Switching
Waveforms for the voltage $v(t)$ across and the current $i(t)$ through a switch during the turn-on and turn-off transitions are given below. The forward voltage drop across the switch when it is ON is $V_{on}$. The total energy dissipation in the switch during the switching transitions in one cycle (i.e., the energy dissipation in intervals $\Delta t_1$ and $\Delta t_2$ together) is $720\,\mu\,$J. If $I_1 = 20\,$A, $V_{on}= 2\,$V, $\Delta t_1 = \Delta t_2 = 20\,\mu$sec, find $V_1$.In [1]:
from IPython.display import Image
Image(filename =r'switching_2_fig_1.png', width=450)
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In [2]:
import numpy as np
import matplotlib.pyplot as plt
import gseim_calc as calc
from setsize import set_size
from scipy.interpolate import InterpolatedUnivariateSpline
I1 = 20.0
V1 = 30.0 # to be changed by user
Von = 2.0
delt0 = 2e-6
delt1 = 2e-6
delt1a = 8e-6
delt2 = 2e-6
delt3 = 2e-6
t0 = 0.0
t1 = t0 + delt0
t2 = t1 + delt1
t3 = t2 + delt1a
t4 = t3 + delt2
t5 = t4 + delt3
n_div = 2000
t = np.linspace(t0, t5, (n_div+1))
deltx = (t5-t0)/float(n_div)
slope_V = (V1-Von)/delt1
slope_I = I1/delt1
l_I = []
l_V = []
for i, tx in enumerate(t):
if tx < t1:
I = 0.0
V = V1
elif tx < t2:
delt = tx - t1
I = slope_I*delt
V = V1 - slope_V*delt
elif tx < t3:
I = I1
V = Von
elif tx < t4:
delt = tx - t3
I = I1 - slope_I*delt
V = Von + slope_V*delt
else:
I = 0.0
V = V1
l_I.append(I)
l_V.append(V)
np_I = np.array(l_I)
np_V = np.array(l_V)
P = np_I*np_V
P1 = InterpolatedUnivariateSpline(t, P, k=1) # k=1 gives linear interpolation
delE1 = P1.integral(t1, t2)
delE2 = P1.integral(t3, t4)
print('delE1:', "%7.2f"%(delE1*1e6), 'micro-Joules')
print('delE2:', "%7.2f"%(delE2*1e6), 'micro-Joules')
delEttl = delE1 + delE2
print('switching loss in transitions:', "%7.2f"%(delEttl*1e6), 'micro-Joules')
plot_min_P, plot_max_P = calc.delta_plot_1(P , 0.2)
plot_min_V, plot_max_V = calc.delta_plot_1(np_V, 0.2)
plot_min_I, plot_max_I = calc.delta_plot_1(np_I, 0.2)
color1='blue'
color2='red'
color3='green'
fig, ax = plt.subplots(3, sharex=False)
plt.subplots_adjust(wspace=0, hspace=0.0)
set_size(6.5, 5, ax[0])
for i in range(3):
ax[i].set_xlim(left=0.0, right=t5*1e6)
ax[i].grid(color='#CCCCCC', linestyle='solid', linewidth=0.5)
ax[0].set_ylim(bottom=plot_min_V, top=plot_max_V)
ax[1].set_ylim(bottom=plot_min_I, top=plot_max_I)
ax[2].set_ylim(bottom=plot_min_P, top=plot_max_P)
ax[0].set_ylabel(r'$v$', fontsize=12)
ax[1].set_ylabel(r'$i$', fontsize=12)
ax[2].set_ylabel(r'$p$', fontsize=12)
ax[0].tick_params(labelbottom=False)
ax[1].tick_params(labelbottom=False)
ax[0].plot(t*1e6, np_V, color=color1, linewidth=1.0, label="$v$")
ax[1].plot(t*1e6, np_I, color=color2, linewidth=1.0, label="$i$")
ax[2].plot(t*1e6, P , color=color3, linewidth=1.0, label="$p$")
ax[2].set_xlabel(r'time ($\mu$sec)', fontsize=12)
#plt.tight_layout()
plt.show()
delE1: 226.66 micro-Joules delE2: 226.66 micro-Joules switching loss in transitions: 453.33 micro-Joules
This notebook was contributed by Prof. Nakul Narayanan K, Govt. Engineering College, Thrissur. He may be contacted at nakul@gectcr.ac.in.
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