Improved Rotor Position and Speed Estimators for Sensorless Control of Interior Permanent-Magnet Synchronous Machines

Model-based rotor position/speed estimators are commonly used for sensorless control of interior permanent-magnet synchronous machines (IPMSMs) operating in the medium- and high-speed regions. A rotor position/speed estimation scheme usually contains three major parts: 1) a state observer; 2) a position estimator; and 3) a speed estimator. This paper proposes a sliding-mode observer (SMO) as the state observer to estimate the position-related system states, which are the extended electromotive force components in this paper. Then, two major contributions are made to achieve improved position and speed estimation. First, the rotor speed is estimated independently using a model reference adaptive system (MRAS)-based method, which is decoupled from the position estimation. To reduce the noise contents in the estimated speed, an adaptive line enhancer is proposed to work with the SMO, leading to an improved reference model for the speed estimation. The proposed MRAS-based speed estimator has two operating modes, which are suitable for generator and motor applications, respectively. Second, the estimated rotor speed is used as a feedback input signal to mitigate the oscillating error in the estimated rotor position, leading to an integrated position and speed estimation system. The effectiveness of the proposed position and speed estimators is verified by simulation using the data logged from a real-world test vehicle. Experimental results on a test stand of an IPMSM drive system used in off-road, heavy-duty hybrid electric vehicles are also provided to further validate the proposed rotor position/speed estimation schemes.