Algorithm for near optimal harmonics elimination PWM based on quadratic approximation method

Harmonic elimination optimized pulse-width modulation (HEPWM) scheme has been recognized as an attractive alternative to sinusoidal modulated PWM schemes for voltage source inverters (VSI). However, its application has been limited by the fact that the switching angles cannot be calculated online by a microprocessor-based waveform generator, as the equations involved are nonlinear and transcendental in nature. The paper proposes an algorithm to calculate near optimal switching angles, which will permit a fast and efficient realization using a microprocessor. The method is based on quadratic approximation approach which is derived from the computed trajectories of angles. The results indicate that the proposed method is accurate enough to substitute for the original harmonic elimination equations.