Mechanical sensorless speed control of PMSMs using an instantaneous complex power formulation

Abstract

In this paper two mechanical sensorless strategies to control the rotor speed in permanent magnet synchronous motors (PMSMs) are introduced and compared. Both strategies are based on the same full feedback linearization nonlinear control strategy for the motor model formulated by using the instantaneous complex power theory. However, this strategy is transformed into mechanical sensorless in a different way. In a first case, a nonlinear reduced order observer is designed for estimating rotor position and speed, whereas in the other case a full order observer is used to obtain the rotor position and speed estimates. In a first approach, it is assumed that the load power is a known function of the mechanical variables. In the second approach, the load is assumed unknown and both observers are extended to calculate a load power estimate. In this way, two different extended observers result. The performance of both mechanical sensorless strategies are compared via simulation results.