A study on wide operation range DC-DC converter

DoctorIn this dissertation, a multiple switching-mode for a series-resonant half-bridge dc-dc converter and the hybrid type full-bridge dc-dc converter are presented. First, the proposed multiple switching scheme for series-resonant half-bridge dc-dc converter changes switching modes to improve power efficiency for a wide output range, especially in the low output power range. This multiple switching scheme is composed of three different switching modes varying depending on the output power.Second, the proposed hybrid type full-bridge dc-dc converter has an advantage to enhance the input voltage range. In this converter, only adding one blocking diode and one clamp capacitor to the conventional full-bridge dc-dc converter, the proposed dc-dc converter enables the hybrid control schemes. If the input voltage is changed, the proposed converter changes its control scheme and this feature enhance the input voltage range. Soft switching technique reduces switching losses and reverse recover problem can be solved. The operation and analysis of each mode are presented.The overall control circuit of the prototype was implemented by using a single-chip microcontroller. With a multiple switching mode, high efficiency is achieved over an entire output power region. Experimental results on a 1.2 kW prototype are presented to confirm the performance of the proposed multiple switching scheme for a series-resonant half-bridge converter