Resonance Suppression and EMI Reduction of GaN-Based Motor Drive with Sine Wave Filter

Applying high-frequency power devices, such as gallium nitride (GaN) semiconductor devices, to the motor drive can significantly reduce system volume, losses, audible noise, and increase system power density. In this article, an LC filter designed as a sine wave filter is introduced into the servo drive system based on the GaN power device. An undamped method with variable delay time is proposed to solve the electrical resonance issue caused by the LC filter and stator inductor. Detailed stability analysis is conducted, and rules on parameter tuning are provided. With additional proper time delay, the system can be stable without any extra sensors or power losses. Besides, this method is suitable for resonance suppression at a variable switching frequency. Moreover, a wait-free and phase-continuous spread spectrum frequency modulation is applied to solve the issue of electromagnetic interference (EMI). The field-programmable gate array is used to achieve high control bandwidth when implementing the control algorithm. Finally, the ideal sinusoidal drive and low conducted EMI of a permanent magnet synchronous motor is realized. Experiments on a 100 kHz GaN inverter with the LC filter verify the validity of the proposed design and method.