Overheat preventing apparatus for electric motor

• US 20060076840A1
• Filed: 10/07/2005
• Published: 04/13/2006
• Est. Priority Date: 10/13/2004
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Inventors: Tamagawa, Yutaka, Yamaguchi, Noritaka
• Granted Patent: US 7,583,041 B2
• Time in Patent Office: Days
• US Class Current: 310/53
• CPC Class Codes: B60L 1/003 to auxiliary motors, e.g. for pumps, compressors
• CPC Class Codes: B60L 1/02 to electric heating circuits
• CPC Class Codes: B60L 2240/36 Temperature of vehicle components or parts
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/425 Temperature
• CPC Class Codes: B60L 3/12 Recording operating variables ; Monitoring of operating variables
• CPC Class Codes: B60L 7/14 for vehicles propelled by ac motors
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility

Abstract

The present invention includes temperature transition estimating means 24, 25 for estimating a temperature transition of an electric motor 1 caused by the passage of electric current through the electric motor 1, an electric pump 8 as coolant supplying means for supplying a coolant to the electric motor, and coolant supply control means 26 to 28 for controlling the pump 8 according to the temperature transition of the electric motor 1 and the coolant temperature. The amount of operation of the electric pump 8 is determined from the temperature transition and the coolant temperature. This structure makes it possible to prevent overheating o the electric motor properly using the coolant while minimizing the energy consumption involved in using the coolant.

Claims

1. An overheat preventing apparatus for preventing an electric motor from overheating, comprising:

temperature transition estimating means for estimating a temperature transition of the electric motor caused by the passage of electric current through the electric motor;

coolant supplying means for supplying a coolant to the electric motor; and

coolant supply control means for controlling the amount of coolant supply from said coolant supplying means according to at least the estimated temperature transition of the electric motor.

2. The apparatus according to claim 1 further comprising coolant temperature sensing means for sensing the temperature of the coolant to be supplied to the electric motor,

wherein said coolant supply control means controls the amount of coolant supply from said coolant supplying means according to the sensed coolant temperature and the estimated temperature transition of the electric motor.

3. The apparatus according to claim 2, wherein said coolant supply control means uses the estimated temperature transition of the electric motor and the sensed coolant temperature as input parameters to determine, by fuzzy inference, an amount of operation of the coolant supplying means from the input parameters, operate the coolant supplying means according to the determined amount of operation, and control the amount of coolant supply to the electric motor.

4. The apparatus according to claim 3 wherein said coolant supply control means includes

means for calculating goodness-of-fit values for fuzzy rules based on membership functions from the membership functions for classifying and expressing the respective orders of magnitude of the input parameters, a plurality of fuzzy rules having the respective orders of magnitude of the input parameters in the antecedent part and a plurality of preset values for the amount of operation of said coolant supplying means in the consequent part, and the input parameters, and

means for calculating a weighted average value of the plurality of set values in the consequent part of the fuzzy rules using the calculated goodness-of-fit values as weighting factors in the consequent part of the fuzzy rules to determine the calculated average value as the amount of operation.

5. The apparatus according to claim 3 wherein

the amount of operation defines a corrective value for the amount of coolant supply from said coolant supplying means, and

said coolant supplying means includes means for integrating a series of determined values for the amount of operation to determine the integral as a value to define the amount of coolant supply from said coolant supplying means, and means for controlling the amount of coolant supply according to the calculated integral.

6. The apparatus according to claim 1 wherein the temperature transition of the electric motor estimated by said temperature transition estimating means is a temperature transition of the electric motor in a region of temperature equal to or above a temperature of the electric motor in a steady-state in which the torque of the electric motor is maintained in a predetermined torque range.

7. The apparatus according to claim 1 wherein

the electric motor is controlled according to command values for torque to be produced by the electric motor, and

said temperature transition estimating means estimates the temperature transition of the electric motor based on the torque command values and an average value of the torque command values.

8. The apparatus according to claim 7, wherein said

temperature transition estimating means includes temperature change estimating means for estimating temperature changes of the electric motor per predetermined unit time by fuzzy inference from the torque command values and the average value of the torque command values as input parameters, and

integration means for calculating an integral of the estimated temperature changes as an estimate of the temperature transition of the electric motor.

9. The apparatus according to claim 8, wherein said temperature transition estimating means includes

means for calculating goodness-of-fit values for fuzzy rules based on membership functions from the membership functions for classifying and expressing the respective orders of magnitude of the input parameters, a plurality of fuzzy rules having the respective orders of magnitude of the input parameters in the antecedent part and a plurality of preset values for the temperature changes per unit time in the consequent part, and the input parameters, and

means for calculating a weighted average value of the plurality of set values in the consequent part of the fuzzy rules using the calculated goodness-of-fit values as weighting factors in the consequent part of the fuzzy rules to determine the calculated average value as an estimate of the temperature changes per unit time.

10. The apparatus according to claim 7, further comprising

motor control means for performing d-q vector control of the electric motor according to the torque command values, and

torque command correcting means for correcting the torque command values according to at least the rotational speed of the electric motor,

wherein said temperature change estimating means estimates the temperature transition of the electric motor using the corrected torque command values and an average value of the corrected torque command values, instead of the torque command values and the average value of the torque command values.

11. The apparatus according to claim 8, further comprising

motor control means for performing d-q vector control of the electric motor according to the torque command values, and

torque command correcting means for correcting the torque command values according to at least the rotational speed of the electric motor,

wherein said temperature change estimating means estimates the temperature transition of the electric motor using the corrected torque command values and an average value of the corrected torque command values, instead of the torque command values and the average value of the torque command values.

12. The apparatus according to claim 10, wherein said torque command correcting means corrects the torque command values according to the rotational speed of the electric motor and the power-supply voltage of the electric motor.

13. The apparatus according to claim 11, wherein said torque command correcting means corrects the torque command values according to the rotational speed of the electric motor and the power-supply voltage of the electric motor.