DRIVER CIRCUIT BETWEEN FLUORESCENT BALLAST AND LED

摘要

Driver circuits (1) for driving loads (2) comprising light emitting diodes are provided with rectifiers (11-14) for exchanging first current signals with fluorescent ballasts (3) such as active electronic ballasts and for supplying second current signals to the loads (2), with switch circuits (21-27) coupled to or forming part of the rectifiers (11-14) for controlling amounts of power supplied to the loads (2), and with controllers (31) for controlling the switch circuits (21-27) such that switching frequencies of the switch circuits (21-27) are equal to or lower than twice the frequencies of the first current signals. Detuning circuits (4) match output impedances of the fluorescent ballasts (3) and input impedances of the rectifiers (11-14). Start-up circuits (5) increase impedances at input terminals of the rectifiers (11-14) at start-up. Current sensors (6) and voltage sensors (7) provide feedback. The controllers (31) synchronize the switching frequencies of the switch circuits (21-27) and switching frequencies of the active electronic ballasts. Detectors (8) detect zero crossings in the first current signals.

主权项

1. A driver circuit for driving a load, the load comprising at least one light emitting diode, the driver circuit comprising
a rectifier for exchanging a first current signal with a fluorescent ballast and for supplying a second current signal to the load, a switch circuit coupled to or forming part of the rectifier configured to control an amount of power supplied to the load, and a controller configured to control the switch circuit, a switching frequency of the switch circuit being equal to or lower than twice a frequency of the first current signal, the fluorescent ballast comprising an active electronic ballast, the controller configured to synchronize the switching frequency of the switch circuit and a switching frequency of the active electronic ballast that is equal to the frequency of the first current signal.