Traction Energy Storage Parallel Switching Voltage Equalization
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Solution Overview
Problem
Modular energy storage systems in vehicles face limitations in switching energy storage units in parallel due to voltage differences, leading to restricted vehicle service and frequent wear on switching contacts, which can result in short switching periods and reduced system efficiency.
Innovation Solution
A procedure for determining the internal resistance and idle voltage of energy storage units, controlling current to minimize voltage differences, and switching units when the voltage deviation is within a predetermined threshold, thereby reducing wear on switching contacts and increasing switching frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If energy storage units are switched in parallel without voltage equalization, then switching frequency increases, but switching contact wear increases and system reliability decreases
Solution Approach 1:
The patent applies preliminary action by equalizing the idle voltages of energy storage units before switching them in parallel. The control unit actively adjusts the voltage of units with lower idle voltage to match units with higher idle voltage, ensuring that when switching occurs, the voltage difference is minimal. This prevents large compensation currents and reduces switching contact wear, thereby extending component lifespan while maintaining high switching frequency.
2Adaptability or versatility
If energy storage units with different idle voltages are connected in parallel, then system scalability improves, but compensation current increases causing switching shooter damage
Solution Approach 1:
The patent converts the harmful effect of voltage differences into a beneficial control mechanism. Instead of allowing random voltage differences to cause harmful compensation currents, the control unit actively measures and equalizes idle voltages before parallel connection. This transforms the potential harm into a controlled process where voltage equalization is deliberately performed to enable safe parallel switching, thus maintaining system scalability without generating damaging compensation currents.
3Manufacturing precision
If voltage equalization is performed by charging or discharging energy storage units, then idle voltage matching improves, but energy loss increases and service time is restricted
Solution Approach 1:
The patent introduces an intermediary approach by using the control unit to actively manage and equalize voltages through controlled current flow, rather than allowing direct uncontrolled equalization. The control unit acts as an intermediary that regulates the equalization process, enabling precise voltage matching while minimizing energy loss by performing equalization only when necessary and using optimized current control during the process.
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 allows for more frequent and timely switching of energy storage units, reducing wear on switching contacts and enabling longer switching periods without disrupting vehicle operation, such as during driving or charging, by controlling current to maintain voltage differences within safe limits.
Implementation Method 1
A voltage drop caused by a controlled current I and the inner resistance R deviates the system voltage Usys from the idle voltage Uocv of the at least one further energy store TES to be switched on
Data Source
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AI summary
A technique for operating a traction energy storage system (100) of a vehicle with several parallel-connectable energy storage devices (102) is described. With regard to a procedural aspect of the technique, a subset (112) of the energy storage devices is initially connected in parallel. At least one additional energy storage device is not connected in parallel with the subset already connected in parallel. The internal resistance (116) of the parallel-connected subset (112) of the energy storage devices, the open-circuit voltage (114) of the parallel-connected subset (112) of the energy storage devices, and the open-circuit voltage of the at least one additional energy storage device are determined.A current (128) through the parallel-connected subset (112) of the energy storage devices is controlled such that the open-circuit voltage (114) of the parallel-connected subset (112) of the energy storage devices and a voltage drop caused by the current (128) and the internal resistance (116) result in a voltage (124) of the parallel-connected subset (112) of the energy storage devices that deviates from the open-circuit voltage (302) of the at least one additional energy storage device by less than a predetermined switching voltage. Meanwhile, the at least one additional energy storage device is connected in parallel with the parallel-connected subset (112) of the energy storage devices.