Method for controlling a synchronous electrical machine, corresponding system and motor vehicle comprising the system
A method for controlling a permanent magnet synchronous electrical machine powered by a battery delivering a supply voltage to terminals of the battery, the method including: calculating an initial direct voltage component Vdc and an initial quadratic voltage component in a rotating reference; checking a saturation condition; calculating an angle α of a formula; generating voltages to be applied to the electrical machine if α varies negatively and Vdc is positive or if α varies positively and V dc is negative. The method for example can be applied in a control of synchronous electrical machines.
1. A method for controlling a synchronous electrical machine with a permanent magnet powered by a battery delivering a power supply voltage at its terminals, the method comprising:
computing, via processing circuitry, an initial direct voltage component Vdc and an initial quadratic voltage component Vqc in a revolving reference frame having a plurality of axes;
verifying, via the processing circuitry, a saturation condition by verifying, in an orthogonal reference frame having the direct voltage components for X-axis and the quadratic voltage components for Y-axis, that a point of coordinates Vdc and Vqc is outside of a range dependent on Vbat and delimited by a contour, Vbat denoting a power supply voltage at terminals of the battery;
computing, when the saturation condition is verified and via the processing circuitry, an angle
α
=
arctan
(
Vqc
Vdc
)
;
generating, via the battery and when the saturation condition is verified and if α varies negatively and Vdc is positive or if α varies positively and Vdc is negative, a direct axis voltage and quadratic axis voltage by determining a point of intersection between the contour and a straight line passing through the origin of the orthogonal reference frame and the point of coordinates Vdc and Vqc, the direct axis voltage corresponding to the X-axis of the intersection and the quadratic axis voltage corresponding to the Y-axis of the intersection; and
applying to the electrical machine, via the battery and based on the saturation condition, Vdc and α, one of Vdc and Vqc, direct axis voltage and quadratic axis voltage, and a preceding direct axis voltage and preceding quadratic axis voltage.
2. The method as claimed in claim 1 , wherein
the verification of a saturation condition includes a comparison between √{square root over (Vdc 2 +Vqc 2 )} and
Vbat
3
.
3. The method as claimed in claim 2 , wherein the direct axis voltage to be applied is equal to
Vbat
3
cos
(
α
)
and the quadratic axis voltage to be applied is equal to
Vbat
3
sin
(
α
)
if α varies negatively and Vdc is positive or if α varies positively and Vdc is negative.
4. The method as claimed in claim 1 , further comprising:
applying, via the battery and when the saturation condition is not satisfied, the initial direct voltage component Vdc and the initial quadratic voltage component Vqc to the electrical machine; and
applying, via the battery and if α varies negatively and Vdc is positive or if α varies positively and Vdc is negative, the direct axis voltage and quadratic axis voltage to the electrical machine, and if not, applying a preceding direct axis voltage and preceding quadratic axis voltage to the electrical machine.
5. A system for controlling a synchronous electrical machine with permanent magnet, the system comprising:
processing circuitry
configured to compute, at an instant, an initial direct voltage component Vdc and an initial quadratic voltage component Vqc in a revolving reference frame having a plurality of axes,
configured to verify a saturation condition by verifying, in an orthogonal reference frame having the direct voltage components for X-axis and the quadratic voltage components for Y-axis, that a point of coordinates Vdc and Vqc is outside of a range dependent on Vbat and delimited by a contour, Vbat denoting a power supply voltage at terminals of the battery configured to compute an angle
α
=
arctan
(
Vqc
Vdc
)
if the saturation condition is verified, and
a battery configured to
power the permanent magnet of the electrical machine and configured to generate, when the saturation condition is verified and if α varies negatively and Vdc is positive or if α varies positively and Vdc is negative, a direct axis voltage and quadratic axis voltage to be applied to the electrical machine by determining a point of intersection between the contour and a straight line passing through the origin of the orthogonal reference frame and the point of coordinates Vdc and Vqc, the direct axis voltage corresponding to the X-axis of the intersection and the quadratic axis voltage corresponding to the Y-axis of the intersection, and
apply to the electrical machine, based on the saturation condition, Vdc and α, one of Vdc and Vqc, direct axis voltage and quadratic axis voltage, and a preceding direct axis voltage and preceding quadratic axis voltage.
6. The system as claimed in claim 5 , wherein the processing circuitry is configured to verify the saturation condition by comparing √{square root over (Vdc 2 +Vqc 2 )} and
Vbat
3
.
7. The system as claimed in claim 6 , wherein the direct axis voltage is equal to
Vbat
3
cos
(
α
)
and the quadratic axis voltage is equal to
Vbat
3
sin
(
α
)
,
if α varies negatively and Vdc is positive or if α varies positively and Vdc is negative.
8. A motor vehicle with electric or hybrid drive comprising:
a synchronous machine with permanent magnet and the machine control system as claimed in claim 5 .