INDUCTIVE IGNITION CIRCUIT

摘要

An inductive ignition circuit (10) especially adapted for use with micro-turbine and other small-sized turbine engines such as are used in electric generators. The inductive ignition circuit (10) includes a flyback transformer (14), a drive circuit (16) for energizing the primary (22) of the transformer (14), and a control circuit (18) that temporarily disables the drive circuit (16) once the transformer primary (22) has been sufficiently energized. The drive circuit includes a switching transistor (20) which is biased on to draw current through the primary (22). The control circuit (18) includes two feedback circuits (42,44), one of which initiates disabling of the transistor (20) to cause the transformer flyback and the second of which sets the spark rate. The first feedback circuit (42) monitors the primary current and disables the transistor (20) once the current exceeds a pre-selected level. The second feedback circuit (44) uses a portion of the flyback energy obtained via a feedback winding (30) to maintain the transistor disabled for a period of time that can be selected over a wide range of values. The feedback winding (30) is used to provide positive bias to the transistor (20) during switching on of the transistor and is used by the second feedback circuit (44) during flyback to provide charging current to an RC timer circuit (64) in the second feedback circuit. This timer circuit (64) includes a capacitor (68) which is used to hold the transistor (20) off until the capacitor (68) has discharged below a pre-selected level.