Cascade DC-AC Converter Control for PV Arrays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for feeding solar energy into the grid, such as micro-inverters and power optimizers, face inefficiencies and high costs due to multiple conversion stages and sensitivity to partial shading and panel mismatches in photovoltaic arrays.
Innovation Solution
A method of controlling DC/AC converters in a cascade configuration, where each converter receives input from a photovoltaic panel and produces output AC, allowing individual control based on input current and voltage, with optional energy storage for redundancy and dynamic adjustment, and the use of a single conversion stage to maximize efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple conversion stages (micro-inverters or power optimizers) are added to each PV panel to enable individual tuning and improve performance under partial shading, then adaptability and reliability are improved, but device complexity and cost increase
Solution Approach 1:
The patent merges multiple conversion functions into a single centralized DC/AC converter. Instead of having separate micro-inverters or power optimizers at each panel, all PV panels are connected in series to a single converter that performs both DC/DC boosting and DC/AC conversion in one integrated stage, eliminating redundant components while maintaining individual panel tuning capability through independent voltage control
Solution Approach 2:
The single DC/AC converter is designed to perform multiple functions: it acts as both a DC/DC boost converter for voltage matching and a DC/AC converter for grid interface. This multi-functional design replaces what would traditionally require separate conversion stages at each panel, reducing overall system complexity while maintaining adaptability
2Adaptability or versatility
If multiple conversion stages are used to enable individual panel control, then adaptability under partial shading is improved, but conversion efficiency deteriorates
Solution Approach 1:
By combining DC/DC boosting and DC/AC conversion into a single stage, the patent eliminates the energy losses associated with multiple conversion stages. The single converter achieves both voltage matching and AC conversion in one process, reducing cumulative efficiency losses while maintaining the ability to individually tune panel voltages for optimal performance under partial shading conditions
3Adaptability or versatility
If DC/DC boost converters are added to adapt voltage levels in series-connected panels, then voltage matching is improved, but device complexity and cost increase
Solution Approach 1:
The patent integrates the DC/DC boost converter functionality directly into the single DC/AC converter. The boost converter stage is combined with the DC/AC conversion stage, eliminating the need for separate DC/DC converters at each panel or in the input stage. This integrated approach maintains voltage adaptation capability while reducing the total number of converters in the system
Data Source
AI summary
A method of controlling a plurality of DC/AC converters in cascade configuration, each being arranged to receive an input direct current and voltage from a respective photovoltaic panel and to deliver an electric output. The method includes receiving information representing at least one of frequency, phase, amplitude and harmonics of a required AC, and receiving information on the input direct current and voltage to each one of the plurality of DC/AC converters. Based on the received information, each one of the plurality of DC/AC converters is individually controlled in such manner that the combined output from the plurality of DC/AC converters produces an AC matching the required AC.