EMF Generation

Question 1

example setup

Answer 1

A rotating rotor carries a magnetic field (airgap flux).

A stationary stator has two slots on opposite sides.

Each stator slot has
𝑁
𝑠
N
s
​
conductors (turns of wire), with length
𝑙
l (equal to the machine’s length).

Question 2

what happens when the rotor rotates

Answer 2

airgap flux (magnetic flux that crosses the airgap between the rotor and the stator) passes through the stator, as rotor turn anticlockwise, flux move relative to stator conductors, on left flux sweeps down on right up,

Question 3

how is emf induced

Answer 3

changing magnetic flux induces an emf in stator coil - faraday law

Question 4

what is the magnitude of the emf dependant on

Answer 4

ns, L, angulatr speed (speed = dtheata/dt) and how much flux density the conductors are experienceing

Question 5

how many types or emf are produced and why

Answer 5

conductors on left go down emf E1 has different polarity than right goes up E2

Question 6

if stators are connected at the end what os the potential difference between the 2 stator coils not on form sheet

Answer 6

𝑣𝑥𝑦 = 𝑒1 − 𝑒2

Question 7

assume airgap flux density is varying sinosoidally, what if formula for generated emf on left side e1 (form sheet)

Answer 7

𝑒1 =𝑁𝑠𝑙𝑟𝜔𝐵𝑚sin 𝜃 = 𝑁𝑠𝑙𝑟𝜔*sin 𝜔t
where r - mean radius and Bm = peak value of flux density

Question 8

peak generated emf and RMS val formula

Answer 8

E1hat = NS𝑙𝑟𝜔𝐵M
RMS val E1 = e1 hat / sqrt(2)
measured in V

Question 9

what determines emf

Answer 9

rotor speed, field strength BM and NS L r

so E1∝ω andE1∝Bm​

Question 10

is e2 = -e1

Answer 10

no