Low Loss Multi-Ring Shielding Technique for Multiturn PCB Winding Transformer

Inserting shielding layer is an effective method to attenuate the common-mode (CM) noise induced by the large interwinding capacitance of printed-circuit-board (PCB) winding, however, the existing shielding technique cannot achieve the suppression of CM noise in multiturn winding per layer configuration, and there is a large eddy current loss. A low loss multi-ring shielding technique for multiturn PCB winding transformer is proposed in this letter. Under the premise of adopting multiturn winding per layer configuration to effectively reduce the number of PCB layers, the proposed multi-ring shielding technique can effectively suppress the CM noise by around 16 dB. Furthermore, the eddy current loss can be effectively reduced by optimizing the rings number of the multi-ring shielding. Experiment results on a 150 kHz 1000 W 18–36 V input 360 V output current fed dual active bridge (CF DAB) converter validate that, compared with typical shielding method, except for similar shielding performance, the proposed multi-ring shielding technique can improve power density by 67%, reduce the shield eddy current loss by 77.7% and improve the peak efficiency by 0.31%.