The fundamental difference is that dither is a signal added to the PWM signal to achieve specific results, particularly in applications like controlling solenoid valves.
Understanding the Relationship
Pulse Width Modulation (PWM) is a technique used to encode a message into a pulsing signal. It's commonly used to control the power supplied to devices, like motors or solenoids, by varying the width of the pulses. A wider pulse means more power is supplied over time.
Dither, as defined in the reference, is not the main signal itself, but rather:
Dither is a small ripple frequency that is superimposed over the PWM signal to the solenoid current
This means the dither signal is layered on top of the existing PWM signal that is being sent to the device (like a solenoid).
How Dither Works with PWM
When dither is added to the PWM signal controlling a solenoid valve, it creates a small, rapid oscillation or vibration. This constant, slight movement prevents the valve from sticking or experiencing static friction, especially at low signal levels.
Benefits of Adding Dither (According to the Reference)
The reference highlights the specific advantages of using dither in this context:
- Causes desired vibration.
- Increases the linearity of the valve.
- Improves valve response.
Essentially, by keeping the valve slightly agitated with dither, the control becomes smoother and more predictable across its operating range, leading to better performance.
In summary, think of PWM as the primary signal controlling the average power or position, while dither is an added helper signal that improves the performance and responsiveness of the controlled device by preventing sticking through vibration.
