Ⅰ. The core role of drone motors
As the 'power heart' of a drone, the motor converts electrical energy into mechanical energy to drive the propellers, generating lift/thrust, which directly affects the drone's payload, endurance, stability, and flight speed.
Ⅱ. Common Types of Motors and Their Differences
1. Classification by structure (core classification)
- Brushless motors (mainstream): No carbon brush wear, high efficiency (60%-90%), long lifespan (several thousand hours), low noise, require the use of an electronic speed controller (ESC), suitable for multi-rotors and medium to large fixed-wing aircraft, higher cost.
- Brushed motors: contain carbon brushes for commutation, with a simple structure and low cost, low efficiency (30%-60%), short lifespan (a few hundred hours), and high noise, only used in micro drones (such as toy-grade).
2. Classified by Use
- Dedicated to multirotors: focuses on low speed and high torque, suitable for large-diameter propellers;
- Fixed-wing / racing drones: Focused on high RPM and low torque, suitable for small-diameter propellers.
Ⅲ. Core Working Principles
- Brushless motorThe ESC receives signals from the flight controller and controls the three-phase coils to be energized in sequence, generating a rotating magnetic field that drives the permanent magnet rotor to rotate (no mechanical commutation is required, relying on electronic signals to switch the current direction).
- Brushed motorBy contacting the carbon brushes with the commutator, the coil current direction is automatically switched, allowing the rotor to continue rotating (mechanical commutation is prone to wear and has limited efficiency).
Ⅳ. Key Steps in Purchase Selection
1. Check the KV value (core parameter)
- Definition: For every 1V increase in voltage, the motor's no-load speed increases by a certain value (for example, KV1000 = 1000 RPM per 1V).
- Matching: High KV (>1500) with small propellers (e.g., 5-7 inches) is suitable for racing drones (high speed); low KV (<1000) with large propellers (e.g., 10-20 inches) is suitable for heavy-lift / aerial photography drones (high torque).
2. Check power and voltage
- Power (W) = Voltage (V, e.g., 48V lithium battery) × Current (A). The motor needs to match the drone's payload (the larger the payload, the higher the motor power required).
- The voltage needs to be compatible with the battery and ESC (for example, a 12S battery → 50.4V, choose a 50.4V compatible motor).
3. Match size and weight
- Dimensions: shaft diameter (e.g., 3mm/5mm, must match the propeller hole diameter), mounting hole distance (corresponding to the fixed position on the frame);
- Weight: Prioritize lightweight design (to reduce overall machine load), but power must be balanced (to avoid 'a small horse pulling a big cart').
4. Consider the brand and cooling performance
- Choose a reputable brand to avoid poor-quality motors stalling or overheating.
- For high-power scenarios (such as loaders), motors with heat sinks are preferred.
Ⅴ. Conclusion
The selection of a drone motor is a 'demand-matching' process — first clarify the flight scenario (such as aerial photography or racing), focus on the three core aspects: KV value, power, and compatibility, and then consider brand reliability. This way, you can choose a suitable 'power heart' to lay a solid foundation for the stable operation of the drone.