A device for checking the operation of a power module, the power module comprising an input for an input DC voltage (Vcc) and an energy conversion circuit for three phases, the conversion circuit comprising three conversion branches (B1, B2, B3) connected in parallel to the terminals of the input, each conversion branch (B1, B2, B3) comprising two sets of components connected in series with each other, each set comprising at least one switch with a diode connected in antiparallel, the checking device comprising: a. an upstream module intended to be connected to the terminals of the input of the power module, the upstream module comprising a first power source having a voltage greater than or equal to a first voltage terminal and a current less than or equal to a first current terminal, b. a tool branch comprising two sets of components connected in series with each other, each set comprising at least one switch with a diode connected in antiparallel, the tool branch being intended to be connected in parallel to the terminals of the input of the power module, c. a downstream module connected, on the one hand, to the mid-point (M1, M2, M3) between the two sets of components of the tool branch and intended to be connected, on the other hand, to the mid-point (M1, M2, M3) between the two sets of components of one of the conversion branches (B1, B2, B3), referred to as the branch being tested, so as to form a current loop, the downstream module comprising a second power source having a voltage strictly lower than a second voltage terminal and a current strictly higher than a second current terminal, d. a control module configured to control the switches of the tool branch and the branch being tested according to a series of predetermined configurations, e. a measurement module configured to measure the current in the current loop over time, and f. a checking module configured to check the operation of the branch being tested as a function of the current measured over time by the measurement module. a. an upstream module intended to be connected to the terminals of the input of the power module, the upstream module comprising a first power source having a voltage greater than or equal to a first voltage terminal and a current less than or equal to a first current terminal, b. a tool branch comprising two sets of components connected in series with each other, each set comprising at least one switch with a diode connected in antiparallel, the tool branch being intended to be connected in parallel to the terminals of the input of the power module, c. a downstream module connected, on the one hand, to the mid-point (M1, M2, M3) between the two sets of components of the tool branch and intended to be connected, on the other hand, to the mid-point (M1, M2, M3) between the two sets of components of one of the conversion branches (B1, B2, B3), referred to as the branch being tested, so as to form a current loop, the downstream module comprising a second power source having a voltage strictly lower than a second voltage terminal and a current strictly higher than a second current terminal, d. a control module configured to control the switches of the tool branch and the branch being tested according to a series of predetermined configurations, e. a measurement module configured to measure the current in the current loop over time, and f. a checking module configured to check the operation of the branch being tested as a function of the current measured over time by the measurement module.