Linear motors fill an important role in providing a robust and high precision direct drive solution in many high performance applications. In order to achieve the highest level of performance, the linear motor system must be commissioned properly. This blog post addresses key areas to consider when setting up and commissioning a linear motor system. It is always important to refer to the installation and setup instructions provided by the manufacturer.
System wiring and cable management - Typically, a linear motor system consists of a stationary magnet "track" and a moving coil or "slider". This means you will have cables that are moving with the slider - so cable management is important. Major items to consider include cable flexibility, bend radius, and grounding and shielding practices. Wiring typically will consist of power leads, feedback, Hall-effect, and thermistors.
Initial Power-up - Once the motor is installed and wiring confirmed, begin the set-up process by making sure the drive's peak currents are reduced to safe levels, and place wooden blocks at each end of travel stop. A mis-wired linear motor could run away at high output forces, causing injury or even damage to the equipment.
Continuing on with the configuration, most servo drives have some method of setting up specific drive parameters associated with the specific motor you are driving. These parameters help set up how the motor will be commutated and configure the initial tuning loops. With the Kollmorgen AKD drive, most of the parameters are auto populated by selecting the correct motor model from a drop down list. In addition to the basic motor parameters, temperature sensing and feedback resolution also must be entered. It is very important to have the feedback resolution set correctly. In the AKD drive, resolution is defined by the magnet pitch divided by the encoder resolution.
Initial Testing - Encoder direction, motor phase sequence, and Hall sequence must match exactly for the system to both commutate properly, and the motor move as expected. The AKD drive has a means to test feedback resolution, as well as proper commutating direction within the Workbench environment.
Final Set-up - With the encoder and Halls properly aligned with motor phasing, and with the peak currents limited, a wake and shake process can be run to complete the commutation setup. Now you can carefully exercise the motor back and forth using short moves to be certain all is working as expected - and now your set-up is complete! You can continue to fine tune the system and optimize the performance on your machine.
Successful commissioning of a linear motor will ensure you are getting the most out of your system. You will be able to achieve the performance and precision you expect from a linear motor solution.