3-phase half-bridge rectifier
The three-phase half bridge diode rectifier given below is connected to a three-phase ac voltage source. The resistance $R$ is $10\,\Omega$.- Plot the voltage across $R$ and current through the diodes.
- Find the average and RMS values of the voltage across $R$.
- What is the power delivered to $R$?
- Find the RMS values of the diode currents.
- Find the RMS value of the fundamental component of the ac line current.
- What is the angle between the phase voltage $V_an(t)$ and line current?
- Find the input power factor.
- What is the THD of the input current?
- Which are the dominant harmonics in the ac line current?
In [1]:
from IPython.display import Image
Image(filename =r'rectifier_3ph_1_fig_1.png', width=320)
Out[1]:
In [2]:
# run this cell to view the circuit file.
%pycat rectifier_3ph_1_orig.in
We now replace the strings such as \$R with the values of our choice by running the python script given below. It takes an existing circuit file rectifier_3ph_1_orig.in and produces a new circuit file rectifier_3ph_1.in, after replacing \$R (etc) with values of our choice.
In [3]:
import gseim_calc as calc
import numpy as np
s_R = "10"
VL = 400.0
A_sin = VL*np.sqrt(2/3)
s_A_sin = ("%11.4E"%(A_sin)).strip()
l = [
('$R', s_R),
('$A_sin', s_A_sin),
]
calc.replace_strings_1("rectifier_3ph_1_orig.in", "rectifier_3ph_1.in", l)
print('rectifier_3ph_1.in is ready for execution')
rectifier_3ph_1.in is ready for execution
Execute the following cell to run GSEIM on rectifier_3ph_1.in.
In [4]:
import os
import dos_unix
# uncomment for windows:
#dos_unix.d2u("rectifier_3ph_1.in")
os.system('run_gseim rectifier_3ph_1.in')
get_lib_elements: filename gseim_aux/xbe.aux get_lib_elements: filename gseim_aux/ebe.aux Circuit: filename = rectifier_3ph_1.in Circuit: n_xbeu_vr = 0 Circuit: n_ebeu_nd = 5 main: i_solve = 0 main: calling solve_trns Transient simulation starts... i=0 GSEIM: Program completed.
Out[4]:
0
The circuit file (rectifier_3ph_1.in) is created in the same directory as that used for launching Jupyter notebook. The last step (i.e., running GSEIM on rectifier_3ph_1.in) creates data files called rectifier_3ph_1_1.dat, etc. in the same directory. We can now use the python code below to compute/plot the various quantities of interest.
In [5]:
import numpy as np
import matplotlib.pyplot as plt
import gseim_calc as calc
from setsize import set_size
f_hz = 50.0
T = 1.0/f_hz
slv = calc.slv("rectifier_3ph_1.in")
i_slv = 0
i_out = 0
filename = slv.l_filename_all[i_slv][i_out]
print('filename:', filename)
u1 = np.loadtxt(filename)
t1 = u1[:, 0]
col_IR = slv.get_index(i_slv,i_out,"IR")
col_ID1 = slv.get_index(i_slv,i_out,"ID1")
col_ID2 = slv.get_index(i_slv,i_out,"ID2")
col_ID3 = slv.get_index(i_slv,i_out,"ID3")
col_v_out = slv.get_index(i_slv,i_out,"v_out")
i_out = 1
filename = slv.l_filename_all[i_slv][i_out]
print('filename:', filename)
u2 = np.loadtxt(filename)
t2 = u2[:, 0]
col_P_R = slv.get_index(i_slv,i_out,"P_R")
col_P_Vsa = slv.get_index(i_slv,i_out,"P_Vsa")
col_P_Vsb = slv.get_index(i_slv,i_out,"P_Vsb")
col_P_Vsc = slv.get_index(i_slv,i_out,"P_Vsc")
l_v_out = calc.avg_rms_2(t1, u1[:,col_v_out], T, 2.0*T, 1.0e-5*T)
l_P_R = calc.avg_rms_2(t2, u2[:,col_P_R ], T, 2.0*T, 1.0e-5*T)
l_P_Vsa = calc.avg_rms_2(t2, u2[:,col_P_Vsa], T, 2.0*T, 1.0e-5*T)
l_ID1 = calc.avg_rms_2(t1, u1[:,col_ID1 ], T, 2.0*T, 1.0e-5*T)
