Under pulse control, the motor speed is directly related to the pulse frequency. The higher the frequency, the higher the motor speed. First, let's take a look at the relationship between motor speed and pulse frequency.
Formula: Motor Speed = Pulse Frequency × 60 (coefficient) / Pulses per Revolution (Drive Resolution)
Obviously, to increase the motor speed, you can either increase the pulse frequency or reduce the pulses per revolution set in the drive. The same principle applies to servo motors under pulse control. The motor speed is related to both the pulse frequency and the pulses-per-revolution setting.
For example, suppose you use a pulse controller that works normally with a stepper system to control a servo motor. Without changing any settings, you may find that the servo motor speed has decreased significantly. This does not mean that there is a problem with the controller. Instead, it is because the pulses-per-revolution settings of stepper drives and servo drives are different.
For stepper drives, the default pulses per revolution is generally around 2,000, while the default setting for servo motors is typically 10,000, which is five times higher. For example:
If the maximum output frequency of the pulse controller is 200 kHz (200,000 Hz), the maximum motor speed that can be achieved at the maximum frequency is:
Stepper Motor: 200,000 × 60 / 2,000 = 6,000 RPM
Servo Motor: 200,000 × 60 / 10,000 = 1,200 RPM
This is why even when you turn the speed control knob on the controller all the way up, the servo motor speed may still not increase.
When encountering this situation, we recommend the following:
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First, check whether the controller's maximum output frequency is sufficient to meet the motor's rated speed requirements.
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If the motor cannot reach its rated speed, check the drive manual and find the pulses-per-revolution parameter (usually located near the beginning of the parameter list). Reduce the value as needed, then power the drive off and restart it for the parameter to take effect.