Research on Cooling Problem of a Modular Permanent Magnet Synchronous Machine Based on a 3D Equivalent Thermal Network Method

Due to the huge volume of gearless ball mill direct drive permanent magnet synchronous machine (PMSM), an unwinding modular technology is convenient for its redundant power control, manufacture and maintenance. Several module units are wrapped around the ball mill roller for direct drive. The motor frame adopts a modular structure to achieve complete decoupling between modules. And the cooling problem of the motor is very important for its stable operation. The traditional waterway structure design and cooling analysis methods are difficult to meet the engineering requirements of large modular permanent magnet synchronous machine (MPMSM). A 3D equivalent thermal network method is proposed to study the cooling problem of MPMSM. The design program of modular frame cooling structure is written based on a 3D equivalent thermal network method. According to the temperature distribution of each node, the cyclic check is carried out to quickly design the modular waterway. The cooling effect of the designed waterway structure is analyzed by fluid-solid coupled temperature field simulation. An 80 kW prototype is developed and the temperature rise experiment is carried out. The simulation and experiment results prove the rationality of a 3D equivalent thermal network method for the MPMSM cooling structure design.