Combined feedforward and feedback parameter estimation for electric machines

• US 6,900,607 B2
• Filed: 12/11/2001
• Issued: 05/31/2005
• Est. Priority Date: 08/17/2001
• Status: Expired due to Term

• Current Assignee: GM Global Technology Operations Incorporated (General Motors Company), Steering Solutions IP Holding Corporation (Nexteer Automotive Group Ltd.)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Collier-Hallman, Steven J., Shafer, Daniel W., Chandy, Ashok, Kleinau, Julie A., Patankar, Ravindra P., Zuraski, Jeffery A.
• Primary Examiner(s): Hsieh, Shih-Yung
• Assistant Examiner(s): Martin, Edgardo San
• Application Number:
  US10/013,933
• Publication Number:
  US 20030076061A1
• Time in Patent Office: 1,267 Days
• Field of Search: 318/432, 318/783, 318/788, 318/791, 318/792, 318/798, 318/806, 318/433, 318/434, 318/471, 318/472, 318/473, 180/443, 180/446, 388/934, 322/33, 322/34, 337/298
• US Class Current: 318/432
• CPC Class Codes: B62D 5/0496 by using a temperature sensor
• CPC Class Codes: G01K 7/21 for modifying the output characteristic, e.g. linearising
• CPC Class Codes: G05B 13/04 involving the use of models or simulators
• CPC Class Codes: H02P 23/14 Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage
• CPC Class Codes: Y10S 388/934 Thermal condition

Abstract

A method and system for estimating a parameter of an electric machine, including a controller and a switching device, the controller responsive to at least one of: a current sensor, and a temperature sensor. Where the controller executes a parameter estimation process, which is responsive to at least one of: a current value, a torque command and the resultant of the parameter estimation process representing an estimated parameter of the electric machine. The parameter estimation includes a method for estimating a temperature of the electric machine comprising: a temperature sensor operatively connected to and transmitting a temperature signal corresponding to a measured temperature to a controller, which executes a temperature estimation process responsive to a temperature signal from a temperature sensor.

Claims

1. A system for estimating a parameter of an electric machine, comprising:

a controller operatively connected to a switching device said switching device operatively connected between said electric machine and a power source, said switching device being coupled to said controller;

a current sensor operatively connected to and transmitting a current value indicative of a current in said electric machine;

a temperature sensor operatively connected to and transmitting a temperature signal corresponding to a measured temperature to said controller; and

said controller executing a parameter estimation process responsive to at least one of;

a temperature value responsive to said temperature signal, said current value, and a torque command indicative of a desired torque for said electric machine, wherein a resultant of said parameter estimation process represents a parameter of said electric machine.

2. The system of claim 1 wherein said electric machine comprises an electric motor.

3. The system of claim 1 wherein said parameter comprises at least one of a resistance, an inductance, and a motor constant.

4. The system of claim 1 wherein said current value is representative of a torque current for said electric machine.

5. The system of claim 1 wherein said parameter estimation process comprises a feedback estimation methodology.

6. The system of claim 5 wherein said feedback estimation methodology comprises a closed loop compensation for build and life variations in said parameter of said electric machine.

7. The system of claim 5 further including a velocity sensor disposed to measure a velocity of said electric machine and transmitting a velocity signal to said controller and wherein said feedback estimation methodology is responsive to said torque command signal, said current value, and said velocity signal.

8. The system of claim 5 wherein said feedback estimation methodology includes comparing said torque command signal with an estimated torque in a time coherent manner to generate a torque error.

9. The system of claim 8 wherein said estimated torque is responsive to said current value, a velocity signal, and an earlier parameter estimate.

10. The system of claim 9 wherein said earlier parameter estimate is an earlier motor constant estimate.

11. The system of claim 8 wherein said feedback estimation methodology includes an error accumulator, which generates said parameter estimate in response to said torque error.

