Other Parts Discussed in Thread: DRV8302
Hi,
The current shunt is 1mohm and the peak current is 125A. I found, when the max duty is 91% set by MCU, the current amplifier output (SO1) distorts at positive peak (as Channel 3 shows). All the tree phases have this issue.Meanwhile, the negative peak is always fine. The actual Phase A current is measured by current probe in Channel 4, no obvious distortion happens.
When the max duty is set as 80%, the SO1 distortion disappears (as Channel 1 shows).
At postive peak, the high side FET is at its max duty, so I checked the gate drive. Channel 2 is the high-side drive, Channel 3 is the low-side drive, Channel 1 is SO1. The gate drive resistors are 0 ohm, sink and source current (Idrive) are set as max level. No abnormal gate drive is found.
I also check the current amplifer. The CL is 270pF. I think it is not the slew rate issue.
The positive peak of SO1 is below 2.5V (offset is 1.65V for 0A), so it is not the amplifier output maximum limit issue.
I would like to know why positive peak of SO1 distorts when max duty is set as 91%. Any other measurement I could do for this issue?
Thanks.