Principle of the ignition coil

Principle of the ignition coil：

 

There are two sets of coils in the normal ignition coil, the primary coil and the secondary coil. The primary coil uses a thick enameled wire, usually with about 0.5-1 mm enameled wire around 200-500 turns; the secondary coil uses a thin enameled wire, usually about 0.1 mm enameled wire around 15000-25,000 turns. One end of the primary coil is connected to the low-voltage power supply (+) on the vehicle, and the other end is connected to the switching device (disconnector). One end of the secondary coil is connected to the primary coil, and the other end is connected to the high-voltage line output to output high-voltage electricity.

The reason that the ignition coil can change the low-voltage electricity on the car to high voltage is because it has the same form as the ordinary transformer. The primary coil has a larger turn ratio than the secondary coil. However, the ignition coil works differently from ordinary transformers. The operating frequency of ordinary transformers is fixed at 50Hz, also known as power frequency transformers. The ignition coils work in pulse form and can be regarded as pulse transformers. The rotation speed repeatedly stores and releases energy at different frequencies.

When the primary coil is powered on, a strong magnetic field is generated around the current 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 rapidly decays, and the secondary coil High voltages can be induced. The faster the magnetic field of the primary coil disappears, the larger the current at the moment of current disconnection, and the larger the turns ratio of the two coils, the higher the voltage induced by the secondary coil.