Control system for a motor

Control system for a d.c. motor (10) of the type comprising a rotor and a stator, a coil assembly having a plurality of coils and a magnetic circuit, one integral with the rotor and the other with the stator, the rotor being driven in rotation by an electric current passing through the coils, and powered by a control system (14) comprising:

• a position detector (30, 32) co-operating with the rotor;
• a power supply circuit (34) to apply to the terminals of the coils a supply voltage to generate the electric current, and
• a control circuit (36),
• with a view to enabling a moving part (24), actuated by said motor (10) and the movement of which is measured by said detector (30, 32), to reach a target position Pc defined by a number of steps dc to be executed;
• characterized in that, during a positioning phase, the control circuit (36), performs the following operations
• determining the number of steps (d) to be executed to reach the target position Pc;
• determining the number of steps executed (c) by applying a pulse (la) delivering a known enemy (Eao);
• determining the drive energy (Ep) and braking energy (Ef) to be supplied by a positioning pulse (Ip) and a braking pulse (If) respectively to reach said target position Pc;
• and
• controlling the power supply circuit (34) for applying the determined positioning pulses (Ip) and braking pulses (If) to said motor (10)
• short-circuits said coils until stoppage is observed by said detector (30, 32),
• comparing the stoppage position with the target position Pc and,
• if the target position Pc has not been reached, starting a new cycle by applying a voltage across the terminals of said coils via the power supply circuit (34).