Inverter Frequency Segmentation for Harmonic Reduction
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Solution Overview
Problem
Existing power converting apparatuses and photovoltaic modules face challenges in improving the quality of output current, particularly due to inefficiencies in converting DC voltage to AC voltage and managing harmonic current components.
Innovation Solution
The proposed solution involves a power converting apparatus with a tapped inductor boost converter and a controller that operates in multiple switching modes, classifying operation based on constant-voltage periods to ensure a desired AC voltage waveform and reduce harmonic current influence, along with a Module Integrated Converter (MIC) circuit for efficient DC power management within the photovoltaic module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional DC-AC converter is used, then the structure is simple, but the output current quality is poor due to harmonic current components
Solution Approach 1:
The converter is divided into multiple independent full-bridge circuits (first full-bridge circuit and second full-bridge circuit) that operate at different switching frequencies. This segmentation allows each circuit to handle specific frequency components, with the first circuit operating at a lower frequency and the second at a higher frequency, thereby eliminating harmonic current components while maintaining a relatively simple overall structure.
Solution Approach 2:
The patent employs asymmetric clocking where the two full-bridge circuits operate at different switching frequencies (first switching frequency for the first full-bridge circuit and second switching frequency for the second full-bridge circuit). This asymmetric operation prevents harmonic overlap and enables effective elimination of harmonic current components from the output.
2Speed
If switching frequency is increased to improve response speed, then response speed improves, but loss of energy increases due to higher switching losses
Solution Approach 1:
The switching operation is segmented into two frequency domains: a lower first switching frequency for the first full-bridge circuit and a higher second switching frequency for the second full-bridge circuit. This segmentation allows the system to achieve fast response where needed while minimizing switching losses in other portions, optimizing the trade-off between response speed and energy efficiency.
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 enhances the quality of the output current by eliminating harmonic current components and ensuring reliable capacitor operation, while also providing efficient DC voltage conversion and management within the photovoltaic module.
Implementation Method 1
A solar cell among such alternative energy sources has been highlighted as a next-generation cell which directly converts solar energy into electrical energy using a semiconductor device.
Implementation Method 2
a converter for transforming a DC voltage into a pseudo DC voltage
Implementation Method 3
an inverter for converting the pseudo DC voltage into an AC voltage
Data Source
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AI summary
A power converting apparatus and a photovoltaic module are discussed. The power converting apparatus includes a converter including a tapped inductor and a first switch, the converter converting a level of an input direct current (DC) voltage and outputting the level-converted DC voltage, and an inverter including a plurality of switches, the inverter converting the level-converted DC voltage into an alternating current (AC) voltage. The inverter operates separately in a first switching mode where the inverter performs a switching operation at a first frequency for a first period of the converted AC voltage and a second switching mode where the inverter performs a switching operation at a second frequency for a second period of the converted AC voltage, the second frequency being lower than the first frequency.