PV Sub-Module Controller Circuit for Partial Shading Power Harvest
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Solution Overview
Problem
Photovoltaic (PV) power optimizers struggle to effectively manage power distribution across PV systems due to shading issues, where partial shading of any PV module affects the entire array's performance, leading to reduced efficiency and energy output.
Innovation Solution
A controller circuit for PV sub-modules that includes a power harvest controller, voltage limit controller, power mode control, multiplexer, and switching converter circuits, which generate and route gate control signals to optimize DC string voltage, manage output voltage, and switch between power harvest and voltage limit modes to maximize energy production even under partial shading conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PV power optimizers run at the string level to find maximum power point, then the entire string's power point is optimized, but partial shading of any PV module affects the operating power point of the entire PV array
Solution Approach 1:
The patent divides the PV array into individually controllable modules, each with its own power optimizer. This segmentation allows each module to independently track its maximum power point, preventing shading on one module from affecting the entire array's performance. Each module operates autonomously, isolating the impact of partial shading to only the affected module rather than the whole string.
2Device complexity
If a single power optimizer controls the entire PV string, then system complexity is reduced, but the ability to adapt to local shading conditions is lost
Solution Approach 1:
The control function is segmented and distributed to individual module-level controllers rather than centralized in a single string-level optimizer. Each controller independently manages its associated PV module, enabling localized adaptation to shading conditions while maintaining overall system coordination through standardized communication protocols.
Solution Approach 2:
Each PV module is equipped with its own power optimizer that can independently detect and respond to local shading conditions. This local quality approach allows each module to have customized control parameters and operating characteristics tailored to its specific environmental conditions, rather than being constrained by uniform string-level control.
3Area of stationary object
If PV modules are physically spread over large surface area, then energy capture area is increased, but shading effects propagate across the entire array
Solution Approach 1:
The large PV array is segmented into multiple independently controlled modules, each with its own power optimizer. This segmentation isolates shading losses to individual modules rather than allowing them to propagate across the entire array, thereby reducing total energy loss despite the large overall surface area.
Solution Approach 2:
The patent converts the potential harm of partial shading into a benefit by using module-level power optimizers to identify and compensate for shaded modules. The system detects reduced output from shaded modules and adjusts operating parameters to maximize power extraction from unshaded modules, thereby converting the shading problem into an opportunity for optimized power management.
Data Source
AI summary
A controller circuit for a PV sub-module includes a power harvest controller circuit, a voltage limit controller circuit, a power mode control circuit, a multiplexer circuit, and a switching converter circuit. The power harvest controller circuit, including a first PV voltage input, a ceiling reference input, a floor reference input, and a first gate control output. The voltage limit controller circuit, including a first output voltage feedback input, a pulse width reference input, and a second gate control output. The power mode control circuit, including a second output voltage feedback input, a mode reference input, and a mode selection output. The multiplexer circuit, including a first gate control input, a second gate control input, a mode selection input, and a third gate control output. The switching converter circuit, including a second PV voltage input, a third gate control input, and a DC voltage output.