DE2160121A1 - Feed circuit arrangement for a load with variable resistance - Google Patents

Description

Feed circuit arrangement for a load with variable resistance

The invention relates to a supply circuit or a network connection device for both generating and regulating a sinusoidal high frequency voltage as well as the current fed to a load of variable resistance should be, at which the required voltage and the required amperage vary within wide limits, such as it z. B. is the case with a gas discharge lamp. at A particular difficulty arises with such a load, which is that one has to start with the load a very high regulated starting or ignition voltage is required, while the load is connected to the gas discharge after the initiation of the gas discharge With the aid of the current flowing through the load or the lamp, operated at a low voltage with a constant current must become. In known supply circuits is a Eochspannungs- ignition circuit is provided, which then, if the lamp passes a current, is switched off by a relay, through which the lamp is simultaneously connected to a feed circuit connected, which supplies a constant current at a low voltage. With these well-known Feed circuits are usually used with saturable chokes.

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According to the invention, a single feed circuit is now proposed which does not have any saturable chokes includes, but which can be operated by two different methods, one mode of operation for the ignition the lamp and the other mode of operation is intended for normal operation of the lamp. Does the feed circuit work as an ignition circuit, its output voltage is regulated, and when it powers the lamp in the normal way, its output current is regulated. A resonance circuit is provided here, which is only used as an ignition circuit during operation

^ regulated high voltage builds up. So that during normal If a constant high current is output when operating at a lower voltage, the current is regulated by that the entrance of a head; circuit supplied with high-frequency current pulses of constant amplitude and variable width will. The pulse width is regulated by a variable bias voltage, which is taken from the output of the feed circuit as well as a series of sawtooth pulses combined with the bias in a summing circuit will. A special feature of the invention is that a sawtooth wave is synchronous with the operation of a Oscillator is generated in that a capacitor via a first power conduction path during a certain period of time is charged, and that this capacitor is discharged via the oscillator during a second period of time, which is determined by the zero point crossing of the oscillator.

The invention and advantageous details of the invention are explained in more detail below with reference to schematic drawings of an exemplary embodiment. It shows

1 schematically shows a preferred embodiment of a feed circuit;

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Fig. 2 shows graphs of several waveforms occurring during operation of the feed circuit certain points appear; and

3 schematically shows the circuit of a preferred one Embodiment of an oscillator for generating periodic high-frequency square-wave pulses.

According to Fig. 1, the circuit shown can be connected for the purpose of operation with the aid of input terminals 002 and 004 to a normal power source which supplies a voltage with a root mean square value of 117 V at 60 Hz. A connected to the positive input terminal 002 ;? Scimitar 006 makes it possible to control the current supply to a transformer 100 which feeds the filament of a lamp 200, furthermore the supply of current to an AC-DC voltage conversion circuit 300, the output of which is via a switch 008 and a resistor 010 with a pulse of variable width generating generator 500 can be connected, as well as supplying power to one. Main circuit 600. The high-frequency sinusoidal output voltage and the output current are monitored by a voltage sensing circuit 800 or a current sensing switch 900, the output signals of which are fed to a bias circuit 1000. The output of the bias circuit 100 is fed to the variable width pulse generator 500 to effect changes in the width of the high frequency, constant amplitude pulses which form the input to the main circuit 600.

The AC-DC conversion circuit 300 includes a full-wave rectifier bridge made up of diodes with four diodes 302, 304-, 306 and 308, two inductors 3IO and 312, which are preferably shared by a common Core 314 are inductively coupled to act as a low pass filter to come into effect, as well as a capacitor 316, which returns essentially all of the alternating voltage.

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Incoming ripple of the DC voltage signal eliminated. A DC output voltage appears across capacitor 316 of about 120 V, which is fed to the high-frequency oscillator 400 via the switch 008 and the resistor 010, which is in the is described in more detail below with reference to FIG.

The DC voltage output signal of the AC voltage DC voltage conversion circuit 300 is connected to the variable width pulse generating generator 500 via a current limiting resistor 516, which is practically connected in series with a Zener diode 524 and between the output

fc output terminals of the AC-DC conversion circuit 300 lies. Thus, the generator 500 producing variable width pulses is provided with a constant DC voltage supplied by about 5 V; this generator comprises a charging circuit with a resistor 502 and a capacitor 520, whose common node is connected to the base of a transistor 526 via a resistor 504 is. A discharge circuit provided for the capacitor 520 comprises a diode 522 and a resistor 506, the are connected in series and between the mentioned node and the output terminal of the high-frequency oscillator 400 lie. While each of the positive high-frequency square-wave pulses that the oscillator 400 as an output signal

produced w dimensional, the discharge path is substantially blocked because the cathode of the diode is positive 522nd During each pulse, a charging current flows via resistors 516 and 502 to capacitor 520. Between successive pulses, capacitor 520 discharges via diode 522, resistor 506 and high-frequency oscillator 400. As a result, sawtooth pulses appear whose frequency is equal to the frequency of the output signal of oscillator 400 is at the junction between resistor 502 and capacitor 520, and these pulses are applied to the base of transistor 526 through resistor 504. These saw tooth impulses, together with the variable, are negative

