JPH05199764A - Dc voltage generator - Google Patents

Abstract

PURPOSE:To minimize a stopping period of power supply and to control the annihilation of ions to the utmost without lowering operation efficiency by changing over constant current control from constant voltage control in the case of a load short circuit. CONSTITUTION:A load short circuit is detected by a load short circuit detection circuit 9 based on load current or output current, and signals from a power control circuit 7 are switched to voltage standard B by a signal change-over switch 16 and are transferred to a power width decision circuit 15. Signals into, which a difference between inverter current and current standard B is converted by a current control circuit 18 is transferred to the power width decision circuit 15 by a signal change over switch 17 through signals from the load short circuit detection circuit 9. As a limiter function of output current of an inverter device 12, signals from a current control circuit 14 are transferred to the power width decision circuit 15 irrespective of a load condition. In the case of the load short circuit, voltage is controlled to value corresponding to the voltage standard B set in necessary value in the case of the load short circuit in advance, and current is controlled to value corresponding to the current standard B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC voltage generator which uses a load such as an ion source that causes many short circuits.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing a conventional DC voltage generator.

The alternating current supplied from the alternating current system to the rectifier 4 through the circuit breaker 1, the alternating current switch 2 and the transformer 3 is converted into direct current, and direct current power is supplied to the load 5. The output voltage detection device 6 connected in parallel to the load 5 detects the output voltage. The AC switch 2 is controlled based on a signal obtained by converting the difference between the output voltage and the output voltage reference by the voltage control circuit 7.

A load short circuit detection circuit 9 detects a load short circuit based on a load current or an output voltage detected by a current detector 8 connected between the rectifier 4 and the load 5. If you know that there is a short circuit,
The semiconductor switching element 10 connected between the rectifier 4 and the current detector 8 shuts off the load 5 to protect the DC voltage generator.

[0005]

Such a DC voltage generator could be realized for an output voltage of about 100 KV, but when a higher voltage of 300 KV or more is required, a load switching semiconductor switching element is used. Since it is necessary to connect a large number of them in series, it becomes expensive and large in size, which is not practical. Therefore, when increasing the voltage above 300 KV,
It has been proposed in the past to provide an inverter device on the low voltage side instead of the AC switch 2 for high-speed switching.

However, in such a DC voltage generator, although protection at the time of load short-circuiting is possible as before, the output voltage is inevitably made zero during the load short-circuiting period, so that the higher the output voltage is, the higher the output voltage becomes. There is a problem that the operating efficiency of the load such as the ion source is deteriorated and the number of ions to be eliminated is increased.

Therefore, the present invention provides a DC voltage generator capable of suppressing the disappearance of ions as much as possible without reducing the operating efficiency of the load, even when a load such as an ion source that causes many short circuits is used as a load. With the goal.

[0008]

In order to achieve the above-mentioned object, the present invention is a thyristor converter for converting alternating current supplied from an alternating current system to direct current, and a direct current converted by this thyristor converter. Inverter device, a transformer for boosting the alternating current output from this inverter device, and a DC voltage generator comprising a rectifier for converting the alternating current output from this transformer into direct current, the output voltage of the rectifier is A constant voltage control circuit for feeding back to the inverter device, a constant current control circuit for feeding back the output current of the inverter device to the inverter device, the constant voltage circuit and the output current circuit It is characterized in that a signal changeover switch for changing over is provided.

[0009]

With the above-mentioned structure, when the load is short-circuited, the constant voltage control is switched to the constant current control, so that the operating efficiency of the load such as the ion source is not reduced.
Ion annihilation can be suppressed to a small extent.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the block diagram of FIG. The same parts as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted.

Electric power is supplied from the AC system to the thyristor converter 11 via the circuit breaker 1, and the thyristor converter 11 converts AC into DC. The power converted into DC by the thyristor converter 11 is converted into AC again by the inverter device 12, boosted by the transformer 3, further converted into DC by the rectifier 4, and then supplied to the load 5.
The output voltage detection device 6 connected in parallel with the load 5 detects the output voltage, and the current detector 8 connected between the rectifier 4 and the load 5 detects the load current. An inverter current is detected by a current detector 13 connected between the transformer 12 and the transformer 3.

During steady operation, the output voltage and the output voltage reference A
After the signal obtained by converting the difference between the voltage control circuit 7 and the signal obtained by converting the difference between the inverter current detected by the current detector 13 and the current reference A by the current control circuit 14 is added, the energization width determination circuit The inverter device 12 is controlled through 15. The energization width determination circuit 15 determines the energization width of the inverter device 12 according to the input signal, and adjusts the value of the output voltage according to the magnitude of the width.

The load short circuit is detected by the load short circuit detection circuit 9 based on the load current or the output voltage. The signal from the load short-circuit detection circuit 9 is switched by the signal change-over switch 16 to the voltage reference B which is preset to a value necessary for load short-circuiting, and the signal is sent to the energization width determination circuit 15. send. Similarly, the load short circuit detection circuit 9
In response to the signal from, the signal changeover switch 17 sends a signal obtained by converting the difference between the inverter current and the current reference B by the current control circuit 18 to the energization width determination circuit 15. or,
The signal from the current control circuit 14 is sent to the energization width determination circuit 15 regardless of the state of the load, and the energization width determination circuit 15 determines the energization width of the inverter device 12.

The voltage reference B input to the energization width determination circuit 15 when the load is short-circuited has a lower potential than the output voltage reference,
It is assumed that the response of the current control circuit 18 is several times to several tens of times faster than the response of the current control circuit 14.
Is for positively performing constant current control, and the current control circuit 14 is used as a limiter function of the output current from the inverter device 12.

With such a configuration, when the load is short-circuited, the voltage has a value according to the voltage reference B which is set to a value required in advance when the load is short-circuited, and the current is limited to a value according to the current reference B. can do.

[0016]

As described above, according to the present invention,
Even if a load such as an ion source that causes many short circuits is used as a load, it is possible to minimize the period of power supply interruption to the load during a short circuit, and to minimize the disappearance of ions without lowering operating efficiency. It is possible to provide a DC voltage generator capable of performing the above.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a DC voltage generator showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional DC voltage generator.

[Explanation of symbols]

1 ... Circuit breaker 2 ... Input switch 3 ... Transformer 4 ... Rectifier 5 ... Load 6 ... Output voltage detection device 7 ... Voltage control circuit 8, 13 ... Current detector 9 ... Load short-circuit detection circuit 10 ... Semiconductor switching element 11 ... Thyristor conversion Unit 12 ... Inverter device 14, 18 ... Current control circuit 15 ... Energization width determination circuit 16, 17 ... Signal changeover switch

Claims (1)

[Claims] 1. A thyristor converter for converting alternating current supplied from an alternating current system to direct current, an inverter device for converting direct current converted by the thyristor converter to alternating current, and an output from the inverter device. In a DC voltage generator comprising a transformer for boosting an alternating current and a rectifier for converting the alternating current output from the transformer into a direct current, a constant voltage control circuit for feeding back the output voltage of the rectifier to the inverter device, A constant current control circuit for feeding back the output current of the inverter device to the inverter device, and a signal changeover switch for switching between the constant voltage circuit and the output current circuit. DC voltage generator.