Solar Power MPPT Control System for Partial Shade
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Solution Overview
Problem
Conventional MPPT control methods face challenges with local solutions not being the maximum power point, leading to reduced power efficiency and increased costs due to complex algorithms and extensive circuit requirements for each solar cell module, especially under partial shade conditions.
Innovation Solution
A solar power system with a dual control unit configuration that varies output voltage within different widths and compares voltage changes, using a comparison unit to select between hill climbing and search-variable methods based on current variation thresholds, preventing local solutions without excessive circuit complexity or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If optimization algorithms (genetic algorithm, Fibonacci search) are used to avoid local solutions, then power efficiency is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies dynamics by making the search width variable during the hill climbing process. The control unit dynamically adjusts the voltage variation width based on the relationship between current and power values, expanding the search range when improvement is detected and narrowing it when no improvement occurs. This dynamic adjustment allows the system to escape local solutions without requiring complex optimization algorithms, thereby improving power efficiency while maintaining circuit simplicity.
Solution Approach 2:
The patent changes the parameter of search width (voltage variation range) during the control process. By varying the width of voltage changes in the hill climbing method based on detected power improvements, the system adapts its search behavior to avoid local maxima. This parameter change approach replaces the need for complex algorithms like genetic algorithms, resolving the contradiction between power efficiency and device complexity.
2Device complexity
If hill climbing method is used for MPPT control, then device complexity is reduced, but local solutions cause power efficiency to deteriorate
Solution Approach 1:
The patent introduces dynamics into the traditional static hill climbing method by making the search width variable. The control unit adjusts the voltage variation range dynamically based on whether power improvement is detected, allowing the simple circuit to adapt its behavior and escape local solutions, thereby improving power efficiency without increasing device complexity.
Solution Approach 2:
The patent applies preliminary action by expanding the search width before potentially encountering local solutions. When power improvement is detected, the system proactively increases the voltage variation range to explore broader regions of the power-voltage curve, preventing entrapment in local maxima before they become problematic, thus maintaining both circuit simplicity and power efficiency.
3Productivity
If measurement units are added to detect partial shade conditions, then power efficiency is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies self-service by using the existing voltage and power measurements already taken for MPPT control to detect partial shade conditions. The control unit analyzes the relationship between voltage and power values to identify characteristics of partial shading without requiring additional measurement units. This self-diagnostic capability improves power efficiency under partial shade while avoiding increased device complexity.
Solution Approach 2:
The patent makes the existing measurement system multi-functional by using voltage and power detectors not only for MPPT control but also for detecting partial shade conditions. The control unit performs dual functions: optimizing power extraction and detecting shading scenarios, thereby improving power efficiency without adding dedicated measurement devices, resolving the contradiction between functionality and 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
This approach enhances power efficiency by avoiding local solutions and reducing circuit costs, maintaining high performance in steady states and handling partial shade effectively without the need for extensive measurement units.
Implementation Method 1
solar cells
Data Source
AI summary
In a case in which a local solution to current-voltage characteristics is generated by way of a partial shade, it has been difficult to perform control for causing a solar cell to operate at a maximum power point efficiently in terms of power and at a low cost. During steady state operation, an MPPT control unit 1 for performing the normal hill climbing method is selected, and if the change amount of the output current of the solar cell is greater than or equal to a predetermined threshold, an MPPT control unit 2 for increasing the variation width of the output voltage of the solar cell to greater than the hill climbing method is selected. By way of such control, it is possible to achieve both efficient operation in a steady state and avoidance of a local solution to a partial shade at a low cost.