Current sensor abnormality diagnosis device

A current sensor abnormality diagnosis device capable of detecting occurrence of abnormality of each of plural phase current sensors and a bus current sensor, the plural phase current sensors detecting three phase currents which flow in three phases of a three phase alternating current motor, the bus current sensor detecting a bus current which flows in a bus line, one terminal of the bus line being connected to a direct current power source or being earthed,

• the current sensor abnormality diagnosis device comprising a computer system including a central processing unit, the computer system being configured to provide:
• a current comparison section which compares a three phase current sum with a predetermined three phase current threshold value and compares each of the three phase currents with the bus current, where the three phase current sum being a sum of the three phase currents;
• and
• an abnormality judgment section which executes abnormality diagnosis of the phase current sensors or the bus current sensor, and the abnormality judgment section detecting that one of the phase current sensors has failed when the three phase current sum is not more than the predetermined three phase current threshold value, the abnormality judgment section determining whether the bus current sensor is operating normally on the basis of the comparison result of the three phase currents and the bus current, and the abnormality judgment section determining that one of the phase current sensors has failed on the basis of the comparison result between the three phase currents and the bus current when the three phase current sum is more than the predetermined three phase current threshold value.