5. FRACTIONAL HORSE POWER (FHP) MOTORS notes in english

 

5. FRACTIONAL HORSE POWER (FHP) MOTORS

Fractional Horsepower (FHP) motors are motors that operate at a power rating of less than 1 horsepower. These motors are widely used in applications requiring small amounts of power, such as small appliances, office equipment, and hobby devices. FHP motors are commonly found in consumer products like fans, pumps, and small machinery. Let’s go through the construction, working, and applications of some common types of FHP motors.

5.1 Construction, Working, and Application of the Following Motors:

5.1.1 BLDC (Brushless DC) Motor

• Construction:

  • A BLDC motor consists of a stator and a rotor, similar to traditional DC motors, but it doesn’t have brushes for commutation.
  • The stator has permanent magnets and windings, while the rotor has coils, which are energized by the controller to produce motion.
  • There are two main types of BLDC motors:
    1. Outer Rotor Type: The rotor is on the outside, and the stator is inside.
    2. Inner Rotor Type: The rotor is inside, and the stator is outside.

• Working:

  • BLDC motors are powered by a DC supply, but instead of using brushes and a commutator to reverse the current, an electronic controller is used to manage the phase changes.
  • This controller drives the current through the stator windings in a specific sequence to create a rotating magnetic field, which causes the rotor to turn.
  • Because there are no brushes to wear out, BLDC motors are more reliable, quieter, and efficient compared to brushed DC motors.

• Applications:

  • Computers (cooling fans, drives)
  • Electric Vehicles (EVs)
  • Air Conditioners
  • Small appliances like blenders, electric toothbrushes, etc.

5.1.2 Permanent Magnet Synchronous Motor (PMSM)

• Construction:

  • A Permanent Magnet Synchronous Motor consists of a stator and rotor, but unlike traditional motors, the rotor uses permanent magnets instead of windings.
  • The stator has three-phase windings, and the rotor has permanent magnets fixed to the rotor core.

• Working:

  • The rotor of a PMSM is magnetized, and when three-phase AC supply is applied to the stator, it creates a rotating magnetic field.
  • The rotor's magnetic field follows the stator’s rotating field, and the rotor synchronizes with the field, rotating at a constant speed (synchronous speed).
  • These motors operate with no slip, which makes them highly efficient, especially in applications requiring precise control.

• Applications:

  • Electric Vehicles (EVs) and Hybrid Vehicles
  • Pumps, fans, and other industrial automation applications.
  • Robotics and CNC machines (due to precise control).

5.1.3 Stepper Motor

• Construction:
  • A Stepper Motor has a rotor and stator, like other electric motors, but its rotor is divided into a number of discrete steps, which provides precision in positioning.
  • The stator has multiple coils that are energized in a particular sequence to create a rotating magnetic field.
• Working:
  • The motor divides one full rotation into a series of small, equal steps, which allows for precise control of the motor's position.
  • The rotor moves step by step as the coils in the stator are energized in a specific sequence.
  • The speed and position of the motor are controlled by controlling the sequence and timing of current to the stator coils.
• Applications:
  • Printers (for precise movement of print heads)
  • Robotics (for precise control of actuators)
  • CNC Machines (for precise movement of tools)
  • Camera Systems (for focusing and zoom control)

5.1.4 AC and DC Servomotors

• Construction:

  • Both AC and DC servomotors consist of a stator and rotor, but the difference lies in their power supply and working principle.
  • AC servomotor: This motor works on AC power supply and is used when precise control over speed and position is required. The rotor is typically a permanent magnet or an induction rotor.
  • DC servomotor: It operates using DC power supply and uses a commutator and brushes for switching the direction of current in the rotor windings to maintain rotation.

• Working:

  • AC Servomotor: In an AC servomotor, the stator generates a rotating magnetic field, and the rotor follows this field, providing the desired motion. The motor's speed and position are controlled by varying the frequency or amplitude of the AC supply.
  • DC Servomotor: A DC servomotor operates using the commutator system to reverse the current direction in the rotor, thus maintaining rotation. The motor speed is controlled by the applied voltage, and the position is controlled by feedback systems.

• Applications:

  • AC Servomotor:
    • Robotics (for precise position control)
    • CNC Machines
    • Industrial Automation (for motion control)
  • DC Servomotor:
    • Robotics
    • Automatic Doors
    • Servo mechanisms for precise control in equipment like radar antennas or camera gimbals.

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Summary of Applications:

• BLDC Motors are efficient, reliable, and used in applications such as cooling fans, electric vehicles, and small appliances.
• Permanent Magnet Synchronous Motors (PMSM) provide high efficiency and are used in applications requiring precise control, such as electric vehicles, pumps, and industrial automation.
• Stepper Motors are ideal for applications requiring precise control of position and speed, such as printers, robotics, and CNC machines.
• AC and DC Servomotors are used where precise control of speed and position is required, such as in robotics, automation, and camera systems.

FHP motors are commonly used in devices requiring small but efficient motors. Each type of FHP motor has distinct advantages and is chosen based on specific application requirements.