Temperature control system for fuel cell electric vehicle cooling circuit

• US 6,651,761 B1
• Filed: 04/18/2002
• Issued: 11/25/2003
• Est. Priority Date: 09/27/2001
• Status: Active Grant

• Current Assignee: Ford Motor Company
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Schwartz, William Samuel, Asgari, Jahanbakhsh, Hrovat, Davorin David, Deur, Josko
• Primary Examiner(s): Johnson, Brian L.
• Assistant Examiner(s): SWENSON, BRIAN L
• Application Number:
  US10/063,400
• Time in Patent Office: 586 Days
• Field of Search: 429/24, 429/26, 180/65.1, 180/65.2, 180/65.3, 165/41, 165/42, 165/43, 123/41.12, 123/41.49
• US Class Current: 429/442
• CPC Class Codes: B60L 1/003 to auxiliary motors, e.g. for pumps, compressors
• CPC Class Codes: B60L 1/02 to electric heating circuits
• CPC Class Codes: B60L 15/20 for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/34 Cabin temperature
• CPC Class Codes: B60L 2240/36 Temperature of vehicle components or parts
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/662 Temperature
• CPC Class Codes: B60L 2260/56 Temperature prediction, e.g. for pre-cooling
• CPC Class Codes: B60L 2270/142 acoustic
• CPC Class Codes: B60L 2270/145 Structure borne vibrations
• CPC Class Codes: B60L 2270/44 Heat storages, e.g. for cabin heating
• CPC Class Codes: B60L 2270/46 Heat pumps, e.g. for cabin heating
• CPC Class Codes: B60L 3/0023 Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
• CPC Class Codes: B60L 3/0053 relating to fuel cells
• CPC Class Codes: B60L 50/72 Constructional details of fuel cells specially adapted for electric vehicles
• CPC Class Codes: B60L 58/33 by cooling
• CPC Class Codes: B60L 58/34 by heating
• CPC Class Codes: H01M 8/04014 Heat exchange using gaseous fluids; Heat exchange by combustion of reactants
• CPC Class Codes: H01M 8/04067 Heat exchange or temperature measuring elements, thermal insulation, e.g. heat pipes, heat pumps, fins
• CPC Class Codes: Y02E 60/50 : Fuel cells
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• 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
• CPC Class Codes: Y02T 90/40 : Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

A system and method to control the coolant temperature of two independent cooling loops of a fuel cell vehicle by adjusting system pump speed, fan speed and radiator bypass valve position. Multiple feedback controllers coordinated by robust flip-flop logic are used, to minimize energy consumption and provide optimal control system performance even in the case of substantially different plant responses with respect to fan speed and valve position plant inputs. The system also includes a feed forward disturbance compensator, which reacts immediately to change in net power and vehicle speed disturbance variables, thereby reducing the variance of the temperature control error. Additionally, a feedback controller preset strategy is used to compensate for distinctive plant nonlinear effects such as bypass valve dead-zone and air-conditioning system'"'"'s request for abrupt change of fan speed.

Claims

1. A temperature control system for a fuel cell vehicle having a fuel cell system and a plurality of electronic components, the fuel cell system and the electronic components each having optimal temperature operating limits, comprising:

sensors to determine temperature of the fuel cell system;

sensors to determine temperature of each of the electronic components;

a cooling system including a high temperature cooling circuit to cool the fuel cell system, and a low temperature cooling circuit to cool the electronic components, the cooling system further including a variable speed fan for cooling coolant flowing in the high and low temperature cooling circuits and a variable position radiator bypass valve for controlling the flow of coolant in the high temperature cooling circuit; and

a controller to simultaneously and separately control a high temperature cooling circuit and the low temperature cooling circuit to maintain optimal operating temperature limits of both the fuel cell system and the electronic components, the controller including overshoot and undershoot compensation based on controller preset actions and a logic circuit for coordinating the operation of the fan with the operation of the bypass valve such that fan speed is a function of the operating position of the bypass valve.

2. The system of claim 1, wherein the cooling circuits comprise a variable speed coolant pump to maintain optimal operating temperature limits of the fuel cell system and the electronic components.

