An accurate circuit of PWM/PFM mode converting and a circuit of auto-adaptively adjusting dimension of power transistor are described.The duty cycle of the signal when the control mode converts can be gained accuratel...An accurate circuit of PWM/PFM mode converting and a circuit of auto-adaptively adjusting dimension of power transistor are described.The duty cycle of the signal when the control mode converts can be gained accurately by using ratios of currents and capacitances,and an optimal dimension of power transistor is derived with different loads.The converter is designed by 0.35μm standard CMOS technology.Simulation results indicate that the converter starts work at 0.8 V input voltage.Combined with synchronized rectification,the transfer efficiency is higher than 90%with full load range,and achieves 97.5%at rating output.展开更多
With further population of gallium nitride(GaN)devices,traditional boost topology has an opportunity to obtain a higher power density with a higher switching frequency.However,high-frequency switching loss of GaN devi...With further population of gallium nitride(GaN)devices,traditional boost topology has an opportunity to obtain a higher power density with a higher switching frequency.However,high-frequency switching loss of GaN devices has become one important factor restricting improvement of converter efficiency.Aiming at improving efficiency of synchronous rectification boost topology,this paper first discusses advantages of boost converter operating in boundary conduction mode(BCM).In order to fully ensure realization of soft switching in BCM mode,this paper has carried on indepth mathematical modeling analysis to the realization process of soft switching.Conclusion points out implementation range of soft switching can be extended by prolonging conduction time of synchronous rectification.Finally,an experimental prototype with rated power of 500 W is built to verify theoretical analysis.By ensuring implementation of soft switching in BCM mode,peak efficiency of prototype reaches 98.2%.Correctness of theoretical analysis in this paper is verified.展开更多
基金Supported by National Youth Science Foundation of China(No.60806010)
文摘An accurate circuit of PWM/PFM mode converting and a circuit of auto-adaptively adjusting dimension of power transistor are described.The duty cycle of the signal when the control mode converts can be gained accurately by using ratios of currents and capacitances,and an optimal dimension of power transistor is derived with different loads.The converter is designed by 0.35μm standard CMOS technology.Simulation results indicate that the converter starts work at 0.8 V input voltage.Combined with synchronized rectification,the transfer efficiency is higher than 90%with full load range,and achieves 97.5%at rating output.
文摘With further population of gallium nitride(GaN)devices,traditional boost topology has an opportunity to obtain a higher power density with a higher switching frequency.However,high-frequency switching loss of GaN devices has become one important factor restricting improvement of converter efficiency.Aiming at improving efficiency of synchronous rectification boost topology,this paper first discusses advantages of boost converter operating in boundary conduction mode(BCM).In order to fully ensure realization of soft switching in BCM mode,this paper has carried on indepth mathematical modeling analysis to the realization process of soft switching.Conclusion points out implementation range of soft switching can be extended by prolonging conduction time of synchronous rectification.Finally,an experimental prototype with rated power of 500 W is built to verify theoretical analysis.By ensuring implementation of soft switching in BCM mode,peak efficiency of prototype reaches 98.2%.Correctness of theoretical analysis in this paper is verified.
