Step motors are receiving wide attention in industrial applications which require high performance. They are used in open loop control of position and translation motion but have poor performance. This paper discusses open loop control using field orientation of step motors to improve its dynamic performance. A simplified mathematical model of two phase variable reluctance (VR) stepper motor is introduced. Advance turn-on and advance turn-off is presented to obtain the optimal control angle in order to decrease phase current rise time, produce maximum torque per ampere, elimination of negative torque region, reducing motor losses, and increasing motor efficiency. A drive circuit for two phase VR step motor is implemented. The simulation results of stator current are compared to the experimental results. |
