VSI lossy models for circuit simulation including high-impedance state

The paper shows how blanking time and high impedance state can be incorporated, both in the instantaneous-value and averaged-value versions of the power balance based inverter model, by introducing only one more parameter and little modifications of the related equations, without altering the models structure and retaining their unique feature that allows to separately handle lossless behavior, conduction losses and switching losses, using a reduced parameters set. This result is obtained by defining a three-level switching function, in order to consider the additional control signals state, and a three-level signum function, to account for the zero condition on the AC current (besides its positive and negative polarity). Zero condition on both functions, along with the zero band of the signum function, are exploited to put the inverter output in the high impedance state, from which it is removed when the AC current exceeds its zero band. Furthermore, due to the more complete expression of the modulation index, also the blanking time can be incorporated in the instantaneous-value version of the model. Simulations carried out by means of the free of charge and widely used PSpice student version show the effectiveness of the proposed solution.