12. The system of claim 11 wherein said error accumulator comprises a conditional integrator.

13. The method of claim 11 wherein said error accumulator is initialized to a zero condition.

14. The system of claim 11 wherein said error accumulator is initialized to a nominal value of said parameter.

15. The system of claim 11 wherein said error accumulator is initialized to a saved value of said error accumulator, said saved value updated with a current output of said error accumulator only if said current output of said error accumulator exhibits a change in excess of a selected threshold.

16. The system of claim 5 wherein said controller receives an estimate good flag.

17. The system of claim 16 wherein said estimate good flag is indicative of a validity of said estimated torque.

18. The system of claim 16 wherein said feedback estimation methodology is responsive to said estimate good flag.

19. The system of claim 18 wherein said feedback estimation methodology is disabled when said estimate good flag indicates an invalid estimated torque.

20. The system of claim 5 wherein said controller receives a rate flag.

21. The system of claim 20 wherein said rate flag is indicative of current dynamics beyond a selected threshold.

22. The system of claim 21 wherein said feedback estimation methodology is disabled when said rate flag indicates current dynamics beyond said selected threshold.

23. The system of claim 22 wherein said selected threshold is two amperes over a 2 millisecond duration.

24. The system of claim 1 wherein said temperature sensor comprises a thermistor.

25. The system of claim 1 wherein said controller executes a process for linearizing said temperature signal.

26. The system of claim 25 wherein said linearizing comprises processing via a linearization function mechanism, with said output of said temperature sensor being provided to an input of said linearization function mechanism and an output of said linearization function mechanism being provided to an input of said parameter estimation process.

27. The system of claim 1 wherein said parameter estimation process includes a feedforward estimation methodology responsive to said temperature value.

28. The system of claim 27 wherein said feedforward estimation methodology comprises compensation for temperature variations of said parameter, said compensation employing a temperature coefficient of said parameter.

29. The system of claim 28 wherein said temperature value is responsive to a temperature estimation process.

30. The system of claim 29 wherein said temperature estimation process is implemented by at least one of:

a silicon temperature estimate filter, responsive to said output from said temperature sensor, said silicon temperature estimate filter having an output corresponding to an estimated temperature of a switching device for said electric machine;

a magnet temperature estimate filter, responsive to said output from said temperature sensor, said magnet temperature estimate filter having an output corresponding to an estimated temperature of a magnet associated with said electric machine; and

a copper winding temperature estimate filter responsive to said output from said temperature sensor, said copper winding temperature estimate filter having an output corresponding to an estimated temperature of copper windings associated with said electric machine.

31. The system of claim 30 wherein said silicon temperature estimate filter, said magnet temperature estimate filter, and said copper winding temperature estimate filter are first order, lead-lag filters.

32. The system of claim 31 wherein said silicon temperature estimate filter includes a lag frequency range between about 53 μ

Hz and about 320 μ

Hz and a lead frequency range between about 53 μ

Hz and about 160 μ

Hz.

33. The system of claim 31 wherein said magnet temperature estimate filter includes a lag frequency range between about 35 μ

Hz and about 80 μ

Hz and a lead frequency range between about 53 μ

Hz and about 160 μ

Hz.

34. The system of claim 31 wherein said copper winding temperature estimate filter includes a lag frequency range between about 35 μ

Hz and about 80 μ

Hz and a lead frequency range between about 53 μ

Hz and about 160 μ

Hz.

35. The system of claim 29 further comprising an initialization signal in communication with said controller.

36. The system of claim 35 wherein said initialization signal initializes said temperature estimation process to a substrate temperature corresponding to a linearized output of said temperature sensor.

37. The system of claim 35 wherein said initialization signal initializes said temperature estimation process by continuing to operate following power down until said temperature estimation process approaches an approximately steady state value.

38. The system of claim 35 wherein said initialization signal initializes said temperature estimation process to an initial value based on temperature estimates responsive to another temperature sensor.

39. The system of claim 38 wherein said another temperature sensor is an engine coolant sensor.

40. The system of claim 35 wherein said initialization signal is responsive to a computed duration of temperature change as a function of said another temperature sensor.

