Speed and torque range increases of electric drives through compensation of flux weakening

摘要

Electric drives for automobiles require at low speed for starting a torque which is a multiple of the rated torque, and for above rated speed a torque which is about the rated torque. Known (V/f) control results in a decreasing torque above rated operation while the (V · p)/(f · N) control -where the terminal voltage V=3DVt is less or equal to Vrated, the number of series turns of the stator winding N is less or equal to Nrated - increases torque, speed operation, and power rating. This new control is accomplished by employing pole-changing techniques and/or changing/switching the number of series turns per phase N of an alternating current/voltage machine combined with the use of an inverter/rectifier supplying/absorbing power to/from the machine when operated as a motor/generator. The switching techniques have about the same effect as a mechanical gear.