Sensorless Rotor Velocity Tracking
Controller for the Permanent Magnet
In this paper, we present a sensorless rotor velocity tracking
controller for the full order, nonlinear dynamic model of the
permanent magent stepper motor. We design a volatge control
strategy in conjunction with an open-loop position estimation
scheme that achieves global exponential rotor velocity/phase
current tracking and only requires phase current measurements.
Experimental results are included to demonstrate the efficacy of
the proposed algorithm.
Our objective is to design a sensorless, singularity free
controller for the full-order, nonlinear dynamic model of a stepper
motor, to obtain rotor velocity tracking.The control algorithm does
require measurement of stator currents, however, to estimate the
rotor position and velocity.
The overall control strategy is formulated at the voltage level,
the physical input to an electric motor. However, as characteristic
of the integrator backstepping approach, intermediate or embedded
control signals are formulated. The integrator backstepping
approach will require that a control signal is generated for the
output subsytem, i.e., the rotor velocity in the mechanical
subsytem. Next, this control signal is propagated back through the
connected subsystems, the electrical subsystems, until a controller
is formulated for the system inputs, the input voltages.Following
this approach, we develop a desired torque trajectory for the
mechanical subsystem. Specifically, this trajectory would ensure
rotor velocity tracking if applied directly to the mechanical
subsystem. Subsequently, we design the desired phase current
trajectories to ensure that the desired torque is delivered to the
mechanical subsystem. The stator voltage control inputs are then
designed to guarantee that phase current tracking is achieved.
Lastly, a Lyapunov-like stability analysis is performed to examine
the stability of the overall closed-loop system.
Some Experimental Results:
Select and click to view some of the experimental plots:
For more information concerning this research, please refer to
the following publication:
A. Behal, M. Feemster, D. M. Dawson, and A. Mangal, "Sensorless
Rotor Velocity Tracking Controller for the Permanent Magnet Stepper
Motor'', Proc. of the IEEE Conference on Control
Applications, Anchorage, AK, pp. 150-155, September 2000.