MXPA98009582A - Universal high intensity discharge (hid) electronic starter - Google Patents

Abstract

An electronic starter (60) for high intensity discharge devices (80). The present invention includes a voltage controlled oscillator with a resonant frequency that is determined by the direct voltage applied thereto and by a still further resonant circuit (62, 64) that includes the high intensity device (80) as part of this still further resonant circuit (62, 64).

Description

UNIVERSAL ELECTRONIC PRIMER OF HIGH INTENSITY DISCHARGE TECHNICAL FIELD The present invention relates to an electronic primer for high intensity discharge lamps and all devices with similar characteristics.

PREVIOUS TECHNIQUE Several devices have been designed in the past to prime or start and operate high-pressure sodium lamps and other high-intensity discharge devices. However, most of them have used public electric power networks of 50/60 hertz that require relatively large and heavy inductors or ballasts. Also, many of them have involved the relatively high current switching that contributes to the deterioration of the lamp units and the associated circuitry, shortening life and also generating undesirable harmonics that could interfere with other electronic devices. One of these devices is described in United States Patent No. 3,889,152 issued to Bodine, Jr. and Rosiak, in 1975, entitled "Priming and Operation of Ballasts for High Pressure Sodium Lamps". This device involves the activation of a control rectifier when the capacitor voltage reaches a predetermined level. This approach has the above mentioned problems. The closest reference known to the Applicant corresponds to the application notes AN-973 published by International Rectifier, 233 Kansas Street, El Segundo, CA90245, where an application of the manufacturer's MOSFET transistors is explained (under the trade name HEXFET), the way it is applied to high intensity discharge lamps and fluorescent lamps. Another reference corresponds to United States Patent No. 5,130,611 issued to Johns, in 1992, entitled "Universal Electronic Ballast System". As with the previous reference, this invention uses a switching or interrupting device which has, at high current intensities, adverse results as those mentioned above. None of these references or other devices of the prior art use a device that ionizes the vapor in the charge of the high intensity discharge device with a high frequency electric field in the range of 300 kilohertz and after the ionization, the frequency is reduces by the contribution of the device impedance to the entire resonance circuit and maintains an operating frequency between 20 and 100 kilohertz. By not maintaining stable operating frequency, as shown by the manufacturer and others mentioned above, harmonics and undesirable distortions are minimized. Other patents that describe the closest matter provide other more or less complicated features that fail to solve the problem in an efficient and economical way. None of these patents suggests the novel features of the present invention.

SUMMARY OF THE INVENTION One of the main objects of this invention is to provide an electronic primer device that can be used with high intensity discharge devices, among which lamps of this type are included, which decreases the required start time. Another object of the invention is to provide a device that saves electrical energy while maintaining the same luminous intensity in high intensity lamp devices. Still another object of the present invention is to provide a device that includes an oscillator to supply the start or prime electric frequency at a frequency of 300 kilohertz and at variable operating frequencies ranging from 20 and 100 kilohertz, to the frequency of the line of AC input (50-60 hertz). Still another object of the invention is to provide a device that keeps harmonics and undesirable distortions at a minimum. Another object of the invention is to provide an electronic primer device for high intensity discharge devices that is efficient in volumetric sense and of relatively light weight. Another object of the invention is to provide an electronic primer that generates a minimum of pulses and other undesirable harmonics. Still another object of the invention is to provide an electronic primer device that maximizes the power factor, approaching 1.0 and avoiding the need to compensate the capacitors, as is typically required when using conventional ballasts. Another object of this invention is to provide an electronic primer device that generates a minimum of heat regardless of the high frequencies at which it operates. Other objects of the invention will arise from the following section of the specification wherein the detailed description has the purpose of revealing the invention in the most complete way, without placing limitations on it.

