Working principle of alternator

The basic principle of alternator power generation is the principle of electromagnetic induction. The belt drives the rotor to rotate, generates rotating magnetic field, cuts the stator coil winding, and the star connected stator winding generates sinusoidal alternating voltage. After being rectified by the full bridge rectifier, it outputs DC power to supply the power consumption of the whole vehicle. The rotor magnetic field can be generated by the permanent magnet, but it is uncontrollable and the excitation current is small. Therefore, the magnetic field is generated by energizing the excitation coil of the rotor. The number of turns of the coil and the size of the excitation current determine the strength of the magnetic field. Changing the size of the excitation current can adjust the magnetic field strength and then control the induced voltage.

Direct current is required for battery charging and the electrical system on the vehicle, so the alternating voltage generated by the generator must be rectified into direct current voltage. In order to make the positive half wave and negative half wave of alternating voltage can be effectively used for power supply, full bridge rectification can be adopted. The bridge rectification circuit is composed of 6 diodes, each branch is composed of 2 power diodes, one of which is connected to the positive side, The other is connected to the negative side.