DC–DC Converter and On-board DC Microgrid Stability

The transformer rectifier unit which offers voltage control capability also has a DC–DC converter connected in series to the rectifier. The dual active bridge (DAB) converter is formed by two full bridges, two capacitors, and a high-frequency transformer for galvanic isolation. In order to achieve better soft-switching performance than the DAB converter, a resonant tank can be added to the primary stage circuit. As the onboard power electronics increase, the scale of electrical power distribution system becomes much larger and the system structure becomes more complex. The combination of source and load subsystems with different behaviors could make the system unstable, especially for those load subsystems, which perform as constant power loads (CPLs). To avoid the instability introduced by the negative incremental impedance characteristic of CPL, the design of system needs to be well considered while the stability analysis needs to be carried out for predicting system stability.