Aiming at overcoming the problem that the switching loss of the solid-state transformer (SST) increases greatly at high frequency, the auxiliary resonant commutated pole inverter (ARCPI) is used to achieve soft-switching and improve the efficiency of the SST end-side. However, compared to the hard-switching inverter, the ARCPI contains two additional auxiliary commutation circuits (ACCs), which will increase the cost and volume of SST. To reduce unnecessary ACC, a novel ARCPI topology and its simplified modulation strategy is proposed in this paper. Two bidirectional switches are used to ensure that the ACC can provide soft-switching conditions for high frequency bridge leg at any time. Based on the single polarity PWM modulation strategy, an ACC of one phase bridge leg is omitted, thus the efficiency of the ARCPI is improved and the cost is reduced. Finally, the simulation model is built and the results validate the effectiveness of the analysis in this paper.