Hi,
Currently designing a 28V PMSM motor drive (~300W) and would like to use the project to compare MOS to GaN FETs. My transistors are driven by an STDRIVE101 and have x2 competing MOSFETs packages. Does anyone have recommendations for the best way to adapt the STDRIVE101 circuit to drive you GaN FETs so that we can test these running at a higher PWM frequency and shorter deadtime? I do not wish to include a GaN specific driver(s) at this time.
Hello,
here are a few references that cover this topic in detail:
Selecting the Best GaN Gate Driver (epc-co.com)
Using GaN FETs with Controllers and Gate Drivers Designed for Silicon MOSFETs (epc-co.com)
A comment on this gate driver is that it seems the lowest operating voltage for the gate driver portion is 5.5V, when provided externally. This is quite close to the 6V max of the GaN FEts. If this supply is well controlled it will be OK, but on the high side a bootstrap supply using bootstrap diodes has notoriously bad regulation, especially when used with GaN FETs because of the over-charging during dead-time (the 3rd quadrant voltage drop of a GaN FET is quite a bit higher than a typical anti-parallel diode of a MOSFET). Even when using a zener diode and anti parallel Schottky didoe to control that max voltage, there can be high frequency ringing that could exceed 6V. I would recommend accurately measuring the high side gate very close to the GaN FET with a high bandwidth probe and scope ( Gallium Nitride Measurement Techniques | GaN First Time Right |EPC (epc-co.com))
For assessing GaN performance in motor drives, you could also use one of our reference designs which are fully tested and optimized:
GaN Motor Drives: Gallium Nitride-based Motor Drives | EPC (epc-co.com)
These are compatible with several digital controllers:
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Thanks Andrea, that’ most helpful. We will drop the the STDrive (or any of the STSpin) offerings and will instead start a new design with GaN optimised drivers.