Direct-current bus variable-structure doubly-fed strong excitation converter

The invention discloses a direct current bus variable structure double-fed strong excitation converter which is composed of a network side two-level converter, four sets of DAB converters, two sets of series-parallel switching circuits and a rotor side NPC type three-level inverter, and the four sets of DAB converters and the two sets of series-parallel switching circuits jointly input direct current voltage to form two sets of output voltage capable of being switched in a series-parallel mode. The rotor side NPC type three-level inverter is connected to a positive direct current bus and a negative direct current bus of the NPC type three-level inverter, and the rotor side NPC type three-level inverter carries out closed-loop control on the rotor current of the DFIG. According to the forced excitation converter, a variable-structure direct-current bus is constructed by using a dual-active bridge converter and a series-parallel switching circuit, so that the voltage of the rotor-side direct-current ...