基于DDS的SPWM自然采样法硬件实现

Design of SPWM Natural Sampling Realization by Hardware based on DDS

提出了一种正弦脉宽调制(Sinusoidal Pulse Width Modulation,简称SPWM)自然采样法的全数字硬件实现方案。它利用直接数字合成(Direct Digital Synthesis,简称DDS)技术,产生频率稳定的三角载波和正弦调制波,经高速模拟比较器比较,其输出状态在波形交点时刻自动翻转,从而控制相应的开关器件通断,完全避免了实时计算。以三相SPWM调制电路为例,详细介绍了方案的实现原理及软硬件设计。实测结果表明了该方案的有效性。整个系统以高速微控制器为核心,可方便地实现输出频率和载波比的在线调整,采用不同外围电路,即可实现多种类型的PWM电路控制。

A new scheme of implementing the SPWM natural sampling is proposed.The strategy can produce triangular-carriers and sinusoidal modulation wave with steady frequency using the DDS devices directly.After compared with the high-speed analog comparator, the output state can reverse automatically at the time of wave intersection, thus the on/off control of the power devices can be realized,so the real-time calculation is avoided completely.Taking the threephase SPWM circuit as the example, the paper introduces the realization principle of the scheme and the hardware and the software design.The signals＇ wave showed the effect of the scheme.The system takes the high-speed micro controller as a core,and can realize the online adjustment of the output frequency and the carrier ratio conveniently.Using the different peripheral circuit, many kinds of PWM circuit control can be realized.