Mechanically commutated self control of PM- synchronous machines

In this paper a new method and device is presented that enables a PM-motor to be directly powered with an electrical DC backup source. The presented method uses discrete voltage vectors for motor control as they are well known from Direct Torque Control and Direct Self Control (DSC). The most distinctive difference of the presented method is that it works via a mechanical commutator device without any micro- or power electronics. In opposition to DTC and DSC where flux and torque are controlling the selection of voltage states, the presented method uses the mechanical rotor position to control the discrete voltage vectors. Based on that, the presented method is called MCSC, which means mechanically commutated self control. A simple and robust construction of the commutation device guarantees a low failure probability and the possible integration into the motor housing. Only in emergency case the commutator is activated for a short period of time in order to move the motor into a safe position, stopped with limit switches. Therefore the device can be designed for motors lifetime although carbon brushes are used and a regular maintenance is not necessary as it is known from brushed DC machines.