HV Battery Arrangement with Series-Parallel Switching for Fast Charging
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Solution Overview
Problem
High voltage (HV) battery arrangements in motor vehicles face challenges in achieving high failure safety and efficient operation, particularly during charging, due to the need for prolonged network availability during failures and the risk of voltage fluctuations and damage from short circuits, which contradicts the safety strategy of lithium ion batteries.
Innovation Solution
An HV battery arrangement with two battery units connected to separate onboard network parts and a switching device that allows them to be connected in series or disconnected, enabling independent operation of each unit during failures and optimizing charging modes by connecting them in parallel or series depending on the external power source voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the HV battery units are connected in parallel for charging, then charging speed is improved, but the complexity of switching device control increases
Solution Approach 1:
The system dynamically reconfigures the battery units between series and parallel connections based on operational mode (charging vs. discharging). The switching device changes the electrical topology from series during charging to parallel during discharging, allowing optimization for each operational state without permanent complexity
Solution Approach 2:
The switching device performs multiple functions: it connects battery units in series for charging, in parallel for discharging, and can isolate individual units during failures. This multi-functionality reduces the need for separate dedicated circuits for each operation mode
2Reliability
If the HV battery units are electrically disconnected during failures, then safety is improved, but the ability to maintain network availability deteriorates
Solution Approach 1:
The HV battery system is segmented into independent battery units with separate connections to the onboard network. The switching device can isolate individual failed units while maintaining electrical connections to other healthy units, allowing the network to remain operational with reduced capacity rather than complete failure
Solution Approach 2:
The switching device acts as an intermediary between the battery units and the onboard network. It intelligently controls the electrical connections, maintaining network availability by routing power through healthy units while isolating failed ones, thus mediating between safety requirements and operational continuity
3Productivity
If the HV battery units are connected in series for high-voltage charging, then charging efficiency is improved, but the risk of voltage fluctuations and short circuit damage increases
Solution Approach 1:
The switching device is designed to detect failure conditions and activate protective isolation before voltage fluctuations or short circuits can cause damage. By monitoring battery unit status and preemptively isolating problematic units, the system cushions against harmful effects before they propagate through the series connection
Solution Approach 2:
The system applies preliminary anti-action by establishing protective disconnections in anticipation of potential failures during series charging. The switching device can pre-isolate battery units that show signs of distress, preventing the escalation of voltage fluctuations or short circuits that would otherwise damage the charging system
Data Source
AI summary
An HV battery arrangement with a first HV battery unit that can be electrically coupled to a first HV onboard network part having a first drive unit of the motor vehicle, and with a second HV battery unit that can be electrically coupled to a second HV onboard network part having a second drive unit of the motor vehicle, wherein, between the first HV battery unit and the second HV battery unit, a switching device is arranged, by which the first and the second HV battery units can be connected in series and can be electrically disconnected from each other. The HV battery arrangement further has a control unit for actuating at least the switching device.