Patent Application
20130127372
The present disclosure is related to power supplies for supplying power to a lamp in a weathering apparatus. The weathering device is used to simulate prolonged exposure to environmental elements. One such environmental element is sunlight. In order to accurately simulate exposure to sunlight, a weathering apparatus may use a high intensity lamp such as a xenon lamp. The present disclosure is related to a device to supply a xenon lamp with an irradiance spectrum shaped high-frequency sinusoidal current at minimum loss in order to control a radiated spectrum from such lamp and to using waveform shaping to manipulate the switching mode output voltage and current for obtaining a controllable xenon lamp radiated spectrum. As a result, the xenon lamp radiation spectrum is more precisely controlled during weathering tests in order to better simulate solar radiation, as well as improve xenon lamp output in the ultraviolet part of the radiated spectrum and reduce unwanted radiation in the infrared part of the spectrum. The system of the present disclosure further includes an ignition assisting reservoir of energy provided during pre-ignition phase of the lamp such that the lamp requires a less powerful igniter.
Conventional weathering apparatus and methods do not control any radiated spectrum or provide any mechanism for control of the xenon lamp radiated spectrum in the manner and method disclosed herein, and as a result are not as accurate. Additionally, existing xenon lamp power supply technology is based solely upon providing line frequency power ballasting, which is bulky, heavy, requires many features to provide limited control, and has no functionality to provide for electronic, universal power factor correction.
One known conventional device uses a pulsed DC mode of the xenon lamp operation, which is merely a modulation of the duty-cycle. Such a device is disadvantageous because it generates very high current abrupt surges that can destroy the cathode and reduce the life of the xenon lamp. Additionally, this conventional method does not accurately simulate the sun daily cycle.
In general, arc lighting AC output electronic power supplies for high intensity discharge lamps only regulated the current and/or power to the lamp. Additionally, limited lamp dimming was provided by allowing for control to reduce the magnitude of the lamp current. Typically, they were three stage power supplies consisting of a power factor corrector, a buck converter, and a low frequency AC inverter. They also required a separate igniter whose power was comparable to the whole power supply rated power to start the lamp. Irradiance control was non-existent, so as to not be considered.
Therefore, for devices that utilize gas discharge lamps and for devices that require the simulation of sunlight or some other irradiance spectrum, there exists a need for improved power supplies. Such needs include the ability to control the irradiance spectrum of the lamp to more accurately simulate the sun's daily cycle for use in devices such as accelerated weathering devices.
In addition, devices that utilize gas discharge lamps with known power supplies, require systems that can deliver a significant pulse of energy during ignition of the lamp. Also, the current control mechanisms of known power supplies can result in abrupt surges or spikes in current that can negatively impact the reliability and life of the gas discharge lamp. Therefore, improved power supplies are needed to provide ignition systems with lower power requirements such that operating costs of the device are reduced and the flexibility for choice of igniters is improved.
Generally, one aspect of the present disclosure may include an accelerated weathering apparatus that may include a power supply that can control both the xenon lamp radiated spectrum and its intensity in order to fully simulate the sun's daily cycle, improve the ultraviolet output, and reduce the infrared radiation. In one embodiment, a power supply may include a high frequency inverter for obtaining a controllable, waveform defined, output power being supplied to a xenon lamp. This provides the ability to develop a spectrum shaped lamp irradiance, a resonant circuit as a current source for a direct xenon lamp supply, and at the same time, a high-power, high voltage, xenon lamp backup for reliable arc initiation and setting at lower ignition voltage with a less powerful igniter. As a result, the embodiment may be more compact and less expensive due to use of high frequency power conversion technology and waveform manipulation, as well as have an ability to be computer monitored and controlled locally and/or remotely, even via the internet.
Another aspect of the present disclosure may include an accelerated weathering device that may include using a near resonant high frequency switching to create a lamp pre-ignition condition that can be advantageously configured to assist in lamp ignition. The size and energy requirements of known igniters may be reduced using aspects of the present disclosure as well as using other previously considered impractical methods of lamp ignition due to the back-up of high voltage and stored energy of some embodiments. The present disclosure allows for increased flexibility when choosing ignition type with potential for lower costs and increased operating life.
In another aspect of the present disclosure, a power supply is provided that includes a spectrum shaping component that is capable of providing a signal that controls the irradiance spectrum of a lamp.
In another aspect of the present disclosure, a power supply is provided that includes a pre-conditioning component that supplies a lamp with a high voltage and a reservoir of back-up energy to assist in the ignition and operation of the lamp.
In yet another aspect of the present disclosure, a weathering device is provided that includes a power supply that is able to control the irradiance spectrum of a lamp such that it simulates the sun's daily cycle.
The following disclosure as a whole may be best understood by reference to the provided detailed description when read in conjunction with the accompanying drawings, drawing description, abstract, background, field of the disclosure, and associated headings. Identical reference numerals when found on different figures identify the same elements or a functionally equivalent element. The elements listed in the abstract are not referenced but nevertheless refer by association to the elements of the detailed description and associated disclosure.
The present disclosure is not limited to the particular details of the apparatus depicted, and other modifications and applications may be contemplated. Further changes may be made in the apparatus, device or methods without departing from the true spirit of the scope of the disclosure herein involved. It is intended, therefore, that the subject matter in this disclosure should be interpreted as illustrative, not in a limiting sense.
