Understanding the Continuity of Current in a Rotating Magnetic Field

AI Thread Summary
The discussion focuses on understanding the continuity of current in a rotating magnetic field, particularly between two points in the rotor magnetic field analysis. The net magnetomotive force (mmf) is calculated for specific current values, leading to a question about the behavior of the magnetic field between these points. It is clarified that if the currents are true sine waves, the magnetic field rotates smoothly, making the gap between poles magnetically invisible to the rotor. In contrast, a stepper motor with step currents would create a stepping magnetic field, allowing the rotor to be held between the poles. Continuous current is essential for maintaining a smooth and effective magnetic field rotation.
PhysicsTest
Messages
246
Reaction score
26
TL;DR Summary
Does the magnetic field rotate continuously or discrete.
I am analyzing the rotor magnetic field, i feel i understand the basic concept but have few clarifications.

1603550647150.png


At pt1, the net mmf due to currents
##i_a = i_{max}; i_b = -\frac{i_{max}} 2 ; i_c = -\frac{i_{max}} 2## is ##\frac {3F_{max}} 2##
1603550483841.png

Similarly i can do for Pt2. But my confusion is the region between the points pt1 and pt2, do i need to calculate similar to above. This question i am asking because if i see this website https://en.wikipedia.org/wiki/Rotating_magnetic_field ( i came to know from here) if share a screen shot from the website. The black arrow cannot stop in between the stator windings is my guess. Am I correct? What is the advantage of the continuous current in between pt1 and pt2?
1603550949200.png
 
Engineering news on Phys.org
PhysicsTest said:
The black arrow cannot stop in between the stator windings is my guess. Am I correct?
If the currents are true sine waves then the magnetic field will be rotating reasonably smoothly.

As the current through two pole windings are momentarily equal as they pass, the two poles will have the same magnetic flux so the gap between will be magnetically invisible to the rotor as it passes.

If it was a stepper motor, fed with step currents rather than sine waves, then the field will step and the rotor would be able to be held between the poles.
 
Very basic question. Consider a 3-terminal device with terminals say A,B,C. Kirchhoff Current Law (KCL) and Kirchhoff Voltage Law (KVL) establish two relationships between the 3 currents entering the terminals and the 3 terminal's voltage pairs respectively. So we have 2 equations in 6 unknowns. To proceed further we need two more (independent) equations in order to solve the circuit the 3-terminal device is connected to (basically one treats such a device as an unbalanced two-port...
suppose you have two capacitors with a 0.1 Farad value and 12 VDC rating. label these as A and B. label the terminals of each as 1 and 2. you also have a voltmeter with a 40 volt linear range for DC. you also have a 9 volt DC power supply fed by mains. you charge each capacitor to 9 volts with terminal 1 being - (negative) and terminal 2 being + (positive). you connect the voltmeter to terminal A2 and to terminal B1. does it read any voltage? can - of one capacitor discharge + of the...
Back
Top