3. The system of claim 1, wherein the controller comprises:

a first fast response controller to maintain a coolant at a high temperature coolant circuit fuel cell system inlet to a first predetermined coolant temperature;

a second fast response controller to maintain the coolant temperature difference between a high temperature coolant circuit fuel cell system outlet and the high temperature coolant circuit fuel cell system inlet to a second predetermined coolant value; and

a third fast response controller to maintain the coolant temperature within a low temperature coolant circuit to a third predetermined coolant temperature when coolant temperature exceeds the third predetermined temperature.

4. The system of claim 3, wherein the first predetermined fuel cell system inlet coolant temperature is 70 degrees Celsius, +2 degrees.

5. The system of claim 3 wherein the second predetermined coolant value is approximately 10 degrees Celsius.

6. The system of claim 3 wherein the third predetermined coolant temperature is approximately 50 degrees Celsius.

7. The system of claim 3 wherein the fast response controllers are proportional integral controllers.

8. The system of claim 1 wherein the plurality of electronic components comprise auxiliary fuel cell system components, electric drivetrain components, and power management hardware.

9. The system of claim 1 wherein the controller uses feed-forward disturbance compensation to reduce coolant temperature spikes comprising measured signals for fuel cell output power and vehicle speed, and control strategies to reduce coolant temperature dynamic control errors, and control errors caused by a bypass valve dead-zone effect.

10. The strategy of claim 9 wherein the control strategies to reduce coolant temperature dynamic control errors comprise overshoot compensation and undershoot compensation based on controller preset actions.

11. The strategy of claim 9 wherein the feed-forward control strategies comprise a control strategy to measure fuel cell power output and vehicle speed disturbance variables, and vary fan speed or bypass valve position to compensate immediately for the disturbance effect.

12. The system of claim 3 wherein the first fast response controller controls bypass valve position and fan speed, the second fast response controller controls pump speed, and the third fast response controller controls fan speed.

13. The system of claim 12 wherein the first fast response controller controls, in sequence, the bypass valve position until fully opened to deliver coolant to a first radiator, then flip-flops to fan speed control, then flip flops back to bypass valve position control if the commanded fan speed reaches a lower limit or if the third fast response controller is activated when a second radiator inlet temperature exceeds an upper limit.

14. The system of claim 13 further comprising an air-conditioning (A/C) system having an A/C condenser exposed to a cooling airflow, the A/C system using the same fan as the temperature control system, wherein a final fan speed is given by a maximum value of the speeds requested by the control system and the A/C system, wherein the first fast response controller flip flops from fan speed control to bypass valve position control if the A/C system commands the fan speed higher than that of the first fast response controller.

15. A fuel cell powered vehicle comprising:

a fuel cell system serving as a power source;

an electric drive train powered by the fuel cell system;

a plurality of electronic components; and

a temperature control system for the fuel cell system and plurality of electronic components, the fuel cell system and the electronic components each having optimal temperature operating limits, the control system including

sensors to determine temperature of the fuel cell system,

sensors to determine temperature of each of the electronic components,

a high temperature cooling circuit to cool the fuel cell system,

a low temperature cooling circuit to cool the electronic components,

a variable speed fan for cooling coolant flowing in the high and low temperature cooling circuits,

a variable position radiator bypass valve for controlling the flow of coolant in the high temperature cooling circuit, and

a controller for simultaneously and separately controlling the high and low temperature cooling circuits to maintain optimal operating temperature limits of both the fuel cell system and the electronic components, the controller including overshoot and undershoot compensation based on controller preset action and a logic circuit for coordinating the operation of the fan with the bypass valve such that the speed of the fan is dependent on the operating position of the bypass valve.

16. A method of controlling temperature of a fuel cell system and a plurality of electronic components in a fuel cell vehicle, the fuel cell system and the electronic components each having optimal temperature operating limits, comprising the steps of:

determining temperature of the fuel cell system;

determining temperature of each of the electronic components; and

controlling simultaneously and separately a high temperature cooling circuit to cool the fuel cell system and

a low temperature cooling circuit to cool the electronic components to maintain optimal operating temperature limits of both the fuel cell system and the electronic components, including overshoot and undershoot compensation based on controller preset actions and

controlling the operating position of a variable position bypass valve used to control the flow of coolant in the high temperature cooling circuit, and

controlling the speed of a fan used to cool coolant flowing in the high and low temperature cooling circuits based on the operating position of the bypass valve.

