摘要:
A power line communication system transmits a dimming level to an electronic ballast to regulate the power consumed by a lamp. The power line controller has a notch generation circuit that generates notches on an AC power signal with a time duration in accordance with the dimming level of the lamp. A dimming interface associated with the electronic ballast detects the notches on the AC power signal. The dimming interface generates a ballast dimming level signal with a signal level related to the time duration of these notches.
摘要:
A circuit for preheating filaments in lamps powered by an electronic ballast includes an inverter tank circuit and a preheat tank circuit. The preheat tank circuit has a preheat capacitor connected in parallel with a primary winding of a filament preheat transformer. A cut-back capacitor is connected between the preheat tank circuit and circuit ground. The filament preheat transformer has secondary windings coupled to the first and second lamp terminals to provide a filament preheat voltage. The inverter operates at a preheat frequency during a lamp preheat mode and at a steady-state frequency during a lamp steady-state mode, the steady-state frequency being lower than the preheat frequency. The preheat tank circuit has a natural resonant frequency that is approximately the same as the preheat frequency so that when the ballast is operating in the steady state mode, the filament voltage is substantially lower than when the ballast is operating in the preheat mode.
摘要:
A ballast circuit includes a filament cutback circuit to reduce a pre-heat voltage after the lamp filaments have been pre-heated. The filament cutback circuit includes a filament cut-back inductive component magnetically coupled to the resonant inductive component in the inverter to receive a filament cutback control voltage associated with an AC voltage for powering the lamps. During the pre-heating period, the filament cutback control voltage is not high enough to charge a chargeable component to a switch threshold level. However, during lamp ignition, the filament cutback control voltage is increased and charges the chargeable component to the switch threshold level. This causes a switch device to operate in a conductive switch state and the filament cutback circuit suppresses the pre-heat voltage.
摘要:
A method and system for reducing and/or eliminating striations from gas discharge lamps powered by an electronic ballast charges a capacitive energy device, which is coupled in parallel with the lamp, when the capacitive energy device detects that a predetermined lamp voltage condition has been satisfied. The system/method supplements the current supplied to the lamp by the electronic ballast with current supplied from the capacitive energy device when the predetermined lamp voltage condition is not satisfied. The supplemental current supplied to the lamp creates a harmonic-rich lamp current waveform that reduces and/or eliminates striations.
摘要:
A power line communication system communicates a ballast dimming level to an electronic ballast over an AC power line. A power line controller is operable to generate the ballast control signal and to insert that signal on the AC power signal being transmitted over the AC power line. A power line receiver receives the AC power signal and extracts the ballast control signal from the AC power signal to generate the dimming level signal corresponding with the desired ballast dimming level. To insert the ballast control signal on the AC power signal, the power line controller has a transformer coupled to the signal pattern circuit. The secondary winding of this transformer is connected in series with the AC power line to insert the ballast control signal on the AC power signal. This AC power signal is then transmitted to the electronic ballast. To extract the ballast control signal out of the AC power signal, the power line receiver has a resonant circuit connected in series with the AC power line. The resonant circuit should be tuned to transmit the ballast control signal and to filter out the AC power signal. A dimming level sensing circuit then senses the signal pattern on the ballast control signal and generates a dimming level signal corresponding to the desired ballast dimming level.
摘要:
An arc protection circuit is provided for a current-fed, parallel-resonant inverter ballast. The circuit includes a lamp current rate of change sensing circuit coupled with one or more lamps to detect a total lamp current; a ballast shutdown circuit to disable the ballast in response to a disturbance in the detected signal; a startup delay circuit, at least a portion of which defines a first time delay from a predetermined condition during which the ballast can not be disabled by the shutdown circuit; and an automatic restart circuit to enable restarting of the ballast, at least a portion of which defines a second time delay during which the ballast remains disabled, after which the ballast is restarted.
摘要:
A modular electronic ballast is provided for powering a fluorescent lamp. A motherboard is configured to receive an AC input signal, one or more supplemental input signals and a feedback signal from the lamp. A ballast control circuit generates an output signal for an oscillating inverter driving the lamps. A daughter card is coupled to the motherboard and selected from a plurality of daughter cards, each configured to provide a dimming control signal having predetermined characteristics and readable by the control circuit. The daughter cards are collectively configured to provide dimming control signals in response to each of a line-coupled demand response interface, one or more digitally addressable interfaces, analog dimming signals received via said supplemental communications bus, and three-wire phase control signals received via said AC line and said supplemental communications bus. The motherboard is configured to interchangeably receive any one of the daughter cards. The ballast control circuit is effective to generate output signals in response to the feedback signal, dimming control signal and a predetermined lamp output value.
摘要:
An electronic ballast uses a voltage sampling circuit and a voltage control circuit to limit the open circuit voltage of the ballast. A lamp voltage sensing circuit is provided that uses a voltage dividing capacitor to accomplish lossless monitoring of the open circuit voltage of the ballast. A resistor placed in series with the sampling capacitor is used to create a voltage that turns a control transistor off and on. The control transistor produces a gating signal trimming signal that a half bridge driver uses to alter the gating signals provided to the inverter transistors of the ballast. A cable compensation circuit is included that minimizes variations in the open circuit voltage due to the connecting and disconnecting of a cable to the ballast by turning the control transistor off and on.
摘要:
An improved high input voltage instant start electronic ballast uses a substantially lossless snubber circuit. The substantially lossless snubber circuit is incorporated into the ballast to reduce turn off losses and increase the efficiency of the ballast. The snubber circuit includes two capacitors connected in parallel with respect to the two switching transistors or FETS in the inverter of the ballast. A series-resonant lamp voltage sensing circuit is also provided that uses a voltage dividing capacitor to accomplish lossless monitoring of the open circuit voltage of the ballast. A cable compensation circuit minimizes variations in the open circuit voltage due to the connecting and disconnecting of a cable to the ballast by limiting the turn on times of the transistors during high voltage conditions.
摘要:
A magnetic device is provided for placement on the top surface of a printed circuit board with surface mount connection on the bottom surface. The circuit board includes first and second sets of slots bisecting each other. The device includes a bobbin with a plurality of support members each having a face shaped to engage the top surface of the printed circuit board and a plurality of pins attached to the support members. The pins have a first portion shaped to pass through the first set of slots, and a second portion shaped to pass through the second set of slots. The second portion of the pins is shaped to engage the bottom surface of the circuit board, locking the magnetic device in place against the top surface of the circuit board and providing a soldering area for surface mounting on the bottom surface.