Twelve-phase open-winding SPMSM development for speed dependent reconfigurable traction drive

Commercially available electrical machines are generally not optimized for a broad operating range, as required in e.g. vehicle traction applications. The required mechanical angular velocity of the wheels for electrical vehicle propulsion is relatively low (around 1,000 rpm), while the torque demand is high (around 500 Nm). This combination requires an adequate solution in the mechanical, electromechanical or electrical domain. No cheap, reliable, lightweight and efficient solution has been invented yet. This paper presents an operation method for a dynamic electric vehicle propulsion system using variable torque/speed characteristics. With this method, the speed range of an electrical machine can be extended. The twelve-phase open-winding surface permanent magnet synchronous machine presented in this paper is developed to verify the different dynamic drive operation modes in practice.