Importance

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Abstract

A brushless electric motor system comprises a rotor and a stator comprising poles. Electrical phase windings have coils (U1-6, V1-6, W1-6) wound around the poles. Power switches (T1-24) controlled by a control device supply electric current the windings from positive and negative rails connected to power supply. For each phase at least one group of four power switches arranged in a H-bridge configuration is provided. The coils of each phase winding are preferably divided into winding group (U1-3, Ua-6, V1-3, V4-6, W1-3, W4-6) and the electric conductor of each winding group is then electrically conductor of the other winding groups. Then four power switches arranged in an H-configuration is provided for each winding group. The use of power switches in H-bridge configurations allows the faulty windings or winding groups to be disabled and that the rest of the windings or coils can be used for driving the rotor, this giving the motor system a high reliability. The current supplied to other windings or winding groups can then be increased to compensate for the faulty group. The coil groups can be separated from other coil groups by unwound stator poles. Current sensors (303) can sense the current in each winding group and be used to detect whether the currents are too high. The sensed currents can be used to identify fault conditions in the system so that then suitable switches can be disabled, disconnecting a faulty winding group.

First Claim