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A gallium nitride (GaN)-based resonant step-up converter is proposed for the application in the satellite electric propulsion (EP) system. This converter consists of a full-bridge inverter, a resonant tank and a multi-stage Cockcroft-Walton (CW) voltage multiplier to provide a high gain. Additionally, the air-core transformer is introduced due to the megahertz switching frequency allowed by the GaN device. Thus, the limited magnetizing inductance of transformer and the remarkable junction capacitance of diode have to be carefully considered in the resonant tank design, especially after considering that this converter normally operates at the light load in the EP system. In this work, the 4-order LCLC resonant converter is investigated. The recommended parameter selection for the 4-order resonant tank is also provided. A 1.2-MHz, 23-V/2.5-kV, and 6-W prototype is demonstrated. It achieves a low harmonics distortion and a low power loss with the zero voltage switching (ZVS).

Gallium nitride (GaN) high electron mobility transistor (HEMT) is a promising candidate for the high-density power converter applications. Due to the low switching loss, the GaN HEMT may lead to a new horizon in the applications, such as fast charger, wireless charging, and 5G power amplifier. However, the fast switching speed of GaN HEMT makes it extremely sensitive to parasitic parameters, especially for the low-voltage GaN devices with small packages. Conventional switching loss estimation methods, which are normally based on the calibration fixture or modification of test circuit, cannot be effectively utilized for GaN HEMT. This article presents an accurate switching loss estimation method using the postprocessing technique. The proposed switching loss technique consists of three parts of signal processing, which are the wavelet denoising process to minimize the influence of background noise, the voltage–current ( $ V-I$ ) alignment process to reduce errors from probe propagation delay, and the linear interpolation process for further improvement of alignment accuracy. In addition, a modified SPICE model is proposed to investigate the influence of parasitic parameters on switching losses by the circuit simulation. Based on the theoretical switching characteristics, the switching loss estimation method is finally validated experimentally on a commercial 40-V/10-A GaN HEMT in a double-pulse test.

The step-up resonant converter serves as an essential part of the ion propulsion power suppy (IPPS), which has been widely used in micro- and nano-satellites. However, the common-mode (CM) noise could deteriorate the converter performance, and hence it needs to be evaluated and mitigated. This work studies the CM noise of a 2 W, 500 kHz, 15-V/1.2-kV Gallium Nitride (GaN) based LCLC resonant converter. Based on the working principle of this converter, the CM noise current path is analyzed. In addition, an LCL filter is applied to evaluate its performance for CM noise suppression. The experimental and simulation results show that significant CM noise exists in the GaN-based step-up LCLC resonant converter from the frequency range of 150 kHz to 30 MHz, and the LCL filter realizes a good suppression for the CM noise.

GaN HEMT is a promising alternative of Si MOS-FET for the high-density power converter applications. Due to their lower switching losses, GaN HEMT may lead to new horizons in the application area of power electronics such as faster charger, wireless charging, and 5G power amplifier. However, evaluation of power loss and EMI of GaN HEMT versus Si MOSFET for the application in a synchronous low-voltage buck converter have not been comprehensively investigated. In this paper, the application boundary of 40-V, 10-A GaN HEMT is analyzed by comparing with Si counterpart has been assessed in terms of power loss, oscillation and EMI though the double pulse test. Based on the DPT results, it can be found that the switching energy of GaN HEMT is nearly 1/10 of Si MOSFET and also exhibits zero reverse recovery loss. Additionally, the impact of different switches on the converter performances is analyzed by the PLECS thermal simulation. It can be found that GaN-based converter shows lower efficiency at low frequency, and its efficiency is more seriously influenced by the dead time which is its application boundary.

Gallium nitride (GaN) high electron mobility transistor (HEMT) is a promising candidate for the high-efficiency and high-frequency motor drive applications when compared with the silicon (Si) counterpart. In this work, the GaN-based and Si-based devices based full bridge converters for DC motor drive are investigated and compared. Firstly, three different driving schemes including bipolar, unipolar and synchronous rectification are analyzed. Then, performance comparison between 40-V/l0-A GaN HEMT and Si MOSFET are conducted based on the datasheet and double pulse test experiment results. Finally, the model of DC motor drive is proposed based on PLECS thermal simulation. Based on the model, the impact of three schemes and two different switches on the efficiency is investigated. Results show the GaN-based full-bridge converter has higher efficiency and lower power loss.