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Brushed Motor Speed Equation:
The brushed motor speed equation calculates the rotational speed of a DC brushed motor accounting for the time-dependent startup behavior. It models how the speed approaches its steady-state value over time.
The calculator uses the time-dependent motor speed equation:
Where:
Explanation: The equation shows how motor speed increases from zero to its steady-state value following an exponential curve determined by the motor's time constant.
Details: Understanding the time-dependent speed profile is crucial for applications requiring precise motor control, preventing current surges, and predicting acceleration behavior.
Tips: Enter all parameters in the correct units. The time constant (τ) is typically provided in motor specifications. For steady-state speed, enter a time value much greater than τ (e.g., 5×τ).
Q1: What is the motor time constant (τ)?
A: The time it takes the motor to reach 63.2% of its final speed when a constant voltage is applied.
Q2: How accurate is this model?
A: It's a first-order approximation that works well for basic analysis but neglects factors like friction and load variations.
Q3: What affects the time constant?
A: Motor inductance, resistance, inertia, and load characteristics all influence the time constant.
Q4: Can I use this for brushless motors?
A: No, brushless motors have different operating principles and require different equations.
Q5: What if my motor never reaches the calculated speed?
A: This could indicate excessive load, incorrect parameters, or that the motor is operating outside its design limits.