Sensorless Displacement Pump Pressure Control via Motor Torque
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Solution Overview
Problem
Conventional displacement pump arrangements face challenges in dynamic control and require multiple components, making it difficult to maintain pressure at zero delivery rate and prolong the time needed to adjust pressure when the slide valve is opened, while also relying on separate pressure relief valves to avoid overpressures.
Innovation Solution
A method that uses a control device to register state values from the drive motor, such as torque and position, to control the displacement pump without sensors, allowing for variable rotational speed control and integration of frequency converters and control devices, using motor torque-final pressure dependency to determine and control final pressure, and enabling startup against a closed slide valve using a sensorless synchronous reluctance motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate pressure relief valves are used to avoid overpressures and dissipate pressures quickly, then pressure safety is improved, but device complexity increases
Solution Approach 1:
The patent combines the frequency converter and control device into a single integrated unit. The control device performs both frequency conversion functions and control functions (including pressure relief control) that were previously handled by separate components. This merging eliminates the need for separate pressure relief valves while maintaining pressure safety through integrated control capabilities.
2Ease of operation
If conventional control methods are used with separate frequency converter and control device, then control functionality is achieved, but control dynamics are limited
Solution Approach 1:
The patent integrates the frequency converter and control device into one unified system. This integration enables faster and more dynamic control responses because the control device can directly and immediately adjust the frequency converter's parameters without communication delays or coordination overhead between separate components.
3Measurement precision
If sensors are used to measure controlled variables for control, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The control device utilizes state values (such as current, voltage, and operational parameters) that are already available from the drive system's own measurements and calculations. Instead of requiring additional external sensors to measure controlled variables, the system leverages its existing sensing capabilities and computational resources to determine control variables through calculations based on available state values.
4Stability of the object's composition
If pressure relief valves are used to maintain pressure control, then pressure stability is improved, but response time to adjust pressure when slide valve opens is prolonged
Solution Approach 1:
The integrated control device dynamically adjusts control parameters in real-time based on current system state. When the slide valve opens, the control device can immediately respond by adjusting frequency converter parameters to maintain pressure stability, providing a much faster response than mechanical pressure relief valves which rely on pressure differential activation and mechanical movement.
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
This approach enhances control dynamics, reduces the number of components needed, allows for immediate pressure maintenance at zero delivery rate, and enables precise control of final pressure and fluid volume without sensor measurements, detecting incomplete filling and ensuring accurate fluid quantity calculation.
Implementation Method 1
an electric drive motor provided with stator and rotor
Implementation Method 2
a frequency converter
Data Source
AI summary
A displacement pump arrangement, method for operating the displacement pump arrangement and a control device for controlling the displacement pump arrangement provide rotational-speed-variable control of an expeller pump unit for feeding a fluid. The arrangement includes an expeller pump and a drive, the drive being composed of an electric drive motor and a frequency converter, and a control device. The control device controls a state value such as a final pressure of the expeller pump a setpoint value. The control device detects state values of a control variable are supplied by the drive, in particular relating to the position, rotational speed and torque of the drive motor, and adjusts the displacement pump output to reach the setpoint value without using sensors.