From 92cca121f959c6616e3da431c1e2d23c4fa5e886 Mon Sep 17 00:00:00 2001 From: hardythe1 Date: Tue, 7 Apr 2015 15:58:05 +0530 Subject: added books --- _Power_Electronics/Chapter7.ipynb | 1036 +++++++++++++++++++++++++++++++++++++ 1 file changed, 1036 insertions(+) create mode 100755 _Power_Electronics/Chapter7.ipynb (limited to '_Power_Electronics/Chapter7.ipynb') diff --git a/_Power_Electronics/Chapter7.ipynb b/_Power_Electronics/Chapter7.ipynb new file mode 100755 index 00000000..726160c8 --- /dev/null +++ b/_Power_Electronics/Chapter7.ipynb @@ -0,0 +1,1036 @@ +{ + "metadata": { + "name": "" + }, + "nbformat": 3, + "nbformat_minor": 0, + "worksheets": [ + { + "cells": [ + { + "cell_type": "heading", + "level": 1, + "metadata": {}, + "source": [ + "Chapter 07 : Choppers" + ] + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.2, Page No 387" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "a=0.4 #duty cycle %a=T_on/T\n", + "V_s=230.0\n", + "R=10.0\n", + "\n", + "#Calculations\n", + "V=a*(V_s-2) \n", + "V_or=math.sqrt(a*(V_s-2)**2) \n", + "P_o=V_or**2/R\n", + "P_i=V_s*V/R\n", + "n=P_o*100/P_i \n", + "\n", + "#Results\n", + "print(\"avg o/p voltage=%.1f V\" %V)\n", + "print(\"rms value of o/p voltage=%.1f V\" %V_or)\n", + "print(\"chopper efficiency in percentage=%.2f\" %n)" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "avg o/p voltage=91.2 V\n", + "rms value of o/p voltage=144.2 V\n", + "chopper efficiency in percentage=99.13\n" + ] + } + ], + "prompt_number": 1 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.3, Page No 388" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "V_i=220.0\n", + "V_o=660.0\n", + "\n", + "#Calculations\n", + "a=1-V_i/V_o\n", + "T_on=100.0 #microsecond\n", + "T=T_on/a\n", + "T_off=T-T_on \n", + "T_off=T_off/2\n", + "T_on=T-T_off\n", + "a=T_on/T\n", + "V_o=V_i/(1-a)\n", + "\n", + "#Results \n", + "print(\"pulse width of o/p voltage=%.0f us\" %T_off)\n", + "print(\"\\nnew o/p voltage=%.0f V\" %V_o)\n" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "pulse width of o/p voltage=25 us\n", + "\n", + "new o/p voltage=1320 V\n" + ] + } + ], + "prompt_number": 2 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.4 Page No 288" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "I_1=12.0\n", + "I_2=16.0\n", + "\n", + "#Calculations\n", + "I_0=(I_1+I_2)/2\n", + "R=10.0\n", + "V_0=I_0*R\n", + "V_s=200.0\n", + "a=V_0/V_s\n", + "r=a/(1-a)\n", + "\n", + "#Results\n", + "print(\"time ratio(T_on/T_off)=%.3f\" %r)\n" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "time ratio(T_on/T_off)=2.333\n" + ] + } + ], + "prompt_number": 3 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.5, Page No 390" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "V_o=660.0\n", + "V_s=220.0\n", + "\n", + "#Calculations\n", + "a=(V_o/V_s)/(1+(V_o/V_s))\n", + "T_on=120\n", + "T=T_on/a\n", + "T_off=T-T_on \n", + "T_off=3*T_off\n", + "T_on=T-T_off\n", + "a=T_on/(T_on+T_off)\n", + "V_o=V_s*(a/(1-a)) \n", + "\n", + "#Results\n", + "print(\"pulse width o/p voltage=%.0f us\" %T_off)\n", + "print(\"\\nnew o/p voltage=%.2f V\" %V_o)" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "pulse width o/p voltage=120 us\n", + "\n", + "new o/p voltage=73.33 V\n" + ] + } + ], + "prompt_number": 4 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.11 Page No 408" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "R=1.0\n", + "L=.005\n", + "T_a=L/R\n", + "T=2000*10**-6\n", + "E=24.0\n", + "V_s=220\n", + "T_on=600*10**-6\n", + "a=T_on/T\n", + "\n", + "#Calculations\n", + "a1=(T_a/T)*math.log(1+(E/V_s)*((math.exp(T/T_a))-1))\n", + "if a1a :\n", + " print(\"load current is continuous\")\n", + "else:\n", + " print(\"load current is discontinuous\")\n", + "\n", + "t_x=T_on+L*math.log(1+((V_s-E)/272)*(1-math.exp(-T_on/T_a)))\n", + " #Value of t_x wrongly calculated in the book so ans of V_o and I_o varies\n", + "V_o=a*V_s+(1-t_x/T)*E \n", + "I_o=(V_o-E)/R \n", + "I_mx=(V_s-E)/R*(1-math.exp(-T_on/T_a)) \n", + "\n", + "#Results \n", + "print(\"avg o/p voltage=%.2f V\" %V_o)\n", + "print(\"avg o/p current=%.2f A\" %I_o) \n", + "print(\"max value of load current=%.1f A\" %I_mx)" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "load current is discontinuous\n", + "avg o/p voltage=121.77 V\n", + "avg o/p current=49.77 A\n", + "max value of load current=81.5 A\n" + ] + } + ], + "prompt_number": 10 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.13, Page No 412" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "a=0.2\n", + "V_s=500\n", + "E=a*V_s\n", + "L=0.06\n", + "I=10\n", + "\n", + "#Calculations\n", + "T_on=(L*I)/(V_s-E)\n", + "f=a/T_on \n", + "\n", + "#Results\n", + "print(\"chopping freq=%.2f Hz\" %f)" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "chopping freq=133.33 Hz\n" + ] + } + ], + "prompt_number": 11 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.14 Page No 412" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "a=0.5\n", + "pu=0.1 #pu ripple\n", + "\n", + "#Calculations\n", + " #x=T/T_a\n", + " #y=exp(-a*x)\n", + "y=(1-pu)/(1+pu)\n", + " #after solving\n", + "x=math.log(1/y)/a\n", + "f=1000\n", + "T=1/f\n", + "T_a=T/x\n", + "R=2\n", + "L=R*T_a\n", + "Li=0.002\n", + "Le=L-Li \n", + "\n", + "#Results\n", + "print(\"external inductance=%.3f mH\" %(Le*1000))" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "external inductance=-2.000 mH\n" + ] + } + ], + "prompt_number": 12 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.15 Page No 414" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "R=10.0\n", + "L=0.015\n", + "T_a=L/R\n", + "f=1250.0\n", + "T=1.0/f\n", + "a=0.5\n", + "T_on=a*T\n", + "V_s=220.0\n", + "\n", + "#Calculations\n", + "I_mx=(V_s/R)*((1-math.exp(-T_on/T_a))/(1-math.exp(-T/T_a))) \n", + "I_mn=(V_s/R)*((math.exp(T_on/T_a)-1)/(math.exp(T/T_a)-1)) \n", + "dI=I_mx-I_mn \n", + "V_o=a*V_s\n", + "I_o=V_o/R \n", + "I_or=math.sqrt(I_mx**2+dI**2/3+I_mx*dI) \n", + "I_chr=math.sqrt(a)*I_or \n", + "\n", + "#Results\n", + "print(\"Max value of ripple current=%.2f A\" %dI)\n", + "print(\"Max value of load current=%.3f A\" %I_mx)\n", + "print(\"Min value of load current=%.2f A\" %I_mn)\n", + "print(\"Avg value of load current=%.2f A\" %I_o) \n", + "print(\"rms value of load current=%.2f A\" %I_or)\n", + "print(\"rms value of chopper current=%.2f A\" %I_chr)\n", + " #Answers have small variations from that in the book due to difference in the rounding off of digits." + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "Max value of ripple current=2.92 A\n", + "Max value of load current=12.458 A\n", + "Min value of load current=9.54 A\n", + "Avg value of load current=11.00 A\n", + "rms value of load current=13.94 A\n", + "rms value of chopper current=9.86 A\n" + ] + } + ], + "prompt_number": 14 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.17 Page No 417" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "L=0.0016\n", + "C=4*10**-6\n", + "\n", + "#Calculations\n", + "w=1/math.sqrt(L*C)\n", + "t=math.pi/w \n", + "\n", + "\n", + "#Results\n", + "print(\"time for which current flows=%.2f us\" %(t*10**6))" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "time for which current flows=251.33 us\n" + ] + } + ], + "prompt_number": 15 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.18, Page No 424" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "t_q=20.0*10**-6\n", + "dt=20.0*10**-6\n", + "\n", + "#Calculations\n", + "t_c=t_q+dt\n", + "I_0=60.0\n", + "V_s=60.0\n", + "C=t_c*I_0/V_s \n", + "\n", + "#Results \n", + "print(\"value of commutating capacitor=%.0f uF\" %(C*10**6))\n", + "\n", + "L1=(V_s/I_0)**2*C\n", + "L2=(2*t_c/math.pi)**2/C\n", + "if L1>L2 :\n", + " print(\"value of commutating inductor=%.0f uH\" %(L1*10**6))\n", + "else:\n", + " print(\"value of commutating inductor=%.0f uH\" %(L2*10**6))\n" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "value of commutating capacitor=40 uF\n", + "value of commutating inductor=40 uH\n" + ] + } + ], + "prompt_number": 19 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.19, Page No 424" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "t=100.0*10**-6\n", + "R=10.0\n", + "\n", + "#Calculations\n", + " #V_s*(1-2*math.exp(-t/(R*C)))=0\n", + "C=-t/(R*math.log(1.0/2)) \n", + "L=(4/9.0)*C*R**2 \n", + "L=(1.0/4)*C*R**2 \n", + "\n", + "#Results\n", + "print(\"Value of comutating component C=%.3f uF\" %(C*10**6))\n", + "print(\"max permissible current through SCR is 2.5 times load current\")\n", + "print(\"value of comutating component L=%.1f uH\" %(L*10**6))\n", + "print(\"max permissible current through SCR is 1.5 times peak diode current\")\n", + "print(\"value of comutating component L=%.2f uH\" %(L*10**6))" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "Value of comutating component C=14.427 uF\n", + "max permissible current through SCR is 2.5 times load current\n", + "value of comutating component L=360.7 uH\n", + "max permissible current through SCR is 1.5 times peak diode current\n", + "value of comutating component L=360.67 uH\n" + ] + } + ], + "prompt_number": 20 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.20, Page No 426" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "T_on=800.0*10**-6\n", + "V_s=220.0\n", + "I_o=80.0\n", + "C=50*10**-6\n", + "\n", + "#Calculations\n", + "T=T_on+2*V_s*C/I_o \n", + "L=20*10**-6\n", + "C=50*10**-6\n", + "i_T1=I_o+V_s*math.sqrt(C/L) \n", + "i_TA=I_o \n", + "t_c=C*V_s/I_o \n", + "t_c1=(math.pi/2)*math.sqrt(L*C) \n", + "t=150*10**-6\n", + "v_c=I_o*t/C-V_s \n", + "\n", + "#Results \n", + "print(\"effective on period=%.0f us\" %(T*10**6))\n", + "print(\"peak current through main thyristor=%.2f A\" %i_T1)\n", + "print(\"peak current through auxillery thyristor=%.0f A\" %i_TA)\n", + "print(\"turn off time for main thyristor=%.1f us\" %(t_c*10**6))\n", + "print(\"turn off time for auxillery thyristor=%.3f us\" %(t_c1*10**6))\n", + "print(\"total commutation interval=%.0f us\" %(2*t_c*10**6))\n", + "print(\"capacitor voltage=%.0f V\" %v_c)\n", + "print(\"time nedded to recharge the capacitor=%.0f us\" %(2*V_s*C/I_o*10**6))" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "for firing angle = 30deg\n", + "avg output voltage=232.509 V\n", + "for firing angle = 60deg\n", + "avg output voltage=133.65 V\n", + "avg current rating=12 