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142 Bu il d Y o ur O w n Q u a d c o p t e r
Figure 6.14 AR8000 100% throttle channel output.
was observed spinning at a very high rate, and the power pulses from the ESC to the motor
were very evident, as shown in Figure 6.15.
This 100% power-pulse waveform is remarkably clear with just a few switching transient
pulses obvious in the waveform. You can easily view the up and down ramps that are on
either side of the power pulse. I discussed how ramping was configured in the last chapter’s
ESC section but not why it is needed. Ramping is required to allow sufficient time for the
electromagnetic (EM) fields located at the stator poles to both build and decay. A synchronized
rotating EM field cannot be established and maintained without allowing enough transition
time, which is the reason for the ramps.
Figure 6.15 ESC motor waveform at 100% power.
