Adaptive Harmonic Mitigation in Power Converters
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Solution Overview
Problem
Conventional power conversion systems, particularly those with active front-end converters, face challenges in effectively controlling total harmonic distortion (THD) and specific harmonics due to limitations in existing harmonic reduction techniques such as selective harmonic elimination (SHE) and hardware-based input filter circuits, which are costly and insufficient for overall THD control.
Innovation Solution
The implementation of adaptive harmonic mitigation (AHM) techniques in power converters, which use a switching angle generator to provide rectifier switching angles based on source and load harmonics, allowing for real-time or lookup table-based computation of AHM angles to control both the magnitudes and phase angles of harmonic components, thereby improving harmonic control beyond conventional PWM schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If hardware-based input filter circuits are provided, then harmonic control is improved, but system cost increases
Solution Approach 1:
The patent replaces physical hardware filter circuits with an adaptive control system that uses switching angle adjustment to mitigate harmonics, substituting mechanical/electrical filtering components with a control-based solution that achieves harmonic reduction without additional passive components
Solution Approach 2:
The system changes the switching angles of the power converter based on detected harmonic conditions, using parameter adjustment of the control signals to achieve harmonic mitigation instead of adding physical filter components, thereby reducing system cost while maintaining effective harmonic control
2Ease of operation
If conventional PWM switching control is used, then rectifier operation is simple, but harmonic control capability is limited
Solution Approach 1:
The patent enhances conventional PWM by making the switching angles dynamic and adaptive rather than fixed, allowing the system to maintain operational simplicity while improving harmonic control capability through real-time adjustment based on background harmonic detection
Data Source
AI summary
Power conversion systems with active front end converters for example motor drives and power generation systems for distributed energy sources are presented with adaptive harmonic minimization for grid-tie converters for minimized or reduced total harmonic distortion in the line current spectrum including the source harmonic current, the load harmonics and the PWM harmonics.