A variable speed drive for a three-phase electric motor, including a rectifier module supplying a rectified voltage from a single-phase alternating current network, a voltage step-up module supplying a regulated bus voltage, and an inverter module supplying a control voltage to the motor. The variable speed drive includes a hybrid power-factor correction device that drives the voltage step-up module and that includes a digital circuit including a voltage step-up module supplying a correction signal based on a measurement signal of the bus voltage and an analog circuit supplying a driver signal to the step-up module based on a measurement signal of the rectified voltage and based on the correction signal.