SimElectronics 1.3

Controlled Stepper Motor

This model demonstrates how to use the Stepper Motor Driver and Stepper Motor blocks together to implement a controlled permanent magnet stepper motor. The model provides two controller options: one to control position and one to control speed. To change the controller type, right-click on the Stepper Controller block, select Block Choice and then the desired controller.

The stepper has a full step size of 1.8 degrees. In position control, Vref = +5V corresponds to 100 steps i.e. 180 degrees. Hence if Vref = +0.5V, the demanded angle is 18 degrees. In speed control, Vref = +5V corresponds to 100 steps per second. Hence if Vref = +0.5V, in one second the motor steps through 18 degrees.

This model is a system-level model suitable for studying the dynamics of the stepper and whether step angle will slip when driving a given load. It can also be used to tune the stepper controller to improve stepping performance. Often the controller is either partly or fully implemented on an off-the-shelf stepper controller module. This demo reverse engineers such a module at a system-level.

The alternative of implementing the algorithm on a microprocessor (such as a PIC or xPC) gives greater flexibility, and the microprocessor may also be used to control other parts of the overall system. In this case parts of the Stepper Motor Driver block may also be implemented in on the microprocessor, leaving only the power amplifier stage in analog electronics.

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