An Improved Hybrid Modulation Method for Low-Speed Control of the Servo Mechanism in Space Photoelectric Platform

Stabilized control is one of the key technologies of the space photoelectric stabilization system. The traditional six-sector space vector modulation method is widely used in the control of the servo mechanism in space photoelectric platform. The dead time inserted in this modulation method will reduce the output voltage, resulting in the phase aberration and the distortion of the motor current. The dead-time effect is particularly evident when the platform is running at low speed. In order to solve the problem, an improved modulation method for low speed control of the servo mechanism space photoelectric platform is described in this thesis. The method is a mixed modulation mode of 180 degrees and 120 degrees alternately turning on, redividing the space into twelve-sector and equalizing the amplitude of each fundamental voltage vectors. The method proposed in this thesis avoids the effect of dead-time for there is no dead-time inserted. The thesis compares the differences between the traditional six-sector modulation method and the proposed method in the aspects of principle, formula derivation, and simulation, verifies the simulation results by experimentation. The control unit of the experimental system is a digital signal processor (DSP) and a field programmable gate array (FPGA).