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This paper presents an integrated multilevel converter of switched reluctance motors (SRMs) fed by a modular front-end circuit for plug-in hybrid electric vehicle (PHEV) applications. Several operating modes can be achieved by changing the on-off states of the switches in the front-end circuit. In generator driving mode, the battery bank is employed to elevate the phase voltage for fast excitation and demagnetization. In battery driving mode, the converter is reconfigured as a four-level converter, and the capacitor is used as an additional charge capacitor to produce multilevel voltage outputs, which enhances the torque capability. The operating modes of the proposed drive are explained and the phase current and voltage are analyzed in details. The battery charging is naturally achieved by the demagnetization current in motoring mode and by the regenerative current in braking mode. Moreover, the battery can be charged by the external AC source or generator through the proposed converter when the vehicle is in standstill condition. The SRM-based PHEV can operate at different speeds by coordinating the power flow between the generator and battery. Simulation in MATLAB/Simulink and experiments on a three-phase 12/8 SRM confirm the effectiveness of the proposed converter topology. Index Terms-Fast excitation and demagnetization, front-end circuit, multilevel voltage, flexible battery charging, plug-in hybrid electric vehicle (PHEV), switched reluctance motor (SRM).

Reliability of power converters is of crucial importance in switched reluctance motor drives used for safetycritical applications. Open-circuit faults in power converters will cause the motor to run in unbalanced states, and if left untreated, they will lead to damage to the motor and power modules, and even cause a catastrophic failure of the whole drive system. This study is focused on using a single current sensor to detect open-circuit faults accurately. An asymmetrical half-bridge converter is considered in this study and the faults of single-phase open and two-phase open are analysed. Three different bus positions are defined. On the basis of a fast Fourier transform algorithm with Blackman window interpolation, the bus current spectrums before and after open-circuit faults are analysed in details. Their fault characteristics are extracted accurately by the normalisations of the phase fundamental frequency component and double phase fundamental frequency component, and the fault characteristics of the three bus detection schemes are also compared. The open-circuit faults can be located by finding the relationship between the bus current and rotor position. The effectiveness of the proposed diagnosis method is validated by the simulation results and experimental tests.

Abstract-Switched reluctance motors (SRMs) have been considered as low-cost machines for electric vehicle (EV) and hybrid electric vehicle (HEV) applications. However, the current sensors used in the system will not only increase the cost and volume, but also degrade the running reliability of the motor drives. Conventionally, the current sensors are used in each phase winding individually to obtain these phase currents. To reduce the number of current sensors, a four-phase 8/6-pole SRM is applied to analyze the working states and a novel phase current reconstruction method from the dc-link current employing double high frequency pulses injection is then proposed. Two kinds of high frequency pulses with large dutycycles and phase-shift are injected to the down-switches in each phase respectively when the phase currents are overlapped in the turn-on region, and the dc-link current is decomposed to reconstruct phase currents in both current chopping control (CCC) system and single pulse control (SPC) system. The transient performance in a closed-loop system based on the phase current reconstruction scheme is investigated. The proposed method uses only one current sensor in the dc-link and requires no additional circuits. The simulation and experimental results are presented to confirm the implementation of the proposed method.Index Terms-Switched reluctance motor (SRM), electric vehicle (EV), phase current reconstruction, high frequency pulses injection, single current sensor, dc-link current.

Switched reluctance motors (SRMs) are gaining in popularity because of their robustness, cheapness and excellent highspeed characteristics. However, they are known to cause vibration and noise primarily due to the radial pulsating force resulting from their double-saliency structure. This paper investigates the effect of skewing the stator or/and rotor on the vibration reduction of the three-phase SRMs by developing four 12/8-pole SRMs including a conventional SRM, a skewed rotor-SRM (SR-SRM), a skewed stator-SRM (SS-SRM), and a skewed stator and rotor-SRM (SSR-SRM). The radial force distributed on the stator yoke under different skewing angles is extensively studied by the finite element method (FEM) and experimental tests on the four prototypes. The inductance and torque characteristics of the four motors are also compared and a control strategy by modulating the turn-on and turn-off angles for SR-SRM and SS-SRM are also presented. Furthermore, experimental results have validated the numerical models and the effectiveness of the skewing in reducing the motor vibration. Test results also suggest that skewing the stator is more effective than skewing the rotor in SRMs.

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