Optimization Of Reactive Power Compensation On Contactless Excitation Energy Coupling Transmission System

At present,brush and sliding ring are widely used in synchronous motors to supply power to excitation windings.The traditional contact excitation method has the potential risk of wiring aging.Moreover,the friction between the brush and the sliding ring will produce metal scraps,which may lead to the reduction of the electric insulation property of the synchronous motors.Because of its safety,reliability and flexibility,inductively coupled power transmission technology(ICPT)has attracted considerable attention of researchers all over the world.The application of ICPT technology in the excitation of synchronous motors using air gap for energy transfer can make up for the shortcomings of traditional excitation methods.For improving the power transfer capability of the ICPT system,there are some common methods,e.g.,increasing the working frequency or transmission power of the primary side;improving the quality factor of the resonant circuit or coupled coefficient of ICPT system.Meanwhile,more and more electrical devices will adopt this contactless power supply in the future along with the advancement of ICPT technology.So people will not only pay attention to the high quality and reliability of ICPT,but also focus on its power and efficiency issues.ICPT system is the core of contactless power transfer.This dissertation analyzed the transmission power and efficiency of ICPT system with primary-secondary side series compensation,and analyzed the influence of the detuning factor and coupling factor on the energy efficiency of the ICPT system.A method to realize the parameter design of ICPT system by using the detuningfactor was proposed,that is,detuning factor correction method.The detuning factor correction method considers the inconsistent distribution of power and efficiency when the inductively coupled power transmission system is over-coupling,and avoids the phenomenon that the power and efficiency cannot be well matched.The MATLAB simulink model was established to verify the overall performance of the maximum power ratio and efficiency with different methods.The simulation results showed the proposed method could maintain the stability of the power and efficiency of the ICPT system when the resistance-capacitance or resistance-inductance load changed.In order to visually verify that the detuning factor correction method was superior to other methods.The magnetic field simulation model of transformer was established by Ansoft and the leakage flux density distribution and the current density distribution of the windings by detuning factor correction method and the other three mainstream methods were obtained.It was found that detuning factor correction method had the lower magnetic flux leakage density and the higher current density.The correctness of detuning factor correction method from the perspective of magnetic field was verified again.Finally,the experimental platform of the contactless excitation system was built.The output voltage of the synchronous motors was tested at different speeds,and the output characteristics of the system were analyzed experimentally.It showed that the proposed method could guarantee the transmission ability of the excitation and realize reliable excitation of synchronous motors.