Voltage Divider Switching for Battery Measurement Overvoltage Protection
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Solution Overview
Problem
Existing voltage measurement circuits for energy storage devices face issues of overvoltage applied to measurement units and malfunction of field-effect transistors (FETs), particularly when the voltage of energy storage devices exceeds allowable limits or falls below threshold voltages, leading to unreliable voltage measurements.
Innovation Solution
A voltage measurement circuit design that incorporates voltage dividing circuits with N-channel and P-channel FETs strategically positioned between resistors, allowing the FETs to operate based on ground potential, thereby preventing overvoltage and malfunction by ensuring proper switching and voltage isolation during measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voltage dividing circuit is used to measure high voltage energy storage devices, then voltage measurement capability is improved, but overvoltage may be applied to the measurement unit when device voltage exceeds allowable limits
Solution Approach 1:
The patent introduces FETs as intermediary switching devices between the voltage dividing circuit and measurement unit. These FETs act as protective intermediaries that can rapidly disconnect the measurement unit from high voltage nodes when overvoltage conditions are detected, preventing damage while allowing normal measurement operations to proceed through the voltage dividing circuit
2Loss of energy
If switching devices are used to cut off current in voltage dividing circuits, then power consumption is reduced, but FET malfunction may occur when voltage exceeds threshold levels
Solution Approach 1:
The patent applies different channel types (N-channel and P-channel FETs) to different stages of the voltage dividing circuit based on local voltage conditions. N-channel FETs are used in stages where the voltage potential allows proper gate control, while P-channel FETs are used in higher voltage stages, ensuring each switching device operates within its optimal voltage range and prevents malfunction
Solution Approach 2:
The patent changes the electrical parameters (threshold voltage, channel type) of the FETs according to the specific voltage conditions of each stage in the voltage dividing circuit. This parameter adaptation ensures that each FET can be properly controlled and switched without malfunction, even when operating at different voltage levels
Data Source
AI summary
A voltage measurement circuit includes: voltage dividing circuits that divide voltages of energy storage devices, in respective stages connected in series; switches that cut off the currents of the voltage dividing circuits in the respective stages, and a measurement unit that measures the voltages of the energy storage devices in the respective stages based on outputs of the voltage dividing circuits in the respective stages. The voltage dividing circuits in the respective stages each have a first resistor connected to the ground and a second resistor connected to a positive electrode of the corresponding energy storage device. The switch in a predetermined-number stage among the switches in the respective stages is an N-channel field-effect transistor (FET) having a source connected to the first resistor and a drain connected to the second resistor, and the source of the FET is a voltage output terminal with respect to the measurement unit.