Compressor Sensorless Pressure Control via Motor Counter-Torque
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Solution Overview
Problem
Compressor systems face challenges in controlling pressure within pressure vessels due to the high cost and maintenance requirements of pressure sensors, as well as the need for reliable sensorless control methods.
Innovation Solution
A method and apparatus that estimate the operating state of a compressor system by monitoring electrical quantities, such as mechanical power, to calculate counter-torque proportional to pressure, allowing for sensorless control of rotational speed to maintain desired pressure levels within the pressure vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensor is used to control pressure in the pressure vessel, then pressure control accuracy is improved, but system cost increases and maintenance requirements increase
Solution Approach 1:
The patent replaces the mechanical/physical pressure sensor with an electrical measurement system. By monitoring electrical quantities (current, voltage, power) from the motor and using mathematical models to calculate pressure, the system eliminates the need for physical pressure sensors. This substitution resolves the contradiction by maintaining pressure measurement capability while reducing hardware cost and maintenance requirements.
Solution Approach 2:
The patent introduces electrical quantities as an intermediary to indirectly measure pressure. Instead of directly measuring pressure with a sensor, the system measures electrical parameters (current, voltage, power) that correlate with pressure through the motor's electrical-mechanical conversion. This intermediary approach allows pressure inference without direct pressure sensing, resolving the cost and maintenance contradiction.
2Measurement precision
If a pressure sensor is installed to monitor pressure levels, then pressure monitoring capability is improved, but reliability decreases due to sensor malfunctions and maintenance needs
Solution Approach 1:
The patent eliminates the pressure sensor entirely by substituting electrical measurements with pressure inference. By using electrical quantities (current, voltage, power) and mathematical models to calculate pressure, the system removes the unreliable sensor component while maintaining pressure monitoring capability, thus improving reliability.
Solution Approach 2:
The system uses its own motor's electrical characteristics to infer pressure, making the system self-monitoring without external sensors. The motor's electrical consumption pattern naturally reveals pressure information, allowing the system to self-diagnose pressure levels without relying on separate sensor components that can fail.
3Device complexity
If electrical quantities are monitored to estimate pressure, then system cost is reduced, but measurement precision may deteriorate
Solution Approach 1:
The patent implements feedback by continuously monitoring electrical quantities (current, voltage, power) and using this information to calculate pressure in real-time. The system adjusts motor control based on the estimated pressure, creating a closed-loop control system. This feedback mechanism maintains measurement precision by continuously updating pressure estimates based on actual electrical consumption patterns.
Solution Approach 2:
The patent changes the measurement parameters from direct physical pressure measurement to electrical parameter measurement. By monitoring electrical quantities (current, voltage, power) and using mathematical models to convert these to pressure estimates, the system maintains accuracy while reducing cost. The parameter transformation through mathematical modeling ensures precision is preserved despite the indirect measurement approach.
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
Enables efficient operation of compressor systems without pressure sensors, reducing maintenance costs and improving energy efficiency by accurately controlling pressure levels and preventing unnecessary compressor operation.
Implementation Method 1
The pressure in the pressure vessel causes a counter-torque to the motor. The counter-torque is proportional to the pressure, and may be used for estimating the pressure inside the pressure vessel.
Data Source
Figure 1~2
AI summary
The present disclosure describes a control method for a compressor system that comprises a compressor connected to a pressure vessel and a frequency converter controlling an electric motor of the compressor. In the method, the present operating state is estimated on the basis of a monitored/estimated electrical quantity of the compressor system. The operating state may represent the pressure in the pressure vessel. The pressure in the pressure vessel causes a counter-torque to the motor. The counter-torque is proportional to the pressure and may be used for estimating the pressure inside the pressure vessel. An estimate of a counter-torque may be calculated on the basis of the monitored electrical quantity or quantities.