This paper gives a comprehensive review of the state of the art of wind energy conversion systems (WECS) and technologies, with an emphasis on wind power generator and control. First, different types of common WECSs are classified according to their features and drive train types. The WECSs are compared on the basis of the volume, weight, cost, efficiency, system reliability and fault ride through capability. The maximum power point tracking (MPPT) control, which aims to make the generator speed meet an optimum value to ensure the maximum energy yield, plays a key role in the variable speed WECSs. A comprehensive review and comparison of the four most popular MPPT control methods are carried out and improvements for each method are presented. Furthermore, the latest development of wind energy conversion technologies is introduced, such as the brushless doubly fed induction generator (BDFIG), the stator permanent magnet synchronous generators, the magnetic-geared generators, dual power flow WECS with the electrical variable transmission (EVT) machine, and direct grid-connected WECS. Finally, the future trends of the technologies are discussed.

Permanent magnet (PM) brushless machines having magnets and windings in stator (the so-called stator-PM machines)have attracted more and more attention in the past decade due to its definite advantages of robust structure, high power density, high efficiency, etc. In this paper, an overview of the stator-PM machine is presented, with particular emphasis on concepts, operation principles, machine topologies, electromagnetic performance, and control strategies. Both brushless ac and dc operation modes are described. The key features of the machines, including themerits and drawbacks of the machines, are summarized.Moreover, the latest development of the machines is also discussed.

磁通切换永磁电机具有功率密度高、输出转矩大、反电动势正弦等优点，而较高的气隙磁密与定转子双凸极结构会产生较大的定位力矩。定位力矩会引起电机运行时的转矩脉动、振动和噪声问题，从而限制了磁通切换永磁电机的应用。从控制角度出发，提出一种新型的采用电流谐波注入法补偿定位力矩的控制策略，即通过注入谐波电流产生的转矩抵消定位力矩中的基波与二次谐波分量，从而达到补偿的目的。通过半实物仿真平台dSPACE实现了该控制算法，并在一台2kW磁通切换永磁电机的驱动系统上验证了所提出补偿控制方法的有效性。该控制方法也可拓展应用到其它反电动势为正弦且定位力矩较大的永磁电机驱动系统。