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US 12,738,877 B2Granted
Method and system for controlling an electric machine
AssigneeGM Global Technology Operations LLC
InventorsTanvi Nagarale, Brent S. Gagas, Brian A. Welchko
Life of this patent
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Abstract
A control system for a rotary electric machine includes an inverter including a plurality of power switches, a heat exchanger, first temperature sensors arranged to monitor the power switches, a second temperature sensor arranged to monitor the heat exchanger, and a controller. An expected power loss is determined based upon electric current, switching functions, and electrical characteristics of the power switches. A plurality of power capacity terms are determined based upon the expected power loss in the inverter, the temperatures of the power switches, and the temperature of the heat exchanger. The inverter is controlled based upon the aforementioned power capacities.
Claims18
A control system for a multi-phase electric machine (electric machine), comprising:
- an inverter configured to transfer electric energy from a rechargeable energy storage device (RESS) to the electric machine, wherein the inverter is composed of a plurality of power switches;
- a plurality of first temperature sensors, wherein the plurality of first temperature sensors are arranged to monitor a plurality of semiconductor junction temperatures of the plurality of power switches;
- a heat exchanger, the heat exchanger thermally coupled to the inverter;
- a second temperature sensor, wherein the second temperature sensor is arranged to monitor a parameter of the heat exchanger;
- a position sensor arranged to monitor rotation of the electric machine;
- and
- a controller, the controller being operatively connected to the inverter and in communication with the plurality of first temperature sensors, the second temperature sensor, and the position sensor, the controller including an instruction set, the instruction set being executable to:
- determine, via the plurality of first temperature sensors, the plurality of semiconductor junction temperatures of the plurality of power switches;
- determine, via the second temperature sensor, the parameter of the heat exchanger;
- determine, via the position sensor, a rotational position of the electric machine;
- and
- control an electric power output from the inverter to the electric machine based upon the plurality of semiconductor junction temperatures of the plurality of power switches, the rotational position of the electric machine, and the parameter of the heat exchanger;
- and
- wherein the controller is operative to:
- determine an expected power loss in the inverter based upon the plurality of semiconductor junction temperatures of the plurality of power switches, and determine a first temperature parameter based upon the expected power loss in the inverter and the parameter of the heat exchanger;
- determine a first power capacity based upon the expected power loss in the inverter and the first temperature parameter;
- determine a second temperature parameter based upon the plurality of semiconductor junction temperatures of the plurality of power switches, and determine a second power capacity based upon the second temperature parameter;
- determine a third temperature parameter based upon the first temperature parameter and a difference between the plurality of semiconductor junction temperatures of the plurality of power switches and the parameter of the heat exchanger, and determine a third power capacity based upon the third temperature parameter;
- determine a fourth temperature parameter based upon a difference between the temperatures of the plurality of power switches and the parameter of the heat exchanger, and determine a fourth power capacity based upon the fourth temperature parameter;
- and
- control electric power output from the inverter to the electric machine based upon the first power capacity, the second power capacity, the third power capacity, and the fourth power capacity and the rotational position of the electric machine.
18 more elements
A derating method for an electric machine, comprising:
- determining a first derating of the electric machine based on a model-based semiconductor junction temperature estimation;
- determining a second derating of the electric machine based on a sensor-based semiconductor junction temperature estimation;
- determining a third derating of the electric machine based on difference between the model-based semiconductor junction temperature estimation and a coolant temperature;
- determining a fourth derating of the electric machine based upon a difference between the sensor-based semiconductor junction temperature estimation and the coolant temperature;
- and
- derating power output from the electric machine based upon a minimum of the first derating, the second derating, the third derating, and the fourth derating;
- wherein determining the second derating based on the sensor-based semiconductor junction temperature estimation comprises:
- estimating semiconductor junction temperature directly from a sensor measurement;
- estimating semiconductor junction temperature from the sensor measurement and a coolant temperature;
- calculating the second derating and the third derating based upon sensor-mapped semiconductor junction temperatures and pre-determined thresholds using linear interpolation;
- and
- calculating a final derating based upon one of an average or a maximum of the second derating or the third derating.
9 more elements
Dependencies are inferred from the claim text.