Control arrangement for permanent magnet machines

摘要

In a control arrangement for a permanent magnet machine comprising multiple windings (3, Fig. 1) that are energised sinusoidally in a phased relationship so as to create a rotating field that interacts with the magnets (N, S) to produce an output torque, energisation of each winding (3) is controlled by a separate switching circuit 4 under the control of a controller 5 which controls all of the switching circuits 4, and each switching circuit 4 has a current sensor 12 which produces a sensor signal indicative of the operational state of the switching circuit 4 and which is compared by the controller 5 with predetermined sensor signals in a memory 15 so that the controller 5 varies operation of the switching circuits 4 dependent on variations of the sensor signals from the predetermined sensor signals. Each switching circuit 4 may comprise an H-bridge converter, and the current sensor 12 located to sense flywheeling currents around the bridge. The memory device 15 may incorporate a look-up table based on any analysis of the possible fault conditions that may occur and the appropriate control actions required in the switching circuits 14.