An approach of unified voltage correcting algorithm for SVPWM overmodularion

This paper presents a new unified algorithm used for voltage regulation of an inverter operating in overmodulation area of Space Vector Pulse Width Modulation (SVPWM). Overmodulation operation of the proposed strategy is based on a simple amplitude-phase correcting method, which modifies properly the amplitude and the phase angle of the output voltage. The unified Voltage Correcting Function (VCF) is piecewise continuous in entire SVPWM area and symmetrical in each sector with respect the angle π/6 enabling continuous transition from the linear modulation up to the six-step mode. A Fourier series expansion of the compensated phase voltage waveform is also presented. Simulation results are provided to demonstrate the effectiveness of the proposed SVPWM overmodulation method exploring the inverter voltage and motor currents response via Fast Fourier Transform (FFT) and Total Harmonic Distortion (THD) analysis. The new overmodulation algorithm has been applied on sensorless speed control scheme of a salient-pole Synchronous Machine (SM) with rotor field winding.