.BLDC.Utilities.SinCosEvaluation

Information

Evaluates the input signals from a SinCosResolver:

• y[1] = offset + cos(p*phi)
• y[2] = offset - cos(p*phi)
• y[3] = offset + sin(p*phi)
• y[4] = offset - sin(p*phi)

to obtain the electrical angle phi and the electrial angular velocity w:

• phi = angle (continuous)
• w = angular velocity

Subtracting the inputs pairwise y[1] - y[2] and y[3] - y[4] eliminates the offset. The results are interpreted as real and imaginary part of a space phasor. Calculating the angle of the space phasor using atan2 gives the desired rotor angle, wrapped to the interval [0, 2*p). This calculation is sensitive on amplitude errors of the input signal, and the result cannot be differentiated.

Note:

Usually the number of pole pairs p matches the number of pole pairs of the permanent magnet synchronous machine. Therefore the results directly provide the electrical rotor angle, i.e. p*phiMechancial, and the electrial angular velocity, i.e. p*wMechancial.