Electric Machine Resonance Control Through Magnetic Stiffness Modulation
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Solution Overview
Problem
Rotating machinery, such as aircraft propulsion systems, face challenges in controlling vibrations at critical speeds due to resonance, which can cause damage and require heavy damping systems that are prone to failure and limit operational ranges.
Innovation Solution
A method involving an electric machine with a rotor and stator that senses resonance conditions and adjusts the magnetic field to modulate the stiffness of the rotating machinery, using integral control to shift the resonance away from critical speeds, allowing operation across a wider range of speeds while reducing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If damping systems are used to reduce vibrations at critical speeds, then vibration levels are reduced, but the system weight increases and reliability decreases
Solution Approach 1:
The patent replaces mechanical damping systems with an electromagnetic control system. The electric machine's magnetic field is dynamically adjusted to counteract resonant vibrations, substituting passive mechanical dampers with an active electromagnetic control mechanism that reduces vibrations without the weight and reliability issues of traditional damping systems
Solution Approach 2:
The patent changes the operating parameters of the electric machine by dynamically adjusting the magnetic field strength and stiffness characteristics. By modulating the magnetic field parameters in response to detected resonance conditions, the system actively counteracts vibrations at critical speeds without requiring additional mechanical damping components
2Object-affected harmful factors
If damping systems are used to reduce vibrations, then vibration levels are reduced, but the device complexity and weight increase
Solution Approach 1:
The patent makes the electric machine multi-functional by enabling it to perform both its primary propulsion/generation function and a secondary vibration control function. The same electric machine uses its magnetic field to both drive the rotor and actively counteract resonant vibrations, eliminating the need for separate damping system weight
Solution Approach 2:
The patent replaces heavy mechanical damping systems with a lightweight electromagnetic control system that uses the existing electric machine's magnetic field. This substitution dramatically reduces the weight required for vibration control while maintaining effectiveness
3Reliability
If keep-out zones are implemented to avoid critical speeds, then component damage is prevented, but the operational range and productivity are reduced
Solution Approach 1:
The patent makes the system's stiffness characteristics dynamic rather than fixed. By continuously adjusting the magnetic field and stiffness parameters in real-time, the system can safely operate through critical speeds that would traditionally require avoidances, expanding the operational range while maintaining component protection
Solution Approach 2:
The patent implements a feedback control system that detects resonance conditions and automatically adjusts the magnetic field to counteract vibrations. This closed-loop control allows the system to safely operate at speeds that would previously require keep-out zones, eliminating operational restrictions while protecting components
4Object-affected harmful factors
If the magnetic field is adjusted to modulate stiffness and move resonance conditions, then vibration at critical speeds is reduced, but the control system complexity increases
Solution Approach 1:
The patent enables the electric machine to self-regulate its magnetic field characteristics in response to detected resonance conditions. The system uses its own control infrastructure to automatically adjust stiffness and counteract vibrations without requiring external complex control systems
Solution Approach 2:
The patent merges the vibration control function with the existing electric machine control system. By integrating the resonance mitigation capabilities into the existing motor/generator control infrastructure, the patent avoids adding separate complex control systems while achieving active vibration management
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 enables operation at a broader range of speeds without excessive vibration, reducing the need for 'keep-out zones and extending the life of components by actively managing resonance conditions through controlled stiffness adjustments.
Implementation Method 1
adjusting a magnetic field of one or both of the rotor and the stator to provide a predetermined torque to the rotating machine, to modulate the stiffness of the rotational machinery
Implementation Method 2
an electric machine with a rotor and stator that senses resonance conditions and adjusts the magnetic field
Implementation Method 3
Vibrations are particularly pronounced at particular rotational speeds / frequencies, known as 'critical' speeds, in view of resonances of the rotating system
Data Source
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AI summary
A method of control of an electric machine (18), and an electric machine control system. The electric machine coupled to rotating machinery (12) and comprises a rotor (22) and a stator (24). The method comprises sensing one or more parameters indicative of one or more resonance conditions of the rotating machinery (12), and comparing the sensed parameter to a predetermined threshold to determine whether the rotating machinery (12) is operating at the resonance condition. Where the rotating machinery (12) is determined to be operating at the resonance condition, adjusting a magnetic field of one or both of the rotor (22) and the stator (24) to provide a predetermined torque to the rotating machine (18), to modulate the stiffness of the rotational machinery (12), and thereby move the resonance condition away from the current rotating machinery conditions.