Speed Measurement - Renesas RA6T2 Application Note

RA6T2
Vector control for permanent magnetic synchronous motor with encoder - AB incremental type encoder

3.1.7 Speed Measurement

3.1.7.1 Speed calculation using encoder at low speed
The sample software calculates the speed from the encoder count (A, B phase signal edge) intervals for
higher real-time and slow speed resolution. The speed is calculated from the count between the rising and
falling edges of the A and B phases as shown in the figure.
Phase-A
Encoder Signal
Phase-B
Encoder Signal
Timer Counter
Motor Rotation Speed[rad/s] = (
R01AN6208EJ0101 Rev.1.01
Oct 18, 2022
2π/Pulses per Rotation
Capture Capture
Count Per Rotation
Figure 3-7 Speed calculation using encoder at low speed
2π/Pulses per Rotation
Capture Capture Capture
2π
) / (
Timer Clock Frequency
Counter
Difference
Capture Capture
Counter Difference
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)