Network CM EMI Reduction Using Sinusoidal Frequency Modulated Carrier Wave Indexing

There is a growing concern regarding the accumulation of common-mode (CM) electromagnetic interference (EMI) in large networks of power converters. Multi-converters operating in parallel may produce EMI that exceeds EMI limits even when each converter complies with EMI standards. Generally, industries utilize EMI filters or shields/chokes to mitigate EMI emissions. These solutions are not optimized for network environments as they are designed for individual converters. Thus, this paper presents a novel algorithm for suppressing CM EMI in a large-scale network using sinusoidal frequency modulated carrier waves (SFMCWs) indexing. This method minimizes switching frequency overlap among converters to reduce aggregate EMI. In experiments using GaN switching devices, EMI was attenuated by [5-15dBuV] for two parallel half-bridge inverters. This method reduces the output of network CM EMI without re-designing or adding additional filter devices that would increase weight, volume, or form factor.