Method and apparatus for cooling system failure detection

• US 20060021358A1
• Filed: 12/03/2004
• Published: 02/02/2006
• Est. Priority Date: 07/30/2004
• Status: Active Grant

• Current Assignee: Siemens VDO Automotive Corporation (Siemens AG)
• Original Assignee: Siemens VDO Automotive Corporation (Siemens AG)
• Inventors: Nallapa, Venkatapathi Raju
• Granted Patent: US 7,484,377 B2
• Time in Patent Office: Days
• US Class Current: 62/126
• CPC Class Codes: F25B 49/005 of safety devices F25B49/02 and F25B49/04 take precedence
• CPC Class Codes: H02K 9/24 Protection against failure of cooling arrangements, e.g. due to loss of cooling medium or due to interruption of the circulation of cooling medium
• CPC Class Codes: H02P 29/02 Providing protection against overload without automatic interruption of supply protection against faults of stepper motors H02P8/36

Abstract

A system and method for detecting failure of a cooling system in an alternating current machine, such as a motor and/or a generator. For example, in one embodiment energy wasting is initiated and a failure is indicated if a temperature rises by more than a selected amount over a selected time period.

Claims

1. A control system for controlling a machine, the control system comprising:

a current control subsystem to generate current control signals;

a cooling system control subsystem to generate cooling system control signals;

a sensor system to sense an operating condition of the machine; and

a cooling system failure detection subsystem communicatively coupled to the current control subsystem, the cooling system control subsystem and the sensor system, wherein the cooling system failure detection subsystem is configured to;

selectively initiate a cooling system failure detection cycle;

generate a control signal to cause generation of waste heat in the machine during the cooling system failure detection cycle;

monitor the sensor system during the cooling system failure detection cycle; and

terminate the cooling system failure detection cycle and generate a signal indicating a failure, if the monitoring of the sensor system indicates a change in the sensed operating condition exceeds a threshold value.

2. The control system of claim 1 wherein the cooling system failure detection subsystem is further configured to terminate the cooling system failure detection cycle and generate a signal indicating no failure, if the monitoring of the sensor system indicates a selected period of time has elapsed since the cooling system failure detection cycle was initiated and the cooling system failure detection cycle was not previously terminated.

3. The control system of claim 1 wherein the cooling system failure detection subsystem is configured to generate a control signal to cause generation of waste heat by generating a control signal causing the current control subsystem to generate a control signal to increase a flux current.

4. The control system of claim 1 wherein the operating condition of the machine is a temperature.

5. The control system of claim 1 wherein the operating condition of the machine is an average of a plurality of temperatures.

6. The control system of claim 1 wherein the operating condition of the machine is a selected one of a plurality of temperatures.

7. The control system of claim 1 wherein the cooling system failure detection subsystem is further configured to disable initiation of the cooling system failure detection cycle when the current control subsystem is generating a current control signal to generate a torque current.

8. The control system of claim 1 wherein the cooling system failure detection subsystem is configured to initiate the cooling system failure detection cycle in response to a command issued by an external test controller.

9. A machine comprising:

a rotor; and

a control system for controlling the alternating current machine, the control system comprising;

a current control subsystem to generate current control signals;

a cooling system control subsystem to generate cooling system control signals;

a sensor system to sense an operating condition of the machine; and

a cooling system failure detection subsystem communicatively coupled to the current control subsystem, the cooling system control subsystem and the sensor system, wherein the cooling system failure detection subsystem is configured to;

selectively initiate a cooling system failure detection cycle;

generate a control signal to cause generation of waste heat in the machine during the cooling system failure detection cycle;

monitor the sensor system during the cooling system failure detection cycle;

terminate the cooling system failure detection cycle and generate a signal indicating a failure, if the monitoring of the sensor system indicates a change in the sensed operating condition exceeds a threshold value; and

terminate the cooling system failure detection cycle and generate a signal indicating no failure, if the monitoring of the sensor system indicates a selected period of time has elapsed since the cooling system failure detection cycle was initiated and the cooling system failure detection cycle was not previously terminated.

10. The machine of claim 9 wherein the sensor system comprises an encoder to generate a signal indicating movement of the rotor and the control system is configured to disable the cooling system failure detection subsystem if the signal indicating movement of the rotor indicates movement of the rotor.

11. The machine of claim 9 wherein the cooling system failure detection subsystem is configured to generate a control signal to cause generation of waste heat by generating a control signal causing the current control subsystem to generate a control signal to increase a flux current.

12. The machine of claim 11 wherein the machine is configured to respond to the control signal to increase a flux current by increasing the flux current by approximately 300 amps.

13. The machine of claim 9 wherein cooling system failure detection subsystem is configured to generate a control signal to cause generation of waste heat by generating a control signal causing the current control subsystem to couple a shunt resistor across a voltage.

14. A method of detecting a failure of a cooling system in a machine, the method comprising:

selectively initiating a test cycle;

generating waste heat in the alternating current machine during the test cycle;

monitoring a condition of the alternating current machine during the test cycle;

terminating the test cycle and indicating a failure, if the monitored condition is outside a selected threshold range; and

terminating the test cycle and indicating no failure, if a selected period of time has elapsed since the test cycle was initiated and the test cycle was not previously terminated.

15. The method of claim 14 wherein monitoring a condition of the alternating current machine during the test cycle comprises monitoring a change in a temperature.

16. The method of claim 15 wherein the selected threshold range is a change in temperature of less than five degrees Celsius.

17. The method of claim 14 wherein generating waste heat comprises generating an excess flux current.

18. The method of claim 14, further comprising disabling initiation of the test cycle if a torque current is being generated.

19. The method of claim 14 wherein monitoring a condition of the alternating current machine comprises monitoring a plurality of thermal sensors.

20. The method of claim 14, wherein the machine is an electric vehicle.

21. The method of claim 14, further comprising disabling initiation of the test cycle if movement of a rotor of the machine is detected.

22. The method of claim 14 wherein the test cycle is initiated in response to a command received from an external test controller.

23. The method of claim 14 wherein the selected period of time has a duration of approximately thirty seconds.

24. The method of claim 14, further comprising generating control signals in response to an indication of a failure.

25. A control system comprising:

means for cooling a machine;

means for controlling a rotatable component of the machine; and

means for detecting a failure of the means for cooling a machine, communicatively coupled to the means for controlling a rotatable component of the machine, wherein the means for detecting a failure of the means for cooling a machine is configured to;

selectively generate a control signal causing the means for controlling a rotatable component of the machine to generate waste heat in the machine; and

monitor a response of the machine to the generated waste heat.

26. The control system of claim 25 wherein the means for controlling a rotatable component of the machine is configured to generate waste heat in the machine by increasing a flux current.

27. The control system of claim 25 wherein the means for detecting a failure of the means for cooling a machine is configured to generate a signal indicating the means for cooling a machine is functioning properly if the monitored response of the machine is within a selected threshold response.

28. The control system of claim 27 wherein the monitored response is a change in a temperature.

29. A computer-readable medium storing instructions for causing a control system to facilitate detection of a failed cooling system in an alternating current machine by:

selectively initiating a test cycle;

generating waste heat in the alternating current machine during the test cycle;

monitoring a condition of the alternating current machine during the test cycle;

terminating the test cycle and indicating a failure, if the monitored condition is outside a selected threshold range; and

terminating the test cycle and indicating no failure, if a selected period of time has elapsed since the test cycle was initiated and the test cycle was not previously terminated.

30. The computer-readable medium of claim 29 wherein generating waste heat comprises generating an excess flux current.