Device for controlling an electromechanical actuator

• US 20090021196A1
• Filed: 01/22/2008
• Published: 01/22/2009
• Est. Priority Date: 01/24/2007
• Status: Active Grant

• Current Assignee: Airbus Operations SAS (Airbus SE)
• Original Assignee: Airbus France
• Inventors: Rousset, David, Peyras, Laurent
• Granted Patent: US 7,911,165 B2
• Time in Patent Office: Days
• US Class Current: 318/400.20
• CPC Class Codes: H02P 21/06 Rotor flux based control involving the use of rotor position or rotor speed sensors

Abstract

A device for controlling an electromechanical actuator includes an electric motor and an actuator operated by the electric motor. It also includes a digital signal processor (DSP) providing data of reference voltages (Ud_—ffw, Uq_—ffw) on the basis of an decoupled electrical model of the motors. The processor has at least one Park transformation module receiving measurement data for the currents of at least two supply phases of the motor (i_mot_2, i_mot_3) and a datum for the estimated angle of the motor (θ_estimated) and transforming them into data regarding the component of current with stator current axis (id) and the component of current in quadrature with the stator current (iq).

Claims

1. Device for controlling an electromechanical actuator comprising an electric motor and an actuator operated by the electric motor, characterized in that it comprises a digital signal processor (DSP) providing data of reference voltages (Ud_—

ffw, Uq<sub>—

ffw</sub>) on the basis of an decoupled electrical model of the motor, the processor comprising at least one Park transformation module receiving measurement data for the currents of at least two supply phases of the motor (i_mot_2, i_mot_3) and a datum for the estimated angle of the motor (θ

_estimated) and transforming them into data regarding the component of current with stator current axis (id) and the component of current in quadrature with the stator current (iq<sub>—

ref</sub>), a module for comparing these data with reference values of current with stator current axis (id<sub>—

ref</sub>) and of current in quadrature with the stator current (iq_ref) providing, through integral proportional correctors (IP) data for the voltage variation (del_Ud, del_Uq), the voltage variation data being combined with the reference voltage data (Ud<sub>—

ffw</sub>, Uq<sub>—

ffw</sub>) at the input of a vector regulation module operating an inverter for supplying the motor with pulses of modulated width.

2. Device according to claim 1 wherein the inverter is a three-arm inverter, the vector regulation module operating this inverter through six principal vectors phase shifted with respect to one another by 60°

and thus forming six sectors.

3. Device according to claim 2 for which each of the vectors corresponds to a sequence composed of three logic variables which instantaneously operate the three arms of the inverter.

4. Device according to claim 1, for which the reference current value (id_—

ref) with stator current axis is generated, through a regulator module of integral proportional type part of the DSP, on the basis of modulation data of the inverter (mod<sub>—

amp</sub>, m<sub>—

a—</sub>

max).

5. Device according to claim 4, for which the regulator is adapted for delivering a value of current with reference stator current axis (id_—

ref) constituting a control for reducing the flux of the motor for a motor supply voltage U_S greater than or equal to the nominal voltage of the motor U_SMAX and a zero value for a supply voltage below the nominal voltage.

6. Device according to claim 1, wherein the DSP comprises a module for controlling the electric motor comprising a torque control block and a speed control block that are alternatively selectable and deliver a reference quadrature current value (iq_reference).

7. Device according to claim 6, for which the torque control block comprises an integral-proportional type corrector 13 receiving data regarding the reference torque and number of poles of the motor and delivering, when it is selected, the reference quadrature current value.

8. Device according to claim 6, for which the speed control block comprises an integral-proportional type corrector 14 receiving a datum regarding the comparison of a reference angular speed (ω

_ref) and an estimated angular speed (ω

_estimated) and delivering, when it is selected, the reference quadrature current value.

9. Device according to claim 6, for which at least one of the blocks comprises a device for limiting the current value between two extreme values (iq_max, −

iq_max).

10. Device according to one claim 1, further comprising a module for calculating a direct current absorbed by the inverter (I_DC), receiving data regarding temperature, supply voltage of the inverter (U_DC) and counterelectromotive force of the motor (E₀) receiving moreover the data regarding the component of current with stator current axis (Id) and the component of current in quadrature (Iq) with the stator current, and comprising means for calculating, on the basis of these data, power losses due to the control components of the motor (P_loss) and mechanical power restored by the motor (P_MEC), this calculation module furthermore comprising means for calculating said current absorbed (I_DC) on the basis of the ratio of the sum of said powers and the supply voltage of the inverter (U_DC).

11. Device according to claim 10, characterized in that it comprises a module for limiting said current absorbed providing a limited value of direct current absorbed by the inverter (I_{DC lim}).

12. Device according to claim 6 further comprising a summater of the reference quadrature current value (Iq_reference) and of the limited value of direct current absorbed by the inverter (I_{DC lim}) so as to provide a limited quadrature current value (Iq_ref_limited).

13. Device according to claim 1, further comprising a module for reconstructing the speed and the position of the motor on the basis of at least two data regarding voltage measurements between supply phases of the motor (U_mot23, U_mot31) and data relating to the measurement of the currents of at least two supply phases of the motor (I_mot—

2, I<sub>mot—

3</sub>), the reconstruction module comprising a Park transformation block providing data regarding voltage with stator axis (Vd_fb) and quadrature (Vq_fb) on the basis of the voltage measurement data (U_mot23, U_{mot 31}), and a feedback datum regarding the estimated angle of the motor (θ

_estimated), a calculation unit carrying out by iterative calculations, on the basis of the stator axis and quadrature voltage data as well as of the stator axis and quadrature current data, the calculation of the estimated angular speed of rotation (ω

_estimated) of the motor and by integration the calculation of the estimated angle (θ

_estimated) of the motor.

14. Device according to claim 1, for which the electric motor is a brushless multipole three-phase motor.

15. System of electromechanical actuators, such as an electrically controlled braking system, comprising a control device according to claim 1.

16. Aircraft equipped with a braking system according to claim 15.