Integral Sliding Mode Control and Digital Controller Design Using State Space Methods for a Hybrid Stepper Motor: Comparative Study

The hemodialysis is a medical application dedicated to the patient who suffers from a renal insufficiency, with the help of an extracorporeal circuit and an artificial kidney, the device replaces the functioning of the kidney, thanks to a peristaltic pump, the blood is taken, purified and then reinjected into the body of the patient. The application of the stepper motors is widely used, due to its multiple advantages, such as the price, the control with an open loop, etc… the aim of this paper to study the control of the stepper motor in order to apply it to motorize the blood pump of the hemodialysis. We start with a modeling of the motor, development of the equations necessary to calculate the gains of the digital corrector by state control and the parameters of the variable structure controller by integral sliding mode. The simulation of the correctors is done in order to find the appropriate control, two situations are targeted, the simulation with and without load torque. The state space representation is applied to model the regulated system, thus the vector control in the d-q axes is implemented to facilitate the control. Due to the non-linearity of the stepper motor, the speed and position control requires a robust and efficient control, the simulation presents important results in order to interpret them and deduce the main factors to control the motor in a convenient way.