[Objective] The self-excited synchronous motor (SESM) has a simple structure and low cost

utilizing both fundamental current and high-frequency sinusoidal current for excitation. However

the high-frequency current introduces higher-order harmonics

causing interaction between the stator and rotor magnetic fields. This generates radial electromagnetic forces

leading to motor vibration and deformation

and ultimately producing uncomfortable high-frequency electromagnetic noise. [Methods] To address the electromagnetic noise issue caused by high-frequency sinusoidal current excitation

a high-frequency square wave injection excitation strategy was proposed. The strategy utilized the low carrier ratio characteristic of square waves to elevate the injection frequency beyond the human auditory sensitive range (1~5 kHz)

effectively reducing noise impact. Firstly

the noise characteristics of high-frequency sinusoidal current were analyzed through power spectral density. Next

the square wave strategy was proposed and its response current spectrum was examined. Finally

the strategy was verified based on magnetomotive force theory and tested on a self-excited motor platform. [Results] The experimental results showed that

compared with the traditional excitation strategy

the proposed high-frequency square wave excitation strategy could reduce the power spectral density in the human auditory sensitive range by 51.86 dB/Hz while ensuring the same excitation effect

significantly mitigating the noise impact. [Conclusion] The proposed high-frequency square wave excitation strategy effectively reduces electromagnetic noise in the human auditory sensitive range

addressing the issue of excessive noise in traditional excitation strategies and providing a reliable low-noise control solution for SESM.