Fluorescent Lamp Power Supply

Abstract

Various embodiments of a fluorescent lamp power supply are disclosed herein. In one embodiment, a power supply includes a power input connected to a pulse generator. The power supply also includes a filter connected to a variable pulse width output on the pulse generator and to the power input. The filter is adapted to substantially block at least one harmonic frequency component of the variable pulse width output and to substantially pass a fundamental frequency component of the variable pulse width output. The power supply also includes a power output connected to the filter, wherein an amplitude at the power output is related to the pulse width at the variable pulse width output.

What is claimed is: 
     
         1 . A power supply, comprising:
 a power input;   a power output;   a transformer having a primary winding connected to the power input and a secondary winding connected to the power output;   a switch connected in series with the primary winding;   a gate drive circuit connected to the switch and operable to control a current through the transformer;   a feedback signal from a secondary winding side of the power supply to the primary winding side of the power supply, wherein the gate drive circuit is controlled at least in part based on the feedback signal; and   a dimming sense and control circuit connected to the gate drive circuit, wherein the dimming sense and control circuit is adapted to reduce a current to the power output.   
     
     
         2 . The power supply of  claim 1 , wherein the dimming sense and control circuit comprises an external control signal input operable to receive an external control signal to control a dimming level. 
     
     
         3 . The power supply of  claim 2 , wherein the external control signal input comprises a wireless input. 
     
     
         4 . The power supply of  claim 2 , wherein the external control signal input comprises a wired input. 
     
     
         5 . The power supply of  claim 1 , wherein the dimming sense and control circuit is adapted to reduce the current to the power output based at least in part on a power level at the power input. 
     
     
         6 . The power supply of  claim 5 , wherein the dimming sense and control circuit is adapted to reduce the current to the power output based at least in part on a power level at the power input that as it is reduced by an external triac-based dimmer. 
     
     
         7 . The power supply of  claim 1 , wherein the gate drive circuit is operable to prioritize the feedback signal and a signal from the dimming sense and control circuit. 
     
     
         8 . The power supply of  claim 1 , further comprising at least one transistor connected between the primary winding of the transformer and the power input, a transformer driver connected to the at least one transistor, and a rectifier connected between the power input and the at least one transistor. 
     
     
         9 . The power supply of  claim 8 , wherein the at least one transistor comprises at least two transistors connected in a push-pull configuration across the primary winding. 
     
     
         10 . The power supply of  claim 9 , wherein the transformer driver is operable to generate a pulse train to drive the primary winding. 
     
     
         11 . The power supply of  claim 1 , further comprising a high/low driver connected between the secondary winding and the power output. 
     
     
         12 . The power supply of  claim 1 , further comprising a voltage level feedback signal connected to the gate drive, operable to measure a voltage across the primary winding. 
     
     
         13 . The power supply of  claim 1 , wherein the power output comprises an alternating current at a higher frequency than at the power input. 
     
     
         14 . The power supply of  claim 1 , wherein the power output comprises an alternating current sine wave. 
     
     
         15 . The power supply of  claim 1 , further comprising a rectifier connected between the secondary winding and the power output, wherein the power output comprises half sine wave pulses. 
     
     
         16 . A method of supplying power, the method comprising:
 rectifying a power input to yield a rectified power input;   generating a pulse train from the rectified power input;   driving a primary winding of a transformer with the pulse train;   driving a power output from a secondary winding of the transformer with an alternating current at a higher frequency than a frequency of the power input; and   switching the rectified power input based on a measurement at the power output.   
     
     
         17 . The method of  claim 16 , further comprising switching the rectified power input to set a dimming level at the power output. 
     
     
         18 . The method of  claim 17 , further comprising switching the rectified power input to set a dimming level based on a wired external dimming control signal. 
     
     
         19 . The method of  claim 17 , further comprising switching the rectified power input to set a dimming level based on a wireless external dimming control signal. 
     
     
         20 . The method of  claim 17 , further comprising switching the rectified power input to set a dimming level based on a power level at the power input as controlled by a triac-based dimmer.