Variable Frequency Shunt Active Power Filter Harmonic Control
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Solution Overview
Problem
Existing shunt active power filters are ineffective in selectively tuning and damping harmonics in variable frequency systems, particularly in the range of 360-800 Hz, leading to spurious output voltages and noise in power circuits.
Innovation Solution
A shunt active power filter system employing a set of resonant regulators in parallel or stacked arrangement, each tuned to specific harmonics, with adjustable gain values to selectively target and dampen undesirable harmonics over a variable frequency range, using the root locus technique to determine optimal gain settings for effective harmonic control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a shunt active power filter is designed to operate on variable frequency sources (360-800 Hz), then the filter can handle a wider range of operating conditions, but the range and amplitude of potential harmonics become significant and difficult to control
Solution Approach 1:
The patent divides the harmonic control into multiple independent resonant regulators, each tuned to specific harmonic frequencies (5th, 7th, 11th, 13th, 17th, 19th harmonics). This segmentation allows each regulator to independently target and dampen specific harmonics generated at variable frequencies, making the overall system effective across the 360-800 Hz range while controlling individual harmonic amplitudes
Solution Approach 2:
The patent implements dynamic gain adjustment for each resonant regulator based on the detected source frequency. The gain values are continuously adapted using the root locus technique to maintain optimal harmonic suppression performance as the operating frequency varies, enabling the filter to effectively handle the wide frequency range while controlling harmonic content
2Reliability
If resonant regulators are used to target specific harmonics in variable frequency systems, then harmonic suppression effectiveness is improved, but the system complexity increases due to multiple tuned regulators and gain adjustment mechanisms
Solution Approach 1:
The patent designs each resonant regulator to serve multiple purposes: they are tuned to specific harmonic frequencies but with adjustable gain values that adapt to the source frequency. This multi-functionality allows a finite number of regulators to effectively handle harmonics across the entire 360-800 Hz range, reducing the need for an excessive number of fixed-frequency regulators while maintaining high suppression effectiveness
3Speed
If gain values are adjusted to rapidly eliminate harmonics, then the speed of harmonic suppression is improved, but stability of the control system may be compromised
Solution Approach 1:
The patent implements a feedback mechanism where the source frequency is continuously detected and used to adjust the gain values of the resonant regulators. This closed-loop control ensures that the gain adjustment is based on actual system conditions, allowing rapid harmonic suppression while maintaining stability through adaptive rather than fixed high-gain control
Solution Approach 2:
The patent dynamically changes the gain parameter of each resonant regulator based on the detected source frequency and root locus analysis. By adjusting the gain values as system parameters change rather than using fixed high gains, the system achieves rapid harmonic elimination speed while preserving control stability across the variable frequency operating range
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
The system effectively eliminates harmonics by creating a notch filter at targeted frequencies, ensuring rapid harmonic suppression and minimizing noise and artifacts in power circuits across a range of source frequencies.
Implementation Method 1
A shunt active power filter system employing a set of resonant regulators in parallel or stacked arrangement, each tuned to specific harmonics
Implementation Method 2
The system effectively eliminates harmonics by creating a notch filter at targeted frequencies
Data Source
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AI summary
Embodiments to systems and methods for tuning the control of a shunt active power filter over a variable frequency. In aspects, a shunt active power filter is provided to filter current harmonics from the output delivered to a dc load via a recitifier. The shunt active power filter control can be configured as a set of resonant regulators connected in a parallel configuration. Each of the resonant regulators can be tuned to dampen or eliminate a particular harmonic, such as, the 5th, 7th, 11th, 13th, 17th, or 19th harmonics. The shunt active power filter can be configured to target those or other harmonics over a range of source voltage frequencies, such as 360 - 800 Hz. The harmonics can be tuned over that or other source frequency ranges by determining the root locus poles of the filter as a function of feedback loop gain.