RE: esc selection help
td(on) Turn-On Delay Time ––– 59 ––– ns
tr Rise Time ––– 370 –––
td(off) Turn-Off Delay Time ––– 160 –––
tf Fall Time ––– 190 –––
First fet listed above
td(on) Turn-On Delay Time ––– 16 –––
tr Rise Time ––– 160 –––
td(off) Turn-Off Delay Time ––– 40 –––
tf Fall Time ––– 57
second fet from IR same amperage
the first one takes 427ns to turn on the second takes 176 ns. If the microcontroller is programmed to use the on and off time values of the above fet and you replace it with the second fet with very different on and off times the controller will be trying to turn on one fet while the one before it is still on and drawing current. 2 fets conducting at once will overheat the motor because you have both of those windings carrying current it shouldn`t be at that time. So software compatability is a major factor in the design of an esc. Basically all the controller is doing is turning fets on and off, it couldn,t care if less the fets should actually be turned on it's just doing what it's told to do. Change the values of the fet you have to change the software.
Both of those fets listed above will only sink that current at 10 V and 25 degrees C and dissipate a maximum of 330 watts. The numbers at 100 degrees are half that!
So how many do you want to run in series and parralel to get the voltage and power dissipation you actually think you'll get? Read the data sheets! they tell you all about the electrical characteristics of the part!
Take a look at a jeti spin 300 amp esc, it can handle 17700 watts, has about a 2" thick stack of fet boards and costs 657$
Not saying someone can't do this project from scratch, you just have to actually know what your talking about! Claiming you can just solder a bunch of fets on a 18 amp esc and have it work! LOL Maybe if you had the ability to re program the esc but I doubt they will give you the base code to modify. You can get a full hex dump from a controller then by hand convert it back to assembler......
These were just the first problems I saw when I checked the data sheets of high amperage fets.
Oh ya did I mention that the fets should be matched?
Oh ya the other thing not mentioned is the fact you need to use logic level gates, the are being controlled by a microcontroller putting out logic levels, The above fet von buddy there thinks will work are not logic level fets! You would have to build another circuit that takes logic level and boosts it to the proper voltage to allow the fet to turn on! Could do this with a couple small transistors, but you have now introduced more latency into the switching circuit.
To put it bluntly if it was easy and reliable Castle or any number of companies would have already put something out there that can take that kind of power, there is a market for it out there, do you not think they have people looking into this? Pay X$ and get an esc you can do anything too including arc welding!
As I posted above the only esc around that has these kind of numbers is 657$ and is huge!
Ignorance is bliss!
Still want to play? By the way I used to design microcontroller gate boards for medical lab equipment! I have a ton of experience setting up pwm for the conveyer drive systems. And code in 8052 assembler as well as PicMicro assembler, comes with the degree in computer sciences.
As I said these are just the glaring issues that hit me during my morning coffee. Couldn't be bother doing any more research into this, read 2 datasheets they gave me all the info I needed. You can argue with the numbers all you want they really don't care, they will do whatever they are supposed to do no matter how much you wish otherwise.
The number don't lie. This is not a simple pull this off and solder this on project.