JPS6145755Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a thyristor Serbius device that implements measures against instantaneous power outages.

Thyristor devices such as Thyristor Leonard and Thyristor Servius have recently become larger and have become more public and important, so 0.3
In the event of a momentary power supply disturbance such as a second or 0.5 second (for example, a complete power outage or an open phase power outage), it has become important to continue operation without any problems, and in particular, it is important to constantly reverse convert the thyristor device, such as Thyristor Serbius. For devices used in the field, it is absolutely necessary to detect a power outage in that cycle, perform gate control, and immediately reduce the current to zero; otherwise, commutation failure may occur, leading to an accident.

This idea uses a thyristor Cerbius device to quickly reduce the current in the event of a power disturbance such as a momentary power outage, preventing commutation failure, and automatically transition to normal Cerbius operation when power is restored.
In particular, the purpose is to protect the thyristors and current-limiting resistors necessary for the above-mentioned current reduction, and to immediately stop Serbius operation in the event of damage to these current reduction devices, to take every possible measure to prevent damage to the main circuit thyristors. A detailed description will be given below based on the illustrated embodiment.

The drawing is a circuit configuration diagram of the embodiment, in which 1 is 3.
Phase-wound linear induction motor, 2 is a starting resistor, 3 is a static power return device that returns the induction motor secondary power to the power supply side, which constitutes the main circuit of the thyristor Serbius device, and converts the motor secondary output into DC power once. a forward converter 4 that converts the DC power into AC power, a DC reactor 5 that smoothes the DC power, converts the DC power into AC power at the power supply frequency, adjusts the commutation advance angle, and returns the DC back electromotive force after changing it. It consists of an inverter 6 which determines the amount of power and controls the speed of the motor. 7 is inverse converter 6
This is a transformer inserted between the AC power source and the AC power source to make the AC voltage low enough to allow phase shift control.
It comprises contactors 9, 10, 11, and 12 which are respectively inserted between the starting resistor 2 side and the secondary power return device 3 side, and between the AC power source of the transformer 7, and constitutes a general thyristor Serbius device. .

This invention utilizes the forward converter 4 that converts the secondary power generated by the motor of the Thyristor Cervius device into DC power as a part of a surge absorber that absorbs secondary abnormal power during momentary power outage, and also uses the absorber circuit The system is equipped with various detectors, and if an abnormal current exceeding a specified value flows, Cerbius operation is immediately stopped to prevent damage to the main circuit thyristor (inverter thyristor). From each AC side phase of the converter 4 to the rectified current outflow side group or inflow side group of the forward converter 4, a series path of parallel connected thyristors 13, 14, 15 and current limiting resistor 21 corresponding to each phase, When there is a power disturbance, these thyristors 13, 14, and 15 are ignited and the rectified current of the forward converter 4 is connected to the inflow side group 4b or the outflow side group 4a.
At the same time, fast-acting fuses 16, 17, and 18 are inserted between the secondary side of the induction conductor and the connection points of the thyristors 13, 14, and 15 of each phase on the AC side of the forward converter 4. , immediately detecting a short circuit accident of the thyristors 13, 14, 15,
Alternatively, thermal relays 19 and 20 may be connected in series to any two circuits of thyristors 13, 14, and 15 to detect short-circuit currents that rise relatively slowly and do not cause instantaneous activation of fast-acting fuses 13, 14, and 15. In addition, the thyristors 13, 14 are equipped with a short-circuit current time limit detection device 22 that detects when the conduction time of the current-limiting resistor 21 has reached a certain time limit.
15 or a current exceeding a certain time period due to failure of their gate circuits, these quick-break fuses 13, 14, 15, thermal relays 19, 20,
The contactor 1 is activated by the current time limit detection device 22.
This is to stop Servius operation such as opening of circuits 1 and 12.

