01296332
TRANSCRIPT
DESIGN AND ANALYSIS OF FUZZY CONTROLLERS FOR DC-DC CONVERTERS Ahmed Rubaai Mohamed F Chouikha
Electrical amp Computer Engineering Department Howard University
2300 6h Street Northwest Washington DC 20059 USA
aruhaaiGilhowardedu
Abstract - A successful implementation of fuzzy controllers for DC-DC converters is presented in this paper Two different fuzzy logic control topologies are developed and implemented using different types of DC-DC converters such as the buck the boost the buck-boost and the sepic converters Issues of sudden changes in the load or parametric uncertainties control and communication interface among many other issues are discussed and presented The fundamentals governing the design control and performance of the DC-DC converters are also illustrated Properties of the proposed controllers are 1) robustness around the operating point 2 ) good performance of transient responses under varying loading conditions andor input voltage and 3) invariant dynamic performance in the presence of varying operating conditions Simulation results have been obtained using appropriate scaling factors associated with the input variables of the fuzzy controller
INTRODUCTION DC-DC switching converters are a traditional benchmark for testing nonlinear controllers due to their inherent nonlinear characteristics After the pioneering studies of Middlebrock [I] a great deal of research has been directed at developing techniques for averaged modeling of different classes of switching converters [2] and for an automatic generation of the averaged models [3] The motivation of such studies was the selection of continuous models as simple as possible but adequate to capture all the main features of the switching converters in terms of stability dynamic characteristics and effectiveness for designing closed loop regulators A large number of possible nonlinear controllers have been proposed among others sliding mode control strategies [4] nonlinear PI controllers based on the method of extended linearization [5] and nonlinear H controllers [6] A recent interesting paper [7] presents the results of an experimental comparison of five control algorithms on a boost converter linear averaged controller feedback linearizing controller passivity-based controller sliding mode controller sliding mode plus passivity-based controller are compared along with their adaptive versions in order to cope with the parameter uncertainty due to a load resistance change Advantages and drawbacks of the proposed control strategies are tested under a fixed output voltage with load variations All the quoted literature comply with the more general problem of applying nonlinear control techniques to complex real world technical problems such classical approach has undoubtedly the advantage of designing analytical controllers and to evaluate quantitatively their stability bounds The major problem of the classical approach remains that as the complexity of system increases our ability to make precise and yet significant statements about its behavior diminishes [8] In our opinion the control of switching converter constitutes at the present time a borderline problem which can be handled both with conventional nonlinear control strategies and with fuzzy logic-based technologies Why can be fuzzy logic chosen as an alternative design method to nonlinear controllers An important answer was given in [9] a nonlinear controller such as
0-7803-8379-604$2000 02004 IEEE
mchouikha[amphowardedu
fuzzy logic can be inexpensively implemented with DSP-based micrc-controller As a matter of fact many researchers focused their efforts on the application of fuzzy technology for controlling switching converters In [9] the advantages of a low cost micro- controller implementation of a fuzzy direct control were pointed out A model- based fuzzy controller (fuzzy indirect control) for a Buck converter was proposed in [lo] Bonissone [ 1 11 proposed a successful application for resonant converters by using suitable scaling factors In [ 1 1 1 the fuzzy controller performs a variable action depending on the difference between the desired and the actual output voltage Such implementation considers an optimization of the scaling factors around a single output operating point
