The Research Of High Precision Three-phase Signal Source Based On FPGA

As an application of waveform generator, the power frequency signal source has been widely used in three-phase AC power supply and meter calibration device. With the development of power measurement technology, the measurement accuracy of the meter calibration device has becacme more precise, and the measurement content has become more rich. That is need a more preciser power frequency signal source in meter calibration device. The new demands for power frequency signal source are reflected in the the regulation accuracy of waveform parameters (like amplitude, frequency and phase), waveform distortion, the stability of waveform, the convenience of controlling, and the diversity of test content.The high precision three-phase power frequency signal source based on FPGA (Field Programmable Gate Array) adopt the advanced DDS technology that improved the frequency characteristics of low-frequency signal highly. In addition, It has a set of suitable implement for the modulation of amplitude, frequency and phase which meet the actual application environment and requirements. This signal source is consist of digital waveform generator part and control part. Digital waveform generator has a core of FPGA, used to generate three-phase six-way wave signal contain AC signal and DC signal. The control part has a core of MCU, used to receive control instruction and set all parameters of digital waveform generator.By study the waveform generator technology and the DDS technology, this project has designed and realized an advanced DDS system that can generate a kind of low-frequency waveform signal have high frequency accuracy and stability.This paper’s working mainly include the following:1. Introduced the effect of power frequency signal source in meter calibration device, and this project’s practical significance and importance. Introduced two kinds of methods of design waveform generator:the traditional digital waveform synthesis technology and the DDS technology.2. Designed and realized the advanced DDS system according to the current DDS system’s shortcoming in generating low-frequency waveform signal. Also designed some implement for the modulation of amplitude, frequency and phase. These implements for modulation all conformed to the actual application requirements.3. Designed and realized the PCB circuit, contain the digital waveform generator circuit based on EP3C10E144. the control circuit based on STM32F103TBT6, and power supply circuit.4. Designed and realized the logic design in FPGA. 5. Designed and realized the control program in STM32.6. By the debugging and application in meter calibration device, verified the technical indicators and practicality of this power frequency signal source. Also make a summary and prospect of this project.Finally, The completed power frequency signal source is able to achieve all of the technical indicators, especially has outstanding performance in the respect of adjust frequency. It also can receive the USART instruction of meter calibration device, generate a variety of waveform signals, and implement a variety of test control.