Railway Traction Power Supply With Boost Converter Overvoltage Absorption
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Solution Overview
Problem
Existing power supply systems for railway vehicles face challenges in managing overvoltage from DC catenaries, which can damage the system and require additional protection components, increasing size and weight.
Innovation Solution
The proposed power supply system incorporates a DC-DC converter configured as a boost converter to absorb overvoltage from the DC catenary, eliminating the need for specific protection components and allowing for a smaller and lighter system. Additionally, the system includes a traction battery connected directly to the DC bus for efficient energy management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If specific protection components are added to protect against overvoltage, then system reliability is improved, but device complexity and weight increase
Solution Approach 1:
The DC-DC converter is designed to perform multiple functions: it not only converts DC voltage from the catenary to the required level for the traction inverter, but also inherently protects the system from overvoltage conditions. By configuring the converter with adequate voltage headroom and appropriate control logic, it can absorb voltage peaks without requiring separate protection circuitry, thus eliminating the need for additional protection components while maintaining system reliability
Solution Approach 2:
The protective function against overvoltage is extracted from being a separate component and integrated into the DC-DC converter's operational characteristics. The converter's design allows it to naturally handle voltage variations and peaks through its conversion ratio and control mechanism, removing the need for dedicated protection devices and simplifying the overall system architecture
2Reliability
If protection components are added to handle overvoltage, then system reliability is improved, but system weight increases
Solution Approach 1:
The DC-DC converter serves dual purposes: voltage conversion and overvoltage protection. By designing the converter with sufficient voltage handling capability and appropriate control strategies, it can absorb and manage voltage peaks without requiring additional protection components, thereby avoiding the extra weight that would result from adding separate protection devices
Solution Approach 2:
The DC-DC converter is designed to protect itself and the downstream equipment from overvoltage conditions through its inherent operational characteristics. By configuring the converter to operate with adequate voltage headroom and using control logic that manages voltage peaks, the system achieves self-protection without external intervention or additional components, reducing overall system weight
3Device complexity
If DC voltage from catenary is used directly, then device complexity is reduced, but system reliability deteriorates due to overvoltage damage
Solution Approach 1:
The DC-DC converter is designed to perform multiple functions in a single stage: it converts the catenary voltage to the required level for the traction inverter while simultaneously providing overvoltage protection. This multi-functional approach maintains relatively simple system architecture while ensuring reliability, as the converter's design allows it to handle voltage variations and peaks without requiring additional protection circuitry
4Adaptability or versatility
If AC catenary and AC-DC converter are used, then adaptability to different catenary types is improved, but device complexity increases
Solution Approach 1:
Instead of designing the power supply system to adapt to different catenary types through complex converter configurations, the invention inverts the approach by designing the system specifically for DC catenaries. This simplifies the converter configuration and reduces device complexity, while still achieving adaptability through the DC-DC converter's ability to handle a wide range of DC voltage inputs and the traction battery's role in managing power flow
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 effectively manages overvoltage without additional protection components, resulting in a smaller, lighter, and more efficient power supply system. The direct connection of the traction battery to the DC bus enhances energy efficiency and reduces the size of the DC-DC converter, further contributing to the system's compactness and performance.
Implementation Method 1
a DC-DC converter connected between the connection point and the DC bus, which is configured to boost the DC voltage from the catenary to a value higher than the value of the DC voltage provided by the catenary
Implementation Method 2
a traction inverter connected to the DC bus and configured to convert DC electrical power from the DC bus to AC three-phase power to electrically supply at least one traction motor
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a power supply system for a railway vehicle, comprising a connection point (2) for being connected to a catenary; a DC bus (4); a traction inverter (5) connected to said DC bus (4), for converting a DC electrical power from said DC bus (4) into AC power to supply a traction motor of the railway vehicle; and a battery (6) connected to said DC bus (4). The connection point (2) is configured to connect the power supply system (1) to a DC catenary that provides a DC voltage to the power supply system (1) and said power supply system (1) comprises a boost DC-DC converter (3) connected to the connection point (2) and configured to boost said DC voltage from the catenary.