Research On Ship PMSM Control Of Vector Control Based On Sliding Mode Observer

The marine permanent magnet synchronous motor (PMSM), with the advantages of simple structure, small size, high efficiency and stable operation, is widely used as the marine propulsion motor in the electric pod propulsion system. The podded propulsor works under water. Being influenced by the temperature, humidity, vibration, chemical substance and strong electromagnetic, it result in the interference on the connector of the sensor, cable and the devices of the sensor. It will damage the accuracy of the sensor and cause the inconvenience of maintenance. Therefore, this thesis focuses on the operation of sensorless PMSM based on sliding-mode observer under the performance of a propeller load. The research contents are as follows:Build a PMSM mathematical model under different coordinate systems and do a research on the PMSM vector control method, analyze the transformation of coordinate systems and the principle and implementation method of Space vetor pulse width modulation. Compare the advantages and disadvantages of various control strategies which includes id=0, cosΦ=1、 constant flux linkage、peak torque current ratio implementation control、weak magnetic control and so on. And the id=0 control strategy has been chosen as the control strategy of this thesis.The performance of a propeller load and fit the propeller parameters will be analyzed. By building a mathematical model based on the performance of a propeller load and the simulation model of PMSM vector control based on the performance of a propeller load under Simulink, the response curve of motor speed, torque and electricity under the ahead condition will be analyzed. Meanwhile, the effectiveness of the model will be verified.Analyze the basic principle of sliding mode variable structure and point out that the arithmetic of sliding mode variable structure has the advantages of quick response speed and strong robustness. However, due to the changing of state point around the sliding surface, it has the inherent chattering phenomenon. By combining the theory of sliding mode variable structure with the PMSM rotor position estimation algorithm, the sliding-mode observer based on the error of stator current is built to estimate the rotor position and speed of PMSM operation. Due to the discontinuity of switch function in traditional sliding-mode observer which makes estimated value larger dithering, the design of a counter potential estimate value feedback is introduced into the stator current observation new sliding mode observer(SMO) in the calculation of the rotor position estimation method.Finally, through the simulation experiment, the results based on new SMO of this paper designer show rapid response speed, obvious tracking effect and good robustness at speed mutation, load torque mutation, within the system parameter change conditions and better estimate the motor rotor position and speed. At the same time, compared with the traditional SMO, the new SMO of this paper designing has obvious advantages, which estimates the rotor position and speed at low speed condition more accurately.