Inverter Harmonic Reduction via Switching Frequency Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inverters used in power generation devices generate undesired harmonics that strain the network and consumers, and existing solutions to mitigate these harmonics are either complex or costly, such as requiring multiple inverters with precise phase control or high switching frequencies that increase power loss.
Innovation Solution
Operating the inverter with multiple switching frequencies and adjusting the ratio of operating times between these frequencies based on harmonic levels to optimize harmonic reduction, using a model that incorporates various parameters like current, voltage, and grid impedance to control harmonic generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the switching frequency of the inverter is increased above 10kHz, then the proportion of harmonics in low frequency ranges is reduced and existing impedances cause stronger damping, but the switching power loss increases and the inverter heats up more, limiting power delivery
Solution Approach 1:
The inverter is operated with multiple switching frequencies in a periodic manner, switching between different frequencies (e.g., 10kHz and 15kHz) over time. This periodic variation in switching frequency allows the system to maintain lower average harmonic levels while managing switching power loss, as the harmonics are distributed across different frequency ranges rather than concentrated at a single high frequency
Solution Approach 2:
The switching frequency parameter is dynamically changed between multiple values (e.g., 10kHz, 15kHz, 20kHz) based on operating conditions and harmonic requirements. By adjusting the switching frequency parameter rather than fixing it at a single high value, the system can optimize the balance between harmonic reduction and power loss minimization
2Object-generated harmful factors
If multiple inverters are operated with precise phase control to eliminate harmonics by destructive interference, then harmonic-free current feed-in is achieved, but the system complexity and cost increase due to requiring several inverters and complicated higher-level controllers
Solution Approach 1:
Instead of using multiple inverters as proposed in prior art, the invention segments the switching frequency operation within a single inverter. The inverter alternates between different switching frequencies (e.g., 10kHz for 60% of the time and 15kHz for 40% of the time), achieving harmonic reduction through frequency segmentation rather than spatial segmentation with multiple inverters
Solution Approach 2:
The invention achieves the effect of multiple inverters with different phase relationships by copying the harmonic reduction principle through frequency modulation. Rather than physically implementing multiple inverters with complex phase control, a single inverter copies the beneficial effect by varying its switching frequency, simplifying the controller architecture while maintaining harmonic performance
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
The invention relates to a method for operating a current generation device comprising an inverter, to a computer program product for controlling an inverter, to an apparatus for controlling a current generation device comprising an inverter and to a corresponding current generation device. The problem of proposing a method for operating a current generation device comprising an inverter with which the proportion of harmonics is limited in a simple manner such that the specifications of the grid operator are adhered to and nevertheless an optimum power output is provided, is achieved by virtue of the fact that the inverter can be operated at at least two different switching frequencies, wherein the ratio of the operating duration of the inverter at a first switching frequency to the operating duration of the inverter at at least one further switching frequency is selected depending on at least one manipulated variable, and the proportion of harmonics occurring is selected as a manipulated variable.