This paper presents a common mode noise mitigation technique of a three-element resonant converter at its DC input terminal. Using an equivalent balanced LCL-T structure, that ensures symmetry for common mode (CM) noise propagation aided with a shielded transformer, the DC input emissions in the low frequency range (150 kHz to 30 MHz) are minimized significantly. Unlike traditional methods, the proposed technique is not limited to upper limit of common mode Y capacitors and relies on simple Wheatstone bridge balancing principle. The proposed circuit is demonstrated on a GaN based three level LCL-T converter used in On-Board charger applications switching at a fixed frequency of 500 kHz.
