Systems and methods for monitoring operation of an led string

A device comprising:

• a string of LEDs;
• a circuit configured to supply current to the string of LEDs;
• a current measuring circuit configured to measure current through the string of LEDs;
• a voltage measuring circuit configured to measure voltage across the string of LEDs;
• a temperature sensor configured to measure temperature proximate to the string of LEDs;
• and
• a processor coupled to the circuit, the current measuring circuit, the voltage measuring circuit, a time accumulator circuit, and the temperature sensor, processor configured to:
• calculate a predicted LED string voltage based on a previously defined voltage-current (VI) curve, number of LEDs in the LED string, a previously defined temperature coefficient value, the measured LED string current, a measured LED junction temperature, a life curve function, a previously stored calibration string current value, a previously stored calibration string voltage value, a previously defined LED junction calibration temperature and an accumulated time value;
• measure voltage of the LED string;
• calculate an error value based on the predicted LED string voltage and the measured LED string voltage;
• determine if the error value is greater than the predefined error limit;
• and
• generate and output an indication that there is a failure in the LED string if the calculated error value is greater than the predefined error limit.

A method comprising:

• at a current measuring circuit, measuring current of a string of LEDs;
• at a voltage measuring circuit, measuring voltage of the LED string;
• at a processor:
• calculating a predicted LED string voltage based on a previously defined voltage-current (VI) curve, number of LEDs in the LED string, a previously defined temperature coefficient value, the measured LED string current, a measured LED junction temperature, a previously stored calibration string current value, a previously stored calibration string voltage value, a previously defined LED junction calibration temperature and an accumulated time value;
• calculating an error value based on the predicted LED string voltage and the measured LED string voltage;
• determining if the error value is greater than the predefined error limit;
• and
• outputting an indication that there is a failure in the LED string if the calculated error value is greater than the predefined error limit.