Train Traction Chopper Reuse for Low-Voltage Battery Propulsion
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Solution Overview
Problem
Existing traction systems for electrical trains face challenges in providing sufficient electrical energy for propulsion without relying on external power sources, particularly when external energy is unavailable, and existing solutions often require additional components that increase cost, weight, and complexity.
Innovation Solution
A reconfigured chopper circuitry that functions as both a brake chopper and a step-up chopper, allowing an auxiliary battery with low voltage to power the train's traction motors by adapting its voltage to the required DC link level, utilizing existing components with minimal additions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an auxiliary battery with low voltage is used to power the train without external power sources, then the train can move independently without overhead line power supply, but the battery voltage is too low to magnetize and provide sufficient tractive effort to the traction motors
Solution Approach 1:
The patent combines the brake chopper circuitry with step-up chopper functionality, merging two separate functions into one integrated system. This allows the auxiliary battery to be stepped up to the required DC link voltage level, enabling independent train operation while maintaining sufficient power for traction motors during shunting and emergency operations
Solution Approach 2:
The patent changes the voltage parameter of the auxiliary battery from low voltage (e.g., 110V) to high voltage (DC link level) through the step-up chopper circuitry. This parameter transformation enables the battery to provide adequate tractive effort while maintaining independent operation capability
2Reliability
If separate chopper circuitries are used for brake chopper and step-up chopper functions, then each function can be optimized independently, but the number of components increases leading to higher cost, weight, and complexity
Solution Approach 1:
The patent implements a universal chopper circuitry that performs both brake chopper and step-up chopper functions. The same circuit components are used for both functions depending on operational mode, reducing the number of components while maintaining optimized performance for both braking and voltage conversion operations
Solution Approach 2:
The patent merges the brake chopper and step-up chopper circuitries into a single integrated system, eliminating redundant components and reducing overall system complexity, cost, and weight while maintaining independent optimization of both functions through control unit management
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
Enables cost-effective and efficient train movement over short distances using an auxiliary battery, reducing the number of components and maintaining operational flexibility without external power sources.
Implementation Method 1
a step-up chopper to adapt the voltage level of the auxiliary battery to the voltage level of the DC link
Implementation Method 2
a brake resistor unit whose power level is regulated by a DC/DC converter, also known as braking chopper), designed for dissipating braking energy in the form of heat
Implementation Method 3
a DC/DC converter, also known as braking chopper), designed for dissipating braking energy
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A traction system (2) for a vehicle, e.g. a train or a locomotive, comprising at least one AC traction motor (4) to propel said vehicle; a DC link (6) configured to supply voltage having a predetermined first voltage level to said at least one AC traction motor (4); a first power supply (8) configured to supply said DC link (6), e.g. from overhead contact lines, with voltage at said predetermined first voltage level. In addition, the traction system (2) comprises a second power supply (10) comprising at least one battery providing a predetermined second voltage level, being lower than the predetermined first voltage level; a chopper circuitry (12) connected to the DC link (6); a brake resistor unit (14) comprising at least one brake resistor, and a control unit (16). The traction system (2) also comprises a battery-operation propulsion (BOP) unit (18) configured to connect the second power supply (10) to the DC link (6), The control unit (16) is configured to control the BOP unit (18) to either: a) function as a step-up chopper to adapt the predetermined second voltage level to the predetermined first voltage level such that the DC link (6) is supplied by the second power supply (10), or b) function as a brake chopper for dynamic/rheostatic braking.