41. The system of claim 40 wherein said temperature estimation process computes a temperature T_x in accordance with the equation:

$T_x=T_a+\left(T_{\mathrm{x0}}-T_a\right)<br><br>{\left(\frac{T_e-T_a}{T_{\mathrm{e0}}-T_a}\right)}^{\frac{{\mathrm{\tau <br><br>}}_e}{{\mathrm{\tau <br><br>}}_x}}$

where;

T_x indicates a generalized a temperature for a material,

T_x0 indicates a generalized initial temperature for T_x,

T_e is the engine coolant temperature,

T_e0 is the hot engine coolant temperature when the ignition is first turned off,

T_a is the ambient temperature,

τ

_e is the cooling time constant for the engine,

τ

_x is the cooling time constant for the material.

42. The system of claim 35 wherein said initialization signal initializes said temperature estimation process to an ambient temperature.

43. The system of claim 35 wherein said initialization signal initializes said temperature estimation process to an ambient temperature estimate.

44. The system of claim 43 wherein said ambient temperature estimate comprises a filter having a cutoff frequency sized to estimate a thermal time constant of said electric machine.

45. The system of claim 44 wherein said ambient temperature estimate comprises a first order, lag filter.

46. The system of claim 45 wherein said first order, lag filter includes a lag frequency range between about 35 μ

Hz and about 80 μ

Hz.

47. The system of claim 35 wherein said temperature estimation process is implemented by at least one of:

a silicon temperature estimate filter, responsive to said output from said temperature sensor, said silicon temperature estimate filter having an output corresponding to an estimated temperature of a switching device for said electric machine;

a magnet temperature estimate filter, responsive to said output from said temperature sensor, said magnet temperature estimate filter having an output corresponding to an estimated temperature of a magnet associated with said electric machine; and

a copper winding temperature estimate filter responsive to said output from said temperature sensor, said copper winding temperature estimate filter having an output corresponding to an estimated temperature of copper windings associated with said electric machine.

48. The system of claim 47 wherein said silicon temperature estimate filter, said magnet temperature estimate filter, and said copper winding temperature estimate filter are first order, lead-lag filters.

49. The system of claim 48 wherein said silicon temperature estimate filter includes a lag frequency range between about 53 μ

Hz and about 320 μ

Hz and a lead frequency range between about 53 μ

Hz and about 160 μ

Hz.

50. The system of claim 48 wherein said magnet temperature estimate filter includes a lag frequency range between about 35 μ

Hz and about 80 μ

Hz and a lead frequency range between about 53 μ

Hz and about 160 μ

Hz.

51. The system of claim 48 wherein said copper winding temperature estimate filter includes a lag frequency range between about 35 μ

Hz and about 80 μ

Hz and a lead frequency range between about 53 μ

Hz and about 160 μ

Hz.

52. The system of claim 29 further comprising initializing said parameter estimate with an initialization signal said initialization signal in communication with said temperature estimation process.

53. The system of claim 1 wherein said parameter estimation process comprises a combination of a feedback estimation methodology and a feedforward estimation methodology.

54. The system of claim 53 wherein said combination is responsive to at least one of said torque command signal, said current value, said temperature value, and a velocity signal.

55. The system of claim 53 wherein said combination includes summing a parameter estimate correction from a feedback estimation methodology with a parameter estimate from a feedforward estimation methodology.

56. A method for estimating a parameter of an electric machine, comprising:

receiving a torque command signal indicative of a desired torque for said electric machine;

receiving a current value;

receiving a temperature value; and

wherein said estimating is a resultant of a parameter estimation process responsive to at least one of said torque command signal, said current value, and said temperature value, a resultant of said parameter estimation process representing said parameter of said electric machine.

57. The method of claim 56 wherein said electric machine comprises an electric motor.

58. The method of claim 56 wherein said parameter comprises at least one of a resistance, an inductance, and a motor constant.

59. The method of claim 56 wherein said current value is representative of a torque current for said electric machine.

60. The method of claim 56 wherein said parameter estimation process comprises a feedback estimation methodology.

61. The method of claim 60 wherein said feedback estimation methodology comprises a closed loop compensation for build and life variations in said parameter of said electric machine.