# get A_sin from the circuit file:
fin = open("rectifier_3ph_1.in", "r")
for line in fin:
if 'name=Vsa' in line:
for s in line.split():
if s.startswith('a='):
A_sin = float(s.split('=')[1])
fin.close()
print('average value of v_out:' , "%11.4E"%l_v_out[1][0])
print('rms value of v_out:' , "%11.4E"%l_v_out[2][0])
print('average power delivered to R:' , "%11.4E"%l_P_R [1][0])
print('rms value of ID1:' , "%11.4E"%l_ID1 [2][0])
print('average power delivered by Vsa:', "%11.4E"%l_P_Vsa[1][0])
Irms = l_ID1[2][0]
Vrms = A_sin/np.sqrt(2.0)
pf = l_P_Vsa[1][0]/(Vrms*Irms)
print('input power factor:', "%6.3f"%pf)
color1='red'
color2='goldenrod'
color3='blue'
color4='green'
color5='crimson'
color6='cornflowerblue'
fig, ax = plt.subplots(4, sharex=False)
plt.subplots_adjust(wspace=0, hspace=0.0)
set_size(5.5, 8, ax[0])
for i in range(4):
ax[i].set_xlim(left=0.0, right=2.0*T*1e3)
ax[i].grid(color='#CCCCCC', linestyle='solid', linewidth=0.5)
ax[0].set_ylabel(r'$V_R$', fontsize=12)
ax[1].set_ylabel(r'$I_{D1}$', fontsize=12)
ax[2].set_ylabel(r'$I_{D2}$', fontsize=12)
ax[3].set_ylabel(r'$I_{D3}$', fontsize=12)
ax[0].tick_params(labelbottom=False)
ax[1].tick_params(labelbottom=False)
ax[2].tick_params(labelbottom=False)
ax[0].plot(t1*1e3, u1[:,col_v_out], color=color4, linewidth=1.0, label="$V_R$")
ax[1].plot(t1*1e3, u1[:,col_ID1], color=color1, linewidth=1.0, label="$I_{D1}$")
ax[2].plot(t1*1e3, u1[:,col_ID2], color=color2, linewidth=1.0, label="$I_{D2}$")
ax[3].plot(t1*1e3, u1[:,col_ID3], color=color3, linewidth=1.0, label="$I_{D3}$")
ax[3].set_xlabel('time (msec)', fontsize=12)
#plt.tight_layout()
plt.show()
filename: rectifier_3ph_1_1.dat filename: rectifier_3ph_1_2.dat average value of v_out: 2.7009E+02 rms value of v_out: 2.7456E+02 average power delivered to R: 7.5385E+03 rms value of ID1: 1.5845E+01 average power delivered by Vsa: 2.5107E+03 input power factor: 0.686
In [6]:
import numpy as np
import matplotlib.pyplot as plt
import gseim_calc as calc
from setsize import set_size
f_hz = 50.0
T = 1.0/f_hz
slv = calc.slv("rectifier_3ph_1.in")
i_slv = 0
i_out = 0
filename = slv.l_filename_all[i_slv][i_out]
print('filename:', filename)
u1 = np.loadtxt(filename)
t1 = u1[:, 0]
col_IR = slv.get_index(i_slv,i_out,"IR")
col_ID1 = slv.get_index(i_slv,i_out,"ID1")
col_ID2 = slv.get_index(i_slv,i_out,"ID2")
col_ID3 = slv.get_index(i_slv,i_out,"ID3")
col_v_out = slv.get_index(i_slv,i_out,"v_out")
i_out = 1
filename = slv.l_filename_all[i_slv][i_out]
print('filename:', filename)
u2 = np.loadtxt(filename)
t2 = u2[:, 0]
col_P_R = slv.get_index(i_slv,i_out,"P_R")
col_P_Vsa = slv.get_index(i_slv,i_out,"P_Vsa")
col_P_Vsb = slv.get_index(i_slv,i_out,"P_Vsb")
col_P_Vsc = slv.get_index(i_slv,i_out,"P_Vsc")
# get A_sin from the circuit file:
fin = open("rectifier_3ph_1.in", "r")
for line in fin:
if 'name=Vsa' in line:
for s in line.split():
if s.startswith('a='):
A_sin = float(s.split('=')[1])
fin.close()
# compute Fourier coeffs:
t_start = T
t_end = 2.0*T
n_fourier = 20
coeff_ID1, thd1_ID1, thd2_ID1 = calc.fourier_coeff_1A(t1, u1[:,col_ID1],
t_start, t_end, 1.0e-8, n_fourier)
coeff_v_out, thd_v_out = calc.fourier_coeff_1C(t1, u1[:,col_v_out],
t_start, t_end, 1.0e-8, n_fourier)
print("input current fundamental: RMS value: ", "%11.4E"%(coeff_ID1[1]/np.sqrt(2.0)))
print("input current THD (without dc term): ", "%11.4E"%thd1_ID1)
print("input current THD (with dc term): ", "%11.4E"%thd2_ID1)
