International Journal of Engineering Research in Electrical and Electronic Engineering (IJEREEE)

Fuzzy Controller for Circulating Current in Parallel Three Phase PWM Converters under Generalized Unbalanced Operating Conditions

Author : M. Madhavi ¹ R. Madhavi ²

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Date of Publication :20th September 2017

Abstract: The use of common dc-link parallel three-phase PWM converter topology owing to advanced features & applications has become more popular, This paper proposes another control scheme for parallel three phase pulse width modulation (PWM) converters under generalized lopsided working conditions. When three-phase PWM converters are connected in parallel there exist circulating current, which result in current distortion and harmonic loss in parallel module and degrade the overall performance of the parallel system. An average model of the parallel system in positive-sequence synchronous reference frame (PSRF) is derived to dissect the impact of generalized unequal working conditions in AC side. It is seen that the variance in network frequency & the unbalance factors in filter inductance won't just offer ascent to negativesequence circulating current, additionally add to creating zero-sequence circling current (ZSCC) with the coupling between the active-reactive system. The negative-sequence circling current can be restrained by suppressing the negative-sequence parts in AC output currents of parallel modules with a proportional integral resonant (PIR) controller. An enhanced feed forward system and a fuzzy controller for ZSCC control are proposed for unequal working conditions. The unsettling influences in ZSCC caused by unbalance factors in filter inductance can be rejected with feed forward methodology. The proposed plan with a PIR, Improved feed forward & fuzzy controller can successfully stifle the circulating currents between the parallel modules and therefore, the distortions in output currents can be enormously diminished..

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