import numpy as np
[docs]
class ElementError(Exception):
...
[docs]
class OverwriteError(ElementError):
...
[docs]
def element(num_params, units, overwrite=False):
"""decorator to store metadata for a circuit element
Parameters
----------
num_params : int
number of parameters for an element
units : list of str
list of units for the element parameters
overwrite : bool (default False)
if true, overwrites any existing element; if false,
raises OverwriteError if element name already exists.
"""
def decorator(func):
def wrapper(p, f):
typeChecker(p, f, func.__name__, num_params)
return func(p, f)
wrapper.num_params = num_params
wrapper.units = units
wrapper.__name__ = func.__name__
wrapper.__doc__ = func.__doc__
global circuit_elements
if func.__name__ in ["s", "p"]:
raise ElementError("cannot redefine elements 's' (series)" +
"or 'p' (parallel)")
elif func.__name__ in circuit_elements and not overwrite:
raise OverwriteError(
f"element {func.__name__} already exists. " +
"If you want to overwrite the existing element," +
"use `overwrite=True`."
)
else:
circuit_elements[func.__name__] = wrapper
# Adding numpy to circuit_elements for proper evaluation with
# numpy>=2.0.0 because the scalar representation was changed.
# "Scalars are now printed as np.float64(3.0) rather than just 3.0."
# https://numpy.org/doc/2.0/release/2.0.0-notes.html
# #representation-of-numpy-scalars-changed
circuit_elements["np"] = np
return wrapper
return decorator
[docs]
def s(series):
"""sums elements in series
Notes
---------
.. math::
Z = Z_1 + Z_2 + ... + Z_n
"""
z = len(series[0]) * [0 + 0 * 1j]
for elem in series:
z += elem
return z
[docs]
def p(parallel):
"""adds elements in parallel
Notes
---------
.. math::
Z = \\frac{1}{\\frac{1}{Z_1} + \\frac{1}{Z_2} + ... + \\frac{1}{Z_n}}
"""
z = len(parallel[0]) * [0 + 0 * 1j]
for elem in parallel:
z += 1 / elem
return 1 / z
# manually add parallel and series operators to circuit elements w/o metadata
# populated by the element decorator -
# this maps ex. 'R' to the function R to always give us a list of
# active elements in any context
circuit_elements = {"s": s, "p": p}
[docs]
@element(num_params=1, units=["Ohm"])
def R(p, f):
"""defines a resistor
Notes
---------
.. math::
Z = R
"""
R = p[0]
Z = np.array(len(f) * [R])
return Z
[docs]
@element(num_params=1, units=["F"])
def C(p, f):
"""defines a capacitor
.. math::
Z = \\frac{1}{C \\times j 2 \\pi f}
"""
omega = 2 * np.pi * np.array(f)
C = p[0]
Z = 1.0 / (C * 1j * omega)
return Z
[docs]
@element(num_params=1, units=["H"])
def L(p, f):
"""defines an inductor
.. math::
Z = L \\times j 2 \\pi f
"""
omega = 2 * np.pi * np.array(f)
L = p[0]
Z = L * 1j * omega
return Z
[docs]
@element(num_params=1, units=["Ohm sec^-1/2"])
def W(p, f):
"""defines a semi-infinite Warburg element
Notes
-----
.. math::
Z = \\frac{A_W}{\\sqrt{ 2 \\pi f}} (1-j)
"""
omega = 2 * np.pi * np.array(f)
Aw = p[0]
Z = Aw * (1 - 1j) / np.sqrt(omega)
return Z
[docs]
@element(num_params=2, units=["Ohm", "sec"])
def Wo(p, f):
"""defines an open (finite-space) Warburg element
Notes
---------
.. math::
Z = \\frac{Z_0}{\\sqrt{ j \\omega \\tau }}
\\coth{\\sqrt{j \\omega \\tau }}
where :math:`Z_0` = p[0] (Ohms) and
:math:`\\tau` = p[1] (sec) = :math:`\\frac{L^2}{D}`
"""
omega = 2 * np.pi * np.array(f)
Z0, tau = p[0], p[1]
Z = Z0 / (np.sqrt(1j * omega * tau) * np.tanh(np.sqrt(1j * omega * tau)))
return Z # Zw(omega)
[docs]
@element(num_params=2, units=["Ohm", "sec"])
def Ws(p, f):
"""defines a short (finite-length) Warburg element
Notes
---------
.. math::
Z = \\frac{Z_0}{\\sqrt{ j \\omega \\tau }}
\\tanh{\\sqrt{j \\omega \\tau }}
where :math:`Z_0` = p[0] (Ohms) and
:math:`\\tau` = p[1] (sec) = :math:`\\frac{L^2}{D}`
"""
omega = 2 * np.pi * np.array(f)
Z0, tau = p[0], p[1]
Z = Z0 * np.tanh(np.sqrt(1j * omega * tau)) / np.sqrt(1j * omega * tau)
return Z
[docs]
@element(num_params=2, units=["Ohm^-1 sec^a", ""])
def CPE(p, f):
"""defines a constant phase element
Notes
-----
.. math::
Z = \\frac{1}{Q \\times (j 2 \\pi f)^\\alpha}
where :math:`Q` = p[0] and :math:`\\alpha` = p[1].
