Development and implementation of a voltage harmonic elimination method for the single-phase inverter operating with nonlinear load

Single-phase inverters are widely used in power conversion systems. When operating with linear loads, these inverters produce regulated quasi-sinusoidal output voltages. When feeding nonlinear loads, they absorb non-sinusoidal (distorted) currents and the inverter’s output voltage deteriorates – it contains high levels of harmonics. This paper presents a method to reduce the harmonics in the output voltage. The control strategy is based on selective harmonic elimination – the method eliminates some of the low order harmonics of the output voltage. The method uses stationary reference frame voltage and current controllers. The voltage controller regulates the fundamental and eliminates certain harmonics using a modulation-demodulation technique. In the paper, the 3rd, 5th and 7th harmonics are eliminated. However, the scheme can be expanded to eliminate more higher-order harmonics. It is shown that the control proposed, significantly reduces the total harmonic distortion of the inverter’s output voltage, from 5.8% to 1.64% (at full load).