We use the relation:
 |
For the fundamental component 
of 
, we obtain:
 |
For the 3rd rank harmonics of , we obtain:
 |
The 3rd rank harmonics of 
, 
, 
being in phase, they form a homopolar system which is being elimineted from the voltage .
And so on.
Remark.
We can obviously start directly from the voltage to obtain its development in Fourier series.
