pmdc motor | pmdc motor working principle | construction and working | permanent magnet dc motor |dc

Summary

This lecture provides a detailed overview of Permanent Magnet DC (PMDC) motors, explaining their operation, construction, and applications. It covers how PMDC motors use permanent magnets to generate a magnetic field, converting electrical energy to mechanical energy. The lecture also highlights the simplicity of PMDC motor construction, the role of the armature, and the torque generation process. Additionally, it discusses the advantages of PMDC motors, such as reduced size and cost, and their widespread use in applications like toys, automobiles, and household devices. The presentation also introduces different types of DC motors and their specific uses.

Takeaways

• 😀 PMDC motors use permanent magnets to generate the required magnetic field for operation.
• 😀 The basic construction of a PMDC motor is simple, with permanent magnets arranged in an alternating North and South pole configuration.
• 😀 The stator of a PMDC motor is typically made of laminated steel, with the inner poles of the permanent magnets placed within it.
• 😀 The rotor, also known as the armature, is made of laminated steel and has windings placed on it, similar to conventional DC motors.
• 😀 In PMDC motors, no external field excitation is needed, which reduces the overall size of the motor.
• 😀 The torque in a PMDC motor is generated when current-carrying conductors placed in the magnetic field experience an electromagnetic force in a tangential direction.
• 😀 The direction of rotation in a PMDC motor is determined using Fleming’s left-hand rule.
• 😀 One advantage of PMDC motors is that they do not require field excitation arrangements, making them cheaper and more economical for small-rated applications.
• 😀 PMDC motors are commonly used in small appliances like toy cars, wipers, blowers, and computer disk drives.
• 😀 PMDC motors are more suitable for applications where a small-sized DC motor is required, as in toys, automotive systems, and small home appliances.
• 😀 Different types of DC motors are available, including PMDC, separately excited, self-excited, and differential compound motors, each suited for specific applications.

Q & A

What is a Permanent Magnet DC (PMDC) motor?

A Permanent Magnet DC (PMDC) motor is a type of DC motor that uses permanent magnets to produce the necessary magnetic field for operation, instead of relying on an external field excitation system.

What are the advantages of using PMDC motors?

PMDC motors are economical, compact, and have a simpler construction due to the absence of a field coil. This reduces their overall size and cost, making them ideal for smaller applications.

How does the construction of a PMDC motor differ from conventional DC motors?

The main difference is that PMDC motors use permanent magnets to generate the magnetic field, whereas conventional DC motors require a field coil for the same purpose. The rotor and armature in both types are similar, being made of laminated steel with windings.

How does the rotor in a PMDC motor operate?

The rotor (or armature) in a PMDC motor rotates due to the electromagnetic force acting on it when current flows through the windings, which are placed within the magnetic field produced by the permanent magnets.

What role do the commutator and brushes play in a PMDC motor?

The commutator and brushes supply electrical current to the armature windings. They ensure that the current direction in the windings changes as the armature rotates, which helps in maintaining continuous rotation.

What is the significance of Fleming's Left-Hand Rule in the operation of PMDC motors?

Fleming's Left-Hand Rule helps determine the direction of force, current, and magnetic field in a motor. It is used to predict the direction of rotation of the armature in PMDC motors when current flows through the windings.

What are some common applications of PMDC motors?

PMDC motors are widely used in applications like battery-operated toys, automobile starters, windshield wipers, vacuum cleaners, computer disk drives, fans, drills, and conveyors.

Why are PMDC motors considered more compact than other types of motors?

PMDC motors are more compact because they do not require field coils, which reduces the overall size of the motor. The permanent magnets provide the necessary magnetic field, eliminating the need for additional components.

What is back EMF in a PMDC motor?

Back EMF (Electromotive Force) is the voltage generated in the armature windings when the motor is running. It is induced as the stationary magnetic flux is cut by the rotating armature, and it opposes the applied voltage, reducing the current flowing through the motor.

What are the different types of DC motors mentioned in the script?

The script mentions several types of DC motors, including Permanent Magnet DC Motors, Separately Excited DC Motors, Self-Excited DC Motors, and Compound DC Motors. Each type has its specific applications depending on the requirements.