Frequency Response Measurement Using Multi-Sine and Sweep Switching
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Solution Overview
Problem
Conventional frequency characteristic measurement methods for motor systems are time-consuming due to the need for gradual frequency sweeps, and existing solutions either suffer from low resolution in varying frequency regions or face aliasing issues when sampling frequencies are insufficient.
Innovation Solution
A frequency characteristic measurement device that generates multi-sine signals and sweep sinusoidal waves with adjustable phases, allowing for high-resolution measurements by switching between multi-sine and sweep signals based on the Nyquist frequency, enabling efficient data acquisition and accurate frequency characteristic calculation across different frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sinusoidal sweep measurement is performed by gradually increasing the frequency in the measurement band, then the frequency characteristic can be measured with sufficient resolution, but the measurement time becomes excessively long
Solution Approach 1:
The measurement band is divided into multiple frequency regions based on the Nyquist frequency. The patent segments the frequency range into a first frequency region (0 to Nyquist frequency) and a second frequency region (Nyquist frequency to upper limit frequency), allowing different measurement strategies to be applied to each segment, thereby reducing overall measurement time while maintaining accuracy in critical regions
Solution Approach 2:
The patent dynamically switches between multi-sine wave measurement and sinusoidal sweep measurement based on the frequency region. In the first frequency region where the sampling frequency is sufficient, multi-sine wave measurement is used for rapid measurement. In the second frequency region where aliasing occurs, sinusoidal sweep measurement is applied to ensure measurement accuracy, creating a dynamic adaptive measurement system
2Loss of time
If a multi-sine wave is used for fast Fourier transform measurement, then the measurement time is reduced, but aliasing occurs when the sampling frequency is insufficient for high frequency signals
Solution Approach 1:
The patent applies different measurement methods to different frequency regions based on local sampling conditions. In the first frequency region where the sampling frequency satisfies the Nyquist criterion, multi-sine wave measurement is applied for fast measurement. In the second frequency region where aliasing would occur, sinusoidal sweep measurement is used instead, ensuring local measurement quality matches local sampling capabilities
3Measurement precision
If the measurement is performed with high resolution in regions with large transfer function variation, then measurement accuracy is improved, but the overall measurement time increases
Solution Approach 1:
The patent changes the measurement parameter (measurement method) based on the frequency region characteristics. By identifying regions with large transfer function variation and applying sinusoidal sweep measurement with finer frequency steps in those regions, while using faster multi-sine wave measurement in regions with smaller variations, the patent optimizes the balance between measurement accuracy and measurement time
Data Source
AI summary
A frequency characteristic measurement device that measures the frequency characteristic of a measurement target includes: a multi-sine signal generation unit that generates a multi-sine signal; a sweep sinusoidal wave generation unit that generates a plurality of sweep sinusoidal waves; an input signal switching unit that selects any one of the multi-sine signal and the sweep sinusoidal waves so as to input the selected one to the measurement target; a data acquisition unit that acquires, at a predetermined sampling frequency, sampling data of an input signal which is input to the measurement target and sampling data of an output signal which is output from the measurement target; and a characteristic calculation unit that calculates a frequency characteristic including the gain and the phase of the input and output signals in the measurement target from the sampling data of the input and output acquired.