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An advanced symmetrical voltage quadrupler rectifier (SVQR) is derived in this paper to serve as the secondary rectification topology, which helps to extend the converter voltage gain and reduce the output diode voltage stresses. The output voltage is four times of the conventional full-bridge voltage rectifier with the same transformer ratio, which benefits to reduce the turns ratio of the transformer and decrease the parasitic parameters. Also low voltage-rated diodes with high switching performance can be applied to improve the efficiency. Meanwhile, all the diodes in SVQR have the same voltage and current stresses, which simplifies the thermal design. Furthermore, two output electrolytic capacitors are connected in series to share the high output voltage, and the voltage balance can be realized naturally without any additional voltage-sharing scheme. A clear picture is made in this paper to give a general framework and universal applications for the derived SVQRs for high step-up and high output voltage conversion systems. A dual boost converter is used as an example to demonstrate the clear advantages of the derived symmetrical voltage quadrupler rectifiers (SVQRs).Index Terms -Boost, High step-up, Symmetrical voltage quadrupler rectifier. . His research interests include high efficiency power converters and renewable energy power conversion system. Dr. Li has published more than 70 technical papers and holds more than 20 issued/pending patents.Xiangning He (M'95--SM'96--F'10) received the B.Sc. and M.Sc. degrees from Nanjing University of

Switched reluctance motor (SRM) drives are one competitive technology for traction motor drives. This paper proposes a novel and flexible SRM fault-tolerant topology with fault diagnosis, fault tolerance, and advanced control functions. The converter is composed of a single-phase bridge and a relay network, based on the traditional asymmetrical half-bridge driving topology. When the SRM-driving system is subjected to fault conditions including open-circuit and short-circuit faults, the proposed converter starts its fault-diagnosis procedure to locate the fault. Based on the relay network, the faulty part can be bypassed by the single-phase bridge arm, while the single-phase bridge arm and the healthy part of the converter can form a fault-tolerant topology to sustain the driving operation. A fault-tolerant control strategy is developed to decrease the influence of the fault. Furthermore, the proposed fault-tolerant strategy can be applied to three-phase 12/8 SRM and four-phase 8/6 SRM. Simulation results in MATLAB/Simulink and experiments on a three-phase 12/8 SRM and a four-phase 8/6 SRM validate the effectiveness of the proposed strategy, which may have significant economic implications in traction drive systems. Index Terms-Fault diagnosis, fault tolerance, switched reluctance motor (SRM), traction motor drive. NOMENCLATURE D PWM duty cycle. i a , i b , i c Currents for phases A, B, and C. i max Phase current peak when faulty. i max Phase current peak when normal. Δi Hysteresis window. N r Rotor poles. K L Inductance slope when normal. K i Current slope when normal. K L Inductance slope when faulty.

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