Fuzzy control process for switching power supplies, and device for performing it

• US 5,696,439 A
• Filed: 06/30/1995
• Issued: 12/09/1997
• Est. Priority Date: 07/01/1994
• Status: Expired due to Term

• Current Assignee: Consorzio Per Il Sistema Informativo Csi Piemonte
• Original Assignee: Consorzio Per Il Sistema Informativo Csi Piemonte
• Inventors: D'Angelo, Giuseppe, Cucuccio, Antonino, Presti, Matteo Lo
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): Riley, Shawn
• Application Number:
  US08/497,726
• Time in Patent Office: 893 Days
• Field of Search: 323/222, 323/283, 323/290, 323/241, 323/286, 323/287, 363/75
• US Class Current: 323/283
• CPC Class Codes: G05B 13/0275 using fuzzy logic only
• CPC Class Codes: G06N 5/048 Fuzzy inferencing
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

A process for the fuzzy control of switching power supplies which have at least one inductor and at least one switching device, and a device for performing this control, the particularity whereof resides in the fact that it comprises the following steps: measuring the value of the current on the inductor; measuring the value of the input voltage of the switching power supply; measuring an error generated between a reference voltage and an output voltage of the power supply; defining fuzzy membership functions for the value of the current on the inductor, for the input voltage value, and for the error; defining an output membership function for the value of the duty cycle of the power supply; defining multiple fuzzy inference rules to which the measured values and the membership functions are applied calculating the corresponding weight functions of the membership functions; defuzzifying the results obtained by means of the weight function calculation and the application of fuzzy rules so as to obtain a real value of the duty cycle which is suitable to drive the switching device.

Claims

1. A process for the fuzzy control of a switching power supply which has at least one inductor and at least one switching device, comprising the following steps:

measuring a value of a current in said inductor;

measuring a value of an input voltage of said switching power supply;

measuring an error generated between a reference voltage and an output voltage of said power supply;

defining fuzzy membership functions for said value of the current in said inductor, for said input voltage value and for said error;

defining an output membership function for a value of a duty cycle of said power supply;

defining multiple fuzzy inference rules to which said measured values and said membership functions are applied;

calculating corresponding weight functions of said membership functions; and

defuzzifying results obtained by means of said weight function calculation and said application of fuzzy rules to obtain a real value of said duty cycle, which real value is for driving said switching device.

2. A process according to claim 1, wherein said process employs as said switching device a power transistor.

3. A process according to claim 2, further comprising the following steps:

measuring a value of a temperature of said power transistor; and

defining a membership function for said temperature value.

4. A process according to claim 3, further comprising the step of defining a membership function for the value of at least one of a base current and a gate voltage of said power transistor;

and wherein said defuzzification step generates a real value of said at least one of said base current and said gate voltage.

5. A process according to claim 4, wherein said process employs as said rules rules of an IF-THEN type, which rules define an antecedent and a consequent.

6. A process according to claim 5, wherein said defuzzification step comprises the calculation of centroids of the membership functions of said consequents.

7. A process according to claim 6, wherein said calculation of said weight functions occurs on said antecedents.

8. A process according to claim 5, wherein said calculation of said weight functions occurs on said antecedents.

9. A process according to claim 4, wherein said defuzzification step comprises the calculation of centroids of the membership functions of consequents.

10. A process according to claim 9, wherein said calculation of said weight functions occurs on antecedents.

11. A process according to claim 4, wherein said calculation of said weight functions occurs on antecedents.

12. A process according to claim 3, wherein said process employs as said rules rules of an IF-THEN type, which rules define an antecedent and a consequent.

13. A process according to claim 12, wherein said defuzzification step comprises the calculation of centroids of the membership functions of said consequents.

14. A process according to claim 13, wherein said calculation of said weight functions occurs on said antecedents.

15. A process according to claim 12, wherein said calculation of said weight functions occurs on said antecedents.

16. A process according to claim 3, wherein said defuzzification step comprises the calculation of centroids of the membership functions of consequents.

17. A process according to claim 16, wherein said calculation of said weight functions occurs on antecedents.

18. A process according to claim 3, wherein said calculation of said weight functions occurs on antecedents.

19. A process according to claim 2, further comprising the step of defining a membership function for the value of at least one of a base current and a gate voltage of said power transistor;

and wherein said defuzzification step generates a real value of said at least one of said base current and said gate voltage.

20. A process according to claim 19, wherein said process employs as said rules rules of an IF-THEN type, which rules define an antecedent and a consequent.

