Research On Charge Controlled Interleaving Buck Converter

The loads using pulse current sources require that the power supply has high current precision,fast transient response,small output current/voltage ripple and large output current.Multi-phase interleaving buck converter is widely used in pulse current sources because of its advantages in topology.When multi-phase interleaving buck converter and suitable control methods are combined,the converter will have excellent transient performance and stability to satisfy the requests of loads.Therefore,it is significant to research the multi-phase interleaving buck converter and its control methods used in pulse current sources.Combining current mode control and interleaving buck converter,the small signal models of peak current control and charge control are established correspondingly.By comparing their differences and similarities,the unified model of the two control methods is proposed.Based on the unified model,the stability and transient performance of the two control methods is analyzed comparatively in frequency domain and time domain.It is proved theoretically that charge control has wider stability region and superior transient performance than peak current control.Finally,the simulation and experiment results prove the validity of the theoretical analysis.Dimming strategy with pulse width modulation(PWM)and charge controlled interleaving buck converter is combined to output pulse current with fast rising/descending edge.The operation principles of the converter employing two PWM dimming strategies,including bilevel dimming strategy and switching dimming strategy,are analyzed.The transient performances of the converter employing the two dimming strategies are analyzed comparatively by simulation and experimental results.Research results show that the output current rises/descends stably and slowly when the converter employs bilevel dimming strategy,and the output current rises/descends rapidly with small overshoot on the rising edge when the converter employs switching dimming strategy.Finally,to restrain the unbalance of current sharing in charge controlled interleaving buck converter,the expression of inductor average current containing the on-resistance and integral capacitance is derived.Based on the expression,the causes resulting in unbalance of current sharing are analyzed.The current sharing control method by realizing the zero voltage switch(ZVS)of the synchronous switch is applied to charge controlled interleaving buck converter.Its operation principle is analyzed in detail.Based on the current sharing control method by realizing the ZVS of the synchronous switch,the improved current sharing control method is proposed to further restrain the unbalance of current sharing and improve the current sharing in light load and heavy load apparently.The current sharing effectiveness is analyzed comparatively and the theoretical analysis is verified by the simulation results.