A State-Space Approach to the Modelling and Control of the Neutral Leg of a Four Legs, Three-Phase Inverter

Abstract

In this paper, a novel approach to determine the model of an ICNL (Independently Controlled Neutral Leg) is proposed. Based on this model, a cascaded control method is developed to provide a steady neutral point connection for a three-phase four-wire inverter and to balance the two DC capacitors voltages of a split DC-bus. Validation of the model is realised by simulations and the control has been tested by experiments. Results have shown good performance even with a high level of neutral current, which demonstrate the ability of the system to work within an unbalanced load or grid.

SiC-Based EV Charger for DC Bus Second-Order Ripple Reduction

“…The main advantage of having an independently controlled neutral leg is the reduction in complexity of the control scheme, as the control of the phase legs and the neutral legs is independent. This also prevents EMI in the dc and ac terminals [19]. The use of a four-wire inverter for automotive applications was presented in [20], where the independently controlled neutral leg enabled relieving the imbalance issues on the split capacitors.…”