JPS6318967A - Controller for cycloconverter - Google Patents

Abstract

PURPOSE:To enhance the reliability of a system which includes a cycloconverter by bypassing a thyristor converter or a transformer which is defective to sepa rate it from the system, and controlling to continuously supply a balanced polyphase voltage to a load in the remaining active phase. CONSTITUTION:When 3 phases are active, the voltages of R-, S-and T-phases are held in balance at phase difference of 120 deg., and the output voltages of thyris tor converters 4R, 4S, 4T of the phases are controlled so that the amplitudes of the voltages are the same. For example, when the T-phase becomes defective, the output of the T-phase converter 4T is first bypassed by a bypass switch 6T by a defect signal from a defect detector, the output voltages of R-and S-phase converters 4R, 4S are controlled simultaneously, and a balanced 3-phase voltage is supplied to a load 5.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a control device for a cycloconverter, and particularly to a control device for a polyphase cycloconverter used to control the speed of an induction motor, etc. The present invention relates to a microconverter control 2t1M position suitable for use.

(Conventional technology) FIG. 4 shows a well-known three-phase one nicroconverter.

As shown in the figure, AC power supplied from an AC power supply 1 is transmitted from a common circuit breaker 2 to a transformer 3R for each phase.

38. Through 3T, each phase is connected to iristor converter 4R,
48, 4T, is converted into variable voltage, variable frequency three-phase alternating current, and is supplied to the load 5.

Note that the symbols R, S, 'r, and N represent the output phase and neutral point of the three-phase alternating current.

In such a depiction, if, for example, four T-phase 1-Nyristor converters fail, the circuit breaker 2 is generally opened to eliminate this failure. As a result, the entire three-phase cycloconverter stops, making it impossible for the negative section 5 to continue operating. Alternatively, even if you ignore the failure and try to continue operating the three-phase cycloconverter, the output voltage of phase 1 is not healthy, so an unbalanced voltage is applied to load 5, as shown in the vector diagram in Figure 5. There is a risk that the load 5, which is susceptible to unbalanced voltage, may be damaged.

(Problems to be Solved by the Invention) As described above, in the conventional three-phase microconverter J3, a failure of the thyristor converter for one phase spreads to the failure of the entire system, reducing the reliability of the system. It had the disadvantage of low noise.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a cycloconverter control device that solves the problems of the prior art described above, enables continued operation even if one phase of a multiphase cycloconverter fails, and improves the reliability of the cycloconverter. It's about doing.

C Structure of the Invention] (Means for Solving the Problems) The control II device of the present invention is provided corresponding to each phase of a multiphase cycloconverter, and detects a failure in the phase and generates a failure signal. means for bypassing the faulty phase of the multiphase cycloconverter based on the fault signal; and a bypass switch provided for each phase to bypass the faulty phase of the multiphase cycloconverter based on the fault signal; The invention is characterized in that it further includes a control means for controlling the voltage so that a balanced voltage is generated.

(Function) According to the present invention, even if one phase of the cycloconverter fails, this phase can be bypassed and the converter of the other phase can continue to supply balanced voltage to the load. The converter can continue to operate.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a control device for a nicro converter according to an embodiment of the present invention, and FIG. 2 is a block diagram of a control section applied to the configuration of FIG. 1. In addition, the circuit breakers 2R, 28, and 2T are connected to the transformer 3R for each phase of RlS and T.
, 33, 3T. On the other hand, thyristor conversion Z4R.

Bypass switch 6R to bypass 48.4T
, 63, 67 are provided, and the thyristor converters 4R, 43
, 4T from the load 5.
, 78, 7T are provided.

On the other hand, in FIG. 2, there is J3, for example, the T-phase failure detection circuit 8.
detects a failure in the T-phase transformer 3T or four thyristor converters and sends a failure signal a. Signal inversion circuit 9
G and S phase reference voltage v8o are inverted. Control angle determining circuit 1
0 determines the S-phase control angle αS based on the deviation between the reference voltage v3o or its inverted voltage and the S-phase output voltage VSN, and sends it to the thyristor converter 4S.The first delay circuit 11A is faulty. The signal a is delayed and a circuit breaker opening signal S is sent to the circuit breaker 27.The second delay circuit 11B further delays the circuit breaker opening signal S and sends a fil release signal C to the disconnection switch 7T. Note that the failure signal a is also used as an input signal for the six bypass switches.

