Online Loss Minimization Control of IPMSM for Electric Scooters

An electrical losses (copper and iron losses) minimization control of interior permanent magnet synchronous motors is proposed in this paper. Until now a Look-up Table based maximum torque per armature current control strategy was proposed by authors. That is a control to minimize copper losses. Meanwhile, the efficiency deteriorates as a result that the iron losses increase sharply in high speed area. In this paper, a model considering iron losses is discussed and the relationship between the electrical losses and d-q axes current, motor torque, motor speed is clarified at first. Next, measurement experiments are made to prove that there is an optimal armature current phase which minimize the electrical losses for given motor speed and load torque. Then, an online loss minimization algorithm with steepest descent method (golden section method) is proposed. The electrical losses in i_d = 0 control and loss minimization control are compared with experiment results. The effectiveness of the proposed control is verified by experiments.