Three-Level Power Converter Current Path Segmentation
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Solution Overview
Problem
Conventional three-level power converting apparatuses experience increased conduction loss and temperature issues due to high current density at the intermediate potential terminal, leading to inefficient heat dissipation and potential instability.
Innovation Solution
The apparatus incorporates MOSFETs and flywheel diodes in series with IGBTs, allowing for multiple current paths during neutral point potential output, reducing conduction loss and heat concentration by dispersing current flow through additional paths and controlling switching element operation to manage temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single current path is used in conventional three-level power converting apparatus, then the circuit structure is simple, but the current density increases and conduction loss increases when intermediate potential terminal voltage is output
Solution Approach 1:
The patent divides the single current path into multiple current paths by adding fifth and sixth switching elements. When the intermediate potential terminal voltage is output, the current is segmented and flows through multiple parallel paths instead of a single path, reducing current density and conduction loss in each individual path while maintaining overall circuit functionality.
2Device complexity
If a single current path is used in conventional three-level power converting apparatus, then the circuit structure is simple, but the temperature of elements increases due to heat concentration
Solution Approach 1:
The patent segments the current flow into multiple paths using additional switching elements, which distributes the heat generation across multiple elements rather than concentrating it in one path. This segmentation of thermal load prevents excessive temperature rise in individual elements.
Solution Approach 2:
The patent employs dynamic control of switching elements to actively manage current distribution and temperature. By dynamically switching between different current paths based on temperature conditions, the system prevents heat concentration and maintains element temperatures within safe operating ranges.
3Loss of energy
If MOSFETs and flywheel diodes are added to create multiple current paths, then conduction loss is reduced, but the device complexity increases
Solution Approach 1:
The patent adds fifth and sixth switching elements (MOSFETs with flywheel diodes) to segment the current into multiple paths. Although this increases the number of components, the segmentation enables significantly reduced conduction loss by distributing current density, achieving a favorable trade-off between complexity and energy efficiency.
Solution Approach 2:
The patent changes the electrical parameters (current density, conduction loss) by introducing additional switching elements. The parameter change in circuit topology (adding paths) results in improved energy efficiency, accepting increased complexity as a necessary trade-off for achieving lower conduction losses.
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 configuration effectively reduces conduction loss and heat accumulation, enhancing efficiency and reliability by distributing current flow and managing temperature fluctuations across switching elements.
Implementation Method 1
The apparatus incorporates MOSFETs and flywheel diodes in series with IGBTs, allowing for multiple current paths during neutral point potential output, reducing conduction loss and heat concentration by dispersing current flow through additional paths
Implementation Method 2
controlling switching element operation to manage temperature
Data Source
Figure 1
Figure 2-1~2-1(2)
Figure 2-2~2-2(4)
AI summary
First to sixth switching elements (1 to 6) forming a power conversion circuit for one phase in a three-level power converting apparatus include transistor elements (1a to 6a) and diode elements (1b to 6b) connected in reverse parallel to the transistor elements (1a to 6a). Second, third, fifth, and sixth transistor elements (2a, 3a, 5a, and 6a) are configured by MOSFETs that enable an electric current to flow in two directions.