A 24V-to-20V 6W 73.2%-Peak-Efficiency Isolated DC-DC Converter Using a Transformer-Based Supply-Generating Technique

SiC or IGBT power devices that have high breakdown voltages and large current capability are extensively used in applications like traction inverters and on-board chargers for electric vehicles (EVs). For these applications where PCB space and component height are premium, isolated DC-DC converters with high power density and high isolating rating are crucial for powering the gate drivers of these devices. Isolated converters that incorporate ferrite transformer and multiple components in a modular design operate at low frequency, typically in the tens of kHz range, achieving an efficiency of around 80% [1]–[3]. However, the inclusion of bulky and expensive transformers significantly degrades power density and increases cost. Recent advancements on integrated isolated converters using micro-transformer [4] or PCB substrate-based transformer [5] have greatly improved level of integration and reduced cost. Nevertheless, they are primarily suited for low-voltage conversions (e.g., 5V/5V), failing to meet the requirements of SiC or IGBT gate drivers that demand voltage levels of up to 20V. The only integrated solution targeted for high-voltage conversion is a commercial product reported in [6]. As shown in Fig. 1, by integrating all components into a small-outline integrated-circuit (SOIC) package, it achieves 57% form fact reduction when compared with [1]–[3], while the efficiency is degraded to 60%. In this work, a 24V/20V integrated isolated DC-DC converter featuring an efficient transformer-based supply-generating technique is proposed to achieve a peak efficiency of 73.2% and a power density of 36.SmW/mm3, representing a major improvement over the performance reported in [6].