Our goal is to implement a robust fuzzy controller that can achieve the following properties 1) Robusmess around the operating point (eg in the case of a load change 2) Good dynamic performance (ie rise time overshoot settling time and limited output ripple) in the presence of input voltage variations (and load changes) and 3) Invariant dynamic performance in presence of varying operating conditions To the best of our knowledge property 1 has been hlfilled in all related literature Property 2 requires the synthesis of a complex controller (fuzzy or nonlinear) able to optimize the transient performance Property 3 (along with I and 2) implies the synthesis of a global controller with optimized parameters for varying operating conditions Such task seems to be extremely hard however we believe that a complex nonlinear controller could be accomplished using --based controller
In this paper two distinct topologies-based fuzzy logic controllers (FLCs) using different types of DC-DC converters and at different operating modes are developed and presented In topology I the fuzzy controller requires only sensing of one inductor current and the output voltage However for topology 11 the output voltage is the only variable to be monitored For this topology two categories of tests that cover the two basic performance areas load regulation and line regulation are carried out to evaluate the controllers performance
FUZZY LOGIC -BASED CONTROL TOPOLOGY I In this topology the proposed fuzzy controller uses three
input variables 1 ) Output voltage error e 2 ) Inductor current error ei and 3) Inductor current iL A block diagram of the fuzzy controller structure is shown in Fig 1 While the output voltage reference is usually available as an external signal the inductor current reference depends on the operating point For this reason it is computed by means of a low-pass filter in the assumption that the dc value of the current is automatically adjusted by the converter according to the power balance condition The controller output variable is the switch duty cycle controller which is obtained by adding the outputs of two fuzzy controllers One fuzzy (P) gives the proportional part 6 of the duty cycle as a function ofe = I - i eu = U -U and iL
The other fuzzy (I) gives as increment of 61 which is then
479
integrated to provide an integral term 61 of the duty cycle6 = 6 + 6
Funq-P
Fig lFuzzy Controller-based Topology I
A Fuzzy Rules for Topology I A lFar from the set point When the output voltage is far from the set point (e is PB or NB) the corrective action must be strong meaning F should be NB or PB while 61 should be zero The basic control rules are IF e is PB AND iL is NORM THEN 6 is PB AND 6 is ZE IF e is NB AND iL is NORM THEN 6 is NB AND SI is ZE This shows that far from the set point the control action is denoted by the output voltage error provided the existence of the current limit A2 Close to the Set Point The current error must be taken properly into account in order to ensure stability and speed of response The goal in this region is centered in achieving a satisfactory dynamic performance with small sensitivity to parameter variations The control rules are according to energy balance and inductor current is far from the limit
IF e AND ei are both Zero 6 AND nd SI must be zero too (steady state condition) IF the output voltage error e is Negative AND inductor current is greater than the reference value (ei lt 0) 6 and should be negative IF output voltage error is Positive AND the inductor current is greater its reference value THEN 6 and 6 I
must be kept to zero to prevent undershoot and overshoot IF the output voltage is Positive AND the current is lower than its reference value (ei gt 0) 6 and 6 must be positive the system energy increases in this condition
1
1
FUZZY LOGIC-BASED CONTROL TOPOLOGY I1 The block diagram of the fuzzy logic control scheme of
topology I1 for the DC-DC converter is shown in Fig2 The output is the duty cycle Fk For this topology there are two inputs the voltage error e = U -U and the change of the
voltage errorce = e - ek- The term U is the present output voltage and Uf is the reference output voltage
Fuzzy Rules for Topology I1 The derivation of the fuzzy control rules is heuristic and
based on the following criteria 1) IF the output of the converter is far from the set point the change of the duty cycle must be large to bring the output to the set point quickly 2) IF the output of the converter is approaching the set point a small change of duty cycle is necessary 3) IF the output of the converter is near the set point AND is approaching it rapidly the duty cycle must
