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help on starting a project on BLDC

Hello every body I told to start up a project on BLDC motor postion control system this would be my first project based on motor control,can any body please guide me in some aspects which are needed to start the project ,I have browsed through the net and downloaded few of the documents on BLDC motor makes ,few on PID implementations . My design should be based on CAN and Devicenet protocols . the Motor should be 3-4amps 24v . the thong which is stopping me is where to start and what to start i cant run into it blindly with out a proper direction . so i am looking into this group to give me a start up idea of designing it and embedding code into it

the aspects are what encoder shall be selected for the protoboard shall be cheap and easy to work on do i need the tachometer or just counting the encoder reply will do and any suggestion on your own which help me to execute this task

thanks & regards PMM

Reply to
pmm
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I am adding one more

how to test the algorithms is there any demonstration board existing ,can one provide me the name of it and the provider

Reply to
pmm

Hello Mr Paul Thanks for your reply , I was reading thru the PIDs questions posts in the forum,and I feel like its pretty tough to implement them , how do I test them, is there any demonstration tool ready so that I can get one to test them. any ideas from your side on those algos , will help me a lot

thanks and regards PMM

Reply to
pmm

Good start. The BLDC motor is just like a brushed motor except it lacks the mechanical switch to do the commutation- you get a set of rotor position feedback optos so you can do it electronically. Google for 'brushless motor controller' and you should find a bunch of devices to make this easy. They'll also have design examples with them.

The hardest bit in hardware will be making an output stage that doesn't go pop too easily.

That depends on how much control you want. The motor feedback is coarse, just a few changes per rev, so speed control can be expected to be lumpy, and position control coggy. smooth and/ or good positioning, and you'll need an encoder with appropriate resolution - NOT a tacho for position control.

Paul Burke

Reply to
Paul Burke

PIDs are really easy to implement, it's the tuning that's hard! But a lot depends on your hardware/ software setup. With a really fast processor, and plenty of resolution on the DAC (or PWM or whatever)things get easier.

Proportional? Subtract position from setpoint. Multiply by gain. Output to DAC.

Integral? Calculate error as above. Add to integrator Don't let it overflow so keep it within a settable limit (both ways). Multiply by integral gain. Add to P and output.

Derivative? Subtract last error from current error. Multiply by D gain. Add to the others and output.

Think about the resolution required- typically you will be talking about

16 or 32 bit bit setpoints and feedback, 16 bit error, 32 bit integrator and 16 bit gains. It's useful to have some idea what gain range and resolution you will be using- so you can shift the multiplied results appropriately.

The best demonstration tool is a motor, encoder, amplifier and processor!

Paul Burke

Reply to
Paul Burke

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