Enter your Supply Voltage, Motor Rated Voltage, Armature Resistance, Desired Speed, and a few other motor parameters to find the exact PWM Duty Cycle needed to hit your target RPM — plus your Effective Motor Voltage, Motor Current, Power Consumption, and Estimated Motor Speed all in one shot.
PWM Duty Cycle
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Effective Motor Voltage
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Motor Current
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Power Consumption
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Estimated Motor Speed
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PWM (Pulse Width Modulation) duty cycle is the percentage of time the voltage is applied to the motor during each switching cycle. A 50% duty cycle means the motor receives power half the time, effectively reducing the average voltage and thus the motor speed.
Calculated values are estimates based on ideal conditions. Real-world factors like motor temperature, bearing friction, magnetic field variations, and manufacturing tolerances can cause measured values to differ by 10-20% from calculations.
Higher frequencies (10-20kHz) reduce motor noise and heat but increase switching losses in the controller. Lower frequencies (500Hz-2kHz) are more efficient but may cause audible noise. Most DC motors work well with 1-5kHz PWM frequency.
Even with PWM, the peak voltage should not exceed the motor's rated voltage significantly. While the average voltage may be lower, voltage spikes can damage motor windings and reduce motor life.
Higher load torque requires more current to maintain speed. The motor will draw additional current to overcome the increased load, which may reduce speed if the power supply cannot provide sufficient current.
This calculator is primarily designed for brushed DC motors. Brushless DC motors require more complex control algorithms and three-phase PWM control, making their speed control calculations significantly different.
Always use appropriate fuses rated at 150-200% of calculated running current, ensure adequate heat dissipation for the motor controller, and implement overcurrent protection to prevent damage during motor stall conditions.