Study On Electromagnetic Compatibility Of Driver Circuit For Attitude Control Flywheel

The attitude control flywheel is the main implementing component of spacecraft attitude control. To provide precise control of torque, the operation of aircraft requires that the attitude control system has high accuracy. This can be fulfilled through the electronic circuit system. Be based on the need of Electromagnetic Compatibility for flywheel electronic control system, the study mainly centers on the several important issues of EMC design to launch.1) The main conducted interference source and coupling path are analyzed in the flywheel electronic control system. The frequency range of conducted interference is calculated. The common mode and differential mode power line filter parameters are designed. The effect of the filter installation is discussed.2) The crosstalk tested structure between coupled microstrip lines is setted up. The dependence between the crosstalk and the stripe protection parameters is examined. The original stripe protection structure has been improved. The simulation and experimental results indicate that |S31| peak attenuation is over 9dB compared with no strip protection, |S41| peak attenuation is more than 7dB by using the improved structure. For 5MHz~6GHz, the simulation results show that |S31| and |S41| have the same trends with low frequency ( < 500MHz) when there is no resonance. Before 5GHz, using the strip protection which has increased width can suppress crosstalk effectively. 3) The energy coupling and the radiation emission mechanism between the chip and the radiator is analyzed. The numerical model of heatsink is created. The key factor is analyzed which is related to restrict the main radiation direction of the heatsink. The method of suppressing the heatsink Electromagnetic Interfenernce is proposed and it is validated by numerical simulation. In order to meet the high EMI suppression performance and lightweight requirements, the proposed model has been further improved. The results show that the EMI suppression of the improved structure is better than the original shield plate model.4) The numerical model of enclosure with slot containing a PCB is given. The influence of different apertures size、board size and position on shielding effectiveness is analyzed. Variation regularity of induced current which is resulting from interaction between microstrip line and EMI signal is studied. The results show that using the circular slot and increasing PCB board size can effectively increase the shielding effectiveness. Electromagnetic field inside the cavity will produce induced current on the microstrip line. The longer the trace and the closer from the gap, the greater the induced current will become, and its peak value appears in the resonant cavity frequency.Through the study above, the work including the crosstalk suppression、the EMI suppression of heatsink and improvability of the shielding effectiveness have been fulfilled.