21. A process according to claim 20, wherein said defuzzification step comprises the calculation of centroids of the membership functions of said consequents.

22. A process according to claim 21, wherein said calculation of said weight functions occurs on said antecedents.

23. A process according to claim 20, wherein said calculation of said weight functions occurs on said antecedents.

24. A process according to claim 19, wherein said defuzzification step comprises the calculation of centroids of the membership functions of consequents.

25. A process according to claim 24, wherein said calculation of said weight functions occurs on antecedents.

26. A process according to claim 19, wherein said calculation of said weight functions occurs on antecedents.

27. A process according to claim 2, wherein said process employs as said rules rules of an IF-THEN type, which rules define an antecedent and a consequent.

28. A process according to claim 27, wherein said defuzzification step comprises the calculation of centroids of the membership functions of said consequents.

29. A process according to claim 28, wherein said calculation of said weight functions occurs on said antecedents.

30. A process according to claim 27, wherein said calculation of said weight functions occurs on said antecedents.

31. A process according to claim 2, wherein said defuzzification step comprises the calculation of centroids of the membership functions of consequents.

32. A process according to claim 31, wherein said calculation of said weight functions occurs on antecedents.

33. A process according to claim 2, wherein said calculation of said weight functions occurs on antecedents.

34. A process according to claim 1, further comprising the following steps:

measuring a value of a temperature of said power transistor; and

defining a membership function for said temperature value.

35. A process according to claim 34, further comprising the step of defining a membership function for the value of at least one of a base current and a gate voltage of said power transistor;

and wherein said defuzzification step generates a real value of said at least one of said base current and said gate voltage.

36. A process according to claim 35, wherein said process employs as said rules rules of an IF-THEN type, which rules define an antecedent and a consequent.

37. A process according to claim 36, wherein said defuzzification step comprises the calculation of centroids of the membership functions of said consequents.

38. A process according to claim 37, wherein said calculation of said weight functions occurs on said antecedents.

39. A process according to claim 36, wherein said calculation of said weight functions occurs on said antecedents.

40. A process according to claim 35, wherein said defuzzification step comprises the calculation of centroids of the membership functions of consequents.

41. A process according to claim 40, wherein said calculation of said weight functions occurs on antecedents.

42. A process according to claim 35, wherein said calculation of said weight functions occurs on antecedents.

43. A process according to claim 34, wherein said process employs as said rules rules of an IF-THEN type, which rules define an antecedent and a consequent.

44. A process according to claim 43, wherein said defuzzification step comprises the calculation of centroids of the membership functions of said consequents.

45. A process according to claim 44, wherein said calculation of said weight functions occurs on said antecedents.

46. A process according to claim 43, wherein said calculation of said weight functions occurs on said antecedents.

47. A process according to claim 34, wherein said defuzzification step comprises the calculation of centroids of the membership functions of consequents.

48. A process according to claim 47, wherein said calculation of said weight functions occurs on antecedents.

49. A process according to claim 34, wherein said calculation of said weight functions occurs on antecedents.

50. A process according to claim 1, further comprising the step of defining a membership function for the value of at least one of a base current and a gate voltage of said switching device;

and wherein said defuzzification step generates a real value of said at least one of said base current and said gate voltage.

51. A process according to claim 50, wherein said process employs as said rules rules of an IF-THEN type, which rules define an antecedent and a consequent.

52. A process according to claim 51, wherein said defuzzification step comprises the calculation of centroids of the membership functions of said consequents.

53. A process according to claim 52, wherein said calculation of said weight functions occurs on said antecedents.

54. A process according to claim 51, wherein said calculation of said weight functions occurs on said antecedents.

55. A process according to claim 50, wherein said defuzzification step comprises the calculation of centroids of the membership functions of consequents.

56. A process according to claim 55, wherein said calculation of said weight functions occurs on antecedents.

57. A process according to claim 50, wherein said calculation of said weight functions occurs on antecedents.

58. A process according to claim 1, wherein said process employs as said rules rules of an IF-THEN type, which rules define an antecedent and a consequent.

59. A process according to claim 58, wherein said defuzzification step comprises the calculation of centroids of the membership functions of said consequents.

60. A process according to claim 59, wherein said calculation of said weight functions occurs on said antecedents.

61. A process according to claim 58, wherein said calculation of said weight functions occurs on said antecedents.

62. A process according to claim 1, wherein said defuzzification step comprises the calculation of centroids of the membership functions of consequents.

