Development of a High Power Density Motor Made of Amorphous Alloy Cores

In this paper, the development of a permanent-magnet (PM) motor made of amorphous alloy (AA) core is presented. The motor is rated as 20 kW, and base speed is 2500 r/min. A massive produced interior PM motor used in electric vehicle traction application is chosen as the baseline motor. An optimization software package built based on Matlab platform is used to design the stator made of AA, while the rotor is preliminary designed with the help of analytical formulation aiming at lowest core loss in stator teeth and finally tuned by finite-element analysis. The optimized AA motor is 31% smaller in volume than the baseline motor while keeping the continuous power rating unchanged, which means 45% more in power density. To validate the mathematical model beneath the optimization software package, two prototype motors have been manufactured. The first motor is the AA motor, optimized in this paper, and the second motor has exactly the same lamination shape and structural design of motor 1 but its material is nonoriented silicon steel like the baseline motor, instead of AA. The test result show the efficiency of motor 1 is higher than the baseline motor in full speed range, and motor 2 is badly behaved in terms of efficiency. The observation from the test proves that simply replacing the silicon steel with AA does not work under all circumstances, and the optimization experience gained for the AA cannot be used directly in designing a silicon steel motor.