Battery Module Ohmic Resistance Measurement via Load Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining the ohmic internal resistance of battery modules, such as those in electric or hybrid vehicles, are typically conducted outside normal operation and lack the timeliness and precision needed for continuous monitoring of battery wear and durability.
Innovation Solution
A method that involves connecting a battery module under load to another module, measuring voltage levels before and after the connection, and using these measurements to determine impedance, allowing for simultaneous and timely assessment of battery state and wear, integrated into a battery management system for continuous monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage measurements are taken before and after current pulses lasting one or more seconds, then the ohmic internal resistance can be determined according to ISO 12405, but the measurement timing is delayed and lacks simultaneity, reducing the timeliness of battery wear detection
Solution Approach 1:
The patent utilizes the periodic switching operation of battery modules in multi-phase battery systems, where modules are periodically connected and disconnected to generate alternating voltages. This periodic action creates natural current pulses that flow through the battery modules during normal operation, enabling impedance measurements to be taken at these periodic intervals rather than requiring separate dedicated measurement periods. The voltage levels are measured before and after each periodic connection event, transforming the measurement process into a periodic operation that occurs during normal battery system operation.
Solution Approach 2:
The patent enables continuous monitoring of battery module impedance by performing measurements during the normal operational cycles of the battery system. Instead of stopping operation for dedicated measurements, the useful action of current flow continues uninterrupted while voltage measurements are taken at appropriate moments within the operational cycle. This continuity allows the battery management system to continuously track impedance changes and detect wear without interrupting the battery's useful function of powering the vehicle.
2Reliability
If impedance measurements are performed outside normal battery operation, then measurement interference is minimized, but continuous monitoring of battery wear and durability during operation cannot be achieved
Solution Approach 1:
The patent makes the battery management system perform multiple functions: it simultaneously manages normal battery operation (charging/discharging control) and performs impedance measurements for wear detection. The same control system that manages the periodic switching of battery modules also captures voltage measurements for impedance calculation. This multi-functionality eliminates the need for separate dedicated measurement systems and enables continuous monitoring integrated into the normal operational framework.
Solution Approach 2:
The battery system performs self-diagnosis by using its own operational current pulses to generate the measurement conditions needed for impedance determination. The normal switching operations that are necessary for the battery's function also create the current variations needed for wear detection. The system essentially monitors itself during its own operation, without requiring external testing equipment or separate measurement procedures.
3Loss of time
If voltage levels are measured before and after connecting a battery module under load to another module, then simultaneous and timely assessment of battery state is enabled, but the system complexity increases due to required module connections
Solution Approach 1:
The patent leverages the dynamic switching capability of battery modules in multi-phase systems, where modules can be dynamically connected and disconnected during operation. This dynamic reconfiguration is already necessary for generating alternating voltages and balancing cell states. The measurement process utilizes these existing dynamic transitions rather than requiring static, fixed configurations. The system adapts its measurement timing to the dynamic operational state, measuring voltage levels before and after each connection event as it naturally occurs in the dynamic operation.
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 accurate and continuous monitoring of battery module state and wear during operation, detecting excessive wear and aging, thereby improving maintenance and efficiency of multi-phase battery systems in vehicles.
Implementation Method 1
The invention relates to a method for determining an ohmic internal resistance of a battery module with at least one battery cell... determining the ohmic internal resistance from measurements of voltage levels
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a method for determining the internal ohmic resistance of a battery module (100) comprising at least one battery cell, for example a lithium-ion battery cell of the type used in traction batteries (140) of electric or hybrid motor vehicles, that is, in motor vehicles comprising drives (150) that are at least partly or intermittently electrically driven. The invention also relates to a motor vehicle and a battery management system (160). The disclosed method comprises the determination of the internal ohmic resistance from measurements of voltage intensities. The invention is characterised in that the method comprises the connection of the battery module (100) to at least one other battery module (100) that is subject to a load current, and comprises the measurement of voltage intensities in the battery module (100) before and after said connection. This allows a measurement of current and voltage intensities to take place significantly closer to real time and thus almost simultaneously, which in turn allows the determination of the actual wear condition of the battery module (100) to be improved and the durability of individual battery cells or of battery modules (100) to be predicted.