This article presents the general requirement of traction motor drives. The differences between traction motors and industrial motors are compared. The classification of traction motors is given and the characteristics of each type of motors namely DC motor, induction motor, permanent magnet (PM) motor, PM hybrid motor and switched reluctance motor are discussed and evaluated. The newly developed stator-PM machines are also introduced. The design consideration of traction motors is described with emphasis on sizing equation, selection of electric and magnetic loadings, speed ratings and etc. Moreover, system level consideration in traction motor design, including single or multi-motor configurations, fixed- or variable-gearing transmissions, geared or gearless, voltage level and etc., are also presented. Power devices and power converters for traction motor drives are discussed and evaluated. Control strategies for traction motor drives, including field-oriented control (FOC), direct torque control (DTC), artificial intelligent control (AIC), and position-sensorless control (PSLC), are presented and compared.

：定子永磁型无刷电机是一类永磁体和电枢绕组均位于 定子的新型永磁无刷电机，可方便地对永磁体和电枢绕直接冷却以控制其温度，并易于通过“永磁+电励磁”实现对电机气隙磁场的直接控制，从而获得无刷电机的宽范围调速；凸极转子既无永磁体也无绕组，结构简单可靠，适合高速运行；该电机兼具功率密度高、效率高、容错性能好、控制灵 活等特点。该文介绍了定子永磁型无刷电机的基本结构与工作原理，总结了它们的共性规律和个性差别，对其分析设计方法、控制策略等关键技术进行综述，讨论了多种磁通调节 方案和容错控制策略，分析了该电机系统在电动汽车、飞轮储能、轨道交通等领域应用的可行性和潜力，最后对该电机系统的主要研究方向进行了展望。

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.

In this paper, a nonlinear varying-network magnetic circuit (VNMC) modeling method is developed for doubly salient permanent-magnet (DSPM) motors. The method is used to analyze the static characteristics of DSPM motors by specific permeance calculations, in which the interaction between the permanent-magnet field and the armature current field, as well as magnetic saturation, are taken into account. Two newly proposed DSPM motors (12/8-pole and 6/4-pole) are used as examples. There is good agreement between the results of the nonlinear VNMC modeling method and finite-element analysis. Moreover, the nonlinear VNMC method offers the advantage of calculating, effectively and efficiently, the static characteristics of DSPM motors having different dimensions, parameters, and conditions. Finally, the proposed method is verified by experimental testing of a 6/4-pole prototype.

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.