Method and system for detecting a failed current sensor in a three-phase machine
First Claim
1. A method of detecting a failed current sensor on an electric machine having a plurality of phases, comprising:
- measuring a phase current of each phase of the electric machine using a current sensor;
calculating an open circuit threshold value based on at least one of the measured phase currents;
determining if an absolute value of a sum of the phase currents of the electric machine is below the determined open circuit threshold value;
identifying a failed current sensor by determining which of the phase currents is approximately zero, if the sum of the phase currents of the electric machine is not below the determined open circuit threshold value; and
estimating the phase current for the failed current sensor by determining a phase current value for the failed current sensor that, when added to the phase currents of the remaining current sensors, makes the sum of all the phase currents equal to approximately zero.
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Accused Products
Abstract
A method of detecting one or more failed current sensor and estimating a phase current for the failed current sensor on a three-phase machine is disclosed. The method may include detecting one or more failed current sensor by determining if an absolute value of a sum of the phase currents of the motor is below an open circuit value. The method may also include determining which phase currents are approximately zero, for each phase current associated with each phase of the motor, if the sum of the phase currents of the motor is not below the open circuit value. The method may further include estimating the phase current for the failed current sensor by determining the phase current value for the failed current sensor, that when added to the phase currents of the remaining current sensors, will make the sum of all the phase currents equal to approximately zero.
30 Citations
19 Claims
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1. A method of detecting a failed current sensor on an electric machine having a plurality of phases, comprising:
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measuring a phase current of each phase of the electric machine using a current sensor; calculating an open circuit threshold value based on at least one of the measured phase currents; determining if an absolute value of a sum of the phase currents of the electric machine is below the determined open circuit threshold value; identifying a failed current sensor by determining which of the phase currents is approximately zero, if the sum of the phase currents of the electric machine is not below the determined open circuit threshold value; and estimating the phase current for the failed current sensor by determining a phase current value for the failed current sensor that, when added to the phase currents of the remaining current sensors, makes the sum of all the phase currents equal to approximately zero. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for detecting a failed current sensor on an electric machine, comprising:
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at least one electric machine having a plurality of phases; at least one sensor deployed per each phase of the at least one electric machine and configured to measure a phase current of that phase of the at least one electric machine; and a controller electrically coupled to the at least one electric machine, the controller configured to; determine if an absolute value of a sum of the phase currents of the at least one electric machine is below an open circuit threshold value; delay for a first time period after determining if the absolute value of the sum of the phase currents of the at least one electric machine is below the open circuit threshold value; after the fist delay period, identify a failed current sensor by determining which of the phase currents is approximately zero, if the absolute value of the sum of the phase currents of the at least one electric machine is not below the open circuit threshold value; estimate the phase current for the failed current sensor by determining a phase current value for the failed current sensor that, when added to the phase currents of the remaining current sensors, makes the sum of all the phase currents equal to approximately zero. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A machine, comprising:
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a power source; at least one electric machine having a plurality of phases; a current sensor associated with each phase of the at least one electric machine and configured to measure a phase current of that phase of the at least one electric machine; and a controller electrically coupled to the at least one electric machine, and the controller configured to; determine if an absolute value of a sum of the measured phase currents of the at least one electric machine is below an open circuit threshold value; identify a failed current sensor by determining which of the phase currents is approximately zero, if the absolute value of the sum of the phase currents of the at least one electric machine is not below the open circuit threshold value; estimate the phase current for the failed current sensor by determining a phase current value for the failed current sensor that, when added to the measured phase currents of the remaining current sensors, makes the sum of all the phase currents equal to approximately zero; use the estimated phase current for the failed current sensor to monitor or control performance of the at least one electric machine; determine if the absolute value of the sum of the measured phase currents of the at least one electric machine is below the open circuit value and if the measured phase current of the failed current sensor is greater than approximately zero; and if the absolute value of the sum of the measured phase currents of the at least one electric machine is below the open circuit value and the measured phase current of the failed current sensor is greater than approximately zero; discontinue using the estimated phase current of the failed current sensor for controlling or monitoring the at least one electric machine; and resume using the measured phase current of the failed current sensor for controlling or monitoring the at least one electric machine. - View Dependent Claims (17, 18, 19)
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Specification