self excite/reluctance actuator

Question 1

basic concept of a self excited actuator

Answer 1

a permeable material will move the area of highest magnetic flux. This maximises inductance and stored energy.

Question 2

uses

Answer 2

hydraulics, locks, relays

Question 3

when the core is drawn back into the coil how does I change

Answer 3

a small bump of increase then back down(all smooth)

Question 4

what happens to flux linkageat the saturtion of the iron

Answer 4

the flux linkage stops rising quickly with a rise in current

Question 5

Vb=

Answer 5

Vb=iR+dflux linkage/dt

Question 6

final state current

Answer 6

Iss=Vb/R

Question 7

stored energy

Answer 7

W=1/2LIss^2
L-constant
flux linkage=LI

Question 8

energy stored in the agnetic field

Answer 8

EfA=flux linkage*V/2R

Question 9

work done

Answer 9

=1/2I^2change in L

Question 10

flux

Answer 10

flux=NI/Sgap
Sgap=x/UoA
flux=NIuoA/x

Question 11

inductance of coil

Answer 11

L=flux linkage/I=N^2uoA/x

Question 12

force on the iron core

Answer 12

F=-I^2N^2uoA/2x^2

- indicating it is toward the centre of the actuator

Question 13

force and airgap relationship

Answer 13

as F-infinity
x- 0
limited by amgnetic saturation

Question 14

flux of air gap

Answer 14

Bg=flux /A

A- cross sectional area