Control of a cascade boost converter with a single active switch

The development of new technologies is requiring wider conversion ratios. A possible solution to this problem is to use n-stages connected in cascade; however, the major drawback is that a more complex control circuitry is required. An alternative solution is to use a cascade boost converter with a single switch. A controller is developed using average current-mode control. It is shown that the transfer function of the first inductor current/duty ratio is a minimum phase transfer function; thus, this current is selected for feedback purposes. For the inner loop, a current gain and a high gain compensator are selected. For the output loop, a conventional PI-controller is used which provides good regulation characteristics. Experimental results are given for a 100 W switching regulator with step changes between full and 40% of load.