Research on DC/DC converter topology for high-input-voltage satellite system applications

Abstract

Satellite DC/DC power converters are required to have a high reliability and to comply the EMC requirements. The high reliability requirement limits the DC/DC converter’s design in terms of its structure and the number of applicable FET switches and diodes, and the heritage topologies that have been verified for a long time in these environments can be applied to the satellite DC/DC converter. Moreover, large EMI filters have been inevitably needed for the satellite DC/DC converter to meet the EMC requirement. In addition, due to the size and weight limitation of the satellite electronic unit, the satellite DC/DC converter should have a high-power-density design. However, EMI filter usually occupies large portion of the DC/DC converter board. The EMI noise is directly related with the level of di/dt and the pulsating ripple of input current waveform. Therefore, it is beneficial to minimize the input current ripple significantly for the smaller sized EMI filter. The conventional ACF topology has a zero-voltage-switching capability, better EMI performance and more reduced switching loss than other heritage topologies. However, it has still pulsating input current waveform with high di/dt level and high switch voltage stress, which is disadvantageous in terms of the EMI filter size and satellites with high input voltage. In this dissertation, a new ACF topology with a continuous input current waveform is proposed to overcome these drawbacks. In addition, voltage stresses of main switches are relieved by applying a two-series connected structure. This two-series structure will enhance the reliability of FET switches which is crucial for high-voltage satellite applications. Therefore, the proposed DC/DC converter topology would be more suitable for high-voltage satellite applications with stringent requirements of reliability, EMC, and high-power density.