A\n", + "rms current rating=20.785 A\n", + "PIV of SCR=565.7 V\n", + "power dissipated=16.8 W\n" + ] + } + ], + "prompt_number": 122 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.21, Page No 427" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "I_o=260.0\n", + "V_s=220.0\n", + "fos=2 #factor of safety\n", + "\n", + "#Calculations\n", + "t_off=18*10**-6\n", + "t_c=2*t_off\n", + "C=t_c*I_o/V_s \n", + "L=(V_s/(0.8*I_o))**2*C \n", + "f=400\n", + "a_mn=math.pi*f*math.sqrt(L*C)\n", + "V_omn=V_s*(a_mn+2*f*t_c) \n", + "V_omx=V_s \n", + "\n", + "#Results\n", + "print(\"Value of C=%.3f uF\" %(C*10**6))\n", + "print(\"value of L=%.3f uH\" %(L*10**6))\n", + "print(\"min value of o/p voltage=%.3f V\" %V_omn)\n", + "print(\"max value of o/p voltage=%.0f V\" %V_omx)" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "firing angle delay=47.461 deg\n", + "pf=0.646\n", + "firing angle delay=127.71 deg\n" + ] + } + ], + "prompt_number": "*" + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.22, Page No 434" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "x=2.0\n", + "t_q=30*10**-6\n", + "dt=30*10**-6\n", + "t_c=t_q+dt\n", + "V_s=230.0\n", + "I_o=200.0\n", + "\n", + "#Calculations\n", + "L=V_s*t_c/(x*I_o*(math.pi-2*math.asin(1/x))) \n", + "C=x*I_o*t_c/(V_s*(math.pi-2*math.asin(1/x))) \n", + "V_cp=V_s+I_o*math.sqrt(L/C) \n", + "I_cp=x*I_o \n", + "x=3\n", + "L=V_s*t_c/(x*I_o*(math.pi-2*math.asin(1/x))) \n", + "C=x*I_o*t_c/(V_s*(math.pi-2*math.asin(1/x))) \n", + "V_cp=V_s+I_o*math.sqrt(L/C) \n", + "I_cp=x*I_o \n", + "\n", + "#Results\n", + "print(\"value of commutating inductor=%.3f uH\" %(L*10**6))\n", + "print(\"value of commutating capacitor=%.3f uF\" %(C*10**6))\n", + "print(\"peak capacitor voltage=%.0f V\" %V_cp)\n", + "print(\"peak commutataing current=%.0f A\" %I_cp)\n", + "print(\"value of commutating inductor=%.3f uH\" %(L*10**6))\n", + "print(\"value of commutating capacitor=%.3f uF\" %(C*10**6))\n", + "print(\"peak capacitor voltage=%.2f V\" %V_cp)\n", + "print(\"peak commutataing current=%.0f A\" %I_cp)\n" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "value of commutating inductor=7.321 uH\n", + "value of commutating capacitor=49.822 uF\n", + "peak capacitor voltage=307 V\n", + "peak commutataing current=600 A\n", + "value of commutating inductor=7.321 uH\n", + "value of commutating capacitor=49.822 uF\n", + "peak capacitor voltage=306.67 V\n", + "peak commutataing current=600 A\n" + ] + } + ], + "prompt_number": 25 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.23, Page No 434" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variablesV_s=230\n", + "C=50*10**-6\n", + "L=20*10**-6\n", + "I_cp=V_s*math.sqrt(C/L)\n", + "I_o=200\n", + "x=I_cp/I_o\n", + "\n", + "#Calculations\n", + "t_c=(math.pi-2*math.asin(1/x))*math.sqrt(C*L) \n", + "th1=math.degrees(math.asin(1.0/x))\n", + "t=(5*math.pi/2-th1*math.pi/180)*math.sqrt(L*C)+C*V_s*(1-math.cos(math.radians(th1)))/I_o \n", + "t=(math.pi-th1*math.pi/180)*math.sqrt(L*C) \n", + "\n", + "#Results\n", + "print(\"turn off time of main thyristor=%.2f us\" %(t_c*10**6))\n", + "print(\"total commutation interval=%.3f us\" %(t*10**6))\n", + "print(\"turn off time of auxillery thyristor=%.3f us\" %(t*10**6))" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "turn off time of main thyristor=62.52 us\n", + "total commutation interval=80.931 us\n", + "turn off time of auxillery thyristor=80.931 