What are the advantages and disadvantages of brushless DC motors.
Brushless motors include the motor body and drive, and are typical electromechanical integrated products.
Advantages of brushless DC motor:
1. It has excellent linear mechanical characteristics of DC motors, a wide speed range, and can achieve stepless speed regulation with a wide speed range;
2. Excellent torque characteristics, good torque performance at medium and low speeds, large starting torque, and small starting current; Strong overload capacity;
3. Soft start and soft stop, with good braking characteristics, can eliminate the need for existing mechanical or electromagnetic braking devices;
4. High efficiency, brushless DC motors have no excitation loss compared to AC motors, and no brush friction loss or spark compared to brushed DC motors;
5. High reliability, good stability, strong adaptability, and simple maintenance;
6. Small size, light weight, and high output;
7. Resistant to bumps and vibrations, low noise, minimal vibration, smooth operation, and long lifespan.
Disadvantages of brushless DC motors:
1. Cost: Rare earth permanent magnets are much more expensive than other permanent magnets, which leads to an increase in the cost of electric motors.
2. Limited constant power range: A large constant power range is crucial for achieving high vehicle efficiency. A permanent magnet brushless DC motor cannot achieve a maximum speed greater than twice the base speed.
3. Safety: In the process of motor manufacturing, large rare earth permanent magnets may pose a danger as they can attract scattered metal objects. In case of a vehicle accident, if the wheels spin freely while the electric motor is still excited by permanent magnets, high voltage will appear at the motor terminals, which may endanger passengers or rescuers.
4. Magnetic demagnetization: Permanent magnets can be demagnetized by large reverse magnetic forces and high temperatures. The critical demagnetization force varies for each type of permanent magnet material. When cooling an electric motor, especially if the motor structure is compact, great care must be taken.
5. High speed performance: Electric motors with surface mounted permanent magnets cannot achieve high speeds due to limitations in the mechanical strength of the assembly between the rotor yoke and the permanent magnets.
