Modular Fault Tolerant DC/DC Transformer Enabled by Natural Power Sharing

The use of a DC/DC Transformer (DCX), composed of low-power individual modules with automatic voltage and power sharing will be presented as a possible solution to increase the input voltage and output power ranges of DCX systems. The input voltage range will be increased through just Input Series - Output Parallel (ISOP) connection and the increased power handling capability will be achieved by Input Parallel - Output Parallel (IPOP) connection. With these modules, it is possible to achieve natural power and voltage sharing using only a common synchronization signal between modules. Thanks to this natural equalization, ISOP and IPOP concepts are extended to form a DCX with a matrix structure which will be tolerant to the loss of one module without compromising the power handling capabilities. The proposed topology is analyzed in detail, including the mechanisms that can affect the distribution of voltages and currents. A reliability analysis and the response of the modular system under a failure situation have also been included. The validation of this proposal has been carried out using a modular prototype for an input voltage and an output voltage of 56 V and 28 V respectively, for a rated power of 200 W, and for a switching frequency of 365 kHz.