Multilevel Converter Phase Angle Allocation for Distortion Reduction
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Solution Overview
Problem
The complexity of precisely controlling switching time points in multilevel converters increases with the number of power converters, making it challenging to achieve efficient waveform conversion and reduce high-frequency distortion.
Innovation Solution
A central controller allocates phase angles to sub-units, which create local switching carriers to compare with a reference AC voltage, allowing for precise control of power converter switching points, reducing operational complexity and improving waveform synthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the number of power converters in the multilevel converter is increased, then the high frequency distortion of the output waveform is reduced, but the algorithm complexity for controlling switching time points increases
Solution Approach 1:
The control system is divided into a central controller that generates reference signals and multiple sub-units that independently generate local switching carriers based on allocated phase angles. This segmentation allows each sub-unit to handle switching control independently, reducing the overall algorithm complexity while maintaining precise control of switching time points for multiple power converters
Solution Approach 2:
The system uses phase angle allocation as a key parameter to control switching time points. By changing the phase angle parameters allocated to each sub-unit, the system can precisely control the switching timing of multiple power converters without increasing algorithm complexity, thereby reducing high frequency distortion in the output waveform
2Manufacturing precision
If the number of power converters in the multilevel converter is increased, then the output waveform quality is improved, but the control operation amount increases
Solution Approach 1:
The control operations are segmented between a central controller that performs phase angle allocation and multiple sub-units that independently generate local switching carriers and execute switching control. This distribution of control operations reduces the computational burden on any single controller and enables efficient management of multiple power converters
Solution Approach 2:
The central controller pre-allocates phase angles to each sub-unit before the switching operation begins. This preliminary action allows sub-units to independently generate their switching carriers without real-time coordination overhead, reducing the control operation amount while maintaining precise switching time point control for high quality output waveforms
Data Source
AI summary
A technology is disclosed for controlling switching of power converters included in a power converting system. Phase angles are allocated to a plurality of sub-units corresponding to the power converters, and the respective sub-units create local switching carriers based on the allocated phase angles. The sub-units compare a reference AC voltage with the local switching carriers, and switch the power converters according to the result of the comparison.