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Bias voltage taken from bias circuit 1000 and applied to the base of transistor 526 amplifies a two-stage DC amplifier consisting of the transistor 526, a resistor 508, a Transistor 528 and a resistor 512 are composed, The combined with the variable bias voltage and common amplified sawtooth pulses form an input signal for a NAND gate 532, and the positive high frequency square wave pulses, which are taken from the oscillator 400, form the second input signal of the EAND gate 532. Only if these two positive input signals are above the threshold voltage of the ßand gate 532, a negative output signal generated. That is the interval during which the first input signal is above this threshold voltage, accordingly of the variable DC voltage component of the first input signal varies, so must the output pulses of the NAND gate 532 then vary accordingly. The the output signal of the NAlüD gate 532 forming negative pulses of variable width and constant amplitude are over a capacitor 518 is fed to the base of a normally conductive amplifier transistor 530, which thus through each pulse is rendered non-conductive so that it is positive to the lower terminal of a winding 614 of the main circuit 600 Supplies input voltage pulses of variable width.

The primary resistance 614 of the transformer 610 is with a resistor 604 between the positive terminal of the AC voltage-DC voltage conversion circuit 300 and the collector of transistor 530 connected in series. Every time the lower terminal of the primary winding 614 turns on a positive voltage pulse of variable width is supplied, the current flowing through this winding is interrupted, so that a pulse of appropriate width is induced in the secondary winding 612, which the base-emitter- ' Transition point of a power transistor 608 is supplied. As a result, transistor 608 becomes variable during

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Periods of time made conductive equal to the width of each input pulse which is generated in the secondary winding 612 of the transformer 610 in the manner described will. During these conduction periods of transistor 608, current flows from the positive terminal of the AC-DC converting circuit 300 via an input winding portion 618 of a Autotransformer 616 and the collector-emitter junction of transistor 608 to ground. Thus, in the output winding 618 and 620 of the autotransformer 616 generated high-frequency power pulses. These periodic performance) pulses, the frequency of which corresponds to the working frequency of the high-frequency oscillator 400 corresponds to a resonance circuit 700 fed.

The resonance circuit 700 includes a first capacitor 702 which is the output terminals of the autotransformer 616 bridged, a 'second capacitor 704 ·, the size of which is about corresponds to one third of the size of the first capacitor 702, as well as an inductance 706 »the one between the lower Terminals of capacitors 702 and 704- is connected, their upper terminals both to the positive output terminal the AC-DC conversion circuit JOO as well as with the filament 204 of the lamp 200 ″ via a center tap of the secondary winding 104 of the transformer 100 are connected. Further, the lower side of the capacitor 704 is one through a primary winding 916 Transformer 914 as well as a center tap of a second secondary winding 106 of the transformer 100 connected to the other filament 202 of the lamp. Those appearing at the output terminals of the autotransformer 616 High-frequency power pulses are fed to the resonance circuit 700, which forms part of a series circuit, and cause the resonance circuit to oscillate with the second harmonic of the frequency of the power pulses when the resistance the lamp 200 is high; d. i.e. when the lamp is in

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switched off state. As a result, the voltage appearing on the smaller capacitor 704 becomes large high so that the lamp 200 is ignited. The generated in this way at the relatively high resistance of the capacitor 704 Voltage has the frequency of the second harmonic of the high-frequency power impulses that form the resonance circuit 700 are fed, d. h..this frequency is 56 kHz. When the lamp 200 decreases after a gas discharge is initiated in the lamp, the capacitor becomes practically bridged by a shunt, and the resonance circuit, which now has a low resistance Load includes, works in the resonance state with the basic fi - qtic-n ^ The power pulses supplied to the resonance circuit 700, i. i.e., a frequency of 28 kHz. The inductance 706 also serves to keep unwanted fluctuations out of the load. The leakage inductance of the autotransformer 616 results in the required slowing down of the supply of the charging current to the capacitor 702, and this becomes the Auto transformer 616 loads the power transistor 608 to protect against strong inductive shock effects. By appropriate selection of the characteristic of the autotransformer 616 it is possible to minimize the dissipation of energy in transistor 608. ·

The voltage applied to the load from the resonant circuit 700 via the center taps on the secondary windings 104 and 106 of the transformer 100 is applied, is monitored by the voltage sensing circuit 800 connected to the Center tap of the secondary winding 106 is connected. A capacitor 804 is connected to this medium tap, which is connected to the junction between two series-connected diodes 808 and 810, which through a capacitor 806 and a resistor 802 connected in parallel therewith are bridged; the output signal is the Resistor 802 taken via an adjustable contact, which is connected to the bias circuit 1000 via an isolating diode 812

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connected. Diode 812 prevents the output current signal the current sensing circuit 900 is supplied.

