Reactive Torque Injection for Electric Motor Vibration Damping
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Solution Overview
Problem
Existing methods to mitigate vibrations in electrical motors, such as design modifications and frequency skip functions, are costly, time-consuming, and not feasible in all applications, especially due to changes in natural frequencies caused by mechanical wear and tear.
Innovation Solution
A method involving a frequency converter that injects a reactive torque reference to counteract mechanical vibrations, using sensors to measure and control the torque to suppress vibrations at critical frequencies 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 reduction is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces mechanical design modifications with an electrical control system. A frequency converter generates a reactive torque reference signal that is injected into the motor control system, creating counter-forces in the air gap to suppress vibrations. This substitutes complex mechanical alterations with an electrical control approach, reducing device complexity while maintaining vibration reduction effectiveness.
Solution Approach 2:
The patent introduces a frequency converter as an intermediary device between the power source and the motor. This intermediary generates and injects the reactive torque reference signal, acting as a mediator that suppresses vibrations without requiring direct mechanical modifications to the motor structure. The frequency converter serves as the intermediate control element that resolves the contradiction.
2Object-affected harmful factors
If frequency skip functions are used to prohibit operation at critical speeds, then vibrations are reduced, but productivity and operating speed range decrease
Solution Approach 1:
The patent transforms the static frequency skip approach into a dynamic vibration suppression system. Instead of prohibiting operation at critical speeds, the system dynamically generates reactive torque references that adapt to the motor's operating conditions. This allows the motor to operate continuously across the full speed range, including critical speeds, while actively suppressing vibrations through real-time control adjustments.
Solution Approach 2:
The patent changes the control parameter from binary frequency skipping to continuous reactive torque injection. The frequency converter dynamically adjusts the reactive torque reference magnitude and phase based on the motor's operating speed and vibration characteristics. This parameter change enables operation at all speeds while maintaining vibration suppression, thereby preserving productivity and expanding the effective operating speed range.
3Object-affected harmful factors
If mechanical modifications are made to reduce vibrations, then vibration performance improves, but manufacturing cost and time increase
Solution Approach 1:
The patent replaces costly mechanical modifications with an electrical control solution. The frequency converter and control system generate reactive torque references that suppress vibrations through electromagnetic forces in the air gap. This eliminates the need for expensive mechanical alterations such as changing bearing types, modifying the mounting assembly, or altering the motor structure, thereby significantly reducing manufacturing costs while maintaining vibration reduction performance.
4Measurement precision
If natural frequency measurements and skip frequency modifications are performed, then vibration suppression accuracy improves, but maintenance time and operational downtime increase
Solution Approach 1:
The patent enables the motor system to self-adjust and suppress vibrations in real-time without requiring external measurement and modification interventions. The frequency converter continuously generates reactive torque references based on the motor's operating conditions, automatically adapting to changes in natural frequency due to mechanical wear and tear. This self-service capability eliminates the need for periodic shutdowns, measurements, and manual adjustments, thereby reducing maintenance time and operational downtime while maintaining accurate vibration suppression.
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 costly mechanical adjustments.
Implementation Method 1
This additional torque generates counter forces in the air gap of the machine which leads to suppression of machine vibrations
Data Source
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AI summary
A method of reducing mechanical vibrations of a motor system including an electric motor, the method comprising: a) receiving a vibration-related signal based on measurements by one or more sensors mounted on the electric motor, b) generating a reactive torque reference based on the vibration-related signal, and c) controlling the electric motor based on the reactive torque reference and a main torque reference to counteract the mechanical vibrations.