62. The method of claim 60 further including obtaining a velocity signal responsive to a velocity of said electric machine, wherein said feedback estimation methodology is responsive to said torque command signal, said current value, and said velocity signal.

63. The method of claim 60 wherein said feedback estimation methodology includes comparing said torque command signal with an estimated torque in a time coherent manner to generate a torque error.

64. The method of claim 63 wherein said estimated torque is responsive to said current value, a velocity signal, and an earlier parameter estimate.

65. The method of claim 64 wherein said earlier parameter estimate is an earlier motor constant estimate.

66. The method of claim 63 wherein said feedback estimation methodology includes an error accumulator, which generates said parameter estimate in response to said torque error.

67. The method of claim 66 wherein said error accumulator comprises a conditional integrator.

68. The method of claim 66 wherein said error accumulator is initialized to a zero condition.

69. The method of claim 66 wherein said error accumulator is initialized to a nominal value of said parameter.

70. The method of claim 66 wherein said error accumulator is initialized to a saved value of said error accumulator, said saved value updated with a current output of said error accumulator only if said current output of said error accumulator exhibits a change in excess of a selected threshold.

71. The method of claim 60 further comprising receiving an estimate good flag.

72. The method of claim 71 wherein said estimate good flag is indicative of a validity of said estimated torque.

73. The method of claim 71 wherein said feedback estimation methodology is responsive to said estimate good flag.

74. The method of claim 73 wherein said feedback estimation methodology is disabled when said estimate good flag indicates an invalid estimated torque.

75. The method of claim 60 further comprising receiving a rate flag.

76. The method of claim 75 wherein said rate flag is indicative of current dynamics beyond a selected threshold.

77. The method of claim 76 wherein said feedback estimation methodology is disabled when said rate flag indicates current dynamics beyond said selected threshold.

78. The method of claim 77 wherein said selected threshold is two amperes over a 2 millisecond duration.

79. The method of claim 56 wherein said temperature value is responsive to a temperature signal from a temperature sensor.

80. The method of claim 79 wherein said temperature sensor comprises a thermistor.

81. The method of claim 79 further comprising linearizing said temperature signal.

82. The method of claim 81 wherein said linearizing comprises processing via a linearization function mechanism interposed between said temperature sensor and said temperature estimation process, with said output of said temperature sensor being connected to an input of said linearization function mechanism and an output of said linearization function mechanism being connected to said input of said temperature estimation process.

83. The method of claim 56 wherein said parameter estimation process includes a feedforward estimation methodology responsive to said temperature value.

84. The method of claim 83 wherein said feedforward estimation methodology comprises compensation for temperature variations of said parameter, said compensation employing a temperature coefficient of said parameter.

85. The method of claim 84 wherein said temperature value is responsive to a temperature estimation process.

86. The method of claim 85 wherein said temperature estimation process further comprises at least one of:

a silicon temperature estimate filter, responsive to said output from said temperature sensor, said silicon temperature estimate filter having an output corresponding to an estimated temperature of a switching device for said electric machine;

a magnet temperature estimate filter, responsive to said output from said temperature sensor, said magnet temperature estimate filter having an output corresponding to an estimated temperature of a magnet associated with said electric machine; and

a copper winding temperature estimate filter responsive to said output from said temperature sensor, said copper winding temperature estimate filter having an output corresponding to an estimated temperature of copper windings associated with said electric machine.

87. The method of claim 86 wherein said silicon temperature estimate filter, said magnet temperature estimate filter, and said copper winding temperature estimate filter are first order, lead-lag filters.

88. The method of claim 87 wherein said silicon temperature estimate filter includes a lag frequency range between about 53 μ

Hz and about 320 μ

Hz and a lead frequency range between about 53 μ

Hz and about 160 μ

Hz.

89. The method of claim 87 wherein said magnet temperature estimate filter includes a lag frequency range between about 35 μ

Hz and about 80 μ

Hz and a lead frequency range between about 53 μ

Hz and about 160 μ

Hz.

