Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2000-08-23
2001-10-09
Riley, Shawn (Department: 2838)
Communications: electrical
Condition responsive indicating system
Specific condition
C315S130000, C315S189000, C315S256000, C323S262000
Reexamination Certificate
active
06300878
ABSTRACT:
TECHNICAL FIELD
This invention relates to a constant current regulator using insulated gate bipolar transistor control.
BACKGROUND
Existing airport lighting systems employ a constant current regulator (CCR) that supplies power to a series of lights (or loads) used for airplane approach, touch-down, and taxi-way guidance. Because the intensity of a light is dependent upon a current through the circuit, the CCR regulates the current through the lighting system to control light intensity.
SUMMARY
The invention provides a constant current regulator that receives an AC input current from a source and provides a constant AC current to a load. To this end, the regulator includes first, second, third and fourth electronically controllable switches, a transformer coupled to the switches, and a controller connected to the switches. An output of the first switch is electrically connected to an input of the second switch and one input of the transformer primary winding. Additionally, an output of the third switch is electrically connected to an input of the fourth switch and another input of the transformer primary winding.
The controller is programmed to provide trigger signals to the switches, and to adjust the duty cycle of the trigger signals based on a comparison between an actual current value and a reference current value to provide a constant AC current to the load.
Embodiments may include one or more of the following features. For example, a trigger signal to a switch may be based on a pulse width modulated signal and delayed pulse width modulated signal, and a polarity of an AC input voltage. The switches may be arranged such that the AC input current is supplied to the primary winding of the transformer when the trigger signal to the first switch is on and when the trigger signal to the third switch is on, and the AC input current is isolated from the primary winding of the transformer when the trigger signal to the second switch is on and when the trigger signal to the fourth switch is on.
The electronically controllable switches may be insulated gate bipolar transistors (IGBTs), each IGBT having an emitter input and a collector input.
The regulator may further include, for each electronically controllable switch, a diode in an anti-parallel direction across the output and the input of the switch. The inputs of the first and third switches may be connected to the AC input. The outputs of the second and fourth switches may be electrically connected to each other.
The regulator may include first capacitor across the input of the first switch and the output of the second switch, and a second capacitor across the input of the third switch and the output of the fourth switch.
There may always be at least one switch conducting. For example, the first and fourth switches may be reciprocally and cyclically operated so that one of the first and fourth switches is conducting while the other of the first and fourth switches is non-conducting. Moreover, the second and third switches may be reciprocally and cyclically operated so that one of the second and third switches is conducting while the other of the second and third switches is non-conducting.
The controller may adjust the duty cycle of the trigger signal by adjusting a conversion ratio between a source voltage and a load voltage. Likewise, the controller may adjust the duty cycle of the trigger signal by adjusting a conversion ratio between a source current and a load current.
The load may include one or more lamps in series. The regulator may supply a constant current to each lamp such that the lamps have uniform brightness. Furthermore, the reference current value may be based on a selected brightness level for the lamps.
Output of the transformer may be fed back to the controller. Based on the feedback, the controller may compensate for changes in the conditions in the load to maintain constant current regulation.
The controller may be programmed to open a protection switch connected to the AC input and to stop providing a trigger signal to the first, second, third, and fourth switches upon detection of a fault in the AC line. A control panel may be connected to the controller.
The controller may sense the polarity of the input voltage and current to determine which switches are to be turned on in conjunction with the trigger signal. In this case, there may always be at least one switch conducting.
The regulator may also include input filtering that is provided by reactance of the AC source in conjunction with an input capacitor. The regulator may include output filtering that is provided by leakage reactance of the transformer in conjunction with an output capacitor. The regulator may include a safety resistor connected in parallel with the input capacitor to safely discharge when AC input current is removed from the regulator.
The regulator may be used in an airport lighting system to provide a constant current to each lamp in a series lamp circuit so that lamps have uniform brightness. A connected control panel may permit an air traffic controller to adjust the regulator to control the brightness of the lamps.
A feedback transformer may be coupled to a secondary winding of the transformer to provide a feedback signal to the controller. The actual output current may be based on the current value from the feedback transformer.
Other features and advantages will be apparent from the following description, including the drawings, and from the claims.
REFERENCES:
patent: 4295079 (1981-10-01), Otsuka et al.
patent: 4396868 (1983-08-01), Wantanabe
patent: 4675574 (1987-06-01), Delflache
patent: 5034659 (1991-07-01), Taniguchi
patent: 5283726 (1994-02-01), Wilkerson
patent: 5319534 (1994-06-01), Brennen
patent: 5319535 (1994-06-01), Brennen
patent: 5349517 (1994-09-01), Brennen
patent: 5355025 (1994-10-01), Moran et al.
patent: 5355295 (1994-10-01), Brennen
patent: 5359275 (1994-10-01), Edwards
patent: 5483148 (1996-01-01), Torrey
patent: 5521487 (1996-05-01), Liu
patent: 5526252 (1996-06-01), Erdman
patent: 5545971 (1996-08-01), Gomez et al.
patent: 5747972 (1998-05-01), Baretich et al.
patent: 5751138 (1998-05-01), Venkata et al.
patent: 5771161 (1998-06-01), Jackson et al.
patent: 6020726 (2000-02-01), James
patent: 0 264 135 (1988-04-01), None
patent: 2 320 967 (1998-07-01), None
patent: WO 99/08489 (1999-02-01), None
Patent Abstracts of Japan, 1 page, 11184541, Jul. 1999.
Galloway James H.
Giardini Douglas M.
Cooper Industries Inc.
Fish & Richardson PC
Riley Shawn
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