Fault-tolerant operation of hybrid electric vehicle
First Claim
1. A hybrid drive system comprising:
- a DC power source;
an internal combustion engine;
a traction motor;
a generator;
a variable voltage converter (VVC) selectably coupled to the power source;
a motor inverter;
a generator inverter;
a bus coupling an output of the VVC to the inverters; and
a controller regulating an engine speed, a motor torque, and a generator torque;
wherein the controller detects a fault in which the power source and VVC are unavailable for regulating a bus voltage on the bus; and
wherein upon detecting the fault, the controller regulates a motor inverter power output to match a sum of a generator inverter power output and an estimated power loss of the inverters.
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Accused Products
Abstract
A hybrid drive system has a battery and a combustion engine for energy sources. The system has a traction motor, a generator, a variable voltage converter (VVC), a motor inverter, a generator inverter, a bus coupling the VVC to the inverters, and a controller. The controller regulates engine speed, motor torque, and generator torque. The engine speed is determined according to a driver torque demand. In normal conditions, 1) the controller regulates the engine speed by modifying a generator torque command, and 2) the bus voltage is regulated using the VVC and battery. When the controller detects a fault in which the battery and VVC become unavailable for regulating the bus voltage, then the controller regulates a motor inverter power output to match a sum of a generator inverter power output and an estimated power loss of the inverters in order to regulate the bus voltage.
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Citations
12 Claims
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1. A hybrid drive system comprising:
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a DC power source; an internal combustion engine; a traction motor; a generator; a variable voltage converter (VVC) selectably coupled to the power source; a motor inverter; a generator inverter; a bus coupling an output of the VVC to the inverters; and a controller regulating an engine speed, a motor torque, and a generator torque; wherein the controller detects a fault in which the power source and VVC are unavailable for regulating a bus voltage on the bus; and wherein upon detecting the fault, the controller regulates a motor inverter power output to match a sum of a generator inverter power output and an estimated power loss of the inverters. - View Dependent Claims (2, 3)
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4. A hybrid drive system comprising:
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a DC power source; an internal combustion engine; a traction motor; a generator; a variable voltage converter (VVC) selectably coupled to the power source; a motor inverter; a generator inverter; a bus coupling an output of the VVC to the inverters; and a controller regulating an engine speed, a motor torque, and a generator torque; wherein the controller detects a fault in which the power source and VVC are unavailable for regulating a bus voltage on the bus; and wherein upon detecting the fault, the controller generates a motor torque command according to A) an error between the bus voltage and a predetermined voltage, and B) a generator inverter power output. - View Dependent Claims (5, 6)
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7. A DC balancing control in a hybrid vehicle having a motor inverter and a generator inverter, comprising:
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a voltage regulator providing a control signal according to a difference between a voltage at an inverter bus and a reference voltage when the bus is isolated from a vehicle battery; and a combiner generating a motor inverter power target according to a difference between the control signal and a power output from the generator inverter. - View Dependent Claims (8, 9)
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10. A method of controlling a hybrid drive system having a battery, an internal combustion engine, a traction motor, a generator, a variable voltage converter (VVC) selectably coupled to the battery, a motor inverter, a generator inverter, a bus coupling an output of the VVC to the inverters, and a controller, the method comprising the steps of:
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detecting whether the battery and VVC are available for regulating a voltage on the bus; when the battery and VVC are available, then performing the steps of; determining an engine speed command according to a driver torque command, an actual vehicle speed, and a battery state of charge; regulating engine speed to the engine speed command by modifying a generator torque command for the generator inverter; and determining a motor torque command for the motor inverter according to the driver torque command and the generator torque command; and when the battery and VVC are not available, then performing the steps of; determining an engine speed command according to the driver torque command and the actual vehicle speed, without regard to the battery state of charge; regulating engine speed to the engine speed command by modifying a generator torque command for the generator inverter; and regulating the motor torque command to obtain a motor power output that matches a power loss of the inverters plus a generator power output that results from the modified generator torque command. - View Dependent Claims (11, 12)
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Specification