rodrigomoliveira1
commented
3 years ago Hello @tonylee2016! it's great to see your enthusiasm for contributing to ROSS.
Currently, we have a class to build a magnetic bearing. It's called MagneticBearingElement (see code below from ross/bearing_seal_element.py).
You can take a step forward from what we have now. You're welcome to propose any improvement to the code.
@davidjgm is the one responsible for add this content to ROSS. I believe you both can help each other, if it's the case.
class MagneticBearingElement(BearingElement):
"""Magnetic bearing.
This class creates a magnetic bearing element.
Converts electromagnetic parameters and PID gains to stiffness and damping
coefficients.
Parameters
----------
n : int
The node in which the magnetic bearing will be located in the rotor.
g0 : float
Air gap in m^2.
i0 : float
Bias current in Ampere
ag : float
Pole area in m^2.
nw : float or int
Number of windings
alpha : float or int
Pole angle in radians.
kp_pid : float or int
Proportional gain of the PID controller.
kd_pid : float or int
Derivative gain of the PID controller.
k_amp : float or int
Gain of the amplifier model.
k_sense : float or int
Gain of the sensor model.
tag : str, optional
A tag to name the element
Default is None.
n_link : int, optional
Node to which the bearing will connect. If None the bearing is
connected to ground.
Default is None.
scale_factor : float, optional
The scale factor is used to scale the bearing drawing.
Default is 1.
----------
See the following reference for the electromagnetic parameters g0, i0, ag, nw, alpha:
Book: Magnetic Bearings. Theory, Design, and Application to Rotating Machinery
Authors: Gerhard Schweitzer and Eric H. Maslen
Page: 84-95
Examples
--------
>>> n = 0
>>> g0 = 1e-3
>>> i0 = 1.0
>>> ag = 1e-4
>>> nw = 200
>>> alpha = 0.392
>>> kp_pid = 1.0
>>> kd_pid = 1.0
>>> k_amp = 1.0
>>> k_sense = 1.0
>>> tag = "magneticbearing"
>>> mbearing = MagneticBearingElement(n=n, g0=g0, i0=i0, ag=ag, nw=nw,alpha=alpha,
... kp_pid=kp_pid, kd_pid=kd_pid, k_amp=k_amp,
... k_sense=k_sense)
>>> mbearing.kxx
[-4640.623377181318]
"""
def __init__(
self,
n,
g0,
i0,
ag,
nw,
alpha,
kp_pid,
kd_pid,
k_amp,
k_sense,
tag=None,
n_link=None,
scale_factor=1,
):
pL = [g0, i0, ag, nw, alpha, kp_pid, kd_pid, k_amp, k_sense]
pA = [0, 0, 0, 0, 0, 0, 0, 0, 0]
# Check if it is a number or a list with 2 items
for i in range(9):
if type(pL[i]) == float or int:
pA[i] = np.array(pL[i])
else:
if type(pL[i]) == list:
if len(pL[i]) > 2:
raise ValueError(
"Parameters must be scalar or a list with 2 items"
)
else:
pA[i] = np.array(pL[i])
else:
raise ValueError("Parameters must be scalar or a list with 2 items")
# From: "Magnetic Bearings. Theory, Design, and Application to Rotating Machinery"
# Authors: Gerhard Schweitzer and Eric H. Maslen
# Page: 354
ks = (
-4.0
* pA[1] ** 2.0
* np.cos(pA[4])
* 4.0
* np.pi
* 1e-7
* pA[3] ** 2.0
* pA[2]
/ (4.0 * pA[0] ** 3)
)
ki = (
4.0
* pA[1]
* np.cos(pA[4])
* 4.0
* np.pi
* 1e-7
* pA[3] ** 2.0
* pA[2]
/ (4.0 * pA[0] ** 2)
)
k = ki * pA[7] * pA[8] * (pA[5] + np.divide(ks, ki * pA[7] * pA[8]))
c = ki * pA[7] * pA[5] * pA[8]
# k = ki * k_amp*k_sense*(kp_pid+ np.divide(ks, ki*k_amp*k_sense))
# c = ki*k_amp*kd_pid*k_sense
# Get the parameters from k and c
if np.isscalar(k):
# If k is scalar, symmetry is assumed
kxx = k
kyy = k
else:
kxx = k[0]
kyy = k[1]
if np.isscalar(c):
# If c is scalar, symmetry is assumed
cxx = c
cyy = c
else:
cxx = c[0]
cyy = c[1]
super().__init__(
n=n,
frequency=None,
kxx=kxx,
kxy=0.0,
kyx=0.0,
kyy=kyy,
cxx=cxx,
cxy=0.0,
cyx=0.0,
cyy=cyy,
tag=tag,
n_link=n_link,
scale_factor=scale_factor,
)
davidjgm
tonylee2016
ross-bott
mcarolalb
raphaeltimbo
Glad to see a rotordynamics simulation package in python. I had a plan to do so when studied at Texas A&M.
I can contribute to improving the AMB module