Control method and parametric robustness analysis of PMSM driving spiral power spring based on incremental backstepping control

Permanent magnet synchronous motor (PMSM) with simple structure and high ratio of torque to inertia is used as the energy conversion device to tighten or release spiral power spring (SPS) in spiral spring energy storage (SSES) system. For simultaneous variations of torque and inertia of SPS and nonlinear characteristics of multivariable and strong coupling of PMSM in the operation of SSES system, current incremental backstepping controller is devised through Taylor series expansion based on the built mathematical model of SSES system and designed speed backstepping controller. The stability of the control approach and the robustness of implicit and explicit model parameters are investigated, and the control gains in incremental backstepping control (IBC) are determined. Theoretical analysis indicates that implicit model parameters uncertainty has no effect on the control performance in any case, and explicit model parameters uncertainty hardly affects system performance under IBC with appropriate control gains. The simulation and experimental results show that PMSM in IBC can track the references more accurately and quickly, compared with other three control algorithms. The dynamic tracking performance of speed and current are improved even in an abrupt change of the reference speed, which proves that the proposed control method has strong stability and robustness.