Optimal exploitation of the Constant Power Region of IPM Drives Based on Field Oriented Control

Interior Permanent Magnet (IPM) drives are particularlyadapted to flux-weakening, then to constant power operationover a wide speed range. Most of the Space-Vector strategiesfor IPM are based on current vector control. Flux-weakeningis obtained by setting the current reference according to themagnetic model of the motor. If the dc-link is not constant,an additional voltage loop is needed. By controlling the fluxvector instead of the current vector, in the stator-field-orientedframe, the motor voltage is easily dominated. A controlalgorithm, based on stator field-orientation, is proposed andtested on an IPM drive designed for light EV traction. Thefull exploitation of the motor torque is obtained over a widespeed range at given inverter kVA. The case of spread on thedc-link voltage is also analyzed. Well matched discrete-timesimulation and experimental results are reported.