A Current-Controlled Tristate Boost Converter With Improved Performance Through RHP Zero Elimination

• Published in: IEEE transactions on power electronics 2009-03, Vol.24 (3), p.776-786
• Main Authors: Kapat, S., Patra, A., Banerjee, S.
• Format: Article
• Language: English
• Subjects: Applied sciences; Bifurcation; Capacitors; Circuit properties; Circuits; Clocks; Control systems; Control theory; Converters; Convertors; dc-dc power conversion; Electric currents; Electric potential; Electric, optical and optoelectronic circuits; Electrical engineering. Electrical power engineering; Electrical machines; Electronic circuits; Electronics; Exact sciences and technology; Experiments; Feedback loop; feedback systems; feedforward systems; Inductors; Intervals; Output feedback; Power electronics, power supplies; pulsewidth modulated power converters; Regulation and control; Signal convertors; Simulation; stability criteria; Switches; switching circuits; Switching converters; Transfer functions; transient response; Voltage; Voltage control
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2008.2008994

A novel current mode control scheme for the tristate boost converter circuit is proposed, which eliminates the zero in the right-half plane (RHP), 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 almost constant during the freewheeling interval when the additional switch is turned on. In the proposed controller, the peak value of the inductor current is controlled by peak current mode control using an outer voltage feedback loop, whereas the freewheeling current is controlled by the input voltage and the reference voltage feedforward path. Applying both feedback as well as feedforward control on the inductor current significantly improves the output voltage regulation, audio susceptibility, and transient responses. We show that the RHP zero is completely eliminated from the closed-loop control-to-output transfer function. This results in a very large bandwidth, and hence a superior dynamic performance. The latter is established by comparison with the voltage-mode- and current-mode-controlled classical boost converters that suffer from the RHP zero problem, as well as with other tristate boost converter control techniques like the constant charging interval and dual mode control, recently proposed in the literature. Significant superiority of the proposed scheme is established both through simulation and experimentation.