bigmoose wrote:Njay, know that I am open to new stuff!! The AVR/PIC/Cygnal/etc. debate are sort of like the Ford/Chevy arguments of my youth. You tend to stick with the devil you know, rather than the "other" one.
But if you have a recommendation that is superior to the dsPIC30F3010-30I/SO I for one would be interested!
Njay wrote:By the way, is there a big difference between this thread's controller and this one's here?...
Lebowski wrote:Why did you choose the I/SO version (small outline, difficult to solder) ? I always go for the standard 0.1" pin distance DIP versions... I cannot solder SMD's or really small IC's
bigmoose wrote:First decide if it is PWM with over current limiting, where the throttle input sets the PWM period and you only abort on a blow up the FETs overcurrent; or true phase current control to terminate the PWM cycle, where the throttle sets a current threshold that will be met irregardless of the PWM period required to achieve it.
bigmoose wrote:Lots of good points being made!
That said, I would recommend that we not focus on all the bells and whistles and interfaces here at the start. No CAN bus, no logging, no fiber optic interface to a remote display. Start with the brute force core. Keep It Simple Stu... KISS!
First decide if it is PWM with over current limiting, where the throttle input sets the PWM period and you only abort on a blow up the FETs overcurrent; or true phase current control to terminate the PWM cycle, where the throttle sets a current threshold that will be met irregardless of the PWM period required to achieve it.
Then design the micro as bare bones as you can on one board, perhaps with the main power supply bus. Decide if this power supply bus is 24V, 15V or 12V.
Design the 1st round FET power stage, perhaps a 12 or 18 FET so it's relatively cheap when the smoke gets let out.
Rough design the ultimate FET power stage for the Collosus motor.
Design the driver stage to drive both, with the isolation power supplies. Now only component changes are needed for the lightweight FET power stage. The basic driver will drive both.
This is cumbersome and not optimum; but will give you "building blocks" for experimental development. When you have it working, you can add the cute user interfaces and roll it into two boards.
Lebowski wrote:I think you guys should start with something simple. Seeing as there's limited or no experience with the
PIC microcontroller... My first try was to make a LED go on / off based on a push button switch. Second
project was to connect the motor with 3 NMOS transistors (via drivers) to the PIC, force commutate with
speed control via the PIC's clock frequency (clock was coming from a variable frequency signal source).
Then I tried simple sensorless commutation by detecting ground supply crossing. Only then I added PMOS
(or high side NMOS) and PWM.
How much understanding do you guys have of how a motor works ? Are you at the level where you understand
that a (3-phase) motor is like a triangular wheel with 3 spokes ? A bit like a Wankel motor ? Rotating vectors ?
Do you know why 3 low-side NMOS transistors would be enough to run a motor in WYE config ? All this is
stuff you need to know...
I found taking baby steps a lot of fun as every evening I had something cool to try which had me hopping
on my seat with excitement (yey it works ). If you try to implement all your wishes in one go you'll
first spend 3 months coding followed by a big disappointment when you finally throw the switch and find
out it doesn't work.
Operating Supply Voltage 8V–60V
2.3A Sink and 1.7A Source Gate Drive Current Capability
Integrated Dual Shunt Current Amplifiers With Adjustable Gain and Offset
Integrated Buck Converter to Support up to 1.5A External Load
Independent Control of 3 or 6 PWM Inputs
Bootstrap Gate Driver With 100% Duty Cycle Support
Programmable Dead Time to Protect External FETs from Shoot Through
Slew Rate Control for EMI Reduction
Programmable Overcurrent Protection of External MOSFETs
Support Both 3.3V and 5V Digital Interface
Thermally Enhanced 56-Pin TSSOP Pad Down DCA Package
oldswamm wrote:The significance of the '2 grounds' column is that you can provide a separate return from the low side FET's source, right?
oldswamm wrote:Thank you.
That should give him something to think about. I'm worried he's going to get bored.
The significance of the '2 grounds' column is that you can provide a separate return from the low side FET's source, right?
bigmoose wrote:Arlo, with the IR2113S what I recommend you consider is driving one, two or perhaps three TO220/TO247 FETs directly. When you move to a FET/IGBT module we will put an emitter follower down stream of them to amplify current.
Keep in mind that IGBT drivers are sometimes a bit different. Some manufacturer brands need a -5 volt bias to get them turned off quickly/reliably.
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