Impact of non-ideal waveforms on GaN power FET in magnetic resonant wireless power transfer system

Abstract

GaN field-effect transistors (FET) have low conduction and switching losses in high-frequency (>MHz) resonant wireless power transfer systems. Nevertheless, such systems impose a unique stress on GaN FETs owing to their non-ideal voltage waveforms. In this work, we report the observed non-ideal behavior in a 6.78 MHz magnetic resonant wireless transfer system that employs class-D GaN power amplifiers. The non-ideal waveform phenomenon existing at the output of the power amplifier is explained. The study analyzes the causes of this phenomenon, including the coupling coefficient k of the coil, the DC input voltage of the amplifier, and the load on the receiver. Each parameter is simulated and analyzed using LTspice. The influence of the phenomenon on the on-state resistance of the GaN device is proved in an experimental measurement, and the cause of the phenomenon is explained.The study combines a theoretical simulation and an experimental test to discuss the effect of this phenomenon on GaN power devices and proposes the corresponding solutions, which include the limitation of voltage, current, and power of the system, thermal management, and other protection measures.

Mechanism of wireless power transfer system waveform distortion caused by nonideal gallium nitride transistor characteristics

“…The waveform distortion has been reported in Ref. [15]. To ensure an accurate R on , we selected the average value of the middle part (in the box) as the result in Fig.…”

Design Consideration of Bidirectional Wireless Power Transfer and Full-Duplex Communication System via a Shared Inductive Channel

“…The range of φ is [0, 2π]. Therefore, Equation (9) shows that the direction of the output power is determined by φ. The magnitude of the transmission power is affected by the phase shift angles α, β, and φ.…”

“…Based on convenience and safety, wireless power transfer (WPT) technology has been developed rapidly in the field of electric vehicles [1][2][3], urban rail transit [4], motor control [5,6], LED [7], and so on. Along with the development and optimization of new devices [8,9], topology and coil structure [10,11], the performance of WPT system has greatly improved.…”

Bidirectional Simultaneous Wireless Information and Power Transfer via Sharing Inductive Link and Single Switch in the Secondary Side

“…Besides, it is also popularly applied in the smart house, equipment underwater and other applications [9][10]. The performance of WPT system has also been optimized by changing the coil shape and number [11], using novel switching devices [12][13], and enhancing the inductive coupling characteristics [14]. Several WPT standards have been set to increase the interoperability of different devices.…”