A FPGA-based modulating scheme of digital storage combined PWM

Key words:  asymmetric regular sampling  pulse width modulation(PWM)  field programmable gate array (FPGA)  duty ratio

Abstract:

By analyzing the asymmetric regular sampling principle of pulse width modulation(PWM) , a simple method appropriate for online algorithm was provided and a FPGA-based digital method of phase-locked synchronous PWM modulator was presented. Both FPGA and ROM are used as programmable timer in the method. The switch frequency is high and fundamentally stable. The modulation ratio, phase and frequency can be controlled independentally，which is specially applicable to PWM reversible rectifier. The whole system is controlled through a piece of FPGA, thus massive analog devices are saved and the circuit board design is simplified. With such a method, the flexibility, accuracy and reliability are improved. In addition, the online programming function of FPGA facilitates the upgrading of the system. The experimental results show that the method is characterized by high response speed, strong real-timeliness and good reliability.