Six-phase induction machines have mostly shown promise in high-power electric drive applications as well as wind energy conversion systems. Different winding configurations for six-phase stators have been published, namely, dual three-phase (D3P), symmetrical six-phase (S6P), and asymmetrical six-phase (A6P) winding layouts. Although a body of research investigating six-phase machines and their control for different six-phase winding arrangements exists, a thorough comparative study between these different arrangements in terms of machine parameters and performance, has not been done so far. This paper employs a 12-phase stator with a configurable terminal box to compare different six-phase configurations by simply reconnecting the stator terminals of the twelve phases in different manners to obtain an equivalent six-terminal stator. This way, the same stator machine dimensions and copper volume will be assumed for all connections. The comparative study focuses on the effect of winding connection on machine parameters of the different subspaces, phase current quality and machine characteristic curves. Experimental validation has been carried out using a 1kW prototype system.

This article presents the operation of onboard integrated battery chargers tied to a nine-phase EV-drive train, shedding light on the charging performance during the postfault operation, when one or more faulty inverter legs are disconnected. The objective in that case is to ensure balanced grid currents, while maintaining minimum machine losses at zero average torque production. The proposed concept requires a minimalistic change from a control structure perspective to switch between the pre- and postfault cases. Limitations and fault cases are discussed and corroborated with experimental tests on a 1.5-kW prototype.The derived concept is parameter independent and applicable to nine-phase drives, irrespective of the type of rotor used.

Integrated on-board battery charging (IOBC) constitutes one of the future trends and the potential state-of-the-art technologies proposed for high-power chargers of electric vehicles. Model predictive control has recently been favored in different applications due to its simplicity in defining new control objectives and the straightforward handling of nonlinear constraints. In this article, the predictive current control (PCC) is applied to a six-phase induction-machine-based IOBC with three different winding configurations. From the grid perspective, this article introduces the required winding connections that maximize the charging grid current. Under PCC, different stator phases are controlled to draw balanced three-phase grid currents through controlling the machine nontorque-producing xy current components while ensuring zero average/ripple torque production. This article also discusses the effect of winding configuration on the mapping of the 64 available voltage vectors to the αβ , xy , and 0⁺ 0⁻ subspaces. The optimal subset voltage vectors of each configuration that achieve the highest possible dc-link utilization, zero torque production, minimum total harmonic distortion (THD), and unity power factor are then introduced. The feasibility to employ the concept of virtual voltage vectors to improve the current quality is also investigated. The three six-phase configurations are obtained from an externally reconfigured 1 kW 12-phase induction motor, which has been used to experimentally validate the theoretical findings.

Electric vehicles (EVs) play a major role in the evolution towards sustainable transportation. The integration of information and communication technology (ICT) into the electric vehicle (EV) charging process has witnessed rapid progress. Wireless communication between EVs has become commercially viable, supporting vehicle-to-sensor, vehicle-to-vehicle, and vehicle-to-internet regimes. However, EVs still have limited market penetration due to charging process constraints such as charging time and the availability of charging points. This paper considers an asymmetrical nine-phase smart integrated on-board charging (OBC) system with a reduced cost, size and weight. All the propulsion components are utilized in the charging process. Both zero machine average torque production and unity power factor operation at the grid side can simultaneously be obtained during the charging process. Additionally, no hardware reconfiguration is required to allow the transition between propulsion and charging modes for this system topology. Furthermore, the proposed integrated on-board charger is completely monitored, and the charging rate is controlled through a smartphone application via internet of things (IoT) technology, thus optimizing the user experience. A 1.5 kW prototype is implemented to validate the proposed system by rewinding a three-phase induction motor (IM).

Multiphase drives exhibit remarkable advantages (e.g., fault tolerance) over three-phase ones. Six-phase drives are particularly attractive, given their moderate complexity and suitability for off-the-shelf three-phase converters. Regarding the stator winding arrangement, the symmetrical one offers superior postfault capabilities in most scenarios. On the other hand, resistance asymmetry in the stator phases or connections may arise due to different causes. The conventional full-range minimum-loss strategy (FRMLS) generates stator-current references under open-phase (infinite resistance) faults so that torque ripple is prevented while minimizing the losses for each torque ( $\boldsymbol{d}$ - $\boldsymbol{q}$ current) value and maximizing the torque range; however, this method is unsuitable for unequal resistances of finite value. This article proposes an FRMLS for setting the current references to reach these goals in symmetrical six-phase drives with any resistance asymmetry. The optimum references are found online depending on the resistances, without lookup tables. The phase currents are individually limited by an iterative algorithm, so that minimum stator copper loss (SCL) is achieved over the maximum admissible torque range. In this manner, unlike the conventional FRMLS, minimum SCL and maximum torque range are attained even for finite resistance imbalance. The currents in phases affected by high resistances are suitably reduced. Experimental results are provided.

Multiphase machines are often chosen due to their enhanced fault tolerance. Six-phase ones are especially convenient because they may be fed by off-the-shelf three-phase converters. In particular, those with symmetrical windings offer superior postfault capabilities. On the other hand, estimation of the stator resistance is important for purposes such as thermal monitoring and preserving control performance. Resistance estimation by dc-signal injection provides low sensitivity to parameter deviations compared with other techniques. It has previously been shown that the dc signal can be added in the nontorque-producing ( $x$ – $y$ ) plane of a six-phase machine to avoid the torque disturbances that typically arise in three-phase machines. However, extending this method to the case of an open-phase fault (OPF) is not straightforward because of the associated current restrictions. This article addresses dc-signal injection in a symmetrical six-phase induction motor with an OPF. It is shown that, in contrast to healthy operation, the postfault dc injection should be carefully performed so that minimum copper loss, peak phase current, and zero-sequence braking torque are achieved. A solution that attains optimum performance in all these aspects simultaneously is proposed. Adapted controller and resistance estimation are also presented. Experimental results confirm the theory.