THE ELECTROTHERMAL ANALYSIS OF A SWITCHED MODE VOLTAGE REGULATOR Krzysztof Górecki and Janusz...
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Transcript of THE ELECTROTHERMAL ANALYSIS OF A SWITCHED MODE VOLTAGE REGULATOR Krzysztof Górecki and Janusz...
THE ELECTROTHERMAL THE ELECTROTHERMAL ANALYSIS OF A SWITCHED ANALYSIS OF A SWITCHED
MODE VOLTAGE REGULATORMODE VOLTAGE REGULATOR Krzysztof Górecki and Janusz ZarębskiKrzysztof Górecki and Janusz Zarębski
Department of Marine Electronics Department of Marine Electronics
Gdynia Maritime University, POLANDGdynia Maritime University, POLAND
D E P A R T M E N T
F MARINE ELECTRONIC
22
OutlineOutline
IntroductionIntroduction The electrothermal model of the PWM The electrothermal model of the PWM
controller (UC3842)controller (UC3842) The electrothermal The electrothermal SPICE hybrid SPICE hybrid modelmodelss
((diodediode, MOS , MOS transistortransistor)) Results of Results of investigations of SMPS investigations of SMPS ConclusionsConclusions
33
IntroductionIntroduction
SMPS
Dc-dc converter PWM controller
RLC elements Semiconductor devices
transistors diodes
44
Introduction (cont.)Introduction (cont.)
Selfheating – results from changing the electrical energy into the heat and non-ideal cooling conditions
Due to selfheating Internal temperatures of semiconductor
devices increase Characteristics and parameters values of SMPS
change Electrothermal analysis – analysis with
selfheating taken into account
55
In the paperIn the paper
The new electrothermal models (ETM) of: the current mode PWM controller the diode the MOS transistor
dedicated for electrothermal analysis of SMPS in SPICE
Measurements and calculations of nonisothermal characteristics of SMPS
Why the new models are needed? the literature models are complicated the time duration of calculations with these models is
unacceptable long
66
The ETM of the UC3842 controllerThe ETM of the UC3842 controller
[1] Zarębski J., Górecki K.: Microelectronics Reliability, Vol. 47, No. 7, 2007, pp. 1145-1152.
D11
V12
D10
OUT
VCC
Q1
Q2
ISUPE1
E2
Q
Q
Ct/Rt OSC
GOSC
EO1
V1
EO2
V2
V3
Rstan
Cstan
EERR EERR1
D1 D2 ED1R1
R2VX
ED2D3
ELIMEp1
Ep2
FF
S
REF
COMP
FB
Estan
IS
TRthn
Cth1 Cthn
Rth1
Gp VtaThe thermal
model
The power model
Tj
The electrical model
R
CEA
REA
V11
RQ1
RQ2
Vicq 1
Vicq 2
VOSC
EREF
OS
EA
AB
The modified version of the model from [1]
The changes in description of the error amplifier block
In the model all terminals of IC, selfheating, nonlinear characteristics of semiconductor devices are taken into account
77
The The ETMsETMs of the diode of the diode and the MOSFET and the MOSFET
• The general conceptionThe general conception
+ ++ +
• Only characteristics of the forward biased diode and switched-on transistor operating in SMPS are important
Electrothermal hybrid model
SPICEisothermal
built-in model
Controlled sources modelling the
influence of selfheating
Thermal model
88
The The ETMsETMs of the diode of the diode and the MOSFET and the MOSFET (cont.)(cont.)
0TTRSiE jRSRS 01 TTE ju iupth
0TTRDiE jRDDRD
0TTE juG
DDSth iup
0
0,5
1
1,5
2
2,5
3
3,5
4
0 0,1 0,2 0,3 0,4 0,5 0,6
u [V]
i [A
]
1N5822
0
2
4
6
8
10
0 0,25 0,5 0,75 1 1,25 1,5 1,75 2
uDS [V]
i D [
A]
IRF640
uGS = 12 VTa = 300 K
99
Results of calculations Results of calculations and measurementsand measurements
Transient analysis till the steady-stateTransient analysis till the steady-stateOne non-physical thermal time constant – to short the time of One non-physical thermal time constant – to short the time of calculationscalculations
COMP
VFB
ISENSE
RT/CT GND
OUT
VCC
VREFU
UC
384
2
1
2
3
4 5
6
7
8L
RoCo
D1
M1
RS
Vin
+Vcc
C1
D2
R2
R3
C3D3
CT
R4
Q1
RT
R5R6
R7
R8
C4
R10
R9
P1
P2
R11
C5
1
1
2
2
Vout
BOOST converter
1010
Results - opened feedback loopResults - opened feedback loop
The calculations resultsThe calculations results
The measurements resultsThe measurements results
0
5
10
15
20
25
30
35
0 1 2 3 4 5 6
VCOMP [V]
Vou
t [V
]
VISMAX = 1.2V
R0 = 49.66 W
Vin = 12.3 V
RS = 1.153 W VISMAX = 2.1 V
VISMAX = 0.31 V
BOOST - opened feedback loop
0
5
10
15
20
25
30
35
40
45
50
1 10 100 1000
R0 [W]
Vou
t [V
]
VFB = 3.06 V
Vin = 6 VVIS = 0.6 V
RS = 1.125 W
RS = 0.409 WBOOST - opened feedback loop
1111
Results - closed feedback loopResults - closed feedback loop
The calculations resultsThe calculations results
The measurements resultsThe measurements results
0
24
6
8
1012
14
1618
20
0 5 10 15 20
Vin [V]
Vou
t [V
]
BOOST -closed feedback loop
RS = 0.397 W
R0 = 9.46 W
R0 = 49.67 W
0
2
4
6
8
10
12
14
1 10 100 1000
R0 [W]
Vou
t [V
]
Vin = 5 V
RS = 1 W
RS = 0.397 W
BOOST - closed feedback loop
1212
ConclusionsConclusions The presented calculations and measurements results confirm the
correctness of the proposed by the authors electrothermal model of the controller UC3842 and the hybrid electrothermal models of the MOS transistor and of the diode.
The calculations and measurements results show the influence of both the input signals of the controller and the values of the boost converter elements on the output voltage.
The possibility of taking into account the phenomenon of selfheating enabled, among others, determining from the computer simulations the admissible values of load resistance and the regulator input voltage, at which the voltage regulator operates properly and the admissible temperature of its component elements is not exceeded.