Method and system for discharging a capacitive element in an electrically operable vehicle
First Claim
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1. A method to discharge a capacitor in an automotive electric drive system of an electric vehicle, wherein the electric drive system includes a DC electric power source coupled by contactors to the capacitor for providing power to an electric motor coupled to a pair of wheels to drive the vehicle, the method comprising:
- determining a disconnect of the contactors;
discharging the capacitor in response to the disconnect by controllably transferring energy from the capacitor to the electric motor without driving the wheels;
wherein the electric drive system includes an electric motor controller coupled between the capacitor and the electric motor to controllably transfer energy from the capacitor to the electric motor by controlling current drawn from the capacitor and voltage provided to the electric motor; and
wherein discharging the capacitor comprises controlling flux and torque produced by the electric motor to produce positive power flow from the capacitor to the electric motor.
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Abstract
An electric drive system having a power source which provides power to an electric motor through an electric motor control. Discharging of stored capacitor energy of a capacitor coupled between the power source and the electric motor controller is provided by controlling energy transfer from the capacitor to the electric motor.
21 Citations
20 Claims
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1. A method to discharge a capacitor in an automotive electric drive system of an electric vehicle, wherein the electric drive system includes a DC electric power source coupled by contactors to the capacitor for providing power to an electric motor coupled to a pair of wheels to drive the vehicle, the method comprising:
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determining a disconnect of the contactors; discharging the capacitor in response to the disconnect by controllably transferring energy from the capacitor to the electric motor without driving the wheels; wherein the electric drive system includes an electric motor controller coupled between the capacitor and the electric motor to controllably transfer energy from the capacitor to the electric motor by controlling current drawn from the capacitor and voltage provided to the electric motor; and wherein discharging the capacitor comprises controlling flux and torque produced by the electric motor to produce positive power flow from the capacitor to the electric motor. - View Dependent Claims (2, 3, 4, 5, 6, 17)
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7. An automotive electric distribution system for use in an electric vehicle, the system comprising:
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a DC power source to provide DC energy; a capacitor coupled to the power source; a pair of contactors connected between the DC power source and the capacitor to electrically separate the DC power source from the capacitor if the contactors are open; an AC electric motor coupled to the power source and coupled to a pair of wheels to drive the vehicle; an electric motor controller coupled between the capacitor and the electric motor to control voltage provided to the electric motor; a software program to discharge the capacitor by controlling the electric motor controller such that energy can be controllably transferred from the capacitor to the electric motor without increasing power used to drive the vehicle by controlling current drawn from the capacitor and voltage provided to the electric motor; and wherein the software program controls discharging of the capacitor by controlling flux and torque produced by the electric motor. - View Dependent Claims (8, 9, 10, 11)
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12. A method to discharge a capacitor in an electric vehicle electric drive system, wherein the electric drive system includes a DC electric power source coupled by contactors to the capacitor for providing power to an electric motor, the method comprising:
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determining a disconnect of the contactors; and controllably discharging the capacitor in response to the disconnect by controlling flux and torque produced by the electric motor such that stored capacitor energy is controllably transferred from the capacitor to the electric motor. - View Dependent Claims (13, 14)
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15. A method for discharging a capacitive element coupled across a power source of an electric drive system, the method comprising:
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charging the capacitive element with current drawn from the power source; controllably discharging the capacitive element by controlling current drawn from the capacitive element and transferred to an electric motor without causing the electric motor to drive a device connected thereto; and wherein discharging the capacitive element comprises controlling flux and torque produced by the electric motor to produce positive power flow from the capacitive element to the electric motor. - View Dependent Claims (16)
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18. A method to discharge a capacitor in an automotive electric drive system of an electric vehicle, wherein the electric drive system includes a DC electric power source coupled by contactors to the capacitor for providing power to an electric motor coupled to a pair of wheels to drive the vehicle, the method comprising:
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determining a disconnect of the contactors; discharging the capacitor in response to the disconnect by controllably transferring energy from the capacitor to the electric motor without driving the wheels; wherein discharging the capacitor includes controlling the electric motor to consume energy from the capacitor; and wherein the electric motor is controlled to consume energy without producing torque.
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19. A method to discharge a capacitor in an automotive electric drive system of an electric vehicle, wherein the electric drive system includes a DC electric power source coupled by contactors to the capacitor for providing power to an electric motor coupled to a pair of wheels to drive the vehicle, the method comprising:
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determining a disconnect of the contactors; discharging the capacitor in response to the disconnect by controllably transferring energy from the capacitor to the electric motor without driving the wheels; wherein discharging the capacitor includes controlling the electric motor to consume energy from the capacitor; and further comprising determining an amount of torque required to drive the vehicle with the electric motor, wherein the electric motor is controlled to consume energy by providing torque less than the amount of torque required to drive the vehicle. - View Dependent Claims (20)
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Specification