Modified PWM with a new indirect current control technique applied to a single-phase shunt active power filter MLI modifi´ ee avec une nouvelle commande indirecte en courant appliqu´ ee ` a un filtre actif shunt monophas´ e

This paper presents a novel pulse-width modulation (PWM) control technique applied for current regulation of a single-phase shunt active power filter. The technique is based on the indirect current control strategy. The control system is implemented successively with a standard PWM (S-PWM) and a new modified PWM (M-PWM) to compensate the current harmonics and the reactive power produced by a nonlinear load. The linear regulators are chosen using a frequency-domain model of the filter that is elaborated by a small-signal modelling technique. The M-PWM control technique is based on comparison of a triangular high-frequency carrier signal with the low-frequency load-current fundamental component and its opposite. The M-PWM shifts the first significant-harmonics rays towards twice the switching frequency. Furthermore, it eliminates the spectral rays which are centred on the odd multiples of the switching frequency. Simulation and experimental results obtained on a 1kVA laboratory prototype are presented to verify the better performance of the M-PWM compared to the S-PWM and its superiority in terms of total harmonic distortion and reactive power compensation.