Modeling and performance evaluation of filtering components for switch-mode power supplies based on piezoelectric effect

Traditional passive electromagnetic interference (EMI) filters typically need to use common-mode chokes with high inductance values to ensure that switch-mode power supplies (SMPSs) meet relevant electromagnetic compatibility (EMC) standards. This approach not only increases the weight and size of SMPSs but also reduces their power density. To address these issues, this article proposes a method for modelling and performance evaluation of filtering components for SMPSs based on piezoelectric effect. Piezoelectric filtering components (PFCs) possess low impedance properties at their resonant frequency, while outside of resonance, their impedance is similar to that of a capacitor. As a result, PFCs can not only serve as replacements for traditional interference suppression capacitors (e.g., Y-capacitors) used in passive EMI filters but also effectively suppress interference peaks at specific frequencies. Based on the impedance properties of PFCs, this article proposes a resonant frequency design model. This model can precisely tune the multiple resonant frequencies of PFCs by adjusting their shapes and sizes, thereby leveraging the resonant properties of PFCs to selectively suppress interference peaks at multiple specific frequencies in SMPSs. This article applies the PFCs to the flyback converter and investigates their conducted EMI suppression effectiveness. According to the measurement results, compared to the Y-capacitors, the PFCs reduce the weight and volume of the passive EMI filter by 88.72% and 90.71%, respectively. The experimental results indicate that, based on the model developed in this article, using PFCs as a filtering component can lead to a lighter and more compact filter design.