Electronic ballast with power thermal cutback

A method, comprising:

• causing a PFC converter of an electronic ballast to receive a PFC input voltage and to provide a DC bus voltage at a DC bus;
• causing a DC/AC converter of the electronic ballast to receive the DC bus voltage and to provide AC power to a lamp at an AC output frequency;
• causing a compensator to provide a compensator signal to the PFC converter or the DC/AC converter, wherein the compensator is responsive to an electronic ballast condition parameter and the compensator comprises:
• a Zener diode, a voltage divider having a first resistor and a second resistor, and a transistor circuit having a transistor operably connected in series with a negative temperature coefficient thermal resistor, the transistor having an emitter operably connected to the negative temperature coefficient thermal resistor and a base operably connected between the first resistor and the second resistor, wherein the Zener diode, the voltage divider, and the transistor circuit are operably connected in parallel between the DC bus and a common;
• and
• when the electronic ballast condition parameter satisfies an electronic ballast condition parameter threshold:
• causing the PFC converter or the DC/AC converter to respond to the compensator signal to reduce a power output of the electronic ballast, wherein the electronic ballast condition parameter is an electronic ballast temperature, the compensator signal is a DC bus adjust signal, and the PFC converter responds to the DC bus adjust signal by reducing the DC bus voltage as a result of the electronic ballast temperature satisfying the electronic ballast condition parameter threshold.

An electronic ballast for providing power to a lamp, the electronic ballast comprising:

• a PFC converter configured to receive a PFC input voltage and to provide a DC bus voltage at a DC bus;
• a DC/AC converter configured to receive the DC bus voltage from the DC bus and to provide AC power to the lamp at an AC output frequency;
• and
• a compensator responsive to an electronic ballast condition parameter, the compensator being configured to provide a compensator signal to at least one of the PFC converter and the DC/AC converter, the compensator comprising a Zener diode circuit having a Zener diode and a transistor connected in series, and a resistor circuit having a negative temperature compensation resistor,
• wherein the at least one of the PFC converter and the DC/AC converter responds to the compensator signal to reduce the power to the lamp when the electronic ballast condition parameter passes an electronic ballast condition parameter threshold,
• wherein the electronic ballast condition parameter is an electronic ballast temperature, the compensator signal is a DC bus adjust signal, and the PFC converter is responsive to the DC bus adjust signal to reduce the DC bus voltage when the electronic ballast temperature is greater than a threshold electronic ballast temperature, and
• wherein:
• the transistor of the Zener diode circuit has a base operably connected to the negative temperature compensation resistor;
• and
• the Zener diode circuit and the resistor circuit are connected in parallel between a fixed voltage and common.