A Study on the Design Method for Improving the Efficiency of Spoke-Type PMSM

Considerable progress has been achieved in motor design and control and related material technologies. Motor driving systems are increasingly being incorporated in various applications, such as transportation machines, including hybrid/electric vehicles, and industrial machines, including robot, crane, rolling mill machine, and home appliances. However, various motors used in such applications consume the majority of electric energy generation. Increasing electric energy generation through the expansion of a power generation system is time-consuming and requires considerable money and time. Therefore, a high-efficiency motor should be designed. Domestic and foreign standard agencies are implementing policies and standards to grade energy efficiency based on the electric energy used by motors. A study was conducted on improving motor efficiency for home appliances. When designing a high-efficiency motor for home appliances, a design plan that maximizes the magnetic flux density of the air gap and reduces various losses was first considered. In this study, a spoke-type structure was proposed to maximize the effective magnetic flux density in the air gap for achieving high-efficiency motors. The space available for fitting motors inside applications is reducing. For miniaturization and improving the efficiency of the motor considering space constraints, the application of the overhang (O/H) and spoke-type structures was considered. In addition to the O/H structure, electrical steel sheet SRA was investigated for reducing iron loss. The effect of the spoke-type structure with O/H applied for high efficiency was verified through 3-D finite element analysis and experimental results after motor manufacturing.