Capacitor Current Pulse Train Control Technique For Switching DC-DC Converter

Pulse train (PT) control technique realizes the output voltage regulation of switching dc-dc converter by using preset high and low power pulses according to the comparison results between reference voltage and output voltage. Without compensating network, PT control technique enjoys simple implementation, strong robustness, fast transient response, etc.So far, the mainly study focuses on PT control technique applying to switching dc-dc converters operating in discontinuous conduction mode (DCM). While PT control technique applying to switching DC-DC converters operating in continuous conduction mode (CCM), low frequency oscillation phenomenon will occur in inductor current and output voltage with small capacitor equivalent series resistance (ESR). Inductor current and output voltage range fluctuations, greatly reducing the performance of the converter. Although increased output capacitor ESR can shorten the phase difference between output voltage and inductor current, and supnpress low frequency oscillation phenomenon, but higher ESR brings higher output voltage ripple.In order to widen the application range of the PT control, this paper presents a capacitor current pulse train (CC-PT) control method. Unlike conventional pulse train (PT) control technique, CC-PT control technique achieves two sets of high and low control power pulses with the same frequency but different duty ratio by sampling capacitor current and compared with preset high, low reference currents.Both control properties of CC-PT controlled Buck converter operating in DCM and CCM are presented. The output power, pulse combinations, and its output voltage ripple of CC-PT controlled Buck converter operating in DCM, are analyzed in detail. For CC-PT controlled Buck converter operating in CCM, the principle of the low frequency oscillation suppressing, the transient response characteristics and the output voltage ripple are also presented. At the same time, the discrete iterative model of CC-PT controlled Buck converter operating in CCM is established.Finally, the experimental platforms of PT and CC-PT controlled Buck converter are constructed to verify the correctness of theoretical analysis. The results show that switching DC-DC converter under CC-PT controlle working in CCM has a superior steady-state and transient response characteristics than that of PT control.