Zero-speed closed-loop starting method of direct-current variable-frequency air conditioner compressor

The invention discloses a zero-speed closed-loop starting method of a direct-current variable-frequency air conditioner compressor, relates to the technical field of compressor starting, and solves the problem that the motor position information cannot be accurately estimated under the zero-speed and ultra-low-speed conditions of the permanent magnet synchronous motor by most common position estimation methods and then the motor cannot directly start from the static state safely and reliably and operate at ultra-low speed. According to the technical scheme, the method is characterized by comprising the following steps: enabling an error current value to pass through a low-pass filter with proportional gain and variable bandwidth to obtain estimated electrical angular velocity; calculatingthe estimated electrical angular velocity to obtain an estimated position angle; calculating the estimated electrical angular velocity to obtain an estimated rotating speed; and estimating the rotating speed according to the