Reducing EMI Filter Size and Losses with a Novel Piezoelectric Interference-Suppression Component

Switch-mode power supplies (SMPS) are one of the main sources of electromagnetic interference (EMI). Suppressing EMI with minimal filtering effort results in a multifaceted challenge for hardware developers. To overcome this challenge, a novel EMI measure for SMPS based on the piezoelectric effect will be presented. Piezoelectric interference-suppression components (PISCs) provide a low-impedance propagation path at their resonance frequencies. Beyond their resonance frequencies, PISCs feature a capacitive behavior. PISCs can, therefore, not only replace interference-suppression capacitors, such as Y-capacitors, but also provide selective attenuation at certain disturbance peaks. It will be experimentally shown that a more compact EMI filter can be realized by utilizing PISCs. As an application scenario, PISCs are implemented in a flyback converter and their EMI suppression is investigated. Experimental results validate that the proposed filtering method can achieve a 64 % volume reduction and a 54 % reduction of DC losses within the filter compared to conventional EMI measures.