basic PWM model

RL Testing/PWM_Circuit_Model.py

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+import numpy as np
+import matplotlib.pyplot as plt
+from scipy.signal import TransferFunction, lsim
+
+# ---- Parameters (edit these) ----
+R = 1.5          # ohms
+L = 0.0025       # henries
+V = 12.0         # volts
+
+# Time base
+t_end = 0.2
+dt = 1e-4
+t = np.arange(0, t_end, dt)
+
+# ---- Define a duty command D(t) ----
+# Example: start at 0, step to 0.2 at 20 ms, then to 0.6 at 80 ms, then to 1.0 at 140 ms (DC full on)
+D = np.zeros_like(t)
+D[t >= 0.020] = 0.2
+D[t >= 0.080] = 0.6
+D[t >= 0.140] = 1.0  # "straight DC" case (100% duty)
+
+# Clamp just in case
+D = np.clip(D, 0.0, 1.0)
+
+# ---- Transfer function I(s)/D(s) = V / (L s + R) ----
+# In scipy.signal.TransferFunction, numerator/denominator are polynomials in s
+G = TransferFunction([V], [L, R])
+
+# Simulate i(t) response to input D(t)
+tout, i, _ = lsim(G, U=D, T=t)
+
+# ---- Print steady-state expectations ----
+# For constant duty D0, steady-state i_ss = (V/R)*D0
+print("Expected steady-state currents (V/R * D):")
+for D0 in [0.0, 0.2, 0.6, 1.0]:
+    print(f"  D={D0:.1f} -> i_ss ~ {(V/R)*D0:.3f} A")
+
+
+# ---- Plot ----
+plt.figure()
+plt.plot(tout, D, label="Duty D(t)")
+plt.plot(tout, i, label="Current i(t) [A]")
+plt.xlabel("Time [s]")
+plt.grid(True)
+plt.legend()
+plt.show()
+