How to choose UAV motor

Motor function

The motor can turn the propeller of the drone to generate power. The power of multi-rotor drones comes from propellers.

Types and differences of motors

Generally, motors are divided into brush motors and brushless motors. For multi-rotor UAVs, small UAVs usually use brushed motors, such as coreless motors; while UAVs with a large wheelbase, usually greater than 200mm, use brushless motors. Current UAVs are mostly based on permanent magnet synchronous motors among brushless motors.

Why are motors divided into brushed and brushless?

Brushed motor uses carbon brushes to change the direction of current, while a brushless motor abandons the carbon brushes and uses electronic commutation to reduce losses.

Service life

Brushless motor: It can work continuously for about 20,000 hours, and the conventional service life is 7-10 years. Brushed motor: It can work continuously for about 5000 hours, and the normal service life is 2-3 years.
Note: The working time is related to the use environment (mainly temperature). The higher the temperature, the lower the efficiency. Therefore, pay attention to ensuring that the motor temperature is within a benign range, which can greatly increase the service life and effect of the motor.

Energy saving

In contrast, the power consumption of brushless motors is only 1/3 of that of brush motors. In terms of daily maintenance  Brushed motors are much more expensive than brushless motors. The most important thing is that the overall function will be affected.

The brushless motor lacks the brush, and the wear is mainly on the bearing. From a mechanical point of view, the brushless motor is almost a maintenance-free motor. When necessary, only need to do some dust removal maintenance.

Basic parameters of the motor

Maximum current (A), maximum voltage (V), KV value.

KV value: refers to the speed of the motor under unit voltage. Generally, the higher the KV value, the faster the motor speed.  For example: the KV value is 1000, which means: the motor rotates at 1000 revolutions per minute at a voltage of 1V. Under a voltage of 10V, the motor speed is: 10V*1000KV=10000 rpm. Therefore, if you want to increase the speed of the motor, a motor with a low KV value can be achieved by increasing the voltage, but when considering the motor, it must be considered Voltage limit.

Motor naming

Four digits, the first two digits are the diameter of the stator, and the last two digits are the height of the stator. Such as 2303specification motor, the diameter of the stator is 23mm, the height is 3mm.

How to choose a motor

The sum of the maximum pulling force of the motors of the multi-rotor should not be less than 1.5 times the total weight, preferably twice upward. When selecting a motor, pay attention to the KV number of the motor and the corresponding battery voltage and propeller size. Reliable merchants generally provide a motor parameter table, which includes the recommended propellers and the pulling force and current under the corresponding conditions. According to these parameters, the corresponding electronic governor and propeller can be selected.

How to maintain the motor

If the drone tilts for no reason or fails to land smoothly when hovering, there may be a problem with the motor. You can try to recalibrate the fuselage before taking off. If the problem still occurs, you must send it to the factory for maintenance in time to avoid the occurrence of motor stalls causing the drone to lose control or even crash.  In addition, confirm that the motor is fixed to the propeller before flying, and check and clean the motor in time after flying.