17. The method of claim 16, wherein the step of controlling simultaneously and separately the high temperature cooling circuit to cool the fuel cell system and the low temperature cooling circuit to cool the electronic components comprises the steps of:

controlling a first fast response to maintain a coolant at a high temperature coolant circuit fuel cell system inlet to a first predetermined coolant temperature;

controlling a second fast response to maintain the coolant temperature difference between a high temperature coolant circuit fuel cell system outlet and the high temperature coolant circuit fuel cell fuel cell system inlet to a second predetermined coolant value; and

controlling a third fast response to maintain the coolant temperature within the low temperature coolant circuit to a third predetermined coolant temperature when coolant temperature exceeds the third predetermined temperature.

18. The method of claim 17, wherein the first predetermined fuel cell system inlet coolant temperature is 70 degrees Celsius, +2 degrees.

19. The method of claim 17 wherein the second predetermined coolant value is approximately 10 degrees Celsius.

20. The method of claim 17 wherein the third predetermined coolant temperature is approximately 50 degrees Celsius.

21. The method of claim 17 wherein the step of controlling fast responses uses proportional integral controllers.

22. The method of claim 16 wherein the plurality of electronic components comprise auxiliary fuel cell system components, electric drivetrain components, and power management hardware.

23. The method of claim 16 wherein the step of controlling simultaneously and separately the cooling circuits comprises the steps of:

compensating feed-forward disturbance to reduce coolant temperature spikes comprising measuring signals for fuel cell output power and vehicle speed;

reducing coolant temperature dynamic control errors; and

controlling errors caused by a bypass valve dead-zone effect.

24. The method of claim 23 wherein the step of reducing coolant temperature dynamic control errors comprise the steps of overshooting compensation and undershooting compensation based on controller preset actions.

25. The method of claim 23 wherein the step of compensating feed-forward disturbance comprises the steps of measuring fuel cell power output and vehicle speed disturbance variables, and varying fan speed or bypass valve position to compensate immediately for the disturbance effect.

26. The method of claim 17 wherein the first fast response controller controls bypass valve position and fan speed, the second fast response controller controls pump speed, and the third fast response controller controls fan speed.

27. The method of claim 26 wherein the step of controlling a first fast response comprises the steps of controlling, in sequence, the bypass valve position until fully opened to deliver coolant to a first radiator, then flip-flops to controlling fan speed, then flip flops back to controlling bypass valve position if the commanded fan speed reaches a lower limit or if the step of controlling a third fast response is activated when a second radiator inlet temperature exceeds an upper limit.

30. The system of claim 25 wherein the feed-forward control strategies comprise a control strategy to measure fuel cell power output and vehicle speed disturbance variables, and vary fan speed or bypass valve position to compensate immediately for the disturbance effect.

28. A temperature control system for a fuel cell vehicle having a fuel cell system and a plurality of electronic components, the fuel cell system and the electronic components each having optimal temperature operating limits, comprising:

sensors to determine temperature of the fuel cell system;

sensors to determine temperature of each of the electronic components; and

a controller to simultaneously and separately control a high temperature cooling circuit to cool the fuel cell system and a low temperature cooling circuit to cool the electronic components, the controller maintaining optimal operating temperature limits of both the fuel cell system and the electronic components, the controller including

(a) a first fast response controller to maintain a coolant at a high temperature coolant circuit fuel cell system inlet to a first predetermined coolant temperature,

(b) a second fast response controller to maintain the coolant temperature difference between a high temperature coolant circuit fuel cell system outlet and the high temperature coolant circuit fuel cell system inlet to a second predetermined coolant value, and

(c) a third fast response controller to maintain the coolant temperature within a low temperature coolant circuit to a third predetermined coolant temperature when coolant temperature exceeds the third predetermined temperature,

wherein the fast response controllers are proportional integral controllers.

