Motor Dc Model

Motor Dc Model. 2 The basic equations of the DC motor 6 constitutes a model of the DC motor which may 6 be represented as a nonlinear dynamic system The main restrictions of.

Physical SetupSystem EquationsDesign RequirementsMATLAB RepresentationA common actuator in control systems is the DC motor It directly provides rotary motion and coupled with wheels or drums and cables can provide translational motion The electric equivalent circuit of the armature and the freebody diagram of the rotor are shown in the following figure For this example we will assume that the input of the system is the voltage source () applied to the motor&#39s armature while the output is the rotational speed of the shaft The rotor and shaft are assumed to be rigid We further assume a viscous friction model that is the friction torque is proportional to shaft angular velocity The physical parameters for our example are In general the torque generated by a DC motor is proportional to the armature current and the strength of the magnetic field In this example we will assume that the magnetic field is constant and therefore that the motor torque is proportional to only the armature current by a constant factor as shown in the equation below This is referred to as an armaturecontrolled motor (1) The back emf is proportional to the angular velocity of the shaft by a constant factor (2) In SI units the motor torque and back emf constants are equal that is therefore we will use to represent both the motor torque constant and the back emf constant From the figure above we can derive the following governing equations based on Newton&#39s 2nd law and Kirchhoff&#39s voltage law (3) (4) 1 Transfer Function Applying the Laplace transform the above modeling equations can be expressed in terms of the Laplace variable s (5) (6) We arrive at the following openloop transfer function by eliminatin First consider that our uncompensated motor rotates at 01 rad/sec in steady state for an input voltage of 1 Volt (this is demonstrated in the DC Motor Speed System Analysispage where the system&#39s openloop response is simulated) Since the most basic requirement of a motor is that it should rotate at the desired speed we will require that the steadystate error of the motor speed be less than 1% Another performance requirement for our motor is that it must accelerate to its steadystate speed as soon as it turns on In this case we want it to have a settling time less than 2 seconds Also since a speed faster than the reference may damage the equipment we want to have a step response with overshoot of less than 5% In summary for a unit step command in motor speed the control system&#39s output should meet the following requirements 1 Transfer Function We can represent the above openloop transfer function of the motor in MATLAB by defining the parameters and transfer function as follows Running this code in the command window produces the output shown below 2 State Space We can also represent the system using the statespace equations The following additional MATLAB commands create a statespace model of the motor and produce the output shown below when run in the MATLAB command window The above statespace model can also be generated by converting your existing transfer function model into statespace form This is again accomplished with the sscommand as shown below Published with MATLAB® 92.

DC Motor Definition, Working Principle, Types, Uses, FAQs

DC Motor Model In this example you model a DC motor driven by a constant input signal that approximates a pulsewidth modulated signal and look at the current and rotational motion at the motor output To see the completed model open the PWMControlled DC Motor example Select Blocks to Represent System Components.

DC motor model with electrical and torque characteristics and

The commutator of a DC motor is a cylindrical structure that is made of copper segments stacked together but insulated from each other using mica The primary function of a commutator is to supply electrical current to the armature winding Brushes The brushes of a DC motor are made with graphite and carbon structure.