Research On Repression Method Of Harmonics For High Speed Motor Power Conversion System

The thesis is a part of the project-"The distributed high speed generator system driven by micro-turbines and its energy conversion system",which is supported by the National Natural Science Foundation of China.The high speed generator,for its small volume,high efficiency and great power density,is one of the great concerns in electrical engineering. The high-speed generator is actually a generator/motor.During starting,the machine works as a motor to make the micro-turbine starting since the turbine cannot be self-started. When the turbine can output rated power,the machine will finish motoring operation and begins to work as a generator to output electric power.The high frequency output AC power is converted into constant frequency(50Hz) and constant voltage(380V line to line) through the AC/DC/AC output converter.In order to ensure the output AC power quality,a specially designed Line and EMC(electromagnetic compatibility) filter should be used to filter the harmonic components from the output voltage and current of the PWM(pulse width modulation) output converter.The main work of this paper is how to reduce the harmonic generated by high speed generator system.First of all,the harmonic suppression principle of the phase-shifting transformer specially the phase-shifting rectifier reactor is studied.The selection of optimal phase-shifting angle,structure and connection of phase-shifting windings of the phase-shifting reactor are analyzed.A six-,twelve-phase rectifying system with the phase-shifting reactor is simulated and tested.Both the simulation and the tested results shows that the harmonic suppression of the phase-shifting rectifier reactor is effective.Secondly,an engineering design method of sinewave filter in high frequency transducer is presented based on harmonic characteristics of commonly used modulation techniques and RLC filter equivalent circuits.Discussed the engineering design principles techniques and RLC filter equivalent circuits.Discussed the engineering design principles of the filter parameters.Simulation and experimental results validate the proposed method.Finally,the shunt active power filters are studied and built into models.Based on DSP using ip-iq harmonic detecting method,with double-loop control strategy and SHEPEM modulation strategy,it can eliminate high-frequency harmonics used by active power filters(APF).