Multi-Source PV Inverter Buck Converter Topology
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Solution Overview
Problem
Traditional single-phase photovoltaic (PV) inverters require two stages for power conversion, leading to inefficiencies due to high-frequency switching losses and the need for multiple switching devices, and they struggle to maintain peak efficiency when drawing power from multiple sources.
Innovation Solution
The proposed PV inverter topology eliminates the intermediate DC link, reduces high-frequency switching devices, and employs adaptive digital control and ripple current cancellation techniques to minimize losses and maximize efficiency, using a buck-boost converter with a dual capacitor bank and soft-switching methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional two-stage power conversion is used, then power conversion function is achieved, but conversion efficiency deteriorates due to high-frequency switching losses
Solution Approach 1:
The patent combines the DC-DC conversion and DC-AC inversion functions into a single integrated inverter stage, eliminating the separate DC link and intermediate DC-DC converter. This merging removes the second source of high-frequency switching losses while maintaining the dual functionality of voltage matching and grid synchronization, directly resolving the efficiency problem caused by two-stage conversion.
2Ease of operation
If multiple switching devices are used for power conversion, then conversion functionality is achieved, but device complexity increases
Solution Approach 1:
The inverter stage performs multiple functions simultaneously: it converts DC to AC, provides grid synchronization, enables bidirectional power flow, and handles voltage matching. By making the inverter universal and multi-functional, the patent eliminates the need for separate DC-DC converter components and control systems, reducing overall device complexity while maintaining full conversion capability.
3Reliability
If fixed switching frequency control is used, then control stability is achieved, but adaptability to varying operating conditions deteriorates
Solution Approach 1:
The patent implements dynamic control where the inverter operates in different modes (grid-tied inversion, standalone inversion, charging, discharging) based on real-time operating conditions and grid requirements. The control system dynamically adjusts switching patterns, duty cycles, and operational parameters to maintain stability across varying sources (PV arrays, batteries, fuel cells) while adapting to grid conditions, thus achieving both reliability and versatility.
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 achieves higher conversion efficiency by reducing switching losses, minimizing the number of high-frequency switching devices, and ensuring peak efficiency across varying conditions, including multiple input sources, with improved power factor and reduced conduction losses.
Implementation Method 1
Photovoltaic (PV) cells generate direct current (DC) power with the level of DC current being dependent on solar irradiation
Data Source
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AI summary
A photovoltaic (PV) inverter system (100) operates continuously in a buck converter mode to generate a sum of full wave rectified sine wave currents at a current node common to a plurality of buck converters in response to a plurality of full wave rectified sine wave currents (120), (122), (124), (126) generated via the plurality of buck converters. The PV inverter system (100) increases the level of the voltage sourcing each buck converter when a corresponding DC power source voltage (104), (106), (108), (110) is lower than the instantaneous voltage of a utility grid connected to the PV inverter system (100).