Comparing closed-loop and open-loop stepper systems

Recently, I got the chance to work with Eric Rice and Jeff Kordick at OYOSTEPPER Products on a technical feature detailing new technologies making step motor systems even faster, quieter, and more energy-efficient than ever before.

Step motor systems have come a long way from the early days of voltage drives and full stepping. First came PWM drives and microstepping and then digital signal processors (DSPs) and anti-resonance algorithms. Now, closed-loop stepper designs could become the new cornerstone of the motion control industry. One such closed-loop system implements on an integrated motor design that includes a feedback device, driver and controller boards, power, communication and I/O electronics, and system connectors on the motor’s side and back.

Consider how open-loop stepper systems are simple beasts. One simply sets the drive for the motor’s rated current and the drive will do its best to supply that current to the motor at all times, whether the resulting torque is needed or not. This often causes the generation of heat instead of energy towards the application function — and is the reason why open-loop stepper systems typically run hotter than closed-loop counterparts .


Above is a Relative Comparison Chart for StepSERVO closed-loop systems versus open-loop systems. Note the superior performance of the closed-loop stepper motor system as demonstrated in the results of laboratory testing that compare two systems for acceleration (torque), efficiency (power consumption), position error (accuracy), heat generation, and noise levels.

Why to Buy Stepper Drives and Controls at OYOSTEPPER

A stepper motor is an electrically powered motor. Current is passed to the drive shaft, which then rotates in small step-like motions. Stepper motors do not rotate smoothly or continuously. They are designed to power digital devices, which require precise and tightly-controlled motor movements with no feedback. Items containing stepper motors include cars, computers, toys, robotic arms, printers, and robotic model kits.

When purchasing stepper motor drivers, also called controllers, several factors must be taken into consideration. Buyers should make sure that the motor is compatible with the driver, as there are several different types. The number of wires in the motor determines whether a bipolar or unipolar driver is required. Maximum current input and output of the motor also impact which driver to purchase, as do features such as step modes, step frequency, and protection circuitry.

Buying Stepper Drives and Controls on OYOSTEPEPR

OYOSTEPEPR has a large selection stepper drives and controls, available in both new and used condition, and the price range varies significantly across the range. Buyers should use specific search terms to get the most appropriate results results, such as "micro stepper drive," "chopper drive," or "unipolar chopper drive." Buyers can search from the Business and Industrial, Consumer Electronics, and Computer, Tablets, and Networking portals, which also provide relevant search results.

Buyers can narrow their search results by choosing to view specific listing types, such as Buy It Now or auction format. Other result narrowing options include viewing only new or only used items, items within a specific price range, or only items from Top Rated Sellers.

Buyers should ensure the drive is in good working order, particularly if it is a secondhand unit.

Buyers should also ensure that the postage costs are acceptable, and should take note of the estimated delivery time. They should also determine whether the seller offers postal insurance for expensive items. Buyers are encouraged to contact sellers and ask any questions not covered in the item description.

Buyers should choose to buy from sellers who have large amounts of positive feedback, or sellers who possess a "Top Rated Seller" seal. A "Top Rated Seller" seal indicates that the seller has a sterling eBay reputation, and has provided many customers with quality products and great service.

Conclusion
To choose the correct analog stepper drivers or closed loop stepper driver
 buyers must consider their budget, the intended application of the stepper motor, and the required features. Buyers should ascertain which drives are compatible with the motor in question, since some motors will not work with an incorrect drive. The required features are also important considerations. For example, bi-level drives, while very stable and efficient, are not capable of performing micro stepping. This means that despite their reliability, these drives do not offer the same precision and resolution as a chopper drive. For those on a tight budget, secondhand drives in good working order are a good choice. This enables buyers to purchase a high end drive model at an affordable price.