Archive for May, 2012

DC Motor Selection for Dynamic Motion Control Applications

By Dr. Urs Kafader, Technical training maxon motor ag, Switzerland

Finding the right motor is one of the core elements in the selection of dynamic drive components. Due to their high starting torque maxon DC motors with or without brushes are the perfect matches for highly dynamic servo applications. Once the requirements of the application are specified and a general motion control strategy is established, there are a few rules to be respected to get the optimum motor.

Torque and motor size

Often motors are selected from the calculated mechanical power, i.e. from the speed and torque requirement. This can lead to totally wrong results. As an example, take an application running at 25W mechanical power.  The maxon EC 22 with a rated power of 40 W would perfectly fit. The power rating of the motor is based on a high speed of approx. 22’000rpm and a nominal torques of about 18mNm. However, the motor overheats if the required load torque is 40mNm (together with a load speed of 6000rpm this results in 25W!) which is more than twice the nominal torque of the motor.

This leads us to rule no. 1: Select a motor type big enough to fulfill the torque requirements. If necessary use a gearhead to reduce the torque to an acceptable level for the motor. Essentially, there are two torque values to check. The first one is based on thermal considerations. Make sure that the average load torque of the application lies below the rated or nominal torque of the motor. In applications where a working cycle is constantly repeated, the RMS average of the load torque including dwell must be contained within the continuous operating range.

  

Figure 1: The continuous and short term operating ranges of a maxon EC 22 motor. Essentially, the power rating of 40 W is somewhat arbitrary (black hyperbola of constant power). In blue the load operation points for a speed profile with high acceleration torque are added as well. Observe the current scale in parallel to the torque axis reflecting the fact that DC motor current and produced torque are strictly proportional.

The second torque restriction concerns the peak load. For short period of times, the motor can be overloaded without the risk of overheating. Although the details of this overload characteristic depend on the motor design we may state general rule no.2 as follows: Overloading a DC motor by a factor of 2 to 3 for several seconds is possible; the larger the motor, the longer the overload may be.

Covering all operation points

At given voltage applied to a DC motor, the speed decreases linearly with increasing motor torque. The motor speed is highest at no-load. The produced torque is largest at start-up allowing for very high acceleration rates and resulting in the dynamic behavior. Changing the applied voltage produces a parallel shifts this speed-torque line (see figure 2). Hence, any required point of motor operation can be achieved simply by varying the applied motor voltage. In servo applications, that’s what the motion controller that takes care of.

Figure 2: The speed-torque line of a DC motor at the maximum motor voltage (red) and the area of achievable operation points (yellow). The brown line represents the speed torque line at a reduced voltage needed to run the motor at constant speed and torque. Also indicated is the reserve between the maximum speed torque line ant the extreme operation point at the end of acceleration.

Rule no. 3: Make sure that you can cover all the operation points in your application with the maximum available voltage at the motor. Typically, the most critical point is at the end of an acceleration process where the speed and the required torque are highest. The maximum motor voltage may be limited by the power supply used, the maximum supply voltage of the controller and the voltage drop in the controller.

Thick wire –thin wire

For a given motor type or size the mechanical characteristics are quite uniform while the electrical properties can vary a lot depending on the winding used. With a low resistance winding a wide range of operation points can be covered with the motor voltage available; but only at the cost of a lot of current needed to produce the torque. A high resistance winding on the other hand requires a higher voltage but lower currents. Since “current is expensive, voltage is for free” rule no. 4 states the following: Opt for the winding with the lowest current consumption but still fulfilling the third rule with some head room for the controller (“reserve” in Figure 2). “Current is expensive” means that a higher current consumption needs a larger power supply, bigger controller and more elaborate shielding of cables which all adds to the costs. In this context also make sure that the available current from power supply and controller is high enough to cover the maximum required torque.

With/without brushes

In motion controlled dynamic servo applications mostly brushless motors will be selected exhibiting a very high service life and reliability as well as allowing higher speeds.

