Motor NTC Sensing Circuit With Switched Pull-Up Linearization
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Solution Overview
Problem
Conventional temperature sensing circuits using NTC thermistors face challenges in accurately measuring temperatures due to non-linear characteristics, requiring complex control methods and software logic to vary pull-up resistances.
Innovation Solution
A temperature sensing device that automatically adjusts the pull-up resistance without software design, utilizing a comparator to change the resistance based on voltage comparisons with reference voltages, ensuring improved linearity and accuracy across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional temperature sensing circuit uses a fixed pull-up resistance with an NTC thermistor, then the circuit structure remains simple, but temperature sensing linearity deteriorates in specific temperature sections
Solution Approach 1:
The patent implements dynamic switching of pull-up resistance values based on temperature ranges. The circuit automatically selects between a first pull-up resistance (for low temperature) and a second pull-up resistance (for high temperature) using comparison units that monitor the thermistor voltage and activate switches accordingly. This dynamic adaptation resolves the contradiction by maintaining measurement precision across the full temperature range while keeping the circuit structure relatively simple through automated switching.
Solution Approach 2:
The patent changes the resistance parameter of the pull-up resistor based on temperature conditions. By providing multiple pull-up resistance values and switching between them according to the detected temperature range, the system optimizes the voltage-output characteristics for different temperature sections. This parameter change strategy improves temperature sensing linearity without requiring a completely complex circuit design.
2Measurement precision
If an active element such as a transistor is added to vary the pull-up resistance, then temperature sensing linearity at high temperature improves, but device complexity and control method complexity increase
Solution Approach 1:
The patent segments the temperature measurement range into multiple sections (low temperature and high temperature ranges) and assigns different pull-up resistance values to each segment. Comparison units divide the detection task by comparing the thermistor voltage against reference voltages, and switches selectively connect appropriate pull-up resistors for each temperature segment. This segmentation approach improves high-temperature sensing linearity while managing device complexity through modular organization.
Solution Approach 2:
The patent implements feedback control where comparison units continuously monitor the voltage output from the NTC thermistor and automatically adjust the pull-up resistance selection based on the detected temperature range. The feedback loop ensures the appropriate resistance value is maintained for optimal linearity in the current temperature condition, improving measurement precision without requiring manual intervention or complex external control.
3Measurement precision
If software logic is added to control the active element for varying pull-up resistance, then temperature sensing accuracy improves, but ease of operation deteriorates due to complicated control method design
Solution Approach 1:
The patent implements a self-service control mechanism where the temperature sensing circuit automatically selects the appropriate pull-up resistance without external software intervention. The comparison units autonomously monitor the thermistor voltage and activate the corresponding switches based on predetermined reference voltages, enabling the system to self-adjust to optimal resistance values for the current temperature range. This eliminates the need for complex software logic and simplifies operation while maintaining high measurement accuracy.
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
The solution enhances temperature sensing accuracy and linearity at all temperatures, simplifying the control method and eliminating the need for software design, while maintaining a relatively simple device structure.
Implementation Method 1
a negative temperature coefficient (NTC) thermistor installed on a motor
Implementation Method 2
a comparison unit including a comparator for comparing the voltage value output from the voltage output unit with a reference voltage
Data Source
AI summary
A temperature sensing device and a temperature sensing device for a vehicle are provided. The temperature sensing device includes: a negative temperature coefficient (NTC) thermistor installed on a motor; a pull-up resistor connected to one end of the NTC thermistor, the pull-up resistor having a resistance that varies depending on a temperature inside the motor; a voltage output unit to output a voltage based on a change in resistance of the NTC thermistor according to a change in temperature; and a comparison unit including a comparator for comparing the voltage value output from the voltage output unit with a reference voltage, wherein the comparison unit changes the resistance of the pull-up resistor unit based on an output of the comparator.