be kept constant to prevent overshoot 4) IF the set point is reached AND the output still changing the duty cycle must be changed a little bit to prevent the output from moving away 5) IF the set point is reached AND the output is steady the duty cycle remains unchanged and 6) IF the output is above the set point the sign of the change of the duty cycle must be negative and vice versa
I I
Data Base
Fig 2 Block Diagram of Fuzzy Controller for Topology I1
SIMULATION RESULTS A Control Topology I
This control topology is tested using two different types of DC-DC converters namely the buck-boost converter and the sepic converter subject to step load change For the buck-boost converter the system information are as follows U = 12 V Uoref = 20 V Iref = 35 A Load changes from 20 R to 150 R and back
IL(t) Figs 3-5 show the output voltage the inductor current and the duty cycle as functions of the time
to 20a E (t) = Uoref-Uo(t) = 20 - u(t) El (t) = If -IL(t) = 35 -
Fig 3 Output voltage for the buck-boost converter
Time m i I I Fig 4 Inductor current for the buck-boost converter
480
Fig 5 Duty cycle of the buck-boost converter
For the sepic converter the system information is as follows U = 15 V Uorcf = 20 V Ircf = 36 A Load changes from 20 R to 200 R and back to 2022 Figs 6-8 display the output voltage the inductor current and the duty cycle as functions of the time
I 8 5 0 5 10 15 20 25
Time ms
Fig 6 Output voltage for the sepic converter
Time ms
Fig 7 Inductor current for the sepic converter
15 I
10 6 $ 5
0 -5
P)
gt 5 - 0 0
P p -10
_I
Time ms -I5 1- Fig 8 Duty cycle for the sepic converter
B Control Topology I1 This control topology is tested using three types of DC-
DC converters namely buck converter boost converter and buck-boost converter subject to input voltage change and load impedance change So we will have six cases namely
Case A Load regulation of buck-boost converter load resistance has step changes from 10 R to 5 C2 and back to 10 R Case B Line Regulation of Buck-Boost Converter Input has step changes from 15 V to 20 V and back to 15 V
Figs 9 and 10 show the output voltage and the duty cycle of the buck-boost converter subject to step load change from 10 R to 5 R and back to IOR It is shown that when the load voltage decreases from its set point at time 003 seconds due to increase in the load resistance the duty cycle increases severing to stabilize the output voltage As the output voltage increases from the set point at time 00325 seconds due to increase in the load resistance the duty cycle decreases trying to stabilize the voltage again at the set point Figs 11-13 show the input voltage change output voltage and the duty cycle of the buck-boost converter subject to step input voltage change from 15 V to 20 V and back to 15 V It is noticed in this case there is more ripples than the other cases
0 I 0015 0025 0035 0045 0055 0065
Time Sec
Fig 9 Output voltage for buck-boost converter subject to step change in the load resistance
Fig I O Duty cycle for buck-boost converter subject to step change in the load resistance
Fig 11 Input voltage variation for Buck-Boost Converter
48 1
rdquorsquo1 1 - 0 a 0015 0035 0055
Time sec
Fig 12 Output voltage for buck-boost converter subject to step change in the input voltage
I 3 1
Time ms
Fig 13 Duty cycle for buck-boost converter subject to step change in the input voltage
CONCLUSIONS Two hzzy control topologies are designed and
implemented the differences between the two structures are basically in the input variables and in the number of fuzzy logic rules Many test cases via simulation demonstrate that the two fuzzy topologies are capably in reducing the effect of different disturbances such as load changes and input voltage changes on different types of DCDC converters Simulation results show the ease of applying fuzzy control to dcdc converters as an interesting alternative to conventional techniques Also test results illustrate that the fuzzy logic approach can provide considerable control performances Fuzzy logic appears to be a valid element for generalization to many control applications The control topologies designed and simulated in this paper is a relatively easy to implement in the laboratory
REFERENCES R D Middlebrook and S Cuk Advances in Switched Mode Power Conversion vol 1 and 2 TESLAco Pasadena CA 198 1
SR Sanders JM Noworolsky XZ Liu and GC Verghese ldquoGeneralized averaging method for power conversion circuitsrdquo IEEE Trans Power Electronics vol 6 pp 251-259 Apr 1991
