- •Advanced chapters of theoretical electroengineering.
- •Inductance of the two-wire transmission line per unit length
- •External fluxes
- •Total inductance
- •Forces. The first line.
- •Forces. The second line.
- •Solution of the Laplace’s equation by separation of variables.
- •Properties of the Laplace’s equation.
- •Choice of a coordinate system
- •Variable separation in cylindrical coordinates
- •Angular function
- •Radial function
- •General solution of the Laplace’s equation in a cylindrical coordinate system
- •Application of the variable separation method for the magnetic field modeling
- •Reduced scalar magnetic potential
- •Combination of scalar magnetic potential and the reduced magnetic potential
- •Combination of scalar magnetic potential and reduced magnetic potential
- •Combination of scalar magnetic potential and reduced magnetic potential
- •Magnetic field of the line current near a magnetized cylinder
- •The scalar potential induced by the current line
- •The current potential in the cylindrical coordinate system
- •The current potential in the complex plane
- •Expansion of the current potential in the cylindrical coordinate system
- •Potentials in the problem domain
- •Magnetic field intensity in the problem domain
- •Magnetic field intensity induced by the wire with the current
- •Definition of coefficients
- •Solution of the problem
- •Magnetic field directions
- •Inductance of the two-wire transmission line per unit length
- •The flux induced by the magnetized cylinder
The current potential in the cylindrical coordinate system
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r sin( ) R sin( )
b r cos( ) R cos( ) |
r cos( ) b R cos( ) |
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R sin( ) |
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tg( ) |
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arctg |
R sin( ) |
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b R cos( ) |
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b R cos( ) |
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The current potential in the complex plane
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ln Q ln Q e |
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ln Q ln Q j |
Im ln(Q) |
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Q P b |
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Im ln(R e j
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z x jy |
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b) Im ln |
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Let us introduce a parameter:
t Rb 1
Im ln b Im ln 1 t e j
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Expansion of the current potential in the cylindrical coordinate system
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z x jz |
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Im ln b |
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xk |
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ln 1 |
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k 1 |
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b x
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ln 1 te j t |
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sin k |
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e jk |
cos k j sin k |
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Im e jk sin k |
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sin k |
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k 1 |
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k 1 k1 tk sin |
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Potentials in the problem domain
Inside the cylinder. |
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sin(k ) |
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(1) |
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General case. |
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gk |
cos(k ) hk |
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k 1 |
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Case of the line current source |
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U r, ck rk sin(k ) |
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(potential on the x-axis = 0): |
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k 1 |
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Outside the cylinder. |
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sin(k ) |
Um |
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General case. |
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k 1 |
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Case of the line current source: |
Um r, dk r k sin(k ) |
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k 1 |
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Current potential on the |
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surface of the cylinder. |
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k 1 |
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ck hk(1)
dk hk(2)
t Rb
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Magnetic field intensity in the problem domain
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Hr r, |
U r, |
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Inside the cylinder. |
kck rk 1 sin(k ) |
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H r, |
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U r, |
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kck rk 1 cos(k ) |
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k 1 |
Outside the cylinder. |
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Um r, |
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Hm r |
kdk r k 1 sin(k ) |
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Hm |
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1 Um r, |
kdk r k 1 cos(k ) |
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k 1 |
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Magnetic field intensity induced by the wire with the current
Radial component of the |
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Uc R, |
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Hc r |
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tk sin(k ) |
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field intensity induced by |
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the current line at the |
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R k 1 |
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cylinder surface |
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Angular component of |
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1 Uc R, |
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Hc |
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tk cos(k ) |
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the field intensity |
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R k 1 |
The field intensity induced by the current line may be calculated directly
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Definition of coefficients
At the surface of the cylinder:
U (1) Um(2) Uc( 2)
Hn(1) 0 Hn(2)m 0 Hn(2)c
Relative magnetic |
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permeability |
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Solution of the system:
ck Rk dk R k |
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tk |
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2 k |
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kck R |
k 1 |
0kdk R |
k 1 |
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k 1 |
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2 bk |
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k 0 |
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System for series |
ck |
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dk R |
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2 k |
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coefficients |
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k |
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r ck R |
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dk |
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ck R |
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r R |
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Rk |
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i r 1 |
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ck |
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dk |
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Solution of the problem
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Scalar potential: |
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sin k , |
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k |
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r 1 k 1 |
k b |
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1 R2k |
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Reduced potential: |
Um |
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sin k , |
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Magnetic field on the system axis 0 :
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rk 1 |
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k 1 |
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Hm Hm |
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r R |
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2 r 1 k 1 |
b r |
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Magnetic field directions
0
R
Hm
O |
H |
Hc r b |
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Inductance of the two-wire transmission line per unit length
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0 |
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r a |
r b |
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Total inductance: |
L L2wire L |
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L2wire Is the inductance of 2-wire line without a cylinder
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