Down-conversion and signal-conversion integrated system

Abstract

The invention relates to a transformer partial discharging signal acquisition device, in particular to a down-conversion and signal-conversion integrated system, which solves the technical problems of large interference and poor reliability of a detected result because the existing partial discharging signal processed by the analogue down-conversion is required to be transmitted to an analogue-digital (AD) sampling card through a coaxial cable. The down-conversion and signal-conversion integrated system comprises a printed circuit board (PCB) and a field programmable gate array (FPGA) chip, and is characterized in that: the PCB consists of a plurality of cloth boards and is integrated with a down-conversion module; the down-conversion module comprises a filter amplifying circuit and two frequency mixing branches connected with the filter amplifying circuit; the filter amplifying circuit is composed of an amplifier and a filter, one end of which is connected with a signal interface for accessing a signal; and each of the frequency mixing branches comprises a multiplier and a low-pass filter. The down-conversion and signal-conversion integrated system realizes integration of the down-conversion and the AD sampling card on one PCB card, so the transmission by the coaxial cable is eliminated, the signal loss is low, the interference is reduced, and the frequency and spectrum mixing caused by frequency mixing by one branch is eliminated.

Description

technical field [0001] The invention relates to a device for collecting partial discharge signals of transformers, in particular to an integrated system for down-conversion and signal conversion. Background technique [0002] At present, the known transformer partial discharge signal acquisition system consists of discrete analog down-conversion and AD sampling cards. The analog down-conversion is responsible for moving the partial discharge signal from the high-frequency band to the low-frequency band, and the AD sampling card is responsible for digitizing the signal after spectrum shifting. The analog down-conversion is composed of a local oscillator and a multiplier. The local oscillator is responsible for generating local oscillator signals of different frequencies, and the multiplier completes the multiplication of the partial discharge signal and the local oscillator signal. After the partial discharge signal enters the analog down-conversion, the local oscillator als...

AI Technical Summary

Problems solved by technology

The signal passes through the connector -> coaxial cable -> connector, which is inconvenient to install, and has a large insertion loss and is easy to introduce interference

The most serious problem is that the analog down-conversion will cause spectrum aliasing when mixing. For example, we want to sample an 800M signal, and then we set the local oscillator signal to 790M, so that the frequency of the 800M signal becomes 10M after mixing, but The signal frequency of 780M will also change to 10M. The 10M signal sampled by the AD sampling card is actually the superposition of the two frequency band signals before mixing, which reduces the reliability of the detection results.

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