Resolver Offset Correction Using Motor Shaft Torsion Angle
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Solution Overview
Problem
In eco-friendly vehicles, resolver offset corrections are often inaccurate due to torsional deformation of the motor rotor shaft, leading to angular deviations and motor output deviations, which reduce the motor's lifespan and control accuracy.
Innovation Solution
A resolver offset correction device and method that includes a torsion angle compensator to estimate and correct resolver offset deviations based on the torsion angle of the motor rotor shaft, using a torsion angle calculator and map data to perform primary and secondary offset corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resolver offset correction is performed using zero current control in a zero torque period, then offset correction can be performed using d-axis voltage levels, but torsional deformation occurs in the shaft proportional to torque generated, causing angular deviation in the resolver and inaccurate offset correction
Solution Approach 1:
The patent performs resolver offset correction in advance during a zero-torque period before the motor enters normal operation. By completing the correction when no torque is applied, the system eliminates torsional deformation effects during the measurement phase, ensuring accurate offset values are obtained before the shaft experiences torque-induced angular deviations during operation.
Solution Approach 2:
The patent introduces an intermediary approach by using the zero-torque period as a special operational state for correction. This intermediary state allows the system to separate the correction function from normal operation, using a specific condition (zero torque) that eliminates the interfering factor (torsional deformation) while still allowing the motor to be connected and operational.
2Ease of manufacture
If resolver offset correction is performed without considering shaft torsion angle, then correction can be completed in zero torque period, but angular deviation occurs in the resolver mounted on the shaft, causing error in corrected offset
Solution Approach 1:
The system performs offset correction in advance during zero-torque periods before the motor operates under load. This preliminary action ensures that the shaft is in a torsion-free state during measurement, eliminating the need for complex real-time torsion compensation while maintaining high measurement accuracy.
Solution Approach 2:
The patent implements periodic offset correction by utilizing zero-torque periods that occur during motor operation (such as during regenerative braking or coasting phases). The correction is performed intermittently at these specific periods rather than continuously, maintaining accuracy while simplifying the overall system design.
Data Source
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AI summary
A device and method for correcting a resolver offset of an eco-friendly vehicle is provided. The device and method are capable of correcting the resolver offset based on an angle of torsion occurring in a shaft of a motor rotor. Accordingly, the resolver offset is corrected more accurately.