Stepper Motor Drives

Simplifying interfaces, making solutions more compact and lowering installed cost are the goals that are all working together to shape new stepper driver designs. The net result is new products that provide advanced control capabilities, and stand alone drives and/or integrated motor-driver packages that provide both maximum torque density and simplified operation. The driving forces for manufacturers are more sophisticated, smaller products that deliver better torque output and improve motion performance. There is an emphasis on refining auto-tuning features, detailed refinements of dynamic motion performance and new networking options. With increases in processing power available, suppliers are maximizing their control software algorithms with more robust, embedded control software solutions.

MINIPAK INTEGRATED STEP MOTOR AND DRIVER

Lin Engineering's MiniPak integrated product is designed for small applications, and combines a Lin size 11 step motor with a drive/control board that uses the Trinamic TMC222 drive chip. The 211-13 provides high torque in a small package and produces 9.2 oz-in of holding torque. The NEMA size 11 motor (1.8 degree) measures 1.1 inch square with a length of 1.24 in. The voltage operating range of the drive is from 8 to 29V dc and is capable of 2 to 16x microstepping. The driver board contains a fixed frequency PWM current control with automatic selection of fast and slow decay mode, as well as a built-in ramp generator for autonomous positioning and speed control. An MCU unit adds RS485, homing, two-module handling, parameter storage, constant velocity mode, two demo modes and an ASCII interface. When the MiniPak is used with the MCU board, the user can daisy chain up to 32 axes.

APPLIED MOTION PRODUCTS STEPPER DRIVE

Engineered to satisfy the price and performance needs of OEMs, the ST5-S from Applied Motion Products is designed to deliver up to 5.0A with 90-135V ac input while optimizing stepper motor performance. The ST5-S can be controlled by step and direction inputs or via serial communications. Self-test and auto setup features measure and configure motor parameters automatically, while anti-resonance technology eliminates midrange instability for higher motor speeds and fuller use of available torque. Demand signal smoothing reduces extraneous system resonances for smoother motor performance and reduced wear on mechanical components. Torque ripple smoothing adjusts the current waveform to reduce low speed torque ripple for smooth motion at low motor speeds. Additionally, MicroStep Emulation provides smooth motion for systems that require low step resolutions. Setup and configuration is accomplished with graphical Configurator software. The drive can be configured from a drop-down menu, or the user can create custom motor configurations if desired.

DRIVEMAX STEP MOTOR AND DRIVER

The DriveMax Series of integrated step motor and driver from Arcus Technology are offered in NEMA 17 and 23 frame sizes. The Basic Driver version is rated at 2.5 Amps, 24V dc and can operate at full-step, half-step, 4X and 8X micro-stepping. The Advanced Driver version is rated at 3.0 Amps, 48V dc and can step from half-step to 500X micro-stepping with any increment in between. Parameters are set through a cable that plugs between the DriveMax and a USB port on a PC. The DriveMax Series of integrated motors are also available in closed-loop driver and controller versions using integrated encoder and patented StepNLoop control. Closed-loop driver versions come with pulse/dir/disable and alarm/in-pos signals. Controller versions are available with RS-485 and MODBUS-RTU communications with limit and home inputs. The ControlMax Series can convert a DriveMax integrated motor into a motion controller using a plug-in modular approach offered in USB 2.0, RS-485 and Ethernet communications.

INTEGRATED MOTOR DRIVER

An integrated motor driver with encoder from RMS Technologies is a NEMA 17, 1.8 degree bipolar step motor that operates from +12 to 24V dc. The IMDE17 comes in three different sizes and provides phase current ranges from 0.35 to 2.0A peak. Step resolutions available include full, half, 1/4 and 1/8 microsteps. The motors feature optically isolated step, direction, and disable/enable inputs, selectable current reduction of 33 percent, low power dissipation, efficient current control plus thermal shutdown and under-voltage protection capabilities. The motors offer up to 85 oz-in (60 N-m) of holding torque. The IMDE17 offers an optical encoder option. The encoder can be used to monitor speed, direction, and distance of travel. A controller measures the process' speed by simply timing how fast the encoder supplies pulses. It determines direction by monitoring which channel (A or B) rises first. It determines distance traveled by counting the number of pulses sent since movement began.

HIGH-SPEED BLDC MOTOR-DRIVER

New brushless dc motors from Oriental Motor USA adopt a new design for its BLF series motor, gearhead and driver. The new series offers high performance speed control, with an increased speed range of 80 to 4,000 rpm (50:1), plus an IP65 rated that provides splash and dust protection. The BLF series driver introduces a detachable digital operator unit that operates as both a data input unit and a digital display that can be used up to 16.4 feet (5m) away from the installed driver. The user can program eight separate speed levels. Each speed can be set in units of 1 rev/min with separate acceleration and deceleration values. Detection of various motor and driver error functions including overload, overvoltage, low-voltage, missing phase, overspeed and overcurrent immediately stops the motor and outputs an alarm signal. The driver utilizes three speed display modes to help the user including motor speed display, conveyor speed and a load factor display.

STEPPER MOTOR DRIVES WITH FIELDBUS ON BOARD

A new version of Berger Lahr's SD3 line of 3-phase stepper motor drives now offers fieldbus technology on board. The compact unit integrates the power supply and a mains filter. The mains voltage is selectable at either 115 or 230V ac. SD3 is a complete stepper motor and drive solution available with 2.5A and 6.8A outputs for 3-phase stepper motors up to 19.7 Nm. The product line has now been extended by two new device types with integrated fieldbus technology: CANopen (communication profile DS 301, device profile DSP 402) and Modbus (RTU protocol) or with Profibus (DP V0). An RS 442 interface is available to support electronic gearing. Both point-to-point and velocity-profile operating modes are configurable via the fieldbus. Rotation monitoring and the safety function “Safe Stop – Power Removal” are designed to prevent an inadvertent start of the machine for operator safety.