63. A process according to claim 62, wherein said calculation of said weight functions occurs on antecedents.

64. A process according to claim 1, wherein said calculation of said weight functions occurs on antecedents.

129. A process according to claim 1 wherein the process controls a DC/DC converter as said power supply.

130. A process according to claim 129 wherein the process controls a flyback DC/DC converter as said power supply.

131. A process according to claim 4 wherein the process controls a DC/DC converter as said power supply.

132. A process according to claim 131 wherein the process controls a flyback DC/DC converter as said power supply.

65. A fuzzy control device for switching a power supply which has at least one inductor and at least one switching device comprising:

means for measuring a value of a current in said inductor;

means for measuring a value of an input voltage of said switching power supply;

means for detecting an error generated between a reference voltage and an output voltage of said power supply;

fuzzy inference means for applying said measured values and fuzzy membership functions for said current value on said inductor, for said input voltage value, for said error, and for a value of a duty cycle of said power supply, and

to a plurality of fuzzy inference rules,

means for calculating corresponding weight functions of said membership functions; and

means for defuzzifying results obtained by said means for calculating and said means for applying, said means for defuzzifying being for producing a real value of said duty cycle for driving said switching device, and said means for defuzzifying being responsive to said means for calculating.

66. A device according to claim 65, wherein said switching device is a power transistor.

67. A device according to claim 66, further comprising means for measuring a value of a temperature of said power transistor;

and wherein membership functions include a membership function for said temperature value.

68. A device according to claim 67, wherein:

said membership functions include a membership function for the value of at least one of a base current and a gate voltage of said power transistor; and

said defuzzification means are for generating a real value of said at least one of said base current and said gate voltage.

69. A device according to claim 68, wherein said fuzzy inference means are for applying said measured values and said membership functions to ones of said rules that are of an IF-THEN type and that define an antecedent and a consequent.

70. A device according to claim 69, wherein said defuzzification means are for calculating centroids of the membership functions of said consequents.

71. A device according to claim 70, wherein means for calculating performs said calculation of said weight functions on said antecedents.

72. A device according to claim 69, wherein means for calculating performs said calculation of said weight functions on said antecedents.

73. A device according to claim 68, wherein said defuzzification means are for calculating centroids of the membership functions of consequents.

74. A device according to claim 73, wherein means for calculating performs said calculation of said weight functions on antecedents.

75. A device according to claim 68, wherein means for calculating performs said calculation of said weight functions on antecedents.

76. A device according to claim 67, wherein said fuzzy inference means are for applying said measured values and said membership functions to ones of said rules that are of an IF-THEN type and that define an antecedent and a consequent.

77. A device according to claim 76, wherein said defuzzification means are for calculating centroids of the membership functions of said consequents.

78. A device according to claim 77, wherein means for calculating performs said calculation of said weight functions on said antecedents.

79. A device according to claim 76, wherein means for calculating performs said calculation of said weight functions on said antecedents.

80. A device according to claim 67, wherein said defuzzification means are for calculating centroids of the membership functions of consequents.

81. A device according to claim 80, wherein means for calculating performs said calculation of said weight functions on antecedents.

82. A device according to claim 67, wherein means for calculating performs said calculation of said weight functions on antecedents.

83. A device according to claim 66, wherein:

said membership functions include a membership function for the value of at least one of a base current and a gate voltage of said power transistor; and

said defuzzification means are for generating a real value of said at least one of said base current and said gate voltage.

84. A device according to claim 83, wherein said fuzzy inference means are for applying said measured values and said membership functions to ones of said rules that are of an IF-THEN type and that define an antecedent and a consequent.

85. A device according to claim 84, wherein said defuzzification means are for calculating centroids of the membership functions of said consequents.

86. A device according to claim 85, wherein means for calculating performs said calculation of said weight functions on said antecedents.

87. A device according to claim 84, wherein means for calculating performs said calculation of said weight functions on said antecedents.

88. A device according to claim 83, wherein said defuzzification means are for calculating centroids of the membership functions of consequents.

89. A device according to claim 88, wherein means for calculating performs said calculation of said weight functions on antecedents.

90. A device according to claim 83, wherein means for calculating performs said calculation of said weight functions on antecedents.

91. A device according to claim 66, wherein said fuzzy inference means are for applying said measured values and said membership functions to ones of said rules that are of an IF-THEN type and that define an antecedent and a consequent.

92. A device according to claim 91, wherein said defuzzification means are for calculating centroids of the membership functions of said consequents.

