Shunt Battery Sensor Layout for Temperature-Independent Current Sensing
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Solution Overview
Problem
Existing battery sensors face challenges in accurately measuring battery current due to high temperature dependence of the resistance measuring section, caused by the significant difference in temperature coefficients between the resistance alloy and connecting parts, leading to errors in temperature determination and current measurement.
Innovation Solution
A battery sensor design with a plate-shaped resistance element and strategically positioned contact points on connecting parts, where the current flows orthogonally to the resistance element's longitudinal axis, allowing for compensation of temperature-related resistance changes, effectively creating a temperature-independent voltage divider to minimize temperature dependence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resistance of the measuring section is determined from the resistance of the resistance alloy and the partial resistances of the connecting parts, then the current measurement can be performed, but the temperature coefficient of the measuring section deviates from and is greater than the temperature coefficient of the resistance material
Solution Approach 1:
The contact points are arranged offset transversely to the longitudinal axis of the resistance element, introducing a transverse dimension to the current path. This dimensional change allows the current to flow through sections of connecting parts with different temperature coefficients, enabling compensation of the overall temperature dependence of the measuring section
Solution Approach 2:
The positions of the contact points are specifically selected to change the distribution of current flow through different sections of the connecting parts. By adjusting this geometric parameter, the temperature-related resistance changes in different sections are balanced to compensate for each other, reducing the overall temperature coefficient of the measuring section
2Measurement precision
If temperature measurement and mathematical corrections are implemented to compensate for temperature dependence, then current measurement accuracy can be maintained, but the device complexity and computational burden increase
Solution Approach 1:
The measuring section structure itself provides temperature compensation through its geometric design. The offset arrangement of contact points creates a self-compensating system where temperature-related resistance changes in different sections automatically balance each other, eliminating the need for external temperature sensors and computational corrections
Solution Approach 2:
The temperature compensation function is extracted from the electronic control system and embedded directly into the physical structure of the measuring section. This structural extraction eliminates the need for separate temperature measurement devices and mathematical correction algorithms in the microcontroller
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 design reduces temperature-related errors in current measurement, eliminating the need for temperature measurement and mathematical corrections, enhancing accuracy and reducing computational and storage burdens on the microcontroller, while allowing real-time operation.
Implementation Method 1
The current measurement is carried out in accordance with Ohm's law using the shunt principle, which means that the current to be measured is converted into a voltage via a suitable resistor, the so-called shunt.
Implementation Method 2
An important feature of the resistance alloy is a low temperature coefficient, that is, the change in the resistance of the resistance alloy with a change in the temperature of the resistance alloy is as small as possible
Data Source
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AI summary
The invention relates to a battery sensor, in particular for a vehicle battery, having two connection parts (3a, 3b) which are electrically conductively connected to each other via a resistor element (1), there being one contact point (2a, 2b) on each of the connection parts (3a, 3b), the direction of the longitudinal axis of at least one of the connection parts (3a, 3b) deviating from the direction of the longitudinal axis of the resistor element or shunt (1). The position of the contact points (2a, 2b) is selected transversely to the longitudinal axis of the resistor element or shunt such that the electrical resistances (R4, R5, R6) of sections of the connection parts (3a, 3b) through which the current flows transversely to the longitudinal axis (y-direction) of the resistor element or shunt are dimensioned such that a temperature-induced change in the electrical resistances (R4, R5, R6) compensates for a temperature-induced change in electrical resistances (R3) formed by sections of the connection parts (3a, 3b) through which current flows in the direction of the longitudinal axis of the resistor element or shunt.