In one embodiment of the present disclosure, a weathering device is provided that includes a system for generating simulated sunlight as shown in
Lamp (10), in this example, is a xenon lamp. However, other gas discharge lamps can be used with the present disclosure including the embodiments of power supply (86) described herein. A xenon lamp is useful in the presently disclosed context for a xenon lamp's ability to simulate sunlight. Other lamps, however, may be used with the teachings of the present disclosure regarding the ignition of and irradiance spectrum shaping of other gas discharge lamps.
In the embodiment as shown in
The phase-shifted full bridge inverter (2) receives power from the power factor corrector (1) and signal control from the feedback control circuit (6). It delivers power to the main transformer (3) via primary winding (4). The primary winding (4) of main transformer (3) loads the phase-shifted full-bridge inverter (2). A main secondary winding (8) transfers power to the series resonant circuit (9). An additional secondary winding (5) is a voltage feedback signal source to the feedback control circuit (6) to sense the status of power being transferred through the main transformer (3) and provide for necessary control.
The feedback control circuit (6) signals the phase-shifted full-bridge inverter (2), providing the necessary information for output control and regulation of the full system output power. The feedback control circuit (6) is also signaled by the spectrum shaping circuit (7). The feedback control circuit (6) senses voltage via the main transformer (3) secondary winding (5) and current sense circuit (17). The spectrum shaping circuit (7) signals a specific waveform construction to the feedback control circuit (6), and, it allows for user input control of the feedback loop current by providing for selection of, and where required, additional output spectrum shaping can occur.
The series resonant circuit (9) transfers power to the xenon lamp (10) during normal operation and provides current stabilization. It also initiates energy support for the pulse igniter (16) through the igniter transformer secondary windings (14) and (15) by creating a base voltage across the xenon lamp (10) to help start the lamp and provide sustaining energy once an ignition arc is established. Series resonant circuit (9) couples to xenon lamp (10) through igniter transformer (11), secondary windings (14) and (15) and current sense circuit (17). The primary windings (12) and (13) of igniter transformer (11) are driven by the pulse igniter (16), which is signaled by the unloaded series resonant circuit (9) during the pre-ignition and ignition phases of lamp start-up. The pulse igniter (16) pulses the igniter transformer (11) primary windings (12) and (13) to create a high enough voltage on the igniter transformer (11) secondary windings (14) and (15) to ignite the lamp by inducing an alternating current arc to flow between lamp cathodes. The pulse igniter (16) is fed from the power factor corrector (1) output for the best stability. Secondary windings (14) and (15) may be wound such that the starting points do not impose additional impedance on lamp (10) current development but produce high differential voltage across lamp (1) when pulse igniter (16) starts.
Current sense circuit (17) is a circuit configured to supply a feedback signal to feedback control circuit (6) that indicates the state of lamp (10) such that the power supply can manage or correct the power output through phase-shifted full bridge inverter (2). Current sense circuit (17) as shown in
In another embodiment, as shown in
The modulation of current in power supply (86) can be accomplished via various methods to accomplish the irradiance spectrum shaping of the present disclosure. One embodiment of the power supply output control is shown in
In another aspect of the present disclosure, the power supply includes an ignition system with ignition assistance and an igniter element. As shown in
In operation of one embodiment of the present disclosure as shown in
At ignition, the arc in the xenon lamp (10) establishes itself by means of a high voltage pulse from the pulse igniter (16) coupled through the igniter transformer (11) to the xenon lamp (10). Once an arc occurs, the lamp impedance is abruptly reduced and there is no longer a need for an ignition pulse from the pulse igniter (16). The xenon lamp (10) now shunts the energy of the series resonant circuit (9) through the igniter transformer (11) secondary windings (14) and (15) sustaining the ignition arc, reducing output voltage to that normally required for the lamp, and setting up constant lamp current.
The main factors in the determination of current magnitude through the xenon lamp (10) are the output voltage and frequency delivered by the secondary winding (8) of the main transformer (3), the inductor and capacitor elements, (not shown, but known to one of ordinary skill in the art) that determine the tuned frequency of the series resonant circuit (9), and inductance value of the inductor element in the series resonant circuit (9).
The spectrum shaping circuit (7) may be used to adjust irradiance spectrum of the xenon lamp (10) as determined by setting selection via user input. This is performed by using a waveform generator within spectrum shaping circuit (7) to act upon the feedback signaling through the feedback control circuit (6) and adjust or shape the xenon lamp (10) output current envelope. The lamp irradiance spectrum control is now governed by controlling the shape of the overall current envelope flowing through the xenon lamp (10). Therefore, by changing or trimming the shape of the signal waveform generated in the spectrum shaping circuit (7) one can adjust the xenon lamp (10) irradiance spectrum to a desired one or within a desired range. The irradiance spectrum variation during this adjustment can be monitored and verified by means of a spectroradiometer or spectrum analyzer of appropriate range.
Other embodiments of the power supply of the present disclosure include alternative configurations of the ignition system and ignition assistance and igniter element. In one example, shown in
In another embodiment of the power supply of the present disclosure, shown in
In still another embodiment of the power supply of the present disclosure, shown in
The reservoir of back-up energy provided by the power supply during pre-ignition is depicted in the image of
The preceding detailed description is merely some examples and embodiments of the present disclosure and that numerous changes to the disclosed embodiments can be made in accordance with the disclosure herein without departing from its spirit or scope. The preceding description, therefore, is not meant to limit the scope of the disclosure but to provide sufficient disclosure to one of ordinary skill in the art to practice the invention without undue burden.
This application is a non-provisional application that claims the benefit of and priority to U.S. Provisional Application No. 61/561,157 filed Nov. 17, 2011 and is hereby fully incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61561157 | Nov 2011 | US |
