equal. The current from the detection voltage Vi1 flows from the positive side of the capacitor C0 to the negative side of the capacitor C0 through the resistor R0, the constant current circuits Ic1 and Ic2, and the diode D1. The current from the detection voltage Vi2 passes from the positive side of the capacitor C0 through the resistor R0, the constant current circuits Ic1 and Ic2, and the diode D2 to the capacitor C0.
Flows to the negative side of. Voltage generated on the resistor R0 + Vi
Are equal, the input voltages input to the (−) input terminal of the amplifier 4 are also equal, and the output voltages of the amplifier 4 are also equal. Therefore, the output voltage V0 from the output control circuit 3 is equal, and the output currents I1 and I2 are balanced.

It is assumed that in the stable control state of the constant voltage output in which the output voltage V0 is controlled to a constant value, the output current I1 of the power supply device 1A becomes larger than the output current I2 of the power supply device 1B, and the current balance is disrupted. In response to the loss of the current balance of I1> I2, the current transformer 5 of the power supply device 1A is rectified by the diode D0 and the capacitor C
0 is charged with the detection voltage Vi1 according to the output current I1, and the current transformer 5 of the power supply device 1B charges the capacitor C0 with the detection voltage Vi2 according to the output current I2 by rectifying the detection voltage by the diode D0. The detection voltage of V1 is Vi1> Vi2.

Therefore, the power supply unit 1 is provided between the current detection circuits.
As indicated by the arrow from A to 1B, the unbalanced current i flows according to the difference in the detected voltage. The unbalanced current i is the resistance R0,
It flows through the constant current circuits Ic1 and Ic2 and the diode D1.
The unbalanced current i flowing through the current circuits Ic1 and Ic2 increases according to the difference between the detection voltages Vi1 and Vi2. On the other hand, in the power supply device 1B, a current reduced by the unbalanced current i flows through the resistor R0 to the constant current circuits Ic2, Ic1 and the diode D2. The voltage + Vi generated in the resistor R0 of the power supply device 1A rises as the unbalanced current i increases.

This voltage + Vi is + when viewed from the amplifier 4.
The bias voltage is Vi, and the divided voltage for the (−) input terminal of the amplifier 4 is the bias voltage + V generated in the resistor R0.
It increases by i minutes, and as a result, the output of the amplifier 4 decreases,
The output control circuit 3 reduces the output current I0. On the other hand, in the power supply device 1B, the current flowing through the resistor R0 decreases by the amount of the unbalanced current i, so the voltage + Vi generated in the resistor R0 decreases. The voltage + Vi generated in the resistor R0 is such that the divided voltage for the (−) input terminal of the amplifier 4 is lowered by the bias voltage −Vi, so that the output of the amplifier 4 rises and the output control circuit 3 outputs the output current I2. Work to increase.

Therefore, when the current balance is broken such that I1> I2, the power supply device 1A outputs the output current I.
And at the same time, the power supply device 1B operates so as to increase the output current I2, and finally maintains the current balance holding state where the output current I1 = I2, that is, the unbalanced current i = 0. . Of course, when the output current I2 of the power supply device 1B becomes larger than the output current I of the power supply device 1A and the current balance is lost, the unbalanced current i flows in the opposite direction to decrease the output current I2 and at the same time output current I2 decreases. By increasing I1, the current balance state is maintained.

Next, when one power supply device 1B fails and the detection voltage Vi2 becomes 0V, the unbalanced current i is blocked by the diode D2 connected in parallel with the resistor R3, and the power supply device 1B of the power supply device 1B is blocked. It does not flow to the resistors R0 and R3. Since the detection voltage Vi2 becomes 0V, the constant current circuit Ic
2, the current supplied to Ic1 disappears, and the unbalanced current i is the resistance R0, the constant current circuits Ic1 and Ic2, and the diode D1.
And increases by the amount of current supplied from Vi2.
In this case, since the value of the constant current circuit Ic2 and the value of the resistor R0 are set to the predetermined values, the voltage + Vi generated in the resistor R0 of the power supply device 1A increases by a predetermined amount. Since the input voltage to the (−) input terminal of the amplifier 4 also rises by a predetermined amount, the output of the amplifier 4 also drops by a predetermined amount. Therefore, the output voltage V0 of the output control circuit 3 drops only by a predetermined amount. In this way, the decrease in the output voltage V0 can be set to a value that does not cause a problem in specifications.

Further, in this embodiment, since it is not necessary to use an analog switch, the circuit becomes simple.
Moreover, since it is not necessary to detect a failure, the output voltage does not drop instantaneously. Further, since the failure is not detected, the current can be balanced regardless of the failure detection method. FIG. 3 is a diagram showing another embodiment of the present invention.

In this embodiment, each circuit including diodes D1 and D2 and constant current circuits Ic1 and Ic2 is externally attached. In FIG. 3, the diode D1 and the constant current circuit Ic1
The circuit 2A composed of the two power supplies 1A is connected to the outside of the one power supply device 1A, and the circuit 9B composed of the diode D2 and the constant current circuit Ic2.
Is connected to the outside of the other power supply device 1B.

