Essay On Servo Motor

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2.1 INTRODUCTION 2.2 MATHEMATICAL MODELING OF DC SERVO CONTROL Dc servo motor is widely used for industrial and domestic purpose. it is necessary to establish the mathematical model of DC servo motor here we are using armature control DC motor to control speed and position of Dc motor. In armature control of DC motor the resistance Ra and inductance La connected in series and voltage is representing the back emf of DC servo motor. The motor parameter and variable define as follow. Consider armature control dc motor shown in fig 2.2.1ARMATURE CONTROL DC-SERVO MOTOR Ra= resistance of armature (ohm). La= inductance (H) = armature current (A). = field current (A). = armature voltage (V). = back emf (volts). = torque of motor (Nm). θ = angular displacement of motor (rad). = equivalent moment of inertia of motor (kg-m2). = viscous friction coefficient In servo application, the dc motor is generally used in the linear range of the magnetization curve. Therefore, the air gap flux is proportional of the field current, i.e. ………………(i) Where is the constant. The torque developed by the motor is proportional to the product of the armature of the current and air gap flux i.e. ………(ii) Where is the constant. In the armature-controlled dc motor, the field armature is kept constant, so the equation can be written as ………(iii) Where is motor torque constant. The motor back emfis proportional to speed is given as ……...(iv) Where is the back emf constant. The differential of the armature circuit is ………..(v) The torque equation is given as …………..(vi) Taking Laplace transform of equ... ... middle of paper ... ...tion of the process model. we can also add the integrator to the process model. Moreover , we can give all the poles as real and under-damped (complex pole) from the above case the process model is best fit in third order model P3U in figure 2.8. In figure 2.8 we can see that the output of process model exactly follow the input of the process model. Figure2.6 Transient response of the model Figure2.7 Estimation of process model Figure 2.8 Simulated and measured output model of dc-servo motor The open loop transfer function of the dc-servo motor where as angular velocity is the output and voltage as input given below. 2.5 CHAPTER SUMMRARY This chapter gives mathematical modeling of dc-servo motor and a detail of model estimation of system identification toolbox.

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