自动控制理论10课件

1、自动控制理论10自动控制理论10Topics of this classWhat is called Bode diagrams?Elemental Bode diagrams.Bode diagrams of compound transfer functions (Reading Module 15)Sample problemsTopics of this classWhat is ca1. Bode diagrams of simple transfer functionWe begin the study by means of the following open-loop tra

2、nsfer function Suppose its Bode diagram is required. It is known from previous, The bode diagrams consistes of two parts.the magnitudethe phase1. Bode diagrams of simple traone: Magnitude part In the magnitude part of the bode diagrams, The x-coordinate is the frequency v , but it is graduated by lg

3、 v .And the Y-coordinate is modulus M, but the modulus is expressed in decibels, Mdb .one: Magnitude part In the two: Phase part In the phase part of the bode diagrams, The x-coordinate is the frequency v , but it is graduated by lg v .And the Y-coordinate is phase angle . Plotted on a logarithmic s

4、calePlotted on a horizontal scaletwo: Phase part In the phas2. Elemental Bode diagramsIn this section, the bode diagrams of some classic elements will be talked aboutGain elementThe integral elementFirst-order lag elementThe inverse of the first-order lag elementThe second-order lag elementThe inver

5、se of the second-order lag element2. Elemental Bode diagramsIn tAccurate magnitude of the second-order lag element with the damping ratio changingAccurate magnitude of the seco3. Bode diagrams of compound transfer functionIn this section, we will talk about how to determine the bode diagrams of comp

6、ound transfer function by using the classic elementsSuppose we wish to draw the Bode diagram of the open-loop transfer function The transfer function consists of four separate transfer functions(classic elements ) 3. Bode diagrams of compound tPlot Mdb against v Adding the component plots for magnit

7、ude.Plot Mdb against v Adding thePlot f against v Adding the component plots for phase.Plot f against v Adding the coThe basic method for drawing Bode diagramsThe bode diagram for the compound transfer function is obtained by adding the component plots for both magnitude and phase.The basic method f

8、or drawing BExamples 1: An open-loop system has a transfer function of the form , draw the Bode diagrams Solution:There are three separate elements.Two break frequencyThe slope of the low-frequency is zero.The phase-frequency isExamples 1: An open-loop systeExamples 2: An open-loop system has a tran

9、sfer function of the form , draw the Bode diagrams Solution:There are three separate elements.Two break frequencyThe slope of the low-frequency is -40db/dec.The phase-frequency is Examples 2: An open-loop systeThere are three separate elements.Two break frequencyThe slope of the low-frequency is -40db/dec.The phase-frequency is Examples 3