Objectives Aiming at the stability problem of naval DC propulsion system, which has a serious proportion of power electronic devices, the stability analysis and controller parameter optimization method based on Middlebrook is proposed.

Methods Firstly, based on the Middlebrook impedance ratio stability criterion, the small-signal output impedance of the DC bus and the small-signal input impedance of the inverter and the motor are deduced and established through the simplification of the system model, the linearization of the nonlinear system, and the dq transformation of the three-phase AC system, etc. Then the controller parameters are optimized by particle swarm algorithm to minimize the value of support capacitance under the condition of ensuring system stability. Finally, the simulation model of DC propulsion system of the ship is constructed to simulate and analyze the influence of support capacitance and equivalent resistance and equivalent inductance of DC bus on the stability of the system.

Results Simulation results show that after optimizing the controller parameters by particle swarm algorithm, the system stability margin is obviously improved, which in turn reduces the value of support capacitance, and will be beneficial to reduce the overall size of the converter of the ship's DC propulsion system.

Conclusions The research results can provide a reference for the study of voltage oscillations and their suppression in integrated power systems with a serious share of power electronics.