Optimal Design Of Squirrel-Cage Permanent Magnet Brushless Motor

The Squirrel-Cage Permanent Magnet Brushless Motor(SC-PMBM)is similar to the traditional Asynchronous Motor in structure as they both have squirrel-cage on rotor.According to different control strategies,the SC-PMBM can be divided into Line-Start Permanent Magnet Synchronous Motor(LS-PMSM),Squirrel-Cage Permanent Magnet Brushless AC Motor(SC-BLAC)and Squirrel-Cage Permanent Magnet Brushless DC Motor(SC-BLDC).The SC-PMBM not only has the line-start ability same as the asynchronous motor but also has typical advantages such as higher efficiency and power factor over a wide load range.Besides,introducing rotor Squirrel-Cage in SC-BLDC may also increase the motor output power and decrease the eddy-current loss of its rotor.Hence,the SC-PMBM becomes more and more focused by researchers,its design technology has also been improving all along.In many industrial fields,the SC-PMBM has begun to be applied in order to replace the traditional asynchronous motor.However,due to the complexity of rotor structure and the immaturity of motor optimal ization,it has not been widely utilized yet.The thesis takes this as the breakthrough point to study the optimalization of the LS-PMSM and SC-BLDC separately.During the process of research,FEM simulation software such as Maxwell Ansoft and Magneforce are used to analyze the influences of cage bar parameters on the motor performance.The influences of PM motor’s rotor cage on the air-gap flux density,back EMF waveform,cogging torque and steady-state performance are analyzed.The influences of rotor cage’s material,slot type,bar number and bar distribution on the performance of LS-PMSM are analyzed.Also,a kind of optimization method called asymmetrical cage bar distribution is proposed,then al.1 kW LS-PMSM prototype with 4 magnetic poles was optimally designed and manufactured and the contrast experiment between the optimal prototype and the original motor has been done.The influences of rotor cage’s size,depth and distribution on the steady-state performance and rotor eddy-current loss of the SC-BLDC are also investigated.