Other Parts Discussed in Thread: DRV8353
I have a condition where the phase current appears deformed or limited due to the over current fault from the Vds measurement by the DRV8301. I increased the Vds threshold incrementally to the maximum and the condition was still present. When the OC mode is disabled completely the condition was no longer present which allowed me to investigate further. I was able to observe an odd condition at the high side Vgs and at the resulting Vds. At essentially the same point in the phase current cycle I recorded high frequency ringing on the HS Vgs at turn on. I should note that it is visible on all three phases at the same time in the phase cycle for each phase, the images below are for phase C. I believe the ringing results in the FET not fully biased on which causes the Vds OC trip level to be exceeded. I have the gate current set to 250mA (DRV8301_PeakCurrent_0p25_A). The images below show the condition with each image further zoomed in (Vds OC is turned off). It doesn't seem to be a function of bus voltage or motor parameters, mainly phase current level. The high side measurements are made with differential probes and the FETs are TK100E06N1.
- Do you know what may be causing this high frequency ringing on Vgs?
- Are there other measurements you would like to see to help?