Engine load management for traction vehicles

• US 8,140,206 B2
• Filed: 09/15/2008
• Issued: 03/20/2012
• Est. Priority Date: 09/15/2008
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Bailey, Bradley, Hendrickson, Matthew, Tate, William J., Earleson, Walter E., Brand, Jeffrey A.
• Primary Examiner(s): Fleming, Faye M.
• Application Number:
  US12/210,861
• Publication Number:
  US 20100070120A1
• Time in Patent Office: 1,282 Days
• Field of Search: 701/22, 318/473, 280/65.1, 280/65.3
• US Class Current: 701/22
• CPC Class Codes: B60K 6/46 Series type
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2240/662 Temperature
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 2510/0623 Fuel flow rate
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2510/081 Speed
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2555/20 Ambient conditions, e.g. wind or rain
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 30/184 Preventing damage resulting from overload or excessive wear of the driveline
• CPC Class Codes: B60W 30/1884 Avoiding stall or overspeed of the engine
• CPC Class Codes: B60W 50/0097 Predicting future conditions
• CPC Class Codes: B60Y 2200/14 Trucks; Load vehicles, Busses
• CPC Class Codes: B60Y 2200/142 Heavy duty trucks
• CPC Class Codes: H02P 29/032 : Preventing damage to the motor, e.g. setting individual current limits for different drive conditions
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y02T 90/16 : Information or communication technologies improving the operation of electric vehicles

Abstract

An electric drive system includes a fuel-driven engine (202) driving an electrical power generator (204) that provides power to one or more electric drive motors (210). A method of load management in the electric drive system includes receiving an actual fuel signal, an engine speed (920) signal, a throttle position signal, a motor speed (712) signal, an intake air pressure, a barometric pressure signal, and an intake air temperature signal. These values are used to determine a torque limit. The torque limit is used to limit a torque command to the electric drive motors (210) such that the torque command is consistent with the operating capabilities of the engine (202).

Claims

1. A method of load management within an electric drive system, the electric drive system including an engine having an output for driving an electrical power generator, the electrical power generator providing power to one or more electric drive motors, the method comprising:

receiving an actual fuel signal indicative of an amount of fuel commanded to the engine;

receiving an engine speed signal indicative of a rotational speed of the output for driving the electrical power generator;

receiving a throttle position signal indicative of an acceleration or deceleration commanded by an operator of a machine;

receiving a motor speed signal indicative of a rotating speed of the one or more electric drive motors;

receiving a barometric pressure signal indicative of an altitude of operation of the machine;

receiving an intake air temperature signal indicative of an ambient temperature;

receiving an intake air pressure signal indicative of a pressure of air within an intake manifold of the engine;

determining a torque limit to limit a torque command to the one or more electric drive motors based on the received signals such that the torque command is consistent with the operating capabilities of the engine.

2. The method of load management within an electric drive system according to claim 1, wherein determining a torque limit to limit a torque command to the one or more electric drive motors includes calculating a derivative of an engine speed based on the engine speed signal, the derivative of the engine speed being indicative of the acceleration or deceleration of the engine.

3. The method of load management within an electric drive system according to claim 2, wherein determining a torque limit to limit a torque command to the one or more electric drive motors further includes converting the derivative of the engine speed into an acceleration fuel rate.

4. The method of load management within an electric drive system according to claim 3, wherein the acceleration fuel rate is based at least in part on a moment of inertia of the engine.

5. The method of load management within an electric drive system according to claim 4, wherein determining a torque limit to limit a torque command to the one or more electric drive motors further includes calculating a minimum allowable fuel value indicative of a minimum fuel rate needed for continued operation of the engine.

6. The method of load management within an electric drive system according to claim 5, wherein determining a torque limit to limit a torque command to the one or more electric drive motors further includes calculating a maximum allowable fuel based on a lesser of a smoke limit fuel rate and a torque limit fuel rate, wherein the smoke limit fuel rate is a function of the intake air pressure signal and the engine speed signal, and wherein the torque limit fuel rate is a function of the engine speed signal.

7. The method of load management within an electric drive system according to claim 6, wherein determining a torque limit to limit a torque command to the one or more electric drive motors further includes calculating an actual power capacity of the engine by subtracting the acceleration fuel rate and the minimum fuel rate needed for continued operation of the engine from the actual fuel signal.

8. The method of load management within an electric drive system according to claim 7, wherein determining a torque limit to limit a torque command to the one or more electric drive motors further includes calculating a total theoretical fuel by subtracting the minimum fuel rate needed for continued operation of the engine from the actual fuel.

9. The method of load management within an electric drive system according to claim 8, wherein determining a torque limit to limit a torque command to the one or more electric drive motors further includes calculating an actual adjusted percent load signal by dividing an actual power with a total theoretical power that is based on the total theoretical fuel, wherein the actual power depends on the minimum fuel rate and the acceleration fuel rate.

10. The method of load management within an electric drive system according to claim 9, wherein determining a torque limit to limit a torque command to the one or more electric drive motors further includes calculating a theoretical adjusted percent load signal based on at least one of the engine speed, the throttle position signal, the motor speed signal, a gear position, a barometric pressure, and an intake manifold pressure.

11. The method of load management within an electric drive system according to claim 10, wherein determining a torque limit to limit a torque command to the one or more electric drive motors further includes deriving a maximum torque for the one or more electric drive motors based on a difference between the theoretical adjusted percent load signal and the actual adjusted percent load signal.