Design Of The Digital Rectifier Controller Based On FPGA

Silicon Controlled Rectifier is a high-power semiconductor device which has switching action. It is widely used in the large capacity of rectifier system. Traditional Silicon Controlled Rectifier system provides trigger pulse for Silicon Controlled Rectifier using analog trigger controller. However, it has poor anti-interference performance and its control accuracy is not high enough. As the rapid development of digital electronic technology, the combination of integrated circuit and digital control technology shows its powerful role in more and more applications. Field-Programmable Gate Array(FPGA) appears as a semi-custom circuit in the field of application specific integrated circuit(ASIC). It has many advantages, for example, high speed, low power consumption, economical, easy to achieve precise control, easy to develop and upgrade. Digital trigger controller designed with FPGA as the core not only achieves rapid response and accurate control, but also supports remote monitoring. Thus it has more advantages than analog trigger controller. This research is on the basis of the bridge rectifying circuit composed of silicon controlled rectifier, which respectively presents hardware circuit of digital rectifier controller based on FPGA and the design of the internal control logic of FPGA. It completes the design of digital rectifier controller.This thesis is divided into the following three parts in accordance with the transition order from hardware to software.The first part mainly introduces the construction of the rectifier system hardware circuit. Firstly, this part simply introduces the working principle and working characteristic of the silicon controlled rectifier and three-phase fully-controlled bridge rectifying circuit, and the selection scheme of the core control device. Based on above analysis and combined with the specific functional requirements, it gives the overall framework of hardware circuit of digital trigger controller designed with the FPGA as the core control device. And then it respectively introduces the design plan of AD sampling circuit, phase discriminator circuit, pulse driving circuit, power supply, ARM communication module and other important sub-modules in detail.The second part mainly describes the design of FPGA’s internal control logic. This part firstly gives the overall design plan of FPGA’s internal control logic based on previous hardware circuit construction and specific functional division. Then it respectively introduces the VHDL realization of the main control module, A/D data reading module, phase pulse processing module, PWM module, UART module and EPROM reading and writing control module.The third part mainly introduces the FPGA implementation of PID control algorithm. Firstly, this part carries on the simple introduction about the core of the theory and computational method of analog PID algorithm and digital PID algorithm. Then combined with the specific requirements, it presents the design of PID control in stages. The FPGA implementation of increment PID algorithm is described in detail. Finally, through the simulation experiments of the PID algorithm under certain conditions, it verifies the feasibility of joining the PID module in the control logic.Besides having the ability of rectifying the three-phase alternating current used in industry in real time and high accurately, digital rectifier controller introduced in this thesis also has the ability of remote control and network communication. It not only meets the basic control requirement, but also greatly improves the expandability of the rectifier system.