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The efficiency of the motor driving system in the electric vehicle affects the utilization factor of the power source and the driving range of the EV. The loss of the PMSM drive system is tested with the low speed. The modulation of carrier frequency in PMSM was discussed in this paper. According to the working situation of the EV, the carrier frequency would change to improve the effective of the driving system. The result of the simulation and the experiment show that the effective of the PMSM can be improve about 3.5%.

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This paper builds a numerical model of calculating the contact thermal resistance between IGBT and cooling substrate in drive-motor controller. And it analyses the influence degree of four factors on contact thermal resistance based on the model: the substrate material, the pressure, the surface roughness and the filling radiating material. As the core element in drive-motor controller, the heat radiation of IGBT is the most important problem, and the contact thermal resistance is a large part of thermal resistance. In order to reduce the resistance, which factor influences it largest must be known. A simulation is made to compare the influence of each factor based on MATLAB, which shows the factors should be thought by turns: the filling radiating material, he surface roughness, the pressure then the substrate material.

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In this paper, a new way of voltage transform is designed. It directly transforms the voltage of the PWM (Pulse Width Modulation) waves whose fundamental wave is sine wave. As the fundamental wave is sine wave with 50Hz, it uses the common cold-rolled silicon steel as transformer core, which significantly reduces the cost of the voltage conversion device and improves the reliability of the voltage conversion device.