Shared-Storage Inverter Isolation Against Backflow Currents
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Solution Overview
Problem
Inverters in photovoltaic power grid systems face challenges in maintaining stable power supply due to intermittent direct current from sources like photovoltaic cells, leading to potential damage from backflow currents during short-circuits and increased hardware costs from individual energy storage systems for each inverter unit.
Innovation Solution
The inverter apparatus incorporates protection units with diodes and power switches that isolate short-circuited units, sharing a common energy storage system, and uses direct current-direct current converters to manage voltage and prevent surge currents, allowing for parallel connection of inverter units to reduce hardware costs and prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If each inverter unit is connected to an individual energy storage system, then the reliability of each inverter unit is improved, but the hardware cost and device complexity increase significantly
Solution Approach 1:
The patent merges multiple individual energy storage systems into a single shared energy storage system that serves all inverter units. The protection units are also shared across multiple inverter units, creating a centralized resource allocation architecture that reduces hardware costs while maintaining system reliability through shared resources.
Solution Approach 2:
The patent segments the protection function into dedicated protection units that can be selectively activated for different inverter units. Each protection unit can independently isolate faulty inverter units while allowing healthy units to continue operating, providing reliability through modular protection without requiring duplicate energy storage systems for each unit.
2Device complexity
If inverter units are connected in parallel to share energy storage, then hardware cost is reduced, but the risk of backflow current damage during short-circuits increases
Solution Approach 1:
The patent introduces protection units as intermediary components between the shared energy storage system and individual inverter units. These protection units include isolation switches and protection devices that act as mediators to prevent harmful backflow currents from propagating between inverter units while allowing normal energy flow during healthy operation.
Solution Approach 2:
The protection units are configured to detect short-circuit conditions and activate isolation switches before backflow current can cause damage to other inverter units. This preliminary protective action blocks the harmful current path while maintaining the shared energy storage architecture's cost benefits.
3Reliability
If protection units isolate short-circuited inverter units, then the reliability of healthy inverter units is improved, but the device complexity increases
Solution Approach 1:
The protection units are designed as universal components that can protect multiple different inverter units through a standardized interface. Each protection unit can selectively connect to and protect any inverter unit it is assigned to, reducing overall system complexity by using identical protection hardware for different protection targets rather than custom protection circuits for each unit.
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 configuration ensures stable power supply by isolating short-circuited units, preventing damage, and reducing hardware costs through shared energy storage, while maintaining efficient operation and flexibility in fault detection and voltage management.
Implementation Method 1
Each of the plurality of protection units includes a diode and a power switch. An anode of the diode is configured to connect to a direct current source unit, a cathode of the diode is connected to a direct current input terminal of an inverter unit
Implementation Method 2
an anode of the diode is connected to a cathode of the power switch, and the cathode of the diode is connected to an anode of the power switch
Data Source
AI summary
An inverter apparatus is disclosed in this application, which includes a plurality of protection units and a plurality of inverter units. For any protection unit, when a voltage at an input terminal of the protection unit is greater than a voltage at an output terminal of the protection unit, a path between the input terminal and the output terminal of the protection unit is in a forward conducted state; when the voltage at the output terminal of the protection unit is greater than the voltage at the input terminal voltage of the protection unit, the path between the input terminal and the output terminal of the protection unit is in a reverse cut-off state; and when a control terminal of the protection unit receives a first trigger signal, the path between the input terminal and the output terminal of the protection unit is in a reverse conducted state.