Performance Comparison of Six-Phase PM Machine with Several Winding Layouts for EV Applications

Abstract

This paper presents integrated on-board battery charging of electric vehicles (EVs) utilizing a six-phase drivetrain; namely, a six-phase permanent magnet (PM) machine equipped with fractional slot concentrated winding (FSCW) and a six-phase inverter. Integrated chargers outperform conventional on-board battery chargers (OBCs) since they exploit the propulsion elements in the charging process, which yields a reduction in the cost and weight of the EVs. Various FSCW slot/pole combinations have shown promise in EV applications, such as 12-slot/l0-pole and 18-slot/l6-pole. However, six-phase windings, i.e., dual threephase (D3P), symmetrical six-phase (S6P), and asymmetrical sixphase (A6P), are not viable for all slot/pole combinations. For example, the six-phase 18-slot/l6-pole machine can only be configured with a D3P winding configuration. Moreover, it is proven in the literature that the A6P is better than the D3P under the EV charging process from the radial forces’ perspective. Thus, this paper presents a comprehensive comparison of two six-phase integrated battery chargers using surface-mount permanent magnet (SPM) machines with D3P and pseudo six-phase (P6P) winding arrangements. The machine is first designed based on the magnetic equivalent circuit (MEC) model and optimized based on multi-objective genetic algorithm (MOGA). Finally, finite element (FE) simulations have been carried out to assess the two winding layouts under both operational modes. The P6P winding layout outperforms the D3P in the propulsion mode, offering a6% torque density enhancement, and in the charging mode, offering a much lower radial force.