BRIEF DESCRIPTION OF THE DRAWINGS Taking into account the above and other related objects, the invention consists of the details of construction and combination of parts that will be more fully understood with the following description, when taken in conjunction with the accompanying drawings, in where: Figure 1 represents a simplified block diagram of the invention. Figure 2A illustrates a diagram that provides a graphical representation of the behavior of current intensity over time, in a high intensity discharge lamp, operating over time, using a conventional ballast B and one with the present invention A. Figure 2B shows the waveforms of the input voltage V of the public network and current I, substantially in phase, when the present invention is used. Figure 3 provides a schematic diagram of one of the preferred embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED MODE With reference to Figure 1, wherein the present invention in general refers to the number 10, it can be seen that it basically includes a rectifier circuitry 20, oscillator circuitry 40, resonant ballast circuit 60 and load 80 of high intensity discharge. For the purposes of this application, we will specifically refer to high intensity discharge lamps for load 80, but there are other types of high intensity devices besides lamps, where the benefits of the present invention may be utilized. Circuit protection circuitry 100 disables oscillator circuitry 60 when load 80 is removed or when other abnormal conditions exist. Figure 1 is a general block diagram and shows a simplified version of the present invention. A rectified and variable direct current source of 300 V.C.D. It is obtained from the public network of 220 V.C.A. The variable voltage C.D. Oscillator circuitry 40 is applied for which its resonance frequency is a function of voltage C.D. applied variable and defines the nominal values of the component of the resonance circuitry 60. To achieve this voltage C.D. variable the capacitance of the capacitor 21 is selected so that, in the preferred embodiment, it is in the range of 7 microfarads, which is extremely small. In the application notes mentioned above, the selected capacitance was 100 microfarads, in other words, more than an order of magnitude higher. The notes follow the conventional norm of providing stable direct current output, which is contrary to what is pursued with the present invention. The lamp load 80 is connected in parallel with the capacitor 62 to apply the required ionization voltage and the inductor 64 acts as a current limiter. By providing a variable direct current voltage to a resonant ballast circuit 60, the oscillating frequency also varies according to a predetermined range. A single way of creating a variable direct current voltage source is, as described above, by selecting an excessively small filter capacitor. In the preferred embodiment, the oscillation determining components and the variable voltage are selected to provide an oscillating frequency ranging from 20 kilohertz to 100 kilohertz in 0.00833 seconds (1 / 2x60) for networks of 60 hertz C.A. As shown in Figures 4 and 4A, the conventional resonant ballast circuit, as well as that described in the notes of International Rectifier, presents 52/59 a reactive load at the entrance A.C. with a relatively low power factor and the harmonic is concentrated in the 40 KHz area. With the present invention, the oscillating frequency varies and the undesirable harmonics distributed over a wide band with considerably smaller intensity. The latter is more manageable and easier to eradicate or filter. Figure 1 shows a simplified form of the operation of the invention after initiation or priming. The initiation or priming circuitry is explained below. Basically, an oscillating current is passed through a resonant ballast circuitry 60 using the impedance of the inductor 64 to limit the current intensity in order to avoid a runaway situation. The switching circuits Sx and S2 cause the periodic charging of the capacitors 62 and 63. If there is no lamp load 80 connected, this periodic operation is performed at the resonance frequency which, in the preferred embodiment, is in the vicinity of 300. KHz. With the lamp load 80 in parallel (after ionization) with the capacitor 62, the resonance frequency is decreased after the initiation or priming ionization is achieved (before that lamp point load 80 essentially behaves as an open circuit) at an amount between 20 KHz and 100 KHz in the preferred embodiment, depending on the voltage applied by the rectifying unit 20. When the frequency decreases, the reactive impedance increases through 62. For maximum efficiency, the impedance Capacitor capacitor 62 at operating frequencies must approximate the load's operating impedance. The protection circuitry 100 includes switching circuit S3 which bypasses the gate to the switching circuit Sl r by disabling it, when the voltage induced in the secondary inductor 64 exceeds a predetermined amount. Otherwise, if the oscillator circuit 40 is left running indefinitely at the resonance frequency (when the lamp load 80 is removed) the circuit could burn out. This protection circuitry 100 is described in the IR notes referred to above. The operation of the invention, according to the scheme shown in Figure 3, is as follows. First, when the alternating current source is applied, it is rectified and left to undulate as described above. The capacitor 41 is charged through the resistor 42. The nominal data of these components in the preferred embodiment are 10 microfarads and 2 megaohms, respectively. The capacitor 41 is charged at approximately 32 volts in approximately 2 seconds. The DIAC 43 has a capacity 52/59 rated at 32 volts and is connected through a limiting resistor 43 '(not shown in the application notes) to the gate of transistor 44 through resistor 45, which has a resistance of 100 ohms. The transistor 44 is implemented with a MOSFET transistor, part No. IRF 740, or equivalent device manufactured by Harris and Motorola. When the voltage across the capacitor 41 exceeds 32 volts, the transistor 44 (also the MOSFET transistor IRF 740) is turned on by closing the circuit of the resonance circuit 60 through the primary transformer 46 'of the transformer 46. Simultaneously, the capacitor 41 is discharged through resistor 47, with a nominal capacity of 1 kiloohm, or approximately 20 times faster than the speed at which it was charged. The inductor 64 is designed so that, with the total capacitance of the capacitors 62 and 63 in series, it is in resonance at approximately 300 Mhz which is a transient start frequency. The implementation of the inductor 64, in the preferred embodiment, includes a primary coil 64 'having 35 windings with wire 12 and a secondary coil 64"having three windings with wire No. 30. The capacitor 62 is a 0.033 microfarad capacitor and the capacitance for capacitor 63 is 1.5 microfarads, which is considered greater Since the reactance of capacitor 62 is considerably larger than the reactance of capacitor 63, most of the voltage across these two capacitors will appear between the capacitor terminals 62, which in turn are connected in parallel with the lamp load 80. However, once the lamp load 80 initiates conduction, the voltage across the capacitor 62 lowers or decreases towards the nominal voltage of the load of the lamp 80 and the oscillatory and resonance frequency for the oscillator circuit 40 is decreased to between 20 Kilohertz (dictated by the effective series combination of capacitance resonance r 63 and inductor 64 and to a lesser degree, capacitor 62, which is basically off) and 100 kilohertz. At these lower operating frequencies and "Q", the inductor 64 restricts the current through the ionized lamp charge 80. These lower frequencies are then the operating frequencies that can be varied between approximately 20 KHz and 100 KHz, thus distributing the resulting harmonics. The coil 46 'of the transformer 46 has three windings with No. 22 wire and conducts current in one direction when the transistor 44 is turned on and the capacitors 62 and 63 are being charged. After reaching a full charge, the current ceases and the magnetic energy stored in the transformer 46 induces a voltage in the coil 46"(19 windings, wire No. 30) of 52/59 reverse polarity which causes the MOSFET transistor 48 (similar to transistor 44) to be conductive, providing a path to the discharge capacitors 62 and 63 through the primary coil 46 ', since the transistor 44 is now turned off. Once ionized, the frequency drops automatically since the capacitor 62 is practically in derivation and from that point the inductor reactance 64 is what practically limits the current through the lamp load 80. In this form, the lamp load 80 is supplied with the necessary energy at a high frequency without requiring the use of heavy ballasts. Even the notes of the previous reference application (Figure 11, page 6) show that two "E" cores are required to implement the transformer, while in the present invention an "E" core and a "I" core will suffice. This reduces the weight of the components which is especially desirable for those who are used in street lighting. As mentioned before, the protection circuitry 100 monitors the voltage across the primary coil 64 'of the inductor 64, as seen in Figure 3. The voltage induced in the secondary coil 64"is rectified with the diode 101 and used to charge the capacitor 102. A voltage of approximately 20 volts is present through the capacitor 102 under normal operation. 52/59 However, if this voltage exceeds a predetermined voltage, for which the nominal load of the DIAC 103 is selected (32 volts in the preferred mode), then the transistor 104 (similar to transistor 44) is turned on, closing the gate of transistor 44 and thereby incapacitating any other oscillation. A prolonged rise in voltage may occur when the lamp load 80 is removed or does not work according to its specifications. One of the advantages to operate at higher frequencies (higher than public networks 50-60 Hz) is that the size and weight of the inductive components are reduced. The foregoing description presents the best understanding of the objects and advantages of the present invention. Different modalities of the inventive concept of the invention can be effected. It should be understood that all the material presented here should be interpreted simply as illustrative and not in a limiting sense.