That is, when a power supply disturbance such as a complete power outage or an open phase power outage occurs, abnormal power is generated on the secondary side of the induction machine 1, and this must be quickly absorbed to reduce the current to zero. The present invention is based on each phase of the AC circuit on the secondary side and the current inflow side group 4b of the forward converter 4.
(Example shown) Thyristors 13, 14, 15 are connected in parallel and a current limiting resistor 21 is connected in series between them, and a power outage detector (not shown) is used when there is a power supply disturbance such as an open phase.
thyristor 13, 1 by the detection signal from etc.
4, 15, and the thyristors 13, 14,
15 and the current inflow side group 4b of the forward converter 4, a short circuit is formed to immediately absorb abnormal power generated in the motor secondary.

On the other hand, on the inverter 6 side, its phase is shifted to the hard pulse position at the same time as the power supply abnormality occurs.
Only the energy stored in the DC reactor 5 of the DC intermediate circuit is regenerated using the remaining power supply voltage and brought to zero. As a result, the current of the inverter 6 is reduced by the secondary circuit of the motor 1
5. Since it is separated by the surge absorber consisting of the series circuit of the current limiting resistor 21 and the current inflow side group 4b of the forward converter 4, it immediately becomes zero. When the current of the inverter 6 becomes zero, the gate signal at the kick pulse position is removed, but the gate signals of the surge absorber thyristors 13, 14, and 15 remain as they are, and the power is restored when the power supply disturbance ends. Wait until the secondary abnormal voltage is absorbed and then remove it. When the gate signal is removed, the thyristors 13, 14, and 15 are automatically turned off because they are connected to the AC circuit, and the absorber circuit is disconnected from the main circuit. If it is restored and control is resumed, Servius operation will continue.

In addition, it is quite possible that the thyristor groups 13, 14, and 15 of the surge absorber circuit may be damaged by the abnormal output of the motor secondary, and in that case, it is necessary to immediately stop the Servius operation and protect the main circuit thyristors. is necessary.

Therefore, the present invention inserts fast-acting fuses 16, 17, 18 into the current path of the absorber circuit, or connects thermal relays 19, 20, and
5 is detected to prevent damage to other healthy elements and the current-limiting resistor 21, and to stop the Servius operation by opening the contactors 11 and 12. That is,
When the power supply is disturbed, the current flowing through the absorber thyristors 13, 14, 15 is transferred from the secondary side of the electric machine via the contactor 11 to the thyristors 13, 14, 15.
5. The normal current returns to the contactor 11 and the motor secondary side via the current limiting resistor 21, the forward converter 4 current inflow side group 4b, and the thyristors 13, 14, 1.
5 or when the control circuit is damaged, there is an abnormal current, and the present invention detects this abnormal current, immediately shuts off the circuit, and prevents the influence on other healthy elements. For example, thyristor 13,
If either of 14 and 15 becomes conductive in both forward and reverse directions, causing current to flow in the opposite direction, motor 2
The specific phase on the next side is short-circuited by these thyristors, and an abnormally large current flows.In order to detect this, the quick-blow fuses 16, 17, and 18 are
It is connected between the secondary side of the electric motor and the AC side of the forward converter 4, in front of the connection points of the thyristors 13, 14, and 15. In other words, in the case of the above thyristor short circuit accident,
Immediately, the fast-acting fuses 16, 17, and 18 operate to protect other healthy elements and the current-limiting resistor 21 from the abnormally large current, and also to open the contactors 11 and 12, thereby halting the Servian operation. In addition,
However, when the secondary power of the motor is small, such as when the motor is under high speed and light load, a short circuit accident in thyristors 13, 14, and 15 will not cause the abnormal current to rise as sharply as on the left.
It is possible that the protection provided by the quick-acting fuses 16, 17, 18 may be insecure, and in such a case, thermal relays 19, 20 may be inserted into any two circuits of each thyristor 13, 14, 15. In addition, if any of the thyristors 13, 14, and 15 remains in a conductive state similar to a diode due to damage to the element itself or the control circuit, the thyristor and current-limiting resistor 21 remain in a conductive state similar to a diode even after power is restored. ,
The abnormal current continues to flow through the forward converter current inflow side group 4b, and current detection in this case can be easily performed by detecting the time limit of the current flowing through the current limiting resistor 21. In other words, the normal current flowing during a momentary power outage generally lasts about 0.2 seconds or less, and if the current continues to flow for longer than that, it can be assumed that some kind of abnormality has occurred (element failure, gate circuit failure). At both ends of resistor 21,
It is equipped with a short-circuit current time limit detection device 22 that detects the flow of current for a certain time period or more, and when the device 22 operates, the short-circuit current time limit detection device 22 detects the passage of current for a certain time period or more.
All you have to do is stop Servius operation.

