直流电机simulink.docx

直流电机simulink DC MachineImplement separately excited DC machine (continuous and discrete blocks)Library Machines DescriptionThe DC Machine block and the Discrete DC Machine block (also in the Machines library) both implement a separately excited DC machine. The DC Machine block implements a continuous model, and the Discrete DC Machine block implements a discrete model. The following description applies to both blocks.An access is provided to the field terminals (F+, F-) so that the machine model can be used as a shunt-connected or a series-connected DC machine. The torque applied to the shaft is provided at the Simulink input TL.The armature circuit (A+, A-) consists of an inductor La and resistor Ra in series with a counter-electromotive force (CEMF) E.The CEMF is proportional to the machine speed. E=Ke*w.KE is the voltage constant and ω is the machine speed.In a separately excited DC machine model, the voltage constant KE is proportional to the field current If: Ke=Laf*Ifwhere Laf is the field-armature mutual inductance.The electromechanical torque developed by the DC machine is proportional to the armature current Ia. Te=Kt*Ia.where KT is the torque constant. The sign convention for Te and TL is The torque constant is equal to the voltage constant. The armature circuit is connected between the A+ and A- ports of the DC Machine block. It is represented by a series Ra La branch in series witha Controlled Voltage Source and a Current Measurement block. Mechanical part: The field circuit is represented by an RL circuit. It is connected between the F+ and F- ports of the DC Machine block.The mechanical part computes the speed of the DC machine from the net torque applied to the rotor. The speed is used to implement the CEMF voltage E of the armature circuit.The mechanical part is represented by Simulink blocks that implement the equation where J=inertia,Bm=viscous friction coefficient,and Tf=Coulomb friction torque.Dialog Box and Parameters Preset ModelProvides a set of predetermined electrical and mechanical parameters for various DC machine ratings of power (HP), DC voltage (V), rated speed (rpm), and field voltage (V).Select one of the preset models to load the corresponding electrical and mechanical parameters in the entries of the dialog box. Select No if you don't want to use a preset model.Select Show detailed parameters toview and edit the detailed parameters associated with the preset model.Mechanical inputAllows you to select either the torque applied to the shaft or the rotorspeed as the Simulink signal applied to the block's input.Select Torque Tm to specify a torqueinput, in N.m or in pu, and change labeling of the block's input to Tm.The machine speed is determined by the machine Inertia J (or inertia constant H for the pu machine) and by the difference between the applied mechanical torque Tm and the internal electromagnetic torque Te. The sign convention for the mechanical torque is the following: when the speed is positive, a positive torque signal indicates motor mode and a negative signal indicates generator mode.Select Speed w to specify a speed input,in rad/s or in pu, and change labeling of the block's input to w.The machine speed is imposed and the mechanical part of the model (Inertia J) is ignored. Using the speed as the mechanical input allows modeling a mechanical coupling between two machines and interfacing with SimMechanics and SimDriveline.The next figure indicates how to model a stiff shaft interconnection in a motor-generator. The speed output of machine 1 (motor) is connected to the speed input of machine 2 (generator), while machine 2 electromagnetic torque output Te is applied to the mechanical torque input Tm of machine 1.The Kw factor takes into account speed units of both machines (pu or rad/s)and gear box ratio. The KT factor takes into account torque units of bothmachines (pu or N.m) and machine ratings. Also, as the inertia J2 is ignored in machine 2, J2 referred to machine 1 speed must be added to machine 1 inertia J1. Show detailed parametersIf selected, the mask displays the detailed parameters of the DC Machine block. The detailed parameters can be modified no matter the preset model you selected in the Preset Model list. Armature resistance and inductance [Ra La]The armature resistance Ra, in ohms, and the armature inductance La, in henries.Field resistance and inductance [Rf Lf]The field resistance Rf, in ohms, and the field inductance Lf, in henries.Field armature mutual inductance Laf The field armature mutual inductance, in henries.Total inertia JThe total inertia of the DC machine, in kg.m2.Viscous friction coefficient BmThe total friction coefficient of the DC machine, in N.m.s.Coulomb friction torque TfThe total Coulomb friction torque constant of the DC machine, in N.m. Initial speedSpecifies an initial speed for the DC machine, in rad/s,。