Jianyi Zhang

This paper focuses on the tracking controller design for PMSM servo systems subject to both current constraints and voltage saturations. Toward this end, a novel system transformation technique is first proposed to transform the current-constrained PMSM servo system into an equivalent “unconstrained” one. In particular, to reduce the effects of the current over-constraint (i.e., the excessive constraint on the motor current) on the control performance, a safe boundary is introduced in the proposed system transformation scheme. In this way, the current constraint mechanisms are activated if and only if the current is close to its constraint boundaries. Then, by virtue of the transformed model and the backstepping design procedure, an extended state observer (ESO) based nonlinear control strategy is developed, where two ESOs are employed to compensate for system disturbances. In addition, an auxiliary system with saturation error serving as the input is established to address the effects of the voltage saturation. The theoretical analysis demonstrates that the proposed control strategy guarantees the desired performances under both the current constraint and voltage saturation. Finally, the hardware experiments are performed on a 5.5 kW PMSM to validate the effectiveness of the proposed method.

For the speed-tracking control of permanent magnet synchronous motor (PMSM) systems, fast dynamic response and high reference speed require a large transient current to provide sufficient electromagnetic torque. However, the excessive transient current may damage the drive circuit and threaten the system safety. Besides, it is also important to pay attention to the influence of multiple disturbances including system parameter uncertainties and unknown load torque variation. To solve these problems, we propose a nonlinear speed-tracking control approach for uncertain PMSM systems. More specifically, based on the cascade control structure and by introducing auxiliary smooth function, we first develop a nonlinear current-constrained controller (CCC) to guarantee the speed tracking, disturbance rejection, and overcurrent protection simultaneously. In order to improve the robustness of the desired performances, we further implement extended state observer (ESO) techniques to propose an ESO-based CCC (ESO-CCC). Finally, comparative experiments are implemented in a 5.5 kW PMSM platform to verify the performance of the proposed two controllers.

In this paper, we investigate the speed tracking control problem for permanent magnet synchronous motor (PMSM) drive systems. In particular, the current constraint, parametric uncertainties, and the external load disturbance are addressed simultaneously. To deal with these issues, we first propose a system transformation scheme, which equivalently transforms a PMSM system with the current constraint into the one without any constraints, thereby reducing the difficulties in the controller design caused by the current constraint. Based on the transformed system, the adaptive parameter estimation and robust control are integrated to derive a current-constrained adaptive robust controller (CCARC), which guarantees the robust tracking performance under the current constraint, parametric uncertainties and the external load disturbance. For the closed-loop system, the Lyapunov-based analysis is provided to show the convergence and stability. Finally, the effectiveness of the proposed method is experimentally validated using a 5.5 kW PMSM.