Ing. Filipp Frolov

Current collapse in gallium nitride based transistors limit their use in high power and high frequency converters. In some cases, it makes the conduction losses to double. This paper investigates the measurement of dynamic on-state resistance for various cases such as blocking voltage and switching frequency. The optimum minimal length of pulses was determined in the case of three phase inverter to minimize the influence of current collapse.

This paper presents a design of a high efficiency and high frequency synchronous buck converter based on GaN devices. Gallium Nitride (GaN) FETs are applied in this design to achieve the low power losses at high operation frequency. Synchronous buck topology is used to increase the system efficiency and reduce conduction losses. Converter is tested in several frequencies 100, 200, 400 kHz. The paper also contains the theoretical analysis of power losses in the converter. A synchronous buck converter prototype is designed and tested with peak efficiency of 98.9%.

Gallium nitride (GaN) devices are becoming more popular in power semiconductor converters. Due to the absence of the freewheeling substrate diode, the reverse conduction region is used in GaN transistors to conduct the freewheeling current. However, the voltage drop across the device in the reverse conduction mode is relatively high, causing additional power losses. These losses can be optimized by adequately adjusting the dead-time issued by the microcontroller. The dead-time loss minimization strategies presented in the literature have the common disadvantage that either additional hardware or specific converter data are needed for their proper operation. Therefore, this paper’s motivation is to present a novel dead-time loss minimization method for GaN-based high-frequency switching converters for electric drives that does not impose additional requirements on the hardware design phase and converter data acquisition. The method is based on optimizing the current controllers’ output with a simple perturb-and-observe tracker. The experimental results show that the proposed approach can minimize the dead-time losses over the whole drive’s operating range at the cost of only a moderate increase in software complexity.