Study on the Miniaturization of Transmitters Based on Bipolar Square Wave Inverter Circuits

The transmitter, as Controlled-Sourse Audio-frequency Magnetotelluric (CSAMT) system, has a direct impact on the accuracy and efficiency of the underground geological structure and resource detection. The traditional design adopts DC-DC boosting and multi-stage inverter topology to realize the transmitter voltage and frequency control, which has the problems of low voltage conversion efficiency (typical value <85%) and large volume and weight due to rectifier filter circuit, which limits the applicability of field exploration. In this paper, we propose a high-efficiency miniaturized transmitter based on a bipolar square wave inverter circuit, which directly inverts the AC square wave voltage output from the transformer, The proposed design eliminates the traditional rectifier-filtering stage, significantly reducing energy loss (simulated efficiency exceeding 90%) and volume (approximately 40% weight reduction) The power circuit adopts SiC-MOSFET to construct a full-bridge inverter and bipolar square-wave frequency divider circuit, and combines with a high-frequency transformer to realize voltage gain and frequency regulation. Verified by PSIM simulation and 15Ω load, the system can stably output 10kHz square wave signal with peak voltage of 150V, providing a lightweight and efficient solution for urban underground space detection with millimeter-level resolution.