Modulator for injecting signals into a polyphase power transmission system

Claim 1

Apparatus for generating periodic control signals and for injecting these control signals into an electric polyphase power line having N phases, comprising: a power supply for supplying a direct current between a first and a second supply terminal; means for generating said control signals by controlled commutation of said DC power supply, comprising N bridge circuits, mounted in parallel between the first and second supply terminal, each bridge including two half-bridges and each half-bridge including: two loops mounted in series between these supply terminals and connected at a centrepoint of an inductance common to those two loops; at least one capacitive element mounted in parallel with each loop, each loop including a component with controlled conduction mounted in series with the inductance and polarized from the first supply terminal towards the second; a resistive element associated with each half-bridge mounted between said centrepoint and one of said supply terminals, for dissipating energy stored in said inductance, and a diode, polarized from the second terminal towards the first and connected in series with said resistive element; wherein said components with controlled conduction belonging to the same half-bridge are controlled in phase opposition and wherein the components with controlled conduction belonging to two respective loops of the first and second half-bridges, which are connected to different supply terminals, are controlled with a phase shift in order to generate said periodic control signals; and N output circuits for injecting said control signals into said power line, each output circuit being connected between the centrepoints of two of said inductances belonging respectively to a first and second half-bridge of a same bridge, wherein said energy dissipating resistive element is common to at least two of said bridges.