That is, the constant current circuits Ic1 and Ic2 are respectively connected in parallel to the resistor R3, the diode D1 is connected in series to the constant current circuit Ic1, and the diode D2 is connected in series to the constant current Ic2. As shown in FIG.
In the circuit shown in Figure 1, diodes D1 and D2 and a constant current circuit Ic
The conventional circuit can be used as it is by only externally attaching the circuits 9A and 9B composed of 1 and Ic2, and the same effect as the above-described embodiment can be obtained.

FIG. 4 is a diagram showing still another embodiment of the present invention. The present embodiment is an example in which one current circuit is provided when the diodes D1 and D2 and the constant current circuits Ic1 and Ic2 are externally attached to the power supply devices 1A and 1B, respectively. In FIG. 4, the current balance terminals 14, 1 of the power supply devices 1A, 1B
5 are connected by a diode OR circuit composed of two diodes D1 and D2, and one constant current circuit I is provided at the connection point.
c is provided. In this embodiment, the number of circuit components can be reduced and the circuit configuration can be further simplified. It goes without saying that the above-described effects can be obtained also in this embodiment.

In the above embodiment, the current transformer 5 is used for detecting the output current, but the present invention is not limited to this, and means for generating a voltage proportional to an appropriate output current. Can be used. Although the fixed reference power source using the Zener diode ZD has been taken as an example of the reference voltage of the amplifier 4, a stable output voltage is set by changing the reference voltage using a variable reference voltage source. Of course, it may be changed.

Further, the constant current circuits Ic1 and Ic2 are not limited to those shown in FIG.

[0039]

As described above, according to the present invention, even if one of the power supply devices fails, the value of the resistance as the voltage generating means and the value of the low current circuit are appropriately set, so that the output voltage The decrease of can be set to a value that does not cause a problem in specifications . Moreover, since it is not necessary to use an analog switch, the circuit configuration is simplified and the output voltage does not drop instantaneously. Further, it is not necessary to detect the failure, and the current can be balanced regardless of the detection method.

[Brief description of drawings]

FIG. 1 is a diagram showing a parallel balanced redundant operation circuit of the present invention.

FIG. 2 is a diagram showing an example of a constant current circuit.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing still another embodiment of the present invention.

FIG. 5 is a diagram showing a conventional example.

FIG. 6 is a diagram showing another conventional example.

7 is a diagram showing a specific circuit configuration of FIG.

FIG. 8 is a diagram showing still another conventional example.

9 is a diagram showing a specific circuit configuration of FIG.

10 is a diagram showing a configuration example of the output control circuit of FIG.

[Explanation of symbols]

1A, 1B: Power supply device 2: load 3: Output control circuit 4: Amplifier 5: Current transformer 6: Field effect transistor 7: Constant current diode 8: Transistor 9A, 9B: Circuit 14, 15: Current balance terminals R0-R5: resistance D0 to D6: Diode ZD: Zener diode C0: Capacitor Ic1, Ic2, Ic: Constant current circuit I1, I2: Output current V0: Output voltage Vi1, Vi2: Detection voltage + Vi: voltage

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Claims (5)

(57) [Claims] 1. A parallel current balance type redundant operation circuit in which the output sides of a plurality of power supply devices that generate stable outputs are connected in parallel to a load, wherein an input voltage obtained by dividing the output voltage is applied to each of the plurality of power supply devices. And an amplifier that controls the output control circuit so as to obtain a stabilized output according to the difference voltage between the reference voltage and a predetermined reference voltage, and a current detection circuit that detects the output current supplied to the load and the output side of which is interconnected. The amplifier for generating a voltage of a predetermined polarity according to a current from a detection voltage detected by the current detection circuit or a voltage of a predetermined polarity according to an unbalanced current flowing when a difference occurs in the detection voltage Voltage generating means for biasing the input voltage of
And a diode that prevents an unbalanced current from flowing when one of the power supply units fails or a difference occurs in the detection voltage, and when the detection voltage is balanced, Both currents flow, and when there is a difference in the detection voltage, both the unbalanced current and the current reduced by the unbalanced current flow, and when a failure occurs, only the current from one detection voltage flows. A parallel current balance type redundant operation circuit characterized in that a circuit is provided. 2. The parallel current balance type redundant operation circuit according to claim 1, wherein a resistor having a predetermined resistance value is provided in place of the constant current circuit. 3. The parallel current balance type redundant operation circuit according to claim 1, wherein the value of the voltage generating means and the value of the constant current circuit are set so that a drop in the output voltage is a value that causes no problem in specifications. Parallel current balance type redundant operation circuit. 4. The parallel current balance type redundant operation circuit according to claim 1, wherein a circuit including the diode and the constant current circuit is connected to the outside of the power supply device, respectively. Type redundant operation circuit. 5. The parallel current balance type redundant operation circuit according to claim 4, wherein one constant current circuit is connected between the diodes.