Key features and shortcomings of Stepping Motor

Stepper motors have numerous advantages:

They ensure univocal conversion of control impulses to displacement and can be employed in open-loop control applications;
Have a wide range of control frequencies;
They provide precision and high resolution for positioning;
Allow for sudden starting, stopping or reversing without losing steps;
Can hold their position;
Are highly compatible with numerical control.
But they also have disadvantages like:

Fixed step value (angular displacement) for a given motor;
Relatively low speed;
Low torque;
Low power efficiency.
The characteristics of a stepper motor such as linear stepping motor or closed loop stepping motor are strongly dependent to load and type of the actuation mechanism it is employed in, so that:

A certain resolution for the complete actuation system is imposed;
Loads, forces or inertia must be reduced at the motor’s shaft;
A certain speed characteristic must be defined for accomplishing movement;
The ratio between loads reflected to the motor’s shaft and the actual torque of the motor must be kept in adequate limits.

Are all closed-loop stepper systems created equal?

How do I get the right control for my application?
Manufacturers apply the term "closed-loop stepper" to a wide array of controls. Here, we'll spell out how the three most common closed-loop stepper control schemes work and highlight their advantages and disadvantages.

Are all closed-loop stepper systems created equal?
No. Some manufacturers give the closed-loop stepper systems similar-sounding descriptions, which confuses the marketplace. As proof of the confusion, it's not uncommon that a designer requests one capability and actually needs another.

What are the most common closed-loop stepper systems?
There are three common types: Closed-loop stepper with step-loss compensation; closed-loop stepper with load position control; and closed-loop stepper servo control. Stepper-drive manufacturers call them all "closed loop" but the three have distinct functionalities.

What are the functionalities of these closed-loop stepper systems?
Closed-loop stepper with step-loss compensation is the most common type of closed-loop stepper control. The analog stepper driver operates as a micro-stepping drive and typically receives pulse and direction commands to move to the desired position. An encoder tracks shaft or load position. If lost steps are detected, a compensation algorithm inserts additional steps so that the motor shaft (or load) arrives at the desired position.

How do I get the right control for my application?
Machine builders must ask: Which control scheme does the application require? It may not be immediately apparent which control scheme the drive uses. Therefore, ask the manufacturer for details and review the documentation to ensure you get the right control scheme.

OYO High Torque Nema 34 Hybrid Stepper Motors TBNS001OP

Something about NEMA 23 Holding Brakes

OYOSTEPPER Products is pleased to announce the release of holding brakes for select step motors in the NEMA 23 frame size. These step motors provide additional functionality for applications which require holding torque to be maintained when power is removed from the motor.

Holding brakes offered by OYOSTEPPER are spring-set type brakes that must be powered by 24 volts DC to release the brake mechanism. This is commonly referred to as “power off” and is the preferred style for motion control applications. Controlling the brake is handled by a discrete output on the stepper drive or another controller like a PLC or motion controller. Many OYOSTEPPER drives offer outputs specifically designed to control the holding brake, such that the brake will be automatically engaged whenever the motor is unpowered (and automatically disengaged when the motor is powered or moving).

This initial offering of holding brakes for step motors is available as an option on the following most popular NEMA 23 frame step motors. Click to view specifications and pricing:

HT23-594B
HT23-598B
HT23-601B
HT23-603B
A common application for holding stepping motor brake is one in which a belt drive linear actuator is mounted vertically. When power is removed from the motor the belt and load can drop, potentially causing harm to the machine and/or human operators. Holding brakes can help to alleviate this unsafe condition by automatically holding the motor and load in position even when all power has been removed from the motor.

Basics of Stepper Motors You Should Know

Operation & Structure
A stepper motor rotates with a fixed step angle, just like the second hand of a clock. Highly accurate positioning can be performed with open-loop control thanks to the mechanical structure within the motor.

Accurate Positioning (Number of Steps)
While having full control of rotation and speed, the simple structure of stepper motors is achieved without using electrical components, such as an encoder within the motor. For this reason, stepper motors are very robust and have high reliability with very few failures. As for stopping accuracy, ±0.05° (without cumulative pitch errors) is very accurate. Because positioning of stepper motors is performed by open-loop control and operated by the magnetized stator and magnetic rotor with small teeth, stepper motors have a higher follow-up mechanism toward commands than that of servo motors. Also, no hunting occurs when stopping stepper motors. They are also excellent in belt drives, which have low rigidity.


Useful for Speed Control and Position Control
When pulses are input to a driver through a pulse generator, stepper motors position according to the number of input pulses. The basic step angle of 5-phase stepper motors is 0.72° and 1.8° stepper motor for 2-phase motors. The rotating speed of the stepper motor is determined by the speed of the pulse frequency (Hz) given to the driver, and it is possible to freely change the motor rotation by simply changing the number of input pulses or frequencies to the driver. Stepper motors not only serve as position control motors, but also as speed control motors with high synchronization.


Stepper Motors Uses:
• High frequency, repetitive positioning of fixed step angles
• Positioning that requires long stopping time due to width adjustment, etc.
• Fluctuating loads and changing rigidity
• Positioning that divides 1 cycle
• Motor shafts that requires synchronous operation

See more:https://www.oyostepper.com/

The Motor Encoder: When Closed Loop Control is Essential

An stepper motor encoder for sale is a rotary device that can be mounted onto an electric motor. It provides closed loop feedback signals, tracking the motor shaft’s position, speed, or both.

At first, this functionality might seem redundant. Isn’t precision control essentially what the stepper does on its own? The answer, it seems, is yes and no. Recent research has shown that the apparently “unnecessary” guidance provided by the encoder can have a powerful impact on how well a stepper motor works.

Motion controller brand Galil conducted a series of side by side tests between open and closed loop stepper motor systems. Their team discovered that the addition of an encoder could produce appreciable gains in major performance metrics.

Compared to the open loop system, the closed loop stepper motor offered:

Significantly improved velocity smoothness;

Reduced overall current consumption;

Higher torque at lower velocities than comparable three-phase brushless servo motors.

Galil's researchers determined that “dramatic” performance gains for stepper motors were possible by integrating a positional feedback device along with a two-phase brushless amplifier. Their testing methodology and results have been made public on their website.

These results are truly exciting news in the motion control world. Engineers at all levels can enhance stepper motors into even more powerful and economical solutions through the use of readily available encoder technologies.

KNOWLEDGE of CLOSED LOOP STEPPER SERVOS FOR EVERYONE

Why stepper motors? What about other types of motors?

Choosing an appropriate stepper motor such as nema size 17 can be difficult and time consuming. This webpage is intended to help you easily and quickly select a good stepper motor for your project. There is a lot to cover, so consider this the first part in the series.

Why stepper motors? What about other types of motors?
Stepper motors online are by far the most common types of motors used for CNC Machines. Stepper motors have a unique property that makes them particularly well suited for CNC motion. Each time a stepper motor receives a pulse, it only moves a certain amount. For a full step, this is usually 1.8 degrees and for a half-step this is usually 0.9 degrees. The reason this is important is because the computer running the motor doesn’t need to sense the actual position of the motor because the motor’s position can be calculated solely by how many pulses have been sent out.


Another possibility is to use PWM motors. These motors produce different torque depending on the duty cycle of a square wave signal it receives. However, a more complicated controller and an expensive quadrature encoder must be used to determine the current location of the motor at all times. This is a closed loop control system, where the system reacts based on position data which is detected through a sensor.

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