Control Strategy Of High Power Inverter System And Parameter Identification

In the high-voltage and high-power drive system control applications, using multi-leveltechnology can reduce the device’s withstand voltage, reduce the harmonic content of the outputwaveform to improve the quality of the output voltage. In this dissertation, three-level diode-clampedinverter which is widely used in high-voltage and high-power drive system has been studied. Byanalyzing its structure and working principle, the three-level inverter space vector modulation andselective harmonic elimination modulation are introduced. The midpoint potential imbalance isanalyzed and a balanced midpoint potential control methods is presented. The hybrid modulation ofspace vector modulation and selective harmonic elimination modulation is also introduced.In recent years, with the rapid development of high-voltage and high-power drive system, speedsensorless induction motor vector control has become a research hotspot of modern motor drive.Vector control realize decoupling control of the induction motor using coordinate transformationwhich change the high-level, multi-variable, strong coupling of the induction motor system into anequivalent DC motor. This method simplifies the control of induction motor which makes the gainingof the high quality of speed performance of induction motor possible. Speed sensorless vector controltechnology eliminates the speed sensor installation, reducing system cost, realizing a wider range ofapplications. However, an accurate estimate of the motor speed has become an important part of thetechnology. This dissertation analyzes the basic principles of vector control, describes the inductionmotor model reference adaptive control motor speed estimation method, and focuses on the full-orderflux observer for speed sensorless induction motor speed control system.In the vector control AC induction motor drive systems, the parameters of the motor are criticalfor the control of the system. Precise motor parameters directly determine the accurate of the magneticfield orientation, so as to influence the speed estimate and the performance of the system. Thisdissertation analyzes the influence of the motor parameters on speed sensorless vector control system.And the parameters off-line identification is studied.In this dissetation, three-level inverter space vector modulation, selective harmonic eliminationmodulation and hybrid modulation are simulated by Matlab software. The speed sensorless vectorcontrol based on full-order flux observer is also simulated. On this basis, DSP programming is carriedon a3kw induction motor. The experiment platform is based on TI’s TMS320F28335.