Initial speed detecting method for outdoor fan of DC (direct current) inverter air conditioner

The invention relates to an initial speed detecting method for an outdoor fan of a DC inverter air conditioner. The outdoor fan of the DC inverter air conditioner adopts a FOC control algorithm, comprising the following steps of: S1, setting a cross-axis target current IqReg and a direct-axis target current IdReg equal to 0, and operating a speed loop in an open-loop mode and a current loop in a closed-loop mode; S2, detecting and obtaining a voltage value V[alpha] output by a fan [alpha]-axis and a voltage value V[beta] output by a fan [beta]-axis; S3, passing the V[alpha] and V[beta] througha phase-locked loop module, and outputting an electrical angular velocity [omega] of a signal; S4, converting the electric angular velocity [omega] to obtain an initial speed Speed 0 of the fan. Themethod can effectively detect the initial speed of the fan through a software program without adding any hardware cost according to an application situation of a sensorless position of the outdoor fanof a DC inverter air condi