应用于数字DC-DC转换器的高分辨率数字脉宽调制器设计

High Resolution Digital Pulse Width Modulation Design for Digital DC-DC Converter

数字控制在电力电子领域的优势使得数字脉冲宽度调制的使用日益增加,然而其分辨率不足一直是制约开关电源领域中数字控制技术发展的主要因素之一。针对高分辨率数字脉冲宽度调制的应用需求,该文提出一种基于高速进位链结构的高分辨率数字脉冲宽度调制电路。该电路采用计数器、比较器、固定相移锁相环单元及高速进位链的混合结构,有效地提高了分辨率,并在Altera的Cyclone Ⅳ低成本现场可编程门阵列器件上实现。实验结果显示,当输入参考时钟工作频率为70 MHz时,该结构的分辨率可达到56 ps。此外,该电路还具有较宽的开关频率调节范围及较好的线性度等优点。

The advantages of digital control in the field of power electronics lead to an increasing use of Digital Pulse Width Modulation(DPWM). However, the insufficient resolution of DPWM is one of the main factors that constrain the development of digital control technology in the field of switch mode power supplies. For the application requirements of high-resolution DPWM, this paper proposes a high-resolution DPWM circuit based on high-speed carry chain structure. The circuit comprises of counters, comparators, fixed phase shift PLL units and high-speed carry chains, which can effectively increase resolution. The circuit is also implemented on Altera’s Cyclone Ⅳ low-cost Field-Programmable Gate Array(FPGA) devices. The experimental results show that the resolution of the structure can reach 56 ps with 70 MHz input reference clock. In addition, the circuit also has wide switching frequency adjustment range and good linearity.