Brushed motors run without electronic commutation, the control electronics can be made simpler and cost effective.  If the service life requirements are not extremely high brushed motors can still have advantages regarding small size. Graphite brushes are found in larger motors and are better adapted to frequent stat-stop applications. Precious metal brushes are used in small size motors below 10W and are best used for continuous operation at moderate load.

These are a few basic considerations just regarding DC motor selection. There is much more to be observed when it comes to the selection of a complete drive system. Controller and feedback strategies, mechanical layout as well as ambient conditions and boundary restrictions may have an impact on motor sizing.

The forthcoming seminars on “DC Servo Motor Sizing Made Easy” A Practical 1/2 Day Course presented by Dr. Urs Kafader, maxon motor ag provides the practical information you’ll need to successfully select the right DC motor — be it brushed or brushless — for your application. You’ll learn about the interpretation of motor data and how you can use this information for motor sizing. Whether you need high speed and dynamics or just high torque, this seminar will teach you to size a motor + drive with just the right power reserves, avoiding costly oversized motors. 

Click on the following link for more information on the seminars-
http://www.electromate.com/news/?c=calendar

EDITORIAL CONTACT:
Warren Osak       
sales@electromate.com
Toll Free Phone:   877-737-8698  
Toll Free Fax:       877-737-8699
www.electromate.com

 

Patent-pending vertical arresting system from Macron Dynamics opens new possibilities for use of belt driven actuators in vertical automation applications

CROYDON, PA — Macron Dynamics Inc., a manufacturer of linear actuators and multi-axis automation systems, has introduced a patent-pending arresting system designed to promote safer use of belt driven actuators in vertical automation applications.

Macron Dynamics Vertical Arresting System

Macron Dynamics Vertical Arresting System

Macron’s cam lock arresting wedge system™, or CLAWS™, is a U.S. patent-pending arresting system that prevents cart freefall in the event of belt breakage. The system is now an available option on all vertical applications using Macron belt driven actuators and can be retrofitted to most existing vertically-oriented actuators.  The system is not designed for use in horizontal applications.

“There is a perception that belt drives cannot be used in vertical motion applications,” said Chris Robinson, director of engineering at Macron. “We’re finding this misconception is even being taught to engineering students at the university level. This notion is false.”

Macron has been using belt driven actuators in vertical applications for more than 20 years. During that time, in the rare instance of belt breakage, the cause almost always is directly related to misuse of the system, overloading of the cart, or improper maintenance of the system or belt.

“One of the reasons CLAWS™ was developed, was to alleviate any safety concerns regarding the use of belt driven actuators in vertical automation applications,” said Tony Cirone, president at Macron. “With that concern addressed, we believe belt drives offer many advantages over alternative technologies such as screw, chain, hydraulic, and pneumatic motion products and should be considered more widely for vertical applications.”

According to Macron, the primary advantages of belt driven linear actuators are speed and long travel lengths (or height). Both of these attributes introduce added levels of performance, and options for design and system configurations in vertical applications that were limited before Macron’s arresting system.

The patent-pending Macron’s CLAWS™ system uses a tough carbon fiber impregnated Poly Chain® toothed belt. The belt is housed in the actuator’s aluminum beam t-slot, and coupled with a wedge device which integrates with the tension mechanism under the cart. In the event of a belt failure, the wedge device immediately engages the Poly Chain®, preventing the cart and load from falling. Belt failure simulations have been successfully tested with loads of 200 lbs. on a Macron MSA-14S platform.

Macron Dynamics is now offering demonstrations of CLAWS™ upon request.  To learn more or see Macron’s products in motion, visit Macron’s website, www.macrondynamics.com , or call Macron Dynamics, Inc. at 1-800-MACRON-1 (1-800-622-7661).

EDITORIAL CONTACT:
Warren Osak       
sales@electromate.com
Toll Free Phone:   877-737-8698  
Toll Free Fax:       877-737-8699
www.electromate.com

How To: Distinguish the Difference in IP Ratings

Many times a customer will call us looking for a standard or custom motor that needs to be protected from the surrounding environment involving water, dust, or foreign debris.  When this situation presents itself, our Application Engineers start to ask questions about Ingress Protection (IP) rating.  As defined in International Standard IEC 60529, the IP Code classifies and rates the degrees of protection against entrance of foreign objects and liquids.  The IEC standard aims to help users better understand the ratings.