90. The method of claim 87 wherein said copper winding temperature estimate filter includes a lag frequency range between about 35 μ

Hz and about 80 μ

Hz and a lead frequency range between about 53 μ

Hz and about 160 μ

Hz.

91. The method of claim 85 further comprising initializing said temperature estimation process with an initialization signal.

92. The method of claim 91 wherein said initialization signal initializes said temperature estimation process to a substrate temperature corresponding to a linearized output of said temperature sensor.

93. The method of claim 91 wherein said initialization signal initializes said temperature estimation process by continuing to operate following power down until said temperature estimation process approaches an approximately steady state value.

94. The method of claim 91 wherein said initialization signal initializes said temperature estimation process to an initial value based on temperature estimates responsive to another temperature sensor.

95. The method of claim 94 wherein said another temperature sensor is an engine coolant sensor.

96. The method of claim 94 wherein said initialization signal is responsive to a computed duration of temperature change as a function of said another temperature sensor.

97. The method of claim 96 wherein said temperature estimation process computes a temperature T_x in accordance with the equation:

$T_x=T_a+\left(T_{\mathrm{x0}}-T_a\right)<br><br>{\left(\frac{T_e-T_a}{T_{\mathrm{e0}}-T_a}\right)}^{\frac{{\mathrm{\tau <br><br>}}_e}{{\mathrm{\tau <br><br>}}_x}}$

where;

T_x indicates a generalized a temperature for a material,

T_x0 indicates a generalized initial temperature for T_x,

T_e is the engine coolant temperature,

T_e0 is the hot engine coolant temperature when the ignition is first turned off,

T_a is the ambient temperature,

τ

_e is the cooling time constant for the engine,

τ

_x is the cooling time constant for the material.

98. The method of claim 91 wherein said initialization signal initializes said temperature estimation process to an ambient temperature.

99. The method of claim 91 wherein said initialization signal initializes said temperature estimation process to an ambient temperature estimate.

100. The method of claim 99 wherein said ambient temperature estimate comprises a filter having a cutoff frequency sized to estimate a thermal time constant of said electric machine.

101. The method of claim 100 wherein said ambient temperature estimate comprises a first order, lag filter.

102. The method of claim 101 wherein said first order, lag filter includes a lag frequency range between about 35 μ

Hz and about 80 μ

Hz.

103. The method of claim 91 wherein said temperature estimation process comprises at least one of:

a silicon temperature estimate filter, responsive to said output from said temperature sensor, said silicon temperature estimate filter having an output corresponding to an estimated temperature of a switching device for said electric machine;

a magnet temperature estimate filter, responsive to said output from said temperature sensor, said magnet temperature estimate filter having an output corresponding to an estimated temperature of a magnet associated with said electric machine; and

a copper winding temperature estimate filter responsive to said output from said temperature sensor, said copper winding temperature estimate filter having an output corresponding to an estimated temperature of copper windings associated with said electric machine.

104. The method of claim 103 wherein said silicon temperature estimate filter, said magnet temperature estimate filter, and said copper winding temperature estimate filter are first order, lead-lag filters.

105. The method of claim 104 wherein said silicon temperature estimate filter includes a lag frequency range between about 53 μ

Hz and about 320 μ

Hz and a lead frequency range between about 53 μ

Hz and about 160 μ

Hz.

106. The method of claim 104 wherein said magnet temperature estimate filter includes a lag frequency range between about 35 μ

Hz and about 80 μ

Hz and a lead frequency range between about 53 μ

Hz and about 160 μ

Hz.

107. The method of claim 104 wherein said copper winding temperature estimate filter includes lag frequency range between about 35 μ

Hz and about 80 μ

Hz and a lead frequency range between about 53 μ

Hz and about 160 μ

Hz.

108. The method of claim 85 further comprising initializing said parameter estimate with an initialization signal said initialization signal in communication with said temperature estimation process.

109. The method of claim 56 wherein said parameter estimation process comprises a combination of a feedback estimation methodology and a feedforward estimation methodology.

