Selective harmonic elimination in three-phase Current Source Inverter- A generalized approach

This paper presents a generalized technique for realizing PWM patterns which provides selective harmonic elimination (SHE) for Current Source Inverters (CSI). The selective harmonic elimination method for CSI is generally based on independent chop angles between 0 and 30´. The conventional SHE method cannot handle more than a few harmonics as chop angles are always restricted to be in 0 and 30´. In this work, a combination of chops as well as short circuit pulses are utilized to selectively eliminate lower order harmonics with minimum switching frequency. For SHE method, the switching angles were determined using resultant theory and symmetric polynomials by solving the nonlinear transcendental equations. Using these switching angles, the elimination of two harmonics (5 and 7, 5 and 11, 5 and 13, 7 and 11, 7 and 13) have been successfully carried out along with suitably placed shorting pulses. This is an improvement over existing techniques. This can be extended to any arbitrary number of harmonic elimination. The simulation of the proposed work has been carried out using MATLAB/SIMULINK software.