Electric Motor Winding Current Monitoring for Pump Pressure Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems for monitoring electric motors driving pumps in systems with periodic pressure fluctuations are complex and costly, relying on additional pressure sensors and valves to manage pressure, which can lead to damage and inefficiency.
Innovation Solution
A method that determines the mean value of the winding current within a time interval greater than the period of system-related pressure fluctuations, integrating pressure monitoring into motor control without additional sensors, allowing regulation of average pressure in the delivery circuit based on winding current, and adjusting the motor feed current to maintain optimal pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensors and pressure relief valves are added to monitor and control pressure in the delivery circuit, then pressure monitoring capability is improved, but device complexity and cost increase
Solution Approach 1:
The electric motor performs self-diagnosis by monitoring its own winding current to detect pressure conditions in the delivery circuit. The control unit evaluates current values to determine overload conditions caused by pressure blockages, eliminating the need for external pressure sensors and relief valves.
Solution Approach 2:
The winding current measurement, originally intended only for motor control and protection, is repurposed to also serve as a pressure monitoring indicator. This multi-functional use of existing measurements allows pressure detection without adding dedicated pressure sensing components.
2Reliability
If pressure sensors and pressure relief valves are added to the system, then reliability of pressure detection is improved, but cost increases
Solution Approach 1:
The system uses its own operational parameters (winding current) to detect pressure-related faults, making the detection system self-contained and eliminating costly external pressure sensing components while maintaining reliable fault detection capability.
3Speed
If the time interval for current measurement is shorter than the pressure fluctuation period, then response speed is improved, but measurement accuracy of average pressure deteriorates
Solution Approach 1:
The control unit continuously evaluates current values at regular intervals and uses these periodic measurements to determine the mean current over complete pressure fluctuation cycles. This periodic sampling approach ensures accurate representation of average pressure conditions while maintaining responsive monitoring.
Solution Approach 2:
The control unit continuously monitors winding current and provides feedback to determine overload conditions. By evaluating current values over appropriate time intervals that encompass pressure fluctuation periods, the system accurately detects average pressure conditions and responds to sustained overload situations.
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 simplifies and cost-reduces the control of electric motors by eliminating the need for additional pressure sensors and valves, effectively maintaining constant pressure in the delivery circuit and preventing motor damage through adaptive current regulation.
Implementation Method 1
They are controlled by alternately connecting their windings to create a rotating magnetic field, which in turn generates a mechanical torque acting on the motor's rotor.
Implementation Method 2
To vary the current applied to the windings, the converter operates on the principle of pulse-width modulation.
Implementation Method 3
create a rotating magnetic field, which in turn generates a mechanical torque acting on the motor's rotor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Method for monitoring and controlling an electric motor (2) used to drive a pump (1), which is designed as an electronically commutated external rotor motor. The electric motor has three stator windings (5.1, 5.2, 5.3) which are supplied with current from a DC voltage source (15) via a converter (4). The total winding current is measured by means of a current sensor (16). The output signal of the current sensor (16) is fed to a motor controller (3) and processed there. The motor controller (3) includes a processor (8) which executes a program that is stored on a machine-readable data carrier (7) also associated with the motor controller (8). In this method, current values are measured by the current sensor (16) within a time interval. The motor controller (8) then determines the average value from the measured current values, which is compared with a predefined reference value.If the mean of the measured current values is greater than the specified reference value, a maximum permissible value for the motor supply current specified by the motor control (3) is reduced.