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Vg=28 Vo=15 Ro=3- N+ H8 {) p5 x H0 M+ U
H=5/15 分壓! `* Z+ M) O; E! q% R8 @; l2 c! D
Vref=5. @7 R! H- O6 h8 V0 M/ U& `3 J8 F
% VRM
& t* _. C/ H5 s+ os = tf('s');" b9 X- d. i% u3 l0 s
% Input voltage Vin
( I4 c1 |) u: Y& Q U0 CVin=28
9 n s. n4 N9 u0 ?8 v. a% Output voltage Vo
/ b" Q0 P2 u' o; h" PVo=156 i' {4 H; k. }% C" d6 i
% LOAD R Z: r# M! [( K: F0 _: r
RL=3: Q3 d+ f4 G% r, f: Z
% PWM operating frequency Fsw; N H$ n7 P' n0 E% }; G; L
Fsw=100e3; n$ B' J% k3 C7 Y% Y
% PWM operating period Ts
% r: s0 j2 F0 y. sTs=1/Fsw
, W' F, c8 M1 D5 o& t" }3 R% [% duty cycle D" L* B2 z! F& Y0 B8 O( Z
D=Vo/Vin
- V( \" J' G. V4 `% Inductance L
, B" {( v6 R- Y2 v: X0 e& A l( l5 kL=50e-6
, `1 ^6 K0 R5 N+ i% Output capacitance
, L# g$ G" Z. F+ @2 r' nCo=500e-6. k4 i" L1 ]) a
%power stage Gvd 2 S$ u" y5 q, n
%Gvd=(Vin*((s*Co*RL*rc)+RL))/((s^2*L*Co*(RL+rc))+(s*(L+(Co*rc*rL)+Co*RL*(rc+rL)))+RL+rL)' x6 l a4 B9 D% @' e' W) n2 b
Gvd=(Vin*RL)/((s^2*L*Co*RL)+s*L+RL)
; ^( X- v! |8 x8 hfigure(1)
( F* C2 W1 ? s5 @5 Vmargin(Gvd)
, R4 u p+ F! H/ E: aF0=1/(2*pi*sqrt(L*Co))$ B, q$ U. Q& H9 {9 Q* h
%Fesr=1/(2*pi*Co*rc)
5 w4 q" v6 z4 u7 @: L8 ^) ?" I$ A, fFc=Fsw/20: c5 g! ~% U2 R3 g( r/ f. y
% 分壓比
/ e6 w1 s2 i) w- k+ q( `H=1/35 ^+ A; u8 x: ^2 Z$ }2 Y, w
% PWM Vm% p) a0 R h$ Y- q2 l
Vm=4( k9 I$ E9 m. p, D% _7 A
% uncompensation loop gain Tu0
! S9 d$ ^8 b% M1 |. D$ yTu0=H*Vin/Vm
# V" D/ a3 J( G/ p& J) X% 補償zero Fz
6 |7 S" `% V' n" z, E5 GFz=Fc*sqrt((1-sin (52*(pi/180)))/(1+sin (52*(pi/180))))
3 I* l, v1 ]' F; g% 補償pole Fp 4 Z `6 \6 ^/ z7 _
Fp=Fc*sqrt((1+sin (52*(pi/180)))/(1-sin (52*(pi/180))))
4 u. A% k0 f: LWz=2*pi*Fz
2 [4 e5 A0 R. {, [: W& h7 e, d1 iR1=2e3
5 h4 d' I0 i C5 c& WC1=1/(R1*Wz): {, U/ | D L6 D3 `( V# g( a
Wp=2*pi*Fp; c0 v, j( m/ f! W5 l8 s g
R3=R1/(Wp*R1*C1-1)
/ M- L2 u& P' u% ~% compensation gain Gc0
! _/ T( m6 A2 hGc0=(((Fc/F0)^2)/Tu0)*sqrt(Fz/Fp)2 U \2 q0 t7 O( n0 l) }1 D
R2=Gc0*(R1+R3)
/ G3 u$ l. w) m6 Q5 _4 o r% OPA gain:A;OPA open loop gain:A0 ; dominant pole ; compensator close feedback gain:Gcl 0 K3 i4 ?& L8 w* i# f$ A
A0=1
7 x$ E6 i% Y" g3 b! Op=10e3*2*pi* k9 g* |0 N& M: q N) H. h
A=A0*p/(s+p)
+ {3 _7 X$ C" H. wGc=(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)))
2 \* W. ~# p H z0 {figure(2)
" s* N! ^( F3 Y% ^- w; \bode(Gc,A)
2 u: T5 C/ ~& h) h& }9 n3 Q; I% total loop gain T
/ }2 [- e# A( }, hT=Tu0*Gc0*(1+s/Wz)*RL/((1+s/Wp)*((s^2*L*Co*RL)+s*L+RL))
8 f) b4 x3 ]2 v. O. b! c% total colse loop gain Gcl
4 O7 v3 D9 j: O6 e) CGcl=(Gc*(1/Vm)*Gvd)/(1+Gc*(1/Vm)*Gvd*H)+ }* F; r9 g! h3 W7 w
figure(3)1 E! v3 w" |& }' c4 p# Z* j- e
bode(Gvd,Gcl,Gc,A,T) |
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