A brushless DC (BLDC) motor, also known as an electronically commutated motor, is a type of synchronous motor that operates based on the principles of a permanent magnet and electronic commutation. BLDC motors have a rotor with permanent magnets and a stator with several coils. Unlike a traditional brushed DC motor, BLDC motors use electronic commutation instead of brushes and commutator to control the power to the coils. The electronic commutation is typically done with the help of a sensor or sensorless control algorithm, which provides precise control over the motor's rotation.
A shaded pole motor is a type of single-phase induction motor. It gets its name from the shading coils or copper rings that are added to the stator poles to create a rotating magnetic field. When an alternating current is applied to the motor, the magnetic field generated by the shading coils creates a phase shift, which induces a starting torque in the motor.
The main difference between a brushless DC (BLDC) motor and a shaded pole motor lies in their construction and mode of operation.
1. Construction:
- Brushless DC Motor: A BLDC motor consists of a rotor with permanent magnets and a stator with windings. The rotor magnets are typically mounted on the motor shaft, while the stator windings are located in the motor housing.
- Shaded Pole Motor: A shaded pole motor has a cylindrical stator with a number of evenly spaced poles. Each pole has a portion called a shading coil or shading ring, which is made of a shorted turn of conducting material.
2. Operation:
- Brushless DC Motor: BLDC motors operate on the principle of electronically commutating the stator windings using a controller. The controller senses the rotor position through sensors or back electromotive force (EMF) and energizes the appropriate stator windings to generate rotational torque. As the rotor magnets pass the energized stator windings, the motor rotates.
- Shaded Pole Motor: Shaded pole motors operate on the principle of induced current in the shading coils due to a rotating magnetic field. When an AC current is applied to the stator winding, a magnetic field is created, and due to the asymmetrical placement of the shading coils, the magnetic field lags behind in certain regions. This time lag generates a secondary magnetic field in the shading coils, which creates a rotating magnetic field. The resulting interaction between the rotating magnetic field and the main magnetic field causes the rotor to rotate.
3. Performance:
- Brushless DC Motor: BLDC motors generally offer higher efficiency, better controllability, and higher torque-to-inertia ratio. They can have smoother operation, higher speeds, and better speed control compared to shaded pole motors. These motors are commonly used in applications that require precise control, such as robotics, industrial automation, and electric vehicles.
- Shaded Pole Motor: Shaded pole motors are simpler in design and less expensive compared to BLDC motors. However, they generally have lower efficiency and lower torque output. Shaded pole motors are often used in small household appliances, such as fans, refrigerators, and air conditioners.
Overall, the key distinction between a brushless DC motor and a shaded pole motor lies in the technology used for their operation, resulting in differences in construction, control, and performance characteristics.
Shaded pole motors are a type of single-phase induction motor. Unlike other types of single-phase induction motors, shaded pole motors don't use a start capacitor or a start winding to kickstart rotation. Instead, they rely on a simple design that creates a rotating magnetic field.
The rotor of a shaded pole motor is made of a solid metal cylinder or a stack of metal laminations. The rotor typically has a unique design where a portion of it is surrounded by a copper or aluminum shading coil. This coil is responsible for creating the shaded pole effect, which induces a phase shift in the magnetic field and creates the starting torque needed for the motor to begin rotating.
The materials used in the rotor of a shaded pole motor are typically low-cost metals like aluminum or steel. These materials provide the necessary magnetic properties and mechanical strength required for the motor to operate efficiently. The rotor may also be coated or treated to prevent corrosion and improve its longevity.
Overall, the rotor structure and materials of a shaded pole motor are designed to be simple, cost-effective, and reliable for applications where low starting torque and continuous operation are required, such as in small fans, appliances, and some HVAC systems.
Established in 1992, Keli motor has become one of the largest micro motor R&D, manufacturers, and exporters in China, its No. 1 sales and production of shaded pole motors. In addition to shaded pole motors, we also produce and sell stepper motor, universal motor, BLDC motor, etc.