Repetitive Controller Frequency Selection Module
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Solution Overview
Problem
Conventional repetitive controllers reduce the stability margin of control systems by amplifying harmonics at medium and high frequencies, failing to effectively cancel only specific harmonics as required in electric and electronic systems.
Innovation Solution
A repetitive controller with a particular frequency selection and passing module is introduced, which includes a frequency selection module or a frequency selection and phase shift module, connected in series with the internal model section, periodic delay module, and compensation module, allowing only selected harmonics to be canceled by configuring large gains at specific frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional repetitive controller with ideal internal model is used, then all integer harmonic components can be cancelled, but the large gain at medium and high frequencies reduces the stability margin of the control system
Solution Approach 1:
The patent segments the frequency spectrum by introducing a frequency selection module that divides harmonics into different frequency ranges (low frequency range including fundamental wave and low-order harmonics, and high frequency range including medium and high-order harmonics). This allows different gain characteristics to be applied to different frequency segments, canceling specific harmonics while limiting gain at other frequencies to maintain stability.
Solution Approach 2:
The patent applies local quality by configuring large gain only at specific frequency points where harmonics need to be canceled (such as 3rd, 5th, and 7th harmonics), while maintaining limited gain at other frequencies. This localized gain configuration enables precise harmonic cancellation without the excessive gain that would compromise system stability across the entire frequency spectrum.
2Manufacturing precision
If conventional repetitive controller amplifies all harmonics, then comprehensive harmonic cancellation is achieved, but the control performance requirements cannot be met due to reduced stability margin
Solution Approach 1:
The patent implements dynamic gain adjustment through the frequency selection module and compensation module, where the gain characteristic is dynamically adapted based on frequency. The controller provides high gain at specific harmonic frequencies for effective cancellation, while automatically limiting gain at other frequencies to maintain stability margin, thus dynamically optimizing both cancellation effectiveness and system reliability.
Solution Approach 2:
The patent changes the gain parameter as a function of frequency by introducing the frequency selection module. Instead of using a uniform gain across all frequencies, the system modifies the gain parameter selectively at different frequency points, achieving high gain at harmonic frequencies for cancellation while maintaining lower gain elsewhere to preserve stability and reliability.
3Manufacturing precision
If repetitive controller cancels all integer harmonics, then complete harmonic removal is achieved, but it cannot meet the requirement of canceling only specific harmonics at particular frequencies
Solution Approach 1:
The patent segments the harmonic spectrum into different frequency ranges using the frequency selection module. It specifically identifies and processes target harmonics (such as 3rd, 5th, and 7th harmonics) separately from other frequency components, enabling selective cancellation of specific harmonics while preserving or differently treating other frequency components, thus achieving both precision and frequency selectivity.
Solution Approach 2:
The frequency selection module acts as an intermediary between the error signal and the compensation module. It selectively passes specific frequency components (target harmonics) to the compensation module for cancellation, while filtering out or differently processing other frequency components. This intermediary function enables precise control over which harmonics are canceled, achieving both cancellation precision and frequency adaptability.
Data Source
AI summary
A repetitive controller, a control method thereof and a feedback control system are disclosed. The repetitive controller includes an internal model section, a periodic delay module and a compensation module. An input quantity is input into the repetitive controller via an input terminal of the internal model section; the internal model section, the periodic delay module and the compensation module are connected in series. The repetitive controller further includes a particular frequency selection and passing module, connected in series with the internal model section, the periodic delay module and the compensation module or configured on a forward path of the internal model section. In the repetitive controller of the disclosure, a particular frequency selection and passing module is incorporated such that only the harmonic at the selected frequency are filtered out, thereby realizing the function of removing the harmonic at the particular frequency.