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Old 10-21-2015, 03:16 PM   #2212 (permalink)
thingstodo
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Quote:
Originally Posted by e*clipse View Post
For detail, I've added resistance in the battery pack, resistance and inductance in the power wires to the controller, resistance in the bus capacitor, resistance and inductance in the motor controller bus, and resistance and inductance in the motor load. The motor is wired as a wye connection with two inputs (with ideal switches) and one output with a pair of diodes returning to the input phases. **whew**
I split this into a couple of posts - BOY DO I GET LONG-WINDED!

Would it simplify things a bit to model as 2 separate systems?

I put an X beside the parts that I think can be ignored for simplicity. The resistances and inductances should be really small?

Ideal Battery -> series resistance ->
ideal wire series resistance -> Xseries inductance ->
ideal capacitor series resistance -> parallel capacitance ->
ideal wire Xseries resistance -> Xseries inductance ->
Ideal battery

Set up the peak to peak or ripple voltage that is acceptable and find out the capacitance required if you 'take all of that energy out of the capacitor' as a step change

Then the second circuit is a bit simpler

Ideal capacitor -> series resistance ->
ideal wire series resistance -> Xseries inductance ->
ideal motor series resistance -> series inductance ->
ideal wire series resistance -> Xseries inductance ->
Ideal capacitor

The same peak to peak or ripple voltage (I think a triangular wave source added to the ideal capacitor may have worked ... this was 25 years ago in university so I'm a bit fuzzy) on the capacitor should illustrate the differences in the controller side as the ripple voltage is higher or lower.

In my uninformed opinion (OK - guess!), the worst case for capacitance should be when the triangular wave is at it's minimum (from the battery source) and the controller still needs to send a maximum duty cycle pulse to the motor?
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e*clipse (10-21-2015)