Stepper motion systems addendum

Cost, simplicity, and continuing innovation are keeping stepper motion technology competitive—as described in the May 2013 main article. Additional developments and perspectives on motor-drive integration, controls, component miniaturization, and stepper motion system suppliers are provided here.

04/22/2013


Stepper motion systems compete intensely with servo systems for many applications, but that competition takes place over a relatively narrow range of power and speed. As mentioned in the main article, torque output of step motor falls off substantially above 900 rpm running speed. There are exceptions to that rule-of-thumb, of course, and some step motor designs can handle much higher operating speeds. However, servo motors dominate at higher speed and torque requirements.

While step motors are not rated for power, an “equivalent power” calculation puts virtually all of them under 0.75 kW (1 hp) output—and many models have much lower capacity. Larger size step motors have a practical rather than technological limitation. One notable example of very large steppers is a 168-mm (6.6 in.) diameter, 2-phase, 240 Vdc model built by former German company Zebotronics. Its output power calculates to a remarkable 1.22 kW at 900 rpm. These motors are still in the marketplace from Stögra Drives in Germany. Servo motors range from small sizes that compete with step motors up to extremely large units with corresponding high torque and speed performance.

www.stoegra.de 

Motor-drive perspective

Combining motors and electronic controls in one unit has been a major engineering development. The “marriage” of these two technologies—normally operating in disparate environments—took substantial time and effort to consummate. Step motors were probably the first to be integrated with an electronic drive because of their predominantly smaller physical size. One of the earliest examples of such a product appears to be “Intellimotor,” a 2-phase step motor and intelligent controller combination, introduced in 1989 by the former U.S. company Intellico Inc.

Various stepper (and servo) product manufacturers in Europe, Japan, and the U.S. went on to develop integrated motor, drive, controller, and feedback packages. Intelligent Motion Systems (IMS) was one notable U.S. developer of this technology with the MDrive product line. IMS was acquired by Schneider Electric in 2008 and renamed as Schneider Electric Motion USA at the end of 2012 (see main article). Such motor-drive packages are seeing increased usage in factory automation where relatively clean working environments and high productivity requirements favor this technology. Networking options are also being added to integrated motor-drive products. EtherNet/IP, CANopen, and Modbus/TCP are available options for various MDrive configurations, but not all options apply to every model of MDrive.

www.motion.schneider-electric.com 

Oriental Motor offers two integrated stepper motor-drive product lines: ASX Series and PKA Series. The latter series combines a controller, microstepping driver, and 5-phase motor (0.72-deg full-step angle) in one unit. Todd Walker, OM’s national marketing manager, told Control Engineering that PKA Series is new to the U.S. and has an expected May 2013 release date here. 

Stepper motion system products come from a large number of manufacturers worldwide. Here is a sampling of supplier companies.

Select list of stepper motion system suppliers

(controller, drive, or motor original equipment manufacturers)   

Company

 

Integrated motor-drive available

 

URL

 

Advanced Micro Controls Inc.

 

 

 

www.amci.com

 

Aeroflex

 

 

 

www.aeroflex.com/ams/motion/motion-motors.cfm

 

Aerotech Inc.

 

 

 

www.aerotech.com

 

Anaheim Automation Inc.

 

Yes

 

www.anaheimautomation.com

 

Applied Motion Products Inc.

 

STMR integrated steppers

 

www.applied-motion.com

 

Beckhoff Automation

 

 

 

www.beckhoff.com/drivetechnology

 

 

B&R Industrial Automation Corp.

 

 

 

www.br-automation.com

 

 

ElectroCraft Inc.

 

 

 

www.electrocraft.com

 

Empire Magnetics Inc.   (a)

 

 

 

www.empiremagnetics.com

 

Galil Motion Control

 

 

 

www.galilmc.com

 

Kollmorgen

 

 

 

www.kollmorgen.com

 

Lin Engineering

 

Silverpak Series

 

www.linengineering.com

 

National Instruments Corp.

 

 

 

www.ni.com

 

Nippon Pulse America Inc.

 

 

 

www.nipponpulse.com

 

NMB Technologies Corp.

 

 

 

www.nmbtc.com

 

Oriental Motor USA Corp.

 

ASX Series

PKA Series (c)

 

www.orientalmotor.com

 

Parker Electromechanical Automation Div.

 

 

 

www.parker.com

 

Phytron Inc.

 

 

 

www.phytron.com

 

Sanyo Denki America Inc.

 

Sanmotion F Series

 

www.sanyo-denki.com

 

Schneider Electric Motion USA

 

MDrivePlus

MDrive Hybrid

 

www.motion.schneider-electric.com

 

Stögra Antriebstechnik GmbH

                   (b)

 

 

 

www.stoegra.de

 

        (a) -  severe environment and special step motors

        (b) -  step motor range up to very large sizes

        (c) -  2013 introduction in the U.S. 

- Information compiled by Control Engineering

 

Control advances, miniaturization

The main article mentioned the significant role control innovations play to advance stepper motion system capabilities. One example—Hybrid Motion Technology (HMT) from Schneider Electric Motion—applies methods derived from servo motion technology to enhance stepper motor systems. “HMT is a proprietary, real-time hardware monitoring system that enables stepper motors to overcome numerous negatives, including stalling,” according to a Schneider Electric Motion spokesperson.

When applied to step motors, HMT is said to prevent:

  • Loss of synchronization due to temporary or continued overloads
  • Excessive acceleration or deceleration
  • Excessive slew speed.

Compact motion terminals from Beckhoff Automation, such as EL7051, can drive stepper motors rated up to 8 Amp and 80 Vdc directly from the I/O system, using the company’s EtherCAT technology. Courtesy: Beckhoff Automation.This recent technology development is available with MDrive in models using NEMA size 17, 23, and 34 step motors.

Miniaturization is another development affecting stepper motion systems. Bob Swalley, motors and drives specialist at Beckhoff Automation, regards miniaturization of devices as the major, overriding trend particularly for drive technology. For example, Beckhoff offers compact I/O terminals for stepper control—covering voltage ranges from 24 V to 80 V (see photo). “These stepper motor I/O terminals can lower costs when compared to typical stepper amplifiers used today,” Swalley said. More recently, machine-mountable I/O boxes for stepper control in protection class IP 67 have also become available. “The basic technology enabling this advance was pioneered by Beckhoff almost 10 years ago,” Swalley added. “This ruggedized technology permits stepper amplifier installation outside an electrical cabinet, further reducing costs and machine footprint size.”

www.beckhoff.com/drivetechnology 

- Frank J. Bartos, PE, is a Control Engineering contributing content specialist. Reach him at braunbart(at)sbcglobal.net.



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