Coupled-Inductor Multilevel Inverter for Low-Harmonic AC Output
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Solution Overview
Problem
Multilevel inverters with increased output voltage levels require more complex controllers and additional components, leading to higher harmonic distortion reduction, but this complexity and component count pose challenges in design and efficiency.
Innovation Solution
A power converter circuit with a multilevel inverter topology that includes a series connection of capacitors and switches, controlled by a controller using PWM signals to balance currents and prevent harmonic distortion, while also incorporating relays for safety and grid protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the number of output voltage levels is increased to reduce harmonic distortion, then the smoothness of output voltage is improved, but the device complexity increases due to more switches and components
Solution Approach 1:
The inverter is divided into multiple independent modular units, each capable of generating specific voltage levels. These modules can be independently controlled and combined to achieve the desired multilevel output, reducing the complexity of controlling a single large inverter while maintaining low harmonic distortion.
Solution Approach 2:
The patent implements a hierarchical control structure where individual module outputs are nested and combined through coupling inductors to form the final multilevel output. This nested arrangement allows lower-level voltage components to be systematically integrated into higher-level voltage synthesis, achieving smooth output waveforms with reduced harmonic content.
2Reliability
If the number of output voltage levels is increased to improve voltage smoothness, then the quality of output voltage is improved, but the controller complexity increases
Solution Approach 1:
The control function is segmented and distributed across multiple independent controllers, each managing a specific modular unit. This distributed control approach reduces the complexity of any single controller while collectively achieving precise multilevel voltage synthesis with high smoothness and reliability.
Solution Approach 2:
The patent implements feedback mechanisms where controllers continuously monitor the output voltage levels and adjust the switching states of their respective modules accordingly. This closed-loop control ensures accurate voltage synthesis and maintains high output smoothness while managing controller complexity through adaptive regulation.
3Reliability
If more components are added to achieve increased output voltage levels, then the voltage quality is improved, but the loss of energy increases due to more switches and components
Solution Approach 1:
The patent optimizes the switching characteristics of individual modules and coupling inductors to minimize local energy losses. By carefully selecting component parameters and optimizing switching patterns for each module, the overall energy efficiency is improved while maintaining high output voltage quality with reduced harmonic distortion.
Solution Approach 2:
The inverter employs periodic switching patterns and pulse width modulation techniques to control the timing and duration of switch operations. This periodic control minimizes switching losses by optimizing the on/off cycles of components, reducing energy dissipation while maintaining the desired multilevel voltage output quality.
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 a smoother AC output voltage with reduced harmonic distortion, balanced current flow, and enhanced safety features, improving the efficiency and reliability of power conversion while managing complexity and component count effectively.
Implementation Method 1
A first inductor L4 and a second inductor L5 may be mutually coupled together. The mutually coupled inductors L4, L5, and L6 may be utilized to smooth a sine-wave of an AC output of the multi-level inverter.
Data Source
AI summary
A multi-level inverter topology is disclosed. A power converter circuit converts a DC source at its input to provide an alternating current (AC) at its output. The power converter circuit may have a controller operably attached to multiple series connections of switches. The controller may control one or more of the multiple series connections of switches to convert a DC input to provide multi-level AC voltages with DC offset across two terminals of the power converter circuit. The multi-level AC voltages with DC offset may then be converted by use of a plurality of series connections of switches to provide a single-phase AC voltage at a first output terminal with respect to at least one of a neutral potential, an earth potential, or a terminal of the power converter circuit.