BENTLY 125840-01

Description

BENTLY 125840-01

BENTLY 125840-01

The vibration pickup of this system adopts a piezoelectric ceramic vibration sensor, whose output is a weak signal that will be mixed with interference noise. Therefore, the basic configuration of the sensor control system is shown in Figure 2. The output signal must be filtered, amplified, and preprocessed. The principle of the signal conditioning circuit is shown in Figure 3.
(1) Design of Charge Amplifier: The input stage of this conditioning circuit uses a high input impedance operational amplifier to form a charge amplifier, with a feedback capacitor Cf of 1000 μ F. Take 1 as the isolated coupling capacitor Cg μ F. The smaller capacitance value is used to reduce the leakage current of the capacitor and improve the stability of the system. In addition, the charges generated by piezoelectric ceramic vibration sensors will fluctuate at low frequencies with environmental changes. Therefore, the output stage of this charge amplifier incorporates a first-order RC high pass filter circuit, with a cutoff frequency of 1Hz, which has a significant attenuation of low-frequency noise below 0.9Hz. CH takes 100 μ F. Take 100k Ω for RH. (2) The design of a fourth order Butterworth low-pass filter should not only suppress low-frequency level fluctuation noise, but also have a high-performance low-pass filter to block various high-frequency noise in the output signal of piezoelectric ceramic sensors. Therefore, the conditioning circuit adds a fourth order Butterworth low-pass filter composed of two second-order low-pass filters connected in series after charge amplification. According to the range set for crankshaft dynamic balance testing (i.e. the highest frequency of the fundamental wave), the cut-off frequency of this filter is taken as fc=13Hz. The parameters of the filter include cutoff frequency fc and damping ratio ζ And gain Av. The relationship between these three is given by the normalized Butterworth polynomial Bn (s), where n is the order:
According to the increment Av=1+Rf/Ri and fc=1/(2 π RC) of the in-phase amplifier, the circuit parameters of R, C, Rf1, Ri1, Rf2, Ri2, etc. of the first and second stages can be obtained. The fourth order low-pass filter has a high attenuation rate for high-frequency noise within the passband, with a 10 octave frequency range of -80dB, ensuring the authenticity and stability of the signal. 3. System Software Design 3.1 Methods and Principles Used in Software Design

MHD093B-058-NG1-BN
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MHD093C-058-PP0-BN
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MHD093B-058-PG1-AN
MHD093B-058-NG0-BN
MHD093C-058-NG0-BN
MHD093C-058-NG1-BN
MHD093C-035-NP0-BN
MHD093B-035-NG0-AN
MHD093C-035-NP0-AN
MHD093C-058-PP1-BN
MHD093C-035-PG0-BN
MHD093B-035-PP1-BN
MHD093C-058-NG0-AN
MHD093B-035-NP0-BN
MHD093C-035-NP1-BN