Galvanically Isolated On-Board Charger Fully Integrated With 6-Phase Traction Motor Drives

Abstract

The rapid spread of electric vehicles is pushing for more and more compact and reliable e-axle architectures. In this scenario, the integration of the on-board battery charger with the traction drive can be a feasible way to reduce the embedded volume and number of components. Anyway, integrated chargers often present safety issues due to the absence of an isolation stage. In this work, a solution is proposed for integrating the on-board battery charger with the traction drive of road electric vehicles equipped with a 6-phase traction motor drive. The proposed charger is deeply integrated within the e-drive powertrain, to reduce the cost and volume of the e-axle with respect to non-integrated solutions, but still providing galvanic insulation, differently from all fully integrated charger in the literature. Dedicated control strategies are developed and tested for regulating the AC grid current at unitary power factor and low THD, and to avoid torque production or rotor movement during charging independently from the rotor position. Extensive simulation results show the feasibility of the proposed solution, together with a proof-of-concept validation on a commercial traction motor.

Keywords

• On board charger
• multiphase synchronous motor
• electric vehicle
• integrated OBC
• PFC
• multiphase machine