Working principle of ignition coil:

There are two groups of coils in the usual ignition coil, primary coil and secondary coil. Thick enameled wire is used for the primary coil, usually with 0.5-1 mm enameled wire for about 200-500 turns; The secondary coil is made of thin enameled wire, usually with 0.1 mm enameled wire for about 15,000-25,000 turns. One end of the primary coil is connected with the low-voltage power supply (+) on the vehicle, and the other end is connected with the switching device (breaker). One end of the secondary coil is connected with the primary coil, and the other end is connected with the output end of the high-voltage line to output high-voltage electricity.

The reason why the ignition coil can change the low-voltage electricity on the vehicle into high voltage is that it has the same form as the ordinary transformer, and the turns ratio of the primary coil is larger than that of the secondary coil. However, the working mode of the ignition coil is different from that of the ordinary transformer. The working frequency of the ordinary transformer is fixed at 50Hz, also known as the power frequency transformer, while the ignition coil works in pulse form, which can be regarded as a pulse transformer, which repeatedly stores and discharges energy at different frequencies according to different engine speeds.

When the primary coil is connected to the power supply, a strong magnetic field is generated around with the increase of current, and the iron core stores magnetic field energy; When the switching device disconnects the circuit of the primary coil, the magnetic field of the primary coil decays rapidly, and the secondary coil will induce a high voltage. The faster the magnetic field of the primary coil disappears, the greater the current at the moment of current disconnection, and the greater the turn ratio of the two coils, the higher the voltage induced by the secondary coil. exist