Fast frequency response measurement of switched-mode Converters in the presence of nonlinear distortions

Switched-mode converters have become extensively used in powering different consumer products. The increased mass production using low-cost components with high parameter variation has set new challenges to designers. Recent studies have shown that frequency-domain characterization yields most useful information about the dynamics and quality of the converter. This has been widely recognized and fast correlation techniques have been developed to make appropriate frequency response measurement to be applied both in design and production phases. These techniques are based on appropriate broad-band excitation signal which is injected into a converter and its response is measured and analyzed. All the previous papers have used pseudo-random binary sequence (PRBS) as the excitation. The conventional binary sequence do not, however, suit well for the processes suffering from strong non-linear distortions. This paper proposes a new type of excitation signal which can be used similarly to the conventional PRBS but provides much more accurate frequency response estimates. Inverse-repeat binary sequence (IRS) is applied to minimize the effect of different nonlinearities and the frequency response is measured by means of spectrum method. The method is verified both with simulation and practical measurements and the results are compared to the conventional PRBS technique.