Prof R T KennedyPOWER ELECTRONICS 21 EET 423 POWER ELECTRONICS -2

Prof R T KennedyPOWER ELECTRONICS 22 BUCK CONVERTER CIRCUIT CURRENTS I fwd I ds E i n I i n ILIL I ds ICIC I fwd C R L ILIL I out a b V out

Prof R T KennedyPOWER ELECTRONICS 23 BUCK CONVERTER CIRCUIT VOLTAGES E i n V out V ds a b V L,a-b C R L V fwd

Prof R T KennedyPOWER ELECTRONICS 24 SUB INTERVAL EQUIVALENT CIRCUITS V ds = 0 a b V L,a-b = E in -V out E i n C R V out L MOSFET ON RECTIFIER OFF V fwd = -E in r ds,on

Prof R T KennedyPOWER ELECTRONICS 25 SUB INTERVAL EQUIVALENT CIRCUITS E i n C R a b V out V fwd = 0 V ds = E in MOSFET OFF RECTIFIER ON L a b V L,a-b = -V out a b

Prof R T KennedyPOWER ELECTRONICS 26 E in =V ds +(- V fwd ) V L + V out = -V fwd E in VLVL V out V fwd V ds 0 V gs

Prof R T KennedyPOWER ELECTRONICS 27 E in = V ds + (-V fwd ) E in VLVL V out V fwd V ds 0 V gs - V fwd

Prof R T KennedyPOWER ELECTRONICS 28 SMPS OPERATION QUANTIZED POWER/ENERGY TRANSFER VOLTAGE REGULATION

Prof R T KennedyPOWER ELECTRONICS 29 VOLTAGE TRANSFER FUNCTION ANALYSIS ENERGY BALANCE ENERGY BALANCE POWER BALANCE POWER BALANCE VOLT-TIME INTEGRAL VOLT-TIME INTEGRAL

Prof R T KennedyPOWER ELECTRONICS 210 ‘IDEAL’ BUCK ANALYSIS CCM ENERGY BALANCE APPROACH INDUCTOR CURRENT I L,M I L,m I L,av = I out 0 t

Prof R T KennedyPOWER ELECTRONICS 211 SUB INTERVAL -1: MOSFET ON E i n C R L OFF a b ON ENERGY STORED INPUT ENERGY LOAD ENERGY from source

Prof R T KennedyPOWER ELECTRONICS 212 SUB INTERVAL -2: RECTIFIER ON E i n C R L ON a b OFF ENERGY Discharge NO INPUT ENERGY LOAD ENERGY from inductor

Prof R T KennedyPOWER ELECTRONICS 213 D sw E in V out

Prof R T KennedyPOWER ELECTRONICS 214 ‘IDEAL’ BUCK ANALYSIS CCM POWER BALANCE APPROACH INPUT CURRENT = MOSFET CURRENT I in,av = I ds,av I L,m I L,M I out 0 D sw T D fwd T I in t

Prof R T KennedyPOWER ELECTRONICS 215 FARADAY’S VOLT-TIME INTEGRAL INDUCTOR VOLTAGE V1V1 t1t1 0 INDUCTOR CURRENT t2t2 V2V2 0 t t I m I M T current start and finish at same value EQUAL AREAS

Prof R T KennedyPOWER ELECTRONICS 216 ‘IDEAL’ BUCK ANALYSIS CCM VOLT-TIME INTEGRAL APPROACH INDUCTOR VOLTAGE D sw T D fwd T 0 ILIL VLVL 0 E in -V out -V out t area B area A

Prof R T KennedyPOWER ELECTRONICS 217 ‘IDEAL’ BUCK ANALYSIS CCM VOLT-TIME INTEGRAL APPROACH INDUCTOR VOLTAGE

Prof R T KennedyPOWER ELECTRONICS 218 ‘ideal’ BUCK CONVERTER CCM voltage & current waveforms refer to msw notelet refer to msw notelet

Prof R T KennedyPOWER ELECTRONICS 219 V out 0 0 D sw TD fwd T D fwd = 1-D sw V gs I out IcIc ILIL I ds I fwd E in V ds V fwd VLVL V out E i n R I out IC IC L C I ds IL IL V ds I out I fwd V fwd V gs f sw VL VL

