PWM carrier harmonic iron loss reduction technique of permanent magnet motors for electric vehicles

This paper is investigated to increase fuel economy of motor for electric vehicles (EVs) traction system. Low torque region of EV motor is frequently-used point in usual urban driving and in fuel economy measurement. Pulse-width modulation (PWM) carrier harmonic iron loss takes up high percentage for EV motors in this region. This paper reveals the relationship between phase current and carrier harmonic iron loss for permanent magnet synchronous motor (PMSM) in low torque region. Then, a novel carrier harmonic loss reduction technique is proposed, which is applied two set of three phase windings for concentrated winding PMSM. The loss reduction effect is tested successfully on a 70 kW EV motor as well as two dimensional finite element method (2D-FEM) calculation. The efficiency of developed motor is calculated and compared with that of conventional motor in JC08 mode driving cycle.