Gate driving apparatus, switching apparatus and gate driving method

A gate driving apparatus comprising:

• a gate driving unit for driving a gate of a switching device;
• a switching unit for switching a gate current of the switching device during, within a turn-on period of the switching device, at least a part of a period, which starts after timing when a current starts to flow in the switching device, to a smaller current when compared to the gate current before the at least a part of the period;
• and
• a first detection unit for detecting elapse of a first reference period, which is from first reference timing after a turn-on signal is input into the switching device to after the timing when the current starts to flow in the switching device, and for supplying a signal to the switching unit, wherein
• the first reference timing is after an input timing of a turn-on signal to the switching device;
• the switching device is connected in series with an opposite switching device that is connected in antiparallel to a freewheeling diode;
• and
• the gate driving apparatus further comprises:
• a first acquisition unit for acquiring at least one of a parameter indicating a gate voltage of the switching device, a parameter showing a device voltage of the switching device, a parameter showing a current flowing in the switching device, and a parameter showing a current flowing in the freewheeling diode;
• and
• a second detection unit for detecting the first reference timing, and supplying a signal to the first detection unit based on a parameter acquired by the first acquisition unit.

A gate driving apparatus comprising:

• a gate driving unit for driving a gate of a switching device;
• a switching unit for switching a gate current of the switching device during, within a turn-on period of the switching device, at least a part of a period, which starts after timing when a current starts to flow in the switching device, to a smaller current when compared to the gate current before the at least a part of the period;
• the switching device is connected in series with an opposite switching device that has a freewheeling diode connected thereto in antiparallel;
• the at least a part of the period includes timing when a current flowing in the freewheeling diode becomes zero;
• a second acquisition unit for acquiring at least one of a parameter showing a current flowing in the freewheeling diode and a parameter showing a current flowing in the switching device;
• and
• a third detection unit for detecting that a current flowing in the freewheeling diode has become zero and supplying a signal to the switching unit based on a parameter acquired by the second acquisition unit.

A gate driving apparatus comprising:

• a gate driving unit for driving a gate of a switching device, the switching device being connected in series with an opposite switching device that has a freewheeling diode connected thereto in antiparallel;
• a switching unit for switching a gate current of the switching device during, within a turn-on period of the switching device, at least a part of a period, which is after timing when a current starts to flow in the switching device, to a smaller current when compared to the gate current before the at least a part of the period;
• and
• a fourth detection unit for detecting elapse of a second reference period, which is from a second reference timing after a turn-on signal is input into the switching device to that after a timing when a current flowing in the freewheeling diode becomes zero, and supplying a signal to the switching unit, wherein
• the at least a part of the period includes the timing when the current flowing in the freewheeling diode becomes zero.

A gate driving method for driving a gate of a switching device, comprising:

• switching a slope of a gate current of the switching device, within a turn-on period of the switching device, from a first constant slope during at least a first part of the turn-on period to a second constant slope more negative than the first constant slope during at least a second part of the turn-on period after the first part of the turn-on period;
• and
• an input to the switching unit, the input having two levels in operation:
• an ON level and an OFF level, wherein
• the first part of the turn-on period is after a device current starts to flow in the switching device, and
• a turn-on signal is continuously input to the switching device during the turn-on period, the turn-on period being a single cycle of the input to the switching unit at an ON level.