Control device for an AC rotating electric machine

1. A control device for an AC rotating electric machine, the control device comprising:

a temperature detection unit configured to detect a temperature of a protection unit provided in an object to be protected when a current is supplied from a power conversion circuit including a switching element to the AC rotating electric machine and output, as a detected temperature, one of the temperature and a temperature of the object to be protected that is estimated from the temperature;

a temperature compensation unit configured to calculate, through use of the detected temperature, a compensated temperature equal to or higher than the detected temperature; and

a torque limiting unit configured to limit, through use of the compensated temperature calculated by the temperature compensation unit, a torque command value input thereto,

wherein the torque limiting unit includes:

an arithmetic unit configured to calculate a difference between the compensated temperature calculated by the temperature compensation unit and a set temperature set in advance;

a maximum current adjustment unit configured to adjust, through use of the difference, a maximum quantity of the current supplied from the power conversion circuit to the AC rotating electric machine so as to prevent the compensated temperature from exceeding the set temperature;

an allowable torque calculation unit configured to calculate an upper limit value and a lower limit value of the torque command value based on the maximum current quantity adjusted by the maximum current adjustment unit; and

a torque command adjustment unit configured to adjust the torque command value based on each of the upper limit value and the lower limit value.

2. A control device for an AC rotating electric machine, the control device comprising:

a temperature detection unit configured to detect a temperature of a protection unit provided in an object to be protected when a current is supplied from a power conversion circuit including a switching element to the AC rotating electric machine and output, as a detected temperature, one of the temperature and a temperature of the object to be protected that is estimated from the temperature;

a temperature compensation unit configured to calculate, through use of the detected temperature, a compensated temperature equal to or higher than the detected temperature; and

a torque limiting unit configured to limit, through use of the compensated temperature calculated by the temperature compensation unit, a torque command value input thereto,

wherein the temperature compensation unit includes:

a compensation amount calculation unit configured to calculate a compensation amount through use of the detected temperature; and

an addition unit configured to add the compensation amount to the detected temperature to calculate the compensated temperature.

3. The control device for the AC rotating electric machine according to claim 2 ,

wherein the temperature compensation unit further includes:

a compensation amount limiting unit configured to limit a range of the compensation amount, and

wherein the addition unit is configured to add, to the detected temperature, the compensation amount limited by the compensation amount limiting unit to calculate the compensated temperature.

4. The control device for the AC rotating electric machine according to claim 2 , wherein the compensation amount calculation unit has respective functions of an amplifier, a low-pass filter, and a high-pass filter, and is configured to perform, on the temperature detected by the temperature detection unit, an operation using an amplification factor, a transmission function of the low-pass filter, and a transmission function of the high-pass filter to calculate the compensation amount.

5. The control device for the AC rotating electric machine according to claim 1 , further comprising:

a voltage detection unit configured to detect a DC voltage value of a DC power source; and

an electric angular speed detection unit configured to detect an electric angular speed of the AC rotating electric machine,

wherein the allowable torque calculation unit is configured to:

calculate, based on the DC voltage value detected by the voltage detection unit and on a maximum modulation factor set in advance, a maximum value of a voltage to be applied to the AC rotating electric machine;

calculate, based on the maximum voltage value and on the electric angular speed, a maximum interlinkage magnetic flux of the AC rotating electric machine; and

calculate, based on the maximum interlinkage magnetic flux and on the adjusted maximum current quantity, the upper limit value and the lower limit value.

6. The control device for the AC rotating electric machine according to claim 1 , wherein the torque command adjustment unit is configured to adjust the torque command value by:

setting, when the torque command value is larger than the upper limit value, the torque command value to the upper limit value,

setting, when the torque command value is smaller than the lower limit value, the torque command value to the lower limit value, and

maintaining, when the torque command value is in a range equal to or higher than the lower limit value and equal to or lower than the upper limit value, the same torque command value without controlling the torque command value.

7. The control device for the AC rotating electric machine according to claim 1 ,

wherein the temperature compensation unit comprises, when the protection unit comprises a plurality of protection units provided in a plurality of different objects to be protected, a plurality of temperature compensation units provided individually for the plurality of protection units,

wherein the arithmetic unit comprises a plurality of arithmetic units;

wherein the torque limiting unit includes the plurality of arithmetic units provided individually for the plurality of temperature compensation units, and

wherein the maximum current adjustment unit included in the torque limiting unit is configured to adjust the maximum quantity of the current supplied from the power conversion circuit to the AC rotating electric machine through use of a minimum one of differences individually calculated by the plurality of arithmetic units.