29. A temperature control system for a fuel cell vehicle having a fuel cell system and a plurality of electronic components, the fuel cell system and the electronic components each having optimal temperature operating limits, comprising:

sensors to determine temperature of the fuel cell system;

sensors to determine temperature of each of the electronic components; and

a controller to simultaneously and separately control a high temperature cooling circuit to cool the fuel cell system and a low temperature cooling circuit to cool the electronic components, the controller maintaining optimal operating temperature limits of both the fuel cell system and the electronic components, the controller using feed-forward disturbance compensation to reduce coolant temperature spikes comprising measured signals for fuel cell output power and vehicle speed, and control strategies to reduce coolant temperature dynamic control errors, and control errors caused by a bypass valve dead-zone effect, the control strategies including overshoot compensation and undershoot compensation based on controller preset actions.

31. A temperature control system for a fuel cell vehicle having a fuel cell system and a plurality of electronic components, the fuel cell system and the electronic components each having optimal temperature operating limits, comprising:

sensors to determine temperature of the fuel cell system;

sensors to determine temperature of each of the electronic components; and

a controller to simultaneously and separately control a high temperature cooling circuit to cool the fuel cell system and a low temperature cooling circuit to cool the electronic components, the controller maintaining optimal operating temperature limits of both the fuel cell system and the electronic components, the controller including

(a) a first fast response controller to maintain a coolant at a high temperature coolant circuit fuel cell system inlet to a first predetermined coolant temperature, and to control bypass valve position and fan speed, the first fast response controller controlling, in sequence, the bypass valve position until fully opened to deliver coolant to a first radiator, then flip-flops to fan speed control, then flip flops back to bypass valve position control if the commanded fan speed reaches a lower limit or if the third fast response controller is activated when a second radiator inlet temperature exceeds an upper limit,

(b) a second fast response controller to maintain the coolant temperature difference between a high temperature coolant circuit fuel cell system outlet and the high temperature coolant circuit fuel cell system inlet to a second predetermined coolant value, and to control pump speed, and

(c) a third fast response controller to control fan speed and to maintain the coolant temperature within a low temperature coolant circuit to a third predetermined coolant temperature when coolant temperature exceeds the third predetermined temperature.

32. The system of claim 31 further comprising an air-conditioning (A/C) system having an A/C condenser exposed to a cooling airflow, the A/C system using the same fan as the temperature control system, wherein a final fan speed is given by a maximum value of the speeds requested by the control system and the A/C system, wherein the first fast response controller flip flops from fan speed control to bypass valve position control if the A/C system commands the fan speed higher than that of the first fast response controller.

33. A method of controlling temperature of a fuel cell system and a plurality of electronic components in a fuel cell vehicle, the fuel cell system and the electronic components each having optimal temperature operating limits, comprising the steps of:

determining temperature of the fuel cell system;

determining temperature of each of the electronic components; and

controlling simultaneously and separately a high temperature cooling circuit to cool the fuel cell system and a low temperature cooling circuit to cool the electronic components to maintain optimal operating temperature limits of both the fuel cell system and the electronic components, the step of controlling the cooling circuits being performed by

(a) controlling a first fast response proportional integral controller to maintain a coolant at a high temperature coolant circuit fuel cell system inlet to a first predetermined coolant temperature,

(b) controlling a second fast response proportional integral controller to maintain the coolant temperature difference between a high temperature coolant circuit fuel cell system outlet and the high temperature coolant circuit fuel cell fuel cell system inlet to a second predetermined coolant value, and

(c) controlling a third fast response proportional integral controller to maintain the coolant temperature within the low temperature coolant circuit to a third predetermined coolant temperature when coolant temperature exceeds the third predetermined temperature.

34. A method of controlling temperature of a fuel cell system and a plurality of electronic components in a fuel cell vehicle, the fuel cell system and the electronic components each having optimal temperature operating limits, comprising the steps of:

determining temperature of the fuel cell system;

determining temperature of each of the electronic components; and

controlling simultaneously and separately a high temperature cooling circuit to cool the fuel cell system and a low temperature cooling circuit to cool the electronic components to maintain optimal operating temperature limits of both the fuel cell system and the electronic components, the step of controlling the cooling circuits being performed by

(a) compensating feed-forward disturbance to reduce coolant temperature spikes comprising measuring signals for fuel cell output power and vehicle speed,

(b) reducing coolant temperature dynamic control errors by overshooting compensation and undershooting compensation based on controller preset actions, and

(c) controlling errors caused by a bypass valve dead-zone effect.

