Salient PM Rotor Topology Selection for a Zero-Speed Injection Based Sensorless Controlled Machine

In this paper a performance comparison of permanent magnet (PM) salient rotor topologies is conducted. The analysis has been carried out for a machine design case study where numerous design requirements need to be satisfied simultaneously. The requirements include: low speed, high torque, low-duty transient operation and zero-speed injection based sensorless control capability. The majority of work in this field treats the problem of PM machine design for sensorless control in a decoupled manner, where only the rotor or stator geometry is altered to achieve the required sensorless performance. Such an approach makes the performance comparison between various machine topologies challenging, as they are usually designed using different techniques, or initial design assumptions. In this paper a holistic design approach is used where the stator and rotor sub-assemblies are optimised together. This allows an unbiased comparison between the candidate machine designs. The following six salient rotor topologies have been considered: inset, spoke, flat-IPM, V-IPM, dual layer V-IPM and inset with cut-out. The most promising design variants have been selected and are discussed in detail, with the aim to select the best performing machine design for prototype manufacture.