Current Sensor Offset Compensation in Drive Motor Control
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Solution Overview
Problem
Existing methods for compensating the offset of current sensors in drive motor control units are insufficient in preventing torque ripple and creep surge phenomena, as they cannot accurately adjust for temperature variations and are typically only performed before the vehicle starts moving.
Innovation Solution
A method that involves confirming specific conditions such as the vehicle being stationary and the drive motor torque demand being zero, then stopping current supply to the drive motor and compensating the current sensor offset, using a vehicle control unit to generate a power-off instruction and turning off the insulated gate bipolar transistor, thereby regularly adjusting the current sensor offset during predetermined driving conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If offset compensation is performed only before vehicle start, then device complexity is reduced, but measurement precision deteriorates due to temperature variations during operation
Solution Approach 1:
The patent implements periodic offset compensation by detecting specific conditions (vehicle stopped, motor current zero) and performing compensation at these intervals during operation. This periodic approach maintains measurement precision without requiring continuous compensation, thus avoiding excessive device complexity.
Solution Approach 2:
The system uses feedback by continuously monitoring vehicle operation state and motor current to determine when offset compensation should be performed. This feedback mechanism ensures compensation occurs at appropriate times during operation, maintaining accuracy while managing system complexity.
2Measurement precision
If offset compensation is performed continuously, then measurement precision is improved, but productivity deteriorates due to increased processing time
Solution Approach 1:
Offset compensation is performed periodically only when specific conditions are met (vehicle stopped, motor current zero), rather than continuously. This reduces processing time and maintains productivity while still ensuring measurement precision through regular compensation at critical moments.
Solution Approach 2:
The system performs offset compensation in advance during periods when the vehicle is stopped and motor current is zero, before the next operation phase begins. This preliminary action ensures accuracy is maintained without interrupting subsequent productivity-critical operations.
3Measurement precision
If offset compensation is performed during motor operation, then measurement precision is improved, but object-generated harmful factors worsen due to torque ripple and creep surge
Solution Approach 1:
The system performs offset compensation during periods when the motor is not operating (vehicle stopped, current zero), which is a preliminary anti-action that prevents torque ripple and creep surge from occurring during actual motor operation. By compensating when the motor is idle, the system eliminates the harmful effects that would otherwise be generated during operation.
Solution Approach 2:
The patent converts the idle periods (when vehicle is stopped and motor current is zero) into beneficial opportunities for offset compensation. These periods, which might be considered wasted time, are actually used to improve measurement precision without generating harmful torque ripple or creep surge, thus turning a non-productive state into a useful one.
Data Source
AI summary
Disclosed is a method for setting a current sensor of a vehicle having a drive motor according to an exemplary embodiment of the present invention may include confirming a first condition that a vehicle stops its movement, confirming a second condition that a required torque of a drive motor of a vehicle is 0, stopping a current that is supplied to the drive motor if the first condition and the second condition are satisfied, and compensating offset of the current sensor of a drive motor control unit controlling the drive motor. The offset may be compensated if the first condition and the second condition are satisfied for a predetermined time. Accordingly, an offset of the current sensor is compensated in a predetermined driving condition that the vehicle stops moving and therefore the creep surge and the motor torque ripple that can be generated in the vehicle are prevented.