Study On Marine Shaft Motor Control System Based On Model Prediction

Marine hybrid propulsion system can not only effectively reduce the cost of shipping industry and pollution,but also improve efficiency.In this thesis,the ship shaft motor is taken as the research object,and the control strategy of the energy feedback inverter in different propulsion modes of the marine hybrid propulsion system is studied to realize the free switching of the energy bidirectional flow.Firstly,the mathematical model of double PWM energy feedback converter is established.The direct power and torque control strategy based on switching table(ST-DPTC)is studied,and the power feedback principle is used to control the energy feedback converter to realize the bidirectional energy flow.Based on the analysis of simulation,it has the problems of motor torque,flux and power ripple.An improved control strategy is proposed to improve the stability of the system.Secondly,the direct power and torque control strategy based on model prediction(MP-DPTC)is studied.The reducing MPC control complexity algorithm is introduced in it to simplify the algorithm and select the optimal voltage vector quickly.Double vector control is introduced in each sampling period to reduce the motor torque and flux ripple,and the optimal duty cycle control algorithm is proposed to coordinate the time between the zero and nonzero voltage vector.Compared with the ST-DPTC,it can reduce the current ripple,torque and flux ripple,and has good tracking and robustness.Finally,the power and control platform of the hybrid propulsion system is designed and carried out under different operating modes.It flexibly solves the power allocation between the main motor and the shaft motor,and realizes the free switching of the shaft motor between the electric and generating states.Based on DSP28335,an energy feedback unit EMI filter board and a three-phase software phase-locked loop are designed to ensure the quality of power generated by shaft generator and grid connected power.Using S7-200 SMART controller,the main circuit,the control circuit,the programming of control platform and MCGS PC are designed.The ST-DTC and MP-DTC algorithm are applied to the experimental platform of energy feedback unit respectively,the system runs stably,switches stably and has small dithering.The performance of marine shaft motor control algorithm based on model prediction is verified.