Synchronous Buck-Boost Inverter for Photovoltaic Grid Connection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing circuit arrangements for converting time-variable DC output voltage from photovoltaic systems into AC voltage for grid connection face challenges in maintaining constant input voltage for inverters, minimizing line losses, and operating photovoltaic systems at maximum power point, while requiring efficient and autonomous operation.
Innovation Solution
A circuit arrangement with parallel sub-circuit arrangements featuring a synchronous converter (buck-boost inverter) and a control circuit that automatically activates step-up or step-down converter functions based on output voltage thresholds, allowing for autonomous operation and efficient voltage regulation, including MPP tracking for photovoltaic systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the output voltage of photovoltaic systems is transmitted directly to the inverter circuit, then line losses are minimized, but the input voltage at the inverter circuit cannot be kept constant
Solution Approach 1:
The circuit arrangement divides the voltage conversion function into multiple independent partial circuit arrangements, each with its own synchronous converter. This segmentation allows each converter to independently regulate voltage while maintaining direct connection to the photovoltaic system, thus minimizing line losses while ensuring constant input voltage to the inverter circuit.
Solution Approach 2:
The synchronous converters dynamically adjust their conversion ratio parameter based on the instantaneous output voltage of the photovoltaic system. By changing the conversion ratio, the converters maintain a constant output voltage to the inverter circuit while adapting to the variable input voltage from the photovoltaic system, thereby resolving the contradiction between minimizing line losses and maintaining voltage constancy.
2Stability of the object's composition
If a higher-level control logic continuously manages the voltage conversion, then voltage regulation is achieved, but the device complexity and control requirements increase
Solution Approach 1:
Each partial circuit arrangement is equipped with its own control circuit that autonomously manages the synchronous converter operation. The control circuits independently monitor their respective photovoltaic system output and adjust the converters without requiring continuous intervention from a higher-level control logic, thereby reducing overall system complexity while maintaining effective voltage regulation.
Solution Approach 2:
The control function is segmented and distributed to individual control circuits in each partial circuit arrangement. This decentralization eliminates the need for a complex centralized control logic, as each control circuit independently handles voltage regulation for its associated synchronous converter, simplifying the overall control architecture.
3Use of energy by moving object
If the photovoltaic system operates at maximum power point, then energy efficiency is maximized, but the output voltage varies over time
Solution Approach 1:
The synchronous converters dynamically adjust their conversion ratio parameter in response to the varying output voltage from the photovoltaic system operating at MPP. This parameter adjustment allows the converters to maintain a stable output voltage to the inverter circuit while the photovoltaic system continues to operate at its maximum power point, thus preserving energy efficiency while achieving voltage stability.
4Power
If multiple sub-circuit arrangements are connected in parallel, then the system can handle higher power loads, but the coordination and control becomes more complex
Solution Approach 1:
Each parallel-connected partial circuit arrangement operates autonomously with its own control circuit and synchronous converter. The arrangements independently regulate their output voltage and current without requiring complex coordination protocols, allowing the parallel configuration to scale power handling capacity while maintaining simple individual control 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 solution ensures stable and efficient conversion of photovoltaic system output voltage to AC, minimizing line losses and maintaining high efficiency, enabling operation at maximum power point without requiring continuous higher-level control logic, thus enhancing operational safety and efficiency.
Implementation Method 1
a synchronous converter (buck-boost inverter) with a first capacitor connected between the first terminals of a switching stage and a series connection of two capacitors at their second terminals
Implementation Method 2
a synchronous converter (buck-boost inverter) with a first capacitor connected between the first terminals of a switching stage and a series connection of two capacitors at their second terminals
Data Source
Figure 1
Figure 2~3
AI summary
The circuit arrangement comprises one or multiple parallel connected partial circuit arrangement (1) for power supply to an inverter circuit (9) which is connected with a power network (90). A supply line is provided between a capacitor (30) and a connection (42). A direct current source (6) is provided for supplying a control circuit (7) for controlling of synchronous converter (4). An independent claim is also included for a method for controlling a circuit arrangement.