PWM Review
PWM Review
What is Pulse Width Modulation?
What is Pulse Width Modulation?
PWM is a scheme to represent a signal
PWM is a scheme to represent a signal
as a sequence of pulses
as a sequence of pulses
fixed carrier frequency
fixed carrier frequency
fixed pulse amplitude
fixed pulse amplitude
pulse width proportional to instantaneous
pulse width proportional to instantaneous
signal amplitude
signal amplitude
PWM energy
PWM energy
≈
≈
original signal energy
original signal energy
Differs from PAM (Pulse Amplitude
Differs from PAM (Pulse Amplitude
Modulation)
Modulation)
fixed width, variable amplitude
fixed width, variable amplitude
Pulse width modulation (PWM) is a method for representing an analog signal with a digital
approximation. The PWM signal consists of a sequence of variable width, constant amplitude
pulses which contain the same total energy as the original analog signal. This property is
valuable in digital motor control as sinusoidal current (energy) can be delivered to the motor
using PWM signals applied to the power converter. Although energy is input to the motor in
discrete packets, the mechanical inertia of the rotor acts as a smoothing filter. Dynamic motor
motion is therefore similar to having applied the sinusoidal currents directly.
7 - 4 C28x - Event Manager
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