Digital DC CDI for Small Engines: Low Cost Solution and Challenges with 8 Bit Microcontroller

Emerging markets like India is very cost sensitive for small engines like motorcycle. Capacitive discharge Ignition (CDI) with carburetor is popular low cost solution with good engine performance. CDI system accumulates charge inside the ignition capacitor, until a point at which a signal allows to release discharge of the stored charge to the spark plug through high tension coil.

This paper will focus on single spark digital two teeth DC CDI solution and below design challenges with two sparks.

1. 1
   Higher power dissipation in step up fly back converter
2. 2
   Need higher CPU speed, flash size and restrictions on engine map profile for advance angles

This paper will elaborate above problems and their solutions with test results for optimizing solution cost and achieve performance. Solutions include, exploring 8 bit microcontroller peripherals usage and smart software to boost MCU performance for engine dynamic conditions and to achieve lower losses in flyback converter.