Method for detecting the presence or absence of a neutral conductive line in a multiphase ac voltage source

A method, implemented by a system for controlling a two-way synchronous rectifier connected to a multi-phase AC voltage source, for detecting the presence or the absence of a neutral conductive line in the multi-phase AC voltage source, the two-way synchronous rectifier comprising a neutral input terminal able to be connected to a neutral conductive line of the multi-phase AC voltage source, an active power factor correction stage and a DC voltage bus connected at the output of the active power factor correction stage, the active power factor correction stage being provided with a plurality of switching electronic branches, at least one half-branch of each of the switching electronic branches comprising at least one switching component, the number of switching electronic branches being equal to the number of phases in the multi-phase AC voltage source, the DC voltage bus comprising two half-branches connected in series at an intermediate terminal, said intermediate terminal being connected to the neutral input terminal, the control system comprising means for measuring at least one quantity relating to a current able to flow in the DC voltage bus, the method comprising:

• a step of measuring at least one first quantity relating to a current flowing in the DC voltage bus at the end of a pre-charging phase of the two-way synchronous rectifier, during which phase no switching component is controlled by the control system, said measuring step providing a first measured quantity;
• a step of receiving at least one second measured quantity at the end of the pre-charging phase of the two-way synchronous rectifier;
• a step of comparing said at least one first measured quantity to a threshold value based on said at least one second measured quantity;
• and
• depending on the result of the comparison, a step of detecting the presence or the absence of a neutral conductive line in the multi-phase AC voltage source, and
• said at least one first measured quantity is the amplitude and/or the frequency of the voltage in the DC voltage bus at the end of the pre-charging phase of the two-way synchronous rectifier, and
• said at least one second measured quantity is the effective amplitude Ueff1 and/or the frequency f1 of the voltage provided by the multi-phase AC voltage source at the end of the pre-charging phase of the two-way synchronous rectifier, with said at least one second measured quantity being provided by a third-party measurement system.