Constrained Predictive Controllers for High-performance Sensorless IPMSM Drive Systems with Full-range Speed Operations

A constrained predictive speed controller (CPSC) with an input current limit and a constrained predictive current controller (CPCC) with an input voltage limit are proposed for high-performance sensorless IPMSM drive systems. Recent predictive controllers for sensorless IPMSM drives tend to focus on unconstrained predictive controllers which do not consider the voltage or current limitations of inverters and may cause responses which are not smooth. The proposed constrained predictive controllers in this paper solve these problems by imposing constraints in the performance index for real-time optimization. Simplified numerical solutions which use Hildreth quadratic programming (HQP) are used to identify active constraints, and then the control inputs are limited within their physical ranges. In addition, a simple external load estimator based on the Lyapunov function is designed to compensate for external load disturbances. Moreover, a current-slope-based rotor position estimation method, which does not require any extra hardware or high-frequency signal generators or occupy any DC-link voltage, is implemented to accurately estimate the rotor position and speed. The proposed method in this paper improves the dynamic performance and reduces computational complexity when implemented in sensorless IPMSM drive systems. The proposed methods have quick transient responses, excellent load disturbance responses, good tracking capabilities, and good robustness. The sensorless IPMSM drive system proposed in this paper is operated at full-range speeds, from 1 r/min to 3,000 r/min. Several simulations and experimental results validate the effectiveness of the proposed constrained predictive controllers.