Direct Torque Control Improvements

**Chapter 4**

**Abstract**

methodology.

**1. Introduction**

[1, 2].

**67**

response is faster.

sizing equation, finite element analysis (FEA)

*Yuting Gao and Yang Liu*

Flux Reversal Machine Design

Flux reversal permanent magnet machines (FRPMMs) have a simple reluctance rotor and a stator with armature windings and permanent magnets (PMs). Due to the high torque density and high efficiency of FRPMMs, they have been widely used in many applications such as electric vehicle, wind power generation, etc. However, the general design method of FRPMMs has not been established in books. Therefore, this chapter will focus on introducing an analytical design method, which allows for fast design of FRPMMs. First of all, the analytical sizing equations are deduced based on a magneto motive force (MMF)-permeance model. After that, the effects of some key performances including average torque, pulsating torque, power factor, and PM demagnetization are analyzed. Moreover, the feasible slot-pole combinations are summarized and the corresponding winding type of each combination is recommended in order to maximize the output torque. Besides, the detailed geometric design of stator and rotor are presented. Finally, a case study is presented to help readers better understand the introduced design

**Keywords:** design method, flux reversal permanent magnet machine (FRPMM),

The topology of FRPMM is depicted in **Figure 1**. As can be seen, it has a slotted rotor without any windings or PMs, and a stator with armature windings and PMs mounted on each stator teeth. First of all, the structural characteristics of FRPMMs

1.FRPMMs are excited by PMs instead of the excitation windings, which are different with asynchronous motors and brushed DC motors. So, for FRPMMs, the rotor will not have copper losses, and the efficiency is relatively higher

2.The rotor of FRPMMs has no windings or permanent magnets, thus is suitable for high-speed operation and high-temperature operating conditions [3]. Moreover, the no excitation winding will keep away from the problems of friction noise and electric spark. So, FRPMMs are more reliable and require less maintenance [4, 5]. In addition, the rotor of FRPMMs is light in weight and has a small rotational inertia [6]; hence, the acceleration and deceleration

and the corresponding performance advantages need to be explained:
