Design and analysis of low-speed high torque direct-driven permanent magnet synchronous machines(PMSM) with fractional-slot concentrated winding used in coal mine belt conveyor system

This paper studies the characteristics and design concept of low-speed high-torque direct-driven PMSM with fractional-slot concentrated winding used in coal mine belt conveyor system. The fractional slot concentrated winding PMSM with high efficiency, high power density and simple windings type is used widely, and more attention is paid to the influence of cogging torque with different slots and poles, but less attention is paid to the effect of the different between different stator conductor turns loss on open-slots motor and rotor magnet loss caused by harmonic field. In this paper, taking a 500kW 60RPM 1140 V low speed permanent magnet direct-driven motor as an example, it presents that the difference between different stator conductor turns loss of multi-polar few slot motor and the rotor magnet loss by the EFA simulation and temperature field calculation, which are not uniform and easily overlooked, will be leaded to serious temperature rise problems. A new rotor topology structure design and some measures on how to reduce stator copper loss and rotor eddy current loss are propose. The prototype machine was developed and tested to validate the feasibility and correctness of design and analysis.