Predictive lighting control using load current slew rate for power switching
View Patent ↗An electronic device is described. The electronic device includes current measuring circuitry configured to measure load current to produce a load current measurement. The electronic device also includes a processor coupled to the current measuring circuitry. The processor is configured to calculate an estimated load current slope based on the load current measurement and to determine a predicted zero-cross point based on the estimated load current slope to minimize damaging voltage spike creation.
1. An electronic device, comprising:
current measuring circuitry configured to measure load current to produce a load current measurement; and
a processor coupled to the current measuring circuitry, wherein the processor is configured to calculate an estimated load current slope based on the load current measurement and to determine a predicted zero-cross point for the load current based on the estimated load current slope to minimize damaging voltage spike creation, and wherein the processor calculates a rolling average of the load current for a current sample point.
2. The electronic device of claim 1 , wherein the processor calculates the rolling average using at least ten sample points.
3. The electronic device of claim 1 , wherein the processor stores the rolling average in an average value array.
4. The electronic device of claim 3 , wherein the average value array comprises rolling averages for a number of sample points.
5. The electronic device of claim 1 , wherein the processor configured to calculate the estimated load current slope comprises the processor configured to:
determine an average load current difference between the rolling average for the current sample point and a rolling average for an earlier sample point; and
divide the average load current difference by a time interval between the current sample point and the earlier sample point.
6. The electronic device of claim 1 , wherein the processor configured to determine the predicted zero-cross point comprises the processor configured to:
add the rolling average of the load current for the current sample point to the estimated load current slope multiplied by a look-ahead value.
7. The electronic device of claim 6 , wherein the look-ahead value comprises a time interval to compensate for switching delays.
8. The electronic device of claim 1 , wherein the processor is further configured to determine that the predicted zero-cross point crosses an X-axis when the predicted zero-cross point changes sign.
9. The electronic device of claim 1 , wherein the processor causes at least one switch to be turned off at the predicted zero-cross point.
10. The electronic device of claim 9 , wherein the processor causes the at least one switch to be turned off when the predicted zero-cross point changes sign.
11. The electronic device of claim 9 , wherein the at least one switch comprises a first metal-oxide-semiconductor field-effect transistor (MOSFET).
12. A method, comprising:
measuring load current to produce a load current measurement;
calculating a rolling average of the load current for a current sample point;
calculating an estimated load current slope based on the load current measurement; and
determining a predicted zero-cross point for the load current based on the estimated load current slope to minimize damaging voltage spike creation.
13. The method of claim 12 , wherein calculating the estimated load current slope comprises:
determining an average load current difference between the rolling average for the current sample point and a rolling average for an earlier sample point; and
dividing the average load current difference by a time interval between the current sample point and the earlier sample point.
14. The method of claim 12 , wherein determining the predicted zero-cross point comprises:
adding the rolling average of the load current for the current sample point to the estimated load current slope multiplied by a look-ahead value.
15. The method of claim 12 , further comprising causing at least one switch to be turned off at the predicted zero-cross point.
16. The method of claim 15 , wherein the at least one switch is caused to be turned off when the predicted zero-cross point changes sign.
17. The method of claim 15 , wherein the at least one switch comprises a first metal-oxide-semiconductor field-effect transistor (MOSFET).
18. A non-transitory computer-readable medium, the computer-readable medium comprising executable instructions for:
measuring load current to produce a load current measurement;
calculating a rolling average of the load current for a current sample point;
calculating an estimated load current slope based on the load current measurement; and
determining a predicted zero-cross point for the load current based on the estimated load current slope to minimize damaging voltage spike creation.