Motor Disturbance Observer Tuning for Torque Ripple Vibration
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Solution Overview
Problem
Existing motor control systems, including electric power steering systems, struggle to adequately suppress vibrations caused by torque ripple, and this issue is not limited to steering systems but also affects various mechanical devices.
Innovation Solution
A motor control device incorporating a disturbance observer unit that estimates and compensates for disturbances based on motor rotation information, adjusting parameters to match the antiresonance characteristics of the mechanical device, thereby reducing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If torque differential control is performed to suppress vibrations due to torque ripple, then vibrations are partially suppressed, but vibrations cannot be suppressed to a required level
Solution Approach 1:
The control device uses feedback from the mechanical device's response to adjust the command value. The control device calculates a command value, applies it to the motor, and uses the mechanical device's actual response to refine subsequent command values, creating a closed-loop system that progressively reduces vibrations to meet required levels.
Solution Approach 2:
The control device dynamically changes control parameters including command value, frequency, and amplitude based on the mechanical device's response. By adjusting these parameters iteratively, the system optimizes vibration suppression effectiveness beyond what fixed-parameter torque differential control can achieve.
2Reliability
If the command value is increased to overcome disturbance, then the motor can maintain operation under disturbance, but vibrations due to torque ripple are exacerbated
Solution Approach 1:
The control device dynamically adjusts the command value based on real-time conditions rather than using a fixed increased value. The control device iteratively modifies the command value, frequency, and amplitude according to the mechanical device's response, allowing the system to maintain operation under disturbance while minimizing vibrations through adaptive parameter adjustment.
Solution Approach 2:
The control device changes multiple parameters simultaneously including command value magnitude, excitation frequency, and amplitude based on the mechanical device's response characteristics. This multi-parameter adjustment allows the system to overcome disturbance effects while suppressing torque ripple-induced vibrations.
3Adaptability or versatility
If torque differential control is applied to all mechanical devices, then vibration suppression is attempted across different applications, but the complexity of adjusting control parameters increases
Solution Approach 1:
The control device performs self-adjustment by automatically modifying the command value, frequency, and amplitude based on the mechanical device's response. This self-service capability eliminates the need for manual parameter tuning for different mechanical devices, enabling versatile application across various applications while keeping the control system simple to implement.
Solution Approach 2:
The control device is designed with universal functionality to work with different types of mechanical devices. By implementing iterative command value adjustment with automatic parameter modification, the same control strategy can be applied across various applications without requiring application-specific parameter calibration, thus reducing overall system complexity.
Data Source
AI summary
A motor control device controls a motor of a mechanical device. The motor control device includes a command value calculation unit that calculates a command value for controlling the motor, and a disturbance observer unit for estimating a disturbance applied to the mechanical device, based on the command value and rotation information of the motor, and to correct the command value based on the disturbance that is estimated. The disturbance observer unit has parameters that are adjusted to compensate for effects of the disturbance having a specific frequency that is an object of suppression. The parameters are adjusted such that a disturbance, applied to the mechanical device after effects of the disturbance are compensated for, has frequency characteristics corresponding to antiresonance characteristics of the mechanical device.