Induction

%Design a 2.2KW, 400v, 3-phase, 50Hz, 1500 synchronous rpm, squirrel cage %induction motor. The machine is to be started by a star delta starter. The %efficiency is 0.8 and power factor is 0.825 at full load. %MAIN DIAMENSION disp('***************Main Diamension****************') n=input('Enter synchronous speed in rps:'); f = 50; p = 2*f/n Bav = 0.44; ac = 21000; Kw = 0.955; disp('Output coefficient:') Co = 11*Kw*Bav*ac/10^3 P= input('power handling capacity of motor in KW:'); eff = 0.8; pf = 0.825; disp('KVA input:') Q = P/(eff*pf) D = (Q/(1.18*Co*n))^(1/3) L = 1.18*D t = L/1.5 disp('Net iron length:') Li = 0.9*L

%frequency in Hz %No of poles

%efficiency %power factor

%Length of core

%STATOR DESIGN %winding disp('********************STATOR DESIGN******************') Es = input('Stator voltage per phase:'); disp('Flux per pole:') phi = Bav*t*L disp('Stator turns per phase:') Ts = Es/(4.44*f*phi*Kw) qs = 2; %slots per pole per phase Ss = qs*p*3 %Total stator slots Yss = pi*D*10^3/Ss %Stator slot pitch Total_stator_conductors = 6*Ts Zss = Total_stator_conductors/Ss %Stator conductors per slot Cs = Ss/4 %Coil span theta = pi/6 %Angle of chording Kp = cos(theta/2) Kd = sin(theta)/(2*sin(theta/2)) disp('Stator winding factor:') Kws = Kd*Kp %conductor size

disp('stator current per phase:') Is = P*10^3/(3*Es*eff*pf) Il = Is*sqrt(3) %stator line current Js = 4; %Current density As = Is/Js %Area of stator conductor req d = 0.95; as = pi/4*0.95^2 %Area of stator conductor used js = Is/as %Current density for stator conductors d1 = 1.041; %Slot diamension spreq = Zss*as Aslot = spreq/0.4 %space factor = 0.4 Wts_min = phi/(1.7*(Ss/p)*Li) %Minimum width of stator teeth Wts = 6; h=17; dss = h+4 %depth of slot Lmts = 2*L+2.3*t+Ss disp('Stator teeth') Flux_density = phi/((Ss/p)*Wts*Li) disp('Stator core') Flux = phi/2 Acs = Flux/1.2 %Assumed Flux_density = 1.2 dcsi = Acs/Li; dcs = 17; Bcs = (dcsi/dcs)*1.2 disp('Outside diameter of stator laminations') Do = 1000*D+2*dss+2*dcs %Rotor Design disp('********************Rotor Design********************') lgi= 0.2+ 2*sqrt(D*L) lg=0.3; %length of air-gap Dr = (D*1000 - 2*lg) %Diameter of rotor Sr = 22; %No of rotor slots Ysr = pi*Dr/Sr %Rotor slot pitch at air-gap ms = 3; disp('Rotor bar current') Ib = 2*ms*Kws*Ts*Is*pf/Sr jb = 6; abi = Ib/jb ab=44.6; Wsr = 6.8; Wdr = 9.3; Slot_pitch = pi*(Dr-2*Wdr)/Sr Wt = Slot_pitch-Wsr

Flux_rot_teeth = phi*10^3/((Sr/p)*Li*Wt) Lb = 1000*L+2*15+10 rho = 0.021; rb = rho*Lb/(ab*10^3) copper_loss = Sr*Ib^2*rb %end rings disp('Ring current') Irg = Sr*Ib/(pi*p) je = 6; ae = Irg/je de = 10; tc = 8; ae = de*tc; Dorg = Dr - 2*Wdr Dirg = Dorg - 2*de De = (Dorg+Dirg)/(2*10^3) %Mean diameter or end ring re = rho*pi*De/ae Copper_loss_ring = 2*Irg^2*re Total_copper_loss = Copper_loss_ring+copper_loss s=Total_copper_loss/(Total_copper_loss+P*10^3)*100 dcr = 17; Bcr = 1.185; Di = Dr - 2*Wdr - 2*dcr %No load current %1.Airgap disp('*************Magnetising current****************') disp('Airgap') Wo1 = 2; gap = 0.3; ratio1 = Wo1/gap Kcs1 = 0.68; %Carter's coeff for ratio 6.66 Kgss = Yss/(Yss - Kcs1*Wo1) Wo2 = 1.5; ratio2 = Wo2/gap Kcs2 = 0.6; %Carter's coeff for ratio 5 Kgsr = Ysr/(Ysr- Kcs2*Wo2) Kgs = Kgss*Kgsr Kgd =1; Kg = Kgs*Kgd Ag = pi*D*L/4 Bg6 = 1.36*Bav lge = Kgs*lg ATg = 8*10^5*Bg6*Kg*lg/10^3

%2.Stator tee th disp('stator teeth') Atp = Ss*Wts*Li/p Bts = 1.12; Bts6 = 1.36*Bts at_ts = 1200; mmf_req = at_ts*dss/10^3 %3.stator co re disp('stator core') Acs = Li*dcs Bcs = 1.185; lcs = pi*(D*1000+2*dss+dcs)/(3*p*1000) at_cs = 280; ATcs = 289*lcs %4.Rotor teeth disp('Rotor teeth') Wts3 = pi*(Dr-4*Wdr/3)/Sr - Wsr Atr = (Sr/p)*Wts3*Li/10^3 Btr3 = 1.16; Btr6 = 1.36*Btr3 a_tr = 2000; Atr = a_tr*Wdr/10^3 %5.Rotor core disp('Rotor core') Acr = Li*dcr/10^3 at_sr = 280; lcr = 18/10^3 ATcr = at_sr*lcr AT6 = ATg+ mmf_req + ATcs + Atr + ATcr Im = 0.427*p*AT6/(Kws*Ts) %Los s compon ent disp('Iron loss in stator teeth') Vst = 0.34/10^3; Wst = Vst*7.6*10^3 Max_flux = pi*Bts/2 Iron_loss1 = 11.5*Wst disp('Iron loss in stator core') Vsc = 0.985/10^3; Wsc = Vsc*7.6*10^3 Iron_loss2 = Wsc*4.9 Total_iron_loss = 2*(Iron_loss1+Iron_loss2)

%Friction & Windage Loss disp('Friction & Windage loss') Floss = 1.5*P*10^3/10^2 Total_noload_loss = Total_iron_loss+Floss Il = Total_noload_loss/(3*Es) Io = sqrt(Im^2+Il^2) percent_full_load_current = Io/Is*100 NL_pf = Il/Io %Short circuit current LAMss = 19.7/10^7; LAMsr = 15.7/10^7; LAMs =LAMss+LAMsr xs = 8*pi*f*Ts^2*L*LAMs/(p*qs) LoMo = 1.73/10^7; xo = 8*pi*f*Ts^2*LoMo/(p*qs) Xm = Es/Im qr = Sr/(3*p) xz = (1/(qs^2)+1/(qr^2))*5*Xm/(6*ms^2) Xs = xs+xo+xz rs = rho*Ts*Kcs1/as Total_stator_copper_loss = 3*Is^2*rs rr = Total_copper_loss/(3*Is^2*pf^2) Rs = rs+rr Zs = sqrt(Xs^2+Rs^2) Isc = Es/Zs sc_pf = Rs/Zs Total_lossfull_load=Total_stator_copper_loss+Total_copper_loss+Total_iron_loss+Floss

input = Total_lossfull_load+P*1000 eff_full_load = P*10^3/input*100 %END