110. The method of claim 109 wherein said combination is responsive to at least one of said torque command signal, said current value, said temperature value, and a velocity signal.

111. The method of claim 109 wherein said combination includes summing a parameter estimate correction from a feedback estimation methodology with a parameter estimate from a feedforward estimation methodology.

112. A storage medium encoded with computer program code;

said code including instructions for causing a controller to implement a method for estimating a parameter of an electric machine comprising;

receiving a torque command signal indicative of a desired torque for said electric machine;

receiving a current value;

receiving a temperature value; and

wherein said estimating is a resultant of a parameter estimation process responsive to at least one of said torque command signal, said current value, and said temperature value, a resultant of said parameter estimation process representing said parameter of said electric machine.

113. The storage medium of claim 112 wherein said parameter comprises at least one of a resistance, an inductance, and a motor constant.

114. The storage medium of claim 112 wherein said current value is representative of a torque current for said electric machine.

115. The storage medium of claim 112 wherein said parameter estimation process comprises a feedback estimation methodology.

116. The storage medium of claim 115 wherein said feedback estimation methodology comprises a closed loop compensation for build and life variations in said parameter of said electric machine.

117. The storage medium of claim 115 further including a velocity signal responsive to a velocity of said electric machine, wherein said feedback estimation methodology is responsive to said torque command signal, said current value, and said velocity signal.

118. The storage medium of claim 115 wherein said feedback estimation methodology includes comparing said torque command signal with an estimated torque in a time coherent manner to generate a torque error.

119. The storage medium of claim 118 wherein said estimated torque is responsive to said current value, a velocity signal, and an earlier parameter estimate.

120. The storage medium of claim 119 wherein said earlier parameter estimate is an earlier motor constant estimate.

121. The storage medium of claim 118 wherein said feedback estimation methodology includes an error accumulator, which generates said parameter estimate in response to said torque error.

122. The storage medium of claim 121 wherein said error accumulator comprises a conditional integrator.

123. The storage medium of claim 121 wherein said error accumulator is initialized to a zero condition.

124. The storage medium of claim 121 wherein said error accumulator is initialized to a nominal value of said parameter.

125. The storage medium of claim 121 wherein said error accumulator is initialized to a saved value of said error accumulator, said saved value updated with a current output of said error accumulator only if said current output of said error accumulator exhibits a change in excess of a selected threshold.

126. The storage medium of claim 115 further comprising instructions for causing said controller to implement a method further comprising receiving an estimate good flag.

127. The storage medium of claim 126 wherein said estimate good flag is indicative of a validity of said estimated torque.

128. The storage medium of claim 115 further comprising instructions for causing said controller to implement a method further comprising receiving a rate flag.

129. The storage medium of claim 128 wherein said rate flag is indicative of current dynamics beyond a selected threshold.

130. The storage medium of claim 129 wherein said feedback estimation methodology is disabled when said rate flag indicates current dynamics beyond said selected threshold.

131. The storage medium of claim 112 wherein said temperature value is responsive to a temperature signal from a temperature sensor.

132. The storage medium of claim 131 further comprising instructions for causing said controller to implement a method further comprising linearizing said temperature signal.

133. The storage medium of claim 112 wherein said parameter estimation process includes a feedforward estimation methodology responsive to said temperature value and wherein said temperature value is responsive to a temperature estimation process.

134. The storage medium of claim 133 wherein said feedforward estimation methodology comprises compensation for temperature variations of said parameter, said compensation employing a temperature coefficient of said parameter.

135. The storage medium of claim 134 wherein said temperature estimation process further comprises at least one of:

a silicon temperature estimate filter, responsive to said output from said temperature sensor, said silicon temperature estimate filter having an output corresponding to an estimated temperature of a switching device for said electric machine;

a magnet temperature estimate filter, responsive to said output from said temperature sensor, said magnet temperature estimate filter having an output corresponding to an estimated temperature of a magnet associated with said electric machine; and

a copper winding temperature estimate filter responsive to said output from said temperature sensor, said copper winding temperature estimate filter having an output corresponding to an estimated temperature of copper windings associated with said electric machine.

