VESC 75/300 as generator inverter troubleshooting

Hello everyone !

I’m currently working on retrieving the energy from a low speed high KV generator. I’ve bought a Vesc 75/300 for that but I’m having troubles getting it going. Here are the specs:

• KV = 0,36 RPM/V
• 10 poles pairs
• Working Speed: 10-20 RPM
• Construction: axial flux ironless stator sensorless
• Currently hooked up to a 48V 100Ah lead acid battery pack through a 15A fuse

Here’s what I’ve done at first:

•  Setup all the required tension/current settings and max erpm to 200 in sensorless FOC and openloop limit at 20 ERPM
• Done a FOC setting sensing, R and L without issues, Lambda on second try with those settings: I = 3A ; D = 0,3 ; omega = 40 ERPM/s and getting : lambda = 100mWb and observer gain = 0,1.
• With those values the generator wasn’t turning when imputing a 3 A value in VESC tool, just oscillating between two poles.
• I’ve redone several times the FOC detection for checking if values where consistent and I noticed that lambda and the observer gain never changed from there originals values like it was maxed out.
• According to Benjamin’s equations for approximating those values from KV (seen in another post) I’m getting : lambda = 60/(SQRT(3)*20*PI()*0,3456)= 1595 mWb and observer gain = 1000/(1595²)=0,00039
• From that i upped the values to respectively 1000mWb and 0,01 for the observer gain wich is the lowest we can set in vesc tool.
• Now the generator seemed to turn at least a few steps before cogging between to pole
• I then set the sample in V0 and V7 to true and get the generator start turning rather smoothly at 10 RPM
• At that point I hooked up a small motor to turn the generator shaft and start to test regen braking. With 0,1 then 0,2 and 0,3 I got to slow down the motor a bit proportionally to the regen amp (dutty were between 70 and 80%) but it would cog and not slow it down smoothly, the amp to battery was jumping between 0 and the value of the regen value.
• After a vesc restart I was not able to get it to turn in motoring mode with the same settings.
• At that point I tried through the wizard an autodetect of a small outrunner (200G outrunner selected in the wizard) to check if the vesc was working right, it tried a few time before actually achieving to turn it during detection. When it finished the sensing, I got a test result showing: “test successful, test amp: 400A” and at the same time the motor start smoking so I unplugged the vesc.

What could have gone wrong with this setup wizard?

Since then I have re-plug it to the generator and redone a foc sensing, R and L measurement worked okay but the flux linkage measurement only does a small ticking noise and is unable to get result (same parameters as before). When plugging the same parameters as before and trying to spin it with 3A a small ticking noise appears but no more oscillating between two poles. In realtime data tab FAULT CODE stay at 0.

Does someone have a thought of what could have went wrong? Could have the vesc been damaged? (I'll post my parameters screens below)

Thanks in advance for everyone willing to help !