Integrated Circuit and Method for Classification of Electrical Devices and Short Circuit Protection

• US 20080208491A1
• Filed: 02/28/2008
• Published: 08/28/2008
• Est. Priority Date: 02/28/2007
• Status: Active Grant

• Current Assignee: STMicroelectronics Incorporated (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Incorporated (STMicroelectronics NV)
• Inventors: Mirowski, Marian, Burlak, Gary Joseph
• Granted Patent: US 7,904,260 B2
• Time in Patent Office: Days
• US Class Current: 702/58
• CPC Class Codes: H02H 3/12 responsive to underload or no-load for motors H02H7/0827

Abstract

An integrated circuit device and method for classifying electrical devices is disclosed. A reference current response of a plurality of electrical devices is determined and stored in a memory. Real-time current response of a specific electrical device is measured and stored in the memory. A processor compared the measured real-time current response of the specific electrical device to the reference current responses of the plurality of electrical devices. A classification of the electrical device is then made based on the comparison.

Claims

1. A method for classifying electrical devices each receiving power from an output port of a respective power control circuit coupled to a battery, comprising:

storing a reference current responses of the electrical devices in a memory;

measuring a real-time current response of a specific electrical device;

storing the measured real-time current response of the specific electrical device in the memory;

comparing, by a processor, the measured real-time current response of the specific electrical device to the reference current responses of the plurality of electrical devices; and

classifying the electrical device based on the comparison.

2. The method according to claim 1, wherein the measured real-time current response includes a real-time in-rush current as a function of time.

3. The method according to claim 1, further comprising:

calculating the steady state current from the measured current response;

determining if the measured in-rush current is similar to the reference in-rush current;

if the measured in-rush current is similar to the reference in-rush current, assigning a potential first classification to the specific electrical device, the assigned potential first classification indicating that the specific electrical device may potentially be a first type of electrical device subject to validation;

determining if the steady state current is similar to the reference steady state current;

if the steady state current is similar to the reference steady state current, assigning a potential second classification to the specific electrical device, the assigned potential second classification indicating that the specific electrical device may potentially be a second type of electrical device subject to validation;

comparing the assigned first classification to the assigned second classification;

if the assigned first and second classifications are same, assigning a valid classification to the specific electrical device, the valid classification identifying the specific electrical device-type; and

reporting, by the processor, the valid classification.

4. The method according to claim 3, further comprising reporting an invalid classification if the assigned first and second classifications are different.

5. The method according to claim 1, wherein the power control circuit, the processor and the memory are implemented in a trailer tow connector configured to deliver power to the plurality of electrical devices installed in a trailer attached to a vehicle.

6. The method according to claim 4, wherein the trailer tow connector reports the classification of the electrical devices installed in the trailer via a vehicle communication network.

7. The method according to claim 1, further comprising:

classifying the plurality of electrical devices each receiving power from the battery; and

identifying a trailer-type based on the classification of the plurality of electrical devices.

8. The method according to claim 1, wherein the classification identifies the electrical devices as an incandescent bulb, a gas discharge bulb, an LED, or a battery.

9. The method according to claim 1, further comprising:

determining the maximum threshold current for the output port to which the electrical device is connected, the maximum threshold current being the short circuit current limit at the output port and being based on the characteristic of the output port;

storing the maximum threshold current value in the memory;

measuring the steady state current flowing in the electrical device for pre-selected times;

storing the steady state current values in the memory;

calculating, by the processor, a learned short circuit threshold current value from the steady state current values, the learned short circuit current value being less than the maximum threshold current value;

storing the learned short circuit current value in the memory;

measuring a real-time steady state current flowing in the electrical device;

comparing the measured real-time steady state current to the maximum threshold current and to the learned short circuit current;

if the measured real-time steady state current is greater than the maximum threshold current, reporting a possible hard short circuit condition at the output port;

if the measured real-time steady state current is more than the learned short circuit current but less than the maximum threshold current, reporting a possible soft short circuit condition at the output port.

10. The method according to claim 9, wherein the calculation of the learned short circuit current value comprises:

calculating, by the processor, an average steady state current value;

storing the average steady state current value in the memory;

determining the learned short circuit current value by multiplying the average steady state current value with a pre-selected percentage.

11. The method according to claim 9, wherein the pre-selected percentage is less than 100%.

12. The method according to claim 9, further comprising:

repeating measurement of the real-time steady state current flowing in the electrical device; and

comparing the measured real-time steady state current to the maximum threshold current and to the learned short circuit current.

13. The method according to claim 12, further comprising:

incrementing a first counter if the measured real-time steady state current is greater than the maximum threshold current; and

reporting a valid hard short circuit condition if the count value of the first counter exceeds a first count.

14. The method according to claim 12, further comprising:

incrementing a second counter if the measured real-time steady state current is more than the learned short circuit current but less than the maximum threshold current; and

reporting a valid soft short circuit condition if the count value of the second counter exceeds a second count.

15. The method according to claim 13, further comprising removing power from the output port by reducing duty cycle of the power control circuit responsive to the valid hard short condition.

16. An integrated circuit device for classifying electrical devices each receiving power from an output port of a respective power control circuit coupled to a battery, comprising:

a memory configured to store a reference current response and a measured real-time current response;

a processor electrically coupled to the memory;

a switched power control circuit electrically coupled to the electrical device, the switched power control circuit controlling the power delivered to the electrical device by varying a duty cycle responsive to a power control signal from the processor;

a current sense circuit electrically coupled to the load, the current sense circuit measuring the current flowing in the load and providing a current sense signal representative of the measured current to the processor; and

the processor classifying the electrical device by comparing a stored reference current response to a measured real-time current response.

17. The integrated circuit device of claim 16, wherein the power control signal is a pulse width modulated signal for controlling the duty cycle of the switched power control circuit.

18. The integrated circuit device of claim 16, further comprising decreasing, by the processor, the duty cycle of the switched power control circuit responsive to the current sense signal indicating a short circuit condition at the output port.

19. The integrated circuit device of claim 16, wherein the power control circuit, the processor and the memory are implemented in a trailer tow connector configured to regulate power in one or more electrical devices installed in a trailer attached to a vehicle.

20. The integrated circuit device of claim 16, wherein the battery is installed in a vehicle adapted to tow a trailer and wherein the power control circuit, the processor and the memory are implemented in a trailer tow connector.

21. A method for identifying a short circuit state at an output port of a trailer tow connector having a plurality of output ports each configured to provide power to an electrical device, the trailer tow connector having a processor coupled to a memory, the electrical device being installed in a trailer attached to a vehicle, the method comprising:

(1) determining a learned short circuit current value of the output port, the learned short circuit current value being based on a plurality of measured steady state learn-phase load currents at the output port, the learn-phase load currents being continually determined while a load is connected;

(2) storing the learned short circuit current value in the memory;

(3) measuring the load current at the output port;

(4) storing the measured load current value in the memory;

(7) comparing the load current value to the learned short circuit current value; and

(8) identifying the short circuit condition based on the comparison.

22. The method according to claim 21, wherein the load current is the steady state current.

23. The method according to claim 21, wherein the load current is the average value of a plurality of sampled current values.

24. The method according to claim 21, wherein the determination of the learned short circuit current further comprises:

measuring the steady state learn-phase load current at the output port for a selected number of times at selected time intervals;

storing the measured steady state learn-phase load current values in the memory;

selecting, by the processor, a subset of the steady state learn-phase load current values;

generating the learned short circuit current from the average of the subset of the steady state learn-phase current values.