Magnet flux optimization method for Line-Start Permanent Magnet motors

Abstract

The use of induction motors is the right choice for a great number of household appliances which look for cost-competitive solutions. Therefore, in the past few years, the energy consumption became also an important issue which drives the design of electrical motors, although, permanent magnet motors came to stay. Most of the solutions which are significantly efficient to worth using have also a high cost due to electronics, and among the few options that can be used on this kind of application is the Line-Start Permanent Magnet (LSPM) motor. This paper shows a simple design procedure to increase the net flux generated by the magnets maximizing the magnet short-circuit reluctance and reducing the flux loss in the rotor slot bridges. This method can be used to reduce the magnet volume, also reducing the total cost of the motor, which can contribute to make the LSPM motor a real option to substitute the induction motors in the future. The LSPM motor is analyzed using a 2D finite element method and the rotor movement is modeled by means of the moving band. This approach allows to investigate the influence of design variations on the dynamic behaviour of the LSPM motor.