Abstract: The present invention relates to a method for controlling a bus current of a brushless DC electric motor, comprising: obtaining currents of three phases of a stator; converting the currents of the three phases to a direct-axis current and a quadrature-axis current; based on the direct-axis current, the quadrature-axis current and an efficiency ratio of the electric motor, determining a bus current of the electric motor, wherein the efficiency ratio corresponds to a present operating condition of the electric motor. The method does not need to introduce shunt resistors on the bus, and also enables closed-loop control of bus current.