J Sun and H Grotstollen ldquoSymbolic analysis methods for averaged modeling of switching power convertersrdquo IEEE Trans Power Electronics vol 12 pp 537-546 May 1997
4
5
6
7
8
9
IO
1 I
H Sira-Ramirez ldquoSliding motions in bilinear switched networksrdquo IEEE Trans Circuits Systems vol CAS-34 pp 919-933 Aug 1987
H Sira-Ramirez ldquoDesign of P-I controllers for DC-to-DC power supplies via extended linearizationrdquo Int J Control vol 51 no 3 pp 601-620 1990
Kugi and K Schlacher ldquoNonlinear amp-controller design for a DC-to-DC power converterrdquo IEEE Trans Contr System Technology vol 7 pp 230-237 Mar 1999
G Escobar R Ortega H Sira-Ramirez JP Vilain and I Zein ldquoAn experimental comparison of several nonlinear controllers for power convertersrdquo IEEE Control Systems vol 19 no 1 pp 66-82 Febr 1999
LA Zadeh ldquoOutline of a new approach to the analysis of complex systems and decision processesrdquo IEEE Trans System Man amp Cybernetics vol SMC-3 pp 2 8 4 1973
T Gupta RR Boudreaux RM Nelms and J Hung ldquoImplementation of a fuzzy controller for DC-DC converters using an inexpensive 8-b microcontrollerrdquo IEEE Trans Industrial Electronics vol 44 no5 pp 661-669 Oct 1997
P Carbonell and JL Navarro ldquoLocal model-based fuzzy control of switch-mode DCDC convertersrdquo in Proc 14rdquo IFAC Triennal World Congress pp 237-242 1999
PP Bonissone PS Khedkar and M Schutten ldquoFuzzy logic control of resonant converters for power suppliesrdquo in Proc of the 4th IEEE Conference on Control Applications pp 323-328 1995
482
integrated to provide an integral term 61 of the duty cycle6 = 6 + 6
Funq-P
Fig lFuzzy Controller-based Topology I
A Fuzzy Rules for Topology I A lFar from the set point When the output voltage is far from the set point (e is PB or NB) the corrective action must be strong meaning F should be NB or PB while 61 should be zero The basic control rules are IF e is PB AND iL is NORM THEN 6 is PB AND 6 is ZE IF e is NB AND iL is NORM THEN 6 is NB AND SI is ZE This shows that far from the set point the control action is denoted by the output voltage error provided the existence of the current limit A2 Close to the Set Point The current error must be taken properly into account in order to ensure stability and speed of response The goal in this region is centered in achieving a satisfactory dynamic performance with small sensitivity to parameter variations The control rules are according to energy balance and inductor current is far from the limit
IF e AND ei are both Zero 6 AND nd SI must be zero too (steady state condition) IF the output voltage error e is Negative AND inductor current is greater than the reference value (ei lt 0) 6 and should be negative IF output voltage error is Positive AND the inductor current is greater its reference value THEN 6 and 6 I
must be kept to zero to prevent undershoot and overshoot IF the output voltage is Positive AND the current is lower than its reference value (ei gt 0) 6 and 6 must be positive the system energy increases in this condition
1
1
FUZZY LOGIC-BASED CONTROL TOPOLOGY I1 The block diagram of the fuzzy logic control scheme of
topology I1 for the DC-DC converter is shown in Fig2 The output is the duty cycle Fk For this topology there are two inputs the voltage error e = U -U and the change of the
voltage errorce = e - ek- The term U is the present output voltage and Uf is the reference output voltage
Fuzzy Rules for Topology I1 The derivation of the fuzzy control rules is heuristic and
based on the following criteria 1) IF the output of the converter is far from the set point the change of the duty cycle must be large to bring the output to the set point quickly 2) IF the output of the converter is approaching the set point a small change of duty cycle is necessary 3) IF the output of the converter is near the set point AND is approaching it rapidly the duty cycle must
be kept constant to prevent overshoot 4) IF the set point is reached AND the output still changing the duty cycle must be changed a little bit to prevent the output from moving away 5) IF the set point is reached AND the output is steady the duty cycle remains unchanged and 6) IF the output is above the set point the sign of the change of the duty cycle must be negative and vice versa
I I
Data Base
Fig 2 Block Diagram of Fuzzy Controller for Topology I1
SIMULATION RESULTS A Control Topology I
