The operating principle of the rotating machine

Update:04-01-2019
Summary:

The operating principle of the rotating machine is base […]

The operating principle of the rotating machine is based on the law of electromagnetic induction and the law of electromagnetic force. When the motor performs energy conversion, it should have two major components that can move relative to each other: the component that establishes the excitation magnetic field, and the inductive component that induces the electromotive force and flows through the working current. Of these two components, the stationary one is called the stator, and the rotating motion is called the rotor. There is an air gap between the stator and the rotor for the rotor to rotate.

The electromagnetic torque is generated by the interaction of the excitation magnetic field in the air gap with the magnetic field established by the current in the inductive component. By the action of electromagnetic torque, the generator absorbs mechanical power from the mechanical system, and the motor outputs mechanical power to the mechanical system. The two magnetic fields are established in different ways to form different types of motors. For example, if two magnetic fields are generated by a direct current, a DC motor is formed; two magnetic fields are respectively generated by alternating currents of different frequencies to form an asynchronous motor; one magnetic field is generated by a direct current, and the other magnetic field is generated by an alternating current, and a synchronization is formed. Motor.

The magnetic field energy of the motor is basically stored in the air gap, which causes the motor to connect the mechanical system and the electrical system, and achieve energy conversion. Therefore, the air gap magnetic field is also called a coupled magnetic field.

When a current flows through the motor winding, a certain flux linkage is generated and a certain amount of electromagnetic energy is stored in its coupled magnetic field. The amount of magnetic flux and magnetic field energy storage varies with the rotor current and rotor position, thereby generating electromotive force and electromagnetic torque to realize electromechanical energy conversion. This energy conversion is theoretically reversible, ie the same motor can be operated both as a generator and as an electric motor. However, in fact, after a motor is manufactured, due to the parameters and characteristics of the motor under two operating conditions, it is accurate to meet the objective requirements of the two operating states. Therefore, the same motor is not modified and redesigned. Change its running status arbitrarily.