Question

choose a type of electric motor and search the internet to find the specs and operational information such as horsepower rating available cost and common application

Answer 1

Electric motors may be classified by considerations such as power source type, internal construction, application and type of motion output. In addition to AC versus DC types, motors may be brushed or brushless, may be of various phase like single-phase, two-phase, or three-phase, and may be either air-cooled or liquid-cooled. In this i choose DC motor and it has specifications like,

A DC motor's general specifications usually include weight, shaft length and shaft diameter as well as motor length and diameter. Other useful dimensions include the location of mounting holes and thread type. If only the length or diameter are provided, refer to an image, photo or scale drawing to get a sense of the other dimensions based on the one known value.

1. "Torque" is calculated by multiplying a force (acting at a distance away from a pivot) by the distance. A motor rated at a stall torque of 10Nm can hold 10N at the end of 1m. Similarly, it could also hold 20N at the end of 0.5m (20 x 0.50 = 10)

Note: 1 Kg * force of gravity (9.81m/s2) = 9.81N (~10N)

2. Nominal voltage

3. No load RPM

4. Power Rating

5. Stall Torque

6. Stall current

Operational information:

Electric motors run by electromagnetism. However, there are also other types of motors that utilize electrostatic forces or piezoelectric effect. In the case of a PMDC {Permanent Magnet DC) motor, motion is produced by an electromagnet (armature) interacting with a fixed field magnet (housing assembly).

In a brushed motor, electrical current flows through the motor terminals in the endcap assembly that comes in contact with the commutator in the armature assembly through the carbon brushes or brush leaves. The electrical current powers the coils generating a magnetic field causing the armature to rotate as it interacts with the magnets encased in the housing assembly. Flemming’s Left Hand Rule helps to determine the direction of the force, the current and the magnetic flux.

In a brushless motor, when electricity is applied across the motor termination, a current flows through a fixed stator field and is interacting with a moving permanent magnet or a moving induced magnetic field inside a rotor / armature. After the motion and force load have been met by the available source current it returns back to the source exiting the motor.

Key Elements Interacting to Produce Motion

Magnetic Flux - A motor can have a fixed wound coil or a permanent magnet stator and a moving wound coil armature or PM rotor that will have interacting magnetic flux fields to produce a force and motion.

Force - The amount of current that flows through the electromagnetic field is proportional to the amount of interacting electromagnetic field force required to achieve the opposing work load. In addition to the force and motion needed by the device one must consider any efficiency loss in the conversion of electrical power into mechanical work (watts).

Most electric motors are designed to run at 50% to 100% of rated load. Maximum efficiency is usually near 75% of rated load. Thus, a 10-horsepower (hp) motor has an acceptable load range of 5 to 10 hp; peak efficiency is at 7.5 hp. A motor’s efficiency tends to decrease dramatically below about 50% load.

Applications:

Electric bike applications

Hub motor used in electric bike application and its a direct wheel motor without any transmission losses

Electric car application

The motor used in electric car application is fitted with transmission to get the power from battery and controlled by power electronic controller. Mechanical energy from the motor will be transmitted from motor via transmission to the car wheels. The motor can be fitted in front side or back side of the vehicle.

Drones applications

Drones need four motors and controlled by controller for its lift and balanced fly.