The current sensing circuit 900 is constructed similarly, but it includes a transformer 914 and a fixed resistor 902 and a variable resistor 904; these resistors are connected in series and bridge the secondary winding 918; the primary winding 916 is with inductance 706 of the resonance circuit 700 and the center tap the secondary winding 106 of the transformer 100 connected in series. A capacitor 906 is on the one hand at the node * between the secondary winding 918 and the resistor 902 connected, and on the other hand connected to the node between two series-connected diodes 910 and 912 = the; these diodes are bridged by a capacitor 908. The output of circuit 900 becomes the node drawn between capacitor 908 and the anode of diode 912 and bias circuit 1000 across the same Line supplied as the output signal of the current sensing circuit 800.

The bias circuit 1000 includes resistors 1002 and 1004 h circuit between the base of transistor 526 and the outputs of the Spannungsfühlßchaltung 800 and the Stromfühl- are connected in. Series 900, and a resistor 1006 connected to the high voltage terminal of the serving for voltage control Zener diode 524 and the junction between resistors 1002 and 1004 is connected. These three interrelated circuits 800, 900 and 1000 form a feedback loop between the output of the feed circuit and the first stage of the two-stage DC amplifier, the variable width pulse generator 500 High-frequency alternating voltage applied to lamp 200 is rectified by diodes 808 and 810 and filtered by capacitor 806. the

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Voltage appearing on capacitor 806 is applied to resistor 802, from which a negative signal is passed -A contact is tapped and via the isolating diode 812 of the Bias circuit 1000 is supplied. This signal will is added by resistor 1004 to the steady positive bias voltage across resistors 1006 and 1002 of the Bias circuit is generated. If the voltage on lamp 200 is too high, the negative DC voltage changes, which is performed by the voltage sensing circuit 800, the bias at the base of transistor 526 by that it makes this tension less positive. As a result, the DC component of the signal that is fed as the first input signal to the NAND gate 532, is reduced to cause a reduction in the width of the output pulses of the generator 500. If on the other hand the of the lamp 200 is too low, the bias voltage at the base of the transistor 528 in the opposite Changed senses, increasing the pulse width.

The current sensing circuit 900 performs a similar function in that it generates a voltage that is applied across the two resistors 902 and 904 connected in series appear, which bridge the secondary winding 918 of the transformer 914, and that it feeds this voltage through the capacitor 906 to the rectifier diodes 910 and 912, which cause that capacitor 908 is negatively charged to ground. Changes the level of this negative charge will cause corresponding changes in the resulting bias on the Base of transistor 526 and corresponding changes in the Width of the output pulses of the generator 500, this process also taking place in the manner described.

Fig. 2a shows the pike-corner pulses appearing at the output of the oscillator 400 Fig. 2b shows the sawtooth pulses, which appear at the base of transistor 526, the dashed line being the resulting negative span *

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represents voltage supplied to bias circuit 100 by voltage sensing circuit 800 and current sensing circuit 900, respectively. According to E ¹ Ig. 2c, the width of the output pulses of the two-stage DC amplifier appearing at the collector of transistor 528 is reduced by the fact that the bias voltage becomes progressively negative. In contrast, Fig. 2d shows the voltage appearing at the base of the transistor 526th of the first stage when the negative voltage generated by the voltage sensing circuit and the current sensing circuit is relatively low, so that the collector of the transistor 528 in Fig. 2e the pulses shown are of greater width. Figure 2f shows the waveform of the Vase voltage appearing at the base of transistor 530 during operation of the circuit. As long as there is no output signal from NAND gate 532, the base of this transistor is at a low positive voltage. As soon as the NAND gate 532 emits a negative pulse, since its first and second gates are simultaneously supplied with input signals which are above the threshold value, this negative pulse is supplied via the capacitor 518 to the base of the transistor 530 in order to make it negative, so that the supply of current from the positive terminal of the AC-DC voltage conversion circuit 300 via the resistor 604, the primary winding 614 of the transformer 610, the resistor 602 connected in parallel therewith and the collector-emitter junction of the transistor 530 is interrupted. Thus, a pulse appears on the secondary winding 612 of the transformer 610, the length of which corresponds to the duration of the non-conductivity of the transistor 530. The power transistor 608 becomes conductive for a period of time of similar length and causes a current pulse of equal duration to be generated in the input winding section 618 of the autotransformer 616. According to FIG. 2g, the collector of transistor 530, which is normally practically at ground potential, when this Transistr

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is conductive, positive, during time periods which directly correspond to the duration of the negative pulses 552 the base of transistor 550 supplies the NAND circuit.

