Research On Control And Drive Strategy Of Wide Speed And Low-induction Brushless DC Motor For Flywheel

With the rapid development of our country's aerospace industry,the high-performance flywheel speed control system has become the focus of research and development as a common actuator for attitude control of spacecraft.Using an ironless low-induction brushless DC motor to replace the traditional motor to drive the flywheel rotor can improve the speed range,performance and e fficiency of the flywheel speed control system,and has broad development prospects.In this paper,according to the requirements of the flywheel speed control system,through the research of the drive strategy of the low-inductance brushless DC motor and the phase-locked loop of the flywheel wide speed control system,the wide speed control system of the low-induction brushless DC motor for flywheel is designed and implemented.First of all,this paper models and analyzes the research control object-flywheel speed control system.Based on the introduction of its basic structure and working principle,the flywheel speed control system is mathematically modeled with the low-inductance brushless DC motor in the system as the focus,and the simulation model of the flywheel speed control system based on Simulink is established.A theoretical analysis of the drive motor's winding current fluctuation of the flywheel speed control system is carried out,and the direction of three improved drive strategies for the low-inductance brushless DC motor is determined.Secondly,three improved driving strategies are proposed for the low-inductance brushless DC motor.On the basis of simulation analysis and verification,a new driving strategy combining various strategies' advantages is proposed.The basic principle of PWM frequency-doubling modulation strategy is explained,and simulation modeling is carried out,which proves that this strategy can obtain smaller winding current ripple and electromagnetic torque ripple.And the advantages and disadvantages of the frequency-doubling modulation strategy and its scope of application are pointed out.The driving strategy of lead angle control for add inductance is realized in the simulation model,which proves that the strategy can reduce the electromagnetic torque ripple and improve the driving performance.For the variable dc-link voltage driving strategy,the step-down chopper circuit is adopted.The parameters of the core components are determined.After the circuit principle and simulation analysis,the dual-stage step-down chopper circuit is determined.And the variable dc-link voltage strategy of the front-stage closed-loop and the backstage open-loop is determined.The feasibility of this strategy have been proved by the simulation.On the basis of the above research,a new driving strategy for low-inductance brushless DC motor is proposed.Furthermore,the flywheel wide speed control system based on phase-locked loop is modeled,designed and simulated.The mathematical model of the phase-locked control loop of the flywheel system is established,which proves that the three-type phase-locked loop system can theoretically track the rate ramp signal indefinitely.Each link are optimized,and improve the stability and dynamic performance of the system.A simulation model of the flywheel wide speed control system based on the phase-locked loop is built,and the steady speed accuracy of the system is better than 1/10000.And it has good speed tracking performance for wide-range rate ramp signals.Finally,the wide speed control system of the low-induction brushless DC motor for flywheel is designed and implemented.The basic debugging of the system is completed,which verifies the rationality and effectiveness of the adopted technica l scheme.After the circuit parameter calculation,chip selection and circuit design,the hardware circuit design of the drive system is completed.The software algorithm of FPGA-based Hall rotor position pre-estimation method and phase-locked loop control algorithm are implemented,and the correctness of the above algorithm is verified by Modelsim timing simulation and frequency characteristic simulation.The drive system debugging and experimental analysis are carried out.The two-stage closed-loop variable dc-link voltage output experiment verifies the correctness and working stability of the system.At the same time,it proves that the variable dc-link voltage driving strategy has good output characteristics and dynamic performance.