Vector Control Of Electronic Pole-Changing For Induction Motor

In electric vehicles and electric traction applications, expecting that drive system not only provides high torque at low speeds to increase climbing ability, but also has the ability to drive vehicle to run high speed. Conventional machines are difficult to directly meet their requirements, generally use mechanical transmission system and field weakening control of motor to extend speed and torque range, but these are bound to increase vehicle weight and reduce efficiency. Based on the issue of expanding the range of speed and torque, pole-phase modulation induction motor is regarded as the target, open-loop constant V/f control and vector control are studied. The simulation and experiment results verify that the proposed control methods are feasible and effective.Firstly, the thesis analyses the structure of pole-phase modulation induction motor, uses the winding function to calculate inductance parameters and S-Function to construct the mathematical model of pole-phase modulation induction motor, then carry out the simulation verification. Comparing with the calculation results of the finite element software JMAG-studio, verifies the correctness of the mathematical model.Secondly, the thesis uses switching function to analyse and construct the mathe-matical model of a nine phase voltage source inverter, and uses the sampling method with asymmetrical rules to generate eighteen PWM signals to control the inverter. Based on these preconditions, the open-loop constant V/f control and vector control of pole-phase modulation induction motor are studied and verified. In the open-loop constant V/f control, by changing the value of pole-changing, the motor is able to work in 3 phase 12 poles,9 phase 4 poles or the transition of pole-changing that the range of speed and torque is extended. In vector control, by controlling the torque distribution function and space vector decoupling components to realize the function, and dynamic and static performaces of motor are better.Finally, the hardware and software of the system are designed, and the experiment of open-loop constant V/f control and vector control of pole-phase modulation induction motor is operated on this experimental platform. By comparing experiment results with simulation results, verifies the validity of using open-loop constant V/f control and vector control to extend the range of speed and torque.