Current Sensor Calibration via Precharge Phase
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Solution Overview
Problem
Current methods for monitoring and calibrating current sensors in battery management units of hybrid and electric vehicles are inefficient, as they require additional hardware and cannot accurately assess the quality of measurement data without it, leading to potential defects and accelerated battery aging.
Innovation Solution
A method that uses a pre-charging phase with a known pre-charging current, either exponential or constant, to compare measured values from current sensors with expected values, allowing for calibration and plausibility checks without additional components, using software in the battery management unit to assess sensor quality and correct amplification factors and offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional hardware components are used for sensor calibration and monitoring, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The current sensor calibration and monitoring is performed using existing system components (power supply unit, battery, and control unit) without requiring additional dedicated calibration hardware. The system uses its own operational characteristics (pre-charging current profiles) to self-calibrate and verify sensor accuracy, eliminating the need for external calibration equipment.
Solution Approach 2:
The pre-charging power supply unit serves multiple functions: it limits inrush current during system startup, provides a known current profile for sensor calibration, and enables sensor functionality verification. This multi-functional approach allows the same hardware to serve both protective and calibration purposes, avoiding additional dedicated calibration hardware.
2Device complexity
If sensor calibration and monitoring are performed without additional components, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The system performs sensor calibration during the pre-charging phase before normal operation begins. The known pre-charging current profile is used to establish baseline measurements and calculate correction factors (amplification and offset) in advance, ensuring accurate measurements are ready before the sensor is needed for critical battery monitoring during normal operation.
Solution Approach 2:
The control unit continuously monitors the relationship between the known pre-charging current and the sensor's measured current, calculating amplification factors and offset corrections. This feedback mechanism allows the system to automatically adjust and verify sensor accuracy using the predictable pre-charging current profile as a reference standard.
3Measurement precision
If pre-charging phase is implemented with known current profile, then sensor calibration accuracy is improved, but loss of time increases
Solution Approach 1:
The pre-charging phase is designed to provide just enough calibration data points needed for accurate sensor calibration without extending unnecessarily. The system uses the predictable exponential current profile during this phase to obtain sufficient measurement data for calculating amplification and offset corrections, then transitions to normal operation once calibration is complete.
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 method enables cost-effective calibration and defect detection of current sensors, ensuring accurate measurement data and prolonging battery life by preventing excessive electrical power usage, thereby reducing battery aging.
Implementation Method 1
a pre-charging resistor (18) connected in parallel to the inverter (20) and the electric motor (22) and used to limit a pre-charging current (I) flowing through the battery (100) during a pre-charging phase
Implementation Method 2
A smoothing capacitor (24) is connected in parallel with the inverter (20) and the electric motor (22) and is used to smooth a high-frequency voltage ripple generated by the inverter (20)
Data Source
Figure 1~2
AI summary
The invention describes a method for checking the proper method of operation of a current sensor (26, 28) which is designed to measure a battery current. During a precharge phase (32) which begins at a time (34) at which at least one electrical component (20, 22, 24) is connected to a battery (100) and during which the electrical component (20, 22, 24) is precharged by a precharge current, at least one measured value provided by the current sensor is compared with an expected current value determined from an expected temporal profile of the precharge current. The invention also describes a computation unit and a battery (100) which are designed to carry out the method according to the invention.