Study On Starting Control Of Wound Rotor Synchronous Starter Generator With LC Filter

The wound rotor synchronous starter generator has the advantages of brushless structure,simple power generation control,and easy and reliable demagnetization in short-circuit fault conditions,which have been widely used in aircraft power systems.The starting/power generation integration has become the development trend of aviation variable frequency ac power supply system.The research and application of the wound rotor synchronous starter generator power generation technology has been relatively mature,but there are still many problems in the starting technology that need to be researched and broken.Aiming at the problem of high-frequency harmonic current during the starting stage of a wound rotor synchronous starter generator,this paper studies a wound rotor synchronous starter generator starting system based on an LC filter.This paper first introduces the wound rotor synchronous starter generator topology and the mathematical model of the main motor,and elaborates in detail the starting and generating principles of the wound rotor synchronous starter generator.In order to ensure that the engine ignition requirements are met during the starting phase,a rotor magnetic field-oriented control strategy based on i_d=0 is selected and a simulation analysis is performed.It is found that there are problems with large three-phase armature current ripple amplitude and high harmonic content.Based on this,the armature inductance characteristics of a 90k VA wound rotor synchronous starter generator are analyzed.Secondly,the derivation mechanism of current ripple in SVPWM modulation mode is deduced,and the current ripple generated by different modulation modes is compared and analyzed,which provides a theoretical basis for the selection of the optimal modulation strategy.The mathematical model of the current ripple of the motor drive system is established,and the calculation formula of the maximum value of the current ripple and the distribution rule of the harmonic current under different operating conditions are derived,which provides an effective theoretical reference for the design of the filter in the motor drive system.Thirdly,the scheme of adding an LC filter between the inverter output side and the motor stator is used to suppress high-frequency harmonic currents,taking into account current ripple,inductor voltage drop,filter capacitor impedance,reactive power,and high-frequency harmonic attenuation.Factors such as effects,design reasonable filter parameters and carry out experimental verification.The test results show that the filter has a good suppression effect on high-frequency harmonics,and proves the correctness of parameter selection.Then,for the wound rotor synchronous starter generator starting system with high operating current and high starting frequency,the inductor body is optimized to ensure that its inductance is not saturated during the start-up process and the minimum edge flux is generated.The inductor is optimized from the core material and shape,air gap parameters,core cross-sectional area,and core inner and outer diameter ratio.Finally,the designed inductor is simulated and analyzed to verify the correctness of the design.Finally,the wound rotor synchronous starter generator starting experimental platform was set up,and a related starting program for the hardware platform based on the TMS320F28335 main control chip was written.The start-up experiment verification was carried out,and the test results proved the feasibility of the control strategy and software algorithm design.During the starting process,the harmonic content of the three-phase current waveform is small and the waveform sine is high.The harmonic content can meet the IEEE519 standard,which confirms the correctness of the research content in this paper.