"""
omega = 2 * np.pi * np.array(f)
Q, alpha = p[0], p[1]
Z = 1.0 / (Q * (1j * omega) ** alpha)
return Z
[docs]
@element(num_params=2, units=["H sec", ""])
def La(p, f):
"""defines a modified inductance element as represented in [1]
Notes
-----
.. math::
Z = L \\times (j 2 \\pi f)^\\alpha
where :math:`L` = p[0] and :math:`\\alpha` = p[1]
[1] `EC-Lab Application Note 42, BioLogic Instruments (2019)
<https://www.biologic.net/documents/battery-eis-modified-inductance-element-electrochemsitry-application-note-42>`_.
"""
omega = 2 * np.pi * np.array(f)
L, alpha = p[0], p[1]
Z = (L * 1j * omega) ** alpha
return Z
[docs]
@element(num_params=2, units=["Ohm", "sec"])
def G(p, f):
"""defines a Gerischer Element as represented in [1]
Notes
---------
.. math::
Z = \\frac{R_G}{\\sqrt{1 + j \\, 2 \\pi f \\, t_G}}
where :math:`R_G` = p[0] and :math:`t_G` = p[1]
Gerischer impedance is also commonly represented as [2]:
.. math::
Z = \\frac{Z_o}{\\sqrt{K+ j \\, 2 \\pi f}}
where :math:`Z_o = \\frac{R_G}{\\sqrt{t_G}}`
and :math:`K = \\frac{1}{t_G}`
with units :math:`\\Omega sec^{1/2}` and
:math:`sec^{-1}` , respectively.
[1] Y. Lu, C. Kreller, and S.B. Adler,
Journal of The Electrochemical Society, 156, B513-B525 (2009)
`doi:10.1149/1.3079337
<https://doi.org/10.1149/1.3079337>`_.
[2] M. González-Cuenca, W. Zipprich, B.A. Boukamp,
G. Pudmich, and F. Tietz, Fuel Cells, 1,
256-264 (2001) `doi:10.1016/0013-4686(93)85083-B
<https://doi.org/10.1016/0013-4686(93)85083-B>`_.
"""
omega = 2 * np.pi * np.array(f)
R_G, t_G = p[0], p[1]
Z = R_G / np.sqrt(1 + 1j * omega * t_G)
return Z
[docs]
@element(num_params=3, units=["Ohm", "sec", ""])
def Gs(p, f):
"""defines a finite-length Gerischer Element as represented in [1]
Notes
---------
.. math::
Z = \\frac{R_G}{\\sqrt{1 + j \\, 2 \\pi f \\, t_G} \\,
tanh(\\phi \\sqrt{1 + j \\, 2 \\pi f \\, t_G})}
where :math:`R_G` = p[0], :math:`t_G` = p[1] and :math:`\\phi` = p[2]
[1] R.D. Green, C.C Liu, and S.B. Adler,
Solid State Ionics, 179, 647-660 (2008)
`doi:10.1016/j.ssi.2008.04.024
<https://doi.org/10.1016/j.ssi.2008.04.024>`_.
