High voltage-gain transformerless single-stage boost converter requires extreme duty ratios. Hysteretic control can be a solution to achieve this goal, otherwise unaffordable with common PWM integrated circuits. With this technique voltage gains around 100, and duty cycles higher than 99% are feasible. As a possible application, a typical 50 W halogen-based car spot-light, is replaced by an array of 200-300 standard LED’s in series consuming 8 -12 W. Although series connection simplifies current control and dimming, a high voltage current-source is required.
High voltage-gain transformerless single-stage boost converter requires extreme duty ratios. Hysteretic control can be a solution to achieve this goal, otherwise unaffordable with common PWM integrated circuits. With this technique voltage gains around 100, and duty cycles higher than 99% are feasible. As a possible application, a typical 50 W halogen-based car spot-light, is replaced by an array of 200-300 standard LED’s in series consuming 8 -12 W. Although series connection simplifies current control and dimming, a high voltage current-source is required.