Power converters design and experimental verification for electromagnetic contactors to reduce the impact of the voltage sag in the power system

This research aims to offer a power supply system based on power converters to supply electromagnetic contactors from the power distribution grid. Its primary purpose is to minimise the voltage sag impact on the contactor, eliminating the possibility of contacts tripping or excessive vibration. In addition to this, the contactor's inherent low power factor must be compensated, reducing the contactor's impact on the power grid. To complete these requirements, the power supply system comprises a Totem-pole PFC converter, a Buck converter stabilising the supplied voltage, and an H-Bridge, decreasing the switch-off commutation time. The research focuses on the converters' design methodology, supported by a case study and experimental verification. Considering the electromagnetic contactor characteristics, the system design requirements are systemised. The analytically and experimentally obtained data shows that based on the chosen converters' topologies, the suggested power supply system provides contactor stable operation in a wide input voltage range, acceptable power losses and high efficiency.