There are usually two sets of coils in the ignition coil, the primary coil and the secondary coil. The primary coil is made of thicker enameled wire, usually, around 0.5-1mm enameled wire around 200-500 turns; the secondary coil is made of thinner enameled wire, usually around 0.1mm around 15000-25000 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 switch 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 convert the low-voltage electricity on the vehicle into high-voltage is that it has the same form as the ordinary transformer, and the turn ratio of the primary coil is larger than that of the secondary coil. However, the working model 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 the form of a pulse, which can be regarded as a pulse transformer. The rotational speed repeatedly stores and discharges energy at different frequencies.
When the primary coil is powered on, a strong magnetic field is generated around as the current increases, and the iron core stores the magnetic field energy; when the switching device disconnects the primary coil circuit, the magnetic field of the primary coil decays rapidly, and the secondary coil A high voltage will be induced. The faster the magnetic field of the primary coil disappears, the greater the current at the moment when the current is disconnected, and the greater the turns ratio of the two coils, the higher the voltage induced by the secondary coil.