A Low-Profile GaN-Based Integrated Motor Drive for 48V FOC Applications

A GaN-based motor drive for permanent magnet synchronous motors (PMSM) was designed and experimentally evaluated with a high-speed outrunner motor at 48 V. Leveraging the benefits of gallium nitride (GaN), the motor drive is optimized for high efficiency and high power density with an ultra-low profile, designed to integrate with 48 V motors. The switching frequency of 100 kHz in combination with field-orientated control (FOC) reduces the current ripple versus conventional block-commutation. Lower current ripple improves motor efficiency while reducing the dc link capacitance, which results in an overall improvement in the system’s power density and efficiency. This paper also investigates the relationship between GaN HEMT switching speed and voltage slew rates experienced by the motor. The experimental prototype was validated to improve the system efficiency over 5% by switching at 100 kHz rather than 20 kHz, without any significant impact on the power loss or temperature of the GaN HEMTs.