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Vg=28 Vo=15 Ro=30 f. V( r+ ~% p: N
H=5/15 分壓( s2 m4 a% Y* V2 Q! M/ k- C
Vref=5
3 i+ z8 {0 D* K2 g8 h" H1 e. F% VRM ( s& B X9 s+ W- z
s = tf('s');& D D& r3 ^$ f! m9 X$ f# p3 N4 e
% Input voltage Vin . O1 h# h$ V8 G0 O+ _( F, J
Vin=28! z/ o: ?( w/ `/ W5 h: A
% Output voltage Vo2 w) U' D3 E9 d, d+ O: \3 O% v
Vo=15, ?8 r2 K( V7 v0 c
% LOAD R
% f8 o9 L: ^. U0 J4 gRL=3* S6 F: D' K+ l j& N Z, [& U
% PWM operating frequency Fsw3 H: n$ q9 ~' C( h& f; V
Fsw=100e3
: {! f# z6 {. D, J2 R% PWM operating period Ts, ?, `7 v3 x& \1 h( f
Ts=1/Fsw3 @; H+ `% j* b! L, m. I
% duty cycle D& R* l$ ] c7 ^. m& s
D=Vo/Vin
, j2 f( E/ P3 o3 _# f% Inductance L
( A8 q4 _( T: j3 x. tL=50e-6: S& z8 b* a. Y" ?& t
% Output capacitance m- j2 D3 S' A$ A! l8 ~
Co=500e-6
3 m, Q. M0 }6 V- h, x* \3 Q' U%power stage Gvd & |# _2 |& {, V) C z e5 ~
%Gvd=(Vin*((s*Co*RL*rc)+RL))/((s^2*L*Co*(RL+rc))+(s*(L+(Co*rc*rL)+Co*RL*(rc+rL)))+RL+rL)
* ?& u o9 A; s$ CGvd=(Vin*RL)/((s^2*L*Co*RL)+s*L+RL)
Y5 x& S: ~( X: p' h% B; N& Tfigure(1)( ?* U. |- ?$ D5 S
margin(Gvd)) G2 {1 \ ^- n: R
F0=1/(2*pi*sqrt(L*Co))
0 _ A8 S, |3 p) h%Fesr=1/(2*pi*Co*rc)
1 g% v' _7 Z2 iFc=Fsw/20; _7 b k) b$ [' d* `+ `2 Z- {
% 分壓比
/ H* V4 g3 o3 F8 [/ V. @6 lH=1/3
& [/ G! D1 w8 _+ z% PWM Vm+ T9 G; h N- v I
Vm=43 @# [ K; h. @/ \" c8 S9 r
% uncompensation loop gain Tu05 }5 n7 C) M* n, _+ n
Tu0=H*Vin/Vm3 u2 p/ q% @' \; ~
% 補償zero Fz
0 ^6 W4 X L: S6 f* C0 o- y0 Z4 jFz=Fc*sqrt((1-sin (52*(pi/180)))/(1+sin (52*(pi/180))))
9 \8 M% i" ~+ O) I$ r- f, {" w# P' l! W% 補償pole Fp
: ]( Y1 b0 ?% H7 k! [0 J5 U2 qFp=Fc*sqrt((1+sin (52*(pi/180)))/(1-sin (52*(pi/180))))
! _, r. {8 d* }" y5 UWz=2*pi*Fz/ h' w9 ]3 L( A8 m
R1=2e38 e6 O7 c( z K, J7 p7 ]+ u
C1=1/(R1*Wz)
' V, W$ { B4 l# a# PWp=2*pi*Fp6 K0 \3 n) `) V5 @
R3=R1/(Wp*R1*C1-1)
5 N9 e* R: E9 }9 x( ?' ?# G% compensation gain Gc0
# [4 }3 u- F4 B1 YGc0=(((Fc/F0)^2)/Tu0)*sqrt(Fz/Fp)% a; a& Y! Z% }7 \* g; l; p- h6 F
R2=Gc0*(R1+R3)
, y* n; Y- s1 Q: Y! q- S$ y: z7 e0 ^% OPA gain:A;OPA open loop gain:A0 ; dominant pole ; compensator close feedback gain:Gcl ! H/ }7 {1 V$ S# q) A4 z
A0=18 Y/ P8 K8 l# A, c+ o
p=10e3*2*pi
) F2 p3 y, W I2 I# sA=A0*p/(s+p)* a( O# `2 F9 J: G& {
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)))
/ S5 k+ I" h6 Qfigure(2)
2 q- J) N/ a; W$ S# B7 Gbode(Gc,A)
# [+ G- ^8 k8 F% total loop gain T
( z# S' c+ ]% H, g) Z) u+ L! {T=Tu0*Gc0*(1+s/Wz)*RL/((1+s/Wp)*((s^2*L*Co*RL)+s*L+RL))! I8 \& L s o9 j( f m; Y. |
% total colse loop gain Gcl
$ Q( W8 T2 p' A% jGcl=(Gc*(1/Vm)*Gvd)/(1+Gc*(1/Vm)*Gvd*H)! M% w g! v$ ]. P0 ?; v% s a
figure(3)
6 Z" t# K5 f. G8 @0 Y% Obode(Gvd,Gcl,Gc,A,T) |
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