Hi I am looking at the feasibility of driving BLDC motors (probably 4) from a 24v 150A alternator (around 3kw total) - the diesel motor driving the generator has a simple mechanical governor
My electronics knowledge is not strong and I am looking for guidance as to whether this is feasible. Can the VESC software / hardware really only run from a battery or can it be run directly (and or with a battery in the circuit) from an alternator
Because essentially there are two basic power "throttles" here - ie the diesel motor (governed notionally at a range of RPM) and the electronic speed controller - could they work together and would I need to somehow synchronize the diesel engine electronically with the power "demand" of the ESC - not sure if a capacitor bank could also help as a regulator.
So there are basically two issues are how to regulate the supply current to match that required by the speed controller to motors and I am also concerned that undercurrent / under voltage could damage the ESC control module as well.
In the very simplest implementation I would like to be able to only control the throttle to control the motor speed / output but can that been done or do I need to vary motor speed via the ESC?
Note I am not locked into an alternator I could also look at using a generator if this would simplify the overall control loop.
Thanks in advance for any assistance.
Simon
Curious if you found an answer? I am trying something similar, but using an engine to drive a BLDC with a battery in parallel. The energy needed for my application (drone) would come primarily from the BLDC in Regen mode, with battery bank used for backup power if engine fails, and surge power if needed by drone, so drone could land and have surge power for maneuvering. Haven't found a good way yet to limit Regen voltage so I don't fry batteries
Yes, you can. Provided that the alternator has a built-in rectifier (most do). You'd only have to worry about not exceeding the output current coming from the alternator, or ideally staying somewhat below the max output rating.
Let's say your alternator outputs solid 150A. You would want to configure your controller to allow up to 100-120A DC load, leaving some 30A as a safety buffer. In other words, you probably don't want to load all the way 150A.
A small battery would still make sense to have as a buffer and for reliability. Let's say your motor sputters and/or stops. No battery means your controller will shut down, likely, disgracefully. You also don't want to start the controllers directly from the alternator as there likely will be spikes and voltage will be unstable when the alternator starts. Battery is also good at absorbing voltage spikes, so they don't have to go to the controller only. Having the battery improves the reliability of your system and makes it behave more predictably in those situations.
Having a battery would also make your system more efficient as idling alternator (with the controller not doing the work) can be used to slowly charge the battery and not completely waste the energy from burning fuel. You want to size the battery for your specific application taking into account how it will be run, what duty cycles and load are expected. You'd want to se the regen current at max or below allowed charge current for the battery.
NextGen FOC High voltage 144v/34s, 30kw (https://vesc-project.com/node/1477)
My alternator is just a 7kw flipsky BLDC so no rectification. Ideally, I'd like to regulate the VESC Regen voltage to be the instantaneous battery voltage plus 1 volt, up to a maximum. I have a MOSFET circuit I have simulated which seems to do this, but haven't tested it yet
I have had success using a VESC as an Active Rectification tool
https://youtu.be/uZHcQC-RVZM
Here is my Discord where I have all of my projects
https://discord.gg/UVDqHn8c5C
Feel Free to message me on Discord, and I will share how I was able to setup the VESC to be a STABLE Active Rectifier. It does take some tuning with the Drive modes
Thanks, I have watched your videos in the past and am already on your discord. Very interesting stuff!