Another way to do motor current sensing for balance

Here is how they came out. This is from a replay of a lap at Donnington Park in a Lotus 49C, flat out. That’s why no footwork showing on the pedals. It a bit jerky but I was sitting in my sim to get the video. The clicking is my seat belt center latch I think. The sim itself is very quiet. It was pretty violent and full scale is 50 amps so this is around 5-10 amps on average with peaks getting close to 25 amps each way. Not bad. I had really thought currents would be higher.

Edit: A couple of points after more experience with the operation. The 100 Hz low pass filter is pretty lively but seeing it in action and looking close in slow motion, I’d bet it’s rounding off peaks to where it misses the max currents by possibly a fair amount. Some will be frame timing on my camera and some the low pass filter, but that it appears both segments are lit at times. That’s some fast polarity switching! I didn’t realize just how fast and extreme the motor currents would be changing. These meters were for me to be able to easily tell if my platform was in balance and they work great for that, but I’d guess peak currents are a fair bit higher than what these graphs are showing. Can’t really say how much higher though.

Anyone who builds these may even want to eliminate the R/C filter (short the R5 and R6 pads and don’t install C1 and C2) if you want more of the peaks, but the bar graph meters will have their own filtering and the data sheet doesn’t say how much. I’m pleased just the way they are but if I ever demount the boards, I think I’ll short out the filter to get even more response and better tracking of the peaks. Just don’t know how much better it will get. Probably not very much but who knows?

Anyway, see what you think.