关键词: 
数字正交调制解调 /
直接频率合成 /
比例积分控制 /
数字信号处理 /
可编程逻辑门阵列

摘要:  在HIRFL加速器系统中， 需要对射频加速电压的幅度和相位进行精确控制，以实现对重离子的精确俘获、 加速和引出。传统的幅度、相位稳定控制系统采用幅度和相位两个反馈闭合环路来分别稳定腔体电压的幅度和相位。 数字化高频低电平控制系统(LLRF) 基于可编程逻辑门阵列（FPGA）和数字信号处理（DSP）， 采用直接数字频率合成（DDS）与数字正交调制解调（I/Q）技术来实现对高频功率源的控制。 相位控制精度更高， 系统更加稳定。 目前控制系统在假负载上通过了长期稳定性的实验和高功率实验， 幅度偏差小于或等于±1％， 相位偏差小于或等于±0.5°。 In order to ensure that the beam quality is well enough， we need to precisely control the frequency， amplitude and phase of cavity electric field. Traditional control system consists of amplitude loop and phase loop. And these two loops control amplitude and phase stability respectively. The digital low level radio frequency (LLRF) system， which uses advanced digital control technology， needs only one feedback loop to control amplitude and phase stability. The phase control precision and stability of the system are higher than the traditional control system. The LLRF system is based on field programmable gate array (FPGA) and digital signal processing (DSP)， and implemented by direct digital frequency synthesis (DDS) and digital orthogonal modulation and demodulation (I/Q) technology. The digital LLRF system has been tested in a longterm stability and highpower experiments. The amplitude deviation is lower than ±1%， and phase control accuracy is within ±1°.
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