Short-circuit determining apparatus, switch apparatus and short-circuit determining method

1. A short-circuit determining apparatus comprising:

a sensor configured to detect a time change of a main current flowing between a first main terminal and a second main terminal of a switching device having a control terminal, the first main terminal and the second main terminal;

an integration unit configured to integrate an output of the sensor;

a polarity determining unit configured to determine a polarity of the output of the sensor; and

a short-circuit determining unit configured to determine a short-circuit of the switching device, based on a comparison result of an output of the integration unit and a short-circuit determination reference value according to a determination result of the polarity.

2. The short-circuit determining apparatus according to claim 1 , further comprising a reference output unit configured to output the short-circuit determination reference value to the short-circuit determining unit.

3. The short-circuit determining apparatus according to claim 2 , wherein

the reference output unit is configured to change the short-circuit determination reference value to be output, according to the determination result of the polarity.

4. The short-circuit determining apparatus according to claim 3 , wherein

the reference output unit is configured to initialize the short-circuit determination reference value to be output, in response to a control signal for driving the control terminal being turned off.

5. The short-circuit determining apparatus according to claim 2 , wherein

the integration unit includes a plurality of integrators each configured to integrate the output of the sensor, and

the reference output unit is configured to output a plurality of short-circuit determination reference values, each of which being identical to the short-circuit determination reference value, that are different from each other corresponding to each of the plurality of integrators,

the short-circuit determining apparatus further comprising a selection unit configured to select which of the plurality of integrators is to be used for integration of the output of the sensor, according to the determination result of the polarity.

6. The short-circuit determining apparatus according to claim 5 , wherein

the selection unit is configured to initialize a result of the selection, in response to a control signal for driving the control terminal being turned off.

7. The short-circuit determining apparatus according to claim 1 , further comprising a reset unit configured to reset the output of the integration unit when it is detected that the polarity of the output of the sensor has changed from positive to negative.

8. The short-circuit determining apparatus according to claim 2 , further comprising a reset unit configured to reset the output of the integration unit when it is detected that the polarity of the output of the sensor has changed from positive to negative.

9. The short-circuit determining apparatus according to claim 7 , wherein

when it is detected that the polarity of the output of the sensor has changed from positive to negative, the short-circuit determining unit is configured to determine a short-circuit of the switching device by using a second short-circuit determination reference value different from a first short-circuit determination reference value used before detection.

10. The short-circuit determining apparatus according to claim 9 , wherein

the second short-circuit determination reference value is smaller than the first short-circuit determination reference value.

11. The short-circuit determining apparatus according to claim 9 , wherein

in a case of determining the short-circuit of the switching device by using the second short-circuit determination reference value, when it is detected that the polarity of the output of the sensor has changed from positive to negative, the short-circuit determining unit is configured to determine the short-circuit of the switching device by using a third short-circuit determination reference value different from the first short-circuit determination reference value and the second short-circuit determination reference value.

12. The short-circuit determining apparatus according to claim 10 , wherein

in a case of determining the short-circuit of the switching device by using the second short-circuit determination reference value, when it is detected that the polarity of the output of the sensor has changed from positive to negative, the short-circuit determining unit is configured to determine the short-circuit of the switching device by using a third short-circuit determination reference value different from the first short-circuit determination reference value and the second short-circuit determination reference value.

13. The short-circuit determining apparatus according to claim 11 , wherein

the third short-circuit determination reference value is smaller than the second short-circuit determination reference value.

14. The short-circuit determining apparatus according to claim 11 , wherein

each time it is detected that the polarity of the output of the sensor has changed from positive to negative, the short-circuit determining unit is configured to determine the short-circuit of the switching device by using a new short-circuit determination reference value different from the short-circuit determination reference value used before detection.

15. The short-circuit determining apparatus according to claim 13 , wherein

each time it is detected that the polarity of the output of the sensor has changed from positive to negative, the short-circuit determining unit is configured to determine the short-circuit of the switching device by using a new short-circuit determination reference value different from the short-circuit determination reference value used before detection.

16. The short-circuit determining apparatus according to claim 1 , wherein

the short-circuit determining unit is configured to latch a short-circuit determination signal when the short-circuit of the switching device is detected.

17. The short-circuit determining apparatus according to claim 1 , wherein

the sensor is a Rogowskii coil.

18. The short-circuit determining apparatus according to claim 1 , wherein

the switching device is a wide bandgap semiconductor device whose main material is at least one of silicon carbide, gallium nitride, gallium oxide and diamond.

19. A switch apparatus comprising:

the switching device;

a control terminal drive unit configured to drive the control terminal of the switching device; and

the short-circuit determining apparatus according to claim 1 .

20. A short-circuit determining method comprising:

detecting, by a sensor, a time change of a main current flowing between a first main terminal and a second main terminal of a switching device having a control terminal, the first main terminal and the second main terminal;

integrating an output of the sensor;

determining a polarity of the output of the sensor; and

determining a short-circuit of the switching device, based on a comparison result of an integrated value of the output of the sensor and a short-circuit determination reference value according to a determination result of the polarity.