Investigation Of Loss And Efficiency Existed In Motor Drive System Based On Gallium Nitride(GaN)

Motor drive systems are widely used in automation,aerospace and other fields,which are developing rapidly along the development trend of intelligence,high power density and high reliability.As the core component of motor drive system,the performance of power switching device directly affects the operation effect of the system.With the continuous development of semiconductor technology,gallium nitride(GaN)-based power devices have excellent switching characteristics and high-frequency performance.Compared with traditional silicon(Si)-based power devices,GaN materials have outstanding advantages such as wider forbidden band and faster electron saturation migration.However,due to the unique material and structure of GaN power devices,the losses and driving efficiency in the switching process are also different from those of traditional power devices.Therefore,it is important to analyze the losses and optimize the control strategy to improve the driving efficiency in order to solve the key problems that restrict the application of GaN power devices in motor drive systems.The main research work of this paper is as follows.(1)Analysing the characteristic differences between GaN power devices and silicon devices.The electrical characteristics and parameters of eGaN HEMTs are analyzed to design a driver circuit that can meet the design requirements based on their structural characteristics;the difference in characteristics is analyzed by comparing them with Si MOSFETs;the effect of circuit parameters on switching characteristics is quantified by designing a double-pulse test experiment to provide a basis for the design of high-speed driver circuits.(2)Establishing a behavioral model for GaN-based devices.This paper proposes a model for the switching behavior of eGaN HEMTs,which can accurately reflect the effects of each parameter of the switching process on the switching process and losses.The model is compared with the actual waveforms measured by double-pulse experiments to check the effectiveness of the model in reflecting the changes of each electrical parameter in the switching process of GaN HEMTs.(3)Analysing the effect of control strategies on motor drive losses and optimize the drive efficiency.According to the switching characteristics of eGaN HEMT,the impact of several control strategies on the driving loss and efficiency is analyzed by comparing with Si-based driving circuits.Focusing on the unique reverse conduction characteristics of the eGaN HEMT,the renewal method of GaN-based high-frequency full-bridge circuit is analyzed.This paper analyzes the influence of parasitic parameters in the drive circuit on the drive system according to the established behavioral model,designs a full-bridge motor driver circuit suitable for GaN power devices,combines simulation and experimental results,analysising the influence of different control strategies on the driver loss and efficiency,and clarifies the advantages and disadvantages of different renewal methods and the applicable occasions from the perspective of loss and efficiency.The model proposed in this paper can accurately reflect the changing trend of GaN HEMT in the switching process and the losses.The research of GaN-based motor driver control strategy shows that the use of synchronous rectification mode can reduce the losses of the driver and can most effectively improve the efficiency of the converter.The results of this paper give guidance to eGaN HEMT circuit design and lay the foundation for the subsequent application research of GaN-based high-frequency motor drivers.