Pulse-test for wireless power transfer systems: A special feature for resonance frequency determination

Due to the rising electrification, there is a need for innovative charging technologies to keep pace with technological progress and tethered charging. The electrical performance of wireless power transfer (WPT) systems is one crucial point in charging electric vehicles. The resonance frequency respectively the switching frequency of the converter has a large impact on system behavior. Due to component and manufacturing tolerances and the power transmission over distance, displacement and angle change of the two coils the resonance frequency of the system changes. Adapting the switching frequency is a common and effective way to ensure high-level efficiency. This paper proposes an innovative method to determine the resonance frequency of the WPT resonance circuit using the converter. In a first step, by measuring the systems pulse response with an oscilloscope (f_osc), the resonance frequency can be calculated, based on an excitation of the system with voltage pulses of certain level and extent.