A Hysteresis Current Controller PWM Scheme Applied to 3-Level NPC Inverter for Distributed Generation Interface
Ravi Varma Chavali, Anubrata Dey, Biswarup Das
Abstract
In this paper, a novel Pulse Width Modulation (PWM) technique is proposed for an existing space vector hysteresis current controller (SVHCC) scheme. A 3-level neutral point clamped (NPC) inverter is used for dual purpose of shunt active power filtering and solar photovoltaic (PV) power integration to a distribution grid. This dual-purpose NPC inverter utilizes the proposed PWM technique for solving neutral point voltage balancing issue in a unique way. Due to the inherent advantages of SVHCC, the current control is characterized by fast action and optimal switching. A single reference current required for both filtering and maximum PV power integration is generated using instantaneous power theory, where a diode bridge rectifier load is considered to demonstrate the controller performance while compensating non-linear current components. Thus, a unique space vector based PWM technique is not only adopted for fast-tracking of currents, but also a sliding current error boundary is used for the first time. This sliding technique tackles the DC-link balance issue of the NPC inverter while controlling the output currents simultaneously. The simulation and hardware results prove the above mentioned performance and demonstrate the efficacy of the proposed PWM current controller.