The torque (or torque) of a motor is produced by the moment of force that interacts between the electric current and the magnetic field inside the motor. This is determined by the basic motor operating principles, which mainly include direct current motors (DC motors) and alternating current motors (AC motors).
1. Direct current motors (DC motors):
Among DC motors, there are two main types: DC motors and DC brushless motors.
DC motors: DC motors generate current by applying a DC voltage in the current path. As the current passes through the motor's coil (usually the stator), it creates a torque in the magnetic field, causing the motor to begin to rotate.
Brushless DC motors (BLDC motors): BLDC motors use a magnetic field generated by permanent magnets (usually magnets on the rotor) to interact with the current in the stator. By changing the direction and magnitude of the current at the right time, the motor can rotate.
2. Alternating current motor (AC motor):
Among AC motors, there are mainly asynchronous motors (e.g. induction motors) and synchronous motors.
Induction motor: In induction motor, there is no permanent magnet on the rotor. When an alternating current is passed through the stator, it generates a rotating magnetic field in the stator which generates the induced current in the rotor. As a result of the relative motion, a torque is generated which makes the rotor start rotating.
Synchronous Motors: Synchronous motors operate by synchronizing with an external alternating power source. The synchronization of the magnetic field between the stator and rotor allows torque to be generated, which drives the motor to rotate.
In these motors, the generation of the magnetic field and the flow of current are interrelated, and by controlling the direction and magnitude of the current, the torque of the motor can be effectively controlled. This is achieved by using devices such as motor controllers or speed controllers to ensure that the motor is able to provide the required output torque under various load conditions.
3. Stepper motor:
A stepper motor is a special type of motor whose rotation is accomplished by periodically applying current to different phases in a driver. Stepper motors rotate by a fixed angle in each stepping motion, which is often referred to as the step angle.
Electromagnetic Stepper Motors: Electromagnetic stepper motors rotate by alternating the current through an electromagnetic coil on different phases. When the current passes through the coil, the coil generates a magnetic field that interacts with the magnetic poles fixed on the rotor, thus pushing the rotor to rotate.
4. Permanent magnet stepping motor:
Permanent magnet stepper motors use permanent magnets fixed on the rotor. By changing the phase of the current, the motor can control the interaction between the permanent magnets and the coils to produce torque, which drives the motor to rotate.
The angle of rotation of a stepper motor is usually small in a single stepping action, but by accumulating multiple stepping actions, larger angles and precise position control can be achieved.
Overall, torque production in a motor is through the interaction between the current and the magnetic field, depending on the type of motor and the principle of operation. The design and control system of the motor ensures that the appropriate torque is available to meet the needs of a particular application under varying load conditions.
