Confirming PSU spec for steppers.

[EddyCurrent]

Following from Jonathan's post #99

Transformer Inrush - Open Electrical

[Jonathan]

Following from Jonathan's post #99

Transformer Inrush - Open Electrical

Good article, but they could have expressed the final equation more clearly to demonstrate their point. Also, it's a bit pointless to solve the differential equation using Laplace transforms when you can trivially separate the variables. This is how I did it:

From Faraday's law:
.
Seperate variables:
.
Use sin(A+B) identity to make it easy to integrate:
.
Integrate:
.
Use cos(A+B) identity to simplify:
. (1)
When the transformer is switched on, we have the initial condition relating to the residual flux:
.
So substitute this in to (1) to find constant, k:
.
So the solution is:
.

So now it's easier to see that the . term is a constant, which introduces a DC offset that disappears when the switching angle is . ... i.e at the peak voltage.

[EddyCurrent]

I used to like Laplace transforms but that was 40 years ago, I've never needed to use them since

[JAZZCNC]

I used to like Laplace transforms but that was 40 years ago, I've never needed to use them since

I much prefer the Lapdance performs. . Makes me constant, which introduces a DC offset that disappears when the switching angle is ...at the peak. .