Modular Multilevel Power Converter Harmonic Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional multilevel power converters face challenges in reducing harmonic distortion and increasing the number of voltage levels without increasing module count, which leads to higher costs and efficiency losses.
Innovation Solution
The method involves grouping energy storage devices into sets and controlling them to maintain different potentials, allowing for increased voltage levels and reduced harmonic distortion without adding additional modules, using a control algorithm to manage the charging and coupling of energy storage devices in a modular multilevel converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the number of modules within the converter is increased to increase the number of voltage levels, then the harmonic distortion is reduced, but the cost of the converter increases and the overall efficiency decreases due to additional switching losses
Solution Approach 1:
The patent applies parameter changes by operating energy storage devices at different potential levels (first potential vs second potential) rather than uniform potentials. This allows the converter to generate multiple voltage levels using the same number of modules, thereby reducing harmonic distortion without increasing device complexity or switching losses.
Solution Approach 2:
The patent implements dynamic operation by sequentially coupling and decoupling energy storage devices between different potential states based on control signals. The control unit dynamically switches devices between first and second potentials to generate the desired stepped waveform, enabling flexible voltage level generation without additional hardware.
2Manufacturing precision
If the number of modules within the converter is increased to increase the number of voltage levels, then the output waveform more closely approximates a sinusoid, but the cost of the converter increases
Solution Approach 1:
The patent changes the operational parameter of energy storage devices from uniform potential to differentiated potentials (first and second potentials). This parameter change enables the generation of multiple discrete voltage levels that create a stepped waveform closely approximating a sinusoid, achieving high waveform accuracy without increasing the number of modules.
Solution Approach 2:
The patent segments the operation of energy storage devices into different potential groups (first potential devices and second potential devices). By controlling subsets of devices at different potentials and sequentially coupling/decoupling them, the system generates multiple voltage steps that improve waveform approximation without requiring additional modular components.
3Object-generated harmful factors
If additional switching components are added to increase the number of voltage levels, then the harmonic distortion is reduced, but the switching losses increase which reduce the overall efficiency
Solution Approach 1:
The patent reduces switching losses by changing the operational parameter of existing switching components from uniform potential switching to differentiated potential switching. The control unit intelligently selects which energy storage devices to couple or decouple at any given time, minimizing the number of switching operations required while still generating multiple voltage levels and reducing harmonic distortion.
Solution Approach 2:
The patent enables existing energy storage devices to serve multiple functions by operating them at different potentials. The same switching components that would traditionally only switch uniform potentials now dynamically switch devices between first and second potentials, allowing the system to reduce harmonic distortion without adding new switching components or incurring additional switching losses.
Data Source
Figure 1a
Figure 1b
Figure 2
AI summary
A power conversion method comprising: charging a plurality of energy storage devices of a power converter from an input power source; and sequentially coupling and decoupling energy storage devices of the plurality of energy storage devices to an output. Charging the plurality of energy storage devices comprises maintaining at least two of the plurality of energy storage devices at substantially different potentials.