| 20100118577 | SINE WAVE LAMP CONTROLLER WITH ACTIVE SWITCH COMMUTATION AND ANTI-FLICKER CORRECTION - A pulse width modulated half bridge dimming controller for dimming a lighting ballast is described. The top half of the bridge is comprised of two switches, the top switch set, and the bottom half of the bridge is comprised of two switches, the bottom switch set. Each switch also has a diode in parallel with it. The drivers for the switches are configured so that each of the switches can be turned on and off independently of all of all the other switches. Preferably, the controller is capable of operating in all four quadrants. In one preferred embodiment the switches are IGBTs. The switches are controlled in a manner so that when one of the switch sets changes states, the second switch set has one switch on and one switch off, so that one of the diodes in the second switch set is disposed to block shoot through and provide a path to allow current to continue flowing in the inductive load. | 05-13-2010 |
