Motor Control Apparatus Notch Filter Optimization
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Solution Overview
Problem
Existing motor control apparatuses face challenges in maximizing the velocity control band due to phase delays and instability caused by notch filters, especially when adjusting filter parameters, leading to reduced control band and requiring trial-and-error methods.
Innovation Solution
A motor control apparatus that calculates torque commands and includes a velocity control unit, current control unit, oscillation instruction unit, filter unit, and amplitude evaluation unit to optimize filter parameters by causing controlled oscillations and evaluating amplitude ratios, allowing for automatic selection of optimal filter settings without trial-and-error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a notch filter is used to reduce vibration at resonance frequency, then vibration is reduced, but phase delay occurs in low frequency band causing degradation in stability of velocity control
Solution Approach 1:
The invention dynamically adjusts the notch frequency of the filter based on the detected resonance frequency of the mechanical system. Instead of using a fixed notch frequency, the system continuously adapts the filter parameters to match the actual resonance characteristics, allowing effective vibration suppression while maintaining stability across varying operating conditions
Solution Approach 2:
The invention implements a feedback mechanism where the resonance frequency is detected from the mechanical system's response and used to adjust the notch filter parameters. The system monitors the vibration characteristics and automatically tunes the filter to suppress resonance while preserving low-frequency stability, eliminating the need for manual trial-and-error adjustment
2Object-affected harmful factors
If notch filter parameters are manually adjusted to suppress vibration, then vibration is reduced, but trial-and-error operation is required and control band cannot be maximized
Solution Approach 1:
The invention enables the system to automatically tune its own filter parameters by detecting the resonance frequency from the mechanical system's response and adjusting the notch filter accordingly. The system performs self-diagnosis and self-adjustment without requiring external operator intervention, eliminating trial-and-error operations and maximizing the velocity control band automatically
3Object-affected harmful factors
If the depth and width of notch filter are increased to improve attenuation, then vibration suppression is enhanced, but velocity control band is reduced
Solution Approach 1:
The invention dynamically changes the filter parameters (notch frequency, depth, and width) based on the detected resonance characteristics and operating conditions. Instead of using fixed aggressive attenuation parameters that limit the control band, the system adapts the parameter values to achieve optimal balance between vibration suppression and maintaining a wide velocity control band across different operating states
Data Source
AI summary
A motor control apparatus includes: an oscillation instruction unit outputting an oscillation instruction signal; a filter unit performing filtering processing having frequency characteristic defined by a filter parameter; an oscillation forcing unit configuring a control loop in an oscillation period together with the filter unit, a current control unit, a motor, and a velocity calculation unit and causing the control loop to oscillate during the oscillation period in which the oscillation instruction signal is in the on-state; an amplitude evaluation unit acquiring, as an evaluation value, the amplitude ratio of an input signal to an output signal of the oscillation forcing unit when the control loop oscillates; and a filter adjustment unit comparing evaluation values provided when filter parameter candidates are set in the filter unit sequentially, selecting one of the filter parameters achieving a smaller evaluation value, and setting the selected filter parameter in the filter unit.