Study On The Digital Peak Voltage-Peak Current Control Of Switching-Mode Power Supply

Due to the high power consuming characteristic of the next generation processors, the regulation requirement for power converter systems becomes more and more demanding in industry. Since it has the advantages of good programmability, flexibility and reliability, digital control system has the potential to achieve high performance control of switching-mode power supply (SMPS). The motivation of this research is to explore new digital control algorithms for SMPS to achieve high dynamic performance control. Two advanced digital control algorithms are summarized in this thesis, and made an introduction and an analysis on digital Peak Voltage-Peak Current (DPV-PC) control algorithm to improve its completion in theory.DPV-PC control of SMPS combines advantages of Peak Voltage-Peak Current mode control, including overload current protection and robust dynamics, and advantages of digital implementation, such as programmability, flexibility, and scalability. In Continuous Conductive Mode (CCM), DPV-PC control technique with different modulation methods (single-edge and dual-edge modulation) is studied on Buck converter topology. In the digital control loop of switching converter, the time delay for digital operations is inevitable and it is at least one switching cycle. To overcome this time delay, the algorithm called an improved digital Peak Voltage-Peak Current (IDPV-PC) control is presented and comprehensively studied.Small signal model of Buck converter with DPV-PC control is derived by using state space average method. And the output impedance, line-to-output and control-to-output transfer functions are obtained subsequently. Theoretic analysis and simulation results show that IDPV-PC control technique has a better transient control performance for power switching converter than DPV-PC control technique.The comparison between the transient behaviors of DPV-PC control and IDPV-PC control is performed by simulation results, from which we conclude that IDPV-PC control has faster transient response speed than DPV-PC control.