Improvement of flux-weakening control of surface mounted permanent magnet synchronous machine considering inverter nonlinearity

This paper proposes the flux-weakening control of the surface mounted permanent magnet synchronous machine in which the voltage losses, for example, inverter nonlinearity and winding resistance voltage drop are considered. In the constant-torque region, to achieve the maximum torque, the d-axis and q-axis currents are controlled tracking the maximum torque per ampere (MTPA) trajectory, while those currents are modified in the flux-weakening region. The proposed method exhibits a good weakening current response because the requirement of d-axis current can be significantly reduced in the infinite constant power speed range compared to the conventional method, which voltage losses are not considered. Accordingly, the efficiency and power factor in the flux-weakening region can be improved. The effectiveness of the proposed method is proved by simulation results.