Stepper drives receive step and direction signals within a stepper motor, which is a synchronous, brushless, polyphaser motor. In this type of control system, the indexer or positioning control will send such pulses to the higher voltage drive in order to be converted into electrical signals for the stepper motor. The drive thus integrates feedback on speed and torque that allows for optimal motor performance.
Performance can be measured by the flow of current from the stepper drive to the motor winding, with higher outputs resulting from higher levels of torque rather than speed. In delivering effective commutation, though, stepper drives should be current-limited in order to provide motor protection. They are also limited by the need for a pulse for every step of the motor shaft, as rotation speed is directly proportional to pulse frequency. Some drives even include an on-board oscillator to support external analogs.
These drives are generally comprised of an electric motor and speed controller that communicate in order to adjust operating speeds. However, they can also consist of a constant-speed motor and continuously adjustable speed-changing device. Both set-ups are invested in energy conservation and process control, from smooth and accurate operation to acceleration control, variable compensation, and production rate adjustment. Other variations include drives for AC and DC motors, hydraulic systems, continuously variable transmissions, traction drives focused on speed ratios, and eddy current drives that merge a fixed speed motor and clutch.
Stepper Drives supplied by MCMA Member Companies