Motor Control Device Variable Bandstop Filter Center Frequency
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Solution Overview
Problem
Conventional motor control devices with variable bandstop filters experience fluctuations in control signals when changing center frequencies, leading to mechanical shocks and reduced processing precision, especially when prioritizing speedy detection of natural vibrations.
Innovation Solution
A motor control device with a frequency component extracting unit, frequency detection unit, frequency step size setting unit, center frequency changing unit, and variable bandstop filter, which sets a smaller secondary frequency step size for incremental adjustments to the center frequency, reducing fluctuations in control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a large frequency step size is used to prioritize speedy detection of natural vibrations, then detection speed is improved, but fluctuations in control signals increase causing mechanical shocks
Solution Approach 1:
The patent segments the frequency adjustment process into two distinct stages: a first frequency step size for rapid initial detection, and a second (smaller) frequency step size for precise final adjustment. This segmentation allows the system to benefit from both fast detection and smooth control signal transitions, resolving the contradiction between speed and mechanical shock reduction.
Solution Approach 2:
The patent dynamically adjusts the frequency step size based on the detection phase. During initial detection, a larger step size is used for speed, while during final adjustment, a smaller step size is applied to minimize fluctuations. This dynamic adaptation resolves the contradiction by optimizing the parameter for each specific operational phase.
2Measurement precision
If the center frequency of the variable bandstop filter is changed by adding or subtracting a change value all at once, then the center frequency can be changed to coincide with the natural frequency, but fluctuations in the control signal increase
Solution Approach 1:
The patent segments the frequency adjustment into multiple incremental steps using a second frequency step size that is smaller than the first. Instead of making a single large adjustment, the center frequency is changed through multiple smaller steps, which reduces control signal fluctuations while still achieving accurate coincidence with the natural frequency.
Solution Approach 2:
The patent applies partial action by using a smaller second frequency step size for the final adjustment phase. This partial adjustment approach prevents excessive changes in the control signal while still achieving the necessary frequency alignment, thereby reducing mechanical shocks and control signal fluctuations.
3Device complexity
If a bandstop filter with fixed center frequency is used, then the device complexity is reduced, but it cannot suppress natural vibrations when the natural frequency changes with driven member position
Solution Approach 1:
The patent implements a variable bandstop filter where the center frequency can be dynamically adjusted based on the driven member position and detected natural frequency. This dynamic capability allows the filter to adapt to changing operating conditions while maintaining vibration suppression effectiveness, resolving the contradiction between simplicity and adaptability.
Solution Approach 2:
The patent incorporates a feedback mechanism where the natural frequency is continuously detected and used to adjust the center frequency of the bandstop filter. This feedback loop ensures the filter remains effective across different operating positions without requiring complex manual reconfiguration, balancing simplicity with adaptability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces fluctuations in control signals and mechanical shocks, enhancing processing precision by allowing for smoother adjustments of the center frequency, even when using larger frequency step sizes for speedy detection of natural vibrations.
Implementation Method 1
a variable bandstop filter configured to input the control signal, and configured such that the center frequency is variable by the center frequency changing unit in order to output the control signal after a frequency component corresponding to the natural frequency after the change is removed from the control signal
Implementation Method 2
a predetermined frequency step size for use in extracting a frequency component included in a control signal in the conventional motor control device is set to a relatively large value (e.g. 10 Hz) when speedy detection of natural vibrations is prioritized to accurate detection of natural vibrations
Data Source
AI summary
A frequency component extracting unit (15) extracts a frequency component included in a control signal at a first frequency step size. A frequency detection unit (16) detects, from the extracted frequency component, a frequency corresponding to a natural frequency of a target object constituted of a motor (3) and a driven member (4). A frequency step size setting unit (17) sets a second frequency step size smaller than the first frequency step size. A center frequency changing unit (18) increases or decreases a center frequency of a variable bandstop filter (13) at the second frequency step size in order to output a control signal after the variable bandstop filter (13) removes a frequency component corresponding to the natural frequency after the change from the control signal.