Novel Voltage Limiter for Fast Torque Response of IPMSM in Voltage Saturation Region

Abstract

A new voltage limiter for fast torque response of IPMSM in voltage saturation region is proposed, which we name “maximum torque response voltage limiter”. In transient condition, the fastest response is vital while voltage saturation occurs. Then the problem is that how to divide the limitted voltage to d and q axis voltages for generating the fastest torque response. The nonlinear relation between torque and d-q axis currents of IPMSM makes the problem complicated.In our proposed method, both voltage equations and a torque equation of IPMSM are considered and, based on Lagrange optimization technique, the explicit expression of d and q axis voltages are derived. Compared with the conventional voltage limiter such as constant phase angle method, constant back emf. method and constant d-axis voltage method, the proposed limiter yields faster torque response in voltage saturation region, which is confirmed by computer simulation and experimental results. Furthermore, the proposed method uses simple software calculation, and it can be readily implemented without any modification of hardware system.