Abstract:

Field programmable gate array (FPGA) is widely used in smart grid related relay protection and automation equipment for its flexibility, reliability and integration. Due to the prominent contradiction between the calculation accuracy and the storage capacity, the commonly used table lookup method has no advantage in calculating the cosine function discrete value in the FPGA chip which has limited storage space. Therefore, an algorithm which combines the table lookup with the Lagrange interpolation is proposed. Combining the advantages of the two algorithms, the output delay and resource consumption of the algorithm are optimized on the premise of ensuring the accuracy. The design of the algorithm and hardware verification is completed on Xilinx’s Artix7 chip.

Key words:

FPGA, cosine function, discrete value, table lookup, Lagrange interpolation