AC Motor Control Apparatus Resonance Suppression via Voltage Vector Amplitude Limiting
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Solution Overview
Problem
Existing control apparatuses for AC motors do not effectively suppress noise and vibration caused by resonance in the AC motor drive system, particularly when the specific frequency of the inverter bus current's amplitude spectrum matches the resonance frequency of the circuit components.
Innovation Solution
A control apparatus that includes an inverter, a voltage command calculation unit, a voltage waveform specifying unit, an amplitude spectrum extraction unit, and a voltage amplitude limiting unit, which calculates and limits the voltage vector's amplitude to prevent the amplitude spectrum of specific frequencies from exceeding a determination threshold, thereby reducing noise and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the inverter operates at high power output, then the productivity and performance of the AC motor drive system is improved, but noise and vibration increase due to resonance when specific frequency matches resonance frequency
Solution Approach 1:
The control apparatus continuously monitors the amplitude spectrum of bus current and compares it with the determination threshold. When the amplitude at resonance frequency exceeds the threshold, the system automatically limits the voltage vector amplitude to suppress resonance. This closed-loop feedback mechanism enables dynamic adjustment of voltage output to maintain high performance while preventing noise and vibration.
Solution Approach 2:
The system dynamically changes the voltage vector amplitude parameter based on real-time spectral analysis. When resonance is detected, the voltage amplitude is reduced to push the operating point away from resonance conditions. This parameter adjustment allows the system to operate at high power levels normally while preventing resonance-induced noise and vibration when conditions align.
2Object-affected harmful factors
If the voltage vector amplitude is limited to suppress resonance, then noise and vibration are reduced, but the motor output performance may be compromised
Solution Approach 1:
The voltage amplitude limitation is not static but dynamically adjusted based on real-time spectral analysis. The system only applies amplitude limitation when the amplitude spectrum exceeds the determination threshold, and maintains full power output when resonance conditions are not present. This dynamic approach ensures noise and vibration are suppressed only when necessary, preserving motor output performance during normal operation.
3Object-affected harmful factors
If real-time spectral analysis is performed to detect resonance, then noise and vibration suppression becomes effective, but device complexity increases
Solution Approach 1:
The system replaces complex mechanical resonance suppression methods with electrical control and signal processing. By using spectral analysis of bus current and voltage vector control, the system achieves resonance suppression through software-based detection and control, avoiding the need for additional mechanical dampers or complex hardware modifications.
Data Source
AI summary
A control apparatus for an AC motor includes an inverter, a voltage-command calculation unit calculating a vector used for giving a command to the inverter, a voltage-waveform specifying unit specifying, as a voltage waveform for operating the inverter based on the vector, a pulse pattern selected from previously stored voltage waveforms, or a voltage waveform of a PWM signal generated by a comparison between a phase voltage and a carrier wave, an amplitude-spectrum extraction unit obtaining a bus current of the inverter to extract an amplitude spectrum of a specific frequency corresponding to a resonance frequency of a circuit through which the bus current flows, and a voltage-amplitude limiting unit limiting an amplitude of the vector so that the amplitude spectrum of the specific frequency becomes less than a threshold, if the amplitude spectrum of the specific frequency correlating with the voltage waveform is the threshold or more.