JPH03107371A - Ac switch - Google Patents

Abstract

PURPOSE:To lengthen the service life of a rectifier circuit by leading out two lines respectively from different phases of three-phase AC power supplies, performing single phase full-wave rectification, connecting the DC section thereof and providing input to a control power supply. CONSTITUTION:Two lines are led out respectively from different phases of three-phase AC power supplies 1a, 1b. A single phase rectifier circuit 3a for two lines of the three-phase AC power supply 1a is connected with the DC section of a single phase rectifier circuit 3b for the two lines V2-W3 of the power supply 1b, and the power is smoothed through a capacitor C4. The smoothed power is fed through a DC/DC converter 5 to a control circuit 6 as a control power supply input. Since the single phase rectifier circuits 3a, 3b having different phases are constituted such that the phases of the peaks in respective single phase rectifier circuits 3a, 3b are different, current is fed at respective peaks. Consequently, it is not possible that only one of the rectifier circuits 3a, 3b feeds current. By such arrangement, current balance can be improved in the rectifier circuits 3a, 3b and the service life thereof is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an alternating current switch with multiple controlled power inputs in an uninterruptible current device.

[Conventional technology]

The control power supply for conventional uninterruptible power supplies is based on the control power supply of uninterruptible power supplies, as described in the 1986 research report on uninterruptible power supplies (Institute of Energy Engineering, Uninterruptible Power Supply Study Group). The control power supply is uninterruptible, so
The inputs of commercial AC power and battery power are duplicated. For the AC switch of a large 3-phase uninterruptible power supply, for reasons of uninterruptible maintenance, the AC switch must be separated from the ground system elements such as the inverter and battery. As shown in FIG. 2, a three-phase AC power supply 1a, for example, direct current obtained by rectifying a commercial power supply by a rectifier circuit 3a', and another three-phase AC power supply 1b, for example, a rectifier circuit 3b' for rectifying the output of an inverter.
Connect the rectified DC and smooth it with capacitor 4,
The DC/DC converter 5 provided uninterrupted control power for the control circuit 6.

[Problem to be solved by the invention]

The above conventional technology uses three-phase full-wave rectification, so there are variations in the power supply voltage. Due to component variations in the 1st current circuit, control power is often always supplied from one of the rectifier circuits, and no consideration is given to balancing the current in the rectifier circuits, resulting in the problem of shortening the life of the rectifier circuit. there were.

The present invention aims to improve the current balance of a rectifier circuit and extend the life of the rectifier circuit.

[Means to solve the problem]

The above object is achieved by drawing out two wires of different phases from each three-phase AC power source, performing single-phase full-wave rectification, and connecting the DC portion thereof to input the control power source.

[Effect]

As mentioned above, the configuration of butting single-phase rectifier circuits with different phases (because the phase of the wave height of each single-phase rectifier circuit is different, current flows in the portion of each wave height, so only one of the rectifier circuits is used) , does not supply current.

〔Example〕

FIG. 1 shows an embodiment according to the present invention. In the figure,
la and lb are three-phase AC power sources, and correspond to, for example, a commercial power source and an inverter output.

The three-phase AC power supply is connected to an AC switch 2, and its control circuit 6 switches the AC switch 2 to 1a or 1.
Power is supplied to the load 7 from b.

The input of the DC/DC converter, which is the control power source of the control circuit 6, is a single-phase rectifier circuit 3a that rectifies the 2-wire U 1-V 1 of 1a, and a single-phase rectifier circuit that rectifies the 2-wire V 2-W Z of lb. The DC part of the circuit 3b is connected and smoothed by the capacitor 4. In this way, by obtaining control power input from different three-phase AC power supplies, the control power supply of the AC switch is made uninterruptible.

Note that if both the three-phase AC power supplies 1a and 1b are out of power, the control circuit 6 loses power, but at this time, there is no three-phase AC power supply that supplies power to the load at the same time, so no problem occurs.

The operation of this embodiment will be explained with reference to FIG. Since the three-phase AC currents gLa and lb are generally synchronized in an uninterruptible power supply, the phases of ULVL of 1a and Vx-Ws of 1b are as shown in FIG. 3(a).

Therefore, the voltage Vc of the smoothing capacitor 4, which is the output of the single-phase rectifier circuits 3a and 3b, ie, the input of the DC/DC converter 5, becomes as shown in FIG. 3(b). Therefore, the currents flowing through the single-phase rectifier circuits 3a and 3b are (
As shown in Q) and (d), the current balance is approximately 1:2.
It will not flow from only one side.

In this embodiment, if voltage accuracy of the control power source is not particularly required, the DC/DC converter 5 can be omitted. Furthermore, if insulation and voltage transformation are not required in the single-phase rectifier circuit, the single-phase transformers 8a and 8b can be omitted. Moreover, a reactor or a resistor may be inserted into the single-phase rectifier circuits 3a and 3b to reduce voltage ripple.

FIG. 4 shows another embodiment according to the invention. This embodiment has three systems of three-phase AC power supplies in FIG. 1, and corresponds to, for example, a configuration of three uninterruptible power supply units in a row.

In this configuration, the single-phase rectifier circuits 3a, 3b, 3c are
Each three-phase AC power supply, 1 a (7) Ux-Vlt
1 b (7) Vz-W211 c (7) Wa-Uδ
Since the phase of the wave height of each single-phase rectifier circuit is different, the current Ia, Ib = Ic of each single-phase rectifier circuit is as follows: Ia: Ib: Ic"1: 1:
1 and balance.

〔Effect of the invention〕

According to the present invention, the control power source of the AC switch can be made uninterruptible with a simple circuit configuration, and the multiplexed DC input of the control power source can be configured. The balance of each single-phase rectifier circuit is 1:2 in the case of duplexing, and 1:1 in the case of triplexing.
1, so the load factor of the rectifier circuit can be averaged without being concentrated on one rectifier circuit, which can extend the life of the control power supply circuit and improve the reliability of AC switches. can do.

[Brief explanation of drawings]

1 and 4 are diagrams showing an embodiment according to the present invention, FIG. 3 is a diagram explaining its operation, and FIG. 2 is a diagram showing an example of an AC switch according to the prior art. la, lb, lc...three-phase AC power supply, 2...AC switch, 3a, 3b, 3c-single-phase rectifier circuit, 3a3b'...three-phase rectifier circuit, 4...capacitor, 5...Figure 1 Figure 1 Figure C

Claims (1)

[Claims] 1. In an AC switch with multiplexed control power inputs in an uninterruptible current device, from each three-phase AC power supply,
An AC switch characterized by drawing out two wires of different phases, performing single-phase full-wave rectification, and connecting the DC part thereof to input control power.