There are two classic strategy for AC motor control, they are vector control and direct torque control. In this paper, a new closed-loop control method based on vector control is proposed. We first introduce the basic formula of the J-M transform strategy. Secondly, the control block diagram of closed loop control based on J-M transform is analyzed in detail. Finally, the results of simulation are carried out. The simulation results show that the method of closed loop control based on J-M transform strategy can control AC motor effectively.

Due to the small volume and high-power density of new energy vehicle motor, a large number of losses in the working process are converted into heat accumulation, resulting in temperature rise, which affects its efficient operation. Based on the heat conduction mechanism, four kinds of shaft oil cooling models with different structures are designed, which are comprehensively analysed by using the thermal-fluid-structure coupling analysis method, and the most effective cooling shaft oil cooling model is solved. The simulation is based on Ansoft Maxwell, and the loss results of each component of the motor are obtained, and the loss data is imported into the Fluent software for fluid-structure coupling analysis. By keeping the other variables consistent, the oil flow rate, pressure drop, and temperature rise of four kinds of in shaft oil cooling structures are analysed and compared. The experimental results show that the rectangle around type is the optimal oil cooling structure. In addition, based on the rectangle around oil duct model , the thermal-fluid-structure coupling analysis of the whole motor is carried out, and compared with the motor without cooling system. The temperature rise cloud diagram of the two motors shows that the former has more obvious heat dissipation effect than the latter, and effectively reduces the temperature rise of the motor, especially the rotor and permanent magnet parts, which verifies the rationality of the shaft cooling structure design.

Induction machines are very competitive in price and maintainability when compared to PM machines and DC machines. Therefore, many induction machines are used for electric vehicles and hybrid vehicles. While it is relatively easy to control an induction machine at high speeds, it is difficult to control the speed and torque of an induction machine at low speeds. With field-oriented control, an induction machine can perform somewhat like a DC machine. This paper demonstrates the theory and implementation of field-oriented control of an induction machine. A mathematical model was developed. Special considerations were given to the flux observer and the implementation of PI controller. A control system was implemented on a 650W prototype induction motor to confirm the proposed method.