GaN-FET-based PWM power stage and breakout board for single-phase electric drives as open source hardware

A pulse-width-modulated power stage with current measurement was required for a highly dynamic force-compensated motion system with a projected acceleration of 100 m/s². As no suitable system was available on the market, an in-house solution was developed using the open-source EDA software KiCAD and made available to the scientific community as open-source hardware. The design relies on commercial half-bridge evaluation boards with modern Gallium-Nitride transistors (LMG341x) from Texas Instruments. It includes motherboards with control logic and current measurement, as well as breakout boards for connection to the controller. Development aimed for switching frequencies of 100 kHz, with a nominal voltage of up to 100 V and 10 A RMS. One main aspect was electromagnetic compatibility: communication between the breakout board and half-bridge-motherboard takes place via fibre optics, and the current measurement signal is transmitted as differential voltage. The breakout board can connect with any controller via 5 V TTL logic – in our case a rapid control prototyping system from dSPACE. In the paper, we present the objective, circuit design, validation, and potential of our system. Subsequently, we will discuss the errors made during development and demonstrate how to swap back mixed-up pins elegantly.