Inverter Switching Frequency Control via Power Distribution Graph
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Solution Overview
Problem
The existing inverter control methods for grid-tied photovoltaic power generating systems face inefficiencies due to low control accuracy and large errors in adjusting the switching on/off frequency of power switching transistors, which hinder the improvement of conversion efficiency.
Innovation Solution
An inverter control method that involves acquiring a power distribution line graph with predefined switching on/off frequencies, determining the current operating area based on input voltage and output power, and adjusting the switching frequency to match the corresponding preset frequency, thereby improving control efficiency and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the switching on/off frequency of the power switching transistor is adjusted only according to the output power of the inverter, then the loss of the power switching transistor can be reduced when output power is relatively small, but a relatively large error is caused and control efficiency is low
Solution Approach 1:
The control method segments the input voltage and output power parameters into discrete areas on the power distribution line graph. Each area corresponds to a specific switching frequency, allowing the system to select from multiple predefined frequency options rather than using a single frequency or simple power-based adjustment. This segmentation enables more precise matching of switching frequency to actual operating conditions.
Solution Approach 2:
The invention transitions from one-dimensional control (frequency adjustment based solely on output power) to two-dimensional control by introducing input voltage as an additional dimension. The power distribution line graph plots both input voltage and output power, creating a comprehensive operating space where switching frequency is determined by the combination of both parameters, significantly improving control accuracy.
2Loss of energy
If the switching on/off frequency is dynamically adjusted according to output power, then loss reduction is achieved at low power levels, but control efficiency remains low due to large errors
Solution Approach 1:
The power distribution line graph with multiple areas and corresponding switching frequencies is pre-established based on theoretical calculations and optimal operating points. This preliminary preparation allows the controller to quickly lookup and select the appropriate frequency without complex real-time calculations, improving control efficiency while maintaining accurate frequency selection for loss reduction.
Solution Approach 2:
The controller continuously monitors the actual input voltage and output power, compares the current operating point with the pre-established power distribution line graph, and dynamically adjusts the switching frequency accordingly. This closed-loop feedback mechanism ensures the inverter operates at optimal efficiency points while maintaining high control responsiveness.
Data Source
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AI summary
Embodiments of the present invention disclose an inverter control method, apparatus, and system. The method in the embodiments of the present invention includes: obtaining a frequency distribution curve of an inverter switch according to an output power and an input voltage that are of an inverter; when an area to which the inverter belongs is a first area and the inverter switch works at a second frequency, switching the inverter switch to a first frequency; and when the area to which the inverter belongs is a second area and the inverter switch works at the first frequency, switching the inverter switch to the second frequency. In the embodiments of the present invention, whether a working frequency of an inverter switch needs to be changed is determined according to an output power and an input voltage, which improves control efficiency, thereby effectively improving conversion efficiency of an inverter.