Research on Hybrid-Active EMI filter for DC/DC converter

The development of high-frequency and high-power DC/DC converters makes the current and voltage of the power switch change rapidly, which causes Electromagnetic Interference (EMI) in the power supply system. EMI is becoming more severe, which poses a major challenge to the bandwidth and Insertion Loss (IL) of EMI filters for processing noise. High insertion loss and wide band make EMI filter increasing in size, weight and cost. Active EMI filter adopts noise compensation scheme to avoid the application of large inductors, capacitors and other devices, and effectively reduce the size and weight. Because the active EMI filter adopts the closed-loop compensation method, the high insertion loss and the system stability index contradict each other in the wide frequency band, in this project, a Hybrid-Active EMI filter (H-AEF) is developed by using the technical scheme of Feedback Current-Sense Current-Compensation (FB-CSCC). Compared with the Passive EMI Filter (PEF), the size of the filter is reduced by 3 times while the insertion loss is higher; the active EMI Filter system has a 40% gain and an 11% phase allowance increase compared with the active EMI Filter in literature 8; compared with the conventional active EMI filter system with the same gain, the topology phase margin is increased by 7 times; the common-mode insertion loss reaches 44.7 dB at 200 kHz, and is matched with the 28 V bus voltage DC/DC converter, conducted noise CE102 meets the standard requirements.