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Topic: Stepper Motor Driver Basic (Read 599 times) previous topic - next topic

longlongagoo

How to choose a stepper motor driver is often asked. So I summarized some common elements and analysis, I hope it can be helpful.

Four key parameters
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Choose a stepper driver to focus on 4 parameters - voltage, current, microsteps, and maximum step pulse rate. Ensure that the driver can handle a wide range of current so that you can test the system with different motors to fit your application. The driver should output at least 1.4 times the motor's rated current. The wide range of input voltage is to ensure and improve the output torque of the motor. The disadvantage is that high voltage will also increase the motor heat. The higher the driver input voltage, the higher the motor output torque. Choose a driver that has several step resolutions to test different microsteps settings to get the smoothest motion. Finally, make sure the driver can receive enough step pulses to rotate your motor at the desired speed. I take motiongoo stepper driver as an example, the highest input pulse is 200 KHz. If you're hoping to microsteps even at 20× with a 1.8° stepper motor, your maximum revolutions per sec speed is 200,000/(20 × 200) = 50rps.

Microsteps Principle
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Microsteps can increase the resolution of a system, which smoothness rotation and prevents vibration and noise. However, problems will arise if incorrect voltage is applied to a PWM (pulse width modulation) or chopper drive. We receive many questions about these drivers. For example, if a motor is rated at 5V, many users wonder why they need to apply larger voltages. They also wonder why they are not getting increased performance even after changing to a PWM/chopper drive. Engineers sometimes forget about motor fundamentals like back EMF and electrical time constants when they are using stepper motors and drives. This results in an incorrectly configured stepper motor drive or driver and motor, which are starved for power (voltage and/or current) in the application.

Microsteps Effect
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The main purpose is to increase smoothness of the motor operation by leveling out the shocks of stepping, making the operation more reliable. If the microsteps is applied incorrectly, the available torque of the motor may be greatly reduced. This leads to the replacement of larger motors and increases costs. The engineers who do not understand the proper use of microsteps usually don't choose useing microsteps, but instead switch to a servo motor, which also adds unnecessary complexity and cost. Engineers sometimes complete mechanical designs and then try to hide or dampen system vibration. If the engineer chooses a wrong stepper, the motor will not be able to move the load weight. When choosing a motor, not only must the load weight be considered, but also the frictional performance of the mechanism.

Stepper Driver Selection
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Stepper drivers always provide the cheapest solution, so use steppers solution wherever appropriate. Keep in mind the following main considerations: First, whether the system needs location confirmation. Second, The wrong stepper driver can cause ringing, resonance, and poor low-speed performance. Third, during high speeds, stepper motors will buzz. Because stepper drivers have high pole count, hysteresis and eddy current losses are also common at high speed; for these reasons, a stepper is not recommended for continuous operation above 2,000 rpm. Finally, because full current is needed to produce holding torque, the stepper motor may become hot when standstill. I have used this driver, which has the function that half the current when standstill, this can reduces the heat generated when the motor is stopped.

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