Battery Management System Current Detection Failure Diagnosis
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Solution Overview
Problem
Current battery management systems face challenges in accurately detecting failures in current detecting circuits with shunt resistors without the need for additional hall sensors, which are costly and complex.
Innovation Solution
A battery management system that includes a current detecting circuit with a shunt resistor and a bidirectional switch comprising charging and discharging FETs, along with a control unit that applies high-level voltages to the FETs to detect voltages and calculate currents using lookup tables to determine circuit failures without a hall sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a hall sensor is added to detect charging/discharging current for failure determination, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent creates a virtual copy of the current measurement function by calculating equivalent current values from voltage measurements across the FETs. Instead of using a physical hall sensor to directly measure current, the system computes a representative current value from easily measurable voltage parameters, achieving accurate current detection without additional sensing hardware.
Solution Approach 2:
The patent introduces voltage measurements across the FETs as an intermediary parameter to indirectly determine current. By measuring voltage drops across known resistance elements (the FETs) and using these as intermediaries to calculate current values, the system avoids direct current measurement while maintaining measurement accuracy.
2Measurement precision
If a hall sensor is added to detect charging/discharging current for failure determination, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent creates a virtual copy of the current measurement function by calculating equivalent current values from voltage measurements across the FETs. Instead of using a physical hall sensor to directly measure current, the system computes a representative current value from easily measurable voltage parameters, achieving accurate current detection without additional sensing hardware.
Solution Approach 2:
The patent replaces expensive hall sensors with inexpensive voltage measurement circuits that utilize existing FET components. By leveraging already-present elements in the power management circuitry and performing computational measurements, the system achieves current detection capability at minimal additional cost.
3Device complexity
If voltage measurements and lookup tables are used to calculate current without a hall sensor, then device complexity is reduced, but measurement precision may deteriorate
Solution Approach 1:
The patent creates a virtual copy of the current measurement function by calculating equivalent current values from voltage measurements across the FETs. Instead of using a physical hall sensor to directly measure current, the system computes a representative current value from easily measurable voltage parameters, achieving accurate current detection without additional sensing hardware.
Solution Approach 2:
The patent replaces physical current sensing mechanisms (hall sensors) with computational methods. By substituting hardware-based current measurement with software-based calculations using voltage measurements and lookup tables, the system reduces hardware complexity while maintaining measurement functionality.
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 reliable detection of current detecting circuit failures without the need for a hall sensor, reducing manufacturing costs and complexity while maintaining accurate current measurement.
Implementation Method 1
the current detecting circuit has a shunt resistor, and detects the charging/discharging current by dividing the measured voltage across the shunt resistor when the charging/discharging current flows through the shunt resistor by the resistance of the shunt resistor
Implementation Method 2
a bidirectional switch including a charging field effect transistor (FET) and a discharging FET connected in series and configured to be installed on the high current path
Data Source
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AI summary
Disclosed is a battery management system, a battery pack including same and a method for determining a failure in a current detecting circuit. The system includes the current detecting circuit configured to detect a reference current representing a current flowing through a high current path of the battery pack, a bidirectional switch including a charging FET and a discharging FET installed on the high current path, and a control unit. The control unit detects a first voltage across the charging FET and a second voltage across the discharging FET while a first high level voltage is applied to a gate of the charging FET and a second high level voltage is applied to a gate of the discharging FET. The control unit determines a failure in the current detecting circuit based on at least one of the first voltage and the second voltage and the reference current.