IP ratings can be broken down into two sections – solids and liquids.  This means that the motor is protected against objects down to 1 mm in size and splashing water will not harm the motor.

In some cases, customers ask for special sealing techniques to be applied to the motors. These requests are a result of the application specification for a harsh environment or the presence of liquids in the application. Electromate’s servo, stepper & PMDC motors can be configured up to IP67 or IP68 when needed.

Below is a summary chart of the International Standard IP Ratings-

IP XX

EDITORIAL CONTACT:
Warren Osak       
sales@electromate.com
Toll Free Phone:   877-737-8698  
Toll Free Fax:       877-737-8699
www.electromate.com

DC Servo Motor Sizing Made Easy: A Practical 1/2 Day Course presented by Dr. Urs Kafader, maxon motor ag

This half-day seminar provides the practical information you need to successfully select the right DC motor — be it brushed or brushless — for your application. You’ll learn about the interpretation of motor data and how you can use this information for motor sizing. Whether you need high speed and dynamics or just high torque, this seminar will teach you to size a motor + drive with just the right power reserves, avoiding costly oversized motors.

Maxon "The selection of high-precision microdrives" Textbook

Maxon “The selection of high-precision microdrives” Textbook

Presenter: Dr. Urs Kafader, maxon motor ag, Author of “The selection of high-precision microdrives” Textbook

What You’ll Receive:

  • Textbook: “The selection of high-precision microdrives” (a $65 US value) — A complete, easy-to-read reference guide for motor and drive selection OR you’ll receive an $89 Can. voucher to be used towards your next Maxon order
  • MSP Motor Sizing Software and first step exercises
  • E-Learning software tutorial on USB Stick
  • maxon catalog

What You’ll Learn:

  • Basics of DC motor data. Learn how to interpret motor data sheets and use the speed-torque information for optimum motor sizing
  • Systematic motor and drive selection in the context of your application specific requirements and boundary conditions. This includes optimum power management, control loops, accuracy and ambient conditions
  • Basics of gearhead data and their impact on motor selection
  • Selection criteria for DC motors. Topics include the characteristics of different commutation types for brushed and brushless DC motors and when to use them
  • maxon selection program. Find out how this software-tool can help you during motor selection
  • Application examples. Learn how to extract the key parameters for drive selection from your application: The examples include continuous operation as well as dynamic operation cycles
  • Motion Control: The main features and application possibilities of maxon EPOS controllers

Location/Date:

Hilton Garden Inn Dorval Aeroport
St. Laurent, PQ
Tuesday June 12, 2012
Phone: (866) 788-2518

Directions to the Hilton Garden Inn Dorval Aeroport can be viewed at the following link: Hilton Garden Inn Dorval Aeroport Directions

Radisson Plaza Mississauga- Toronto Airport
Wednesday June 13, 2012
Phone: (905) 364-9999

Directions to the Radisson Plaza Mississauga- Toronto Airport Hotel can be viewed at the following link: Radisson Plaza Mississauga- Toronto Airport Directions

Time:
9:00 am – 2:00 pm. Lunch included

Price:
$89 CDN/person + HST* (*Ontario Only; Quebec registrants will be charged 5% GST only) if pre-registered by midnight May 29th; after May 30th the cost is $109 CDN/person + applicable taxes.

To Register: The Seminar requires pre-registration & payment by Credit Card or PayPal. Click on the link below to be directed to our Online Payment Registration Form.

Maxon Seminar Registration Online Link

Click Here If You Are An Academic

OR call Electromate at 877-737-8698 with your credit card information

AMC Release Family of Single Phase AC Digital Servo Drives

Advanced Motion Control Single Phase AC Servo Drive

Advanced Motion Control Single Phase AC Servo Drive

Advanced Motion Controls of Camarillo, CA is pleased to announce the release of 12 new Single Phase AC Digitial Servo Drives to its broad range of high-performance low-cost Servo Amplifier Product Family.

