Electric Motor Speed Curve for Torque-Limited High-Speed Operation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional systems inaccurately assume that electric motors can maintain their rated power beyond the rated speed, leading to mismatches between calculated and actual speeds under load, particularly at high operating speeds, affecting the efficiency and effectiveness of high-speed lifting systems.
Innovation Solution
A method to determine the maximum operating speed of an electric motor by operating it at varying torques, constructing curves based on actual measurement points, and using a coefficient and polynomial functions to predict speed under different load conditions, ensuring safe and effective operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional systems assume the motor can consistently deliver its rated power regardless of speed, then the calculation is simple, but the actual speed under load does not match the calculated speed
Solution Approach 1:
The patent applies preliminary action by pre-determining the maximum speed curve through offline measurements and curve fitting before actual operation. The system performs speed measurements at various torques, fits a polynomial curve to the data, and stores the maximum speed curve for later use. This eliminates the need for complex real-time calculations during motor operation while ensuring accurate speed predictions under load.
2Productivity
If the motor operates at speeds higher than rated speed, then the lifting efficiency improves, but the motor cannot maintain its rated power
Solution Approach 1:
The patent applies dynamics by transitioning from a static rated power assumption to a dynamic maximum speed curve that adapts to varying torque conditions. The system determines the maximum speed curve through measurements at different torque levels and uses polynomial fitting to create a dynamic model that accurately represents motor performance across the entire operating range, enabling reliable high-speed operation.
Solution Approach 2:
The patent applies parameter changes by shifting from using a constant rated power parameter to using a variable maximum speed curve parameter. The system measures speed at multiple torque points, fits a polynomial curve to these measurements, and uses the resulting curve as the governing parameter for speed prediction. This allows the system to accurately capture the motor's performance characteristics at speeds both above and below the rated speed.
3Measurement precision
If polynomial fitting is used to determine the maximum speed curve, then the speed prediction accuracy improves, but the computational process becomes more complex
Solution Approach 1:
The patent applies preliminary action by performing the complex polynomial fitting process offline before actual motor operation. The system collects speed measurements at various torque levels, fits the polynomial curve to these data points, and stores the resulting maximum speed curve. This eliminates the need for complex real-time curve fitting during operation, reducing computational complexity while maintaining high prediction accuracy.
Data Source
AI summary
A method that involves determining the maximum operating speed of an electric motor under varying torque conditions, specifically at speeds surpassing its rated speed. Initially, the motor is operated at its highest speed across different torque values, establishing a data set of real measurement points. These points illustrate the relationship between the maximum motor speed and the applied torque. A coefficient (COF), ranging from 0 to 1 and dependent on motor characteristics, is selected. Two curves are then established: the first for lower maximum speeds, represented byΩref=COFPnomTmeas,and the second for torques below a defined limit torque Tlim expressed asΩref=COFPnomf(Tmeas),where ƒ is a polynomial function derived from the measurement points. The appropriate curve is then used to ascertain the maximum motor speed for a given torque, based on whether the torque is greater or lesser than Tlim.