Method for discharging charges remaining in capacitor in apparatus

1. A drive apparatus for driving a rotating electric machine mounted on a vehicle by using electric power from a power storage device, said drive apparatus comprising:

a power conversion device including a switching element and converting the electric power from said power storage device;

a capacitor connected in parallel to said power conversion device; and

a control device for driving a control terminal of said switching element and discharging a charge stored in said capacitor, wherein

said power conversion device includes a plurality of reverse conducting-type semiconductor elements,

each of said plurality of reverse conducting-type semiconductor elements is integrally formed of a first semiconductor element operating as said switching element and a second semiconductor element connected in parallel to said first semiconductor element and operating as a free wheeling diode,

at the time of an operation for discharging said capacitor, said control device changes a voltage applied to said control terminal of said first semiconductor element and increases an electric power loss in said second semiconductor element during a current-circulating operation by said second semiconductor element, and

each of said plurality of reverse conducting-type semiconductor elements has a property that a conduction resistance of said second semiconductor element increases as the voltage applied to said control terminal of said first semiconductor element increases during said current-circulating operation.

2. The drive apparatus according to claim 1 , wherein

at the time of discharging said capacitor, said control device sets the voltage applied to said control terminal of said first semiconductor element included in the reverse conducting-type semiconductor element existing in a circulating path during said current-circulating operation, among said plurality of reverse conducting-type semiconductor elements, to be higher than a voltage applied when said rotating electric machine is driven.

3. The drive apparatus according to claim 1 , wherein

in each of said plurality of reverse conducting-type semiconductor elements, said first semiconductor element is formed of an IGBT and said second semiconductor element is formed of a diode connected in antiparallel to said IGBT.

4. The drive apparatus according to claim 1 , wherein

each of said plurality of reverse conducting-type semiconductor elements is formed of a power MOSFET, and

said second semiconductor element is a parasitic diode of said power MOSFET.

5. The drive apparatus according to claim 1 , wherein

said vehicle includes a crash detecting unit for detecting a crash of said vehicle, and

when said crash detecting unit detects the crash of said vehicle, said control device drives said control terminal of said switching element and discharges the charge stored in said capacitor.

6. The drive apparatus according to claim 2 , wherein

said power conversion device is an inverter including at least one of said plurality of reverse conducting-type semiconductor elements and driving said rotating electric machine, and

at the time of discharging said capacitor, said control device discharges the charge in said capacitor by using said inverter and said rotating electric machine.

7. The drive apparatus according to claim 2 , wherein

said power conversion device is a converter including at least one of said plurality of reverse conducting-type semiconductor elements and a reactor, which constitute a chopper circuit, and converting a DC voltage supplied from said power storage device, and

at the time of discharging said capacitor, said control device controls said converter to discharge the charge in said capacitor using said reactor.

8. The drive apparatus according to claim 6 , wherein

said control device discharges the charge in said capacitor by causing a coil included in said rotating electric machine to consume the charge, without rotating said rotating electric machine.

9. A drive apparatus for driving a rotating electric machine mounted on a vehicle by using electric power from a power storage device, said drive apparatus comprising:

an inverter having at least one reverse conducting-type semiconductor element integrally formed of a first semiconductor element operating as a switching element and a second semiconductor element connected in parallel to said first semiconductor element and operating as a free wheeling diode, and driving said rotating electric machine;

a capacitor connected in parallel to said inverter; and

a control device for driving a control terminal of said switching element and discharging a charge stored in said capacitor, wherein

at the time of an operation for discharging said capacitor, said control device changes a voltage applied to said control terminal of said first semiconductor element and increases an electric power loss in said second semiconductor element during a current-circulating operation by said second semiconductor element, and

each of said plurality of reverse conducting-type semiconductor elements has a property that a conduction resistance of said second semiconductor element increases as the voltage applied to said control terminal of said first semiconductor element increases during said current-circulating operation.

10. The drive apparatus according to claim 9 , further comprising

a converter having said reverse conducting-type semiconductor element, and converting a DC voltage from said power storage device and supplying converted said DC voltage to said inverter.

11. A vehicle, comprising:

a power storage device;

a rotating electric machine; and

a drive apparatus for driving said rotating electric machine by using electric power from said power storage device, and generating running drive force,

said drive apparatus including:

a power conversion device having a switching element and converting the electric power from said power storage device;

a capacitor connected in parallel to said power conversion device; and

a control device for driving a control terminal of said switching element and discharging a charge stored in said capacitor, wherein

said power conversion device includes a plurality of reverse conducting-type semiconductor elements,

each of said plurality of reverse conducting-type semiconductor elements is integrally formed of a first semiconductor element operating as said switching element and a second semiconductor element connected in parallel to said first semiconductor element and operating as a free wheeling diode,

at the time of an operation for discharging said capacitor, said control device changes a voltage applied to said control terminal of said first semiconductor element and increases an electric power loss in said second semiconductor element during a current-circulating operation by said second semiconductor element, and

each of said plurality of reverse conducting-type semiconductor elements has a property that a conduction resistance of said second semiconductor element increases as the voltage applied to said control terminal of said first semiconductor element increases during said current-circulating operation.

12. A method for controlling a drive apparatus for driving a rotating electric machine mounted on a vehicle by using electric power from a power storage device,

said drive apparatus including:

a power conversion device having a switching element and converting the electric power from said power storage device; and

a capacitor connected in parallel to said power conversion device,

said power conversion device including a plurality of reverse conducting-type semiconductor elements,

each of said plurality of reverse conducting-type semiconductor elements being integrally formed of a first semiconductor element operating as said switching element and a second semiconductor element connected in parallel to said first semiconductor element and operating as a free wheeling diode,

said method comprising the steps of:

driving a control terminal of said switching element and discharging a charge stored in said capacitor; and

at the time of discharging the charge in said capacitor, changing a voltage applied to said control terminal of said first semiconductor element and increasing an electric power loss in said second semiconductor element during a current-circulating operation by said second semiconductor element, wherein

each of said plurality of reverse conducting-type semiconductor elements has a property that a conduction resistance of said second semiconductor element increases as the voltage applied to said control terminal of said first semiconductor element increases during said current-circulating operation.