Single phase power requirements are common in the following industries:

  • Medical
  • Rapid prototyping
  • Packaging
  • Entertainment
  • Lab Automation

AMC’s new DP Single Phase AC Input Amplifiers feature:

  • Smaller footprint vs. 3 Phase models
  • Reduced cost
  • Built-in shunt regulator
  • RMS current limiting compatible
  • 100BASE-T compatible
  • CANopen, EtherCAT and SynqNet models
  • DC supply input with no derating


For more information on the AMC Single Phase AC Input Servo Drive Product Family, click on the link below:

AMC’s Single Phase AC Input Servo Drive Product Family 

EDITORIAL CONTACT:
Warren Osak       
sales@electromate.com
Toll Free Phone:   877-737-8698  
Toll Free Fax:       877-737-8699
www.electromate.com

 

Nippon Pulse Offers 3D CAD Models for Over 1,000 Unique Products

Nippon Pulse CAD Library

Nippon Pulse CAD Library

Nippon Pulse offers a 3D CAD catalog on over 1,000 of its product part numbers, available for download through virtually every 3D CAD software on the market (over 85 formats).   We offer 3D CAD models for our Linear Shaft Motor, tin-can steppers, linear steppers, SCR Nanopositioning linear servo stages, and SLP Acculine linear servo stages.

With the assistance of its flexible search feature, the 3D modeler allows you to choose a product based on only relevant information you know. You don’t need a specific Nippon Pulse part number to find the product your project requires. The 3D modeler will generate the part number based on only the specs you know. This also allows you to easily modify any of our base products with one of thousands of modifications.

For more information on the Nippon Pulse Product Family, click on the link below:

Nippon Pulse Product Family  

EDITORIAL CONTACT:
Warren Osak       
sales@electromate.com
Toll Free Phone:   877-737-8698  
Toll Free Fax:       877-737-8699
www.electromate.com

New EC 60 Flat 100Watt Brushless Servo Motor With MILE Encoder and Protection Class IP 54

The multitude of possible combinations makes the new Maxon EC 60 flat 100Watt the ideal servo motor in a wide range of applications.  Whether the focus is on high nominal torque, on high-dynamic positioning tasks with superb repetition accuracy, or on robustness and insensitivity against environmental conditions, the choice is all up to the end user.

Maxon EC60 Flat 100Watt DC Brushless Servo Motor

Maxon EC60 Flat 100Watt DC Brushless Servo Motor

Versatility:
Various windings for battery-powered and industrial applications, flat design for small spaces.

Power:
Nominal torque up to 319 mNm, iron-core with almost inexistent detent.

Robustness:
Radial load 100 N, protection class IP 54 (spray water), preloaded ball bearings, grounding connection, environmental conditions of -40 to +100°C.  The EC 60 also features an optional MILE encoder which optimizing the use of the EC 60 flat motor in high-precision applications and positioning tasks. 

Behind the abbreviation MILE hides Maxon’s Inductive Little Encoder, the worldwide smallest inductive rotary encoder.  Its operating principle is based on the detection of high-frequency inductivity which generates eddy current in an electrically conducting target.

The advantages of a high-frequency inductive method of measurement compared to traditional encoders are:

  • High robustness towards dust or oil vapor, thus making additional protective measures, such as a cover, unnecessary.
  • High speed.
  • Insensitivity against interference pulses (for example from PWM controllers or motor magnets).

The EC 60 flat’s extraordinary characteristics come into full effect in battery-powered mobile applications, as well as in the industrial field; for example in variable flow valve drives, in dialysis systems, or in direct drive centrifuges with extended service life and large radial loads.

For more information on the Maxon EC 60 Flat DC Brushless Servo Motor, click on the link below:

Maxon’s EC60 Flat 100Watt Servo Motor  

EDITORIAL CONTACT:
Warren Osak       
sales@electromate.com
Toll Free Phone:   877-737-8698  
Toll Free Fax:       877-737-8699
www.electromate.com


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