"""
omega = 2 * np.pi * np.array(f)
R_G, t_G, phi = p[0], p[1], p[2]
Z = R_G / (
np.sqrt(1 + 1j * omega * t_G)
* np.tanh(phi * np.sqrt(1 + 1j * omega * t_G))
)
return Z
[docs]
@element(num_params=2, units=["Ohm", "sec"])
def K(p, f):
"""An RC element for use in lin-KK model
Notes
-----
.. math::
Z = \\frac{R}{1 + j \\omega \\tau_k}
"""
omega = 2 * np.pi * np.array(f)
R, tau_k = p[0], p[1]
Z = R / (1 + 1j * omega * tau_k)
return Z
[docs]
@element(num_params=3, units=['Ohm', 'sec', ''])
def Zarc(p, f):
""" An RQ element rewritten with resistance and
and time constant as paramenters. Equivalent to a
Cole-Cole relaxation in dielectrics.
Notes
-----
.. math::
Z = \\frac{R}{1 + (j \\omega \\tau_k)^\\gamma }
"""
omega = 2*np.pi*np.array(f)
R, tau_k, gamma = p[0], p[1], p[2]
Z = R/(1 + ((1j*omega*tau_k)**gamma))
return Z
[docs]
@element(num_params=3, units=["Ohm", "F sec^(gamma - 1)", ""])
def TLMQ(p, f):
"""Simplified transmission-line model as defined in Eq. 11 of [1]
Notes
-----
.. math::
Z = \\sqrt{R_{ion}Z_{S}} \\coth \\sqrt{\\frac{R_{ion}}{Z_{S}}}
[1] J. Landesfeind et al.,
Journal of The Electrochemical Society, 163 (7) A1373-A1387 (2016)
`doi: 10.1016/10.1149/2.1141607jes
<http://doi.org/10.1149/2.1141607jes>`_.
"""
omega = 2 * np.pi * np.array(f)
Rion, Qs, gamma = p[0], p[1], p[2]
Zs = 1 / (Qs * (1j * omega) ** gamma)
Z = np.sqrt(Rion * Zs) / np.tanh(np.sqrt(Rion / Zs))
return Z
[docs]
@element(num_params=4, units=["Ohm-m^2", "Ohm-m^2", "", "sec"])
def T(p, f):
"""A macrohomogeneous porous electrode model from Paasch et al. [1]
Notes
-----
.. math::
Z = A\\frac{\\coth{\\beta}}{\\beta} + B\\frac{1}{\\beta\\sinh{\\beta}}
where
.. math::
A = d\\frac{\\rho_1^2 + \\rho_2^2}{\\rho_1 + \\rho_2} \\quad
B = d\\frac{2 \\rho_1 \\rho_2}{\\rho_1 + \\rho_2}
and
.. math::
\\beta = (a + j \\omega b)^{1/2} \\quad
a = \\frac{k d^2}{K} \\quad b = \\frac{d^2}{K}
[1] G. Paasch, K. Micka, and P. Gersdorf,
Electrochimica Acta, 38, 2653–2662 (1993)
`doi: 10.1016/0013-4686(93)85083-B
<https://doi.org/10.1016/0013-4686(93)85083-B>`_.
"""
omega = 2 * np.pi * np.array(f)
A, B, a, b = p[0], p[1], p[2], p[3]
beta = (a + 1j * omega * b) ** (1 / 2)
sinh = []
for x in beta:
if x < 100:
sinh.append(np.sinh(x))
else:
sinh.append(1e10)
Z = A / (beta * np.tanh(beta)) + B / (beta * np.array(sinh))
return Z
def get_element_from_name(name):
excluded_chars = "0123456789_"
return "".join(char for char in name if char not in excluded_chars)
def typeChecker(p, f, name, length):
assert isinstance(p, list), \
"in {}, input must be of type list".format(name)
for i in p:
assert isinstance(
i, (float, int, np.int32, np.float64)
), "in {}, value {} in {} is not a number".format(name, i, p)
for i in f:
assert isinstance(
i, (float, int, np.int32, np.float64)
), "in {}, value {} in {} is not a number".format(name, i, f)
assert len(p) == length, "in {}, input list must be length {}".format(
name, length
)
return