Electric Motor Active Torque Control for Resonance Vibration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric motors experience severe vibrations when operating at natural frequencies, limiting continuous operation and requiring design modifications to avoid critical speed, which restricts the operational range and can cause harmful vibrations during acceleration and deceleration.
Innovation Solution
An active vibration controller (AVC) is used to determine if the rotor or stator frequency is within a critical range and adjusts the oscillating incremental torque frequency to cancel unwanted vibrations by generating an oscillating torque reference, thereby controlling the motor to mitigate these vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If design modifications are made to alter natural frequency modes to avoid critical speed, then vibrations during continuous operation are reduced, but the operational range is restricted and the machine cannot operate above critical speed
Solution Approach 1:
The patent applies dynamics by making the control system adaptive and variable rather than fixed. The controller dynamically adjusts the torque reference based on real-time detection of critical speed conditions, allowing the system to operate across a wider range including above critical speed by actively managing vibrations as they occur rather than preventing them through fixed design constraints
Solution Approach 2:
The patent changes the parameter of torque reference by adding an oscillating component at the critical speed frequency. This parameter modification allows the system to counteract resonant vibrations actively, enabling operation above critical speed while maintaining vibration control, thus expanding the operational range without sacrificing reliability
2Object-affected harmful factors
If the critical speed is passed quickly during acceleration and deceleration, then harmful vibrations are minimized, but the operational range is limited
Solution Approach 1:
The controller detects when operation near critical speed is anticipated and preemptively applies an oscillating torque component to counteract the resonant vibrations before they become harmful. This preliminary anti-action allows the system to pass through critical speed regions smoothly during acceleration and deceleration without limiting the operational range
Solution Approach 2:
The system uses feedback by continuously monitoring operating conditions and detecting critical speed ranges. Based on this feedback, the controller adjusts the torque reference in real-time to suppress vibrations, enabling the machine to operate freely across the full speed range including rapid transitions through critical speeds without harmful effects
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
The AVC effectively reduces mechanical vibrations during operation, allowing for a broader operational range by actively canceling unbalance torque and suppressing resonance frequencies, ensuring stable motor performance.
Implementation Method 1
Severe vibrations of the foundation of an electric motor occur when an electrical motor operates at natural frequencies of the mechanical body
Implementation Method 2
The oscillating incremental torque reference adds a torque component which has the purpose to cancel the unbalance torque of the electric motor, and which results from unwanted vibrations of the motor assembly
Data Source
Figure 1~2
Figure 3~4
AI summary
A method of reducing vibrations in an electric motor comprising a rotor and a stator, by means of an active vibration controller, AVC, the method comprising: a) determining whether one of an angular rotational speed of the rotor and an angular stator frequency multiplied by two is within a critical range comprising a mechanical resonance frequency of a motor assembly comprising the electric motor and its load, b) i) setting an oscillating incremental torque angular frequency of the AVC to the angular rotational speed of the rotor if the angular rotational speed of the rotor is within the critical range, or ii) setting the oscillating incremental torque angular frequency to the angular stator frequency multiplied by two if the angular stator frequency multiplied by two is within the critical range, iii) generating an oscillating incremental torque reference using the AVC with the oscillating incremental torque angular frequency set in step b i) or b ii), and iv) controlling the electric motor based on a sum of the oscillating incremental torque reference and an electrical torque reference; or c) i) deactivating the AVC if the angular rotational speed of the rotor and the angular stator frequency multiplied by two is outside the critical range, and ii) controlling the electric motor based on the electrical torque reference.