For the partial paralleled dual active bridge (PPDAB) converter, in order to find out the two phase-shift angles which can minimize RMS current of the inductor under different load conditions, two algorithms are proposed in this paper. One is the improved particle swarm optimization (PSO) algorithm, and the other is the online optimization algorithm. In the improved PSO algorithm, the LTspice is called to avoid the calculation errors and the influence of parasitic parameters in high switching frequency. The other is the online optimization algorithm, which can improve the optimization accuracy in actual circuit. Additionally, a simple fuzzy algorithm is proposed to guarantee continuous output power. Furthermore, for eliminating the error of the delivered power in the actual circuit caused by the parasitic parameters of the devices, a PI control is proposed, which can be called in the improved PSO algorithm and the online optimization algorithm. Finally, the proposed PSO algorithm and the adaptive PI control are verified by simulation.