Control Systems — question 1 of 10
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A cooling fan can be run two ways: (1) open-loop, where you just set a fixed PWM duty cycle and hope the RPM lands where you want, or (2) closed-loop, where a tachometer measures actual RPM and the controller adjusts duty cycle to hold a target RPM. As the battery voltage droops from 8.4V to 6.0V over a discharge cycle, explain what happens to the fan speed in each case and why the closed-loop version behaves differently.