Motor Current Sensor Fault Isolation Using Zero-Current Offsets
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Solution Overview
Problem
Conventional troubleshooting methods for current sensors in motors cannot accurately identify faulty sensors without stopping the motor, leading to potential misjudgments and continuous operation disruptions.
Innovation Solution
A system comprising three current sensors and a controller that controls the motor's phase currents to zero and identifies faulty sensors by determining the current sensor with the largest difference from zero and the sensor closest to zero, allowing for accurate identification without stopping the motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional troubleshooting methods use three phase current sensing results to determine sensor abnormality, then safety requirements are met, but accurate identification of faulty sensors cannot be achieved leading to misjudgments
Solution Approach 1:
The system performs preliminary calibration to obtain offset values for each current sensor before normal operation. These offset values are stored and used during troubleshooting to compensate for sensor biases, enabling accurate faulty sensor identification without misjudgments.
Solution Approach 2:
The system changes the operating parameter by setting motor current to zero during troubleshooting mode. This creates a specific test condition where all current sensors should read zero (after offset compensation), making it easy to identify faulty sensors that deviate from this expected value.
2Measurement precision
If the motor is stopped for testing every current sensor carefully, then accurate faulty sensor identification can be achieved, but continuous operation is disrupted
Solution Approach 1:
The system performs preliminary calibration to obtain offset values for each current sensor before normal operation. These offset values are stored and used during troubleshooting to compensate for sensor biases, enabling accurate faulty sensor identification without misjudgments.
Solution Approach 2:
The system uses the existing current sensors and control capabilities to perform self-diagnosis. By controlling motor current to zero and comparing sensor readings against stored offset values, the system identifies faulty sensors without external testing equipment or motor shutdown.
3Reliability
If three current sensors are added to sense three phase currents for abnormal detection, then safety requirements are met, but device complexity increases
Solution Approach 1:
The three current sensors serve multiple functions: they monitor motor operation during normal operation and perform self-diagnosis during troubleshooting mode. The same sensors used for motor control also detect faults, eliminating the need for separate diagnostic sensors.
Solution Approach 2:
The system uses the existing current sensors and control capabilities to perform self-diagnosis. By controlling motor current to zero and comparing sensor readings against stored offset values, the system identifies faulty sensors without external testing equipment or motor shutdown.
Data Source
AI summary
The present disclosure provides a troubleshooting system for current sensors including a motor, three current sensors and a controller. The three current sensors respectively sense three phase currents of the three-phase current of the motor to obtain three current sensing values. The controller is configured to control the three-phase current of the motor. When the sum of the three current sensing values is greater than a threshold, the controller controls the three phase currents to be zero, and a first offset sensor and a current offset are obtained. When the sum of the three current sensing values equals the current offset, a second offset sensor is obtained. If the first offset sensor and the second offset sensor are the same current sensor, the controller outputs a warning signal, if the first offset sensor and the second offset sensor are different current sensors, the controller controls the motor to stop operating.