lcapy.loopanalysis.LoopAnalysis

class lcapy.loopanalysis.LoopAnalysis(cct)

Bases: object

This performs for loop analysis. Currently, it uses mesh analysis and so is only applicable to circuits with a planar topology and without twoport components.

Note, the loops are found using Networkx and since this uses unordered Python sets, different invocations can find different current loops for the same circuit.

>>> from lcapy import Circuit, LoopAnalysis
>>> cct = Circuit('''
... V1 1 0 {u(t)}; down
... R1 1 2; right=2
... L1 2 3; down=2
... W1 0 3; right
... W 1 5; up
... W 2 6; up
... C1 5 6; right=2
...''')

To perform loop analysis in the time domain:

>>> la = LoopAnalysis(cct)

To display the equations found by applying KVL around each mesh:

>>> la.mesh_equations().pprint()

To display the system of equations (in matrix form) that needs to be solved:

>>> la.matrix_equations().pprint()

This only works for dc, ac, or laplace domains. For example,

>>> LoopAnalysis(cct.laplace()).matrix_equations().pprint()

Methods

__init__(cct)
from_circuit(cct)
loops()	Return list of loops.
loops_by_cpt_name()	Return list of loops specified by cpt name.
matrix_equations([form, invert])	Return the equations in matrix form.
mesh_currents()	Return list of mesh current names.
mesh_equations()	Return mesh equations as a dict keyed by the mesh current.
mesh_equations_list()	Return mesh equations as a list.
pdb()	Enter the python debugger.
solve_laplace()	Determine the unknown voltages using Laplace transforms and return as a dict

Attributes

A	Return A matrix where A y = b.
b	Return b vector where A y = b.
num_loops
unknowns	Return tuple of the unknown voltages
y	Return y vector where A y = b.

property A

Return A matrix where A y = b.

property b

Return b vector where A y = b.

loops()

Return list of loops. Note, the loops can vary for different invocations of the LoopAnalysis class.

loops_by_cpt_name()

Return list of loops specified by cpt name.

matrix_equations(form='default', invert=False)

Return the equations in matrix form.

Forms can be:

‘default’ ‘A y = b’ ‘b = A y’ ‘Ainv b = y’ ‘y = Ainv b’

If invert is True, evaluate the matrix inverse.

mesh_currents()

Return list of mesh current names.

mesh_equations()

Return mesh equations as a dict keyed by the mesh current.

mesh_equations_list()

Return mesh equations as a list.

pdb()

Enter the python debugger.

solve_laplace()

Determine the unknown voltages using Laplace transforms and return as a dict

property unknowns

Return tuple of the unknown voltages

property y

Return y vector where A y = b.