Battery Management Clock Plausibility Using Measurement Cycles
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Solution Overview
Problem
Current systems for diagnosing the state of health and charge of lithium ion batteries in high voltage and low voltage systems face inaccuracies due to the reliance on an external vehicle clock, leading to pseudo-errors, especially during time changes or hardware errors, which can incorrectly declare batteries defective.
Innovation Solution
A system that includes a microcontroller with a second clock and a cell measurement chip with a third clock, allowing the system to calculate elapsed time during the battery's off state and plausibilize the first clock's accuracy, eliminating the need for an external clock and ensuring OBD2 compliance by periodically taking measurements and comparing them to predetermined frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external vehicle clock is used for diagnosis during battery off state, then the system can provide time reference for SOH determination and equalization processes, but the clock accuracy is insufficient leading to pseudo-errors and incorrect defect declarations
Solution Approach 1:
The patent creates a virtual clock by counting measurement cycles performed by the cell measurement chip during battery off state. Instead of relying on an external vehicle clock, the system generates its own time reference by measuring how many periodic measurement cycles occur between on-state transitions, thereby copying the time-measurement function without the accuracy problems of external clocks
Solution Approach 2:
The measurement cycle counter acts as an intermediary between the cell measurement chip's periodic measurements and the diagnosis functions. This intermediary component translates a series of periodic measurement events into a time duration value that can be used for SOH determination and equalization processes, providing accurate timing without requiring an external clock
2Reliability
If the system clock is switched on during battery off state for diagnosis, then time measurement is possible, but power consumption increases and other clocks must be disabled
Solution Approach 1:
The cell measurement chip continues its periodic measurement function during battery off state without requiring additional power for a separate clock system. The existing measurement cycles serve dual purposes: maintaining battery cell monitoring functionality and providing the time reference needed for diagnosis, thereby making the measurement system self-sufficient for both tasks
Solution Approach 2:
The measurement cycles of the cell measurement chip perform multiple functions simultaneously: they continue to monitor battery cell states (original function) and also serve as the basis for time measurement during off state (new function). This multi-functionality eliminates the need for separate clock systems and reduces overall power consumption
3Device complexity
If external clocks are used for time reference, then the system structure is simplified, but pseudo-errors occur due to time changes and hardware errors
Solution Approach 1:
The patent extracts the time-reference function from the external vehicle clock system and implements it independently within the battery management system using the measurement cycle counter. This extraction eliminates the dependency on external clock hardware and its associated errors while maintaining the necessary time measurement capability for accurate diagnosis
Data Source
AI summary
A system for plausibilizing a first clock of a system base chip of an electrochemical energy store that is turned on during an off state of the electrochemical energy store.