In the illustrated embodiment, the current inflow side group 4b of the forward converter 4 is used as a surge absorber circuit, but of course each thyristor is connected with opposite polarity to form a short circuit with the current outflow side group 4a. However, there is no difference in their action or effect. Further, reference numerals 23, 24, and 25 indicate quick-blow fuses for each branch, and the fast-blow fuses 16, 17, and 18 of the absorber circuit and the fast-blow fuse 23 may be inserted into the motor secondary power supply line in common.

As mentioned above, this idea utilizes either the current outflow side or inflow side group of the forward converter in the thyristor Servian device, and creates a short circuit between it and the three attached thyristor groups in the event of a momentary power failure. Abnormal power generated on the secondary side of the motor is absorbed by the short circuit of the thyristor and forward converter diode group, and a fast-acting fuse or even a thermal relay is installed to detect failure of the elements forming the short circuit. , is inserted into the path of abnormal current caused by the failure of this element, and the activation of these fast-acting fuses and thermal relays immediately stops Serbius operation to prevent damage to the current-limiting resistor and inverter thyristor. It detects the time limit of the current flowing to the resistor, and if it exceeds the set value, it is judged as an element failure and, like the above, Cerbius operation is stopped.In the event of a failure in the surge absorber circuit, abnormal current is detected using a "quick blow fuse". Alternatively, the most reliable and reliable device called a "thermal relay" is used to immediately stop Cerbius operation, lowering the current rating of the main circuit thyristor, and preventing abnormal current from flowing to the current limiting resistor. Since the circuit is configured as shown in FIG.

[Brief explanation of the drawing]

The drawing is a circuit configuration diagram of an embodiment. 1...Wound induction conductor, 2...Secondary resistor,
3 ...Motor secondary power return device, 4...Forward converter, 4a...Forward converter current outflow side group, 4b
... Forward converter current inflow side group, 6 ... Inverse converter, 13, 14, 15 ... Thyristor, 16, 1
7, 18...Fast fuse, 19, 20 thermal relay, 21... Current limiting resistor, 22... Short circuit current time limit detection circuit.

Claims (1)

[Scope of utility model registration request] In a thyristor Servius device, a series path in which a current-limiting resistor is connected to a parallel-connected thyristor corresponding to each phase is connected from each phase on the AC side of the forward converter to the rectified current outflow group or inflow side of the forward converter. When the power supply is disturbed, these thyristors are activated to form a short circuit between the rectified current outflow side group or inflow side group of the forward converter, and also to connect the induction motor secondary side and each phase of the forward converter AC side. Insert a fast-acting fuse between the front of the thyristor connection point, connect a thermal relay in series with the two-phase thyristor of the above-mentioned thyristors, and further set the time limit for the conduction current of the current-limiting resistor in parallel with the above-mentioned current-limiting resistor. 1. A thyristor Cervius device, characterized in that a short circuit current time limit detection circuit is connected thereto, and the Cerbius operation is stopped by the activation of these quick-break fuses or thermal relays, as well as the short circuit current time limit detection circuit.