Research On Quasi Sliding Mode Control Applied To High Efficiency On-Chip Boost Converter

Boost converter is a basic power converter in modern electronic systems. It is widely adopted in solid-state lighting and high voltage biasing. The urgent demands of modern electronic systems on energy saving and environmental protection make the solid-state lighting emerge to replace conventional mercury based lamps. Thus, improving the conversion efficiency and increasing the integration of boost converter are important to save energy and drive the solid-state lighting industry.To stabilize traditional PWM controlled boost power converter, complex compensation networks are always required, which means extra external components as well as higher system cost. Besides, the conversion efficiency is degraded during light load condition due to fixed frequency architecture. Sliding mode controlled power converters have the merits of no loop compensation requirement and better dynamic response compared with conventional linear mode controlled ones. However, the output current of the boost converter is discontinuous, and as a result, conventional hysteretic sliding mode control is not suitable. Therefore, adaptive on-time control(AOT), a quasi sliding (QS) mode control, was proposed in this dissertation. With that, the converter runs in efficiency improved pulse frequency modulation (PFM) automatically during light load operation.Based on the two dimensional phase plane analysis, the criterion to stabilize the AOT-QS boost converter was derived; a simple adaptive on-time generator was proposed to make the power converter operate in quasi fixed frequency under inductor continuous conduction mode so as to control the output voltage ripple. After improving its feedback structure, AOT-QS boost converter is designed to be a voltage controlled voltage source. With that, a high dimming ratio high power LED drive controller was designed.Considering the emergence of low voltage batteries like fuel cells, projected off-time on-time quasi sliding mode (PFT-QS) control is proposed. With that, bigger maximum duty cycle can be realized compared with AOT-QS control. Its stability criterion and loop transfer function were derived. A general-purpose boost regulator with on-chip DMOS was implemented using the proposed PFT-QS control method. Test results show the proposed on-chip boost regulator outperforms the conventional current mode controlled one in aspects of conversion efficiency and load transient response.In order to further increase the integration level, circuit techniques like on-chip compensation, current sensing, over current limit were also discussed. Adopting these circuits, the proposed high integration PFT-QS boost regulator was designed, which integrated the components as more as possible on the chip besides the power devices and feedback network. The final boost regulator design was verified by Spice simulation.