Battery Pack Current Differential Measurement via Magnetic Field Cancellation
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Solution Overview
Problem
Existing battery systems, particularly lithium-ion batteries used in stationary and vehicle applications, face challenges in effectively monitoring and controlling cell currents to prevent overloading and ensure uniform loading of cells, which is crucial for efficient energy management and longevity.
Innovation Solution
A battery pack design that includes a device to measure the difference between two cell currents using magnetic fields generated by wound elements, with a magnetic field sensor and evaluating unit to determine the differential current without direct electrical contacting, minimizing measurement errors and costs, especially in high current and voltage scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct electrical contacting is used to measure cell current difference, then measurement can be obtained, but measurement errors increase and cost/effort for contacting components increases
Solution Approach 1:
The patent introduces magnetic fields as an intermediary to measure cell current differences. Instead of directly contacting electrical components, the invention uses magnetic field sensors to detect the magnetic fields generated by currents in the jelly rolls. The magnetic field serves as a mediator that transfers information about current differences without requiring direct electrical contact, thereby eliminating insulation requirements and reducing measurement errors.
Solution Approach 2:
The patent replaces the mechanical/electrical contact-based measurement system with a magnetic field-based measurement system. By substituting direct electrical contacting with magnetic field sensing, the invention eliminates the need for complex insulation and contacting components, while improving measurement precision through non-contact detection.
2Reliability
If costly insulation is used for high cell currents and voltages, then reliability is improved, but cost and device complexity increase
Solution Approach 1:
The magnetic field acts as an intermediary that allows measurement without direct electrical contact. Since the magnetic field sensor does not need to be electrically isolated from high currents and voltages, costly insulation components are eliminated while maintaining measurement reliability through non-contact detection.
Solution Approach 2:
The invention replaces the insulation-based protective system with a magnetic field-based measurement system. By substituting electrical contact with magnetic field sensing, the need for insulation components is eliminated, reducing both cost and device complexity while maintaining reliability.
3Device complexity
If magnetic field sensing is used to measure cell current difference, then contacting components and insulation are eliminated, but measurement of superimposed fields may be affected by interference
Solution Approach 1:
The patent extracts only the differential information from the magnetic fields by using a magnetic field sensor positioned to detect the difference between the two jelly roll fields. By focusing on the differential measurement rather than measuring each field separately, the system eliminates the need for complex contacting components while minimizing the impact of interference fields through differential detection.
4Object-generated harmful factors
If two jelly rolls are oppositely wound and installed, then electromagnetic radiation is reduced, but device complexity for arrangement increases
Solution Approach 1:
The patent employs asymmetric (opposite) winding directions of the two jelly rolls to generate magnetic fields that counteract each other. This asymmetric arrangement reduces electromagnetic radiation by creating opposing fields that cancel out, while the regularity of the opposite winding pattern keeps the arrangement complexity manageable.
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
This solution allows for precise detection of differential currents with minimal interference, enabling effective balancing of cell loads and state of health assessment, reducing the need for costly insulation and complex contacting methods, while maintaining reliability and efficiency in high-demand applications.
Implementation Method 1
a first battery cell has a first wound element, consisting of a first electrode layer and a second electrode layer, which causes a first magnetic field via a first of the cell currents, and a second battery cell has a second wound element, consisting of a third electrode layer and a fourth electrode layer, which causes a second magnetic field via a second of the cell currents
Implementation Method 2
a magnetic field sensor, which is configured to measure a superimposed field consisting of the first magnetic field and the second magnetic field, and comprises an evaluating unit which is configured to determine a difference between the first and the second cell current from the measured superimposed field
Data Source
AI summary
The invention relates to a battery pack having a plurality of electrochemical battery cells, comprising a device for measuring a difference between two cell currents of two different battery cells, wherein a first battery cell has a first wound element, consisting of a first electrode layer and a second electrode layer, which causes a first magnetic field via a first of the cell currents, and a second battery cell has a second wound element, consisting of a third electrode layer and a fourth electrode layer, which causes a second magnetic field via a second of the cell currents, wherein the first and the second wound elements are arranged relative to each other such that the first magnetic field counteracts the second magnetic field in the case of the first and second cell current being rectified, wherein the battery pack additionally comprises a magnetic field sensor which is configured to measure a superimposed field consisting of the first magnetic field and the second magnetic field, and comprises an evaluating unit which is configured to determine a difference between the first and the second cell current from the measured superimposed field.