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The speed regulation technology for energy conservation of pump and fan systems occupies an important position in industrial field. The paper focuses on the rapid development and research significance of speed regulation technology for energy conservation based on different permanent magnet adjustable speed drives (PMASDs). The development history and speed regulation scheme for energy conservation are introduced step by step. The features of theoretical model based on magnetic vector potential and equivalent magnetic circuit methods are presented and studied in the paper, which is benefit to select a suitable method for a specific drive. Several optimization methods of design parameters of PMASDs are given in the paper. The structure and operating principle of some new speed regulation scheme are described, and their advantages, disadvantages and feasibility of engineering application are analyzed. Finally, the proposed speed regulation technologies for energy conservation are summarized and classified from the aspects of magnetic circuit structure, permanent magnet rotor structure, conductor rotor structure, and the slip power conversion scheme. In a conclusion, the power-fed PMASD will be the future of energy conservation technology for the high-efficiency and low-cost large pump and fan systems.

This paper proposes a novel flux adjustable permanent magnet eddy-current coupling with a movable stator ring (MSR). The slip speed of the proposed coupling can be adjusted by shifting the MSR along the axial direction. The structural feature and operation principle of the coupling are illustrated. An analytical model based on magnetic equivalent circuit method is built to compute its electromagnetic characteristics efficiently. The dynamic process of the MSR movement is simulated by employing a variable air-gap reluctance model. The eddy-current field under asymmetric magnetic field is calculated by an improved analytical method. The electromagnetic characteristics of the coupling, such as air-gap magnetic field, eddy-current, and torque-slip speed characteristics, are analytically investigated. The analytical results are verified with the results obtained by the 3-D finite-element method. [ABSTRACT FROM AUTHOR]