Selecting the Appropriate Stepper Motor Driver Pack

What is an Anaheim Automation Driver Pack?

Anaheim Automation developed the Driver Pack to simplify the design of automated systems. Driver Packs are combination packages containing stepper motor drivers, optional indexers, interface circuitry and matched power supplies. Anaheim Automation Driver Packs most often contain bilevel drivers, but Anaheim Automation also manufactures a 2.5Amp, 5Amp and 10Amp Microstep Driver Packs to broaden the selection. In addition to their use in OEM equipment, Driver Packs are used to upgrade older equipment, develop prototype machines, increase system performance, or serve as on-the-spot substitution controls for testing. Installation is simple: just connect the stepper motor leads to the Driver Pack, hook up the system controller, i.e. computer or PLC, plug in the standard line cord, and start operation.

NOTE: Other input voltages are available upon request.

Precision Incrementing: Applications include robotics, process control, automated machines, special filming or projection effects, packaging, labeling, medical diagnostics, to name a few.

Advantages: The matched components simplify equipment design while the compact package makes installation easy, and takes the guesswork out of component selection.

Performance: Anaheim Automation Driver Packs ensure outstanding stepper motor performance.

Equipment Upgrades: Up-to-date circuitry can substantially improve performance in older equipment. These compact Driver Packs make test and evaluation easy. They are simple to install and make improvements permanent.

Test and Service: Drive Packs are portable and make on-the-spot substitution and testing quick and easy.

Compatibility: Whether your machine or process uses a PLC, computer, or a standalone motion controller, Anaheim Automation has a Driver Pack to match your application.

Packaging Options: Enclosed Packages or OEM Open-frame Styles. Lower-cost version, meant to be mounted inside an enclosure.

Budget Minded: Cost-Effective Development Tool. Easy-hook-up and matched components make installation quick and easy; less labor-intensive.

Diverse Customers and Applications: Excellent OEM and End-User Production Hardware, serving many industries where position control is required.

Custom Designs Available: Further savings in that exact application requirements are met. Customers don’t pay for features they don’t need!

The Driver Pack was a major innovation by Anaheim Automation that incorporates stepper motor drivers and controls with an integrated power supply in one compact package. Anaheim Automation offers many off-the-shelf Driver Pack models in the following series: DPC, DPD, DPE, DPF, DPG, DPK, DPM, DPN, DPS, and DPY. These models come in two styles: models are fully enclosed, except for the DPS series, which is an open-frame unit. The largest units contain a high capacity power supply (800 Watt), for use with high power stepper motors. Anaheim Automation can equip a Driver Pack to include up to four drivers (model dependent); all models offer compactness without sacrificing performance.

Two different types of drivers are available in Driver Packs: a bilevel driver with either clock and direction control, or clockwise and counterclockwise clock, a microstep driver with clock and direction control.

•    1 - 4 Axes per Package Provides Flexibility and Saves Space
•    Matched Power Supplies for each Driver/Motor Combination
•    0.5 - 12.5 Amps, Bilevel and Microstep Drivers (model dependent)
•    Optional Indexers and Programmable Controllers can be Integrated in the Driver Pack
•    Fan Cooled for Added

Some Driver Packs combine a bilevel driver with a manual and ramping pulse generator. Also available are Driver Packs with high-performance (high-voltage) bilevel drivers, programmable controller(s), and manual preset indexer(s).

Indexers can be packaged along with the driver(s) to produce a Driver Pack which is easy to control from computers or programmable logic controllers (PLC’s). These Driver Packs provide excellent OEM and end-user production hardware. Many customers have found these packages to be an indispensable and cost-effective developmental tool. The complete solution to a customer’s requirement is the salient feature of the Driver Pack.

NOTE: Custom designs are available to further reduce system complexity and cost!

Drivers

Drivers translate clock and direction signals from indexers or other controls into phase current sequences required to run stepper motors. But sequencing phase currents is only the beginning, since actual stepper motor performance is dependent upon a number of factors, the most important of which is; how fast the drivers can push the current to the required level in the stepper motor winding being turned on at the beginning of each step, and how fast the driver can de-energize the windings being turned off at the beginning of the next step.

