Fast Square Root Calculation for Control Systems of Power Electronics

Square root calculation is a widely used task in real-time control systems especially in those, which control power electronics: motors drives, power converters, power factor correctors, etc. Meanwhile, calculation of square roots is a bottle-neck in optimization of the code execution time, therefore solution of this problem can help to accelerate a number of routines used for the control of power electronics. Taking into account that for many applications approximate calculation of a square root is enough, calculation time can be seamlessly decreased with the pay of decreased precision. This paper proposes novel method for fast square root calculation, which is based on the approximation of parabola with hyperbola. The comparison of the proposed method and Newton-Raphson, which is one of the best existing methods, is also given. It shows that proposed method is faster and provides precision of 0.25%, which is higher than two iterations of Newton-Raphson method.