Drone Motors

INTRODUCTION

An electric motor is particularly designed for use in unmanned aerial vehicles (UAV) or in drones. Drone motor is an essential part of drones that is responsible for powering the drones and making it more capable to fly in the air, so that these drones can be used in various fields like agriculture, photography and army uses.

HISTORY OF DRONE MOTORS

The history of drone motors dates back to the early 1900’s when the first electric motor was invented. However, it wasn’t invented until the 1960’s when the first modern drone was developed, and with this invention, new needs emerged like the drone motor should be powerful and lightweight.

                         The first drone motors were the brushed DC motors; these motors were simple, cheap and easily available. But they tended to wear out quickly and were inefficient. In the 1990’s, brushless DC motors were introduced, these motors were relatively efficient than their brushed counterparts. Brushless DC motors use electronic commutation instead of brushes that reduces friction. 

                  When the lithium-ion batteries were introduced in 2000’s , drone motors became more efficient and powerful because lithium-ion batteries have a higher energy density than previous battery technologies, allowing drones to fly for much longer duration of time. Thus, we can say that with the advancement in battery technology and the need for light weighted and powerful motors, drone motors also started got advance.

 DIFFERENCE BETWEEN BRUSHED AND BRUSHLESS DRONE MOTORS

Drone motors can be generally categorised into two different types:-

1. BRUSHED DC MOTORS.        

2. BRUSHLESS DC MOTORS.  

The majority of FPV drones use brushless DC motors because they are relatively efficient, durable and more powerful. However brushed drone motors are also used in some micro and nano drones due to its low cost.

                                  Both brushed and brushless have same working function as they both work on the principle of electromagnetism but they differ from their construction.

CONSTRUCTION OF BRUSHED DRONE MOTOR

A brushed motor consists of several key components, including a rotor , stator, brushes, and a commutator. The rotor is the rotating part of the motor, which contains the permanent magnets. The stator is the stationary part, which contains the coil of wire. The brushes are made up of conductive material and are used to transfer electricity to the commutator, which is a segmented metal ring that switches the direction of the electric current in the coils. When electricity flows through the coil in the stator, a magnetic field is produced this interacts with the magnets on the rotor that causes it to spin. These brushes transfer the electricity to the commutator, which switches the direction of the current as the rotor starts spinning. This ensures that the magnetic fields in the stator continue to interact with the magnets on the rotor which keeps it rotating.

                                     These motors are relatively simple and inexpensive but these are less efficient and have a shorter lifespan. But these motors are still used in nano motors and other types.

CONSTRUCTION OF BRUSHLESS DC MOTOR  

 

          A brushless DC motor consists of several key components, including a stator,                              a rotor, electric speed controller (ESC) and several Hall Effect sensors, the stator is the stationary part of motor and contains the coils of wire, while the rotor is the rotating part and contains the permanent magnets. The ESC plays an essential role in brushless DC motor as it controls the speed and direction of the motor and the Hall Effect sensors provide feedback to the ESC.  

Brushless DC motor uses electronic controls to switch the direction of the current in the coils. The ESC receives signals from the drone’s flight controller and uses these signals to control the flow of electricity to the coils, creating a rotating magnetic field that interacts with the permanent magnets on the rotor which causes it to rotate. 

                                        The Hall Effect sensors allow ESC to adjust the timing and strength of the current to the coils, which in turns affects the speed and the torque of the motor. This allows for much greater precision. Brushless motors are more efficient and have a longer life span than brushed motors, making them suitable for high performance drones, however they are more expensive to produce and require more sophisticated electronic controls.  

MOTORING SIZE 

The size of drone motor is usually expressed in two measurements:

• Diameter and Height 

The diameter refers to the distance across the motor’s circular body, while the height refers to the distance from the bottom of the motor to the top of the bell that houses the magnets.

Drone motors are available in a range of sizes, typically measured in millimetres. Common sizes range from 10mm to 60 mm in diameter with heights ranging from 3mm to 4mm.This size depends upon the requirement for the particular drone depending upon its size, weight and power requirement. 

                                      Large drone motors are generally more powerful and suitable for larger, heavier drones that require more lift. Its important to choose the right size motor for your drone to ensure that it has the necessary power to lift off and fly smoothly, without being too heavy or too weak.

MOTOR SPECIFICATIONS

A drone motor’s specifications are very important while selecting a motor for your drone 

KV Rating:  It indicates the motor’s rpm per volt that affects the speed and performance of the drone.

The voltage and current draw:  It indicates the amount of power the motor consumes and the need of battery.

The power and thrust: It indicates the amount of force that the motor can produce, that affects the drone’s lifting capabilities.

Efficiency: It indicates how much power is converted into mechanical output, which gives us the idea of overall performance and flight time of the drone.

Propeller: The propeller also plays a critical role in determining the flight characteristics of the drone. The size and pitch of the propeller can affect the amount of thrust generated and the speed at which the drone can fly. The material and shape of the propeller can also impact the efficiency and noise level of the drone 

After discussing all the basic points regarding drone motor, it is necessary to choose the best drone motor according to your requirement. Choosing the best drone motor requires consideration of several factors such as size, weight, desired flight characteristics and also the type of the propulsion system being used .Here are the steps taken while choosing your required drone motor.

Determine the size and weight of the drone: The size and weight of the drone will determine the size and power requirements of the motor. Generally, the larger and heavier the drone, the larger and more powerful the motor needs to be.

Determine the desired flight characteristics: The flight characteristics of the drone will determine the type of motor you need. For example, if you want a fast and agile drone, you will need a motor with a high power-to-weight ratio. If you want a drone that can hover and take stable footage, you will need a motor with a low KV (RPM per volt) rating.

Consider the type of propulsion system: There are two types of propulsion systems used in drones: brushed and brushless. Brushed motors are cheaper and simpler, but they are less efficient and have a shorter lifespan. Brushless motors are more expensive, but they are more efficient and have a longer lifespan.

Look for motors with a high power-to-weight ratio: The power-to-weight ratio is the amount of power the motor can produce per unit of weight. Look for motors with a high power-to-weight ratio, as these will provide better performance and longer flight times.

Consider the KV rating: The KV rating is the RPM per volt of the motor. A motor with a low KV rating will produce more torque and is better for applications that require low RPM, such as aerial photography. A motor with a high KV rating will produce higher RPM and is better for applications that require speed, such as racing.

Check the motor's efficiency: The efficiency of the motor is important because it will determine the flight time of the drone. Look for motors with a high efficiency rating, as these will provide longer flight times.

Consider the quality and brand of the motor: The quality and brand of the motor are important because they will determine the lifespan and reliability of the motor. Look for motors from reputable brands that have a proven track record of reliability and quality.

FUTURE DEVELOPMENT

The field of drone motor technology is rapidly evolving and new developments in motor technology are also on the horizon; example, the science can use better materials which can lead to more efficient and lightweight motors, while innovation in motor control could improve the precision and stability of drone flight.

CONCLUSION 

In conclusion, understanding the fundamentals of drone motors is crucial for anyone interested in building or flying drones. Choosing the right motor for your drone can greatly impact its performance, efficiency, and overall flight experience. Key factors to consider when selecting a drone motor include its size, weight, KV rating, and power output. It's also important to match your motor selection with the appropriate propellers and ESCs to ensure optimal performance. With the right knowledge and careful consideration, you can choose a drone motor that meets your specific needs and helps you achieve the flight experience you desire.