Motor Vibration Identification Using Reactive Torque Injection
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Solution Overview
Problem
Existing methods for reducing vibrations in electrical motors, such as design modifications and frequency skip functions, are costly, time-consuming, and can cause operational halts, especially when natural frequencies change due to wear and tear, leading to instability and dynamic stability issues.
Innovation Solution
A method involving a frequency converter that injects a compensation torque reference to suppress vibrations, using an adaptive closed-loop control strategy to identify and adjust gain and phase responses of the motor system, allowing for optimal reactive torque injection to counteract vibrations without mechanical modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If design modifications are made to alter natural frequency modes, then vibration problems are resolved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent replaces mechanical design modifications with an electrical control system. A frequency converter injects oscillating reactive torque into the motor to generate counter-forces that suppress vibrations at critical speeds, eliminating the need for mechanical redesign of the motor assembly or mounting structure.
Solution Approach 2:
The patent changes the electrical parameters of the motor system by injecting oscillating reactive torque through a frequency converter. The torque magnitude and frequency are dynamically adjusted to match the motor's operating conditions and natural frequencies, providing adaptive vibration suppression without physical modifications.
2Object-affected harmful factors
If frequency skip functions are used to prohibit operation at critical speeds, then vibration is reduced, but operational flexibility and productivity decrease
Solution Approach 1:
The patent converts the harmful vibration phenomenon into a beneficial effect by injecting oscillating reactive torque at the same frequency as the natural vibration. This creates counter-forces that actively suppress the vibrations, allowing the motor to operate smoothly through critical speeds rather than avoiding them.
Solution Approach 2:
The patent implements a dynamic vibration suppression system where the frequency converter continuously adjusts the oscillating reactive torque based on real-time motor operating conditions. The torque magnitude and frequency adapt to changing load and speed conditions, maintaining effectiveness across the entire operating range.
3Measurement precision
If mechanical wear and bearing degradation occur, then natural frequency changes, but measurement and adjustment processes are costly and time-consuming
Solution Approach 1:
The patent enables the motor system to self-identify its natural frequency through the vibration suppression control process. By sweeping through a frequency range and detecting the resonant response, the system automatically determines the current natural frequency without external measurement equipment or manual intervention, adapting to changes caused by wear and degradation.
Solution Approach 2:
The patent implements feedback control where vibration sensors monitor the motor's vibrational response in real-time. The control system uses this feedback to identify natural frequency changes and automatically adjusts the oscillating reactive torque parameters to maintain effective vibration suppression, creating a closed-loop adaptive system.
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 effectively reduces mechanical vibrations, increases the operating speed range of the motor, extends bearing lifetime, and minimizes structural noise, while avoiding the need for mechanical modifications.
Implementation Method 1
A frequency converter is used to generate an oscillating reactive torque which is injected into the electric motor
Implementation Method 2
the natural frequency being the frequency at which the oscillating reactive torque produces a maximum amplitude of a vibration-related parameter
Data Source
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AI summary
A method of identifying parameters of a motor system comprising an electric motor assembly and a control system, for vibration reduction in the electric motor assembly, the method comprising: a) sweeping a frequency of an oscillating reactive torque injected into the electric motor, b) determining a natural frequency of the motor system, the natural frequency being the frequency at which the oscillating reactive torque produces a maximum amplitude of a vibration-related parameter obtained based on vibration-related measurements by sensors mounted to the electric motor, c) incrementally increasing a magnitude of reactive torque oscillating at the natural frequency, injected to the electric motor, d) obtaining a magnitude of the vibration-related parameter for each magnitude of the reactive torque injected in step c), and e) determining, for each magnitude of the injected reactive torque, a gain and a phase response of the motor system, the gain being determined based on the magnitude of the injected reactive torque and the corresponding magnitude of the vibration-related parameter, and the phase response being determined based on a phase angle of the injected reactive torque and a phase angle of the corresponding vibration-related parameter.