Torque current comparison for current reasonableness diagnostics in a permanent magnet electric machine
First Claim
1. A method of diagnostics for ascertaining status of an electric machine coupled to a polyphase bus, the method comprising:
- detecting a rotational position of said electric machine with a position encoder coupled to said electric machine;
controlling an inverter comprising a plurality of switching devices, said inverter having an input coupled to a direct current bus and an output coupled to said polyphase bus, said inverter responsive to commands from a controller coupled to said inverter and to said position encoder;
measuring a current from said direct current bus;
capturing a torque current;
calculating a current error establishing a bound limit for said torque current;
comparing said current error value to said bound limit;
determining whether a fault exists by evaluating if said bound limit has been exceeded and generating a current error;
incrementing a fault counter by a first predetermined count if said fault exists;
decrementing said fault counter by a second predetermined count if no fault exists; and
indicating a failure if said fault counter exceeds a predetermined limit.
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Accused Products
Abstract
A method and system for diagnostics and ascertaining status of an electric machine coupled to a polyphase bus. The method and system include: detecting a rotational position with a position encoder coupled to the electric machine; controlling an inverter having an input coupled to a direct current bus and an output coupled to the polyphase bus, where the inverter is responsive to commands from a controller coupled to the inverter and to the position encoder. The method and system further include measuring a current from the direct current bus; capturing a torque current; calculating a current error; establishing a bound limit for the torque current; comparing the current error to the bound limit. The method and system also include: determining whether a fault exists by evaluating if the bound limit has been exceeded; incrementing a fault counter if a fault exists; decrementing a fault counter if no fault exists; and indicating a failure if the fault counter exceeds a predetermined limit.
122 Citations
29 Claims
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1. A method of diagnostics for ascertaining status of an electric machine coupled to a polyphase bus, the method comprising:
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detecting a rotational position of said electric machine with a position encoder coupled to said electric machine;
controlling an inverter comprising a plurality of switching devices, said inverter having an input coupled to a direct current bus and an output coupled to said polyphase bus, said inverter responsive to commands from a controller coupled to said inverter and to said position encoder;
measuring a current from said direct current bus;
capturing a torque current;
calculating a current error establishing a bound limit for said torque current;
comparing said current error value to said bound limit;
determining whether a fault exists by evaluating if said bound limit has been exceeded and generating a current error;
incrementing a fault counter by a first predetermined count if said fault exists;
decrementing said fault counter by a second predetermined count if no fault exists; and
indicating a failure if said fault counter exceeds a predetermined limit. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A diagnostics system for ascertaining status of an electric machine, the system comprising:
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said electric machine coupled to a polyphase bus, including a position encoder coupled to said electric machine to detect rotational position;
an inverter having an input coupled to a direct current bus, and an output coupled to said polyphase bus, responsive to commands from a controller;
said controller coupled to said inverter and to said position encoder;
a sensor to detect a current from said direct current bus;
said controller capturing a torque current;
said controller calculating a current error said controller establishing a bound limit for said torque current;
said controller comparing said current error value to said bound limit;
said controller determining whether a fault exists by evaluating if said bound limit has been exceeded and generating a current error;
said controller incrementing a fault counter by a first predetermined count if said fault exists;
said controller decrementing said fault counter by a second predetermined count if no fault exists;
said controller providing a fault indication to declare a failure if said fault counter exceeds a predeterrnined limit. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A storage medium encoded with a machine-readable computer program code for ascertaining status of an electric machine coupled to a polyphase bus, said storage medium including instruction for causing a controller to implement a diagnostics method comprising:
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detecting a rotational position of said electric machine with a position encoder coupled to said electric machine;
controlling an inverter comprising a plurality of switching devices, said inverter having an input coupled to a direct current bus and an output coupled to said polyphase bus, said inverter responsive to commands from a controller coupled to said inverter and to said position encoder;
measuring a current from said direct current bus;
capturing a torque current;
calculating a current error establishing a bound limit for said torque current;
comparing said current error value to said bound limit;
determining whether a fault exists by evaluating if said bound limit has been exceeded and generating a current error;
incrementing a fault counter by a first predetermined count if said fault exists;
decrementing said fault counter by a second predetermined count if no fault exists; and
indicating a failure if said fault counter exceeds a predetermined limit. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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23. A computer data signal embodied in a carrier wave for ascertaining status of an electric machine coupled to a polyphase bus, said data signal comprising code configured to cause a controller to implement a diagnostics method comprising:
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detecting a rotational position of said electric machine with a position encoder coupled to said electric machine;
controlling an inverter comprising a plurality of switching devices, said inverter having an input coupled to a direct current bus and an output coupled to said polyphase bus, said inverter responsive to commands from a controller coupled to said inverter and to said position encoder;
measuring a current from said direct current bus;
capturing a torque current;
calculating a current error establishing a bound limit for said torque current;
comparing said current error value to said bound limit;
determining whether a fault exists by evaluating if said bound limit has been exceeded and generating a current error;
incrementing a fault counter by a first predetermined count if said fault exists;
decrementing said fault counter by a second predetermined count if no fault exists; and
indicating a failure if said fault counter exceeds a predetermined limit. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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Specification