DC Motor Model


Published on

DC Motor Model and
Advantages and Disadvantages of AC and DC Machine

Published in: Education, Business

DC Motor Model

  1. 1. UNIVERSITY OF ENGINEERING & TECHNOLOGY< ABBOTTABAD CAMPUS Electrical Machine Title: DC Motor Model and Advantages and Disadvantages of AC and DC Machine Zunaib Ali
  2. 2. Design Motor Task Division Section 1 (Motor Model) Section 2 (Advantages and Disadvantages of DC and AC Machine) 1. Muhammad Hafiz Saifullah b. Satia 1. Ian Jasper 2. Muhd Izwan Ikhmal 2. Farah Aqilah bt Md Nasir 3. Shahrul Haziq Bin M. 4. Muhd Nur Farhan Bin Hamdan Jamil 3. Siti Norfika bt Khamis 4. Muhammad Salleh Hassanuddin b. Sanusi 5. Shafiqrullah Bin Samsuddin. 6. Ali Syariati b. Abd Wahab
  3. 3. Design Motor Our DC Motor Background •Design is based on the construction of brush DC Motor. • There are permanent magnets on the outside and a spinning armature on the inside •When electricity is put into this electromagnet, it creates a magnetic field in the armature that attracts and repels the magnets in the stator. •The armature will spin.
  4. 4. Design Motor Material Used and Cost TYPE OF MATERIAL COST 1 Wood Block Free 2 Recycle Bottle Free 3 Wire Winding RM 5.00 4 Card Board RM 7.50 5 Permanent Magnet RM 6.00 (ceramic) 6 Car battery (sponsored) Free 7 Soldering Flux Free TOTAL COST RM18.50
  6. 6. Design Motor
  7. 7. Introduction DC Motor  DC motor is an electric motor that runs on direct current (DC) electricity.  Two types of DC motor - brush and brushless DC Motor.  Brushed DC electric motor generates torque directly from DC power supplied to the motor by using internal commutation, stationary magnets (permanent or electromagnets), and rotating electrical magnets.  Brushless DC motors use a rotating permanent magnet or soft magnetic core in the rotor, and stationary electrical magnets on the motor housing.
  8. 8. Introduction AC Motor  AC motor is an electric motor driven by an alternating current.  Commonly consists of two basic parts, an outside stationary stator having coils supplied with alternating current to produce a rotating magnetic field, and an inside rotor attached to the output shaft that is given a torque by the rotating field.  Two main types of AC motors- depending on the type of rotor used. - the asynchronous motor - the synchronous motor
  9. 9. Operation of DC Motor
  10. 10. Operation of DC Motor 1. When the coil is powered, a magnetic field is generated around the armature. The left side of the armature is pushed away from the left magnet and drawn toward the right, causing rotation. 2. The armature continues to rotate. 3. When the armature becomes horizontally aligned, the commutator reverses the direction of current through the coil, reversing the magnetic field. 4. The process then repeats.
  11. 11. Advantages of DC Motor Overall advantages that will be discussed are; 1. Provide excellent speed control for acceleration and deceleration. 2. Easy to understand design 3. Simple, cheap drive design
  12. 12. Advantages of DC Motor  Provide excellent speed control - power supply of a DC motor connects directly to the field of the motor allows for precise voltage control, which is necessary with speed and torque control applications. (DC shunt motor) - The higher the armature voltage, the faster the rotation. This relationship is linear to the motor's maximum speed. (DC series motor)
  13. 13. Advantages of DC Motor  Easy to understand design - The design of the brushed DC motor is quite simple. A permanent magnetic field is created in the stator by either of two means:   Permanent magnets Electro-magnetic windings - If the field is created by permanent magnets, the motor is said to be a "permanent magnet DC motor" (PMDC). - If created by electromagnetic windings, the motor is often said to be a "shunt wound DC motor" (SWDC).
  14. 14. Advantages of DC Motor  Simple and cheap drive design -Varying the speed of a brushed DC motor requires little more than a large enough potentiometer. -In practice, these have been replaced for all but sub-fractional horsepower applications by the SCR (Silicon Controlled Rectifiers) and PWM (Pulse Width Modulation) drives, which offer relatively precisely control voltage and current. - Adding an SCR allows simple voltage variability simply by turning the knob and thereby the speed of the motor. -Pulse-width modulation is an effective method for adjusting the amount of power delivered to an electrical load
