Research On Excitation System Of Electrically Excited Synchronous Motor Based On Resolver

New energy vehicles are the development direction of the automotive industry,and the operating performance of their internal onboard motors has very important impacts on the stable operation of new energy vehicles.AC motors have the advantages of adjustable excitation,but their internal brushes and slip rings will affect the performance and life of the motor.In order to replace the adverse effects of brushes and slip rings in traditional AC motors on the motors,the brushless of vehicle-mounted drive motors has become a topic of widespread concern.However,the current brushless solution needs to add additional devices or additional windings in the motor,which complicates the structure of the motor,increases the volume,and reduces the power density of the motor.Aiming at the problem of brushless excitation of AC motors,this thesis adopts the principle of non-contact energy transmission,and uses loosely coupled resolvers to achieve energy transfer to perform brushless excitation of onboard motors.The device has a wide range of applications,which can be applied to both electric excitation motors and hybrid excitation motors.The main research contents of this thesis are summarized as follows:(1)Firstly,this thesis discusses the principle and characteristics of the non-contact energy transmission system,combined with the structure and characteristics of the loosely coupled tank resolver,establishes an equivalent circuit model and an equivalent magnetic circuit model,and introduces the relationship between the transformer coupling coefficient and the transmission efficiency.The influence of the parameters of the tank resolver on the self-inductance and mutual inductance of the transformer windings was explored,and the resolver structure was improved on the basis of the resolver theory,and makes it have a higher coupling coefficient and transmission efficiency no matter the air gap is small or the variation range of air gap is large.(2)Secondly,a new type of tank resolver structure is proposed.The new type of tank resolver structure changes the inner thickness of the tank resolver,increases the number of turns on the primary and secondary sides,and thereby improves the transmission efficiency.The electromagnetic simulations of the 2D and 3D model of the tank type resolver are carried out.Through the 3D simulation,the magnetic field distribution of the initial structure and improved structure of the tank resolver is obtained,and the coupling coefficients of the two structures under different air gap conditions are obtained.Through 2D simulation,the distributions of magnetic flux density and magnetic flux line for two structures are obtained when the air gap is different,which verifies the correctness of the theory.(3)Then,the circuit design and simulation of the initial structure and improved structure of the tank resolver are carried out.In view of the large magnetic leakage of the loosely coupled resolver compared to the tightly coupled electromagnetic device,the system is compensated for resonance,and the correctness of the theoretical research and electromagnetic simulation is verified by comparing the output waveform of the resolver before and after the improvement of the control system simulation.(4)Finally,the prototypes of the initial and improved tank resolvers were manufactured.The corresponding experimental platforms were built.On this basis,a comparative experiment was conducted on the output waveforms of the resolver before and after the improvement,and the feasibility of the scheme was verified.