Control of a permanent-magnet electric machine
View Patent ↗A method of controlling a permanent magnet synchronous machine including a stator and a rotor. The method includes determining an estimated position of the rotor, and determining a second in-phase voltage setpoint that, in alternation, is equal either to a first in-phase voltage setpoint or else to the first in-phase voltage setpoint plus a predetermined periodic signal. The determining an estimated position of the rotor includes determining a coupling term, determining a speed of rotation of the rotor as a function of the coupling term, and determining the estimated position of the rotor by integrating the speed of rotation of the rotor.
1. A control method for controlling a permanent magnet synchronous machine including a stator and a rotor, the method comprising:
determining an estimated position of the rotor;
determining an in-phase current and a quadrature current as a function of stator currents and of the estimated position of the rotor;
determining a first in-phase voltage setpoint and a quadrature voltage setpoint as a function of the in-phase current, of the quadrature current, of an in-phase current setpoint, and of a quadrature current setpoint;
determining a second in-phase voltage setpoint that is equal in alternation either to the first in-phase voltage setpoint or to the first in-phase voltage setpoint plus a predetermined periodic signal;
determining stator voltage setpoints as a function of the second in-phase voltage setpoint, of the quadrature voltage setpoint, and of the estimated position of the rotor; and
controlling the synchronous machine as a function of the stator voltage setpoint;
wherein the determining an estimated position of the rotor comprises:
determining a coupling term as a function of a difference between the quadrature current when the second in-phase voltage setpoint is equal to the first in-phase voltage setpoint and the quadrature current when the second in-phase voltage setpoint is equal to the first in-phase voltage setpoint plus the predetermined periodic signal;
determining a speed of rotation of the rotor as a function of the coupling term; and
determining the estimated position of the rotor by integrating the speed of rotation of the rotor.
2. A control method according to claim 1 , wherein the determining a speed of rotation of the rotor as a function of the coupling term includes using a corrector for canceling the coupling term.
3. A control method according to claim 1 , wherein the predetermined periodic signal is a pulse signal.
4. A control method according to claim 1 , wherein the controlling the synchronous machine as a function of the stator voltage setpoint comprises delivering the stator voltage setpoint to a pulse width modulated inverter presenting a predetermined period, the second in-phase voltage setpoint being equal to the first in-phase voltage setpoint plus the predetermined periodic signal for one to three periods of the pulse width modulation, once every 15 to 25 periods.
5. A control method according to claim 1 , wherein the rotor is a salient pole rotor.
6. A control method according to claim 1 , wherein the rotor is a smooth rotor, the method further comprising saturating stator teeth facing poles of the rotor.
7. A non-transitory computer readable medium including a computer program including instructions for performing a control method according to claim 1 when the program is executed by a computer.
8. A control unit for controlling a permanent magnet synchronous machine having a stator and a rotor, the control unit comprising:
means for determining an estimated position of the rotor;
a module for determining an in-phase current and a quadrature current as a function of stator currents and of the estimated position of the rotor;
a module for determining a first in-phase voltage setpoint and a quadrature voltage setpoint as a function of the in-phase current, of the quadrature current, of an in-phase current setpoint, and of a quadrature current setpoint;
a module for determining a second in-phase voltage setpoint that is equal in alternation either to the first in-phase voltage setpoint or to the first in-phase voltage setpoint plus a predetermined periodic signal;
a module for determining stator voltage setpoints as a function of the second in-phase voltage setpoint, of the quadrature voltage setpoint, and of the estimated position of the rotor; and
control means for controlling the synchronous machine as a function of the stator voltage setpoint;
wherein the means for determining an estimated position of the rotor comprises:
a module for determining a coupling term as a function of a difference between the quadrature current when the second in-phase voltage setpoint is equal to the first in-phase voltage setpoint and the quadrature current when the second in-phase voltage setpoint is equal to the first in-phase voltage setpoint plus the predetermined periodic signal;
a module for determining a speed of rotation of the rotor as a function of the coupling term; and
a module for determining the estimated position of the rotor by integrating the speed of rotation of the rotor.
9. A control system comprising a control unit according to claim 8 , an inverter, and a synchronous machine.