Double-sided air gap control of module-based permanent magnet synchronous machine for low-speed and high-torque applications

This paper presents an air gap control algorithm of PMSM with double-sided air gap structure for low-speed and high-torque applications. In particular, the used machine consists of symmetrical configurations, module-based assembly, and double-sided air gap unlike the conventional three-phase machines. In addition, this type of machine has some ways for connecting the each stator winding, which is wye or delta connections. In this paper, each stator winding is connected by using Y-connection. Therefore, a conventional 3-phase inverter can be applied to operate the module-based PMSM. In order to perform the air gap control of the machine, the air-gap information between each stator and rotor is necessary to generate the normal forces. In this paper, the air gap control method is presented by controlling the air-gap. The each air-gap is continuously adjusted by the d-axis current control. The effectiveness of the proposed algorithm is verified through the several experimental results.