Traction Motor Torque Ripple Compensation via Disturbance Observer
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Solution Overview
Problem
Existing methods to reduce torque ripple in electric traction motors of electric vehicles either increase costs and reduce power density or fail to accurately account for manufacturing variability and varying operating conditions, leading to persistent noise and vibration issues.
Innovation Solution
A method that estimates and compensates for spatially dependent disturbance torque using motor current and position sensors to modify the motor operation, thereby reducing torque ripple by negating the estimated disturbance torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If motor design is modified to minimize torque ripple production, then torque ripple is reduced, but motor costs increase and power density decreases
Solution Approach 1:
The patent changes the operational parameters of the motor control system by introducing a disturbance torque observer that estimates and compensates for torque ripple in real-time. Instead of modifying physical motor design parameters, the system adjusts control parameters (current commands, torque references) based on observed disturbance torque, thereby reducing torque ripple without increasing manufacturing complexity or cost.
Solution Approach 2:
The patent replaces mechanical design modifications with a control-based solution. Rather than physically altering motor components to reduce torque ripple, the system uses software-based disturbance observation and compensation through current control, substituting mechanical complexity with electronic control intelligence.
2Object-generated harmful factors
If pre-calibration is performed to reduce torque ripple, then some torque ripple reduction is achieved, but manufacturing variability and varying operating conditions are not accounted for
Solution Approach 1:
The patent implements a feedback mechanism through the disturbance torque observer that continuously monitors motor operation and adapts to actual conditions. The observer uses real-time measurements of motor current and position to estimate disturbance torque, which then feeds back into the control system for continuous compensation. This closed-loop approach automatically adapts to manufacturing variability and changing operating conditions without requiring re-calibration.
Solution Approach 2:
The patent transitions from static pre-calibration to dynamic real-time compensation. The disturbance torque observer continuously updates its estimates during motor operation, allowing the system to adapt dynamically to varying operating conditions and manufacturing variations. This dynamic approach replaces fixed pre-calibration values with live, condition-specific compensation.
3Object-generated harmful factors
If extensive pre-calibration routine is implemented, then torque ripple reduction may be improved, but it cannot accurately and consistently reduce torque ripple in varied operating conditions
Solution Approach 1:
The patent enables the control system to self-adjust and self-compensate for torque ripple without external intervention or pre-calibration. The disturbance torque observer automatically identifies and compensates for torque ripple across all operating conditions through real-time observation and adaptation, making the system self-sufficient and consistently effective without requiring extensive external calibration routines.
Data Source
AI summary
Torque ripple produced by a traction motor of an electric vehicle when the motor produces torque from a motor current is compensated for by modifying operation of the motor according to a difference between an expected position of the motor to produce a desired torque from the current and the actual position of the motor when producing torque from the current.