x = np.linspace(0, n_fourier, n_fourier+1)
y_v_out = np.array(coeff_v_out)
y_ID1 = np.array(coeff_ID1 )
fig, ax = plt.subplots(2, sharex=False)
plt.subplots_adjust(wspace=0, hspace=0.0)
grid_color='#CCCCCC'
set_size(6, 4, ax[0])
delta = 5.0
x_major_ticks = np.arange(0.0, (float(n_fourier+1)), delta)
x_minor_ticks = np.arange(0.0, (float(n_fourier+1)), 1.0)
for i in range(2):
ax[i].set_xlim(left=-1.0, right=float(n_fourier))
ax[i].set_xticks(x_major_ticks)
ax[i].set_xticks(x_minor_ticks, minor=True)
ax[i].grid(visible=True, which='major', axis='x', color=grid_color, linestyle='-', zorder=0)
ax[0].set_ylabel('$V_{out}$',fontsize=14)
ax[1].set_ylabel('$i_{D1}$',fontsize=14)
bars1 = ax[0].bar(x, y_v_out, width=0.3, color='red', label="$V_{out}$", zorder=3)
bars2 = ax[1].bar(x, y_ID1 , width=0.3, color='green', label="$i_{D1}$" , zorder=3)
plt.tight_layout()
plt.show()
filename: rectifier_3ph_1_1.dat filename: rectifier_3ph_1_2.dat input current fundamental: RMS value: 1.0872E+01 input current THD (without dc term): 6.6371E-01 input current THD (with dc term): 1.0603E+00
In [7]:
import math
import numpy as np
import matplotlib.pyplot as plt
import gseim_calc as calc
from setsize import set_size
f_hz = 50.0
T = 1.0/f_hz
slv = calc.slv("rectifier_3ph_1.in")
i_slv = 0
i_out = 0
filename = slv.l_filename_all[i_slv][i_out]
print('filename:', filename)
u1 = np.loadtxt(filename)
t1 = u1[:, 0]
col_IR = slv.get_index(i_slv,i_out,"IR")
col_ID1 = slv.get_index(i_slv,i_out,"ID1")
col_ID2 = slv.get_index(i_slv,i_out,"ID2")
col_ID3 = slv.get_index(i_slv,i_out,"ID3")
col_v_out = slv.get_index(i_slv,i_out,"v_out")
# get A_sin from the circuit file:
fin = open("rectifier_3ph_1.in", "r")
for line in fin:
if 'name=Vsa' in line:
for s in line.split():
if s.startswith('a='):
A_sin = float(s.split('=')[1])
fin.close()
# compute Fourier coeffs:
t_start = T
t_end = 2.0*T
n_fourier = 20
coeff_ID1, thd_ID1, coeff_a_ID1, coeff_b_ID1 = calc.fourier_coeff_2A(
t1, u1[:,col_ID1], t_start, t_end, 1.0e-8, n_fourier)
t_ID1, y_ID1 = calc.construct_fourier_component(1, coeff_a_ID1, coeff_b_ID1, 0.0, T, 2, 200)
omg = f_hz*2.0*np.pi
vs_a = A_sin*np.sin(omg*t_ID1)
theta1 = math.atan2(-coeff_b_ID1[1], coeff_a_ID1[1])*180.0/math.pi
# if ID1 was written as k * sin (w*t + theta), what would theta be?
theta = theta1 + 90.0
print('angle of i_a w.r.t. V_a:', "%11.4E"%theta)
color1='green'
color2='crimson'
color3='cornflowerblue'
fig, ax = plt.subplots(2, sharex=False)
plt.subplots_adjust(wspace=0, hspace=0.0)
set_size(5.5, 5, ax[0])
for i in range(2):
ax[i].set_xlim(left=0.0, right=2.0*T*1e3)
ax[i].grid(color='#CCCCCC', linestyle='solid', linewidth=0.5)
ax[0].plot(t1*1e3, u1[:,col_ID1], color=color1, linewidth=1.0, label="$i_{D1}$")
ax[0].plot(t_ID1*1e3, y_ID1, color=color2, linewidth=1.0, linestyle='--', dashes=(5,3),
label="$i_{D1}\,(1)$")
ax[1].plot(t_ID1*1e3, vs_a, color=color3, linewidth=1.0, label="$V_a$")
ax[1].set_xlabel('time (msec)', fontsize=12)
for i in range(2):
ax[i].legend(loc = 'lower right',frameon = True, fontsize = 10, title = None,
markerfirst = True, markerscale = 1.0, labelspacing = 0.5, columnspacing = 2.0,
prop = {'size' : 12},)
plt.tight_layout()
plt.show()
filename: rectifier_3ph_1_1.dat angle of i_a w.r.t. V_a: 1.4211E-14
This notebook was contributed by Prof. Nakul Narayanan K, Govt. Engineering College, Thrissur. He may be contacted at nakul@gectcr.ac.in.