Study On Design Technology Of Variable Speed ​​Constant Frequency Device For Marine Doubly - Fed Belt

Ship shaft system can use the power reserve of ship main engine to improve ship energy efficiency, which is important for energy conservation and reduction of ship operation costs. Doubly-fed induction generator(DFIG) is easy to realize Variable-Speed Constant-Frequency(VSCF) operation, as to as independent active and reactive power regulation. DFIG has the ability of four-quadrant operation and requires smaller converter capacity(slip power). With the development of power electronics technology and motor control technology, applying DFIG in shaft system has practical significance. VSCF device that controls DFIG rotor excitation is the key equipment of DFIG shaft system. There are some theoretical research in domestic, but engineering applications are rare.This study summarized the comparison of different ship shaft systems and the status quo and development trend of domestic and international research. VSCF device of the DFIG shaft system was selected as study subject based on comparison results and development trends. Firstly, the study established a DFIG mathematical model to analyze DFIG operating principles. Then, the double PWM converter was selected as VSCF device to provide DFIG rotor AC excitation. The study established dual PWM converter mathematical model. With the foregoing mathematical model, the study built a DFIG shaft system simulation model in Simulink and simulations were carried out under different conditions to verify the mathematical model and control methods. The study analyzed a detailed needs of the VSCF device’s power circuit and controller. The power circuit and controller were designed and developed as well as the DSP control software. Finally, the study built a VSCF device test system of DFIG shaft system with small capacity. Operation tests were conducted under different conditions. Experiment results showed that the VSCF device can control the DFIG realizing VSCF operation as well as active and reactive power decoupling control which achieved the design features.