JP2006271080A - Power supply system and input current balancing control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply system and an input current balancing control method capable of reducing a burden on power supply equipment by relieving a current imbalancing state on input power supply side caused by failure in one power supply unit during n+1 redundant operation, in a power supply system for supplying electric power to a load by connecting power supply units of equivalent quantity (at least two) between respective phases with a three-phase AC power supply as an input and by connecting the output in parallel. <P>SOLUTION: This power supply system, which supplies electric power to a load by connecting power supply units of at least two and equivalent quantity between the respective phases with the three-phase AC power supply as an input and by connecting the output in parallel, includes a current controller for controlling an output current so that output balancing of the power supply units between the respective phases may be maintained evenly. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

    The present invention relates to a technical field such as a power supply system that uses a three-phase AC power supply as an input, connects an equal number of power supply devices between phases, and connects the outputs in parallel to supply power to a load.

In a power supply system that receives three-phase alternating current, a configuration is known in which a single-phase power receiving power supply device is evenly connected between phases and operated in parallel. The power supply device has an n + 1 redundant configuration, and operation is continued even when one unit fails. When one power supply device fails, the input current balance between the phases is lost, and an imbalance of the three-phase input current occurs. In view of this unbalanced state, the capacity of the overcurrent protector and the equipment power supply is obtained in view of the design, so that a larger current capacity is required than the actual power consumption. Also, when the three-phase line current imbalance is large, it is necessary to pay attention because it may cause stress on the transformer of the equipment.

  For example, Patent Document 1 discloses a technique for positively operating an overcurrent protector when an input current imbalance is detected.

For example, Patent Document 2 discloses a technique for suppressing the power supplied to the load by preventing the overcurrent protector from working when the input current is unbalanced and an increase in the line current is detected. Yes.
Japanese Patent Laid-Open No. 05-030644 JP 2002-153073 A

  However, any of these conventional techniques has a function to reduce or cut off the current after detecting the unbalanced state of the line current, and to suppress the line current unbalanced state itself. Absent.

  The present invention has been made in view of the above points. A three-phase AC power supply is used as an input, an equal number of power supply devices (two or more) are connected between each phase, and the outputs are connected in parallel to a load. In a power supply system that supplies power, when n + 1 redundant operation is performed, it is possible to alleviate the current unbalanced state on the input power supply side that occurs due to the failure of one power supply device, and to reduce the burden on the power supply equipment. It is an object to provide a power supply system and an input current balancing control method.

  In order to solve the above-mentioned problem, the invention described in claim 1 has a three-phase AC power supply as an input, connects two or more and equal number of power supply devices between each phase, and connects the outputs in parallel. A power supply system that supplies power to a load includes a current control unit that controls an output current so that an output balance of a power supply device between phases is equalized when an imbalance of input current occurs.

  According to a second aspect of the present invention, in the power supply system according to the first aspect, the unbalance of the input current occurs due to a dropout of at least one of the power supply devices, and the current control unit includes: Control is performed so that the output of the power supply device in phase with the dropped power supply device is higher than the output of the power supply device of another phase.

  The invention according to claim 3 is an input current balancing control method in a power supply system in which a three-phase AC power supply is input, an equal number of power supply devices are connected between each phase, and the outputs are connected in parallel to supply power to a load. Then, when an imbalance of the input current occurs, the output current is controlled so that the output balance of the power supply device between the phases becomes equal.

  According to the present invention, even if one of the power supply devices having a redundant operation configuration fails and a current unbalance occurs on the three-phase input side, the unbalance rate can be suppressed, and the line current Can be prevented from becoming large. Therefore, an excessive overcurrent protector and power supply equipment are not required.

  Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. The following embodiment is an embodiment when the present invention is applied to a power supply system.

  First, with reference to FIG.1 and FIG.2, the structure and function of the power supply system which concern on this embodiment are demonstrated.

  FIG. 1 is a diagram illustrating a schematic configuration example of a power supply system, and FIG. 2 is a diagram illustrating a connection example of a power supply device.

