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Main Advantages of Stepper Drive

A simple way to select a stepper drive is to consider four factors: voltage, current, micro-stepping, and maximum step pulse rate. Test the system at different voltage levels to ensure that it can handle a wide range of currents. The driver should output at least 1.4 times the motor's rated current. Select a driver that has several step resolutions to test different micro-stepping settings to obtain the smoothest motion. Finally, ensure that the driver receives sufficient step pulses to rotate your motor at the desired speed. There are times when drivers are limited to a relatively low frequency, such as 10 kHz. If you're hoping to micro-step even at 8× with a 1.8° stepper, your maximum revolutions per sec speed is 10,000/ (8 × 200) = 6.25 reps. In micro-stepping, a system can be made more precise, resulting in smoother rotation and reduced noise and vibration. 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. Many users wonder why they should apply higher voltages to a motor with a rated voltage of 5 V, for example. Some them are also wondering why they are not experiencing an increase in performance after switching to a PWM/chopper drive. When engineers design stepper motors and drives, they sometimes fail to consider motor fundamentals such as back EMF and electrical time constants. This results in an incorrectly configured stepper motor drive or driver and motor starved for power (voltage or current) in the application. A number of issues can arise when an engineer fails to understand the purpose of micro-stepping. The main purpose is to increase the smoothness of motor operation by leveling out the shocks of stepping, making the operation more reliable. By misapplying micro-stepping, you can greatly decrease the available torque that the motor can produce. This usually requires a much larger motor than is otherwise necessary. Those who are unfamiliar with micro-stepping choose to avoid it, instead turning to servo-based systems, which are more complex and expensive than micro-stepping. Engineers also sometimes complete mechanical designs and then attempt to hide or dampen system vibration. When an engineer chooses an incorrect stepper, the motor won't be able to move the load weight. Select the motor while considering not only load weight but also the mechanism's frictional properties. Stepper drives offer the most cost effective solution, so use them whenever possible. Consider the following major factors: First, does the system require confirmation of position? In addition, the wrong stepper drive may cause ringing, resonance, and poor low-speed performance. Third, at high speeds, stepper motors can whine. The high pole count of stepper drives contributes to hysteresis and eddy current losses at high speeds; for these reasons, stepper drives are not recommended for continuous operation above 2,000 revolutions per minute. Finally, because the full current is needed to produce holding torque, step motors can get hot at a standstill.