This control topology is tested using two different types of DC-DC converters namely the buck-boost converter and the sepic converter subject to step load change For the buck-boost converter the system information are as follows U = 12 V Uoref = 20 V Iref = 35 A Load changes from 20 R to 150 R and back
IL(t) Figs 3-5 show the output voltage the inductor current and the duty cycle as functions of the time
to 20a E (t) = Uoref-Uo(t) = 20 - u(t) El (t) = If -IL(t) = 35 -
Fig 3 Output voltage for the buck-boost converter
Time m i I I Fig 4 Inductor current for the buck-boost converter
480
Fig 5 Duty cycle of the buck-boost converter
For the sepic converter the system information is as follows U = 15 V Uorcf = 20 V Ircf = 36 A Load changes from 20 R to 200 R and back to 2022 Figs 6-8 display the output voltage the inductor current and the duty cycle as functions of the time
I 8 5 0 5 10 15 20 25
Time ms
Fig 6 Output voltage for the sepic converter
Time ms
Fig 7 Inductor current for the sepic converter
15 I
10 6 $ 5
0 -5
P)
gt 5 - 0 0
P p -10
_I
Time ms -I5 1- Fig 8 Duty cycle for the sepic converter
B Control Topology I1 This control topology is tested using three types of DC-
DC converters namely buck converter boost converter and buck-boost converter subject to input voltage change and load impedance change So we will have six cases namely
Case A Load regulation of buck-boost converter load resistance has step changes from 10 R to 5 C2 and back to 10 R Case B Line Regulation of Buck-Boost Converter Input has step changes from 15 V to 20 V and back to 15 V
Figs 9 and 10 show the output voltage and the duty cycle of the buck-boost converter subject to step load change from 10 R to 5 R and back to IOR It is shown that when the load voltage decreases from its set point at time 003 seconds due to increase in the load resistance the duty cycle increases severing to stabilize the output voltage As the output voltage increases from the set point at time 00325 seconds due to increase in the load resistance the duty cycle decreases trying to stabilize the voltage again at the set point Figs 11-13 show the input voltage change output voltage and the duty cycle of the buck-boost converter subject to step input voltage change from 15 V to 20 V and back to 15 V It is noticed in this case there is more ripples than the other cases
0 I 0015 0025 0035 0045 0055 0065
Time Sec
Fig 9 Output voltage for buck-boost converter subject to step change in the load resistance
Fig I O Duty cycle for buck-boost converter subject to step change in the load resistance
Fig 11 Input voltage variation for Buck-Boost Converter
48 1
rdquorsquo1 1 - 0 a 0015 0035 0055
Time sec
Fig 12 Output voltage for buck-boost converter subject to step change in the input voltage
I 3 1
Time ms
Fig 13 Duty cycle for buck-boost converter subject to step change in the input voltage
CONCLUSIONS Two hzzy control topologies are designed and
implemented the differences between the two structures are basically in the input variables and in the number of fuzzy logic rules Many test cases via simulation demonstrate that the two fuzzy topologies are capably in reducing the effect of different disturbances such as load changes and input voltage changes on different types of DCDC converters Simulation results show the ease of applying fuzzy control to dcdc converters as an interesting alternative to conventional techniques Also test results illustrate that the fuzzy logic approach can provide considerable control performances Fuzzy logic appears to be a valid element for generalization to many control applications The control topologies designed and simulated in this paper is a relatively easy to implement in the laboratory
REFERENCES R D Middlebrook and S Cuk Advances in Switched Mode Power Conversion vol 1 and 2 TESLAco Pasadena CA 198 1
SR Sanders JM Noworolsky XZ Liu and GC Verghese ldquoGeneralized averaging method for power conversion circuitsrdquo IEEE Trans Power Electronics vol 6 pp 251-259 Apr 1991
J Sun and H Grotstollen ldquoSymbolic analysis methods for averaged modeling of switching power convertersrdquo IEEE Trans Power Electronics vol 12 pp 537-546 May 1997
4
5
6
7
8
9
IO
1 I
H Sira-Ramirez ldquoSliding motions in bilinear switched networksrdquo IEEE Trans Circuits Systems vol CAS-34 pp 919-933 Aug 1987
H Sira-Ramirez ldquoDesign of P-I controllers for DC-to-DC power supplies via extended linearizationrdquo Int J Control vol 51 no 3 pp 601-620 1990
