The Research On Experiment Device Of Ship PMSM Propulsion System

With the increasingly environmental standards of the international maritime organization and oil price, electric propulsion system with high efficiency has become the mainstream of modern ship power mode. Permanent magnet synchronous motor (PMSM) has the advantages of high efficiency and high reliability, is ideal propulsion motor in the electric propulsion system. PMSM has been widely applied in the ship propulsion system, so it is necessary to research on PMSM propulsion system by simulation and practical examination.Direct torque control (DTC) is high performance AC speed control technology which does not require complex coordinate transformation. As long as the proper voltage vector has been selected, motor speed can quickly follow given value, and the system can rapid response to torque changes. PMSM and the principle of DTC are introduced in the paper in detail, and the model of PMSM-DTC system has been set up in Simulink to do the research. The simulation results show that there will be a poor start characteristic and the problem of large torque ripple in the conventional PMSM-DTC system.There exists reluctance negative sequence torque and generator braking torque during the PMSM startup process. Those may result in reverse electromagnetic torque and motor reverse rotation. For the selected PMSM, it is unable to change the motor parameters to reduce reluctance negative sequence torque and generator braking torque. So in the startup phase, we have to select the voltage vector which can increase flux rapidly and limit torque increment,and change torque feedback, to ensure that PMSM can achieve direct positive start.This paper analyzes the causes of torque ripple in detail, adopts fuzzy control method to optimize the system. Replace the hysteresis comparator and space voltage vector selection table with fuzzy controller, send the flux and torque error and stator flux position into fuzzy processing, the controller output more reasonable and accurate voltage vector number according to the fuzzy rules.According to the propeller characteristics and the mutual influence between ship and propeller, the mathematical model of ship-propeller is established. The simulation result verified that this model meet up with the real ship-propeller characteristics. Then set up the PMSM propulsion model with propeller load in Simulink. Ship start and reverse, which are the two relatively heavy conditions during the whole ship motion, are simulated and observe the dynamic and steady-state performance of propulsion system, and the impact of different ways of operation on propulsion system.Finally, the experiment device of PMSM propulsion system has been set up to make the actual examine of PMSM propulsion system and verify the feasibility and rationality of the simulation model. Write PC control software which contains ship-propeller model to control system operation, and control DC generators to provide propeller load torque for propulsion system. The experimental results validate the simulation results, that uses hierarchical start-up and brake can reduce the impact force on propulsion motor.