JPS60141189A - Thyristor inverter operation protecting circuit - Google Patents

Abstract

PURPOSE:To prevent an overcurrent due to the failure of the operation of an inverter at a power interruption time by breaking a gate pulse to a thyristor at power interruption occurring time and inserting a resistor for limiting a current to a DC circuit. CONSTITUTION:A transistor which becomes the same polarity as a thyristor conducted of transistors 12, 13 inserted into a DC circuit is normally conducted in a normal operation, and the output current of the thyristor is supplied through the transistor to a DC motor 9. When a power interruption is detected by a power interruption detector 10, a gate interruption signal is applied to a gate pulse generator 3 to interrupt a gate pulse to a thyristor. Simultaneously, the both transistors 12, 13 are turned OFF. Thus, a current limiting resistor 14 is inserted into the DC circuit, and an overcurrent can be suppressed when the operation of the inverter is failed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a motor control circuit using a thyristor.

[Prior art]

g < 1 The figure shows motor control i1 using conventional thyristor Q.
The configuration of one circuit is shown. (1) Hasairista Cook, +
21 I'i loop control circuit b6, (3) is a gate pulse generation circuit, a 41tri pulse transformer whose output is connected to the gate of Cyrisk. (51 is a magnetic current detection circuit,
(6) is a voltage detection circuit, (7) is a circuit breaker that prevents an overcurrent of DC 1gl+@, (8) is an overcurrent protection circuit, and (9) is a DC motor.

Next K! I! I will explain about IJ's work. When the control circuit is in normal operation, the gate pulse generation circuit generates a gate pulse with a phase corresponding to the output of the loop control circuit, and the gate pulse is passed through the entire pulse transformer and applied to the forward or reverse direction of the sirisk, resulting in the output voltage of the sirisk.

The current is phase controlled.

When an overcurrent occurs in the thyristor output circuit for some reason, the overcurrent detection circuit VCL detects the overcurrent, a gate cutoff signal is given to the gate pulse generation circuit, and the gate pulse to the thyristor is cut off. If the tripped overcurrent exceeds the circuit breaker's trip current value, the circuit breaker trips, protecting the DC motor and circuit from the overcurrent.

However, in conventional circuits, after an overcurrent occurs, it is detected, the gate is shut off, and the circuit breaker is tripped, so if the inverter operation fails due to a power outage,
The drawback is that an overcurrent similar to an accident caused by another cause occurs, and the control lPl goes into failure mode.Furthermore, in an installation location with poor power supply conditions where instantaneous power outages occur frequently, inverter operation failures may occur again. However, unmanned station numbers had drawbacks such as the difficulty of re-turning on the circuit breaker after the power was restored.

[Summary of the invention]

The object of the present invention is to provide the following circuit in order to eliminate all of the drawbacks of the prior art as described above. When a power outage occurs, instead of detecting the overcurrent that has occurred, the system detects the power outage and thereby cuts off the gate pulse to the thyristor. In addition, when a power outage occurs, power failure detection and 14:11? : A circuit that inserts a current-limiting resistor into a DC circuit.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 2, the same reference numerals as in FIG. 1 indicate the same or corresponding parts. (101 is a power failure detection circuit, (11) is a driver driver, 116, 021 and (13) are forward and reverse bower output transistors, (141 is a current limiting resistor. The power failure detection circuit is a rectifier circuit and a comparison circuit. It can be constructed from circuits.

Next, the operational VC will be explained.

In normal operation, among the transistors inserted in the DC circuit, those transistors having the same polarity as the conducting thyristor are always in a conducting state, and the output current of the thyristor is supplied to the DC motor through all the transistors. When a power outage occurs, a power outage is detected by the power outage detection equal to VC, and the gate cutoff is given to +j to pulse f, and the gate pulse to Cyrisk is cut off. At the same time, the conducting transistor is turned off, and both transistors are turned off. Therefore, if the thyristor is in a conductive state in the inverter mode when a power outage occurs, the current limiting resistor Wt and l will be fully connected and regenerated. The load circuit has a time constant greater than the inductance component of the DC motor, m5ec12.

The circuit breaker also has a time constant of dmsec. Therefore, by completing the operation of the protection circuit within the time when the transient response of the overcurrent reaches the circuit breaker trip value in the circuit/path Vc that has a power outage, the operation will fail overnight during a power outage. Even if this happens, the overcurrent can be completely suppressed without tripping the circuit breaker.

〔Effect of the invention〕

As described above, if this F3AVcL is used, the station is detected, the gate is shut off, and the DCIP! Inserting a current limiting resistor into the circuit has the effect of preventing overcurrent caused by failure of inverter operation during a power outage and distinguishing it from fault current caused by other causes. There are also frequent power outages! Even in installation locations with poor power supply conditions, the circuit breaker will not trip due to inverter operation failure, so it is easy to restart the control circuit after the power is restored, and in unmanned stations, consideration should be given to a means of re-turning the circuit breaker. It has the effect of being unnecessary.

[Brief explanation of drawings]

Figure 11 shows the configuration of a conventional thyristor control circuit, and Figure 2 shows a thyristor that was invented and failed. tl+...Thyristor stack, (2)...Loop+1! II (a circuit, (3)...Gate pulse Q raw 10J m, (4)...Pulse transformer, (5)...
・Toron flow detection circuit, (61...Toron pressure detection circular, 171・
...Circuit breaker, (8)...Supercurrent detection circuit, (9)...D. Motor, I (11...Power failure detection circuit, :11)...
Dry node, t121゜(13)...Switching power transistor, (14)...Current limiting resistor portIn addition, in the figure, 11-sign indicates the same- or equivalent part0 Agent Masuo Oiwa

Claims (1)

[Claims] The Do motor control VC by Cyrisk is equipped with a power failure detection circuit, a gate pulse cutoff circuit, a current limiting resistor connected to the load circuit in series with a VC, and a switching circuit connected in parallel to the current limiting resistor, and a switching circuit is connected in parallel to the current limiting resistor. A thyristor inverter operation protection circuit characterized by inserting a current limiting resistor into a load circuit by completely cutting off gate pulses to and completely turning off the mata switching circuit.