Research on Drawing Curve of Magnitude-Phase Frequency Characteristic Based on Open-Loop

The method of frequency analysis to linear-system is a very important method in classical automation theory,and the Nyqusit criterion is key in learning and teaching.Drawing the curve of magnitude-phase frequency characteristic based on open-loop is foundation of using Nyqusit criterion.In order to improve the students' understanding about its concept,this article emphasizes principles of drawing curve about general linear-system magnitude-phase frequency characteristic on open-loop,then analyzes magnitude and phase of curve's primal and terminal.Some examples indicate that this method is simple and convenient;furthermore it gets a good teaching effect.