Interface for supplying power to a load from an electrical power supply network

The power supply interface includes a rectification stage, having an autotransformer connected to a power supply network, and a signal conditioning stage having an output supplying power to a load. The conditioning stage includes a power module, for conditioning the power supply signal, and a control module designed to control the power module. An autotransformer includes at least one additional winding (A, B, C; A, B, C) connected to the control module to supply it with electrical power, the or each additional winding being magnetically coupled to at least one primary winding (A, B, C) of the autotransformer. The power is supplied to a motor in an airplane.