High-Power Excitation System for Electromagnetic Acoustic Transducers Based on Direct Digital Synthesis

Electromagnetic Acoustic Transducer (EMAT) technology enables non-contact and high-temperature-tolerant inspection of oil pipelines, but conventional excitation circuits often suffer from waveform distortion and insufficient output power, which limit the engineering application effect of this technology. To address these issues, this paper presents a high-power EMAT excitation system based on Direct Digital Synthesis (DDS) with a field-programmable gate array (FPGA) as the core controller. The system generates programmable waveforms and drives a two-stage power amplifier to achieve high-voltage, wide-band excitation. Circuit simulation and experimental results demonstrate an output of over 1200 Vpp, an output power of over 5000 W, and an excitation frequency of 4 MHz. Thickness measurements on steel samples (4.9-13.7 ~mm) achieve <1 ~mm error, and volumetric defects (6 ~mm depth) are accurately identified. The system stably outputs clear echo waveforms, meeting engineering requirements for pipeline inspection. This research provides strong support and technical reference for the engineering application of high-performance EMAT pipeline detection systems.