Motor drive device, controller, and electric vehicle system

A motor drive device, comprising:

• a power conversion circuit that drives an alternating-current motor;
• and
• a controller that controls the power conversion circuit, wherein
• the controller has
• a voltage command calculation unit that calculates a voltage command for operating the power conversion circuit on a basis of a current deviation, which is a difference between a current command and an actual current flowing through the alternating-current motor,
• a control state judgement unit that outputs a judgement signal corresponding to a control state of the power conversion circuit on a basis of the current deviation, and
• a control gain change unit that changes a control gain used for the voltage command calculation unit to calculate the voltage command on a basis of the judgement signal,
• the control state judgement unit outputs a first judgement signal when the current deviation satisfies a predetermined range condition and outputs a second judgement signal when the current deviation does not satisfy the range condition, and
• the control gain change unit
• immediately changes the control gain to a value corresponding to the second judgement signal when a judgement signal output from the control state judgement unit is switched from the first judgement signal to the second judgement signal, and
• changes, with a predetermined delay time, the control gain to a value corresponding to the first judgement signal when a judgement signal output from the control state judgement unit is switched from the second judgement signal to the first judgement signal.