科学计算科学计算 (52).pdf

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1、9.29.2 Creation and Mask of SubsystemCreation and Mask of SubsystemThe creation of subsystemsThe mask of subsystemsThe conditional execute of subsystems1 1The The C Creation of reation of S SubsystemsubsystemsCreate a subsystem through the subsystem blocksConvert the existing blocks into a subsystem

2、The difference between the two is that the former creates a subsystem first and then adds function blocks;the latter selects blocks first and then creates the subsystem.Lets take the creation of y=kx+b subsystem as an example.(1)Create a subsystem through the subsystem blocksDouble-click the subsyst

3、em block to open the subsystem editing window.In the window,An interconnected input block and an output block have been added automatically.They respectively represent the input port and the output port of the subsystem.Insert the block to be grouped between the input block and the output block.Two

4、constant blocks,k and b,are needed here.A product block and an SUM block.Group these blocks and a subsystem is created.Check the Scope curve after starting the simulation.The blue curve is a sine curve.The yellow curve is y=kx+b.Here,in the Command Window,assign 3 to k and 2 to b.That is to say,the

5、yellow curve represents y=3sint+2 (2)Convert the existing blocks into a subsystemThe system model created is shown in the figure.Select all the blocks in the system model,then select related commands in the Diagram menu in the Simulink Editor.Or press Ctrl+G to create a subsystem.The selected blocks

6、 will be replaced by a subsystem block.If you want to view the internal structure of the subsystem,you can double-click the subsystem block.2 2The The MMask of ask of S SubsystemubsystemSelect the subsystem to be masked,then in the Simulation Editor select Create Mask command in Diagram MenuItem,or

7、press Ctrl+M key combination.The Mask Editor dialog box will appear.The first tabbed pane is used to create blockmask icons.The second tabbed pane is used to designmask dialog boxes.The third tabbed pane is used to set theinitialization command.The fourth tabbed pane is used to define thetype,descri

8、ption and help text for of theblock mask.This tabbed pane consists of 3 parts On the left is the Controls.The middle area shows the dialog controls in the dialog box.The right area is used to display and modify properties of controls.Next,lets take y=kx+b subsystem as an example to illustrate the me

9、thod of setting Parameters&Dialog.On the left control toolbar of the second tabbed pane,double-click the Edit button to prepare input positions for the 2 variables of the subsystem.Enter the Prompt and Name of the control in the middle area,and finally click the OK button to confirm the settings.Aft

10、er setting the subsystem Parameters&dialog,double-click the subsystem icon to display its parameters dialog box.For example,double-click the icon of subsystem y=kx+b in the simulation model,the parameters dialog box as shown in the figure will pop up,which allows users to enter values for the parame

11、ters k and b.Asubsystem controlled by the control signal is called the conditionally executed subsystem.In the conditionally executed subsystem,the output signal depends on the input signal and the control signal.The conditionally executed subsystem:Enabled subsystemTriggered subsystemEnabled&trigge

12、red subsystem3 3T The he C Conditional onditional E Execute of xecute of S Subsystemsubsystems(1)Create a subsystem through the subsystem blocksEnabled subsystem indicates when the control signal changes from negative to positive,the subsystem starts to execute until the control signal becomes negat

13、ive again.The control signal can be a scalar or a vector.If the control signal is a scalar,then when the value of the scalar is greater than 0,the subsystem starts to execute.If the control signal is a vector,then when any element in the vector is greater than 0 the subsystem will execute.The enable

14、d subsystem has an Enable control signal input port.Enable means if and only if the Enable input signal is positive,the block receives the input signal.The enabled subsystem block can be directly selected to create the enabled subsystem.Double-click the enabled subsystem block to open its internal s

15、tructure window.You can also expand the existing subsystems to add ports and enabled blocks in the subsystem model library,and convert the subsystem to an enabled subsystem.Example 1:Create a sine half-wave rectifier using the enabled subsystem.Create a new simulation model,drag three blocks of Sine

16、 Wave,Enabled Subsystem and Scope to the newly opened Simulation Editor.Connect each block,set parameters and save on the disk.Create an enabled subsystem where the Enabled Subsystem is terminated with the Sine Wave block.For comparison,in addition to the display of half-wave rectifying waveform,it

17、also shows the sine wave.So set the number of input ports to 2 in the Scope window,and set the output layout.Click the Run command button on the toolbar in the Simulink Editor,you can see the half-wave rectified waveform and the sine waveform.Here the Sine Wave is the control signal.When the control

18、 signal is negative,the subsystem stops executing and the output is zero.(2)Triggered subsystemTriggered subsystem refers to when a trigger event occurs the subsystem starts to execute.Similar to the enabled subsystem,the triggered subsystem can be created by directly selecting the triggered subsyst

19、em blocks,or expand an existing subsystem to add Trigger blocks in the Ports&Subsystem model library,and convert this subsystem to a triggered subsystem.Rising:When the control signal rises from anegative value or 0 to a positive value,thesubsystem starts to execute.Falling:When the control signal d

20、rops from apositive value or 0 to a negative value thesubsystem starts to execute.Either:When the control signal meets the triggercondition of either rising or falling,thesubsystem starts to execute.Function-call:which indicates that the trigger ofthe subsystem is determined by the internal logicof the S-function.Example 2:Using the triggered subsystem.(3)Enabled&triggered subsystemThe so-called enabled&triggered subsystem,means that when the enable control signal interacts with the trigger control signal,the subsystem start to execute.