python - Python signal.TransferFunction --> RuntimeWarning: 在 true_divide 中遇到除以零

Question

我正在尝试使用 python 绘制离散 PID 控制器的传递函数。我收到非常奇怪的错误消息，我无法解决。

from pylab import *
from scipy import signal
Ts = 0.001

Kp = 50
Ki = 10
Kd = 300

K1 = Kp + Ki + Kd
K2 = -1 * Kp - (2 * Kd)
K3 = Kd

system = signal.TransferFunction([K1, K2, K3], [1, -1], dt=0.001)
w, mag, phase = system.bode()

print(system)

plt.figure()
plt.semilogx(w, mag)    # Bode magnitude plot
plt.figure()
plt.semilogx(w, phase)  # Bode phase plot
plt.show()

print("Done")

这给出了这个错误：

Done
C:\Matthijs\Python\matthijs_env\lib\site-packages\scipy\signal\filter_design.py:474: RuntimeWarning: divide by zero encountered in true_divide
  h = (npp_polyval(zm1, b, tensor=False) /
C:\Matthijs\Python\matthijs_env\lib\site-packages\scipy\signal\filter_design.py:474: RuntimeWarning: invalid value encountered in true_divide
  h = (npp_polyval(zm1, b, tensor=False) /
C:\Matthijs\Python\matthijs_env\lib\site-packages\numpy\lib\function_base.py:1540: RuntimeWarning: invalid value encountered in remainder
  ddmod = mod(dd + pi, 2*pi) - pi

我迷路了，因为这应该是一个有效的传递函数。

离散 PID 的增益图