us\n" + ] + } + ], + "prompt_number": 27 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.24, Page No 440" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "tc=0.006\n", + "R=10.0\n", + "L=R*tc\n", + "f=2000.0\n", + "\n", + "#Calculations\n", + "T=1/f\n", + "V_o=50.0\n", + "V_s=100.0\n", + "a=V_o/V_s\n", + "T_on=a*T\n", + "T_off=T-T_on\n", + "dI=V_o*T_off/L\n", + "I_o=V_o/R\n", + "I2=I_o+dI/2 \n", + "I1=I_o-dI/2 \n", + "\n", + "#Results\n", + "print(\"max value of load current=%.3f A\" %I2)\n", + "print(\"min value of load current=%.3f A\" %I1)\n" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "max value of load current=5.104 A\n", + "min value of load current=4.896 A\n" + ] + } + ], + "prompt_number": 28 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.27, Page No 443" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "I_a=30.0\n", + "r_a=.5\n", + "V_s=220.0\n", + "\n", + "#Calculations\n", + "a=I_a*r_a/V_s \n", + "a=1\n", + "k=.1 #V/rpm\n", + "N=(a*V_s-I_a*r_a)/k \n", + "\n", + "#Results\n", + "print(\"min value of duty cycle=%.3f\" %a)\n", + "print(\"min Value of speed control=%.0f rpm\" %0)\n", + "print(\"max value of duty cycle=%.0f\" %a)\n", + "print(\"max value of speed control=%.0f rpm\" %N)" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "min value of duty cycle=1.000\n", + "min Value of speed control=0 rpm\n", + "max value of duty cycle=1\n", + "max value of speed control=2050 rpm\n" + ] + } + ], + "prompt_number": 29 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.28, Page No 444" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variables\n", + "V_t=72.0\n", + "I_a=200.0\n", + "r_a=0.045\n", + "N=2500.0\n", + "\n", + "#Calculations\n", + "k=(V_t-I_a*r_a)/N\n", + "E_a=k*1000\n", + "L=.007\n", + "Rm=.045\n", + "Rb=0.065\n", + "R=Rm+Rb\n", + "T_a=L/R\n", + "I_mx=230\n", + "I_mn=180\n", + "T_on=-T_a*math.log(-((V_t-E_a)/R-I_mx)/((I_mn)-(V_t-E_a)/R))\n", + "R=Rm\n", + "T_a=L/R\n", + "T_off=-T_a*math.log(-((-E_a)/R-I_mn)/((I_mx)-(-E_a)/R))\n", + "T=T_on+T_off\n", + "f=1/T \n", + "a=T_on/T \n", + "\n", + "#Results\n", + "print(\"chopping freq=%.1f Hz\" %f) \n", + "print(\"duty cycle ratio=%.3f\" %a)\n" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "chopping freq=40.5 Hz\n", + "\n", + "duty cycle ratio=0.588\n" + ] + } + ], + "prompt_number": 30 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 7.29, Page No 445" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "import math\n", + "#initialisation of variablesI_mx=425\n", + "I_lt=180.0 #lower limit of current pulsation\n", + "I_mn=I_mx-I_lt\n", + "T_on=0.014\n", + "T_off=0.011\n", + "\n", + "#Calculations\n", + "T=T_on+T_off\n", + "T_a=.0635\n", + "a=T_on/T\n", + "V=(I_mx-I_mn*math.exp(-T_on/T_a))/(1-math.exp(-T_on/T_a))\n", + "a=.5\n", + "I_mn=(I_mx-V*(1-math.exp(-T_on/T_a)))/(math.exp(-T_on/T_a))\n", + "T=I_mx-I_mn \n", + "T=T_on/a\n", + "f=1/T \n", + "\n", + "#Results\n", + "print(\"higher limit of current pulsation=%.0f A\" %T)\n", + "print(\"chopping freq=%.3f Hz\" %f)\n", + "print(\"duty cycle ratio=%.2f\" %a)\n", + " #Answers have small variations from that in the book due to difference in the rounding off of digits." + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "higher limit of current pulsation=0 A\n", + "chopping freq=35.714 Hz\n", + "duty cycle ratio=0.50\n" + ] + } + ], + "prompt_number": 32 + } + ], + "metadata": {} + } + ] +} \ No newline at end of file -- cgit