BEV Energy Storage Reconfiguration with Auxiliary Battery Preconditioning
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Solution Overview
Problem
Battery electric vehicles (BEVs) face challenges in efficiently reconfiguring their energy storage systems during transitions between propulsion and recharging, particularly in ensuring that low voltage DC auxiliary batteries can service electrical loads during reconfiguration without compromising the high voltage DC battery modules' performance.
Innovation Solution
A method involving preconditioning the low voltage DC auxiliary battery by establishing predetermined parameters such as temperature and state of charge, isolating it from high voltage DC battery modules, and selectively configuring the energy storage system to alternate between series and parallel arrangements of HV DC battery modules, with a controller managing the transition and current flow to maintain discharge readiness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the LV DC auxiliary battery remains connected to HV DC battery modules during reconfiguration, then the auxiliary battery can service electrical loads continuously, but the auxiliary battery may be damaged by voltage spikes or improper voltage conditions during reconfiguration
Solution Approach 1:
The system performs preliminary actions by preconditioning the auxiliary battery (establishing temperature and state of charge parameters) before reconfiguration begins, and by pre-establishing isolation switches that can quickly disconnect the auxiliary battery from HV modules before voltage conditions become hazardous during reconfiguration
Solution Approach 2:
Isolation switches serve as intermediaries between the auxiliary battery and HV battery modules, allowing the system to control electrical connection status. These switches enable the auxiliary battery to be disconnected from HV modules during reconfiguration while maintaining its ability to service LV loads, thus protecting the auxiliary battery without completely interrupting its load-servicing function
2Productivity
If the energy storage system reconfigures quickly between series and parallel arrangements, then recharging efficiency is improved, but the auxiliary battery may not have sufficient time to precondition and service loads properly
Solution Approach 1:
The system performs preliminary preconditioning of the auxiliary battery (controlling temperature and state of charge) before reconfiguration events, ensuring the battery is ready to service loads immediately when needed. This advance preparation eliminates delays during actual reconfiguration operations
Solution Approach 2:
The system dynamically adapts the timing and duration of auxiliary battery isolation based on detected reconfiguration conditions. The control system monitors system state and adjusts the isolation duration to match the actual reconfiguration timeline, allowing faster reconfigurations when conditions permit while ensuring adequate protection when needed
3Reliability
If the auxiliary battery is isolated from all HV DC battery modules during reconfiguration, then the auxiliary battery is protected from voltage conditions, but the auxiliary battery cannot be recharged or have its state optimized during the same period
Solution Approach 1:
The system implements periodic reconfiguration cycles where the auxiliary battery is alternately connected and isolated from HV modules. During isolated periods, the auxiliary battery protects itself while servicing loads; during connected periods, it can be recharged or have its state optimized. This periodic alternation ensures both protection and energy management over time
Solution Approach 2:
The system temporarily discards the opportunity to charge or optimize the auxiliary battery during reconfiguration events by isolating it from HV modules. However, this temporary sacrifice is recovered in subsequent periods when the auxiliary battery is reconnected and can accept charge or state optimization, ensuring long-term energy management
Data Source
AI summary
A battery electric vehicle includes a high voltage rechargeable energy storage system (RESS). The RESS includes several battery modules reconfigurable among parallel and series arrangements. During reconfiguration transitions, a low voltage battery services low voltage loads of the battery electric vehicle. The low voltage battery is preconditioned in advance of reconfigurations.