A simpleminded MOSFET circuit provides PWM drive for the BLDC blower:
BLDC Fan PWM Test Fixture – schematic
The Tek P6302 current probe looms much larger in real life than in the schematic:
BLDC fan PWM Test Fixture
A quick dataset shows the RPM variation against PWM duty cycle:
BLDC Blower – RPM vs PWM – doodles
Unsurprisingly, the RPM curve resembles the earlier results against a variable DC supply voltage:
BLDC Blower – RPM I P vs V
Capturing the current waveform is stalled behind another project, but it has exactly the voltage spikes you’d expect from forcibly switching an inductive load.
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