The invention relates to a resonant pole-type
soft switching inverter circuit based on auxiliary commutation of a
transformer. The main circuit comprises a DC power supply, a three-phase
pulse width modulation inverter and a three-phase resistance-
inductance load, wherein three groups of the same auxiliary resonant circuits are arranged between the DC power supply and the three-phase
pulse width modulation inverter; the three groups of the auxiliary resonant circuits are corresponding to the A phase, the B phase and the C phase of a three-phase
transformer; each resonant circuit group comprises one single-phase
transformer, two auxiliary switches with antiparallel diodes, one resonant
inductor and four auxiliary diodes. A large-capacity grading
capacitor serially connected in a DC link is avoided, and the neutral point
potential change problem of the inverter is solved;
inductance and current thresholds related to control of auxiliary switches do not need to be set, and no extra detection and timing circuit is needed; and the transformer is used for auxiliary commutation, each phase of
auxiliary circuit is only provided with two auxiliary switches, and the auxiliary switching device and the main switching device of the inverter can realize
soft switching.