Research On High Frequency Power Converter With Digital Control And Resonant Gate Driver

The rapid development of power electronic power devices has made converters tend to be small-sized,high-frequency,and high-power density,and high-frequency and ultra-high-frequency power conversion technologies have attracted widespread attention.In low-voltage input converters,synchronous rectifier buck converters are widely used due to their simple structure and few components.In high-voltage input converters,half-bridge LLC resonant converters are widely used due to low loss,high efficiency,and high power density.When the operating frequency of the converter increases to more than MHz,the traditional drive losses of the MOSFET will increase significantly,including drive losses and switching losses.The resonant gate drive is an effective way to solve the above problem of traditional gate driver,using the external inductance and the input capacitance of the MOSFET to tranfer energy to reduce the driving loss and increase the driving speed.Firstly,the research background and domestic and foreign research status of resonant drive technology are introduced.The actual equivalent model of MOSFET and hard switching process is analyzed.Many defects in the traditional voltage source driving in the high-frequency converters are pointed out.The concept of resonant gate drive is introduced.The working principles,advantages and disadvantages of several existing resonant driving circuits,which are mainly referenced in this paper,are given.The concept of resonant gate drive chip is proposed.Secondly,some research has been done on the resonant gate drive circuit of the synchronous Buck converter in low voltage application.In this paper,three different resonant gate drive circuits are used to drive the MOSFETs of the synchronous Buck converter when the switching frequency increased to 1MHz.For the control MOSFET,the optimal designinvolving a tradeoff between the drive circuit loss and switching loss,while for the synchronous MOSFET,the optimal design facing a tradeoff between drive circuit loss and body diode,conduction loss.Finally,some research has been done on the resonant drive circuit of the synchronous rectifier half-bridge LLC converter for high voltage application.In this paper,two different resonant drive circuits are used to respectively drive the control tubes of the half-bridge structure and The synchronous rectifier tubes of the common source structure when the resonant frequency is increased to 1MHz.For the control MOSFET,the optimal design considers the tradeoff between drive circuit loss and switching loss,while for the synchronous Rectifier MOSFET,the optimal design considers the tradeoff.The working principle of the two resonant driving circuits is analyzed in detail.The closed-loop design is completed by DSP and CPLD,and the relevant experimental waveforms and data are obtained.