Current Sensor Offset Compensation for Motor Control Stability
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Solution Overview
Problem
Current sensor offsets in hybrid electric vehicles (HEVs) and electric vehicles (EVs) change due to external noise, aging, and temperature variations, leading to motor control instability and pulsation errors if constant initial compensation is applied, destabilizing the entire system.
Innovation Solution
An apparatus and method for continuously recalculating the current sensor offset using a current controller, which calculates the offset when PWM control is discontinued and compensates the motor current detected by the sensor, generating a PWM signal based on the offset-compensated current for stable motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If constant initial offset compensation is applied, then the system is simple to operate, but the motor control stability deteriorates due to offset changes from aging, temperature, and noise
Solution Approach 1:
The patent transitions from static initial offset compensation to dynamic continuous offset compensation. The current sensor offset is continuously calculated and updated during motor operation, allowing the compensation value to adapt to changes caused by aging, temperature variations, and external noise, thereby maintaining motor control stability throughout the system's operational life.
Solution Approach 2:
The patent implements a feedback mechanism where the current sensor offset is continuously monitored and recalculated based on actual current measurements during motor operation. This feedback loop ensures that offset compensation values are continuously updated to reflect current sensor conditions, preventing motor output torque pulsation and maintaining system stability.
2Device complexity
If offset is compensated only at initial driving, then the compensation process is simple, but motor output torque pulsation occurs due to offset drift over time
Solution Approach 1:
The patent implements continuous offset compensation during motor operation rather than a single initial compensation. The offset is continuously calculated and updated, ensuring that compensation remains accurate throughout the motor's operational life and preventing torque pulsation caused by offset drift from aging, temperature changes, and external noise.
Solution Approach 2:
The patent performs offset calculation and compensation in advance during periods when PWM control is discontinued, preparing the compensation value before the next motor operation. This preliminary action ensures that accurate offset compensation is ready when the motor starts, preventing torque pulsation from the outset.
3Reliability
If frequent offset recalculation is performed, then motor control stability is improved, but the control system complexity increases
Solution Approach 1:
The patent performs offset recalculation periodically when PWM control is discontinued, rather than continuously during motor operation. This periodic approach maintains motor control stability by updating offset compensation at appropriate intervals while avoiding the complexity and computational burden of continuous recalculation during active motor control.
Data Source
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AI summary
Provided is an apparatus for compensating offset of a current sensor detecting a motor current supplied by an inverter for PWM (Pulse Width Modulation) control of a motor, the apparatus including a current controller providing a PWM signal generated based on the motor current detected by the current sensor to the inverter, calculating an offset using the motor current detected by the current sensor in response to presence and absence of the PWM control of the motor, or offset-compensating the motor current detected by the current sensor.