Prof R T KennedyPOWER ELECTRONICS 220 INDUCTOR CURRENT WAVEFORMS CCM or DCM operational mode CCM or DCM operational mode component current stress component current stress capacitor ripple current capacitor ripple current output voltage ripple output voltage ripple converter efficiency converter efficiency closed loop regulation performance closed loop regulation performance

Prof R T KennedyPOWER ELECTRONICS 221 INDUCTOR CURRENT v INDUCTANCE REDUCTION in L D sw TD fwd T 0 0 I out E in - V out -V out VLVL ILIL t

Prof R T KennedyPOWER ELECTRONICS 222 INDUCTOR CURRENT v INDUCTANCE REDUCTION in L D sw TD fwd T 0 0 I out E in -V out -V out VLVL ILIL t increased I sw,max I fwd,max I C,ripple V out,ripple

Prof R T KennedyPOWER ELECTRONICS 223 INDUCTOR CURRENT

Prof R T KennedyPOWER ELECTRONICS 224 INDUCTOR CURRENT 0 ILIL t I out D sw = 0.2 D sw = 0.5 D sw = 0.8 D sw > 0.5 D sw < 0.5 D sw = 0.5

Prof R T KennedyPOWER ELECTRONICS 225 INDUCTOR CURRENT 0 ILIL t UPSLOPE DOWNSLOPE

Prof R T KennedyPOWER ELECTRONICS 226 INDUCTOR PEAK-PEAK RIPPLE CURRENT

Prof R T KennedyPOWER ELECTRONICS 227 ILIL ILIL ILIL t t t

Prof R T KennedyPOWER ELECTRONICS 228 ILIL ILIL ILIL t t t 

Prof R T KennedyPOWER ELECTRONICS 229 ILIL ILIL ILIL t t t 

Prof R T KennedyPOWER ELECTRONICS 230 ‘IDEAL’ BUCK CCM DEVICE CURRENT

Prof R T KennedyPOWER ELECTRONICS 231 ‘IDEAL’ BUCK CCM DEVICE CURRENT

Prof R T KennedyPOWER ELECTRONICS 232 ‘IDEAL’ BUCK CCM TRANSISTOR CURRENT

Prof R T KennedyPOWER ELECTRONICS 233 ‘IDEAL’ BUCK CCM RECTIFIER CURRENT

Prof R T KennedyPOWER ELECTRONICS 234 OUTPUT EFFECTS E i n C L V out = 0 s/c I in t 0

Prof R T KennedyPOWER ELECTRONICS 235 OUTPUT EFFECTS E i n C L V out  E in o/c

Prof R T KennedyPOWER ELECTRONICS 236 POWER - UP EFFECT E i n C R V out V c = 0 L

Prof R T KennedyPOWER ELECTRONICS 237 POWER - DOWN EFFECT E i n C R V out L

Prof R T KennedyPOWER ELECTRONICS 238 CCM-DCM BOUNDARY

Prof R T KennedyPOWER ELECTRONICS 239 CCM-DCM BOUNDARY boundary

Prof R T KennedyPOWER ELECTRONICS 240 CCM-DCM BOUNDARY boundary CCM DCM

Prof R T KennedyPOWER ELECTRONICS 241 CCM / DCM determined by R CCM-DCM BOUNDARY L D sw f sw constant to ensure a desired CCM does not transfer to DCM specify a minimum load current (maximum R) avoid open circuit operation CCM DCM INCREASE R ‘light loading’

Prof R T KennedyPOWER ELECTRONICS 242 CCM / DCM determined by L CCM-DCM BOUNDARY R D sw f sw constant to ensure a desired CCM does not transfer to DCM design for CMM at lowest inductance including  L v  I CCM DCM DECREASE L

Prof R T KennedyPOWER ELECTRONICS 243 CCM / DCM determined by f sw CCM-DCM BOUNDARY R D sw f sw constant to ensure a desired CCM does not transfer to DCM design for CMM at lowest frequency CCM DCM DECREASE f sw

Prof R T KennedyPOWER ELECTRONICS 244 CCM / DCM determined by D sw CCM-DCM BOUNDARY L R f sw constant to ensure a desired CCM does not transfer to DCM design for CMM at lowest duty cycle CCM DCM DECREASE D sw

Prof R T KennedyPOWER ELECTRONICS 245 LINE & LOAD REGULATION DCM CCM

Prof R T KennedyPOWER ELECTRONICS 246 LINE & LOAD REGULATION DCM CCM