Method for synchronizing a synchronous reluctance electric machine

A method of synchronizing a synchronous reluctance electric machine wherein the machine has no speed and/or residual magnetization voltage sensor and includes power terminals and rotating masses whose mechanical rotation frequency is subjected to speed transients caused by power cut-off conditions. The method includes at least one step of applying a control voltage with predetermined amplitude and duration to the terminals after the transients, and one step of detecting the electric current induced by the control voltage, the current induced by the voltage having a harmonic spectrum variable according to the frequency differential between the frequency of the control voltage and the mechanical rotation frequency of the rotating masses, to restore power and synchronous rotation control of the machine.