Mega-Hertz High-Voltage EMAT Pulser Based on LCC Resonant Inverter Using SiC MOSFETs

Pulse power supply is an important field of high-frequency power electronics. In advanced applications, such as ultrasonic sensors, Lidar waves, and laser generators, the voltage supply with high amplitude and high frequency is required to achieve sufficient technical performance. Meanwhile, the high power quality is pursued in some sensor applications to obtain better performance. This article develops a ±1000-V/1.5-MHz LCC resonant pulse inverter for electromagnetic acoustic transducer. First, the LCC filter is optimized to achieve the goals of low total harmonics distortion (THD), small gain variation, and zero-voltage soft-switching (ZVS) in a wide load range. The design guideline of LCC filter for nonresistive load conditions is proposed, and the design considerations for burst mode converters are summarized. Second, the startup and ending transients occur repetitively, which is a common problem for burst mode converters. The proposed precharging and damping strategy solves this transient problem. Moreover, by analyzing the circuit state equations, this strategy provides a general method for eliminating transients of resonant converters. Next, the signal receiving circuit uses depletion mode MOSFETs to attenuate the high transmitting load voltage while amplifying microvolt receiving signals. Finally, the experimental results under four worst case conditions validate the LCC filter design. A control experiment with or without the proposed transient mitigation method has been conducted to verify the effectiveness of the proposed strategy.