Abstract: Permanent magnet brushless motor (PMBM) has been one of the main traction motors used in electric vehicle (EV). A vector control method with low cost and high performance is presented to meet the requirement of EV, such as high torque at low speed, wide adjustable speed range with constant output power at high speed. The method takes vector control of PMBM with discrete position signals at EV start and at low speed, and with continuous position signals at high speed. Without increasing the cost of PMBM and its control system, this method gets rid of the disadvantage of narrow field-weakening speed range for PMBM at high speed, and upgrades the performance of PMBM in the whole speed range

Key words: Discrete position signal, Permanent magnet brushless motor, Phase plane analysis, Vector control