Method for estimating the position of a rotor of a synchronous electrical machine

1. A method for estimating the position of a rotor of a synchronous electrical machine without the injection of signals, comprising a rotor and a stator coupled to an inverted synchronous electrical machine, acting as exciter, via a rectifier, the rectifier being connected to the stator of the inverted synchronous electrical machine and to the rotor excitation of the main machine, the estimation method comprising the following steps:

a. measurement of a current i abc circulating in the stator of the synchronous electrical machine;

b. determination of two signals in quadrature i α ; i β according to a stationary reference frame from the current i abc and isolation of two filtered signals i αh ; i βh from the two signals in quadrature i α ; i β ;

c. demodulation of the two filtered signals i αh ; i βh in order to obtain two demodulated signals i αobs , i βobs , the step of demodulation of the two filtered signals i αh ; i βh using a measurement of a current i ex of the stator of the inverted synchronous electrical machine;

d. obtaining of an estimated position {circumflex over (θ)} of the rotor from the two demodulated signals i αobs , i βobs .

2. The estimation method according to claim 1 , wherein the estimated position {circumflex over (θ)} estimated in the step d is made according to the following mathematical expression:

θ

ˆ

=

atan

⁡

(

i

β

⁢

obs

i

α

⁢

obs

)

.

3. The estimation method according to claim 2 , comprising a step of estimation of the speed {dot over ({circumflex over (θ)})} of the rotor of the synchronous electrical machine from the estimated position {circumflex over (θ)} of the rotor of the synchronous electrical machine.

4. The estimation method according to claim 3 , comprising a step of isolation with anticipative action of the two filtered signals i αh ; i βh from the two signals in quadrature i α ; i β and a phase of a filtered speed {dot over ({circumflex over (θ)})} f of the rotor, the filtered speed {dot over ({circumflex over (θ)})} f of the rotor representing the speed {dot over ({circumflex over (θ)})} of the rotor when filtered.

5. The estimation method according to claim 1 , wherein the estimated position {circumflex over (θ)} estimated in the step d is done using an observer.

6. The estimation method according to claim 1 , wherein the two filtered signals i αh ; i βh have a frequency combining an operating frequency f ex of the inverted synchronous electrical machine and a frequency f e of the synchronous electrical machine according to the following formula:

f e− + n*f ex

wherein n represents an even relative integer number.

7. The estimation method according to claim 1 , wherein the isolation of the two filtered signals i αh ; i βh from the two signals in quadrature i α ; i β is performed using a bandpass filter or a high-pass filter.

8. The estimation method according to claim 1 , comprising a step of filtering of the two demodulated signals i αobs , i βobs between the step c and the step d, the filtering step being performed using a bandpass filter or an extended Kalman filter.

9. The estimation method according to claim 1 , comprising a step of correction of the estimated position {circumflex over (θ)} with the following mathematical formula:

{circumflex over (θ)} corr ={circumflex over (θ)}+{circumflex over (ϕ)} corr

wherein {circumflex over (ϕ)} corr is a correction of the delays on the estimation of the position and {circumflex over (θ)} corr is a corrected position of the rotor of the synchronous electrical machine.

10. The estimation method according to claim 9 , wherein the correction of the delays {circumflex over (ϕ)} corr is the sum of a phase-shift correction of the filters used {circumflex over (ϕ)} F in the estimation method and of a phase-shift correction dependent on the electromagnetic characteristics of the synchronous electrical machine {circumflex over (ϕ)} LC .

11. The estimation method according to claim 1 , the estimation method being able to be repeated periodically, wherein the demodulation step is preceded by a step of evaluation of a phase {circumflex over (ϕ)} of a carrier from the filtered signals i α h ; i β h , of an angular frequency ω ex of the inverted synchronous electrical machine and of the estimated position {circumflex over (θ)} in a preceding iteration of the estimation method, the carrier being obtained at the rotor of the inverted synchronous electrical machine.

12. A device for estimating the position of a rotor of a synchronous electrical machine coupled to an inverted synchronous electrical machine via a rectifier for operation when stopped or at low speed according to one of the preceding claims, comprising:

a) a module for measuring a current i abc circulating in the stator of the synchronous electrical machine;

b) a module for determining and isolating harmonics of two filtered signals i αh ; i βh from the current i abc ;

c) a module for demodulating the two filtered signals i αh ; i βh from a measurement of the current i ex of the stator of the inverted synchronous electrical machine or of a carrier of angular frequency ω ex of the inverted synchronous electrical machine in order to obtain two demodulated signals i αobs , i βobs ;

d) an obtaining module configured to determine an estimated position {circumflex over (θ)} of the rotor of the synchronous electrical machine from the two demodulated signals i αobs , i βobs .

13. An electrical machine comprising an inverted electrical machine and at least one synchronous electrical machine equipped with the estimation device according to claim 12 .