VARIABLE SPEED DRIVE CONTROL

Examples include a method for controlling a variable speed drive driving an electric motor. The variable speed drive is connected to an electric power source and comprises a passive DC-link and an inverter stage controlled by a first controller of the variable speed drive. The passive DC-link is connected to the inverter stage. The method comprises running the electric motor to reach a steady-state operating point, measuring a plurality of values of current or voltage of the passive DC-link, and computing, by a second controller, a frequency spectrum of the DC-link based on the plurality of values of current or voltage measured. The method further comprises detecting a specific resonance frequency by comparing amplitudes of the frequency spectrum to a predetermined pattern, and modifying filter parameters of a digital filter of the DC-link or control parameters of a control law of the electric motor based on the specific resonance frequency.