基于FPGA的旋转变压器CORDIC解码算法的研究

Research on CORDIC Decoding Algorithm of Resolver Based on FPGA

针对旋转变压器解码系统测量精度不高、解码周期长、占用FPGA资源多的问题,设计一种改进型流水线结构的旋转变压器CORDIC(座标旋转数字计算法)解码算法。通过分析反正切函数的特征,对旋转变压器的输出信号进行角度变换,对测量角度进行全平面扩展,将CORDIC解码算法中复杂的三角函数运算转化为一系列简单的移位和求和运算。算法以FPGA为硬件载体,采用Verilog HDL语言实现。研究结果证明,改进型的CORDIC解码算法测量精度可达1‰,动态响应小于1μs,满足电机转速测量的高精度、低延时需求,对复杂环境下的电机转速研究和应用具有重要的价值。

In order to solve these problems that the measurement accuracy of the resolver decoding system isnot high, the decoding period is long, and the FPGA resources are occupied too much, an improved coordinaterotation digital computer（ CORDIC） decoding algorithm for pipeline transformer was designed. By analyzing thecharacteristics of the arctangent function, the angle transformation was conducted for the output signal of the resolver,and all the measurement angles were extended. The complex trigonometric functions in the CORDIC decodingalgorithm were transformed into a series of simple shift and summation operations. The algorithm usesFPGA as the hardware carrier and adopts Verilog HDL language. The results show that the accuracy of improvedCORDIC decoding algorithm can achieve ／%c^ and the dynamic response is less than 1 [xs, which satisfythe demands of high precision and low delay of the motor speed measurement. It is of great value to the researchand application of the motor speed in complex environment.