| Servo control system,especially the servo system with high precision and high control performance,is widely used in various fields such as aerospace,automation,motion robot,motion control and new energy electric vehicle.At present,the main inverter of servo system adopts IGBT made of Si material.Due to the limitation of its performance,especially the research on Si material is close to its theoretical limit,so the development of servo system towards higher power density and smaller size has met a bottleneck.In the fields of industrial robots and aerospace and space station,it is an irresistible trend to develop towards higher power and smaller size,which is also an opportunity and challenge in the future.Wide bandgap materials mainly include gallium nitride(GaN)and silicon carbide(SiC),which are suitable for more powerful applications due to their greater pressure and current resistance.At the same time,the switching frequency is very high,so the volume of the driver and inverter can be reduced,which is conducive to achieving higher power density,achieving real integration of drive and control,and the efficiency of the whole system can be greatly improved.Therefore,it is of great significance to study the wide bandgap servo drive system.In this paper,a servo drive control system based on GaN wide bandgap device is built.First,the parasitic parameters of the drive circuit and power circuit based on the GaN high frequency drive system are analysed,the influence of the voltage of the crosstalk and the causes of shock are analyzed,according to the modeling analysis for the influence of parasitic capacitance and parasitic inductance of drive system.According to the parameters impact analysis the schematic and PCB design are finished,improving the GaN servo drive system of cooling way.The production of a prototype is completed.In this paper,a servo drive control system based on GaN wide bandgap device is built.Firstly,the device characteristics of GaN are analyzed,including the influence of parasitic capacitance and parasitic inductance on the driving performance.Then,from the perspective of parasitic parameters,the influence of device selection,circuit design and PCB layout on GaN drive system was analyzed in detail,and the parasitic parameters and misleading mechanism were analyzed in detail by modeling.After that,the schematic diagram and PCB design were carried out and the parasitic parameters and crosstalk were analyzed and solved in detail,which improved the heat dissipation mode of the current GaN servo drive system,completed the production of the prototype,and built the servo motor drive system based on GaN power device.Next,The mechanism and harm caused by electromagnetic interference in motor control system are analyzed,which is analyzed emphatically in the use of wide band gap materials of the motor drive system,due to the large high switch frequency and dv/dt and di/dt led to sharp electromagnetic interference phenomenon.The frequency modulation methods commonly used at present are introduced from the aspect of software suppression.Then,according to the direct digital frequency synthesis technology,the no-wait carrier continuous frequency modulation strategy adopted in this paper is proposed,the suppression effect of carrier form,spread spectrum and modulation coefficient on the EMI is analyzed,the theoretical analysis proves the superiority of the proposed frequency modulation algorithm.Finally,based on the continuous without waiting for the carrier frequency modulation algorithm to complete the parameters of the controller is designed,and through the FPGA to complete the double closed loop control of the motor.The driving performance is tested on the platform,the results show that the high switching frequency of servo drive system has excellent performance,and current loop and speed loop bandwidth has improved,EMI had obvious inhibition,drive system has excellent performance. |
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