Multi-Level Current Inverter for Renewable Energy Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional DC/AC inverters for renewable energy systems face high switching losses and inefficiencies due to the need for high-frequency semiconductors and bulky transformers, which increase costs and reduce power density.
Innovation Solution
A multi-level-current concept is implemented using three routes for current formation: positive, negative, and intermediate currents, with high-frequency semiconductors shaping the waveform and low-frequency semiconductors distributing it, allowing for a sinusoidal three-phase output with reduced semiconductor ratings and eliminating the need for transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional two-level voltage source inverter topology is used, then component count is reduced, but switching losses increase due to high-frequency semiconductors handling full DC link voltage
Solution Approach 1:
The inverter is segmented into multiple levels (three-level topology) where the voltage is divided into smaller steps. The output voltage is formed by combining different voltage levels from multiple semiconductor switches, reducing the voltage stress on each individual switch and enabling lower switching losses
Solution Approach 2:
The patent changes the voltage parameter distribution across semiconductor switches by using multi-level topology. Instead of one switch handling the full DC link voltage, multiple switches share the voltage in smaller increments, allowing the use of semiconductors with lower breakdown voltage ratings and reduced switching losses
2Loss of energy
If multi-level voltage source inverter topology is used, then switching losses are reduced, but device complexity increases with more switches and clamping components
Solution Approach 1:
The semiconductor switches in the multi-level inverter perform multiple functions: they contribute to voltage level generation, provide clamping action, and enable current distribution. This multi-functionality reduces the need for separate dedicated clamping components, simplifying the overall device structure despite the multi-level topology
Solution Approach 2:
The patent merges the clamping function with the voltage generation function by using the same semiconductor switches for both purposes. The clamping action is integrated into the switching operation itself, eliminating the need for separate clamping circuits and reducing overall device complexity
3Volume of stationary object
If high switching frequency is used to reduce inductor size, then inductor losses are reduced, but semiconductor switching losses increase
Solution Approach 1:
The patent changes the voltage parameter across semiconductors by using multi-level topology, reducing the voltage stress on each switch. This enables the use of lower-frequency switching devices that can operate at moderate switching frequencies without excessive switching losses, while still achieving reduced inductor sizes through the multi-level voltage structure
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
This approach reduces switching losses, lowers costs, and increases power density by using fewer high-current, high-frequency devices and smaller output inductors, while ensuring a sinusoidal and in-phase three-phase output current.
Implementation Method 1
Each route may comprise high-frequency semiconductors for shaping the current waveform
Implementation Method 2
Each route may comprise high-frequency semiconductors for shaping the current waveform
Implementation Method 3
Each route may comprise high-frequency semiconductors for shaping the current waveform
Implementation Method 4
low-frequency semiconductors distributing it, allowing for a sinusoidal three-phase output
Data Source
AI summary
The present disclosure discloses a method and an apparatus for implementing the method for producing a three-phase current to a three-phase output. The method comprises producing a positive current, a negative current, and an intermediate current by using switching converters. The produced positive current follows a path of a highest phase of a sinusoidal three-phase signal at a given time, the produced negative current follows a path of a lowest phase of the three-phase signal at the given time, and the produced intermediate current follows a path of a phase of the three-phase signal between the highest and the lowest phase at the given time. The produced currents are switched to each phase conductor of the three-phase output in sequence so that phase currents of the three-phase current are formed in the output conductors.