一種安全可調的穩壓器設計

from math import sqrt

def checkEq(R11, R22, R23):
Rx=R11 – Ra/K12
if Rx != 0: print(“Err R11:”, Rx)

Rx=R22*R23/(R22+R23) – K21*(Rp+R11)
if Rx != 0:  print(“Err (2):”, Rx)

Rx=R11 – (R22*(Rp+R23)/(R22+Rp+R23) / K22)
if Rx != 0:  print(“Err (3):”, Rx)
return

def par(r1,r2): return(r1*r2/(r1+r2))

eo=eo12
R1 = R11
R2 = R1*((eo/Vref) -1)
R22 = R2*Rpot / (Rpot – R2)

eo=eo21   #5.1V
#R1 = R11 + R21*Rpot / (R21 + Rpot)
#R2 = R1*(eo/Vref -1)
#R23 = R2

#eo=eo22   #24V ??

#R1 = R11
#R2 = R23 + R22*Rpot / (R22 + Rpot)
#eo = Vref*(R2/R1 + 1)
#eo22 = eo

#Let  
K12 = eo12/Vref – 1
K21 = eo21/Vref – 1
K22 = eo22/Vref – 1
Rp = Rpot
Ra = par(Rp,R22)

w3=K22/K21
A=w3*(R22 – K21*Rp) – R22
B=w3*R22*(R22+Rp) – Rp*(w3*K21*(Rp+R22)-R22) – R22*R22
C=Rp*R22*(0-w3*K21*(R22+Rp)-R22)

Q=B*B – 4*A*C
#print(A, B, C, Q)
if Q<0: exit(” Exit: Q<0, try another values for R11, Rpot, or ranges”)

R23_1 = (0-B + sqrt(Q)) /2/A
R23_2 = (0-B – sqrt(Q)) /2/A
print(”   R23_1, R23_2=”, R23_1, R23_2)
# since R23 should be > 0:  
if R23_1>0:  R23=R23_1
elif R23_2>0:  R23=R23_2
else:  print(“Error: both R23_1, R23_2 are not positives”)

# recalc eoij for a coherence check
eo12=Vref*(par(Rp,R22)/R11 +1)
eo21=Vref*(par(R23,R22)/(Rp+R11) +1)
eo22=Vref*(par(R22,R23+Rp)/R11 +1)
# update
K12 = eo12/Vref – 1
K21 = eo21/Vref – 1
K22 = eo22/Vref – 1

print(“Fig2c:”, f” eo12={eo12:.2f}”, f” eo21={eo21:.2f}”, f” eo22={eo22:.2f}”)
print(“Fig2c:”, f” Rpot={Rpot:.1f}”, f” R11={R11:.1f}”, f” R22={R22:.1f}”, f” R23={R23:.1f}”)
checkEq(R11, R22, R23)

# since the solution we got may be very sensitive due to a possible presence of a singular point in its vicinity (i.e. a small deviation of a resistor’s value can have large impact on the voltage) – hence 2 conclusions follows:
# – tolerances of resistors R11, R22, R23 have to be not worse than 1%;
# – the solution above has to be considered as a preliminary one, so we’ll make it more precise by the following code:  
R23lim=100*R23
R23=R23/3
while R23 < R23lim:
eo21_x=Vref*(par(R23,R22)/(Rp+R11) +1)
eo22_x=Vref*(par(R22,R23+Rp)/R11 +1)
if eo21_x – eo21 > 0.2: break
if abs(eo22 – eo22_x) < 0.1: break    # if eo22-x – eo22 < 0.1: break
R23 += 10   # +10 Ohm
else:  exit(“full cycle”)  
print( f” eo21={eo21_x:.2f}”, f” eo22={eo22_x:.2f}”,  f” R23={R23:.1f}”)

#-end-of-code-