High Frequency Modeling of DC/AC Converters

The paper proposes a new method to measure the High Frequency (HF) current components in electronic converters and defines a model able to address the converter operation on a wide frequency range (100 kHz ÷ 30 MHz). The developed model is calculated by an automatic procedure that performs the measurements during the normal operations of the converter, instead of using HF circuital sub-models of the power devices, that are only related to the parasitic inner parameters, connection wires, and diodes. By this approach, the HF admittance of the converter is calculated taking into account the instantaneous switches configuration and, therefore according to the switching PWM strategy. The proposed dynamic HF model of the power converter is composed by several black boxes, each related to a single converter status or a groups of states with the same response. Each box acts differently to a HF voltage excitation, according to the number of devices that are contemporary on and off, while the converter is modulated. By knowing the PWM modulation strategy, the sequence of the states is unambiguous and therefore the model of the converter is entirely defined. Simulations and experimental results are presented in order to evaluate the consistence of the proposed approach.