Research And Implementation Of PID Controller Based On FPGA

The PID controller based on microprocessor solved the problem that the parameters cannot be changed flexibly in traditional analog PID controller. But the general microprocessorhas a limit of blind running when placed in atrocious condition. If the microprocessor whichimplements PID arithmetic breaks down for disturbance or other reasons, it will make theoutput values change a lot or stop response, while FPGA can solve the problem in essentially.So it's significant to implement intelligent technology in FPGA chip and apply them indiverse conditions.First, the internal structure of FPGA is analyzed and the FPGA design technology anddesign flow is summarized. It points out that implementing optimized structure design andlowering design difficulty is the key of extending design function and improving chipperformance and product cost performance. The control system is consisted of four modules,including kernel controller module, input module, output module and HMI module, of whichthe controller is the key part. Based on the design structure styles and characteristics of FPGA,an improved parallel structure of PID temperature controller based on PFGA is put forward.In the logic reflection process for the PID algorithm and FPGA operator, the number of logicarithmetic component can be reduced effectively by fusing different solved methods into one,such as replacing subtracter with complementary-code adder designed, extending the resultbits of the integer operation and normalizing different types of data in integer. Graphic inputof QuartusⅡand Verilog HDL language are combined to design the PID controller.Modelsim simulation validates that the result of PID controller designed on FPGA is correct.Synplify Pro is used to synthetize the design and FPGA programming file is made afterplacing and routing the design in QuartusⅡ. According to the requirements of control system,a 12-bit A/D circuit, data display, keyboard and other relating peripherals are designed.Aiming at the controlling object of furnace temperature with first-order, pure lag andgreat inertia, A PID control system is formed with EP1C3T144 as the control kernel. Underthe experimental environment with Pt100 as the temperature sensor, the resolution of 2Celsius degree and the control range in 0～400 Celsius degree, the experiment indicates thatthe PID output obtains the result of non-overshoot and stabilization, and an effective way isprovided to lower the design difficulty of PID controller on FPGA.