Combined RCD, power manager and phase-switcher for electric vehicles charging, controlled by an FPGA

Abstract: This master thesis investigates the subsystems required to create a combined residual-current device, power manager and phase-switcher for electric vehicles charging, controlled by an FPGA. The purpose of this task is to create a prototype design for Chargestorm, a company that manufacture charging stations for electrical vehicles and provides a portal for payment. Each subsystem will be separately investigated to see the available alternatives and evaluate which solutions fit this design best. The system is designed to handle currents of 32 A on three phases. The design consists of a hall sensor to detect the residual current, switches to meet the switching requirements and to break the circuit when needed, current transformers to measure current and differential amplifiers to measure voltage. All logic and communication is controlled by an FPGA. Specific isolation requirements are set to prevent the power grid from arcing to the low voltage components. Optocouplers are used to allow communication between the components on the high voltage and the low voltage sides. The final design is placed on a six layer printed circuit board. This is mainly to allow for more copper to conduct the high current and thermal management. Theoretically, the work is complete and all requirements are fulfilled. In practice however, the prototype have not been fully tested and evaluated to see if the theory matches the real world.