Hi everyone,
I recently purchased some VESC 75V 300A units and trying to use those to replace Kelly KLS7245N controllers which are rated at 350A. The motor is Motenergy ME0907.
Considering the functionality, especially software-wise VESC is certainly miles ahead of Kelly, kudos to Benjamin for the fantastic work! However I met one problem I can't seem to solve, which is controller shutting off the operation when the absolute current exceeds the limit. The limit is now set at 480A, which is the maximum that the software allows. However VESC terminal reports ABS currents higher than 500A once in a while and shuts down the motor. This normally happens when I try to apply a lot of throttle right at take off. Kelly doesn't have this problem. My question - would it be possible to configure the controller so it limits the motor current as opposed to stopping the motor? Thanks
The max value is there to protect the Unit. So you should not go higher! You should enable RT-data in the right menu and go into Data Analysis >> Realtimer Data. Locate the FOC Tab.
Now you can see the currents and you will probably notice that the currents shoot up quickly when you apply throttle and you might see current ripples. If the motor is well tuned, the spickes and ripples will go away. You can try and navigate to Motor Settings FOC in the left menu and change T in the lower section. instead of 1000uS use 500 or even 250uS and press CALC Apply Old. Then write the motor configuration and try again, watching the RT-Data FOC currents. Start with little Motor Current max values and observe if you can see ripple when going up in power. Work yourself up in power. Some motors tend to run better with 250uS and the current spikes flatten a lot.
Thanks for fast response Frank, I'll try that. However this motor inherently will produce higher currents once in a while, so I was wondering isn't there any option to top at the current limit rather than stopping the motor? Kelly controller apparently works in that manner, as it doesn't stop the motor in such situation, but instead just spins it as much as it can at its maximum capacity. Hope this makes sense.
If you get spikes that high, you will burn the VESC 75/300 with such spikes. This value is there to protect the unit. You better tweak the motor parameters, Looks like this motor is similar to the golden motor 5KW. Adjusting T to 250uS and using the latest VESC-Tool improves the performance drastically. We use the Wizard and then manually adjsut T and recalculate and the write this config. This brings down all spikes and makes the motor a lot more responsive.
I fixed this by increasing the position and negative ramping time at PPM settings. Now the peak currents are much lower when I throttle. Thanks for your help!
General > Current > Motor Current Max and Motor Current Max Brake do exactly what you are talking about. They act as a soft limit to current which will not trigger a fault.
However, current still tends to overshoot these soft limits from time to time, especially if motor parameters are not well tuned. Sometimes this will get all the way up to Absolute Maximum Current and trigger a fault. Set these soft limits only as high as necessary. If they are too close to Absolute Maximum Current then faults will happen often.
Adding a throttle ramp as you have done is a great idea! Also consider configuring the duration of your Fault Stop Time. I drop it down to 100mS always, and tend to disable Safe Start so controls come right back after the fault. This way I can still tell something went wrong, but wont lose braking long enough to crash into a parked vehicle.