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Vg=28 Vo=15 Ro=39 `& r! }2 e) A, Z0 E, k8 y1 y
H=5/15 分壓. q' P. S' k9 S( x7 c
Vref=54 V) Y$ L+ M1 q4 Q4 V
% VRM
2 R6 o2 Q" l6 @+ _4 F/ `9 Xs = tf('s');
$ N7 B3 g$ m8 b: Y" P% Input voltage Vin 7 I3 a. y$ L- |6 h, p
Vin=28
( u5 ?. D8 I) t$ _* Y" ~4 A% Output voltage Vo+ J/ U+ o' j" y6 J- D
Vo=15
& h' |: _" y$ e* T& A% LOAD R( s! U9 J. [7 e0 F9 Y/ B
RL=30 z O1 O( k; ^+ M5 c8 w
% PWM operating frequency Fsw
7 D6 Q. z! e$ w) [- V2 t% uFsw=100e3
6 x l: O9 n* x; ?% PWM operating period Ts. y2 ]' s, R J! y: h
Ts=1/Fsw
/ {/ c" Q% x: O% duty cycle D
; ]$ | F5 v+ D% h: sD=Vo/Vin& G: B& N8 O" D6 O2 q' x* O
% Inductance L& _& y7 ?+ u( [3 h
L=50e-61 b) z% U9 ?" w! ?+ e7 w
% Output capacitance
% D0 m* o2 M5 u# R8 R' bCo=500e-6) W0 }/ [2 a( j+ k( K! f1 f
%power stage Gvd
( F1 n& u: m* T%Gvd=(Vin*((s*Co*RL*rc)+RL))/((s^2*L*Co*(RL+rc))+(s*(L+(Co*rc*rL)+Co*RL*(rc+rL)))+RL+rL)& g1 Y$ O6 S- O6 X
Gvd=(Vin*RL)/((s^2*L*Co*RL)+s*L+RL)3 c* d* f& }4 Y3 {7 q2 w- |* s+ T
figure(1)
/ o+ P: |4 s( o1 gmargin(Gvd)3 t# [9 s9 k2 D& t8 v
F0=1/(2*pi*sqrt(L*Co)): R8 y% R% \ T0 ^: O" T1 ]
%Fesr=1/(2*pi*Co*rc)" K ~: A3 F4 Y. E3 ]
Fc=Fsw/20
3 H( P1 e; |5 S1 B2 v8 W: z% 分壓比
% C' L1 t$ o @" h0 tH=1/3
$ {/ w" J+ v a) l% PWM Vm5 y2 c+ {* i9 l+ d, C5 p
Vm=4+ _+ ^1 }5 [; y6 q+ d% H# T
% uncompensation loop gain Tu0! c8 e4 {! I( l1 C' h" A: @
Tu0=H*Vin/Vm9 f. S; i8 J: {, e$ P
% 補償zero Fz 0 s! }' K- u% e* w6 O$ {9 Z
Fz=Fc*sqrt((1-sin (52*(pi/180)))/(1+sin (52*(pi/180))))& b. \7 U7 u! L
% 補償pole Fp # s! _) _' L& E- y) g
Fp=Fc*sqrt((1+sin (52*(pi/180)))/(1-sin (52*(pi/180))))
0 c/ p! y8 X% k- CWz=2*pi*Fz
: b$ @: y& U# a- j7 h. ^4 pR1=2e3
" l9 o1 J+ c9 |0 D2 t9 e2 R8 wC1=1/(R1*Wz)
; J# U% u1 a X! ?- fWp=2*pi*Fp
8 Y! |6 D4 L; L( E: G3 BR3=R1/(Wp*R1*C1-1)
3 L/ ~, C+ \7 R& \, O, y, C% compensation gain Gc0
X% H5 E8 l6 n: n3 P5 z( m" iGc0=(((Fc/F0)^2)/Tu0)*sqrt(Fz/Fp); g% ]! w1 ~$ Z
R2=Gc0*(R1+R3)! x T* F0 r6 t" |% ]
% OPA gain:A;OPA open loop gain:A0 ; dominant pole ; compensator close feedback gain:Gcl 2 ~0 `& i1 y e7 N* G/ t
A0=1
& Z- |7 `6 X9 u( i, V# [) U+ |. [ Op=10e3*2*pi7 B8 Q! M& w2 t0 g" _
A=A0*p/(s+p)0 q$ }6 Y* t3 n2 u- g& Y
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)))
; n, A& c4 R' U& M, Nfigure(2)! K: O# t* q6 N5 l& f7 j
bode(Gc,A)
) ?) @! }$ i4 c) T% total loop gain T
* _# O; F' w/ M0 H+ I4 |9 z# g3 @T=Tu0*Gc0*(1+s/Wz)*RL/((1+s/Wp)*((s^2*L*Co*RL)+s*L+RL))5 V: F- l' ^. x2 F2 S* H1 e" N4 t
% total colse loop gain Gcl
& [' ~; L1 Q; [, X$ { @# DGcl=(Gc*(1/Vm)*Gvd)/(1+Gc*(1/Vm)*Gvd*H)
- v$ z( r/ V5 Y& x5 J2 Bfigure(3)
* X3 T) m) n8 Ubode(Gvd,Gcl,Gc,A,T) |
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