Method for the starting and steady-state supply of a permanent-magnet synchronous motor particularly for driving a hydraulic pump

A method for the starting and steady-state supply of a permanent-magnet synchronous motor, particularly for driving a centrifugal hydraulic pump, comprising the following steps:

• a) a learning step, during which the rotor of the motor is turned through two consecutive turns covering 180 mechanical degrees, applying to the stator a DC starting current for the first 180 mechanical degrees and inverting it for the second 180 mechanical degrees after the rotor has reached the first 180 mechanical degrees and storing, by means of a memory that resides in the power supply circuit combined with a linear magnetic position sensor, the operating characteristics in a discrete number of points that correspond to preset angular positions of the rotor, determining, during said learning step, the starting current and the real zero position of the rotor;
• b) a starting step, during which a higher current than the starting current determined during the first step is applied at an initially low frequency which then gradually increases, waiting for and checking, by means of the linear sensor, the transit of the rotor at 80 and 100 mechanical degrees and subsequently at 260 and 280 mechanical degrees;
• c) a steady-state step, during which once the steady-state frequency and therefore the steady-state speed have been reached, the applied current is practically sinusoidal and the rotor is waited for at transit through the zero points before inverting the direction of the current;
• control functions being provided which, if the rotor slows during the steady state step, return the procedure to the starting step and which, in case of jamming of the rotor, reversal of the rotation direction, failure of the linear sensor or anomalies, return the procedure to the learning step.