Battery Voltage and Current Detection with Single Isolator
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Solution Overview
Problem
Existing battery systems require multiple isolator modules for accurate voltage and current measurement, increasing complexity and cost, especially in high-voltage applications like electric vehicles, where safety and efficiency are critical.
Innovation Solution
A battery design that uses a single isolator module for both cell voltage and current measurement by integrating a resistor in the current path and an amplifier to measure the voltage across it, allowing synchronous transmission of current data with cell voltages through existing cell voltage detection units, thus eliminating the need for additional isolation components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple isolator modules are used for voltage and current measurement, then measurement accuracy and safety are improved, but device complexity and cost increase
Solution Approach 1:
The patent combines voltage measurement and current measurement functions into a single cell voltage detection unit. The resistor for current measurement is integrated into the same detection unit that measures cell voltages, eliminating the need for separate isolator modules for each measurement type. This merging reduces the total number of isolators while maintaining galvanic isolation for safety.
Solution Approach 2:
The cell voltage detection unit is designed to perform multiple functions: it measures both the cell voltages and the current through the resistor. By making the detection unit universal, the patent eliminates the need for dedicated separate measurement circuits for current, thereby reducing the number of isolator modules required.
2Measurement precision
If multiple isolator modules are used for voltage and current measurement, then measurement accuracy is improved, but manufacturing cost increases
Solution Approach 1:
By merging voltage and current measurement into one detection unit, the patent reduces the bill of materials (fewer isolator modules) and simplifies assembly processes. This directly lowers manufacturing costs while preserving measurement accuracy through the integrated design.
3Measurement precision
If a resistor is added to the current path for current measurement, then current measurement capability is improved, but internal resistance and power loss increase
Solution Approach 1:
The resistor is placed only in the current path where measurement is needed, rather than adding resistance throughout the entire battery system. This localized approach minimizes the impact on overall system performance while enabling accurate current measurement at the specific measurement point.
Solution Approach 2:
The patent uses a very small resistance value (in the micro-ohm range) for the measurement resistor. By changing the resistance parameter to be extremely small, the system achieves current measurement capability while keeping the voltage drop and power loss negligible. The detection unit amplifies the small voltage signal to maintain measurement precision.
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 approach reduces the number of isolator modules required, lowers internal resistance and power loss, and allows cost-effective current measurement while maintaining safety and accuracy across the entire measurement range.
Implementation Method 1
cell voltage detection units (20-1 to 20-n), which are designed to determine cell voltages of the battery cells (10-1 to 10-mn) connected to the respective cell voltage detection unit
Implementation Method 2
The battery has an amplifier (80) connected between the resistor (50) and the selected voltage measurement input of one of the cell voltage detection units (20-1 to 20-n) and designed to amplify a voltage present across the resistor (50)
Implementation Method 3
microcontroller (40) that is galvanically decoupled from the cell voltage detection units (20-1 to 20-n) by a potential isolation device (30)
Implementation Method 4
for current measurement, the battery has a resistor which is arranged in the current path of the battery and is connected in series with the battery cells
Data Source
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AI summary
The invention relates to a battery, comprising a plurality of battery cells connected in series between a positive terminal and a negative terminal, and comprising a plurality of cell voltage detection units (20-1,..., 20-n). Each cell voltage detection unit (20-1,..., 20-n) comprises a plurality of voltage measurement inputs connected to a respective group of the battery cells (10-1,..., 10-n) and is designed to determine cell voltages of the battery cells connected to the respective cell voltage detection unit (20-1,..., 20-n). The cell voltage detection units (20-1,..., 20-n) are connected to each other by a communication bus and furthermore are designed to transmit, via the communication bus, the determined cell voltages to a microcontroller (40), which is galvanically decoupled from the cell voltage detection units (20-1,..., 20-n) by an electrical isolation device (30). According to the invention, the battery comprises a resistor (50), which is connected in series to the battery cells and at least one first connection which is connected to a selected voltage measurement input of one of the cell voltage detection units (20-1,..., 20-n). The invention further relates to a motor vehicle comprising an electric drive motor for driving the motor vehicle, and to a battery according to the invention which is connected to the drive motor.