Dither amplitude, in the context described, refers to the magnitude of the variation in current (or voltage) applied in a dithering process, and it is a function of coil inductance and PWM frequency.
Here's a breakdown:
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Dithering: Dithering is a technique used to improve the precision or resolution of a system by adding a small amount of noise (in this case, a varying current) to the signal. This can help to overcome static friction or quantization errors.
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Dither Current Amplitude: This refers to the size or strength of the alternating current that's being added as part of the dithering process. A higher amplitude means a larger swing in current.
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Key Factors Influencing Dither Amplitude: According to the reference, dither amplitude is primarily determined by:
- Coil Inductance: The inductance of the coil used in the system (e.g., a motor coil) plays a significant role. Inductance resists changes in current, so a higher inductance will generally result in a lower dither amplitude for a given PWM signal. The inductance itself is also related to the coil's voltage and wattage ratings. Higher voltage and wattage coils often have higher inductance.
- PWM Frequency: Pulse-Width Modulation (PWM) is a common method for controlling the current supplied to a coil. The frequency of the PWM signal directly impacts the dither amplitude. Higher PWM frequencies typically result in lower dither amplitude, as the coil has less time to react to each pulse.
In simpler terms: Imagine you're trying to gently nudge a heavy object.
- Coil Inductance is like the object's weight (inertia). A heavier object (higher inductance) is harder to move (smaller dither amplitude).
- PWM Frequency is like the speed at which you're nudging. If you nudge very quickly (high PWM frequency), the object won't move much each time (smaller dither amplitude).
Example:
Consider a motor controlled by PWM. If the motor coil has high inductance and the PWM frequency is also high, the resulting dither amplitude will be small. This might be desirable in a precision positioning system where large movements are undesirable but small oscillations need to be overcome. Conversely, if the coil inductance is low and the PWM frequency is low, the dither amplitude will be larger.
In Summary: The dither amplitude is the extent of the current variation during a dithering process. It's governed by the coil's electrical properties (inductance) and the characteristics of the control signal (PWM frequency). Controlling these factors allows for fine-tuning the dithering effect.
