Battery Management Device Voltage Detection RC Filter
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Solution Overview
Problem
Existing battery management devices face challenges in immediately measuring cell voltage after diagnosis due to the time constant of RC filters, which hinders prompt detection of battery health and safety.
Innovation Solution
A battery management device with a voltage detection unit, filter circuit using a resistor and capacitor, and current source that repeatedly energizes the voltage detection line to change the capacitor's charge, allowing for immediate voltage measurement by diagnosing the resistor's state based on terminal voltage fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an RC filter is connected to the voltage detection line to remove noise, then noise filtering is improved, but measurement timing is delayed due to the time constant of the RC filter
Solution Approach 1:
The current source performs preliminary action by charging the capacitor in the RC filter before voltage measurement. This preliminary charging action prepares the filter in advance so that when measurement is needed, the capacitor is already charged and no standby time is required, thus resolving the contradiction between noise filtering and measurement timing
Solution Approach 2:
The current source performs periodic energization to charge the capacitor at specific intervals. This periodic action synchronizes with the measurement timing requirements, ensuring the capacitor is charged exactly when needed for measurement, eliminating the delay caused by RC filter time constant
2Difficulty of detecting and measuring
If pseudo voltage information is input to diagnose the battery management device, then diagnostic capability is improved, but voltage measurement is delayed due to RC filter time constant
Solution Approach 1:
The system performs preliminary diagnosis using pseudo voltage information and simultaneously charges the RC filter capacitor in advance. This dual preliminary action ensures that both diagnostic data is collected and the filter is prepared for immediate voltage measurement, eliminating the need to wait for the RC filter to settle after diagnosis
Solution Approach 2:
The current source continues to charge the capacitor during and after the diagnosis process, maintaining continuous useful action. This ensures that the capacitor remains charged and ready for immediate voltage measurement, preventing any interruption or delay in the measurement 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
Enables immediate measurement of cell voltage post-diagnosis, effectively detecting abnormal resistor states and ensuring timely battery management, enhancing safety and efficiency in hybrid electric vehicles.
Implementation Method 1
a filter circuit that is configured using a resistor and a capacitor and electrically connected to the voltage detection line
Implementation Method 2
a current source that repeatedly performs an energization operation to cause a current to flow to the voltage detection line in order to change a stored charge amount of the capacitor
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3
AI summary
Measurement of a cell voltage is executed immediately after diagnosis of a battery management device is ended. In a battery management device 10, current sources G11 and G12 repeatedly perform an energization operation to cause a current to flow to voltage detection lines L1, L2 and L3 with a magnitude of the current that enables each amount of charge stored in capacitors C11, C12, and C13 changed by one energization operation to fall within a range corresponding to a fluctuation width of terminal voltages of battery cells 21 and 22 during the energization operation when resistors R11, R12, and R13 are in a normal state. When the difference between the current terminal voltage of the battery cell 21 or 22 and the past terminal voltage of the battery cell 21 or 22 is larger than the predetermined threshold value, the microcomputer 130 diagnoses that the resistor R11, R12 or R13 is in the open state.