document.getElementById("af-footer-1405154631").className = "af-footer af-quirksMode"; Armature Voltage Control of DC Motor. @*/false; With armature control the voltage is varied using several methods. This in turn reduces the motor speed in proportion to the voltage that’s being applied. Speed control can be achieved using DC drives in a number of ways. The current in the rheostat produces a voltage drop which subtracts from the fixed source voltage E s, yielding a smaller supply voltage across the armature. The armature voltage control of D.C. motor provides (a) constant torque drive (b) constant voltage drive (c) constant current drive (d) none of the above At t= 0.5 sec., the armature voltage is suddenly reversed and the motor runs in the negative direction. The stator consists of field windings while the rotor (also called the armature) consists of an armature winding. Like most of the electrical machines, DC motor has two parts namely electrical and mechanical and These methods are referred to as “armature control” and “field control.”. In the armature control method, the speed of the DC motor is directly proportional to the back emf (Eb) and Eb = V- IaRa. Armature control is the most common control technique for DC motors. The motor field current I fm is kept constant so that the motor field flux ϕ m also remains constant. For example a DC car at a stop can generate lots of torque because 100 volts will produce 2000 rpm of slip. As an open loop system, the field control method is ideal for operators who need cost-effectiveness, smooth performance and steady output. Field Controlled DC Series Motor The speed equation of a DC motor shows that, N α E b / φ or N α (V – I a R a)/ φ But the resistance of armature winding is small. Also See: Ward Leonard Method of Speed Control of DC motor or Armature Voltage Control. You can also contact us online using our form. 15-2, the ac power is rectified to produce dc power for the field wmding. Is The Speed . The reduction in field current reduces the amount of flux and as a result the speed of the motor increases. It is helpful for search any topics. Since they are connected in parallel, the armature … Armature Control for DC Motors. When the value of variable resistance Re is increased, the motor runs at a lower speed. Closed loop systems are often the preferred choice for operators and business leaders who are looking for stability and the convenience of an automated process. The speed of a series DC motor can also be controlled using either armature voltage control or armature circuit resistance. In armature voltage control method the speed control is achieved by varying the applied voltage in the armature winding of the motor. Question: Question 2 Given The Block Diagram (20 Marks) DC MOTOR ARMATURE CONTROL DC MOTOR SPEED CONTROL Open Loop Block Diagram Disturbance Input Td(s) Td(s) Input TLS) Output W(s) 2s+0.5 Transfer Function 1/(Js+b) Scope Va(s) Ta() Tm(s) 10 1/Ra Km Кь 0.1- 1. Speed Control of D.C. Shunt Motor (Part3) 3. document.getElementById("af-header-1405154631").className = "af-header af-quirksMode"; One of the most important features of the dc motor is that their speed can easily be control according to the requirement by using simple methods. Field controlled DC motors are more common for longer processes due to their reliability and convenience. Additional advantages of armature controlled DC motors include: While armature controlled motors are fast and ideal for short, fixed processes, they have a few disadvantages to consider when comparing armature control vs. field control: When using the field control method for DC motors, the field is weakened to increase the speed or it can be strengthened to reduce the motor’s speed. This speed control method is also known as Ward Leonard Method, which is discussed in detail under the topic Ward Leonard Method or Armature Voltage Control. With armature control the voltage is varied using several methods. Since the variable resistance carries full armature current, it must be designed to carry continuously the full armature current. the armature voltage has a control over the torque developed in the armature. if (document.getElementById("af-footer-1405154631")) { Provided the motor excitation is kept constant, the DC drive power factor is proportional to motor speed. On the other hand, there are certain cases when a different motor control method may be more effective. The armature voltage control of D.C. motor provides a) Constant torque drive b) Constant voltage drive c) Constant current drive d) None of the above Voltage Control of Speed Control of DC Series Motor In this method of speed control by inserting rheostat with the series field, we can control the armature voltage and thereby speed of the motor. Such type of control is impossible in an AC motor. The speed–current characteristic of a series motor is shown in the figure below. In Fig. A coil is placed in a magnetic field, and when an electric current passes through the coil, a torque is produced, causing the motor to turn. A large amount of power is wasted in the external resistance Re. There are three general methods of speed control of a DC Motor. over 90% of our motors are customized. The following are the advantages of the field flux control method. A DC motor consists of two parts: a rotor and a stator. A separate variable voltage source is required in this method. ET 438a Automatic Control Systems Technology 1 LEARNING OBJECTIVES 2 x After this presentation you will be able to: Write the transfer function for an armature controlled dc motor.