Intra-Module DC-DC Converter for PV String Power Mismatch
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Solution Overview
Problem
Photovoltaic systems face significant power losses due to power mismatching between solar cells caused by partial shading, which existing centralized power conversion methods are unable to effectively address, especially at the submodule and string levels.
Innovation Solution
Incorporating intra-module DC-DC converters with a non-isolated, high gain boost converter topology, operating at high frequency (400-500 kHz) and capable of wide input voltage range (10-30V), to manage power distribution at the string level within PV modules, reducing power mismatches and improving efficiency under varying lighting conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a centralized power converter is used for a system with a large number of modules, then the system structure is simplified, but power mismatching between solar cells causes significant power loss
Solution Approach 1:
The patent divides the centralized power conversion system into multiple distributed DC-DC converters, each serving specific PV modules or strings. This segmentation allows independent power management for each module, enabling optimal power extraction even when individual modules experience partial shading, thereby reducing overall power loss while maintaining manageable system complexity through modular architecture
Solution Approach 2:
The patent implements local DC-DC converters at the module or string level, allowing each local unit to independently manage its power conversion. This local quality approach enables tailored power management for each module based on its specific operating conditions (e.g., shading patterns), maximizing power extraction from each module while maintaining overall system efficiency
2Loss of energy
If distributed power management techniques are implemented at the PV module level, then power efficiency is improved under partial shading conditions, but device complexity increases
Solution Approach 1:
The patent designs the DC-DC converter with a universal topology that can be applied across multiple PV modules or strings using identical circuit configurations. This multi-functionality allows the same converter design to handle various shading patterns and operating conditions, improving power efficiency while avoiding the complexity of designing custom solutions for each module
Solution Approach 2:
The patent employs a DC-DC converter topology with adjustable voltage gain through parameter changes (such as duty cycle control and capacitor ratios). This allows the converter to adapt its conversion ratio dynamically based on input voltage variations and loading conditions, maintaining high efficiency across different operating points while using a single standardized hardware platform
3Power
If high static gain voltage multipliers are used, then voltage conversion ratio is increased, but circuit complexity increases
Solution Approach 1:
The patent implements a nested voltage multiplier structure where capacitor-charger circuits are integrated within the DC-DC converter topology. The voltage multiplier stages are embedded nested within the main converter circuit, allowing high voltage gain to be achieved through cascaded capacitor charging stages without requiring separate complex multiplier circuits, thus increasing conversion ratio while controlling circuit complexity
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 solution enhances power output and efficiency under partial shading conditions by minimizing power mismatches between solar cells, reducing energy losses, and enabling a compact, cost-effective distributed power management system for PV modules.
Implementation Method 1
Photovoltaic (PV) panels, herein also referred to as PV units or PV modules, have long been argued to be a very attractive solution for future clean energy resource
Implementation Method 2
said multiplier stage comprising two capacitors CM1, CM2, each capacitor respectively connected to a diode DM1, DM2, and whereby said diodes DM1, DM2 of the at least one multiplier cell are adapted to charge the multiplier capacitors CM1, CM2 with a charge voltage VM
Data Source
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AI summary
The present invention relates to an intra-module DC-DC power converter and a Photovoltaic (PV) module comprising same. The switching frequency of said intra-module DC-DC power converters may be 500 k Hz. The PV module may have a controller and a plurality of switches for allowing each individual string of said PV module to be connected to one corresponding DC-DC converter, or for allowing two or more strings of said module to be connected in series and to apply the voltage of the combined string to a single DC-DC converter. The input voltage range of the DC-DC converters may be 10V to 30V, and the output voltage range may be 120V. The DC-DC converters may be connected in series or in parallel. Multiple such PV panels may be connected in a DC-grid.