This article presents a new configuration of onboard integrated battery charger for electric vehicles (EVs) using six-phase machine and three-phase ac source. The configuration proposes the utilization of symmetrical six-phase open-end winding machine, twelve-leg inverter, and a dc-dc converter. The charger circuit is constructed by connecting directly the three-phase grid to the middle point of machine's phase winding, where the grid currents split into equal portions and flow in opposite directions, without adding an extra mechanical switch (or relay). From this concept, the proposed system has the advantages of obtaining high-power density with a large value of inductance for grid-side filter during charging and avoiding an electromagnetic torque as well as providing a high fault tolerant capability. Moreover, through proper control strategy, the proposed system is able to operate under unity power factor (UPF) with total harmonic distortion (THD) below 5%. In this article, the possibility of vehicle-to-grid (V2G) mode is also investigated. Detail of the control strategy for charging and V2G are given. Furthermore, simulation and experimental results are provided to validate the theoretical analysis.

The integration of nine-phase permanent magnet synchronous machines (9-PMSMs), employed in on-board integrated battery charger for electric vehicles (EVs), into three-phase grid generates an inevitable torque fluctuation in charging and vehicles-to-grid (V2G) modes. This undesirable torque which is source of motor vibration and noise, is due to the interaction between zero-sequence current, triplen harmonics (3rd and 9th) of induced back EMF and rotor position. This paper considers a new solution for nine-winding integrated battery chargers of EVs. A segmented three-phase PMSM with nine windings (S3-PMSM-9W) is used to replace the 9-PMSMs. With this configuration, the system has the advantage of torque-free in charging/V2G mode, low core loss, and simple control (based on three-phase control) in both traction and charging/V2G modes, with the privilege of employing reduced number of sensor and with no additional new elements. Through proper three-phase control strategy, the system operates under unity power factor (UPF) with total harmonic distortion (THD) below 5 %. Control strategies for charging, V2G and motoring are given, moreover simulation and experimental results are provided to validate the theoretical analysis.

A segmented three-phase interior permanent magnet synchronous motor (IPMSM) can bring a significant advantage in the development of electric vehicles (EVs) since it can be used as a simple inductor filter for an integrated battery charger without torque production during charging/vehicle-to-gird (V2G) mode. However, unlike an induction machine, majority of IPMSMs have low value of stator inductance, possibly below the minimum limit of the pulsewidth modulation rectifier requirement; therefore, the integrated battery chargers based on these types of IPMSMs may have difficulty dealing with grid current harmonics during charging/V2G mode. This article presents the method to design a suitable segmented three-phase IPMSM with nine windings (S3-IPMSM-9W) for integrated battery chargers. The optimization of stator winding inductance is proposed in order to get a large stator inductance capable of achieving acceptable ripple during charging and does not degrade the traction mode performance. Therefore, an optimized inductance, which is eight times greater than the nonoptimized stator inductance value was obtained. 96% of the efficiency of the optimized machine was achieved during the motoring mode. Moreover, with the help of optimized leakage inductance acting as a grid-side filter, the total harmonic distortion below 5% is reached during charging. Simulation and experimental results are provided to validate the theoretical analysis.

This paper proposes an integrated battery charger for electric vehicles (EVs) that combines a dual three-phase bi-directional converter (D3BC) and a segmented three-phase six-winding permanent magnet synchronous motor (S6-PMSM) into a single-phase charging system with high fault-tolerance capability. The charging circuit is created by connecting directly the single-phase grid to the motor winding terminals without modifying the motor. In this setup, the S6-PMSM functions as single-phase AC inductance filter (a combination of self- and mutual inductances), while the D3BC acts as a dual parallel single-phase rectifier (DP1R). In this proposed system, no additional devices (such as switches, etc.) are needed for the hardware reconfiguration that makes the system robust. Due to the magnetic interaction between rotor poles and stator slots, this context highlights the presence of cogging torque in PMSM during charging and vehicle-to-grid (V2G) operation. By parking the EVs with the rotor position at ± k π/ LCM ( N_poles , N_slots ), where k = 0, 1, 2, 3, and so on, a zero cogging torque is achieved. In charging/V2G modes, the proposed system operates with zero electromagnetic torque production, unity power factor (UPF), less than 5% total harmonic distortion (THD), and over 90% peak efficiency. A detailed theoretical analysis of S6-PMSM behavior in charging/V2G modes and its finite element analysis (FEA) is presented. The control algorithm with fault-tolerant control for the proposed integrated battery charger is provided. Experimental results are included to validate the theoretical analysis and simulations.

This article proposes a torque elimination in three-phase integrated dual-battery charger using a six-winding permanent magnet synchronous machine (PMSM) drive system. The proposed system can charge both a high voltage main-battery and low voltage secondary-battery from the reconfiguration of the motor drive and the existed half-bridge converter as dual battery charger. Due to the anisotropic characteristic of the motor windings’ inductance used as a grid harmonic current filter, an unbalanced current sharing can occur in stator windings during charging, which leads to torque production. In this article, a balanced current-sharing technique is proposed to cancel the charging torque and improve the performance of charging. The theoretical analysis of the charging current distribution within stator windings is conducted to determine the electromagnetic torques in both unbalanced and balanced current-sharing scenarios. The control algorithm, which is based on equal current sharing under different rotor positions, and winding-short-circuit-fault, is implemented. Simulation and experimental results are provided to validate the theoretical analysis.

This paper addresses the torque generated in a six-phase permanent-magnet synchronous machine (6PMSM) when it is reused as a three-phase integrated on-board battery charger in electric vehicles. The inequality stator-phase disposition produces unequal equivalent inductances among the windings, which unavoidably creates electromagnetic torque. A novel six-phase open-end winding topology is first introduced: during charging, both sides of every open-winding act as grid-side harmonic filters; under ideal balanced conditions, the two halves carry currents that are equal in magnitude and opposite in direction, so the counter-rotating fields cancel and no net torque is produced. However, this perfect condition is difficult to achieve in the real system in practice. More than a 5% difference (inequality) in stator winding inductance can be observed at different rotor positions. Consequently, a dedicated current-control strategy is developed in order to compensate the unequal inductance, force the winding currents back into balance, and thereby eliminate the undesired torque while providing additional harmonic attenuation. In the proposed charging mode, the system operates at 0.99 power factor with zero average torque and a total grid current harmonic distortion (THD) of 3.47%. Experimental results verify that the proposed topology and control algorithm successfully keep the 6PMSM torque-free even when the machine is operated as grid filter inductance.