Power frequency interference and suppression measures in single chip microcomputer temperature control system

2013-09-19
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Power frequency harmonic interference is the most common interference component in microcomputer detection and control systems. In order to eliminate this interference, this paper has made a relatively detailed theoretical derivation and proposed that in the temperature detection and control system, analog RC filtering and n-fold sampling digital mean filtering synchronized with the power grid voltage signal are combined to form a detection and control system that strongly suppresses power frequency interference. And good results have been achieved in the actual temperature detection and control system. Keywords: Power frequency synchronous sampling high-order harmonics When developing and analyzing the temperature measuring instrument, although an active filter circuit was adopted, the displayed temperature value was still unstable. According to the analysis of the A/D conversion circuit, the unstable voltage of the detection signal is between 0 and 0.5mv, and the interference signal mainly comes from the power frequency interference of the power grid. In the process of power supply rectification, a large number of high-order harmonic signals are generated, and these interference signals are the main factors causing unstable display. To suppress and eliminate power frequency interference, we adopted a dual-integral A/D converter with a sampling frequency that is an integer (even) multiple of the power frequency (50Hz), which effectively solved the problem of power frequency interference.

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Power frequency interference and suppression measures in single chip microcomputer temperature control system

Document Introduction