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Motion System Design
Better by Design: Servodrives

Better by Design: Servodrives

Over the last decade or so, thanks to shrinking electronics, servodrives have become increasingly compact. This has spurred more engineers to distribute controls, and install drives (for both single and multi-axis designs) closer to the motors they operate. That said, sometimes size, cost, and networking complexity are still issues. In distributed designs, maintaining the efficiency of traditional installations can also pose challenges.

To address these issues, AMK Drives & Controls Inc., Richmond, Va., has now expanded its compact AMKASMART distributed line to include 98% efficient iC servodrives. These feature a servo controller as well as power supply — combining the technologies in one envelope — for units that can control linear and rotary motors, both synchronous (permanent magnet) and asynchronous.

Convection cooling, integrated fan, and cold-plate versions allow customized setups. In the latter, the cold plate comprises the unit's bottom; when mounted on a machine frame or any effective conductor, it successfully removes heat to protect the drive's mission-critical IGBTs.

The iC drive also takes power connectivity further — allowing ac or dc supplies to be looped through to minimize cabling. In short, the units include daisy-chainable output for both Vac and 540 Vdc — useful where several axes are operated. Here, an engineer operates the first iC drive off of 400 to 480 Vac, and then daisy chains one or more iCs off of it. In fact, even AMK iX drives — accepting only high-voltage dc bus input at 540 to 650 V, and typically run through an external power supply for multi-axis designs — can also be run through an iC drive.

Five multifunctional digital I/Os allow direct connection of sensors, actuators, and switches to the machine; an analog I/O allows myriad connections to variable parts, dancers, and so on that feed directly into drive. Fast and secure realtime Ethernet communication via EtherCAT or Sercos III (with a minimum cycle time 500 µsec) allows networking plus communications with higher-ranking controls.


On display: AMK iC Series drives

Key features: Suitable for single-axis machines and modular configurations, the iC drives are 98% efficient and eliminate the need for a switch cabinet. Individual electronic functional units can be configured to allow closed-loop control of servomotors (to 10 kW peak) practically anywhere.

What else: Subcomponents normally part of the drive cabinet are integrated — including a 24 Vdc power supply to power the electronics, plus a brake chopper — so that the design can quickly decelerate loads. Standard Safe Torque Off (STO) functionality means that during STO motor/drive torque cutoff, IGBT firing circuitry is interrupted internally through a daisy-chained brake control circuit for safety to Performance-Level d.

What it means to you: Decentralized control with IP65 protection; reduced drive cabinet and wiring requirements for cost savings. Drive allows daisy chaining with simple shielded cable (and none of the special connectors or cables required by other units.) Torque, velocity, and position control in 62.5 µsec, 125 µsec, and 250 µsec, respectively; software commutation, cyclical and position setpoint filter; load modeling, homing cycle, parameter storage, diagnostics, and protective functions.

Innovator: AMK Drives & Controls Inc.
(804) 222-0323 •

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