Rail Vehicle Energy Controller for High-Voltage System Downsizing
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Solution Overview
Problem
Dual-mode rail vehicles face increased weight and complexity due to the addition of traction batteries on electrified routes, necessitating a solution to reduce the size of the high-voltage system while utilizing on-board energy storage effectively.
Innovation Solution
A method and controller for controlling the on-board energy storage system of rail vehicles, which determines recoverable kinetic energy during braking and compares it with stored energy to adjust the high-voltage AC line current supply, ensuring only the necessary energy is drawn from the line supply to maintain a target energy level in the traction battery, thereby reducing peak and RMS current requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a traction battery is added to an electrified rail vehicle, then on-board energy storage capability is improved, but vehicle weight and system complexity increase significantly
Solution Approach 1:
The system performs preliminary calculation of recoverable kinetic energy during braking events before the vehicle actually needs that energy. By pre-calculating energy availability based on mass and velocity, the system can proactively manage battery charging during regenerative braking, optimizing energy capture without adding excessive weight or complexity to the vehicle platform.
Solution Approach 2:
The control system continuously monitors the state of charge (SOC) of the traction battery and uses this feedback to dynamically adjust energy management strategies. By comparing actual SOC against target SOC levels, the system optimizes the balance between using on-board storage and drawing from the high-voltage line supply, thereby reducing the required battery capacity and overall system weight.
2Use of energy by moving object
If a traction battery is added to an electrified rail vehicle, then on-board energy storage capability is improved, but system complexity increases
Solution Approach 1:
The high-voltage system is designed to serve multiple functions: it acts as both the primary power source during traction and as a charging source for the traction battery during regenerative braking. This multi-functionality reduces the need for separate dedicated systems, thereby limiting the increase in system complexity while maintaining effective on-board energy storage capability.
Solution Approach 2:
The control system acts as an intermediary that manages the interaction between the high-voltage line supply and the traction battery. By introducing this control layer that handles SOC monitoring and energy flow management, the system simplifies the overall architecture compared to having multiple independent control systems, reducing complexity while achieving effective energy management.
3Weight of moving object
If the high-voltage system size is reduced, then vehicle weight and cost decrease, but the ability to supply peak current is compromised
Solution Approach 1:
The system pre-charges the traction battery during periods of low power demand, such as during regenerative braking events, so that energy is stored in advance. This preliminary energy storage allows the reduced high-voltage system to rely on the battery for peak power demands, thereby maintaining peak current supply capability without requiring oversized high-voltage equipment.
Solution Approach 2:
The control system continuously manages energy transfer between the high-voltage line supply and the traction battery to maintain optimal state of charge. This continuous energy management ensures that the battery is always ready to supplement the reduced high-voltage system during peak demand periods, maintaining adequate power supply capability throughout operation without requiring excessive high-voltage system capacity.
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 approach significantly reduces the size and weight of the high-voltage equipment by optimizing energy usage from the on-board storage system, minimizing the components needed in the high-voltage system and lowering operational costs.
Implementation Method 1
The present value of the recoverable kinetic energy may be calculated by the energy controller using the mass and the present velocity of the rail vehicle taking into account the transformation losses
Data Source
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AI summary
The present subject matter relates to a method, a controller, and a computer program product for controlling an on-board energy storage system of a dual-mode rail vehicle. The dual-mode rail vehicle may comprise a high-voltage system, to draw energy from a high-voltage AC line supply, and an on-board energy storage such as a traction battery. The method may comprise the steps of determining a present value of recoverable energy, receiving a present value of energy stored in an on-board energy storage, adding both values to determine a total energy value, comparing the total energy value with a target energy value, determining a required line current depending on the difference between the target energy value and the total energy value, transmitting a minimum value from the determined required line current and a predetermined maximum line current as line current reference value to a high-voltage system controller, and controlling a line current of the rail vehicle according to the line current reference value.