Using the bilevel optimization (BIO) scheme, this paper presents a time-optimal path planner for autonomous underwater vehicles (AUVs) operating in grid-based environments with ocean currents. In this scheme, the upper optimization problem is defined as finding a free-collision channel from a starting point to a destination, which consists of connected grids, and the lower optimization problem is defined as finding an energy-optimal path in the channel generated by the upper level algorithm. The proposed scheme is integrated with ant colony algorithm as the upper level and quantum-behaved particle swarm optimization as the lower level and tested to find an energy-optimal path for AUV navigating through an ocean environment in the presence of obstacles. This arrangement prevents discrete state transitions that constrain a vehicle’s motion to a small set of headings and improves efficiency by the usage of evolutionary algorithms. Simulation results show that the proposed BIO scheme has higher computation efficiency with a slightly lower fitness value than sliding wavefront expansion scheme, which is a grid-based path planner with continuous motion directions.

An active inter-phase reactor（AIPR）is often employed to inject triangle current to improve the input current quality of double star diode rectifier. Due to the existed leakage inductance of transformer, the input current harmonics suppression ability of the injected triangle current would be weaken. In this paper, the current commutation process of the double star diode rectifier with AIPR is analyzed initially. Then, according to the relation between the input current and output current of the double star transformer, the relation between the leakage inductance and the input line current of double star diode rectifier with AIPR is established. Such factors like the input current THD, the input current lag angle and power factor of the double star diode rectifier with AIPR, their relations with the leakage inductance are also obtained. The theoretical analysis demonstrate that the leakage inductance increase the input current THD and lag angle. It indicates that the leakage inductance decrease the displacement factor and power factor. To ensure the input current THD is less than 5% and the power factor is more than 0.998, the leakage inductance factor KLs should be less than 0.22. Simulation results verify the theoretical analysis.