Analysis and Performance Evaluation of an Efficient Power-Fed Permanent Magnet Adjustable Speed Drive

Abstract

This paper proposes a novel power-fed permanent magnet adjustable speed drive (PF-PMASD) to regulate the speeds of pumps and fans for energy saving. The drive features that the slip power induced in the wound rotor of the drive can be fed to the power grid by a power electronic converter. The structure, operation principle, and control strategy of the drive are introduced and investigated. The mathematical model of the PF-PMASD is built by referring to the models of the traditional permanent magnet synchronous machine and wound rotor induction motor, based on which the power-size equation for the drive is deduced. The losses and efficiencies of the drive under different slips are also calculated and evaluated. The relationships between the slip and the duty cycle of the insulated-gate bipolar transistor in the boost chopper are revealed by the mathematical model of the control unit. The steady characteristics including electromotive forces, phase currents, and torques under different operation states are computed and analyzed comprehensively by finite-element analysis. The speed regulation characteristics, the power factor, and the energy-saving capabilities of the drive are investigated by experimental test. The analysis results indicate that the proposed PF-PMASD possesses a remarkable speed regulation capability with high efficiency.