Electric Drive Dead Zone & Compensation

The 'dead zone' is a characteristic of electric drives that puts a limit on the minimum amount of torque needed for rotational speed of the driveshaft. It is, on a torque/speed curve, a region where no rotational speed exists for a torque not equal to zero. The dead zone is modeled graphically as shown below.

When an electric drive is modeled exhibiting dead zone characteristics, the torque from the electric drive is delayed in time from an electric drive not exhibiting these same characteristics.

Dead zone non-linearity affects systems which use electric drives and this discontinuity must be compensated for in some way. One such way of compensating for dead zone works best if the system physics are well-known and the system's model does not inherently change with respect to time. A system with nonzero velocity that enters the deadzone region will coast to a stop at some distance. Knowing the desired position of the system and the velocity at which the system entered the dead zone region, the distance that the system coasts can be measured and applied as a correction to the desired input. Over multiple iterations at varying velocities, a compensation table can be created that will compensate for the coasting caused by the dead zone nonlinearity. This table can be constructed by measuring the required states and programming a fuzzy logic controller to correct the input.

A system model is being constructed in Simulink and results will be posted as they are achieved.