Study On The SVPWM Vector Control System For Asynchronous Motor

In recent years, with the development of power electronics, micro-processor of motor control and the new theory of motor control, the control technology of asynchronous motor is highly promoted. Asynchronous motor has simple structure, low cost, comparable to DC motor control performance when using the vector control technology. Moreover, vector control of asynchronous motor has higher precision, wider peed-regulating range and faster response. After in-depth study on the principle of asynchronous motor vector control system based on Space Vector Pulse Width Modulation (SVPWM), an asynchronous motor vector control system based on the DSP control chip of TMS320F2812 is designed. Through simulation and experimental test, the performance of control system has been tested and evaluated.First, on the base of the low-voltage squirrel-cage asynchronous motor, the mathematical model under three-phase static coordinate system, two-phase static coordinate system and circular coordinate system are analyzed by using the theory of coordinate transformation. Then the components between torque and magnetic field of stator winding current are decoupled which uses the rotor-field-oriented technology. After space vector PWM modulation algorithms and implementation methods have been analyzed, dual closed-loop vector control system of asynchronous motor is worked out.Then, a mathematical model of asynchronous motor in staticα-βcoordinate had been established by the Matlab/Simulink, on this basis, a simulation model of asynchronous motor vector control system based on Space Vector Pulse Width Modulation had been established. The system include a motor module, coordinate transformation module, flux observer module, PI regulator module, SVPWM module and so on. Then some situations such as starting performance and input load for step, ramp and sine wave had been simulated and analyzed. The simulation results prove the above model's dynamic process accords with practical speed regulating process.According as the principle of vector control system for asynchronous motor, the hardware and software of the digital asynchronous motor vector control system based on the control chip of TMS320F2812 are designed. Hardware system include the circuit design and parameter selection of main circuit (rectifier circuit, filter circuit and inverter circuit), detection circuit(current, voltage detection circuit and the speed detection circuit) and auxiliary circuit; The software design includes main program, subprogram for interval timer, ADC sampling program, speed sampling program, PI adjustment program, rotor flux calculation program, etc. The method that SVPWM algorithm program on DSP is presented in detail. This program use fixed-point operation format and is compiled by the software development platform CCS3.3. Finally, comparing with the simulation waveforms, the test waveforms confirm that the design of vector system is effectual and feasible. The results and problems are discussed and analyzed. All of these lay the necessary foundation for the development of follow-up study and high performance motor control system.