136. The storage medium of claim 133 further comprising instructions for causing said controller to implement a method further comprising initializing said temperature estimation process with an initialization signal.

137. The storage medium of claim 136 wherein said initialization signal initializes said temperature estimation process to a substrate temperature corresponding to a linearized output of said temperature sensor.

138. The storage medium of claim 136 wherein said initialization signal initializes said temperature estimation process by continuing to operate following power down until said temperature estimation process approaches an approximately steady state value.

139. The storage medium of claim 136 wherein said initialization signal is responsive to a computed duration of temperature change as a function of another temperature sensor.

140. The storage medium of claim 136 wherein said initialization signal initializes said temperature estimation process to an ambient temperature.

141. The storage medium of claim 136 wherein said initialization signal initializes said temperature estimation process to an ambient temperature estimate.

142. The storage medium of claim 136 wherein said temperature estimation process comprises at least one of:

a silicon temperature estimate filter, responsive to said output from said temperature sensor, said silicon temperature estimate filter having an output corresponding to an estimated temperature of a switching device for said electric machine;

a magnet temperature estimate filter, responsive to said output from said temperature sensor, said magnet temperature estimate filter having an output corresponding to an estimated temperature of a magnet associated with said electric machine; and

a copper winding temperature estimate filter responsive to said output from said temperature sensor, said copper winding temperature estimate filter having an output corresponding to an estimated temperature of copper windings associated with said electric machine.

143. The storage medium of claim 134 further comprising instructions for causing said controller to implement a method further comprising initializing said parameter estimate with an initialization signal said initialization signal in communication with said temperature estimation process.

144. The storage medium of claim 112 wherein said parameter estimation process comprises a combination of a feedback estimation methodology and a feedforward estimation methodology.

145. The storage medium of claim 144 wherein said combination is responsive to at least one of said torque command signal, said current value, said temperature value, and a velocity signal.

146. The storage medium of claim 144 wherein said combination includes summing a parameter estimate correction from a feedback estimation methodology with a parameter estimate from a feedforward estimation methodology.

147. A computer data signal embodied in a carrier wave, the computer data signal comprising:

code configured to cause a controller to implement a method for estimating a parameter of an electric machine comprising;

receiving a torque command signal indicative of a desired torque for said electric machine;

receiving a current value;

receiving a temperature value; and

wherein said estimating is a resultant of a parameter estimation process responsive to at least one of said torque command signal, said current value, and said temperature value, a resultant of said parameter estimation process representing said parameter of said electric machine.

148. The computer data signal of claim 147 wherein said parameter comprises at least one of a resistance, an inductance, and a motor constant.

149. The computer data signal of claim 147 wherein said current value is representative of a torque current for said electric machine.

150. The computer data signal of claim 147 wherein said parameter estimation process comprises a feedback estimation methodology.

151. The computer data signal of claim 150 wherein said feedback estimation methodology comprises a closed loop compensation for build and life variations in said parameter of said electric machine.

152. The computer data signal of claim 150 further including a velocity signal responsive to a velocity of said electric machine, wherein said feedback estimation methodology is responsive to said torque command signal, said current value, and said velocity signal.

153. The computer data signal of claim 150 wherein said feedback estimation methodology includes comparing said torque command signal with an estimated torque in a time coherent manner to generate a torque error.

154. The computer data signal of claim 153 wherein said estimated torque is responsive to said current value, a velocity signal, and an earlier parameter estimate.

155. The computer data signal of claim 154 wherein said earlier parameter estimate is an earlier motor constant estimate.

156. The computer data signal of claim 153 wherein said feedback estimation methodology includes an error accumulator, which generates said parameter estimate in response to said torque error.

157. The computer data signal of claim 156 wherein said error accumulator comprises a conditional integrator.

158. The computer data signal of claim 156 wherein said error accumulator is initialized to a zero condition.

159. The computer data signal of claim 156 wherein said error accumulator is initialized to a nominal value of said parameter.

