- #36
SunnyBoyNY
- 63
- 0
Bararontok said:The source is a 1-phase AC source, not a DC source.
I assume you will rectify the single phase AC source to DC and put an energy buffer to the link as 1 phase connection is not capable of delivering continuous power as the three phases are.
Simply, if you motor takes 3 kW, then it is 3 kW continuous. Torque is dependent on the rotor/stator flux linkage and stator current. With sinusoidal windings the equations will look like this:
[itex]
Va = X*sin(ωt)\\
Vb = X*sin(ωt+\frac{2 Pi}{3})\\
Vc = X*sin(ωt-\frac{2 Pi}{3})\\
[/itex]
Current are:
[itex]
Ia = Y*sin(ωt)\\
Ib = Y*sin(ωt+\frac{2 Pi}{3})\\
Ic = Y*sin(ωt-\frac{2 Pi}{3})\\
[/itex]
Thus the power to the rotor is:
[itex]
Pr = Va*Ia+Vb*Ib+Vc*Ic = \frac{3}{2}XY
[/itex]
As you can see the rotor power is not dependent on phase.
On the other hand, provided that you want to pull power from a 1-phase connection with unity power factor, the available power is:
Pin = V*sin(wt)*I*sin(wt)=VI*sin^2(wt)=VI/2*(1-cos(2wt)).
Therefore you need an energy buffer.
I would strongly suggest you do some reading on the topic.
Excellent books are:
Principles of Power Electronics by Kassakian, Schlecht, Vergese from MIT
Fundamentals of Power Electronics by Erickson and Maksimovic from Colorado
Ac Electric Machines and Their Control by Torrey from Union