- drive PWM speed adjustment

Frequency n = 60 f/p
n is speed; F is the frequency; P is a logarithmic machine
duty ratio refers to the power switch on state (Pulse width)And the ratio of each pulse cycle, t/t = & delta;
t is what you call pulse width (Pulse width), this way of modulation collectively: pulse width modulation
if refers to the frequency of the pulse frequency f = 1 / T
to conclude: frequency f = duty ratio & delta; / pulse width t
duty ratio is 0Speed is 0-100%The highest speed
may be 10 -90% of the range