Patent ID: 9461638
Filing Date: 2016-10-04
CPC Classification: H03K

Claim Text:
1. A drive unit for a switching element, comprising a charging unit which releases charge from an opening/closing control terminal of a voltage-control type switching element to switch a drive state of the switching element from an on-state to an off-state, wherein the switching element includes a sensing terminal which outputs a minute current having a correlation with current flowing between an input terminal and an output terminal of the switching element, the sensing terminal and either of the output terminal of the switching element or a member having a potential equal to that of the output terminal are connected via a sensing resistor, the charging unit includes a path which is connected to the switching element and which releases charge for switching the drive state of the switching element from an on-state to an off-state, and a first resistor and a second resistor which are provided on the path, the drive unit further comprises an active gate control unit which changes resistance of the path from low to high to change a discharge rate based on comparison of sensing voltage, which is a potential difference across the sensing resistor, or a rate of change of the sensing voltage with a specified value in a period from when releasing charge is started and until when it is completed; the charging unit of the drive unit further includes a charging switching element which switches the drive state of the switching element from an off state to an on state; and a first discharging switching element and a second discharging switching element which are connected to the first resistor and the second resistor, respectively, and switch the drive state of the switching element from an on state to an off state; the specified value is set based on individual-difference information of the switching element which indicates a characteristic, which affects the sensing voltage, when the drive state of the switching element is switched from an on state to an off state, the path of the charging unit has a first discharging path and a second discharging path which are connected to the opening/closing control terminal, the first and second discharging switching elements are provided on the first an second discharging paths, respectively, and are turned on and off to open and close the first and second discharging paths, respectively, the first and second resistors are provided on the first and second discharging paths, respectively, and in a period when releasing charge is started and until when it is completed, the active gate control unit changes resistance of the first and second resistors from low to high, in such a manner that the active gate control unit first turns on both of the first discharging switching element and the second discharging switching element to release the charge via both of the first and second resistors, and thereafter, the active gate control unit turns off the second discharging switching element to release the charge via the first resistor.