| Coupled inductors |
Couples two or more inductors. The general form of the instance of a coupled inductors is the following:
| K<name> <Lname> <Lname> [Lname]* <coupling value> |
name
Is the name of the component and the initial letter K identifies the coupled inductors. The polarity is determined by the order of the nodes in the L devices and not by the order of inductors in the K statement. The positive node, containing the point, must be first defined in the instance of the inductor.
value
This is the coefficient of mutual coupling, which must be between -1.0 and 1.0.
KTR L1 L2 0.8
For U.C. Berkeley SPICE: if there are several coils on a transformer, then there must be K statements coupling all combinations of inductor pairs. For instance, a transformer using a center-tapped primary and two secondaries could be written:
*PRIMARY
L1 1 2 10uH
L2 2 3 10uH
*SECONDARY
L3 11 12 10uH
L4 13 14 10uH
*MAGNETIC COUPLING
K12 L1 L2 1
K13 L1 L3 1
K14 L1 L4 1
K23 L2 L3 1
K24 L2 L4 1
K34 L3 L4 1
This older technique is still supported, but not required, for simulation. The same transformer can also be written:
*PRIMARY
L1 1 2 10uH
L2 2 3 10uH
*SECONDARY
L3 11 12 10uH
L4 13 14 10uH
*MAGNETIC COUPLING
K1 L1 L2 L3 L4 1