设计了一款片上正弦脉冲宽度调制(sinusoidal pulse width modulation,SPWM)控制器,提出一种基于调制波周期归一化的SPWM实现方法.以正弦调制波周期T为基准,三角载波的周期为T/n(取n=10),考虑到通用性,所给出的设计方案是在对正弦调制波周期T作归一化的条件下,离线解一组三角载波与正弦调制波的联立方程组,计算出它们的交点(即SPWM脉宽开关点)相对时点值,通过移位寄存器、加法器及相关算法实现输出波形在交点相对时点值处翻转,得到一定载波比下的SPWM波;同时此控制器也通过捕获外部信号的周期,输出经过变频后的SPWM波;对已嵌入此SPWM模块的SHU-MV08a进行验证,并在ModelSim上通过了寄存器传输级(register-transfer level,RTL)功能的仿真验证;最后,在FPGA开发板及所搭建的测试系统上进一步验证了其功能.实验结果表明,该设计具有实际可操作性,且可用于任意调制波.
A sinusoidal pulse width modulation(SPWM) controller based on modulation wave cycle normalization is designed.The controller can operate in two modes:user defined and captured frequency scaling.Let T be the period of sinusoidal modulation wave,and T/n(n=10) the cycle of triangular carrier.The relative time value of SPWM wave on-off switching points are first calculated off-line.A shift register and adder are used to translate these data to control the level trigger moment of the SPWM wave.The scaling frequency SPWM signal for external signal can be realized with the SPWM module used.With the SPWM controller integrated in SHU-MV08a,register-transfer level(RTL) function simulation verification by ModelSim,and testing for printed circuit board(PCB) testing system have been achieved.The results show that the proposed SPWM controller is reliable,with practical significance.The modulation wave cycle normalization based on sinusoidal wave can also be used for any modulation wave.