Fast Simulated Frequency Response Measurement for Switched-Mode Power Circuits

Abstract Modelling and simulation of electric circuits of switched-mode power converters provide the means for computer-based testing before an engineering prototype is manufactured. The topologies of the electric power conversion systems are typically highly complex and the analytical models may become difficult to derive. For such cases, non-parametric frequency-response modelling provides an efficient analyzing tool. The prevailing techniques provide methods to simulate time-domain behaviour of non-linear models of circuits and means to generate frequency responses of linearized small-signal models. Some tools provide also methods to calculate frequency responses of non-linear models. However, they are all based on sine-sweep method which requires a long simulation time. The measurement time can be drastically reduced by applying a broadband excitation signal. This paper presents a frequency-response measurement scheme for switched-mode converters where the sine sweep is replaced by the maximum length binary sequence (MLBS) excitation. The technique allows the design engineer to benefit from accurate frequency responses based on nonlinear modelling while shorter simulation time gives the opportunity to iteratively simulate the effect of parameter variations.