JP3428242B2 - Uninterruptible power system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention supplies electric power to a load from a commercial power source through a semiconductor switch when the commercial power source is healthy (hereinafter referred to simply as "normal time"), and from a storage battery to an inverter when the commercial power source fails. The present invention relates to an uninterruptible power supply device that supplies power to a load via a power supply.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a conventional example of this type of uninterruptible power supply. In FIG. 4, 1 is a commercial power source,
2 is a storage battery, 3 is a load, 10 is an uninterruptible power supply,
The uninterruptible power supply 10 includes a circuit breaker 11, a semiconductor switch 12, a gate drive circuit 13, an electromagnetic contactor 14, a smoothing capacitor 15, an inverter main circuit 16, a transformer 17, an AC reactor 18, a filter capacitor 19, and a limiting resistor 2.
0, electromagnetic contactors 21 and 22, and an inverter control circuit 23. In addition, the filter capacitor 19
Is a filter that removes switching noise that occurs with the switching operation of the inverter main circuit 16.

The uninterruptible power supply system 10 shown in FIG. 4 operates as follows. First, the circuit board breaker 1
1 is closed, and the semiconductor switch 12 is made conductive by the gate drive circuit 13, so that the commercial power source 1 switches the circuit breaker 11
The power supply to the load 3 is started via the semiconductor switch 12, the electromagnetic contactors 14 and 21 are closed, and the rush current flowing through the smoothing capacitor 15 and the storage battery 2 via the inverter main circuit 16 is suppressed by the limiting resistor 20. After that, the electromagnetic contactor 22 is closed, and the inverter control circuit 23 causes the inverter main circuit 16 to start the charging operation for the storage battery 2 and the active filter operation for absorbing the harmonic current and the reactive current generated from the load 3. The start-up is completed by starting the, and the uninterruptible power supply 10 enters the normal state.

Here, as the active filter operation, the inverter main circuit via the AC reactor 18 is controlled by the gate signal of the output of the inverter control circuit 23 adjusted based on the current of the load 3 detected by the current detector 24. The 16 output AC voltages are controlled. Next, at the time of power failure of the commercial power source 1, a power failure detection circuit (not shown) detects this and the gate drive circuit 13 causes the semiconductor switch 1 to operate.
2, the inverter control circuit 23 supplies power from the storage battery 2 to the load 3 through the electromagnetic contactor 14, the smoothing capacitor 15, the inverter main circuit 16, the transformer 17, the AC reactor 18, the filter capacitor 19, and the electromagnetic contactor 22. To do.

[0005]

According to the above-mentioned conventional uninterruptible power supply, a limiting resistor and two electromagnetic contactors are provided to suppress the excessive inrush current flowing through the semiconductor switch to the inverter side at the time of startup. In addition, a semiconductor switch with a large overcurrent withstand capability was selected on the assumption that the load that inrush current flows would be connected to the uninterruptible power supply. There was also a problem in terms of price.

Further, when the semiconductor switch is ignited, a voltage relay is conventionally provided on the load side of the semiconductor switch to detect it. However, the uninterruptible power supply system due to the delay in detection of the voltage relay. There was also a risk of hindering his function. An object of the present invention is to provide an uninterruptible power supply device that solves the above problems.

[0007]

According to the present invention, when a commercial power source is healthy, power is supplied to a load through a semiconductor switch that supplies / shuts off power from the commercial power source, and an inverter drives the commercial power source to a storage battery. In an uninterruptible power supply system that performs charging operation and active filter operation that absorbs harmonic current and reactive current generated from the load, and supplies power to the load from the storage battery via the inverter when the commercial power source fails A bypass contactor configured by an anti-parallel circuit of a thyristor having a switch for each phase of a commercial power source, a bypass contactor connected in parallel with the semiconductor switch, a line voltage of each phase on the commercial power source side of the semiconductor switch, and the semiconductor switch. The arc-out detection time for detecting the deviation of each phase from the line voltage of each phase on the load side and detecting that this deviation exceeds a specified value. And, when the arcing detection circuit operates, the semiconductor switch is cut off, the load is fed from the storage battery through the inverter for a predetermined period, and the bypass contactor is turned on when the predetermined period is reached. And a control circuit.

Further, in the above, the bypass contactor is provided with an operation control circuit for stopping the active filter operation during the closing period.

[0009]

According to the present invention, a semiconductor switch is formed of an anti-parallel circuit of a thyristor provided for each phase of a commercial power source, and a bypass contactor connected in parallel with the semiconductor switch and a commercial power source side of the semiconductor switch. An arc-extinguishing detection circuit that detects a deviation of each phase between the line voltage of each phase and the line voltage of each phase on the load side of the semiconductor switch, and detects that the deviation exceeds a predetermined value, When the arcing detection circuit operates, the semiconductor switch is cut off, power is supplied from the storage battery to the load through the inverter for a predetermined period, and when the predetermined period is reached, the bypass contactor is turned on, thereby the semiconductor The function as an uninterruptible power supply due to the switch being extinguished is maintained.

Further, in the above invention, the power flow from the inverter side to the commercial power supply is suppressed by stopping the active filter operation during the closing period of the bypass contactor, and the inverter is damaged by the overcurrent as the power flow. Prevent from doing.

[0011]

EXAMPLES In the examples of the present invention described below,
Those having the same functions as those of the conventional example shown in FIG. 4 are designated by the same reference numerals, and the description thereof will be omitted. The functions different from those of FIG. 4 will be mainly described. FIG. 1 is a configuration diagram of an uninterruptible power supply device showing a first embodiment of the present invention.

