Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Electrical signal parameter measurement system
Reexamination Certificate
2001-02-20
2004-07-06
Barlow, John (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Electrical signal parameter measurement system
Reexamination Certificate
active
06760669
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to electric motor drive controls and, more particularly to a method and system of reducing inefficiencies in an internal permanent magnet motor using fuzzy logic.
BACKGROUND OF THE INVENTION
Interior permanent magnet systems have been receiving a great deal of attention in electric drive applications, because of their higher power density and efficiency. However, one requirement of electric drive applications concerns the need for an optimized propulsion system. This is due to the fact that electric drive applications use battery, or other electric, power sources. If optimized propulsion systems are not being used, a per mile charge of the electric drive application will be reduced, thus affecting the efficiency of the electric drive.
While some systems have been proffered to optimize the propulsion of an electric drive application, none have utilized the principles of fuzzy logic and control to arrive at a means for reducing the loss of the application, thereby increasing efficiency. In conventional loss minimization controllers, large, multi-dimensional look-up tables are required. Because of the fixed-step changes of the control variable, a relatively long time is required to search for the minimum power point, thus increasing the time to achieve optimization of the propulsion system. Additionally, once the system reaches a minimum power point, the controller oscillates around that point to find the fixed-step change of the variable. This does not necessarily achieve and optimum flux level, and may inhibit efficiency.
However, the usage of fuzzy logic, based on efficiency optimization, causes the search time for the optimal flux to be reduced. This is due to the adaptive nature of the fuzzy logic controller. As a result, the step size of the control variable will be reduced, as the system approaches a minimum power point. Furthermore, once the minimum power point has been achieved, the controller preferably oscillates around that point with almost a negligible step change of the control variable, thus retaining a truly optimum flux level.
Accordingly it would be desirable to have a method and system for reducing loss in an interior permanent magnet drive system that overcomes the above disadvantages.
SUMMARY OF THE INVENTION
One aspect of the present invention provides for a method of reducing loss in an interior permanent magnet drive system. In accordance with this aspect, a current input DC link power value is calculated. The current input DC link power value is then compared with a previous input DC link power value. A change in input DC link power value is determined from this comparison. A flux decrement value is calculated. The flux decrement value is based on the change in input DC link power value. A stator current value is generated. The stator current value is based on the flux decrement value. Finally, the stator flux is reduced, based on the stator current value.
Another aspect of the present invention provides for a computer usable medium for storing a program for reducing loss in an interior permanent magnet drive system. In accordance with this aspect, computer readable program code calculates a current input DC link power value. The current input DC link power value is then compared with a previous input DC link power value by the computer readable program code. A change in input DC link power value is determined from this comparison by the computer readable program code. A flux decrement value is calculated. The flux decrement value is based on the change in input DC link power value. A stator current value is generated by the computer readable program code. The stator current value is based on the flux decrement value. Finally, the stator flux is reduced by the computer readable program code, based on the stator current value.
Another aspect of the present invention provides for a system for reducing loss in an interior permanent magnet drive system. In accordance with this aspect, a current input DC link power value is calculated by a calculating means. The current input DC link power value is then compared with a previous input DC link power value by a comparing means. A change in input DC link power value is determined from this comparison by a determining means. A flux decrement value is calculated by a calculating means. The flux decrement value is based on the change in input DC link power value. A stator current value is generated by a generating means. The stator current value is based on the flux decrement value. Finally, the stator flux is reduced by a reduction means, based on the stator current value.
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O'Meara Thomas P.
Patel Nitinkumar R.
DeVries Christopher
General Motors Corporation
Lau Tung
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