Current Sensorless Online Capacitor Parameter Estimation Method in Buck Converters Based on Large Signal Profile Considering Magnetic Saturation

Large signal profiles are commonly utilized for estimating capacitor parameters in power converters, which typically requires current information. Installation of current sensors in practical power converters could be inconvenient and expensive. Existing current sensorless methods calculate the current based on voltage measurements. However, the ignorance of magnetic saturation of inductors could cause large current calculation errors, which propagate to the capacitor parameter estimation results. For buck converters, this paper proposes a current sensorless capacitor parameter estimation method that fully considers the magnetic saturation of inductors. Initially, the relationship between magnetic flux linkage and inductor current is modeled as a piecewise polynomial function, to achieve accurate extraction of currents using voltage measurements during magnetic saturation. Subsequently, the equivalent series resistance and capacitance of the capacitor are rigorously derived and analytically expressed by voltage measurements only. Simulations and hardware experiments confirm the effectiveness and accuracy of the proposed method.