Study Of Three-Phase AC Chopper Surge And Its Harmonic Elimination Technology

Three-phase AC chopper regulator uses all controlled switching devices IGBT, and bring the PWM technology to the application of AC voltage regulator. It has a lot of benefits such as fast speed of dynamic response, wide range of linear regulator and high power factor. It will take the place of thyristor phase control AC voltage regulator in medium and small power fields. This paper uses it in asynchronous motor with light load, makes the electrical output torque and load match through regulating the motor terminal voltage. So it can enhance efficiency, achieve energy-saving purposes. But chopper regulator control system can produce harmonic, cause additional loss, the motor heat, power grid voltage distortion, and other hazards. Active power filter using modern power electronics technology, digital signal processing technology and advanced control theory can dynamic compensate harmonic which is produced by system, and improve the output wave of the voltage regulation circuit.This paper designs the hardware circuit of chopper regulator energy-saving system. It includes main circuit composed by IGBT module and power diodes, control circuit chose TMS320LF2407 DSP chip as the core, micro chip EXB840, and the improved drive circuit based on recommended external circuit. Through the simulation of main circuit by SIMULINK, we prove the feasibility of chopper regulator supply system for light-load motor.We study the development of instantaneous reactive power based on the principle of harmonic detection, and bring a improved ip-iq algorithm which use average value mode instead of LPF. And we bring a new harmonic detection method base on relevant principles and the spectrum move principles. As the result of simulation comparison, harmonic detection algorithm of improved ip-iq algorithm and spectrum move principles has good effect on dynamic response, detection accuracy and so on.We introduce the principle structure of parallel APF and the building of simulate model in the round. By using spectrum move principles to complete harmonic detection of chopper regulator system and hysteresis control strategy to achieve the tracking control of compensated current, bring a method based on current limit control and DC voltage establishing. Through the results of simulation, we can see the parallel APF can compensate the harmonic components caused by chopper regulator's output; the DC voltage can be built successfully; and the whole system have a better reliability. In addition, we also prove the agility of the compensation through the simulation, it can eliminate the reactive power produced by motor load at the same time.