Efficiency Comparison Between Si-IGBT-Based Drive and GaN-Based Drive

High motor efficiency, lower torque ripple, close to ideal sinusoidal motor current waveform, smaller filter size, etc. are a few of the advantages of using high-frequency pulsewidth modulaton (PWM) (in the range of 50 to 100 kHz) in motor drive applications. However, higher frequency PWM is also associated with voltage reflection and motor insulation breakdown issues. Due to high losses, Si IGBT-based inverters cannot be operated at high switching frequency. Work on SiC and GaN-based inverter has progressed and variable-frequency drives (VFDs) can now be operated efficiently at carrier frequencies in the 50 to 200 kHz range, using these devices because of extremely low turn-on and turn-off losses. At high frequency, physical and electrical rating of output filter reduces, thereby improving efficiency. Loss in ac motors also reduces because of sinusoidal waveform. All the above features put together improves system efficiency. This paper focuses on comparing the efficiency of Si-IGBT-based drive with a 6-in-1 GaN module-based drive, which is operating at a carrier frequency of 100 kHz with an output sine wave filter. Experimental results show the GaN-based drive has a better system efficiency compared to the standard Si IGBT-based drive.