Voltage space vector control device and control method for soft start

Abstract

The invention relates to a voltage space vector control device and a voltage space vector control method for soft start. At present, a soft start technology has the problems of high starting current and low starting torque, and frequency converter soft start has the shortcoming of difficulty in the implementation of power frequency switching. A three-phase alternating current power supply is used for supplying power, six electric GTOs (gate-turn-off thyristors) can be reversely connected in parallel, an IGBT (insulated gate bipolar transistor) is adopted for a continuous current circuit, a voltage space vector control circuit is formed under the control of a microcontroller, and a current transformer is used for transmitting a three-phase current signal to the microcontroller for current limiting start and current monitoring. The phases A, B and C of the power supply of a three-phase alternating current asynchronous motor are subjected to alternating current voltage regulation and frequency modulation control under the control of the microcontroller, a voltage space vector control strategy is used for realizing hexagonal flux linkage track control over the alternating current motor, the voltage / frequency ratio is relatively stable, and the stability of main magnetic flux of the motor is ensured.

Description

technical field [0001] The patent of the present invention relates to a voltage space vector control device and a control method for soft starting. Background technique [0002] At present, ordinary soft starters mainly use three-phase thyristors for step-down starting. It uses two thyristors or bidirectional thyristors connected in series and anti-parallel in each phase in the circuit structure, and realizes step-down starting by changing the conduction time of each phase voltage. Ordinary three-phase thyristor step-down soft starter controls the triggering time of six power gates to turn off the thyristor GTO in sequence, and converts the three-phase power frequency AC waveform into image 3 In the middle shaded area, the mains frequency cannot be changed while changing the voltage. This method has two important disadvantages. First, the starting torque is small, and the starting torque of the three-phase AC asynchronous motor is proportional to the square of the starting...

AI Technical Summary

Problems solved by technology

The structure and technology of the frequency converter are complex, the cost is high, and it is not easy to popularize and promote. At the same time, there is a sudden change in current during switching. So far, it is difficult to solve the problem of switching from frequency conversion to power frequency.

[0004] To sum up, the current soft start technology has the problems of large starting current and low starting torque, and the soft start of the frequency converter has the disadvantage that power frequency switching is difficult to achieve

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