Torque Estimation in Running Motors via Electrical Power Analysis
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Solution Overview
Problem
Existing methods for measuring torque in running motors are either mechanically intrusive, disruptive to the motor's operation, or expensive, and indirect methods require non-running conditions or learning periods.
Innovation Solution
A method that estimates torque by measuring total electrical active power and rotor speed without interrupting the motor's operation, using Fourier analysis and symmetrical decomposition of the electrical power components to calculate electromechanical axle torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque sensors are mechanically coupled to the motor shaft, then torque measurement is achieved, but the system becomes mechanically complex and the sensor interferes with motor operation
Solution Approach 1:
The patent replaces mechanical torque sensors with an electrical measurement system. Torque is calculated indirectly by measuring electrical parameters (current, voltage, frequency) and processing them through digital signal processing and mathematical models, eliminating the need for physical sensors on the motor shaft.
Solution Approach 2:
The patent introduces electrical parameters as an intermediary medium to measure torque. Instead of directly measuring mechanical torque, the system measures electrical current and voltage which are then transformed through mathematical relationships to derive torque values, acting as a non-intrusive mediator.
2Measurement precision
If indirect measurement methods using Steinmetz equivalent circuit are used, then torque can be determined, but the motor must be in non-running conditions which disrupts normal operation
Solution Approach 1:
The patent enables continuous torque measurement during normal motor operation. By using real-time electrical parameter measurements and processing, the system maintains uninterrupted motor operation while continuously providing torque data, eliminating the need to stop the motor for measurements.
Solution Approach 2:
The patent performs preliminary calibration during motor startup or idle periods to establish baseline parameters, then uses these pre-established parameters during normal operation to enable continuous torque measurement without requiring the motor to be stopped for each measurement.
3Measurement precision
If mechanical torque sensors are used in high-speed spindle applications, then torque measurement is obtained, but the sensor introduces imbalance and interferes with motor operation
Solution Approach 1:
The patent eliminates mechanical sensors from the high-speed rotating system by substituting them with electrical measurement techniques. Torque is derived from electrical parameters measured at the motor terminals, completely avoiding the introduction of mechanical imbalance and interference in high-speed spindle applications.
4Measurement precision
If digital signal processing analysis of motor start-up current is used, then torque information can be obtained, but a learning period is required and normal operation is interrupted
Solution Approach 1:
The patent enables continuous torque estimation during normal motor operation by processing electrical parameters in real-time. The system does not require stopping the motor or implementing a separate learning period, as torque can be continuously calculated from operational electrical measurements.
Data Source
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AI summary
A method of estimating the torque of an axle of a running motor, comprising receiving data indicative of the total electrical active power, P, supplied to the motor, determining the electromechanical power, Pem, supplied to the axle using the data indicative of the total electrical active power, P, receiving data indicative of a rotor speed, nr, or rotor frequency, fr, of the axle, determining an angular rotor frequency, ωr, of the axle using the data indicative of rotor speed, nr, or rotor frequency, fr, of the axle, and determining electromechanical axle torque, Tem, using the determined electromechanical power, Pem, and the determined angular rotor frequency, ωr.