基于CORDIC算法在现场可编程门阵列中正余弦运算的优化实现

Optimum Realization of Sine and Cosine Calculation in the Field-programmable Gate Array Based on CORDIC Algorithm

针对变流器的控制器设计中正余弦运算过度占用控制芯片存储空间的问题,提出了一种改进的基于坐标旋转数字计算(CORDIC)算法在现场可编程门阵列(FPGA)中正余弦运算的优化实现方法。方法中将CORDIC算法的旋转角度由0~360°缩减为0~90°,取消了反正切查找表,大大降低了系统的迭代级数,并且通过将迭代缓存值的数据宽度拓宽一位,取消了原有方法中移位相加的溢出保护电路。Simulink仿真与现场可编程门阵列(FPGA)试验结果表明,方法不占用芯片存储资源,进一步降低了对芯片逻辑资源的占用,同时还提高了算法的运算速度,并具有较高的运算精度。

In order to solve the problem of overconsumption of memory space of control chips by the sine and cosine operation in the design of converter＇s controller,an optimum realization scheme was presented for the sine cosine calculation in the field-programmable gate array（ FPGA） based on the coordinate rotation digital calculation（ CORDIC）. The proposed scheme greatly reduced iteration series of the system by bringing the rotation angle of CORDIC algorithm from 0 ~360° down to 0 ~90° and abolishing the arc tangent lookuptable. Furthermore,the data width of the iteration cache value was broadened by one bit to remove the overflow protection circuit of shifting and adding operation in the former approach. Results of Simulink simulation and FPGA tests indicated that the proposed scheme did not occupy chip storage resources,thus further reducing occupation of chip logic resources. In the meantime,it raised the operation speed of the algorithm and achieved a high operation accuracy.