Abstract:
A string of LED loads is supplied by means of a rectified mains voltage. A cathode of each LED load is coupled to ground by means of a string. The strings are made conductive and non-conductive one by one in dependency of the instantaneous value of the rectified mains using both voltage and current sensing.
Abstract:
A lighting driver includes a rectifier having an input connected to receive AC electrical power from an electronic ballast and having an output connected to supply a current to a plurality of light emitting diodes (LEDs) arranged in series with each other in a string, and a switching device disposed at the output of the rectifier and configured to receive a switching control signal and in response thereto to execute a switching operation to modulate an amount of power supplied to the plurality of LEDs so as to cause an average of the power supplied to the plurality of LEDs to be equal to a target power level. A current sensor may be provided to sense the current, and a controller configured to control the switching operation of the switching device in response to the sensed current.
Abstract:
A series arrangement of LED loads (LP1-LP4) is coupled between output terminals of a rectifier having its input terminals coupled to a mains supply supplying a low frequency AC voltage. Control means render the LED loads conductive one by one, when the amplitude of the supply voltage increases, and non-conductive one by one when the amplitude of the supply voltage decreases. The first LED load (LP1, LP2) has a forward voltage that is substantially higher than that of the other LED loads. As a consequence, the LED utilization is comparatively high, thus allowing the LED loads used in the series arrangement to be comparatively cheap.
Abstract:
Driver device and a corresponding driving method for driving a load, in particular an LED assembly comprising one or more LEDs. To provide a better performance, better cost-efficiency, improved power factor and reduced losses, a driver device (1,1′, 2, 2′) is provided comprising a rectifier unit (10) for rectifying a received AC supply voltage (VS), load terminals (20) for providing a drive voltage (VL) and/or a drive current (IL) for driving said load, a capacitive storage unit (30) coupled between said rectifier unit and said load terminals for storing electrical energy provided by said rectifier unit and providing electrical energy to said load, and a bridge switching unit (40) coupled between said rectifier unit and said load for switching said capacitive storage unit into a load current path from said rectifier unit to said load terminals with a desired polarity and for switching said capacitive storage unit out of said load current path.
Abstract:
Driver device and a corresponding driving method for driving a load, in particular an LED assembly comprising one or more LEDs. To provide a better performance, better cost-efficiency, improved power factor and reduced losses, a driver device (1,1′, 2, 2′) is provided comprising a rectifier unit (10) for rectifying a received AC supply voltage (VS), load terminals (20) for providing a drive voltage (VL) and/or a drive current (IL) for driving said load, a capacitive storage unit (30) coupled between said rectifier unit and said load terminals for storing electrical energy provided by said rectifier unit and providing electrical energy to said load, and a bridge switching unit (40) coupled between said rectifier unit and said load for switching said capacitive storage unit into a load current path from said rectifier unit to said load terminals with a desired polarity and for switching said capacitive storage unit out of said load current path.
Abstract:
The present invention relates to an LED lamp (1) adapted for operation with an alternating current. The LED retrofit lamp (1) comprises a LED unit (7, 7′, 7″, 7′″) and a compensation circuit with a controllable switching device (9, 9′), connected parallel to said LED unit (7, 7′, 7″, 7′″) to provide an alternate current path. A control unit (10, 10′, 10″) is adapted to control said switching device (9, 9′) in a compensation mode in which said switching device (9, 9′) is set to the conducting state for the duration of a shunt period in each half cycle of the alternating current to allow adapting the power/current of the inventive LED lamp (1), so that a versatile and optimized operation of the lamp (1) is possible.
Abstract:
LED light source comprising a string of LED loads (LED1-LED4) supplied by a rectified mains voltage. The number of LED loads carrying current is increased as the momentary amplitude of the rectified mains voltage increases, and is decreased as the momentary amplitude of the rectified mains voltage decreases. The order in which the LED loads start carrying a current and the order in which the LED loads stop carrying a current is reversed for each half period of the mains.
Abstract:
A lighting driver includes a rectifier having an input connected to receive AC electrical power from an electronic ballast and having an output connected to supply a current to a plurality of light emitting diodes (LEDs) arranged in series with each other in a string, and a switching device disposed at the output of the rectifier and configured to receive a switching control signal and in response thereto to execute a switching operation to modulate an amount of power supplied to the plurality of LEDs so as to cause an average of the power supplied to the plurality of LEDs to be equal to a target power level. A current sensor may be provided to sense the current, and a controller configured to control the switching operation of the switching device in response to the sensed current.
Abstract:
A LED light source comprises a first rectifier (DB1) having input terminals coupled to an AC voltage source and output terminals connected by a first series arrangement comprising N LED loads and further comprises circuitry (I1, I2, I3, CC) for making the LED loads one by one carry a current when the momentary value of the AC voltage increases and one by one stop carrying a current when the momentary value of the AC voltage decreases. The LED light source also comprises a second rectifier (DB2) having input terminals coupled to the AC voltage source via a reactive element and LED1 LED2 LED3 output terminals connected by a second series arrangement comprising M LED loads and further comprises circuitry (I4) for making the LED loads one by one carry a current when the momentary value of the AC voltage present at the input terminals of the second rectifier increases and one by one stop carrying a current when the momentary value of the AC voltage decreases.
Abstract:
An interface circuit is disclosed for operating a light source from an electronic fluorescent driver. In one example, the interface circuit comprises input terminals for connection to lamp connection terminals of the electronic fluorescent lamp driver, a first string interconnecting a first pair of input terminals, a second string interconnecting a second pair of input terminals, a third string interconnecting a first terminal of the first string and a second terminal of the second string and comprising a rectifier, output terminals of said rectifier being coupled during operation to the light source. When a light source is operated making use of the interface circuit, a proper emulation of a fluorescent lamp is obtained.