Abstract: Examples include a method for controlling a variable speed drive driving a three-phase electric motor. The method includes measuring current signals in the windings of the electric motor, and determining a current parameter associated to the electric motor based on the current signals. The current parameter includes either a current offset of at least one winding of the electric motor in relation to a zero-current value, or a current misbalance between windings of the electric motor. The method further includes determining an amended control law of the electric motor for decreasing the determined current parameter, and applying pulse width modulation signals on insulated gate bipolar transistors of the inverter based on the amended control law.

Abstract: A method for controlling a variable speed drive supplying power to an electric motor, the variable speed drive comprising a plurality of at least Ni low-voltage power cells connected in series, comprising: upon reception of a speed command, determining a number Mi of cells sufficient to supply power to the motor at a target voltage V that is determined based on the speed command; and activating the Mi power cells from among the Ni power cells, and deactivating the Ni-Mi other power cells in order to supply power to the motor in accordance with the speed command.

Abstract: A method for controlling a variable speed drive supplying power to an electric motor, the variable speed drive comprising a plurality of at least Ni low-voltage power cells connected in series, comprising: upon reception of a speed command, determining a number Mi of cells sufficient to supply power to the motor at a target voltage V that is determined based on the speed command; and activating the Mi power cells from among the Ni power cells, and deactivating the Ni-Mi other power cells in order to supply power to the motor in accordance with the speed command.