Bilevel Drivers used in some Anaheim Automation Driver Packs do not use high frequency switching techniques as chopper drivers do. Anaheim Automation’s bilevel drivers begin each step with a high voltage to quickly bring the current up to operating level, and then shifts to a low voltage to sustain performance far better than many stepper motor specifications. Stepper motor direction control options are C&D, providing a single clock input with a direction control line, and CW/CCW providing two clock inputs, clockwise and counterclockwise (jumper selectable).

Driver Packs operate four-phase, 4, 6 and 8 lead motors, with stepper motor current ranges from .5 to 12.5 Amperes per phase, produce outstanding torque/speed characteristics and provide users with mode select a choice of full-step dual (1.8 degrees per step) or half-step (0.9 degrees per step). NOTE: These features are model dependent, and not all Driver Pack series will have all features.

Full-step operation is recommended for only those applications that specifically require that mode, such as retrofitting existing full-step systems. Half-step operation is preferable because it is more stable, produces finer resolution, requires less power, produces less heat, and produces a somewhat higher RPM. Microstep Driver Packs will produce even finer motion, by dividing the step angle further.
Driver Packs have a power turn-off feature for stops with memory, making it possible to de-energize a stepper motor without disturbing the position logic. This feature can be used to reduce stepper motor heating and conserve power. This also allows for operation of a number of motors from the same Driver Pack power supply, taking into consideration the overall power supply capacity.

Define Your Stepper Motor Driver Pack with these Simple Steps:

1.    Start with Stepper Motor and Control Device compatible with your application. See Selecting a Stepper Motor System for more details.
2.    Employ one Driver per Stepper Motor; matched with Motor current.
3.    Driver Packs include Power Supply Compatible with the Driver(s) and Stepper Motor(s). However, be careful not to exceed the capacity of the power supply. Take into consideration how many stepper motors are operational at one time.
Use Single or Dual Indexer or Pulse Generator(s) as required.

4.    Assign Interface to adapt
Indexer to Control Device I/0:
      •    RS422
      •    PLC
      •    Manual Switches (See Accessories)
5.    Configure the Driver Pack containing items 2 through 5 as applicable.
6.    If unsure, contact Anaheim Automations Applications Engineering Department


General Considerations – See Selecting a Stepper Motor System Guide for more detailed information.

The number of axes running at the same time, load characteristics, performance requirements, and mechanical design including coupling techniques, must be considered before the designer can effectively select the most suitable stepper motor and Driver Pack combination for a specific application. The following factors must be considered to obtain the optimum solution for each axis. It is not uncommon that different axes will require a different stepper motor.

Parameters to be Considered for each axis:

a)    Distance to be traversed
b)    Maximum time allowed for a traverse
c)    Desired detent (static) accuracy
d)    Desired dynamic accuracy (overshoot)
e)    Time allowed for dynamic accuracy to return to static accuracy specifications (settling time)
f)    Required step resolution (combination of step size, gearing and mechanical design)
g)    System friction: The stepper motor must provide torque to overcome any system friction. A small amount of friction is desirable since it can reduce settling time and improve performance.
h)    System inertia: An object’s inertia is a measure of its resistance to changes in velocity. The larger the inertial load, the longer it takes a stepper motor to accelerate or decelerate that load.
i)    Speed/Torque Characteristics: Torque is rotational force (in ounce-inches) defined as a linear force (in inches). The capacity of the stepper motor must exceed the overall requirements of the load. Individual speed/torque curves should be consulted for each application.
j)    Torque-to-Inertia Ratio: Defined as a stepper motor’s rated torque divided by its’ rotor inertia. This ratio (measurement) determines how quickly a stepper motor can accelerate and decelerate its’ own mass.
k)    Torque Margin: Whenever possible, a driver that can provide more torque than is necessary should be specified. This torque margin allows for mechanical wear, lubricant hardening and other unexpected friction. Selecting a driver that provides at least a 50% margin above the minimum required torque is ideal.

1.    Calculation:

Measurement of inertia, friction and wok loads reflected to stepper motor. Load inertia should be restricted to no more than four times stepper motor rotor inertia for high performance (relatively fast) systems. A low performance system can deliver step accuracy with very high inertial loads, sometimes up to ten times rotor inertia. System friction may enhance performance with high inertia loads.

2.    Experimentation:

Tailoring or Experimentation for motor/driver sizing is almost always necessary because of dynamic changes in system friction and inertia (load anomalies) that are difficult to calculate. Stepper motor resonance effects can also change when the stepper motor is coupled to its’ load.

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