Electric Motor Current Sensor Offset Compensation
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Solution Overview
Problem
The existing electric motor control systems face challenges in accurately measuring and compensating for DC offset values, leading to reduced control performance due to the distortion of current measurements caused by the small DC current required for operating the current sensor, which limits the ability to update offset values during motor operation.
Innovation Solution
A device and method that include an inverter, a current sensor, and a control unit capable of sensing and compensating for offset values by comparing and updating first and second offset values obtained at different times, allowing for real-time compensation of DC offsets in the current sensors attached to the electric motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current sensor measures current flowing in the electric motor, then the current measurement is obtained, but the measurement precision deteriorates due to DC offset distortion
Solution Approach 1:
The system performs preliminary measurement of offset current values during initialization or idle periods before actual motor operation. These pre-measured offset values are stored and used for compensation during motor operation, allowing the system to eliminate measurement errors before they affect control precision.
Solution Approach 2:
The control unit continuously monitors current measurements and uses the stored offset values to compensate for DC offset distortion in real-time. The system compares measured current values with expected values and adjusts control signals to eliminate the effect of offset currents, maintaining accurate current control despite sensor imperfections.
2Productivity
If the electric motor operates continuously, then productivity is improved, but the ability to update offset values deteriorates
Solution Approach 1:
Offset current values are measured and stored in advance during initialization or when the motor is idle, before continuous operation begins. This preliminary measurement ensures accurate offset compensation is available from the start of motor operation without requiring interruptions to continuous operation.
Solution Approach 2:
The system periodically updates offset values during idle periods or transitions in motor operation, such as when the motor stops or changes operating modes. This periodic updating ensures offset compensation remains accurate over time while allowing continuous motor operation during productive periods.
3Reliability
If offset compensation is performed in real-time, then control performance is improved, but device complexity increases
Solution Approach 1:
Offset current values are measured and stored in advance during initialization or idle periods. These pre-measured offset values are then applied during motor operation without requiring complex real-time measurement and calculation systems, simplifying the control architecture while maintaining compensation effectiveness.
Solution Approach 2:
The control unit automatically applies the stored offset values to compensate for measurement errors without requiring external intervention or complex additional hardware. The system uses its existing processing capabilities to perform the compensation calculations and adjust control signals autonomously.
Data Source
AI summary
A device for controlling an electric motor is provided. The device includes: an inverter supplying a current to an electric motor; a current sensor sensing a current supplied from the inverter to the electric motor; and a control unit enabling the current to be supplied from the inverter to the electric motor, obtaining first and second offset values sensed from the current sensor at a plurality of times, comparing the plurality of offset values obtained, and updating the first offset value to the second offset value according to a result of comparing the offset values.