Kugi and K Schlacher ldquoNonlinear amp-controller design for a DC-to-DC power converterrdquo IEEE Trans Contr System Technology vol 7 pp 230-237 Mar 1999
G Escobar R Ortega H Sira-Ramirez JP Vilain and I Zein ldquoAn experimental comparison of several nonlinear controllers for power convertersrdquo IEEE Control Systems vol 19 no 1 pp 66-82 Febr 1999
LA Zadeh ldquoOutline of a new approach to the analysis of complex systems and decision processesrdquo IEEE Trans System Man amp Cybernetics vol SMC-3 pp 2 8 4 1973
T Gupta RR Boudreaux RM Nelms and J Hung ldquoImplementation of a fuzzy controller for DC-DC converters using an inexpensive 8-b microcontrollerrdquo IEEE Trans Industrial Electronics vol 44 no5 pp 661-669 Oct 1997
P Carbonell and JL Navarro ldquoLocal model-based fuzzy control of switch-mode DCDC convertersrdquo in Proc 14rdquo IFAC Triennal World Congress pp 237-242 1999
PP Bonissone PS Khedkar and M Schutten ldquoFuzzy logic control of resonant converters for power suppliesrdquo in Proc of the 4th IEEE Conference on Control Applications pp 323-328 1995
482
Fig 5 Duty cycle of the buck-boost converter
For the sepic converter the system information is as follows U = 15 V Uorcf = 20 V Ircf = 36 A Load changes from 20 R to 200 R and back to 2022 Figs 6-8 display the output voltage the inductor current and the duty cycle as functions of the time
I 8 5 0 5 10 15 20 25
Time ms
Fig 6 Output voltage for the sepic converter
Time ms
Fig 7 Inductor current for the sepic converter
15 I
10 6 $ 5
0 -5
P)
gt 5 - 0 0
P p -10
_I
Time ms -I5 1- Fig 8 Duty cycle for the sepic converter
B Control Topology I1 This control topology is tested using three types of DC-
DC converters namely buck converter boost converter and buck-boost converter subject to input voltage change and load impedance change So we will have six cases namely
Case A Load regulation of buck-boost converter load resistance has step changes from 10 R to 5 C2 and back to 10 R Case B Line Regulation of Buck-Boost Converter Input has step changes from 15 V to 20 V and back to 15 V
Figs 9 and 10 show the output voltage and the duty cycle of the buck-boost converter subject to step load change from 10 R to 5 R and back to IOR It is shown that when the load voltage decreases from its set point at time 003 seconds due to increase in the load resistance the duty cycle increases severing to stabilize the output voltage As the output voltage increases from the set point at time 00325 seconds due to increase in the load resistance the duty cycle decreases trying to stabilize the voltage again at the set point Figs 11-13 show the input voltage change output voltage and the duty cycle of the buck-boost converter subject to step input voltage change from 15 V to 20 V and back to 15 V It is noticed in this case there is more ripples than the other cases
0 I 0015 0025 0035 0045 0055 0065
Time Sec
Fig 9 Output voltage for buck-boost converter subject to step change in the load resistance
Fig I O Duty cycle for buck-boost converter subject to step change in the load resistance
Fig 11 Input voltage variation for Buck-Boost Converter
48 1
rdquorsquo1 1 - 0 a 0015 0035 0055
Time sec
Fig 12 Output voltage for buck-boost converter subject to step change in the input voltage
I 3 1
Time ms
Fig 13 Duty cycle for buck-boost converter subject to step change in the input voltage
CONCLUSIONS Two hzzy control topologies are designed and
implemented the differences between the two structures are basically in the input variables and in the number of fuzzy logic rules Many test cases via simulation demonstrate that the two fuzzy topologies are capably in reducing the effect of different disturbances such as load changes and input voltage changes on different types of DCDC converters Simulation results show the ease of applying fuzzy control to dcdc converters as an interesting alternative to conventional techniques Also test results illustrate that the fuzzy logic approach can provide considerable control performances Fuzzy logic appears to be a valid element for generalization to many control applications The control topologies designed and simulated in this paper is a relatively easy to implement in the laboratory
REFERENCES R D Middlebrook and S Cuk Advances in Switched Mode Power Conversion vol 1 and 2 TESLAco Pasadena CA 198 1
SR Sanders JM Noworolsky XZ Liu and GC Verghese ldquoGeneralized averaging method for power conversion circuitsrdquo IEEE Trans Power Electronics vol 6 pp 251-259 Apr 1991