INDUSTRIAL APPLICABILITY It is evident from the previous paragraphs that an improvement of this type in an electronic primer is very desirable for the high intensity discharge devices that use them, including lamps of this type, which decreases the required start time. 52/59

Claims (2)

1. CLAIMS: 1. An electronic primer for a gas discharge lamp charge comprising: A) a source of electricity means for supplying a periodically variable direct voltage; B) a controlled voltage oscillator means selectively connected to the power source means and adapted to provide an initiating oscillating signal of approximately 300 kilohertz when connected to the power source means; C) means for providing a resonance frequency to the oscillating means, which includes a reactive inductance element in series with first and second capacitive reactive members, all in series, and the load is connected in parallel with the second reactive capacitor member , so that the resonant frequency of operation of the combination decreases when the load is ionized, where the operating resonance frequency varies periodically between 20 kilohertz and 100 kilohertz; D) a detector means for monitoring the voltage through the reactive inductance element; and E) a means for incapacitating the oscillating means connected to the detector means, so that the oscillating means becomes incapacitated when a voltage is detected. 52/59 default. The electronic primer according to claim 1, wherein the electrical source means for supplying direct voltage includes a complete bridge rectifier having an output. The electronic primer according to claim 2, wherein the electronic source means for supplying a variable forward voltage includes a capacitor element at the output, so that a non-wavy voltage waveform is supplied. The electronic primer according to claim 3, wherein the capacitance of the first reactive capacitor member is at least ten times greater than the capacitance of the second capacitor reactive member. The electronic primer according to claim 4, wherein the second capacitor reactive member has a capacitance range between 0.01 and 0.05 microfarads. The electronic primer according to claim 5, wherein the means for incapacitating the oscillating means includes a secondary inductor coil coupled to the inductance reactive element, such that a voltage induced in the secondary inductor coil is proportional to the current through the inductor. reactive element of inductance. 52/59 7. The electronic primer according to claim 6, wherein the oscillating means includes transistor switching circuitry. The electronic primer according to claim 7, wherein the oscillating means includes an RC circuit for initiating oscillation of the oscillator means at a predetermined frequency.
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