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

Interior Permanent Magnet (IPM) drives are particularly adapted to flux-weakening, then to constant power operation over a wide speed range. Most of the Space-Vector strategies for IPM are based on current vector control. Flux-weakening is obtained by setting the current reference according to the magnetic model of the motor. If the dc-link is not constant, an additional voltage loop is needed. By controlling the flux vector instead of the current vector, in the stator-field-oriented frame, the motor voltage is easily dominated. A control algorithm, based on stator field-orientation, is proposed and tested on an IPM drive designed for light EV traction. The full exploitation of the motor torque is obtained over a wide speed range at given inverter kVA. The case of spread on the dc-link voltage is also analyzed. Well matched discrete-time simulation and experimental results are reported.