ti: Thit k cu trc iu khin b bin i Buck-Boost c thng s mch lc nh
di y: in p uin = 24V, in p uo = 15V. in cm L = 100H. T in C = 697F
v rc = 0,01. Tn s pht xung fx = 100kHz. Cng sut 100W.
Yu cu:Xy dng m hnh tn hiu trung bnh ca cc b bin i Boost.Thit k
cu trc iu khin cho b bin i trn theo 2 ch :a. iu khin in p.b. iu
khin dng in (iu khin dng in nh v iu khin dng in trung bnh). Kim
chng kt qu m hnh ha v thit k bng phn mm Matlab.
1. Xy dng m hnh tn hiu trung bnh ca cc b bin i Buck- Boost bng
phng php trung bnh khng gian trng thi.Xt m hnh b bin i Buck - Boost
trong 2 trng thi: khi van V ng (trng thi 1) v khi van V h (trng thi
2):S mch in b bin i Buck - Boost trong trng thi 1S mch in b bin i
Buck - Boost trong trng thi 2
S dng nh lut KV ta c h phng trnh m t s mch in ca b bin i Buck -
Boost trong trng thi 1: => => => Chuyn h trn v dng phng
trnh trng thi chun ha Vi , u , Suy ra ta c:
Tng t s dng nh lut KV ta c h phng trnh m t s mch in ca b bin i
Buck Boost trong trng thi 2:
=>
Chuyn h trn v dng phng trnh trng thi chun ha ta c:
M hnh trung bnh vi s tham gia ca h s iu ch d l:
Hay c vit di dng tng qut Trong :
Suy ra: im cn bng ca m hnh trn xc nh bng cch cho o hm bng khng v
cc i lng trng thi xc lp, ta c:
Do m hnh trn phi tuyn, c th s dng cc phng php thit k b iu khin
cho b bin i Buck-Boost, ta cn tuyn tnh ha n. Ta s s dng m hnh tn
hiu nh thay th m hnh trn.M hnh tn hiu nh ca b bin i DC/DC:
Trong :
Tnh ton theo cc gi tr cho: Ta c: Suy ra: 2. Thit k b iu khin in
p cho b bin i Buck Boost.S cu trc iu khin in p:
Ta c hm truyn gia in p u ra v h s iu ch l:
S dng Toolbox Symbolic Math trong Matlab tnh ta thu c hm truyn
Gvd c dng:
Kho st th Bode ca hm truyn trn: th Bode ca hm truyn t GvdTheo th
Bode, hm truyn i tng c tn s ct xp x 21,1kHz, d tr pha (Phase
Margin) l 40,60Ta s s dng b Dng b b PD. fc=800Hz (fcf0=371HzW1
=1658 -------> f1=264HzQ0=3,7Kt qu m phng