35. A method of controlling temperature of a fuel cell system and a plurality of electronic components in a fuel cell vehicle, the fuel cell system and the electronic components each having optimal temperature operating limits, comprising the steps of:

determining temperature of the fuel cell system;

determining temperature of each of the electronic components; and

controlling simultaneously and separately a high temperature cooling circuit to cool the fuel cell system and a low temperature cooling circuit to cool the electronic components to maintain optimal operating temperature limits of both the fuel cell system and the electronic components, the step of controlling the cooling circuits being performed by

(a) controlling a first fast response controller to maintain a coolant at a high temperature coolant circuit fuel cell system inlet to a first predetermined coolant temperature,

(b) controlling a second fast response controller to maintain the coolant temperature difference between a high temperature coolant circuit fuel cell system outlet and the high temperature coolant circuit fuel cell fuel cell system inlet to a second predetermined coolant value, and

(c) controlling a third fast response controller to maintain the coolant temperature within the low temperature coolant circuit to a third predetermined coolant temperature when coolant temperature exceeds the third predetermined temperature,

wherein the first fast response controller controls bypass valve position and fan speed, the second fast response controller controls pump speed, and the third fast response controller controls fan speed.

36. A temperature control system for a fuel cell vehicle having a fuel cell system and a plurality of electronic components, the fuel cell system and the electronic components each having optimal temperature operating limits, comprising:

sensors to determine temperature of the fuel cell system;

sensors to determine temperature of each of the electronic components; and

a controller to simultaneously and separately control a high temperature cooling circuit to cool the fuel cell system and a low temperature cooling circuit to cool the electronic components, the controller maintaining optimal operating temperature limits of both the fuel cell system and the electronic components, the controller including overshoot and undershoot compensation based on controller preset actions for reducing coolant temperature control errors.

37. The system of claim 36, wherein the controller includes:

a first fast response controller to maintain a coolant at a high temperature coolant circuit fuel cell system inlet to a first predetermined coolant temperature,

a second fast response controller to maintain the coolant temperature difference between a high temperature coolant circuit fuel cell system outlet and the high temperature coolant circuit fuel cell system inlet to a second predetermined coolant value, and

a third fast response controller to maintain the coolant temperature within a low temperature coolant circuit to a third predetermined coolant temperature when coolant temperature exceeds the third predetermined temperature.

38. The system of claim 37, wherein the fast response controllers are proportional integral controllers.

39. The system of claim 37, wherein the first fast response controller controls bypass valve position and fan speed, the second fast response controller controls pump speed, and the third fast response controller controls fan speed.

40. The system of claim 39, wherein the first fast response controller controls, in sequence, the bypass valve position until fully opened to deliver coolant to a first radiator, then flip-flops to fan speed control, then flip flops back to bypass valve position control if the commanded fan speed reaches a lower limit or if the third fast response controller is activated when a second radiator inlet temperature exceeds an upper limit.

41. The system of claim 36, wherein the controller includes feed-forward disturbance compensation for reducing coolant temperature spikes.

42. The system of claim 39, wherein the feed-forward disturbance compensation includes measured signals for fuel cell output power and vehicle speed.

43. A method of controlling temperature of a fuel cell system and a plurality of electronic components in a fuel cell vehicle, the fuel cell system and the electronic components each having optimal temperature operating limits, comprising the steps of:

determining temperature of the fuel cell system;

determining temperature of each of the electronic components; and

controlling simultaneously and separately a high temperature cooling circuit to cool the fuel cell system and a low temperature cooling circuit to cool the electronic components to maintain optimal operating temperature limits of both the fuel cell system and the electronic components, the step of controlling the cooling circuits including reducing coolant temperature dynamic control errors by overshooting compensation and undershooting compensation based on present controller actions.