Pump Idle Load Detection Using Synchronous Motor Torque Measurement
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Solution Overview
Problem
Existing water-bearing household appliances face challenges in accurately determining idle load conditions of pumps, which affects engine friction, temperature, and delivery pressure, leading to inefficient operation and potential errors.
Innovation Solution
A method involving a variable-speed, permanently excited synchronous motor and a control unit that measures torque and current intensity to determine idling conditions, extrapolating no-load torque for improved accuracy, and adjusting pump speed accordingly to optimize operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the pump is switched off when water is almost completely pumped out, then energy consumption is reduced, but the determination of idle load conditions becomes inaccurate due to engine friction, temperature, and delivery pressure variations
Solution Approach 1:
The patent applies preliminary action by determining the idle load condition before the pump is switched off. The control unit measures torque and current intensity at different pump speeds to establish the idle load condition (zero delivery flow) in advance, allowing for accurate determination of when the pump should be switched off based on pre-established baseline values, thus resolving the contradiction between energy reduction and measurement accuracy
Solution Approach 2:
The patent utilizes parameter changes by measuring torque and current intensity at varying pump speeds to identify the idle load condition. By changing the pump speed parameter and observing the corresponding torque and current values, the system establishes baseline idle load characteristics that account for engine friction, temperature, and delivery pressure variations, enabling accurate idle load determination for energy-efficient operation
2Measurement precision
If torque and current intensity are measured to determine idle conditions, then idle load determination accuracy is improved, but device complexity increases due to additional measurement requirements
Solution Approach 1:
The patent applies universality by utilizing the existing synchronous motor for multiple functions: it serves as both the pump drive motor and as a measurement device. The torque and current intensity measurements are obtained from the motor's electrical parameters during normal operation, eliminating the need for separate dedicated measurement devices. This multi-functional approach improves idle load determination accuracy while avoiding additional device complexity
Solution Approach 2:
The synchronous motor performs self-service by providing its own measurement data for idle load determination. The control unit utilizes the motor's inherent electrical characteristics (current intensity, torque) to monitor and determine the pump's idle load condition without requiring external measurement systems. This self-service mechanism achieves high measurement precision without increasing overall device complexity
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 method enables precise determination of idle power, reducing energy consumption and improving error detection in pumps, allowing for better flow rate management and error state identification in household appliances.
Implementation Method 1
a variable-speed, permanently excited synchronous motor as the pump drive motor
Implementation Method 2
a pump for conveying aqueous liquids
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a method for operating a water-bearing household appliance 1, which comprises a pump 18 for conveying an aqueous liquid 7, a variable-speed, permanent magnet synchronous motor as a pump drive motor 26, and a control unit 8, comprising the steps (a) setting a pump speed n to a value nl at which a nozzle pressure p of the pump 18 is insufficient to generate a flow rate Q; and (b) measuring a torque M of the pump 18 as a measure of an idle torque Ml. The invention also relates to a water-bearing household appliance 1 suitable for carrying out the method.