Modular String Inverter Hot-Swapping for Scalable PV Systems
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Solution Overview
Problem
Existing photovoltaic (PV) inverter systems face inefficiencies and scalability limitations, particularly in matching DC power from PV modules to AC demands, leading to underutilization of inverters and increased costs due to the need for large centralized units.
Innovation Solution
A modular string inverter system that allows for hot swapping and selective activation/deactivation of inverters, sharing a common DC bus, and independent control of each inverter to optimize power conversion efficiency and match DC/AC ratios dynamically, enabling flexible and scalable AC outputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large centralized inverters are used to meet peak AC demands, then AC power output capability is improved, but inverter utilization efficiency deteriorates due to underutilization during low-demand periods
Solution Approach 1:
The patent divides the inverter system into multiple modular string inverters that can operate independently. Each inverter processes DC power from specific PV modules and converts to AC power, allowing individual inverters to be sized appropriately for their DC input rather than requiring one oversized centralized inverter. This segmentation enables each inverter to operate at optimal utilization levels while collectively meeting peak AC demands.
2Productivity
If multiple fixed-ratio inverters are deployed, then power conversion capability is improved, but system flexibility deteriorates due to inability to dynamically match DC/AC ratios
Solution Approach 1:
The patent implements dynamic DC/AC ratio matching by allowing the system to adjust the operational status of individual string inverters based on real-time DC power availability and AC demand conditions. The controller can selectively activate or deactivate inverters to optimize the overall DC/AC ratio, transforming a static system into a dynamic one that adapts to changing conditions rather than being constrained by fixed inverter configurations.
3Reliability
If inverters are permanently connected to the grid, then system reliability is improved, but scalability deteriorates due to inability to easily add or remove inverters
Solution Approach 1:
The patent creates a modular inverter architecture where each string inverter is an independent, self-contained unit with its own DC input, AC output, and control system. This segmentation allows inverters to be hot-swapped or dynamically connected/disconnected without affecting the operation of other inverters in the system, enabling easy scalability while maintaining continuous reliable operation through redundancy and load distribution across multiple independent units.
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 overall conversion efficiency, extends inverter durability, and reduces costs by allowing precise matching of power outputs to demand, improving system reliability and flexibility, especially in utility-scale applications.
Implementation Method 1
These inverters use principles of varying magnetic and electric fields to convert a DC voltage and current from a PV cell of the PV module or other DC source to an AC voltage and current for downstream application
Data Source
AI summary
A multi-inverter system with at least a string of inverters sharing a DC bus and outputting to a shared AC bus. Inverters are hot-swappable and configured to be turned on or off during powered cycles. Central control may comprise reducing power point tracking redundancies or promoting other operational changes at individual inverters of a group.