| Abstract |
Interior Permanent Magnet (IPM) Motors have become a popular choice in electric vehicle applications, due to their excellent power to weight ratio. The paper describes the implementation of the field-weakening strategy that allows a 4:1 speed ration in a 50 kW (peak power) motor, with a base speed of 2500 rpm. The attractive features of the controller are highlighted in both low and high speeds of operation, where losses are minimised and peak power is made available up to 10.000 rpm. At low speeds, the reluctance torque is used to maximise the output for a given current level; this is achieved in the practical implementation selecting an optimal value of the direct stator current component. On the other hand, at higher speeds the system reaches a point at which the converter will not be able to supply the desired voltage. In this case it is necessary to make use of an increased value of the direct current component. The results presented here are for both simulation and practical implementation using a voltage source inverter supplied from a traction battery with a nominal 300 V. A discussion on further improvements and dynamic characteristics of the system is finally presented to conclude the paper. Hardware and software development have been carried out under the Project Supervision of ABB Hybrid Systems based in Vasteras, Sweden. |