160. The computer data signal of claim 156 wherein said error accumulator is initialized to a saved value of said error accumulator, said saved value updated with a current output of said error accumulator only if said current output of said error accumulator exhibits a change in excess of a selected threshold.

161. The computer data signal of claim 150 further comprising instructions for causing said controller to implement a method further comprising receiving an estimate good flag.

162. The computer data signal of claim 160 wherein said estimate good flag is indicative of a validity of said estimated torque.

163. The computer data signal of claim 150 further comprising instructions for causing said controller to implement a method further comprising receiving a rate flag.

164. The computer data signal of claim 163 wherein said rate flag is indicative of current dynamics beyond a selected threshold.

165. The computer data signal of claim 164 wherein said feedback estimation methodology is disabled when said rate flag indicates current dynamics beyond said selected threshold.

166. The computer data signal of claim 147 wherein said temperature value is responsive to a temperature signal from a temperature sensor.

167. The computer data signal of claim 166 further comprising instructions for causing said controller to implement a method further comprising linearizing said temperature signal.

168. The computer data signal of claim 147 wherein said parameter estimation process includes a feedforward estimation methodology responsive to said temperature value and wherein said temperature value is responsive to a temperature estimation process.

169. The computer data signal of claim 168 wherein said feedforward estimation methodology comprises compensation for temperature variations of said parameter, said compensation employing a temperature coefficient of said parameter.

170. The computer data signal of claim 169 wherein said temperature estimation process further comprises at least one of:

a silicon temperature estimate filter, responsive to said output from said temperature sensor, said silicon temperature estimate filter having an output corresponding to an estimated temperature of a switching device for said electric machine;

a magnet temperature estimate filter, responsive to said output from said temperature sensor, said magnet temperature estimate filter having an output corresponding to an estimated temperature of a magnet associated with said electric machine; and

a copper winding temperature estimate filter responsive to said output from said temperature sensor, said copper winding temperature estimate filter having an output corresponding to an estimated temperature of copper windings associated with said electric machine.

171. The computer data signal of claim 168 further comprising instructions for causing said controller to implement a method further comprising initializing said temperature estimation process with an initialization signal.

172. The computer data signal of claim 171 wherein said initialization signal initializes said temperature estimation process to a substrate temperature corresponding to a linearized output of said temperature sensor.

173. The computer data signal of claim 171 wherein said initialization signal initializes said temperature estimation process by continuing to operate following power down until said temperature estimation process approaches an approximately steady state value.

174. The computer data signal of claim 171 wherein said initialization signal is responsive to a computed duration of temperature change as a function of another temperature sensor.

175. The computer data signal of claim 171 wherein said initialization signal initializes said temperature estimation process to an ambient temperature.

176. The computer data signal of claim 171 wherein said initialization signal initializes said temperature estimation process to an ambient temperature estimate.

177. The computer data signal of claim 171 wherein said temperature estimation process comprises at least one of:

a silicon temperature estimate filter, responsive to said output from said temperature sensor, said silicon temperature estimate filter having an output corresponding to an estimated temperature of a switching device for said electric machine;

a magnet temperature estimate filter, responsive to said output from said temperature sensor, said magnet temperature estimate filter having an output corresponding to an estimated temperature of a magnet associated with said electric machine; and

a copper winding temperature estimate filter responsive to said output from said temperature sensor, said copper winding temperature estimate filter having an output corresponding to an estimated temperature of copper windings associated with said electric machine.

178. The computer data signal of claim 169 further comprising instructions for causing said controller to implement a method further comprising initializing said parameter estimate with an initialization signal said initialization signal in communication with said temperature estimation process.

179. The computer data signal of claim 147 wherein said parameter estimation process comprises a combination of a feedback estimation methodology and a feedforward estimation methodology.

180. The computer data signal of claim 179 wherein said combination is responsive to at least one of said torque command signal, said current value, a velocity signal, and said temperature value.

181. The computer data signal of claim 179 wherein said combination includes summing a parameter estimate correction from a feedback estimation methodology with a parameter estimate from a feedforward estimation methodology.