Device for the detection of an angle of rotation of a brushless multi-phase d.c. motor

A drive system comprising:

• a multi-phase d.c. motor having a permanent magnet rotor and a stator which includes a plurality of windings, and a device for detecting an angle of rotation of the rotor with respect to the stator, the detecting device comprising;
• drive means for applying electric test pulses to the windings while the rotor does not rotate, a measurement circuit for detecting flyback pulses generated by the motor in response to the test pulses, and a processing unit which processes the durations of the detected flyback pulses in combination in order to determine said angle of rotation.

In a brushless multi-phase d.c. motor having a permanent magnet rotor and a stator with multiple windings, a method for determining the position of the rotor with respect to the stator while the rotor is at standstill, comprising:

• applying short duration electric test pulses to the windings without rotation of the rotor, detecting flyback pulses generated in the stator windings in response to said test pulses,
• processing detected flyback pulses in combination on the basis of the durations thereof so as to determine the rotor position relative to the stator, and
• applying recurrent drive signals to the stator windings in a given sequence to rotate the rotor in a predetermined direction of rotation on the basis of the determined rotor position.