Advanced Control of GaN Y-Inverter for Traction Motors

Abstract

The cascaded buck–boost Y-inverter is a promising DC–AC converter topology due to its capability to accept a wide input DC voltage range while producing near-sinusoidal output AC voltages. The advantages of the Y-inverter can also be leveraged for electrified powertrains fed by fuel cells. As the power levels of such powertrains may exceed hundreds of kW, it is essential to minimize the size of the reactive elements required by the Y-inverter. This aim can only be achieved by increasing the switching frequency. By leveraging the unprecedented switching performance of gallium-nitride (GaN) transistors. The control solutions available in the literature for the Y-inverters are mostly based on a conventional cascaded voltage and current control, employing proportional–integral (PI) controllers in stationary frames. However, these solutions have limited bandwidth performance when the switching frequency is roughly lower than one hundred kHz, as may occur for traction inverters. Therefore, this article proposes an advanced control that is tailored for high-performance torque control of traction motors fed by GaN Y-inverters. It exploits rotating reference frames for voltage control and deadbeat control to enhance the dynamic control performance. The proposed solution has been successfully tested on a reduced-scale GaN Y-inverter supplying a permanent magnet synchronous motor for light traction.