Grid-Tied Inverter Filter Resonance Control Under Overload
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Solution Overview
Problem
Conventional inverter circuits face instability due to excessive resonance frequencies when switching frequencies are reduced to meet power demands, leading to complex control processes and poor adaptability, especially during short-time overloads.
Innovation Solution
A grid-tied inverter apparatus with a controller that adjusts the resonance frequency of a filter circuit through different resonant branches by varying the switching frequencies of power switching transistors based on output current values, ensuring the resonance frequency meets stability requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the switching frequency of power switching transistors is reduced to meet power requirements during overload, then the power supply capability is improved, but the resonance frequency of the filter circuit becomes excessively high, leading to system instability
Solution Approach 1:
The filter circuit is divided into multiple resonant branches with different resonance frequencies. Each branch contains switching elements that can be independently controlled. When the main switching frequency is reduced during overload, specific resonant branches are activated to provide auxiliary resonance paths that maintain the overall resonance frequency within the stable range (less than 1/4 of the switching frequency), thus preventing system instability while enabling reduced switching frequency operation.
2Adaptability or versatility
If conventional feedforward adjustment control is used to adapt to load changes, then the output voltage can be adjusted, but the control process becomes complex and control time increases
Solution Approach 1:
The resonant branches are designed to automatically activate based on the operating conditions. When the switching frequency is reduced, the circuit topology naturally provides alternative resonance paths without requiring complex control algorithms. The control system simply needs to switch between predefined resonance modes, significantly simplifying the control process while maintaining good load adaptability.
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
The solution provides fast and simple control, enhancing system stability and loading capacity while maintaining efficient power supply, even under overload conditions.
Implementation Method 1
the filter circuit includes a plurality of resonant branches that include an inductor unit and a plurality of resonant units connected in parallel
Data Source
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AI summary
This application provides a grid-tied inverter apparatus and a grid-tied control method. The inverter apparatus includes an inverter circuit, a controller, and a filter circuit. The controller is configured to adjust switching frequencies of a plurality of power switching transistors based on an output current value of the inverter apparatus, to adjust a resonance frequency of the filter circuit through different resonant branches, so that the resonance frequency meets a grid-tied requirement. In this application, when the switching frequencies of the plurality of power switching transistors in the inverter circuit are reduced due to overload of a power supply system, resonance may be produced through different resonant branches, to adjust the resonance frequency of the filter circuit in a timely manner, so as to ensure that the resonance frequency of the filter circuit meets a requirement for system stability. A response is fast, and a control method is simple, so that system stability and security are improved, and applicability is high.