93. A device according to claim 92, wherein means for calculating performs said calculation of said weight functions on said antecedents.

94. A device according to claim 91, wherein means for calculating performs said calculation of said weight functions on said antecedents.

95. A device according to claim 66, wherein said defuzzification means are for calculating centroids of the membership functions of consequents.

96. A device according to claim 95, wherein means for calculating performs said calculation of said weight functions on antecedents.

97. A device according to claim 66, wherein means for calculating performs said calculation of said weight functions on antecedents.

98. A device according to claim 65, further comprising means for measuring a value of a temperature of said power transistor;

and wherein membership functions include a membership function for said temperature value.

99. A device according to claim 89, wherein:

said membership functions include a membership function for the value of at least one of a base current and a gate voltage of said power transistor; and

said defuzzification means are for generating a real value of said at least one of said base current and said gate voltage.

100. A device according to claim 99, wherein said fuzzy inference means are for applying said measured values and said membership functions to ones of said rules that are of an IF-THEN type and that define an antecedent and a consequent.

101. A device according to claim 100, wherein said defuzzification means are for calculating centroids of the membership functions of said consequents.

102. A device according to claim 101, wherein means for calculating performs said calculation of said weight functions on said antecedents.

103. A device according to claim 100, wherein means for calculating performs said calculation of said weight functions on said antecedents.

104. A device according to claim 99, wherein said defuzzification means are for calculating centroids of the membership functions of consequents.

105. A device according to claim 104, wherein means for calculating performs said calculation of said weight functions on antecedents.

106. A device according to claim 99, wherein means for calculating performs said calculation of said weight functions on antecedents.

107. A device according to claim 98, wherein said fuzzy inference means are for applying said measured values and said membership functions to ones of said rules that are of an IF-THEN type and that define an antecedent and a consequent.

108. A device according to claim 107, wherein said defuzzification means are for calculating centroids of the membership functions of said consequents.

109. A device according to claim 108, wherein means for calculating performs said calculation of said weight functions on said antecedents.

110. A device according to claim 107, wherein means for calculating performs said calculation of said weight functions on said antecedents.

111. A device according to claim 98, wherein said defuzzification means are for calculating centroids of the membership functions of consequents.

112. A device according to claim 111, wherein means for calculating performs said calculation of said weight functions on antecedents.

113. A device according to claim 98, wherein means for calculating performs said calculation of said weight functions on antecedents.

114. A device according to claim 65, wherein:

said membership functions include a membership function for the value of at least one of a base current and a gate voltage of said switching device; and

said defuzzification means are for generating a real value of said at least one of said base current and said gate voltage.

115. A device according to claim 114, wherein said fuzzy inference means are for applying said measured values and said membership functions to ones of said rules that are of an IF-THEN type and that define an antecedent and a consequent.

116. A device according to claim 115, wherein said defuzzification means are for calculating centroids of the membership functions of said consequents.

117. A device according to claim 116, wherein means for calculating performs said calculation of said weight functions on said antecedents.

118. A device according to claim 115, wherein means for calculating performs said calculation of said weight functions on said antecedents.

119. A device according to claim 114, wherein said defuzzification means are for calculating centroids of the membership functions of consequents.

120. A device according to claim 119, wherein means for calculating performs said calculation of said weight functions on antecedents.

121. A device according to claim 114, wherein means for calculating performs said calculation of said weight functions on antecedents.

122. A device according to claim 65, wherein said fuzzy inference means are for applying said measured values and said membership functions to ones of said rules that are of an IF-THEN type and that define an antecedent and a consequent.

123. A device according to claim 122, wherein said defuzzification means are for calculating centroids of the membership functions of said consequents.

124. A device according to claim 123, wherein means for calculating performs said calculation of said weight functions on said antecedents.

125. A device according to claim 122, wherein means for calculating performs said calculation of said weight functions on said antecedents.

126. A device according to claim 65, wherein said defuzzification means are for calculating centroids of the membership functions of consequents.

127. A device according to claim 126, wherein means for calculating performs said calculation of said weight functions on antecedents.

128. A device according to claim 65, wherein means for calculating performs said calculation of said weight functions on antecedents.

133. A fuzzy control device according to claim 65 wherein said power supply is a DC/DC converter.

134. A fuzzy control device according to claim 133 wherein the DC/DC converter is a flyback converter.

135. A fuzzy control device according to claim 68 wherein said power supply is a DC/DC converter.

136. A fuzzy control device according to claim 135 wherein the DC/DC converter is a flyback converter.