Study and Development of a Control Loop Implementation for a Low-Power Capacitively Isolated DC-DC Converter

This thesis continues the analysis of a Capacitively Isolated Low-Power DC-DC converter, building on previous work, by incorporating a control loop to regulate the output voltage under varying conditions and maximizing the system’s performance. To achieve this, a comprehensive mathematical model is develop to better understand the system’s behaviour and dynamics. The operating point is carefully selected to optimize performance by exploiting the sub-harmonics in the gain curve and Partially Damped Oscillations (PDO). This approach significantly reduces switching losses and ensures Zero Voltage Switching (ZVS) across all operating points. Various control strategies are presented, highlighting the advantages and disadvantages of each. The strategies include frequency-based control, duty cycle-based control, bang-bang control and dyadic pulse modulation control. The system is designed as a consumer electronics power adapter, capable of delivering 50W of output power at a constant 20V output voltage with an efficiency greater than 85%.