Multiplexer Voltage Measurement High-Voltage Switch Segmentation
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Solution Overview
Problem
Conventional voltage measurement systems for lithium-ion batteries in vehicles face challenges in maintaining accurate voltage measurement when input voltages exceed the power supply voltage, leading to malfunction of switches and reduced measurement accuracy, and require larger circuit areas when using boost MOS switches to prevent such issues.
Innovation Solution
A multiplexer configuration with separate channels for high-voltage and low-voltage input terminals, utilizing a first switch and third switch that operate even at voltages higher than the power supply voltage, and employing a constant voltage circuit to ensure the first switch operates correctly, while reducing the number of high-voltage capable switches and maintaining accurate voltage measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional switches are used in voltage measurement channels, then circuit area is reduced, but measurement accuracy deteriorates when input voltage exceeds power supply voltage
Solution Approach 1:
The voltage measurement system is segmented into two distinct channels: a first voltage measurement channel for high-voltage battery cells and a second voltage measurement channel for low-voltage battery cells. This segmentation allows each channel to use appropriately configured switches, preventing high-voltage interference from affecting the overall circuit design and measurement accuracy.
Solution Approach 2:
Different switch configurations are applied to different parts of the circuit based on voltage requirements. The first channel uses switches configured to handle voltages exceeding the power supply voltage, while the second channel uses conventional switches matched to the power supply voltage, optimizing both accuracy and circuit area for each local requirement.
2Measurement precision
If boost MOS switches are used to prevent malfunction at high voltages, then measurement accuracy is maintained, but circuit area increases
Solution Approach 1:
The system divides voltage measurement into separate channels, allowing boost MOS switches to be used only where necessary (first channel for high-voltage cells) while conventional switches are used in the second channel, thereby maintaining measurement accuracy only where high-voltage conditions exist without unnecessarily increasing overall circuit area.
Solution Approach 2:
The switch configuration parameter is changed based on the voltage level of the battery cell being measured. For battery cells where voltage may exceed the power supply voltage, switches configured to operate at higher voltages are used; for other cells, standard switches are used, optimizing the balance between measurement accuracy and circuit area.
3Stability of the object's composition
If filters are inserted to prevent voltage swing effects, then power supply stability is improved, but measurement response time increases
Solution Approach 1:
The voltage measurement system is divided into separate channels, allowing the first channel to handle high-voltage measurements with appropriate switch configurations that inherently manage voltage swing effects, while the second channel handles low-voltage measurements with conventional components, reducing the need for extensive filtering and thus maintaining faster response times.
Data Source
AI summary
A multiplexer for voltage measurement includes: a first switch disposed on a first channel extending between at least one high-voltage input terminal and an output terminal; a plurality of second switches respectively disposed on second channels each extending between each of input terminals other than the high-voltage input terminal and the output terminal; and a third switch disposed between a group of the plurality of second switches and an output terminal side end of the first switch. Each of the first switch and the third switch is configured to operate even by a voltage higher than a power supply voltage.