Semi-Modular Battery BMS for Fault Isolation and Low-Power Sensing
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Solution Overview
Problem
Existing lithium battery management systems face challenges in accurately measuring high currents, balancing currents among components, and ensuring reliable protection against short circuits, overcurrents, and deep discharges, often requiring complex architectures with external components that increase costs and complexity.
Innovation Solution
A semi-modular battery management system (BMS) with independent detection circuits for each line of lithium cells, using MOSFETs for cut-off and load control, and a digital integrator for current measurement, allowing precise voltage and temperature monitoring to isolate faulty blocks without affecting the entire battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional current measurement methods (shunt, magnetic measurement, thermal effect) are used, then current can be measured, but static consumption is high requiring standby and active modes which complicates short-circuit protection
Solution Approach 1:
The patent extracts the current measurement function from traditional high-consumption methods (shunt, magnetic sensors, thermal effects) and replaces it with a voltage-based measurement approach. By measuring voltage across the battery terminals and using the known battery impedance, the system calculates current without requiring continuous activation of high-power measurement components, thus reducing static consumption while maintaining measurement capability.
Solution Approach 2:
The patent introduces an intermediary calculation method where current is not measured directly but derived through voltage measurement and impedance-based computation. This intermediary approach allows the system to obtain accurate current data while keeping measurement circuits in low-power standby mode, eliminating the need for high-consumption direct measurement hardware to remain continuously active.
2Adaptability or versatility
If a single BMS controls all accumulators in series, then voltage and current can be monitored globally, but adding accumulators requires resizing components and current balancing becomes difficult
Solution Approach 1:
The patent segments the battery management system into independent modular units, each capable of managing a specific string of accumulators. Each module contains its own protection circuitry and control logic, allowing accumulators to be added or removed from individual strings without affecting other strings. This modular architecture eliminates the need to resize components when expanding battery capacity and simplifies current balancing by confining it to individual modular segments.
Solution Approach 2:
The patent designs universal modular BMS units that can manage any configuration of accumulators through standardized interfaces. Each module is designed to handle a range of voltage and current specifications, allowing the same basic module design to serve multiple battery configurations without requiring custom component sizing. The modular units can be combined in series or parallel to create batteries of various capacities while maintaining consistent component specifications across all modules.
3Reliability
If cut-off device must withstand very high short-circuit current (e.g., 2000 A), then protection is provided, but semiconductors capable of withstanding this current are not common and several lower current components must be connected in parallel requiring oversizing
Solution Approach 1:
The patent changes the electrical parameters of the cut-off device by selecting semiconductor components with higher voltage ratings and lower on-resistance values. By operating at optimized voltage and current parameters within the component's safe operating area, the system achieves reliable short-circuit protection using fewer, smaller components. The low on-resistance allows individual components to handle higher current densities without excessive power dissipation, eliminating the need for large parallel arrays of components.
Solution Approach 2:
The patent employs multiple low-cost, low-power semiconductor cut-off devices in parallel, where each device is designed to handle a portion of the total current. Rather than using expensive high-current components, the system uses several inexpensive low-current devices that can be easily replaced if needed. The modular nature of these components simplifies current distribution and eliminates the need for complex current balancing circuitry, as each component operates independently within its designed parameters.
Data Source
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AI summary
The present invention relates to a system for managing accumulator batteries (BMS) of a semi-modular element comprising a plurality of lithium cell elements connected in series to form a line, and comprising at least two parallel lines constituting the semi-modular element, and at least one detection circuit characterised in that the detection circuit comprises at least one discharge or short-circuit detection device and at least one device for monitoring the voltage and temperature of at least one, and preferably all, of the cell elements, the detection circuit controlling a circuit breaker device comprising one cut-off member per line.