A Method of Detecting Bearing Fault Signal Based on DLIA Implemented by FPGA

Digital lock-in amplifier(DLIA) is limited by its single-frequency signal detection nature, which makes it unable to detect multi-frequency signals. In order to make DLIA suitable for multi-frequency signals and broaden the application range of DLIA, a DLIA-based multi-frequency signal detection method implemented by field programmable gate array (FPGA) is proposed. This method reconstructs multi-frequency signals by improving DLIA and combining direct digital synthesizer (DDS). First, this paper introduces the principle of signal amplitude detection of DLIA, and then analyzes the detection process of the proposed method for multi-frequency signals. Then this paper describes the application process of the proposed method on FPGA. Finally, the bearing test was carried out, and the accurate identification of the defect signal was realized. The experimental results show that the multi-frequency DLIA signal detection method has the characteristics of stable output and strong anti-interference ability. The proposed method can effectively suppress noise and reconstruct bearing fault signals.