Research And Realization Of BDFM Control System Using Three-level Inverter

With the increasing consumption of energy resource in our country, high voltage and high power inverter system has been spreaded as an important way of energy-saving and emission-reduction. Three-level inverter control system of BDFM had been extensivly focused due to high voltage, fine reliability, high efficiency and few current harmonic wave. It becomes a hot topic in the study of high voltage and high power inverter system.The research was based on three-level neutral point clamped inverter, considering the requirement of high power AC speed governing system. This study was based on the control tactics of three-level neutral point clamped inverter of BDFM as well as brought out two improvments and experimental research. The main work are as follows:The DTC method this research studied was based on SVPWM, and it had a lot of trigonometric functions, in order to solve the problems of complicated calculation and large ripples of flux and torque, a SVPWM method based on 60° coordinate was proposed. Voltage vectors in other sections were transformed to the first section, this method reduced the amount of calculation and improved the flexibility and availability of system.This research studied the DTC method basing on fixed synthesizing vectors. In order to solve the problems of imbalanced neutral point voltage and unstable flux and torque, a fixed synthesizing vectors method based on hysteresis control of neutral point voltage was proposed. Space voltage vectors synthetize fixed synthesizing vectors according to a certain way. Every fixed synthesizing vector expressed the changing of flux and torque. Collecting capacity’s voltage, and distributing time of small vector in order to reduce the neutral voltage.In order to prove the practicability and availability, this paper proposed two improvements and made simulations under MATLAB/SIMULINK.Lastly, it built the hardware platform of three-level inverter control system of BDFM.The hardware system includes driving circuit, controlling circuit, detecting circuit, protecting circuit and so on. Software exploit was under CCS3.3. By experimenting and testing, it proved the feasibility of the whole system.