Electromagnetic Energy Conversion Efficiency Enhancement of Switched Reluctance Motors With Zero-Voltage Loop Current Commutation

Zero-voltage loop (ZVL) commutation in switched reluctance (SR) motor operation can result in a significant improvement of their performance by lowering the flux-linkage peaks and harmonic magnitudes of the magnetic flux densities within the core of the SR motor. The efficiency enhancement provided by ZVL commutation, especially in high-speed SR motoring has not been thoroughly investigated to-date. This paper investigates the energy conversion efficiency of SR motors with ZVL current commutation. The lowering of core losses is investigated with finite element modeling of a 250 kW 12/8 SR motor. An enhancement of efficiency in the ranges of 0--3% and 0--5% is computed considering operation below base-speed and above base-speed respectively. The effect of core material on the ZVL commutation performance is also investigated for the 250 kW 12/8 SR motor. The increase of efficiency with ZVL is further validated with experimental results on a 300 W 6/4 SR motor which achieves an enhancement in the range of 2-6%.