Multiple factors to consider when selecting a brushless DC motor.
The brushless DC motor has a unique structure and adopts a "reverse installation" or "inside flip outside" design, which is completely different from traditional DC motors. In this structure, the armature remains stationary while the magnetic poles rotate, which is more similar to a permanent magnet synchronous motor. The armature iron core is carefully stacked from silicon steel sheets, with tooth slots arranged on the iron core to accommodate multiphase windings. Unlike the working principle of brushed DC motors, brushless DC motors require commutation operation during operation, rather than commutation. In the design stage of brushless motors, there is considerable room for choice in the number of phases, poles, slots, and arrangement and connection of the armature winding. These different choices will have a profound impact on the overall performance of the motor. Next, we will delve into several core issues that need to be considered when choosing a brushless DC motor.
1. When selecting a brushless DC motor, the primary task is to clarify the various requirements for the motor:
① Determine the power demand of the brushless DC motor, i.e. the maximum wattage.
② Clarify the speed requirements of the motor, such as the required number of revolutions per minute.
③ Specify the voltage value of the drive motor.
④ Provide the size specifications of the motor, including diameter, length, and shaft diameter dimensions.
⑤ Choose whether to equip a Hall sensor.
⑥ If a lower output speed is required, it is necessary to consider whether to pair it with a gearbox and choose the appropriate gearbox type.
2. After determining the selection parameters of the brushless DC motor, the next step is to consider the matching motor driver/controller.
The key points include:
① Ensure that the power of the selected DC brushless motor driver/controller can meet or exceed the requirements of the brushless motor.
② Evaluate the functionality of the driver/controller based on actual needs, such as the selection of speed regulation methods, which may include various methods such as analog signals.
③ If there is a communication control requirement, it is necessary to confirm whether the selected driver/controller has the corresponding functions, such as RS485 and other communication protocols.
④ Size and installation method are also important factors to consider when choosing, as the size and installation method of different drivers/controllers may vary significantly.
⑤ Regarding the digital display function, if precise display is required, it may be necessary to choose to equip it with a high-end brushless motor driver/controller.
⑥ For more complex control requirements, a distinction should be made between brushless motor drivers/controllers, which can provide more complex control functions but may also increase costs accordingly.
3. The selection of power supply is also crucial when driving and controlling DC brushless motors.
The voltage of the power supply must meet the requirements, and its power should be 30% or 50% higher than the motor power to ensure that the power supply will not overload during rapid motor movement switching. It is recommended to use a linear power supply for rectification and filtering, and increase the power margin appropriately.
