Electronic ballast with closed loop control using composite current and voltage feedback and method thereof

The method of operation of an electronic ballast to regulate power to a load, comprising:

• A. The ballast incorporating an integrated circuit (IC) having a driving terminal, the integrated circuit being adapted to generate a train of high-frequency drive pulses at said driving terminal;
• a feedback terminal and an-internal reference voltage;
• the integrated circuit comparing a composite feedback signal received at its feedback terminal with the reference voltage and to adjusting the drive pulses accordingly to minimize the error of said comparison;
• B. The ballast further containing a bridge connected between the drive terminal and the load, the bridge being driven by drive signals and generating symmetric polarity-reversal power to the load;
• C. The ballast further comprising a feedback system connected to the feedback terminal and to the load, the feedback system deriving an average current feedback signal from current consumed by the load and deriving a voltage feedback signal from voltage consumed by the load;
• the feedback system combining, by addition, the current and voltage feedback signals and providing said composite feedback signal to the feedback terminal.

An electronic ballast to regulate power to a load, comprising:

• A. An integrated circuit (IC) means having a driving terminal to generate a train of drive pulses at said driving terminal;
• a feedback terminal and an internal reference voltage;
• the integrated circuit means to compare a feedback signal received at its feedback terminal with the reference voltage and to adjust the drive pulses to minimize the error of said comparison;
• B. a bridge means connected to the drive terminal and to the load, the bridge being driven by separate drive signals to generate low-frequency Polarity-reversal of the load;
• C. a feedback system means connected to the feedback terminal and to the load, the feedback system means to derive an average current feedback signal from current consumed by the load and to derive a voltage feedback signal from voltage applied to the load;
• the feedback system combining, by addition, the current and voltage feedback signals to provide said composite feedback signal to the feedback terminal.