Implementation of two-axis highly accurate position control of space-vector PWM based microstepping bipolar drive

This paper presents a digital implementation of two-axis position control of microstepping bipolar drive with the controlled current, depending on the load torque applied. The topology of power converter for each motor is the conventional three-phase inverter, using space-vector pulse-width-modulation (PWM) technique. It is well known that the microstepping technique allows the stepping motor rotating in a fraction of its full step. In high precision applications, the less fractional step is necessary to achieve this requirement and typically operated at low speeds. Consequently, the currents should also be controlled using PWM during this low speed operation, otherwise the over currents could be happened due to low back EMF. In this paper, the step resolutions can be configurable using zero-order-hold (ZOH) to generate the discrete sinusoidal command voltages with their peaks generated by PI current controller. The overall system of two-axis position control drive system is implemented on a single fixed-point TMS320F2808 digital signal processor (DSP), using object oriented programming (OOP). Experimental results are presented to validate the implementing system.