Brushless Motor Resonance Control via Oscillation Frequency Correction
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Solution Overview
Problem
Brushless polyphase electric motors experience resonance and noise due to harmonic distortions and load fluctuations, which existing motor control techniques fail to fully mitigate, leading to torque ripples and vibrations.
Innovation Solution
A motor control apparatus and method that includes a voltage applying means, rotational speed sensing, oscillation frequency obtaining, and correcting means to identify and reduce resonance frequencies by adjusting the voltage applied to the windings, thereby minimizing resonance and noise in the motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If voltage is applied to windings based on sine waveform induced voltage, then motor operation is smooth, but resonance and noise occur at specific frequencies due to harmonic distortions and load fluctuations
Solution Approach 1:
The patent applies vibration analysis to detect resonance frequencies in the motor system. By sensing oscillation frequencies and comparing them with predetermined resonance frequencies, the system identifies when mechanical vibrations are occurring. The correction then adjusts voltage application to reduce these vibrations, directly addressing the resonance and noise problem while maintaining smooth motor operation.
2Stability of the object's composition
If existing motor control techniques are used to reduce torque ripple and cogging, then some oscillations are reduced, but resonance at specific frequencies still occurs due to harmonic components and load fluctuations
Solution Approach 1:
The patent implements a feedback mechanism where oscillation frequencies are continuously sensed and compared with predetermined resonance frequencies. When resonance is detected, the system provides feedback by correcting the voltage application to the windings. This closed-loop feedback approach dynamically adjusts the control to eliminate resonance at specific frequencies while maintaining the benefits of existing torque ripple reduction techniques.
3Object-affected harmful factors
If voltage is corrected to reduce resonance, then noise and vibrations are minimized, but additional control complexity is introduced
Solution Approach 1:
The patent applies preliminary action by pre-storing multiple sets of correction values corresponding to different oscillation frequencies in a lookup table. Instead of performing complex real-time calculations, the system simply senses the oscillation frequency and retrieves the appropriate correction value from memory. This approach minimizes noise and vibrations while avoiding the complexity of real-time resonance correction calculations.
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 solution effectively reduces resonance and noise in brushless polyphase electric motors by correcting voltage application based on sensed oscillation frequencies, improving motor stability and performance by minimizing torque ripples and vibrations.
Implementation Method 1
the voltage is sequentially applied to windings of multiple phases on a phase-by-phase basis (i.e., applying the voltage to the windings of one phase and then applying the voltage to the windings of a next phase, and so on) to sequentially flow the current through the windings of the multiple phases and thereby to generate a rotating magnetic field
Implementation Method 2
a rotational speed sensing means for sensing a rotational speed of the rotor, which is rotated by a rotating magnetic field
Data Source
AI summary
In a polyphase electric motor, a voltage is sequentially applied to a plurality of windings on a phase-by-phase basis. Then, there is sensed a rotational speed of a rotor, which is rotated by a rotating magnetic field that is generated by sequentially flowing an electric current in the windings on the phase-by-phase basis upon the sequential application of the voltage to the windings. Then, an oscillation frequency of a periodic oscillation, which is generated in the motor at the sensed rotational speed of the rotor, is obtained. Thereafter, it is determined whether the obtained oscillation frequency is a predetermined resonance frequency. Next, the voltage to be applied to the windings is corrected in a manner that reduces a resonance generated in the motor when a result of the determination indicates that the obtained oscillation frequency is the predetermined resonance frequency.