Abstract: A method and for controlling a draught fan including: obtaining an actual rotating speed, an actual power, and a target air volume of the draught fan, obtaining a target power corresponding to the target air volume according to the actual rotating speed and the target air volume, obtaining, in response to a power difference value between the actual power and the target power being not within an initial difference value range, a control duration and a rotating speed step size corresponding to the power difference value, and adjusting the actual rotating speed according to the rotating speed step size after the control duration. A dynamic adjustment of the air volume of the draught fan is achieved, and a constant air volume control of the draught fan with low cost, high control accuracy, fast adjustment speed and good stability is achieved.

Abstract: A method for harmonic detection includes: acquiring a ripple component of a direct-current bus voltage; acquiring a harmonic component of the direct-current bus voltage based on the ripple component; acquiring a quadrature component of the harmonic component based on the harmonic component; acquiring a characteristic parameter of the harmonic component based on the quadrature component, in which the characteristic parameter includes a phase; and acquiring and outputting a voltage amplitude of the harmonic component based on the quadrature component and the phase of the harmonic component.

Abstract: The present invention provides an outdoor unit of air conditioner comprising a main body and an electrical component box, a fan motor, a compressor and a condenser which are all installed in the main body. The electrical component box comprises an electrical box cover, an electrical box, and a circuit board on which electrical components and a radiator are installed. The circuit board is disposed in the electrical box, the electrical box cover is installed on top of the electrical box, and a baffle box is disposed between the electrical box and the fan motor. In the outdoor unit of air conditioner of the present invention, the baffle box is disposed between the electrical box and the fan motor, and encloses the electrical box from the fan motor, which keeps the electrical box and the fan motor apart, prevents the fan motor from burning resulting from the fire source in the electrical box and further protects the outdoor unit of air conditioner from burning.