Motor inductance measuring device, motor drive system, and motor inductance measuring method

A motor inductance measurement device (50) measures inductance information (InfL) including characteristics (56a, 56b) of an instantaneous value of an AC magnetic flux ([phi] qsAC) corresponding to an instantaneous value of an AC current (iqsAC) flowing through a motor (1). A measurement device (50) is provided with: an energization control unit (2) that performs energization control such that an alternating current (iqsAC) flows by applying an alternating current voltage (vqAC) to at least one axis on two-axis orthogonal rotational coordinates of a motor (1); and an inductance calculation unit (3) that calculates an instantaneous value of the AC magnetic flux ([phi] qsAC) by integrating a residual voltage obtained by subtracting, from the AC voltage (vqAC), an AC current (iqsAC) obtained from a detection current (94) detected from the motor (1) and a resistance voltage generated from resistors (Rs, Rr) of the motor (1). Characteristics (56a, 56b) of the instantaneous value of the AC magnetic flux ([phi] qsAC