Optimization of SHMPWM emission strategy for fine electromagnetic detection in the frequency domain

Abstract In frequency-domain electromagnetic detection, the resistive-inductive characteristics of the ground and cables, along with dead-time effects, distort the rectangular emission current waveform. This distortion gives rise to sideband interference and results in the loss of main spectral energy, ultimately compromising detection effectiveness. To achieve energy focusing and precise allocation, a bipolar-optimized selective harmonic mitigation pulse width modulation (SHMPWM) strategy considering inductive loads is proposed. This strategy analyzes the impact of inductive load effects on the waveform and extends the waveform based on the equal-area principle, culminating in a compensation method to ensure that the optimized emission energy aligns with the ideal value. To enable customized spectrum and precise compensation, a particle swarm optimization (PSO) algorithm based on an adaptive velocity formula is designed to solve the nonlinear equations of SHMPWM, accurately yielding switching angles and thereby enhancing harmonic control. Experimental results validate the effectiveness and superiority of this strategy.