The SMMA (Small Motor & Motion Association) held its annual fall Technical Conference in St. Louis this past week. Every fall the conference brings together engineers and motor designers to share and learn about the latest in motor design techniques and the motor and motion control industry in general.
This year’s theme was Motors, Materials, and Manufacturing. With over two dozen individual sessions over three days, the topics ranged from the fundamentals of brushless DC motor design and the fundamentals of materials used in electric motors (including magnets and bearing grease) to specific industrial applications of motors.
Even with this broad range of coverage, one theme continued to pop up throughout; interest in permanent magnet (PM) motors.
PM motors aren’t a new technology. They’re known for being highly efficient and producing high torque. The one drawback to date has been their relatively higher cost than other types of motors. However, with PM motor costs decreasing, the motors are becoming more viable options in many applications where in the past their use was cost prohibitive.
As a result, there is growing interest in optimizing PM motor design and performance, and conference presentations reflected that. For instance, a paper presented by Chandan Sikder, a PhD student from North Carolina State University, proposed a method to reduce cogging torque in PM machines using a method of rotor pole shaping. Another presentation from Emmanuel Agamloh of Advanced Energy focused on PM motor use in industrial applications, including the efforts to establish uniform design and testing standards for PM motors through an IEEE standard.
One of the applications where PM motors are being used is in hybrid electric vehicles (HEVs). (This Design World article compares the performance of an induction motor and a PM AC motor.) In these applications, size and weight tend to be important design factors in addition to motor performance. However, in the industrial applications, a clear driving factor is the focus on improving energy efficiency on manufacturing floors. And PM motors, with their high efficiencies and high torque, are looking increasingly attractive.