Design Of The Drive Servo System Of Variable Speed Scanning Antenna

Microwave radiometers have played an important role in earth detection,atmospheric environment monitoring,meteorological system monitoring and meteorological disaster warning.To achieve more precise control of the microwave radiometer antenna scanning drive servo system,it is beneficial to obtain higher resolution images from meteorological satellites,so as to achieve more accurate detection and observation of the atmospheric environment or the earth’s surface.Therefore,the antenna scanning drive servo system It has always been a hot research topic in the field of microwave radiometers.In this paper,the surface-mounted permanent magnet synchronous motor（PMSM）is taken as the key research object,and the research contents are as follows:First of all,because the PMSM rotates to drive the antenna to scan,a vector control strategy is introduced into the PMSM control method.Through coordinate system transformation,mathematical model of the motor,space vector pulse width modulation（S VPWM）and PI control,a current loop,speed The three closed-loop vector control system of the loop and the position loop provides a theoretical framework for the subsequent construction of the antenna scanning drive servo system.Secondly,under the condition of limited power supply in space,when the switching device is controlled by the conventional SVPWM control strategy,the switching device has switching actions in the sectors with large load current or small load current,resulting in high switching frequency and large switching current,which increases the problem of switching loss of switching components.This paper adopts the minimum switching loss SVPWM control strategy to solve this problem.The control strategy adopts the method of continuously adjusting the position of the unswitched sector of the switching device according to the change of the load power factor angle,so that the unswitched sector is located in the area with large load current as much as possible,so as to reduce the switching loss of the switching device,thereby reducing the The power consumption of the antenna scanning drive servo system.The simulation results show that the minimum switching loss SVPWM technology can effectively reduce the influence of the switching current on the switching loss.Then,under the condition of the nonlinear control of the antenna in this design,the control requirements of the antenna need to achieve a fast speed response and a small overshoot,so as to adapt to the "variable speed" working mode of the microwave radiometer.In the PMSM vector control strategy,because the conventional PI controller is prone to large speed overshoot and slow speed response,the PI parameters are not easy to change after tuning,and it is not suitable for nonlinear control situations.A fuzzy self-tuning parameter is designed.PI controllers solve this problem.The simulation results show that the controller can effectively reduce the transition time and overshoot of the antenna scanning drive servo control system in the constant and variable speed scanning stages of the motor,and improve the stability of the control system.Finally,based on the functional objectives of the control system,the overall block diagram of the hardware circuit is drawn,and the circuit and software program of the antenna scanning drive servo control system are designed around the STM32 main control unit;the system experiment environment is built and experiments are carried out.By comparing the motor speed waveforms in the constant-speed scanning and variable-speed scanning modes,it is verified that the antenna scanning drive servo control system under the action of parameter self-tuning fuzzy PI control has smaller rotational speed overshoot and shorter transition time than conventional control methods.The waveform quality is better.The experimental results basically achieved the expected goal and verified the correctness of the designed antenna scanning drive servo system.