.BLDC.Utilities.EncoderTimeSpan

Information

Evaluates the input signals from an IncrementalEncoder:

• 0-track y[1] = 1 pulse per revolution with a length of 2*pi/(4*pRev)
• A-track y[2] = pRev pulses per revolution
• B-track y[3] = pRev pulses per revolution, displaced by 2*pi/(4*pRev)

and determines mechanical angular velocity w and mechanical angle phi:

• w = angular velocity
• phi = angle = integral of w

The time span from one edge of the input signals to the next is measured, thus calculating the speed of rotation: 2*pi/(4*pRev)/(time - t0). Taking both rising and falling edges of A-track and B-track into account, 4*pRev edges per revolution are observed. Note that the output is discrete w.r.t. to time, it is not differentiable. The algorithm depends on interrupts (which appear in Modelica as when-clauses). The direction of rotation has to be detected by a logic from the values of A-track and B-track. Note that this algorithm depends on the accuracy of the representation of time, but usually gives better results than counting edges during a time gate.