  15. 15. Disadvantages of DC Motor  High maintenance - care required to maintain the mechanical interface used to get current to the rotating field. - maintenance includes the commutator (the collection of copper and mica segments attached to the rotor winding over which the brushes pass), and the brushes themselves.  Not suitable in very clean environment. - vulnerable to dust which decreases performance.
  16. 16. Operation of AC Motor  AC motor has two basic electrical parts: a "stator" and a "rotor“. Rotor Stator
  17. 17. Operation of AC Motor  Principle of operation for all AC motors relies on the interaction of a revolving magnetic field created in the stator by AC current, with an opposing magnetic field either induced on the rotor or provided by a separate DC current so urce.  Resulting interaction produces usable torque, which can be coupled to desired loads throughout the facility in a convenient manner.
  18. 18. Advantages of AC Motor     Low cost Speed variation High power factor Reliable operation
  19. 19. Advantages of AC Motor  Low Cost - Lowest cost motor for applications requiring more than about 1/2 hp (325 watts). - due to the simple design of the motor. - For this reason, AC motors are preferred for fixed speed applications in industrial applications and for commercial and domestic applications where AC line power can be easily attached. - Over 90% of all motors are AC induction motors. - Can be found in air conditioners, washers, dryers, industrial machinery, fans, blowers, vacuum cleaners and many other.
  20. 20. Advantages of AC Motor  Speed variation - The fixed number of winding sets (known as poles) built into the ac motor, which determines the ac motor's base speed. - The frequency of the AC line voltage. Variable speed drives (Adjustable speed drives) change this frequency to change the speed of the motor. - The amount of torque loading on the motor, which causes slip.
  21. 21. Advantages of AC Motor  High power factor - power factor of an AC electrical power system is defined as the ratio of the real power flowing to the load to the apparent power in the circuit. - a load with a low power factor draws more current than a load with a high power factor for the same amount of useful power transferred. - higher currents increase the energy lost in the distribution system, and require larger wires and other equipment.
  22. 22. Advantages of AC Motor Reliable Operation -The simple design of the AC motor results in extremely reliable, low maintenance operation. -Unlike the DC motor, there are no brushes to replace. -If run in the appropriate environment for its enclosure, the AC motor can expect to need new bearings after several years of operation. If the application is well designed, an AC motor may not need new bearings for more than a decade.
  23. 23. Disadvantages of AC Motor  Inability to operate at low speeds - We know that standard AC motors should not be operated at speeds less than about 1/3 of base speed. This is due to thermal considerations. In fact a DC motor should be considered for these applications.  Poor positioning control - Positioning control is expensive and crude with AC motors too. Even a vector drive is very crude when controlling the standard AC motor. - Servo DC motors are more appropriate for these applications.
  24. 24. Disadvantages of AC Motor  AC will produce eddy currents due to the production of a back emf. - Because motors are generators that operate in reverse, they produce an emf just like generators do. - Called as back emf and does not immediately appear when a motor is initially turned on. - The back emf is a consequence of Lenz's law, which states that an induced emf produces a magnetic flux that resists the change. - Back emf works to reduce the current in the loop, thus slowing the motor down, and it gets larger as the speed of the motor increases.
  25. 25. Conclusion  The advantages and disadvantages of DC and AC motor somehow depends on application used. • The reference of DC and AC refers how the electrical current is transferred through and from the motor. Both the types of the motors have different functions and applications. • However, AC motor is widely used in industry application that support AC source voltage.