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Vg=28 Vo=15 Ro=3
# h8 c4 ?- x( \# M! |H=5/15 分壓
( M u& E" R9 Z# WVref=5) ]/ F1 w) D5 g O5 L" [
% VRM 9 }% q8 y. |" S! B
s = tf('s');
5 _6 R, x6 G2 x% Input voltage Vin
7 _ Q6 C- W5 }8 \* z y( a" DVin=28: l% [) v! N! l" H5 Y3 K
% Output voltage Vo* J+ V, S" F- B: J6 D2 @. f
Vo=15
* t0 P2 H0 ?0 e5 ^% e) h5 d% LOAD R/ o1 S! T7 j! F) l! ^$ J1 H
RL=3
/ r& a, R4 c( {( _) G$ Z% PWM operating frequency Fsw3 c8 I5 N' P$ t$ ]" b; {- y, s$ X
Fsw=100e3; i+ x) j3 z3 X$ D P+ w
% PWM operating period Ts0 g2 I; n* B8 j# ?# J
Ts=1/Fsw
3 s0 X) s8 B$ x3 ?- B; m% duty cycle D
- G6 H$ V( r6 U! X3 R2 jD=Vo/Vin8 K. m U( P% {+ g( x
% Inductance L
4 T; t% L" \( \3 n+ j: JL=50e-63 I& i: h2 b% p" d
% Output capacitance8 ^4 h( w, d2 c& l- ]# L
Co=500e-6
) _/ r2 ]. ^$ j, [& g9 w* C%power stage Gvd . d/ z3 }2 _% V0 ?
%Gvd=(Vin*((s*Co*RL*rc)+RL))/((s^2*L*Co*(RL+rc))+(s*(L+(Co*rc*rL)+Co*RL*(rc+rL)))+RL+rL)
; o8 S$ G$ h; ]- @( uGvd=(Vin*RL)/((s^2*L*Co*RL)+s*L+RL)
" F3 q2 |9 c7 T( Tfigure(1)1 x" {! E0 y2 |% j' ?( H& ^) Z1 u
margin(Gvd)
, b7 {! f7 W% b& d g+ K8 PF0=1/(2*pi*sqrt(L*Co))
! \5 u$ c( t5 x3 m%Fesr=1/(2*pi*Co*rc)2 e+ i- b$ }/ b' B
Fc=Fsw/20
; H8 P2 W- o( `/ }) d+ Q# c% 分壓比* x3 k; h$ L7 f
H=1/3# f; f5 K0 l, J3 s
% PWM Vm
( s& p; h7 |5 n0 ?1 aVm=4
- W9 a# ]( M# c R% uncompensation loop gain Tu06 y8 o! v9 s+ A+ `* Y3 H
Tu0=H*Vin/Vm
, ^ R) G, } S, s% 補償zero Fz ( g/ M" d2 z: [9 g$ S
Fz=Fc*sqrt((1-sin (52*(pi/180)))/(1+sin (52*(pi/180))))8 T& x" m+ m( H0 O$ X; E
% 補償pole Fp 2 M" `+ V9 W. O9 p- k! q* x2 v& ?# n
Fp=Fc*sqrt((1+sin (52*(pi/180)))/(1-sin (52*(pi/180))))$ m, t4 j% b! E$ r* P, ]
Wz=2*pi*Fz
3 i+ Q' `( Y. XR1=2e3
3 v D. T9 B/ d3 _+ {! e4 lC1=1/(R1*Wz)
: V7 Y: O% B& q( y$ FWp=2*pi*Fp6 y; o% o; q& K# B! u9 A
R3=R1/(Wp*R1*C1-1)7 Y; {: `& J; `
% compensation gain Gc0 I; l* N7 M! B5 i3 P, d' V: @
Gc0=(((Fc/F0)^2)/Tu0)*sqrt(Fz/Fp)+ A7 U, G% R c; Z Y
R2=Gc0*(R1+R3)( m4 B2 X4 [1 v5 i
% OPA gain:A;OPA open loop gain:A0 ; dominant pole ; compensator close feedback gain:Gcl " R9 m( G" o8 `* `- u4 n" d
A0=17 P5 b5 H0 b8 `3 h# y' v% w$ k2 Z' F1 C
p=10e3*2*pi
% q6 X* C3 l k0 W' XA=A0*p/(s+p)" F( u6 e( }& w! G, v! K7 p4 P, e
Gc=(A0*p*R2+s*A0*p*R1*R2*C1)/(s^2*(R1*R2*C1+C1*R1*R3)+s*(A0*p*R1*R3*C1+p*R1*R3*C1+p*R1*R2*C1+R1+R2+R3)+(A0*p*R1+A0*p*R3+p*(R1+R3+R2)))* |$ _# p/ D5 ?% m2 r& t. O
figure(2)7 |' {9 J8 Q, X$ d H7 L
bode(Gc,A)4 O( |0 m& g3 W# O F6 j) A
% total loop gain T: n* I1 u* t3 Q" c
T=Tu0*Gc0*(1+s/Wz)*RL/((1+s/Wp)*((s^2*L*Co*RL)+s*L+RL))
3 p: h3 {8 Y* }6 c% total colse loop gain Gcl
6 }+ g# t$ A: a" m# T4 MGcl=(Gc*(1/Vm)*Gvd)/(1+Gc*(1/Vm)*Gvd*H)
. k+ P3 T" \9 f- g3 }figure(3)3 v V$ c7 R( Q; p
bode(Gvd,Gcl,Gc,A,T) |
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