Active Loss Balancing Scheme with Decision Chart for 3L-ANPC-VSCs with IGBTs for Bidirectional Energy Flow Operation

An active loss balancing (ALB) scheme for the three-level active neutral point clamped voltage source converter (3L-ANPC-VSC) with insulated gate bipolar transistors (IGBTs) is presented in this work. This scheme is based on a decision chart which selects one of the four redundant zero states in terms of the estimated junction temperatures of the power semiconductors, which allows to actively select the most suited state in terms of losses. The decision chart is simplified by using a temperature multiplexer which defines the temperatures to be compared in terms of the voltage and current sign, and two decision charts were compared, one of them based on previous works, and the other one as an improvement. The simulation results show that, in generation operation (voltage and currents in counterphase), the improved proposal has a better performance in terms of maximum junction temperatures, while in motor operation (voltage and currents in phase), both charts have the same performance.