In such a configuration, the operation will be explained in FIGS. 3(A) and 3(B), taking as an example the case where the thyristor converter 4T or three transformers of phase 1 fails.

This will be explained with reference to the Betar diagram in (C).

Now, if all three phases are healthy, as shown in Figure 3 (A), each phase maintains a phase difference of 120° so that the voltages of the R, S, and T phases are balanced, and the voltage The reference voltages ■Ro, ■ as shown in FIG. 3(C) are set so that the magnitudes are the same.
8o, ■1o, thyristor conversion of each phase B4R,4
Controls the output voltage of S and 4T.

On the other hand, if the phase ■ fails, the outputs of the four T-phase thyristor converters are first bypassed by the bypass switch 6 in response to the failure signal a from the failure detection circuit 8, and at the same time, as shown in FIG. As shown in (B), the output voltages of healthy R and S two-phase thyristor converters 4R and 43 are controlled.

For this purpose, the S-phase reference voltage ■8o is determined by the fault signal a.
The signal inverting circuit 9 inverts the polarity of the signal and inputs the signal to the control angle determiner "t810. As a result, the S-phase output voltage vSN is inverted by the S-phase control angle α,
The output voltage can be controlled 211 as shown in FIG. 3(B).

By controlling the three-phase cycloconverter in this manner, even if one phase fails, a balanced three-phase voltage can still be supplied to the load 5.

Note that by performing such control, the variable frequency range of the cycloconverter itself is narrowed, and when an inductor is connected as load 5, the efficiency will decrease slightly, but the worst case of system failure can be avoided. can.

Furthermore, the circuit breaker opening signal obtained by delaying the failure detection signal a in the delay circuit 11A opens the faulty T-phase AC side circuit breaker 2, and further transmits this circuit breaker opening signal to the delay circuit 11A.
If the 7 disconnection switches are opened by the disconnection switch open signal C delayed by B, and the transformer 3T and 4 thyristor converters of phase 1 are turned off, the recovery work of the T phase can be carried out while continuing the operation of load 5. can be done. Furthermore, by following the above-mentioned procedure in reverse after the T-tank is restored, the cycloconverter can again continue to operate in a healthy manner for all three phases.

In the above embodiment, the explanation was given by taking the failure of the phase ■ as an example, but the same control can be performed in the case where the failed phase is the R phase or the S phase. can continue to operate.

In addition, in the above embodiment, the case where the number of output phases of the cyclo[ ] converter is three is explained as an example, and l
It goes without saying that the present invention can be easily applied to a microconverter having a number of output phases greater than the number of output phases.

In addition, if the thyristor converter and transformer of each phase are made to have enough margin to be able to output line voltage, even if one phase is lost, operation will continue without changing the voltage applied to the load at all from the normal state. I can do this.

(Effects of the Invention) According to the present invention, even if the sirisk converter or transformer for one phase of a multi-phase one nicroconverter fails, it can be bypassed and disconnected from the system, and the remaining healthy phase can be used. 1111 that continues to supply balanced multiphase voltage to the load.
By performing 1 all, the reliability of the entire system including the cycloconverter can be improved.

[Brief explanation of drawings]

Fig. 1 is a wiring diagram showing the main circuit configuration of the cycloconverter control device of the present invention, Fig. 2 is a block diagram of the control section applied to the device of Fig. 1, and Fig. 3 (Δ), (B). , (C) is a vector diagram for explaining the operation of the configuration shown in FIGS. 1 and 2, FIG. 4 is a wiring diagram showing the configuration of a well-known cycloconverter, and FIG. FIG. 1 is a vector diagram of the output voltage of the Cyrisk converter when a T-phase failure occurs. 1...AC power supply, 2...breaker, 3...transformer,
4... Cyrisk converter, 5... Load, 6... Bypass switch, 7... Disconnection switch, 8... Failure detection circuit, 9... Signal inversion circuit, 10... Control angle Decision circuit, 11A, 11B...delay circuit. vRO ■TOvSO (C) Tsumugi 3 M Tsumugi 4 fig. 5 fig.

Claims (1)

[Claims] 1. Means provided for each phase of the polyphase cycloconverter to detect a failure in the phase and generate a failure signal; and means provided for each phase to generate a failure signal based on the failure signal. It is characterized by comprising a bypass switch that bypasses the faulty phase of the cycloconverter, and a control means that controls the healthy phases of the multiphase cycloconverter as a whole so that a balanced voltage is generated based on the fault signal. Cycloconverter control device.