A Method for Time-Frequency-Domain Electromagnetic Transmitting Waveforms Synthesis Based on Particle Swarm Optimization

In the field of electromagnetic transmitting for geological exploration, PWM waves containing multiple harmonics are often output from an inverter bridge to the ground or ocean. Currently, Time-Frequency-Domain electromagnetic (TFEM) is a novel detection technique. This paper utilizes Particle Swarm Optimization (PSO) to compute the output waveform with energy concentrated in specific harmonics, and a controller is used to control the inverter bridge output the time-frequency-domain electromagnetic waveform. The main steps include performing a Fourier expansion of the designed time-frequency-domain waveform, setting an objective function, and optimizing it using PSO to find the optimal switching angles. The time-frequency-domain waveform calculated by PSO enables amplitude-equal output of specific harmonics, improving detection efficiency and reducing the time for exploration in fieldwork.