1st Order Nonlinear equation - Control

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SUMMARY

The discussion centers on solving the first order nonlinear equation y' = -(ay^2) + bx + c, which models the speed of an electrical motor during startup. The equation incorporates constants a, b, and c, with the initial condition y(0) = 0. While the user, Daniel, explored various methods including variable changes and substitutions, he found no success. Another participant confirmed that Maple can derive a closed form solution, albeit involving complex Airy functions, indicating that a straightforward substitution may not exist.

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danielgdls
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Hello everybody,


I've come cross the following first order nonlinear equation when trying to solve
for the speed of an electrical motor at any given time t during motor start.

y'=-(ay^2)+bx+c ; y(0)=0 ; a, b and c are constants; y=motor speed; x= time

The Motor Starter uses a linear Torque control and the load exhibits a quadratic
dependence of the motor speed. I am sure there is a possibility of solving this analitically.
I've tried changing variables, reduction and using substitution with no success. Maybe I
am missing something or haven't found the right substitution...Any ideas? I'll appreciate
any help on this.

Daniel.
 
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I plugged it into Maple, and there is indeed a closed form solution. But it's a complicated mess of Airy functions, so I don't think there's a "silver bullet" substitution that's going to make this nice for you.
 

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