Definition of co-energy
Definition of co-energy
(OP)
Related to my previous post - Can anyone tell me the meaning of the term co-energy, with respect to a magnetic system?
It vaguely rings a bell from my school physics many years ago, but I couldn't find a definition anywhere on the web. Even Wikipedia doesn't have an opinion, which is a first!
What I really want to know is the energy stored in my electromechanical actuator when current is flowing. I am modelling it in MagNet. Magnet gives 2 energy results - Magnetic energy and co-energy. These change when I simulate current flowing in the coil. They change by almost, but not exactly, the same amount. I suspect the difference is an artifact of the modelling, and actually they should change by the same amount.
Chris
It vaguely rings a bell from my school physics many years ago, but I couldn't find a definition anywhere on the web. Even Wikipedia doesn't have an opinion, which is a first!
What I really want to know is the energy stored in my electromechanical actuator when current is flowing. I am modelling it in MagNet. Magnet gives 2 energy results - Magnetic energy and co-energy. These change when I simulate current flowing in the coil. They change by almost, but not exactly, the same amount. I suspect the difference is an artifact of the modelling, and actually they should change by the same amount.
Chris
Talk To Other Members
RE: Definition of co-energy
Coenergy is defined as a convenience for computing force with current held constant.
F = -dW/dx with flux linkages held constant.
F = +dW'/dx with currents held constant
where W is energy and W' is coenergy.
W' = Sum(Lamdbak * Ik) - W
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Definition of co-energy
If you have a linear system, we have the surprising result:
F = + dW/dx (with currents held constant). Seems to violate conservation of energy at first glance.
But there is electrical input energy to consider
P = dWe/dt = i * v = i * dLambda/dt
dWe = i dLambda
If you hold current constant while changing x which changes L, then lambda must change (since lambda = L*i). That means energy is input from the elctrical system. The amount of energy input from the electrical system is exactly twice the energy output to the mechanical system in a linear electromagnetic system.
=====================================
Eng-tips forums: The best place on the web for engineering discussions.