Method and device for monitoring the operation of a motor
First Claim
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1. A method of monitoring the operation of a motor-driven system, comprising the steps of:
- sensing a current drawn by the motor at a preselected time after starting the motor;
comparing the sensed current to previously determined minimum and maximum current threshold values which define a range of currents;
determining that a malfunction has occurred in the system when the current is sensed outside the range of currents;
adjusting at least one of the minimum and maximum current threshold values as a function of the sensed current; and
storing the adjusted threshold values to be used the next time the preceding steps are carried out.
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Abstract
In a method and device for monitoring the operation of a motor, the current drawn by the motor is sensed a preselected time after a peak of current is sensed. This sensed current is then compared to both a minimum and a maximum current threshold value to determine whether the sensed current is inside or outside the range of currents defined by the minimum and maximum current threshold values. The minimum and/or maximum current threshold values are dynamically adjusted as a function of the comparison.
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Citations
11 Claims
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1. A method of monitoring the operation of a motor-driven system, comprising the steps of:
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sensing a current drawn by the motor at a preselected time after starting the motor; comparing the sensed current to previously determined minimum and maximum current threshold values which define a range of currents; determining that a malfunction has occurred in the system when the current is sensed outside the range of currents; adjusting at least one of the minimum and maximum current threshold values as a function of the sensed current; and storing the adjusted threshold values to be used the next time the preceding steps are carried out. - View Dependent Claims (2, 3, 4)
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5. A device for monitoring the operation of a motor-driven system, comprising:
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means for sensing a current drawn by the motor at a preselected time after starting the motor; means for comparing the sensed current to previously determined minimum and maximum current threshold values which define a range of currents; means for determining that a malfunction has occurred in the system when the current is sensed outside the range of currents; means for adjusting at least one of the minimum and maximum current threshold values as a function of the sensed current; and means for storing the adjusted threshold values for subsequent use. - View Dependent Claims (6, 7, 8)
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9. A method of monitoring the operation of a motor-driven system, comprising the steps of:
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sensing a current drawn by the motor; comparing the sensed current to a previously determined minimum current threshold value; timing an interval during which the sensed current is below the minimum current threshold value; comparing the interval to a preselected maximum time threshold value; determining that a malfunction has occurred in the system if the interval is greater than the preselected maximum time threshold value;
adjusting the minimum current threshold value as a function of the sensed current; and
storing the adjusted minimum current threshold value to be used the next time the preceding steps are carried out.
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10. A method of monitoring the operation of a motor-driven system, comprising the steps of:
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sensing a peak current drawn by the motor; comparing the sensed peak current to a previously determined maximum current threshold value; counting a number of times that the peak current transitions above the maximum current threshold value within a preselected interval of time; comparing the count to a preselected maximum count threshold value; determining that a malfunction has occurred in the system if the count is greater than the preselected maximum count threshold value;
adjusting the maximum current threshold value as a function of the sensed current; and
storing the adjusted maximum current threshold value to be used the next time the preceding steps are carried out. - View Dependent Claims (11)
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Specification