Device and method for field weakening control of compressor, air conditioner and storage medium

Devices are provided for field weakening control of a compressor, including the compressor and a main circuit unit providing power for the compressor. The devices include a compressor rotational speed obtaining unit, and a control unit that compares the rotational speed ω of the compressor with a rotational speed threshold ω1 of the compressor, and controls the main circuit unit according to comparison results. When the rotational speed ω is less than ω1, an output voltage of the main circuit unit is controlled at a fixed value. When the rotational speed ω is greater than or equal to ω1, the compressor is controlled not to enter the field weakening control temporarily and the output voltage of the main circuit unit is controlled to rise, the compressor is controlled to enter the field weakening control when the output voltage of the main circuit unit cannot continue to rise.