Fpga-based Frequency Control System Design And Realization

Today the control circuit of power electronics is to realize computer control of high frequency switches. It is developed in the direction of higher frequency,lower consumption and full digitalization. FPGA(Field Programmable Gate Arrays) is a new type of IC(Integrated Circuit) in recent years. It has advantages of compactness,economy,high speed,low consumption,full integration and good applicability. It is easy to be developed and be maintained. FPGA has higher frequency and faster speed in comparison with MCU and DSP. These advantages conform to the need of power electronics'control circuits developing in the direction of high frequency and complication increasingly. So this type of apparatus was developed and applied in more and more fields.The paper introduces the design of digital variable-frequency induction motor speed modulation control systems, based on FPGA. The system can generate three-phase SPWM pulses and has following characters: the range of modulation frequency is from 0 khz to 4 khz. and can be divided to 7 classes to control. The carrier frequency may be selected up to 24 khz, and can be divided to 8 classes to control; Rotational frequency is defined to 16 bits. The interface of system can be compatible with the Intel and Motorola MCU. And the system is easy to be controlled and be changed parameter setting during the work. PWM output pulses can be tailored to the inverter characteristics by defining minimum allowable pulse width and the pulse delay time without the need of external circuitry. To ensure a robust solution, a trip input allows the PWM outputs to be shut down immediately. The realization of the project was discussed in detail, including the analysis of the main theories; the design of system structure and realization of system on FPGA , and finally demonstrate the validity and feasibility of system.Digital design is the main character of this system. The three-phase SPWM pulses are generated through sine wave compared with triangular wave. During design, we make use of a changed structure of NCO(Numerically Controlled Oscillator) to...