An electric motor (English: Electric machinery, commonly known as a "motor") is an electromagnetic device that converts or transmits electrical energy based on the law of electromagnetic induction.
In circuits, an electric motor is represented by the letter M (D in the old standard). Its main function is to generate driving torque and serve as a power source for electrical appliances or various machines. A generator is represented by the letter G in circuits. Its main function is to convert mechanical energy into electrical energy.
1. According to the type of power supply: motors can be divided into DC motors and AC motors.
1) DC motors can be classified into brushless DC motors and brushed DC motors according to their structure and working principle.
2) AC motors can be further divided into single-phase motors and three-phase motors.
2. According to structure and working principle, motors can be divided into DC motors, asynchronous motors, and synchronous motors.
1) Synchronous motors can be classified as: permanent magnet synchronous motors, reluctance synchronous motors, and hysteresis synchronous motors.
2) Asynchronous motors can be divided into: induction motors and AC commutator motors.
3. According to the starting and running methods, single-phase asynchronous motors can be divided into: capacitor-start single-phase asynchronous motors, capacitor-run single-phase asynchronous motors, capacitor-start-run single-phase asynchronous motors, and split-phase single-phase asynchronous motors.
4. According to their purpose, electric motors can be divided into drive motors and control motors.
1) Drive motors can be divided into: power tools (including tools for drilling, polishing, grinding, grooving, cutting, reaming, etc.)
Electric motors and household appliances (including washing machines, electric fans, refrigerators, air conditioners, tape recorders, video recorders, DVD players, vacuum cleaners, cameras, hair dryers, electric shavers, etc.)
Electric motors are used in electric motors and other general-purpose small mechanical equipment (including various small machine tools, small machinery, medical devices, electronic instruments, etc.).
2) Control motors are further divided into stepper motors and servo motors, etc.
5. According to the rotor structure, induction motors can be divided into: squirrel-cage induction motors (formerly known as squirrel-cage asynchronous motors) and wound-rotor induction motors (formerly known as wound-rotor asynchronous motors).
6. According to operating speed, motors can be classified as: high-speed motors, low-speed motors, constant-speed motors, and variable-speed motors. Low-speed motors are further divided into geared motors, electromagnetic geared motors, torque motors, and claw-pole synchronous motors, etc.
The working principle of a DC generator is to convert the alternating electromotive force induced in the armature coil into a direct current electromotive force when it is drawn out from the brush terminals by the commutation action of the commutator and the brushes.
The direction of the induced electromotive force is determined by the right-hand rule (the magnetic field lines point to the palm, the thumb points to the direction of the conductor's motion, and the other four fingers point to the direction of the induced electromotive force in the conductor).
The direction of the force on a conductor is determined by the left-hand rule. This pair of electromagnetic forces creates a torque acting on the armature, which is called electromagnetic torque in a rotating electrical machine. The direction of the torque is counterclockwise, attempting to make the armature rotate counterclockwise. If this electromagnetic torque can overcome the resistive torque on the armature (such as the resistive torque caused by friction and other load torques), the armature can rotate counterclockwise.
DC motors are electric motors that operate on DC working voltage and are widely used in radios, video recorders, DVD players, electric shavers, hair dryers, electronic watches, toys, etc.
When the power supply line is not very long, the relationship between power and wire diameter (national standard copper wire)
