Views:18 Author:Site Editor Publish Time: 2018-01-11 Origin:Site
Stepping systems have been used in industrial automation for many years to accurately position machine tools, x-y tables, feeders, etc. Unlike typical AC variable speed drives (used for velocity control), a stepping drive and Stepper Motor is used primarily for position control. A typical single axis Stepping system consists of a Stepper Motor controller/ indexer, a motor drive, a motor (with or without gearbox), and a power supply. A stepper is typically commanded by two digital inputs: a digital pulse train and a direction bit. A single pulse on the pulse input moves the motor one step increment in the direction (CW or CCW) set by the direction bit.
· Controller/ Indexer
The controller/ indexer is responsible for outputting the pulse and direction commands to the drive. PLCs distributed by MotionKing, as well as many other 3rd party products, can be used to control the SureStep line. The frequency of the pulse train controls the velocity of the motor, where the number of pulses determines the length of the move. The direction signal determines in which direction the motor will rotate.
· Stepper Power Supply
The power supply plays a dual role: it supplies the main power to the motors as well as the power to optically-isolated digital inputs. The motor power is typically provided by a linear non-regulated power supply. The SureStep power supply has a 32 VDC @ 4A (when fully loaded, 41 VDC unloaded) output to supply power to the motor via the drive. Also, the digital interface between the drive and the controller/ indexer should be powered by the isolated +5 VDC (500 mA max) regulated output. The motor power and the digital interface power are typically isolated since the motor power source is extremely "noisy" when loaded. Using the motor power for the interface might lead to false pulse commands thereby creating undesired system movement. One SureStep power supply can provide both motor power and interface power to a least 2 complete SureStep drive/ motor combinations.
· Stepper Drive
The drive translates the pulse and direction commands from the controller/indexer and converts them into actual motor movement. For each pulse from the controller, the drive will move the motor "one step" in the direction indicated by the direction command. The SureStep microstepping drive provides 4 different step resolutions for use in a wide range of applications. They range from 1/2 stepping (400 steps/rev) to 1/50 stepping (10,000 steps/rev) when used with a 1.8隆茫 (200 full steps / rev motor). The SureStep drive can be configured for use with all SureStep brand motors, as well as many other 3rd party 2-phase, bipolar Stepper Motors that require 0.4 to 3.5 Amps/phase to drive them. The drive also features a "test mode" that allow the drive and motor system to be tested without being connected to a controller/indexer. This feature enables an on-board indexer that moves the motor 1/2 revolution back and forth in half-step mode so the user can easily "move" the system while troubleshooting. An idle current cutback feature can be used to conserve power and reduce heat by cutting the power to the motor by 50% if no step pulses are received for 1 second. All the SureStep drive settings are done through a 9-position dip switch, which means that NO SOFTWARE or external resistors are required to configure the drive.
· Stepper Motor
The motor converts the power from the drive into rotational movement. Unlike AC motors, Stepper Motors have 100% current (idle-current cutback disabled) applied to them all the time regardless of load on the motor. The motor is moved in "steps" (one per command pulse) and will hold at its present position if no command pulses are received. The SureStep line of motors are built to provide high-torque for their frame size which ranges from NEMA 17 to 34. All SureStep motors have only 4 leads and are connectorized, which greatly reduces the chance of mistakes while wiring the motor to the drive. Many other motor brands typically have 6 or 8 leads, which can cause confusion while wiring the system.