In the uninterruptible power supply 30 shown in FIG. 1, the semiconductor switch 31 is composed of an antiparallel circuit of thyristors provided for each phase of the commercial power supply 1, and the output signal of the current detector 24 and the uninterruptible power supply not shown. When the start signal of the thyristor 30 is input to the gate drive circuit 32, the ignition phase of the thyristor is adjusted by a known technique when the uninterruptible power supply 30 is started or when the current of the load 3 is about to exceed the rated current. Generated gate signal to generate the semiconductor switch 3
1 prevents overcurrent.

In FIG. 1, the circuit breaker 25 is normally closed, and an overcurrent protection operation that flows into the inverter main circuit 16 from the commercial power source 1 via the semiconductor switch 31 when the inverter main circuit 16 has a short circuit failure is performed. The uninterruptible power supply 30 is opened at the time of maintenance and inspection, for example. FIG. 2 is a configuration diagram of an uninterruptible power supply device showing a second embodiment of the present invention.

In the uninterruptible power supply 40 shown in FIG. 2, the semiconductor switch 31 is composed of an anti-parallel circuit of thyristors provided for each phase of the commercial power supply 1, and a bypass contactor 41 connected in parallel with the semiconductor switch 31 and a semiconductor. Each of the detected value of the transformer 42a that detects the line voltage of each phase on the commercial power supply 1 side of the switch 31 and the detected value of the transformer 42b that detects the line voltage of each phase on the load 3 side of the semiconductor switch 31. An arcing detection circuit 42 for detecting the deviation of the phase of the above with an addition calculator 42c and detecting with a comparator 42e that this deviation exceeds a predetermined value (for example, about 2 volts by 42d in FIG. 2), and an arcing detection. When the circuit 42 operates,
The semiconductor switch 31 is cut off via the gate drive circuit 43, and the inverter control circuit 44 operates so that power is supplied from the storage battery 1 to the load 3 via the inverter main circuit 16 for a predetermined period (for example, about 5 seconds). When the predetermined period is reached, the power supply from the inverter main circuit 16 is stopped,
An arc-extinguishing control circuit 45 for turning on the bypass contactor 41 is provided.

Further, in FIG. 2, the uninterruptible power supply 4
0 means that when the bypass contactor 41 is closed, the active filter operation is stopped in order to cope with the above operation. FIG. 3 is a configuration diagram of an uninterruptible power supply device showing a third embodiment of the present invention. In the uninterruptible power supply device 50 shown in FIG. 3, when the current flowing through the load 3 from the output signal of the current detector 24 tries to exceed the rated current, the contactor control circuit 51 operates and the bypass contactor 41 closes. The current flowing through the bypass contactor 41 prevents the semiconductor switch 31 from being damaged by an overcurrent.

Further, in FIG. 3, the uninterruptible power supply 5
0 means that when the bypass contactor 41 is closed, the active filter operation is stopped in order to cope with the above operation.

[0017]

According to the present invention, when an excessive current is about to flow through the semiconductor switch, the semiconductor switch can be operated by adjusting the firing phase of the thyristor constituting the semiconductor switch or by closing the bypass contactor. Since damage due to overcurrent is prevented, the semiconductor switch becomes smaller, which contributes to lowering the cost of the device.

Further, since it is possible to provide an arc-extinguishing detection circuit for promptly detecting when an arc-out occurs in the semiconductor switch, the reliability as an uninterruptible power supply is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an uninterruptible power supply device showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an uninterruptible power supply device showing a second embodiment of the present invention.

FIG. 3 is a block diagram of an uninterruptible power supply showing a third embodiment of the present invention.

FIG. 4 is a configuration diagram of an uninterruptible power supply device showing a conventional example.

[Explanation of symbols]

1 ... Commercial power supply, 2 ... Storage battery, 3 ... Load, 10, 30, 4
0, 50 ... Uninterruptible power supply, 11 ... Circuit breaker, 12,
31 ... Semiconductor switch, 13, 32, 43 ... Gate drive circuit, 14, 21, 22 ... Electromagnetic contactor, 15 ... Smoothing capacitor, 16 ... Inverter main circuit, 17 ... Transformer, 18
... AC reactor, 19 ... Filter capacitor, 20 ...
Limiting resistors, 23, 44 ... Inverter control circuit, 24 ... Current detector, 41 ... Bypass contactor, 42 ... Arcing detection circuit, 45 ... Arcing control circuit, 51 ... Contactor control circuit.

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-7-163066 (JP, A) JP-A-4-248338 (JP, A) JP-A-7-59274 (JP, A) Actual development 63- 97348 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02J 9/00-11/00 H02J 7/34

Claims (2)

(57) [Claims] 1. When the commercial power source is healthy, power is supplied to the load through a semiconductor switch that supplies / shuts off the power from the commercial power source, and the inverter operates to charge the commercial battery from the commercial power source and generate the load. In an uninterruptible power supply system that performs active filter operation that absorbs harmonic currents and reactive currents, and supplies power to the load from the storage battery via the inverter during a power failure of the commercial power supply, use a semiconductor switch for each phase of the commercial power supply. A bypass contactor connected in parallel with the semiconductor switch, a line voltage of each phase on the commercial power source side of the semiconductor switch, and a line of each phase on the load side of the semiconductor switch. An arc-extinguishing detection circuit that detects the deviation of each phase from the inter-voltage and detects that this deviation exceeds a predetermined value, and the arc-existing detection circuit operates. When this occurs, the semiconductor switch is cut off, power is supplied to the load from the storage battery through the inverter for a predetermined period, and the arc-extinguishing control circuit is turned on to turn on the bypass contactor when the predetermined period is reached. And an uninterruptible power supply. 2. The uninterruptible power supply according to claim 1, further comprising an operation control circuit that stops the active filter operation during the closing period of the bypass contactor.