Comprehensive Control of a Hybrid-magnet Variable-flux Memory Machine for Washing Machine Applications

Variable-flux memory machine is a novel permanent magnet machine, whose back electro-motive force can be manipulated using online magnetization current. The variable-flux principle contributes to wide-speed high-efficiency operation, especially the flux-weakening loss is reduced at high speed. This paper will propose a comprehensive control system for a hybrid-magnet variable-flux memory machine in the washing machine application. This application exhibits huge difference between the rated speed of 500 rpm and the maximum speed of 14,000 rpm. The proposed control system features a three-mode control with specific control approaches, i.e., maximum-torque-per-ampere control and flux-weakening control in a single magnetization state, efficiency-based magnetization state switch control, and feedforward-based magnetization current control between different magnetization states. Verified by experiments, the proposed control system provides the comprehensive control solution for the variable flux memory machine in the operation cycles.