User`s guide

Control System Parts 6
-25
An Instantaneous Device
Example: Modelin
g
a Triode
This section provides an example of using various ABM parts to
model a triode vacuum tube. The schematic of the triode
subcircuit is shown in Figure 6-13.
Fi
g
ure 6-13
Triode Circuit
Assumptions: In its main operating region, the triode’s current
is proportional to the 3/2 power of a linear combination of the
grid and anode voltages:
ianode = k
0
*(v
g
+ k
1
*va)
1.5
For a typical triode, k
0
= 200e-6 and k
1
= 0.12.
Looking at the upper left-hand portion of the schematic, notice
the a general-purpose ABM part used to take the input voltages
from anode, grid, and cathode. Assume the following
associations:
• V(anode) is associated with V(%IN1)
• V(grid) is associated with V(%IN2)
• V(cathode) is associated with V(%IN3)
The expression attribute EXP1 then represents V(grid, cathode)
and the expression attribute EXP2 represents 0.12[V(anode,
cathode)]. When the template substitution is performed, the
resulting VALUE is equivalent to the following:
V = V(grid, cathode) + 0.12*V(anode, cathode)
The part would be defined with the following characteristics: