Power Conversion System for Railway Vehicles
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Solution Overview
Problem
Electric vehicles, such as railway vehicles, face power supply disruptions when traveling through non-electric sections where overhead wires do not provide power, leading to potential power outages for onboard loads.
Innovation Solution
A power conversion system that includes AC to DC and DC to AC conversion units, a battery device, and a control unit to manage power supply, allowing the system to convert and stabilize power, and utilize battery discharge in emergencies to maintain load power and enable vehicle travel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the vehicle travels through non-electric sections without overhead wire power supply, then the vehicle can maintain mobility, but power supply to onboard loads becomes unstable or interrupted
Solution Approach 1:
The battery device is charged in advance during electric sections before entering non-electric sections. The power conversion device stores energy preliminarily by converting AC power to DC power and charging the battery, so that when overhead wire power is unavailable, the pre-charged battery can immediately take over to maintain stable power supply to loads without interruption.
Solution Approach 2:
The battery device acts as an intermediary energy storage medium between the overhead wire power source and the onboard loads. When direct power supply from overhead wires is interrupted in non-electric sections, the battery serves as a intermediate power source, receiving power from the power conversion device and delivering it to loads, thereby bridging the power supply gap and ensuring continuous operation.
2Reliability
If large capacity capacitors are used to maintain power during outages, then power supply stability improves, but device complexity and cost increase
Solution Approach 1:
The system dynamically switches between different power sources based on real-time conditions. During electric sections, the primary power source is the overhead wire supply. When entering non-electric sections, the system dynamically transitions to using the battery device as the primary power source. This dynamic power source switching allows the use of smaller, more manageable capacitance values compared to a static system that would require large capacitors to handle all contingencies.
Solution Approach 2:
The invention changes the operational parameters of the power conversion device based on the power supply status. When overhead wire power is available, the device operates in normal conversion mode. When power outage occurs, the device changes its operating parameters to draw power from the battery device instead, adjusting its input voltage range and conversion characteristics. This parameter adaptation allows efficient operation with smaller capacitance values across different operating conditions.
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 effectively stabilizes power supply to loads and enables continued vehicle operation by discharging the battery during power outages, reducing the need for high capacitance and minimizing power loss, thus ensuring reliable operation in non-electric sections.
Implementation Method 1
an AC to DC conversion unit for loads (110), which is configured to convert AC power supplied from overhead wires via windings for loads (500, 102) of a main transformer into DC power
Implementation Method 2
a DC to AC conversion unit for AC loads (120), which is configured to perform conversion into AC power for loads for driving an AC load (LAC)
Implementation Method 3
a battery device (200), which is connected to power lines connecting DC power output terminals of the AC to DC conversion unit for loads (110) and DC power input terminals of the DC to AC conversion unit for AC loads (120) and the DC to AC conversion unit for DC loads (160) and which is configured to discharge energy stored in advance when the power supplied from the windings for loads (500, 102) of the main transformer is reduced
Data Source
AI summary
A power conversion system includes a transformer, a power conversion device for travel, a power conversion device for auxiliary power sources, and an electrical storage device. The power conversion device for auxiliary power sources includes a first AC to DC conversion unit, a power conversion unit for AC loads, and a power conversion unit for DC loads. The power conversion unit for AC loads converts DC power into AC power and supplies it to an AC load. The power conversion unit for DC loads converts DC power produced through conversion by the first AC to DC conversion unit into DC power and supplies it to a DC load. The electrical storage device is connected to power lines connecting DC power output terminals of the first AC to DC conversion unit and DC power input terminals of both the power conversion units for AC and DC loads. When power supplied from a tertiary winding of the transformer to the first AC to DC conversion unit is reduced, the electrical storage device discharges power corresponding to the power reduction.