The invention discloses a diagnosis method for an open-circuit fault of an
inverter power tube. The diagnosis method comprises the following steps: S1, acquiring a measured value of linear
voltage between any two bridge arms of an
inverter, taking the measured value as a measured
voltage Vijm, estimating the linear
voltage between the any two bridge arms according to a preset linear voltage
estimation model, taking the linear voltage as an estimated voltage Vije, and performing one-to-one correspondence between the measured voltage Vijm and the estimated voltage Vije, wherein the i and the j represent orders of the two bridge arms respectively, i belongs to {0, 1}, j belongs to {0, 1}, and i is not equal to the j; S2, calculating an error voltage deltaij between the corresponding measured voltage Vijm and the estimated voltage Vije, and judging whether a power tube on one bridge arm generates the open-circuit fault according to an amplitude of the error voltage
delta ij and a pulse width; S3, when the power tube generates the open-circuit fault, positioning a fault bridge arm and a fault power tube according to positive polarity and negative polarity of the error voltage
delta ij. The invention provides the diagnosis method for the open-circuit fault of the
inverter power tube, which can effectively improve the fault diagnosis for safety and reliability of the inverter.