Principle Of Ignition Coil

Usually, there are two sets of coils inside the ignition coil, the primary coil and the secondary coil. The primary coil is wrapped with thicker enameled wire, usually around 0.5-1mm enameled wire for around 200-500 turns; The secondary coil is wrapped with thinner enameled wire, typically around 15000 to 25000 turns of enameled wire of around 0.1mm. 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 (circuit breaker). One end of the secondary coil is connected to the primary coil, and the other end is connected to the output end of the high-voltage line to output high-voltage electricity.
The reason why the ignition coil can turn low voltage electricity on the vehicle into high voltage is due to the same form as ordinary transformers, where the primary coil has a larger turn ratio than the secondary coil. However, the working mode of the ignition coil is different from that of an ordinary transformer. The working frequency of an ordinary transformer is a fixed 50Hz, also known as a power frequency transformer, while the ignition coil operates in the form of pulses, which can be seen as a pulse transformer. It repeatedly stores and releases energy at different frequencies according to different engine speeds.
When the primary coil is powered on, a strong magnetic field is generated around it as the current increases, and the iron core stores 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 induces 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.