  As shown in FIG. 1, the power supply system S includes power supply devices (power supply units) 1 to 6 that have a three-phase AC power supply 9 as an input, and a current control unit 7. As shown in FIGS. 1 and 2, two of these power supply devices are connected between each phase of a three-phase alternating current.

  Each of the power supply devices 1 to 6 includes a main power supply circuit 11, an output current adjustment circuit 12, and an output abnormality monitoring circuit 13. The output lines of the power supply devices 1 to 6 are connected in parallel and connected to the load device 10, and the outputs of the power supply devices 1 to 6 are supplied to the load device 10.

  The current control unit 7 includes a current balance control circuit 14 and controls the output currents of the respective power supply devices 1 to 6 so as to be evenly balanced.

  Further, each of the power supply devices 1 to 6 and the current control unit 7 are connected by a power supply control bus I / F (interface) 8.

  Next, the operation of the power supply system will be described with reference to FIGS.

  FIG. 3 is a diagram illustrating a state of load sharing of the power supply apparatuses 1 to 6.

  As shown in FIG. 2, when two single-phase input power supply devices 1 to 6 are arranged between three-phase alternating current phases and operated with outputs connected in parallel, in a normal state, as shown in FIG. As shown, the sharing of the output current of each of the power supply devices 1 to 6 is controlled by the current control unit 7 to be equal.

  For example, when the power supply device 6 fails, the power supply is continued by the remaining five power supply devices 1 to 5, and the output is equally shared by the five devices as shown in FIG. The At this time, since the current of each phase is 2: 2: 1, a large unbalance occurs in the line current in the three-phase input. In this case, in the three-phase alternating current, the line current increases by one line.

  At this time, the current control unit 7 controls the output current so that the output balance of the power supply devices 1 to 5 between the phases is equal. For example, as shown in FIG. The power supply device 5 having the same phase as the device 6 re-adjusts the sharing to a higher output, and the power supply devices 1 to 4 of the other phases readjust the output to a lower output. That is, the current control unit 7 performs control so that the output of the power supply device 5 in phase with the dropped power supply device 6 is higher than the outputs of the power supply devices 1 to 4 in other phases. Thereby, the current ratio of each phase becomes smaller, and the unbalance rate of the line current can be reduced.

  As described above, by adopting the input current balancing control method of the present invention, one of the power supply devices having a redundant operation configuration fails and a current unbalance occurs on the three-phase input side. However, the unbalance rate can be suppressed, and an increase in the line current can be prevented. Therefore, an excessive overcurrent protector and power supply equipment are not required.

  Note that the current balance function of the current control unit 7 is not affected by any circuit system, and the I / F specification between the power supply devices is not affected by any communication system such as serial / parallel. There is no restriction on adding the function of the present invention.

It is a figure which shows the example of a schematic structure of a power supply system. It is a figure which shows the example of a connection of a power supply device. It is a figure which shows the mode of the load sharing of a power supply device.

Explanation of symbols

1-6 Power supply device 7 Current control unit 8 Power supply control bus I / F
9 Three-phase AC power supply 10 Load device 11 Main power supply circuit 12 Output current adjustment circuit 13 Output abnormality monitoring circuit 14 Current balance control circuit S Power supply system

Claims (3)

In a power supply system that uses a three-phase AC power supply as an input, connects two or more power supply devices between each phase, and connects the same number of power supply devices in parallel to supply power to the load.
What is claimed is: 1. A power supply system comprising: a current control unit that controls an output current so that an output balance of a power supply device between phases is equal when an input current imbalance occurs. The power supply system according to claim 1,
The imbalance of the input current is caused by a drop of at least one of the power supply devices,
The current control unit performs control so that an output of a power supply device in phase with the dropped power supply device is higher than an output of a power supply device of another phase. An input current balancing control method in a power supply system in which a three-phase AC power supply is an input, an equal number of power supply devices are connected between each phase, and the outputs are connected in parallel to supply power to a load.
An input current balancing control method comprising: controlling an output current so that an output balance of a power supply device between phases is equal when an input current imbalance occurs.

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