J Sun and H Grotstollen ldquoSymbolic analysis methods for averaged modeling of switching power convertersrdquo IEEE Trans Power Electronics vol 12 pp 537-546 May 1997
4
5
6
7
8
9
IO
1 I
H Sira-Ramirez ldquoSliding motions in bilinear switched networksrdquo IEEE Trans Circuits Systems vol CAS-34 pp 919-933 Aug 1987
H Sira-Ramirez ldquoDesign of P-I controllers for DC-to-DC power supplies via extended linearizationrdquo Int J Control vol 51 no 3 pp 601-620 1990
Kugi and K Schlacher ldquoNonlinear amp-controller design for a DC-to-DC power converterrdquo IEEE Trans Contr System Technology vol 7 pp 230-237 Mar 1999
G Escobar R Ortega H Sira-Ramirez JP Vilain and I Zein ldquoAn experimental comparison of several nonlinear controllers for power convertersrdquo IEEE Control Systems vol 19 no 1 pp 66-82 Febr 1999
LA Zadeh ldquoOutline of a new approach to the analysis of complex systems and decision processesrdquo IEEE Trans System Man amp Cybernetics vol SMC-3 pp 2 8 4 1973
T Gupta RR Boudreaux RM Nelms and J Hung ldquoImplementation of a fuzzy controller for DC-DC converters using an inexpensive 8-b microcontrollerrdquo IEEE Trans Industrial Electronics vol 44 no5 pp 661-669 Oct 1997
P Carbonell and JL Navarro ldquoLocal model-based fuzzy control of switch-mode DCDC convertersrdquo in Proc 14rdquo IFAC Triennal World Congress pp 237-242 1999
PP Bonissone PS Khedkar and M Schutten ldquoFuzzy logic control of resonant converters for power suppliesrdquo in Proc of the 4th IEEE Conference on Control Applications pp 323-328 1995
482
rdquorsquo1 1 - 0 a 0015 0035 0055
Time sec
Fig 12 Output voltage for buck-boost converter subject to step change in the input voltage
I 3 1
Time ms
Fig 13 Duty cycle for buck-boost converter subject to step change in the input voltage
CONCLUSIONS Two hzzy control topologies are designed and
implemented the differences between the two structures are basically in the input variables and in the number of fuzzy logic rules Many test cases via simulation demonstrate that the two fuzzy topologies are capably in reducing the effect of different disturbances such as load changes and input voltage changes on different types of DCDC converters Simulation results show the ease of applying fuzzy control to dcdc converters as an interesting alternative to conventional techniques Also test results illustrate that the fuzzy logic approach can provide considerable control performances Fuzzy logic appears to be a valid element for generalization to many control applications The control topologies designed and simulated in this paper is a relatively easy to implement in the laboratory
REFERENCES R D Middlebrook and S Cuk Advances in Switched Mode Power Conversion vol 1 and 2 TESLAco Pasadena CA 198 1
SR Sanders JM Noworolsky XZ Liu and GC Verghese ldquoGeneralized averaging method for power conversion circuitsrdquo IEEE Trans Power Electronics vol 6 pp 251-259 Apr 1991
J Sun and H Grotstollen ldquoSymbolic analysis methods for averaged modeling of switching power convertersrdquo IEEE Trans Power Electronics vol 12 pp 537-546 May 1997
4
5
6
7
8
9
IO
1 I
H Sira-Ramirez ldquoSliding motions in bilinear switched networksrdquo IEEE Trans Circuits Systems vol CAS-34 pp 919-933 Aug 1987
H Sira-Ramirez ldquoDesign of P-I controllers for DC-to-DC power supplies via extended linearizationrdquo Int J Control vol 51 no 3 pp 601-620 1990
Kugi and K Schlacher ldquoNonlinear amp-controller design for a DC-to-DC power converterrdquo IEEE Trans Contr System Technology vol 7 pp 230-237 Mar 1999
G Escobar R Ortega H Sira-Ramirez JP Vilain and I Zein ldquoAn experimental comparison of several nonlinear controllers for power convertersrdquo IEEE Control Systems vol 19 no 1 pp 66-82 Febr 1999
LA Zadeh ldquoOutline of a new approach to the analysis of complex systems and decision processesrdquo IEEE Trans System Man amp Cybernetics vol SMC-3 pp 2 8 4 1973
T Gupta RR Boudreaux RM Nelms and J Hung ldquoImplementation of a fuzzy controller for DC-DC converters using an inexpensive 8-b microcontrollerrdquo IEEE Trans Industrial Electronics vol 44 no5 pp 661-669 Oct 1997
P Carbonell and JL Navarro ldquoLocal model-based fuzzy control of switch-mode DCDC convertersrdquo in Proc 14rdquo IFAC Triennal World Congress pp 237-242 1999
PP Bonissone PS Khedkar and M Schutten ldquoFuzzy logic control of resonant converters for power suppliesrdquo in Proc of the 4th IEEE Conference on Control Applications pp 323-328 1995
482