Compact PCB Coil-based Bilateral Inductive Power Relay System Powering Multiple Gate Drivers with Reliable Voltage Isolation

Series-connected semiconductor switches in high-voltage applications generally require isolated power supplies for their gate drivers. This paper proposed a compact inductive power relay system to concurrently power multiple gate drivers with reliable voltage isolation. Compared to existing solutions, there are three improvements. First, printed circuit board (PCB) based coils are used to replace the ferrite-based Litz-wire coil, achieving low cost and light weight. Second, all coupled coils are designed in a unipolar geometry, enabling smaller coil dimensions than bipolar coils used in other solutions. Third, all the load units have identical circuit configurations and parameters, achieving good unit consistency. Detailed system design and analysis are provided, and a prototype is implemented with a coil size of 120mm×70mm to power the gate drivers of four series-connected high-voltage thyristor modules. Experimental results show consistent voltages of 18V are achieved in four output channels, validating the effectiveness of the proposed system.