Presentation Description: High voltage Buck converters are typically using a single switch, referred to primary ground. When input voltage reaches values higher than 600V, then it is necessary to select appropriate high voltage (HV) field effect transistor (FET), and in this case the selection falls over silicon carbide (SiC) FETs or another wide band gap component. Three level Buck topologies are helping in these situations because they split the input voltage among two or more switches in series. This presentation shows how it is possible to use standard 600V FETs in a Buck converter to achieve 800V+ input, by leveraging a coupled inductor that automatically balances the center point of the input capacitors, therefore halving the stress on each series FET. In addition, boundary mode modulation (transition between discontinuous-conduction-mode (DCM) and continuous-conduction-mode (CCM)) is used to avoid reverse recovery from the FETs and enable the use of cost-effective ultrafast silicon diodes.
