Patent ID: 11888431
Assignee: STMICROELECTRONICS S.R.L.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A method, comprising:
driving an electric motor having a set of motor windings in a pulse width modulation (PWM) mode comprising applying PWM signals to the motor windings in the set of motor windings of the electric motor;
setting a finite time length value of a time window having a finite length in time,
selecting a motor winding in the set of motor windings of the electric motor and driving the selected motor winding in the set of motor windings of the electric motor to be in a tri-state during a time interval having a time length equal to the set time length value of the time window;
sensing a zero-crossing (ZC) of an oscillating back electromotive force induced in the motor winding during the time window in which the motor winding is in the tri-state and producing a ZC sensing signal as a result, the ZC sensing signal having a first edge at a first time instant at the sensed ZC and a second edge at a second time instant that is separated from the first time instant by a half oscillation of the oscillating back electromotive force;
detecting a phase of a current flowing in the selected motor winding at a time instant that is time-shifted by a time shift with respect to the second time instant of the second edge of the ZC sensing signal; and
adjusting the finite time length value of the time window based on the detected phase of the current.