Multi-Level Power Converter With Self-Powered String-Level MPPT
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Solution Overview
Problem
Solar power generation systems with single converters face challenges in tracking the maximum power point for individual solar cell strings due to varying sunlight conditions, and they require additional devices for voltage detection and auxiliary power supply in multi-level structures, which increases complexity and cost.
Innovation Solution
A power conversion device with multiple converters connected to cell strings and auxiliary power supply units using voltages from the cell strings, where each converter is controlled by a single or multi-stage regulator, and a control unit monitors and applies control signals for maximum power point tracking, allowing for linked control and efficient voltage detection across different reference potentials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single converter is used for the entire solar cell module, then the device complexity is reduced, but the maximum power point tracking control for individual cell strings becomes impossible when sunlight conditions differ
Solution Approach 1:
The solar cell module is divided into multiple cell strings, each with its own converter. This segmentation allows each converter to independently perform maximum power point tracking for its respective cell string, even when sunlight conditions differ across the module. The patent shows multiple converters (e.g., 111, 112, 113) connected to different cell strings (131, 132, 133), enabling individualized control while maintaining overall system functionality.
2Adaptability or versatility
If multiple converters with multi-level structure are used for individual cell strings, then the maximum power point tracking for each string is enabled, but the device complexity and material costs increase due to additional voltage detection and auxiliary power supply devices
Solution Approach 1:
The auxiliary power supply unit is designed to perform multiple functions: it generates auxiliary power from cell string voltages and simultaneously provides voltage detection capabilities. The patent shows the auxiliary power supply unit (150) receiving voltages from multiple cell strings and providing both power and detection functions, eliminating the need for separate detection circuits and reducing overall device complexity.
Solution Approach 2:
The auxiliary power supply unit utilizes the voltages already present on the cell strings to generate its own auxiliary power and detection signals, rather than requiring external power sources or separate detection devices. The system serves itself by harvesting energy and control signals from the existing cell string voltages, reducing the need for additional components.
3Device complexity
If the same ground reference is used for solar cell module, DC/DC converter, and controller, then the auxiliary power circuit configuration is simplified, but this approach cannot be applied to multi-level structure MLPE
Solution Approach 1:
Each converter in the multi-level structure has its own local ground reference and auxiliary power supply unit tailored to its specific voltage level and requirements. The patent shows that each converter (111, 112, 113) operates with its own reference potential and auxiliary power supply, allowing the system to adapt to different voltage levels and configurations while maintaining proper grounding and power supply for each component.
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 solution reduces the number of controllers needed, enables efficient maximum power point tracking for each cell string, allows for stable auxiliary power supply, and reduces material costs by using isolated converters and cascaded regulators, while maintaining efficient communication and monitoring capabilities.
Implementation Method 1
an auxiliary power supply unit 150 that generates driving power for the plurality of converters 111 to 113
Data Source
AI summary
A power conversion device according to one embodiment of the present invention comprises: a plurality of converters that are each connected to a plurality of cell strings; and a plurality of auxiliary power supply units for supplying driving power to each of the plurality of converters by using the voltage output from each cell string, wherein the plurality of converters have a multi-level structure.