Flow Meter Digital Temperature Compensation Circuit
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Solution Overview
Problem
Existing thermal flow meters suffer from temperature drift due to manufacturing errors and environmental influences, leading to reduced precision and increased null shifts, as they typically operate in constant current mode without effective temperature compensation.
Innovation Solution
A flow meter with digital temperature compensation, utilizing an operational amplifier, digital potentiometer, and fixed resistors to maintain a constant temperature mode, allowing for automatic temperature adjustment and compensation of manufacturing errors, thereby stabilizing the sensor coil resistance and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermal flow meters operate in constant current mode, then the device complexity is reduced, but temperature drift occurs leading to reduced measurement precision
Solution Approach 1:
The patent changes the operating parameter from constant current mode to constant temperature mode. By maintaining a constant temperature difference across the sensor coils rather than constant current, the system achieves temperature compensation and eliminates temperature drift, thereby improving measurement precision while accepting increased circuit complexity
Solution Approach 2:
The patent implements a feedback mechanism using operational amplifiers and digital potentiometers that continuously monitor and adjust the temperature difference across the sensor coils. This feedback loop compensates for temperature drift in real-time, maintaining measurement precision under varying environmental conditions
2Measurement precision
If manufacturing tolerance is reduced to improve sensor balance, then measurement precision improves, but manufacturing cost and complexity increase
Solution Approach 1:
The patent enables the flow meter to self-compensate for manufacturing imbalances through its constant temperature control system. The feedback mechanism automatically adjusts for sensor unbalance caused by manufacturing tolerances, eliminating the need for ultra-precise manufacturing and manual calibration while maintaining high measurement precision
Solution Approach 2:
The patent replaces mechanical adjustment methods (such as physical trimming or calibration during manufacturing) with an electronic feedback control system. The digital potentiometer and operational amplifier circuitry automatically compensate for manufacturing variations, reducing the need for high manufacturing precision
3Stability of the object's composition
If digital temperature compensation circuit is added, then temperature drift is compensated improving stability, but device complexity increases
Solution Approach 1:
The patent designs the constant temperature control circuit to perform multiple functions: it maintains the temperature difference across sensor coils, compensates for temperature drift, and provides feedback for measurement accuracy. This multi-functionality justifies the added circuit complexity by delivering comprehensive temperature stability and measurement reliability
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 flow meter achieves high precision and stability with a doubled temperature coefficient, maintaining accurate measurements even under rapid temperature changes, outperforming existing products in terms of accuracy and stability.
Implementation Method 1
the temperature coefficient of the sensor can be doubled and even more
Data Source
AI summary
A flow meter is disclosed, which composes an operational amplifier, a digital potentiometer, a sensor coil, and fixed resistors R1, R2 and R3. One end of the coil is connected to the non-inverting input terminal of the amplifier, the other end is grounded. The R1 is connected between the non-inverting input terminal and the output terminal of the amplifier, the inverting input terminal of the amplifier is connected to one end of R2 and R3, the other end of R2 is connected to the output terminal of the amplifier, and the other end of R3 is grounded. The connecting end of R2 and the output terminal of the amplifier is connected to the high side of the potentiometer, the grounded end of R3 is connected to the low side of the potentiometer, and the inverting input terminal of the amplifier is also connected to the sliding end of the potentiometer.