Field-weakening is an established technique for exceeding motor base speeds while maintaining constant input power. To improve energy efficiency of emergency ventilators, this paper presents a methodology for reducing torque to lower the input power of brushless DC (BLDC) motors during phases of constant pressure. Using the Clarke-Park transformation, the operating point is obtained by minimizing the voltage and then applied as phase-advance angle and modulation index in the voltage model. A proof-of-concept experimental setup yields power savings of up to 40% using field-weakening compared to conventional field-oriented control approaches, demonstrating its feasibility for energy savings in BLDC motors.
Schild et al. (Thu,) studied this question.