Evaluation of GaN transistor losses at MHz frequencies in soft switching converters

IEEE Trans. Power Electron.

Porter

et al. 2023

Gallium nitride (GaN) devices are revolutionarily advancing the efficiency, frequency, and form factor of power electronics. However, the material composition, architecture and physics of many GaN devices are significantly different from silicon and silicon carbide devices. These distinctions result in many unique stability, reliability and robustness issues facing GaN power devices. This paper reviews the current understanding of these issues, particularly those related to dynamic switching, and their impacts on system performance. Instead of delving into reliability physics, this paper intends to provide power electronics engineers the necessary information for deploying GaN devices in existing and emerging applications, as well as provide references for the qualification evaluations of GaN power devices. The issues covered in this paper include the dynamic instability of device parameters (e.g., on-resistance, threshold voltage, output capacitance), the device robustness in avalanche, overvoltage and short-circuit conditions, the device's switching reliability and lifetime, as well as the device's ruggedness under radiation and extreme (cryogenic and elevated) temperatures. Knowledge gaps and immediate research opportunities in the relevant fields are also discussed. 1

Section: Characterization Methods and Resultsmentioning

confidence: 99%

Stability, Reliability, and Robustness of GaN Power Devices: A Review

Kozak

IEEE Trans. Power Electron.

Porter

et al. 2023

“…It has been found [13,14,24] that for many commercial GaN switches operating at hundreds of volts and MHz frequencies, the dc conduction resistance should be scaled by a factor, yielding an appropriate value for dynamic that may be 3-6 times the dc room temperature on-state resistance value. It is also known that at sufficiently high frequencies, output capacitance loss of GaN switches may be important even under ZVS operating conditions [25,26], but for our operating conditions (up to few MHz operation) it is believed that dynamic is the dominant loss concern [24].…”

Section: A Switch Lossmentioning

confidence: 96%

An optimization approach for high-efficiency high-power-density boost converters

2018 IEEE 19th Workshop on Control and Modeling for Power Electronics (COMPEL)

Perreault

2018

Boost converters running in valley switching mode have the advantages of low switching loss and small inductor size. However, the switching frequency is not fixed as operating conditions vary, which can make inductor design for this converter challenging. In this paper, a systematic optimization approach is presented that is suitable for wide-input-voltage range designs such as power factor correction (PFC) converters. The loss of each component is modeled as a function of the operating point, and the efficiency is estimated over the entire input voltage range. Given a set of selected cores and Litz wire, an optimal inductor design can be found on a plot of efficiencies and air-gap lengths. Genetic algorithms can be used to find the optimal design with customizable cores. Experiments are conducted to verify the model and the approach. One of the prototypes, designed as the first stage for an ac-dc converter system, achieves around 98% efficiency over the input range of 70V to 170V, boosting to 363V at 45W. The prototype converter has a total volume of 2.8cm 3 and reaches a power density of 263W/in 3 .

“…Resonant gating techniques can reduce the driving losses [31]- [33]. Under certain voltage and frequency conditions, the resonant charging/discharging process of the switching device's junction capacitor C oss could generate significant power losses [34]- [36].…”

Section: Comparison Of Zvs Resonant Invertersmentioning

confidence: 99%

Push–Pull Class $\Phi _{\text{2}}$ RF Power Amplifier

Zulauf

IEEE Trans. Power Electron.

et al. 2020

The Class Φ 2 /EF 2 amplifier is an attractive topology for high-voltage and high-frequency power conversion because of the high efficiency, reduced device voltage stress, simplicity of gate driving, and load-independent ZVS operation. Due to many degrees of freedom for tuning, previous studies can only solve the single-ended Φ 2 circuit using numerical methods. This work focuses on improving the design and operating characteristics of a push-pull Φ 2 amplifier with a T network connected between the switch nodes, or a PPT Φ 2 amplifier. The PPT Φ 2 amplifier has less circulating energy and achieves higher cutoff frequency f T than other Φ 2 /EF 2 circuits. We, then, present a series-stacked input configuration to reduce the switch voltage stress and improve the efficiency and power density. A compact 6.78-MHz, 100-V, 300-W prototype converter is demonstrated that uses low-cost Si devices and achieves 96% peak total efficiency and maintains above 94.5% drain efficiency across a wide range of voltage and power. Together with the advances in wide-bandgap semiconductors and magnetic materials, the PPT Φ 2 circuit opens more possibilities for the state-of-the-art performance of solid-state RF amplifiers in high-frequency, high-power applications, including wireless charging for electric vehicles, plasma RF drives, and nuclear magnetic resonance spectroscopy.