Create rectangular_pulse_wave.py

Author: josh-hrisko

rectangular_pulse_wave.py

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+# plotting rectangular pulse waves for PWM visualization
+#
+import numpy as np
+import matplotlib.pyplot as plt
+
+# plotting routine
+fig,ax = plt.subplots(figsize=(16,10))
+ax.grid(True,color='#FCFCFC',linewidth=1.5)
+ax.set_facecolor('#e6e6e6')
+ax.set_ylim([-0.8,5.99])
+ax.set_xlabel('Time [s]',fontsize=26,labelpad=15)
+ax.set_ylabel('Amplitude [V]',fontsize=26,labelpad=15)
+ax.tick_params('both',labelsize=16)
+
+D = 0.5 # duty cycle [%]
+T = 0.02 # period in seconds
+tau = D*T # pulse duration
+n_size = 10000 # size of the Fourier sum
+n = np.linspace(1.0,n_size,n_size) # vector for Fourier sum
+
+periods_to_plot = 3 # how many periods to plot in figure
+t = np.linspace(0.0,T*periods_to_plot,1000) # time vector
+t_shift = t - (tau/2.0) # shift about zero point to capture full first cycle
+
+f_t = [] # rectangular pulse variable
+for t_i in t_shift:
+    f_t.append(5.0*((tau/T) + np.sum((2.0/(n*np.pi))*(np.sin((np.pi*n*tau)/(T)))*(np.cos((2.0*np.pi*n*t_i)/(T))))))
+
+# annotations to show duty cycle, period, off band
+annot1 = ax.annotate("", xy=(T, 5.25), xytext=(T+tau, 5.25),
+             arrowprops=dict(arrowstyle="|-|",facecolor='k',
+                             linewidth=3))
+txt1 = ax.text(T+(tau/2.0),5.6,'{0:2.0f}% Duty Cycle ({1:2.0f}ms)'.format(D*100.0,tau*1000.0),
+        {'color': 'black', 'fontsize': 12, 'ha': 'center', 'va': 'center',
+         'bbox': dict(boxstyle="round", fc="#FCFCFC", ec="#FCFCFC", pad=0.6)})
+annot2 = ax.annotate("", xy=(T, -0.25), xytext=(2.0*T, -0.25),
+             arrowprops=dict(arrowstyle="|-|",facecolor='k',
+                             linewidth=3))
+txt2 = ax.text(T+(T/2.0),-0.5,'{0:2.0f}ms Period ({1:2.0f}Hz)'.format(T*1000.0,1.0/T),
+        {'color': 'black', 'fontsize': 12, 'ha': 'center', 'va': 'center',
+         'bbox': dict(boxstyle="round", fc="#FCFCFC", ec="#FCFCFC", pad=0.6)})
+ax.plot(t,f_t,linewidth=4,color=plt.cm.Set1(1))
+plt.show()