Series AC-to-AC Traction Converter for Lower-Voltage Power Devices
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Solution Overview
Problem
Existing electric traction systems face limitations in weight reduction, miniaturization, cost, and efficiency due to the use of high-voltage Si-based IGBTs, with SiC-based devices being costly and unreliable, and the circuit topology being inflexible and difficult to optimize.
Innovation Solution
An electric traction system with a step-down transformer and a traction converter module that connects AC-to-AC power converters in series, allowing the use of power semiconductor devices with reduced voltage ratings, and includes a multi-phase electric motor for improved reliability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If high-voltage Si-based IGBTs are used in traction converters, then the system can handle high voltage requirements, but the weight, volume, and cost increase significantly
Solution Approach 1:
The patent divides the single high-voltage traction converter into multiple low-voltage converter modules connected in series. Each module operates at a lower voltage level, allowing the use of smaller, lighter power semiconductor devices while collectively handling the required high voltage through series connection of multiple modules.
Solution Approach 2:
The patent changes the voltage parameter from a single high-voltage level to multiple lower-voltage levels distributed across series-connected modules. This parameter transformation enables the use of lower-voltage-rated semiconductor devices that are smaller, lighter, and less expensive while maintaining the overall high-voltage capability of the system.
2Stress or pressure
If high-voltage Si-based IGBTs are used, then the system meets voltage requirements, but efficiency and miniaturization are limited
Solution Approach 1:
The system segments the power conversion function into multiple independent low-voltage modules, each capable of operating efficiently at its optimized voltage level. This segmentation allows each module to be designed for optimal efficiency without the compromises required by high-voltage device physics.
3Loss of energy
If SiC-based devices are used to reduce losses and improve efficiency, then energy efficiency improves, but cost and reliability become problematic
Solution Approach 1:
The patent uses conventional, cost-effective silicon-based power semiconductor devices in each module rather than expensive SiC devices. While individual devices have shorter life expectations, the modular architecture allows for easy replacement of failed modules, and the lower cost of standard silicon devices provides significant economic advantage.
4Device complexity
If a single traction converter is used, then the circuit topology is simple, but flexibility and fault tolerance are reduced
Solution Approach 1:
The patent segments the single converter into multiple identical or dissimilar modules that can be independently controlled, configured, and optimized for different functions. This segmentation provides flexibility in circuit topology design, fault isolation, and system reconfiguration while maintaining manageable complexity through modular standardization.
Solution Approach 2:
The modular architecture enables dynamic reconfiguration of the system - modules can be dynamically added, removed, or reconfigured based on operational requirements. The system can adapt its topology and operational characteristics in real-time, providing versatility while maintaining simple individual module designs.
5Weight of moving object
If lower-voltage semiconductor devices are used in series configuration, then weight and cost are reduced, but the system must maintain high-voltage capability
Solution Approach 1:
The patent segments the high-voltage function into multiple low-voltage modules connected in series. Each segment handles a portion of the total voltage, allowing the use of lighter, smaller low-voltage devices while the series connection of segments reconstructs the required high-voltage capability at the system level.
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 system achieves higher efficiency, reduced weight and volume, lower costs, and increased reliability by using lower-voltage semiconductor devices and a flexible circuit topology, enabling phase redundancy and fault tolerance.
Implementation Method 1
a step-down transformer comprising a primary winding for operatively coupling to an AC power supply and a secondary winding which is inductively coupled to the primary winding
Data Source
AI summary
There is provided an electric traction system, comprising: a step-down transformer comprising a primary winding for operatively coupling to an AC power supply and a secondary winding which is inductively coupled to the primary winding; a traction converter module comprising a first input terminal and a second input terminal which are operatively coupled to the secondary winding, and a plurality of AC-to-AC power converters, each of which comprises first and second input nodes, configured to receive AC power and output nodes configured to supply AC power, wherein the first and second input nodes, of the plurality of AC-to-AC power converters are electrically connected in series between the first input terminal and the second input terminal; and at least one electric motor configured to be driven by the traction converter module.