ISOLATED DC/DC CONVERTERS FOR WIDE OUTPUT VOLTAGE RANGE AND CONTROL METHODS THEREOF

摘要

An efficient control method for an isolated multilevel DC/DC resonant converter (700, 800, 1000, 1400, 1600, 1650, 1700, 1750, 1800, 2100) achieves a wide output voltage range with a narrow device switching frequency range, relative to the output voltage range and the device switching frequency range of the prior art. At any given time, a control circuit (801, 1401, 1601, 1651, 1701, 1751, 1801, 2101) selects one of three different modulation schemes to operate the primary-side switching devices of the resonant converter (700, 800, 1000, 1400, 1600. 1650, 1700, 1750, 1800, 2100) based on at least one of output voltage (Vo), output current (Iο), input signal, and one or more external control signals. Together with a selected device switching frequency, the three modulation schemes generate different voltage waveforms to a primary-side transformer, which are coupled to the secondary-side to provide different output voltages (Vo).