Parallel Inverters for Solar MPPT Load Balancing
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Solution Overview
Problem
Conventional solar distributed power systems face inefficiencies due to high conduction losses and suboptimal operation of power inverters when converting low voltage from multiple solar panels to standard AC current, as the maximum power point tracking (MPPT) module often operates at a point optimal for only a few panels, leading to reduced overall efficiency.
Innovation Solution
A distributed power system with multiple parallel-connected inverters, each equipped with a control module that autonomously adjusts current draw based on voltage or power input to achieve a power equilibrium, allowing for load balancing and efficient power conversion among the inverters, ensuring optimal operation of each solar panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple solar panels are connected in series to form strings and then connected in parallel to achieve higher current and power output, then the power delivery capability is improved, but the conduction losses increase due to high current (proportional to i²)
Solution Approach 1:
The patent divides the power conversion function into multiple independent inverter modules connected in parallel. Each inverter processes a portion of the total power independently, allowing the system to deliver high power while keeping individual inverter currents lower, thus reducing conduction losses proportional to i² for each module.
2Device complexity
If a single MPPT module is used to track the maximum power point for the entire array, then the system complexity is reduced, but the power conversion efficiency decreases because the MPPT operates at a point optimal for only a few panels
Solution Approach 1:
The patent assigns a dedicated MPPT module to each inverter, creating multiple independent maximum power point tracking systems. Each MPPT independently optimizes the power extraction for its associated inverter and solar panels, ensuring that every panel operates at its optimal power point rather than forcing a compromise average point across the entire array.
Solution Approach 2:
The patent implements local optimization by allowing each inverter-MPPT combination to independently determine and operate at its own optimal working point based on local conditions (panel characteristics, irradiance, temperature). This local quality approach ensures that each segment of the system operates at peak efficiency rather than a centralized average.
3Productivity
If multiple inverters are connected in parallel to share power conversion load, then the power conversion efficiency is improved, but the control complexity increases to achieve proper load balancing
Solution Approach 1:
The patent implements autonomous control where each inverter independently monitors its own input voltage and power conditions, and self-adjusts its operating parameters without requiring complex centralized coordination. Each inverter with its dedicated MPPT autonomously determines its optimal operating point based on local measurements, simplifying the overall control architecture while maintaining efficient load distribution.
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 enables efficient power conversion and load balancing among inverters, maximizing peak power harvesting from each solar panel and reducing overall system inefficiencies, thereby improving the overall efficiency and reliability of the solar power system.
Implementation Method 1
an inverter 104, which converts the direct-current (DC) into alternating-current (AC) having a desired voltage and frequency
Implementation Method 2
The control modules respectively control current drawn by the inverters from the DC input responsive to either the voltage or power of the DC input
Data Source
Figure 1
Figure 1B
Figure 2
AI summary
A distributed power system wherein a plurality of power converters are connected in parallel and share the power conversion load according to a prescribed function, but each power converter autonomously determines its share of power conversion. Each power converter operates according to its own power conversion formula/function, such that overall the parallel- connected converters share the power conversion load in a predetermined manner.