A field modulated electromagnetic clutch with slip control

This paper presents the control of an electromagnetic clutch. The considered clutch is particularly based on the modulated field principle and has two shafts with speed ratio of 1.14 at synchronous conditions. The clutch engagement and disengagement and torque transmission is controlled by manipulation of the stator currents and the slip speed between the two shafts. The dynamic model of the electromagnetic clutch is found to be nearly identical to that of a permanent magnet synchronous machine, however the electrical speed is replaced by the slip speed. The relationship between the torque transmission between the input and output shafts and the electrical power input is explained. A clutch control strategy based on the d-q current control is presented. The test bed setup with the experimental prototype electromagnetic clutch is presented and the simulation results for this prototype is presented. It is shown that the electrical power demanded by the clutch is high only during engagement and disengagement transient periods and the steady state power is only required to compensate the electrical losses in the clutch. Experimental results demonstrate the controllability of the clutch with the proposed strategy.