Research And Design Of PWM Generator Based On FPGA

PWM (Pulse Width Modulation) is a kind of control technology controlling analog circuit with digital signal. It is widely applied in electric power and electronic devices, such as power, electric motor, servo system, communication system, electronic controller, power control. PWM technology is the most widely applied in contravariant circuit and is also the core of frequency conversion technology. Meanwhile it also plays an important role in machine tool, hydraulic pressure location control system and other mechanisms. PWM technology has already become a bright spot on controll fields, so the study of PWM generator has a very important meaning to the development of basic theory and the improvement of technology.The main content that the paper studies is to produce the needed PWM waveform by the specially appointed method using arbitrary waveform as modulation signal, the synthesis of arbitrary waveform and the generation of PWM waveform are two main tasks. The synthesis of arbitrary waveform is one of difficulty in the design project that is one of factors influence on system performance. The way of waveform synthesis uses direct digital frequence synthesis technology to complete. DDS thchnology uses phase as address and synthesizes waveform through looking up discrete data of amplitude, and it has the advantage of continuous variational phase, high degree resolution, fast frequence conversion speed, and conveniently changing output frequence by setting control words. At present it is a mainstream way in waveform synthesis.There are many ways to design PWM generator. The paper provides a design way that uses programmable logic device (PLD) as main way and MCU as assistant and synergic way after a comprehensive comparison of common development tools's characteristic, such as MCU, DSP, ARM and so on. With the rapid development of computer technology and microelectronic technique, the integrated degree and capacity of programmable logic device are getting larger and larger, the way based on PLD is getting a mainstream way step by step and is a hot spot on the design of electronic system in recent years. The whole system is made up of three parts, the part of simulative waveform generation, MCU control circuit, function modules internal FPGA. The design of FPGA uses Quartus II software developed by corporation Altera as development platform and adopts VHDL language as main input way to complete the design entry, compiling, simulating and other debugging work. The object carrier is Cyclone II series components produced by corporation Altera that have high rate of performance and price. MCU is mainly in charge of the setting and displaying of control words, the receiving and sending of waveform data. The task of drawing and simulating arbitrary waveform is completed by MATLAB software.There are five chapters in the paper. The paper introduces the project background, development and application of PWM generator, the purpose and significance of the project in detail, discusses the feasibility of system design scheme, explains the design ways of peripheral circuit and function modules internal FPGA concretely, analyses and states simulating results, system performance, existing problems and improved ways etc. The whole design satisfies requirements of PWM generator's task and function, and the design way is feasible.