17-12-2012, 05:59 PM
Pulse-width modulation
1Pulse-width.pdf (Size: 30.57 KB / Downloads: 275)
Pulse-width modulation (PWM), as it applies to motor
control, is a way of delivering energy through a
succession of pulses rather than a continuously
varying (analog) signal. By increasing or decreasing pulse
width, the controller regulates energy flow to the motor
shaft. The motor’s own inductance acts like a filter, storing
energy during the “on” cycle while releasing it at a rate
corresponding to the input or reference signal. In other
words, energy flows into the load not so much the
switching frequency, but at the reference frequency.
PWM is somewhat like pushing a playground-style
merry-go-round. The energy of each push is stored in the
inertia of the heavy platform, which accelerates gradually
with harder, more frequent, or longer-lasting pushes. The
riders receive the kinetic energy in a very different manner
than how it’s applied.