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Unipolar Stepper Motor Driver

Driver for unipolar stepper motor

Library

Drivers

Description

The Unipolar Stepper Motor Driver block represents a driver specifically configured for use with the Unipolar Stepper Motor block. It connects the two winding center-tap connections A0 and B0 to the positive supply with a voltage equal to the value you provide for the Output voltage amplitude parameter. The A+, A-, B+, and B- ports are grounded in the appropriate sequence to create the stepping motion. The block initiates a step each time the voltage at the PWM port rises above the Enable threshold voltage parameter value.

If the voltage at the REV port is less than or equal to the Reverse threshold voltage parameter value, pulse A leads pulse B by 90 degrees. If the voltage at the REV port is greater than the Reverse threshold voltage value, pulse B leads pulse A by 90 degrees and the motor direction is reversed.

At time zero, A- and B+ are grounded.

If you set the Stepping mode parameter to Half stepping, the Unipolar Stepper Motor Driver block can produce the output waveforms required for half stepping. In this mode, there is an intermediate state between the full steps, in which just one of the A or the B half-windings is powered. As a result, the step size is half of the stepper motor's full step size. At half steps, windings that are not powered are short-circuited. This approximates the effect of a freewheeling diode connected across the windings.

Dialog Box and Parameters

Enable threshold voltage

When the voltage at the PWM port rises above this threshold, the Unipolar Stepper Motor Driver block initiates a step. The default value is 2.5 V.

Reverse threshold voltage

When the voltage at the REV port rises above this threshold, pulse B leads pulse A by 90 degrees, and the motor direction is reversed. The default value is 2.5 V.

Output voltage amplitude

Amplitude of the output pulse trains. The default value is 10 V.

Stepping mode

Select Full stepping or Half stepping. The default value is Full stepping.

Ports

The block has the following ports:

A+

Top A-phase electrical connection

A0

A-phase center tap connection

A-

Lower A-phase electrical connection

B+

Top B-phase electrical connection

B0

B-phase center tap connection

B-

Lower B-phase electrical connection

PWM

Triggering input step voltage

REF

Input floating reference voltage

REV

Input voltage that controls motor direction

See Also

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