A novel current controlled tri-state boost converter with superior dynamic performance

A novel current mode control of tri-state boost converter is proposed, which eliminates the zero in the right-half plane and improves the dynamic performance. The tristate boost converter contains an additional switch across the inductor. Within a clock cycle, the inductor current first rises during the ON interval of the main switch, then falls during the OFF or capacitor charging interval, and finally remains constant during the freewheeling interval when the second switch is turned on. In the proposed controller, the peak value of the inductor current is controlled by peak current mode control whereas the freewheeling current is dependent on the reference voltage. The direct control of the inductor current results in a larger bandwidth due to the fast inner loop and thereby a superior dynamic performance is obtained. The latter is established by comparison with that of voltage mode and current mode controlled classical boost converters which suffer from the RHP zero problem, as well as with other tri-state boost converter control techniques like the constant charging interval and dual mode control.