Power conversion apparatus
A power conversion apparatus accurately estimates a main current of a power device using observation of a sense current. The power conversion apparatus includes: an inverter circuit including a device having a main element and a sense element; a temporary-main-current estimator estimates a current flowing through the main element, from a sense current flowing through the sense element, as a temporary main current; a temperature-difference estimator configured to estimate a temperature difference between the main element and the sense element based on a gate drive signal for the main element and the temporary main current; a main-current corrector corrects the temporary main current using the estimated temperature difference and a temperature characteristic of on-resistance of the main element and output the corrected temporary main current as a corrected main current; and an inverter control circuit configured to output the gate drive signal based on the corrected main current.
1. A power conversion apparatus comprising:
an inverter circuit including a device having a main element and a sense element;
a temporary-main-current estimator configured to estimate a main current flowing through the main element, from a sense current flowing through the sense element, as a temporary main current;
a temperature-difference estimator configured to output an estimated temperature difference between the main element and the sense element based on a gate drive signal for the main element and the temporary main current;
a main-current corrector configured to correct the temporary main current using the estimated temperature difference and a temperature characteristic of on-resistance of the main element and output a corrected temporary main current as a corrected main current; and
an inverter control circuit configured to output the gate drive signal based on the corrected main current,
wherein the temporary-main-current estimator estimates the temporary main current based on a sense ratio that is a pre-acquired ratio between the main current and the sense current, and
wherein the temperature-difference estimator includes a chip-loss calculator that calculates an estimated loss based on the temporary main current, and a temperature-difference calculator that calculates the estimated temperature difference based on the estimated loss.
2. The power conversion apparatus according to claim 1 , wherein
the device includes a temperature sensitive element, and
the temporary-main-current estimator corrects a temperature of the temporary main current based on a sense-element temperature detected from an output of the temperature sensitive element.
3. The power conversion apparatus according to claim 1 , wherein
the main-current corrector includes a correction-coefficient calculator that calculates a correction coefficient based on the estimated temperature difference.
4. The power conversion apparatus according to claim 3 , wherein
the main-current corrector multiplies the temporary main current by the correction coefficient to obtain the corrected main current.
5. The power conversion apparatus according to claim 4 , wherein
the main-current corrector multiplies a temperature coefficient of the on-resistance of the main element and the estimated temperature difference at a temperature of the sense element, to obtain the correction coefficient.
6. The power conversion apparatus according to claim 1 , wherein
the temperature-difference estimator estimates a temperature difference between the main element and the sense element based on an intended driving condition for the device.
7. The power conversion apparatus according to claim 6 , wherein
the intended driving condition includes an intended main current value in next switching and a pulse width of the intended main current value.
8. The power conversion apparatus according to claim 1 , further comprising:
a second temperature-difference estimator configured to estimate a temperature difference from the corrected main current; and
a second main-current corrector configured to calculate a second correction coefficient based on a second estimated temperature difference estimated by the second temperature-difference estimator and multiply the corrected main current by the second correction coefficient.
9. A power conversion apparatus comprising:
an inverter circuit including a device having a main element and a sense element;
a temporary-main-current estimator configured to estimate a main current flowing through the main element, from a sense current flowing through the sense element, as a temporary main current;
a temperature-difference estimator configured to output an estimated temperature difference between the main element and the sense element based on a gate drive signal for the main element and the temporary main current;
a main-current corrector configured to correct the temporary main current using the estimated temperature difference and a temperature characteristic of on-resistance of the main element and output a corrected temporary main current as a corrected main current;
an inverter control circuit configured to output the gate drive signal based on the corrected main current,
a second temperature-difference estimator configured to estimate a temperature difference from the corrected main current; and
a second main-current corrector configured to calculate a second correction coefficient based on a second estimated temperature difference estimated by the second temperature-difference estimator and multiply the corrected main current by the second correction coefficient.
10. The power conversion apparatus according to claim 9 , wherein
the temporary-main-current estimator estimates the temporary main current based on a sense ratio that is a pre-acquired ratio between the main current and the sense current.
11. The power conversion apparatus according to claim 10 , wherein
the device includes a temperature sensitive element, and
the temporary-main-current estimator corrects a temperature of the temporary main current based on a sense-element temperature detected from an output of the temperature sensitive element.
12. The power conversion apparatus according to claim 10 , wherein
the temperature-difference estimator includes a chip-loss calculator that calculates an estimated loss based on the temporary main current, and a temperature-difference calculator that calculates the estimated temperature difference based on the estimated loss.
13. The power conversion apparatus according to claim 12 , wherein
the main-current corrector includes a correction-coefficient calculator that calculates a correction coefficient based on the estimated temperature difference.
14. The power conversion apparatus according to claim 13 , wherein
the main-current corrector multiplies the temporary main current by the correction coefficient to obtain the corrected main current.
15. The power conversion apparatus according to claim 14 , wherein
the main-current corrector multiplies a temperature coefficient of the on-resistance of the main element and the estimated temperature difference at a temperature of the sense element, to obtain the correction coefficient.
16. The power conversion apparatus according to claim 9 , wherein
the temperature-difference estimator estimates a temperature difference between the main element and the sense element based on an intended driving condition for the device.
17. The power conversion apparatus according to claim 16 , wherein
the intended driving condition includes an intended main current value in next switching and a pulse width of the intended main current value.