Fig. 5 shows schematically the circuit of the I'ig. 1 oscillator 400 shown only as a diagram block.It is true that the task of this oscillator could be fulfilled by any oscillator that generates high-frequency rectangular pulses and releases a current path of low resistance to earth via its output terminal as soon as the value between the pulses is zero the circuit according to I'ig. 5 is preferably used because of its practicality and economy. This oscillator circuit essentially comprises a transistor switch assigned to the first stage, the output of which is connected to the input of a transistor switch of the second stage, a resonant series circuit connecting the input of the switch of the first stage to the output of the switch of the second stage. The output of the first stage switch is connected to the input of that switch through a feedback loop which includes a resistor 419 to cause the oscillator circuit to operate more linearly and to enable oscillations to be generated.

In the preferred embodiment shown in FIGS the feed circuit have the different Circuit elements have the following electrical values:

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Resistances

010 -15 kilo ohms IC) TC 012 - 470 ohms IC) TP 404
406 - (ic)
-ic IC) TC 408 - (IC) IC) TC 410 - (ic) - 1 kilo ohm TP 412 - (ic) -10 kilohms 414 - 100 ohms 416 - - 10 kilo ohms 418 _ - 10 kilo ohms 420 - 4.7 kilo ohms 502 - 2 kilo ohms ic) 504 -1.5 kilohms IC) 506 - 2 kilo ohms IC) 508 - 20 kilo ohms - 2N5183 512 - 33 ohm - 2N5183 5H - 100 ohms - OTS411 516 - 10 kilo ohms - MJE34O 602 - 10 kilo ohms NAUD gate 604 - 10 kilo ohms 802 Transistors 902 430 904 432 1002 434 1004 436 1006 438 440 442 444 526 528 530 608

532 - united with oscillator 400; SN7400N

- 2160121 Capacitors Microfarads Inductors 316-200 Picofarad 422 - 8.2 Microfarads 518-0.068 ti 520-0.068 Il 606-0.068 ti 702 - 0.1 Il 704-0.033 Il 804 - 0.001 ■ ti 806 - 0.001 U 906-0.068 It 908 - 1.0

310-0.05 henry 312-0.05 "424-4.3 millihenry 706-0.36 millihenry

Diodes

302 304 306 -

Varo part no. VS

IC) IC)

1N5221 1N5O59 1N5O59 1N914 1N914 1N9H

Transformers

100 - primary winding 102: 1145 turns; Secondary windings 104 and 106: turns.

610 - primary winding 614:

Turns; Secondary winding 610: 150 turns.

616 - winding part 618:

Turns; Winding part 620: 14 turns.

914 - primary winding 616:

Turns; Secondary winding 918: 150 turns.

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All information and characteristics contained in the documents, in particular the spatial design of the Subject of the registration, insofar as they are individually or in combination new compared to the state of the art, claimed as essential to the invention.

-Expectations-

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Claims (11)

EXPECTATIONS (Ij current and voltage-regulated supply circuit arrangement for a load with variable resistance, with a first circuit for converting alternating current energy into direct current energy, characterized in that second circuits (400,500) are provided which generate high-frequency pulses depending on the level of the bias signal supplied to it of variable width and substantially constant amplitude, and third circuits (600,700) connected to the load with the variable resistor and operating in response to the output of the second circuits and producing high frequency output power at high voltage when the resistance of the load is high is, and generate high-frequency output energy at low voltage when the resistance of the load is low, and that fourth circuits (800,900,1000) are provided which the variable bias signal for the second circuits (400, 500) depending on deviations in the output voltage and of the output current from their predetermined setpoints to vary the width of the output pulses of the second circuits. 2. Feed circuit arrangement according to claim 1, characterized in that the first circuit is a Diode bridge circuit (302, J5O6,304 ^ 308) with first and second input and output terminals, further comprising first and second inductors (310, 312) of which each having a first and a second terminal, the first terminal of the first inductor being connected to the first output terminal the diode bridge circuit is connected, while the first terminal of the second inductance in the second Output terminal of the diode bridge circuit is connected, and one between the second terminals of the first and the second 209828/0573 J? Inductance connected filter capacitor ($ 16). 3. Feed circuit arrangement according to claim 2, characterized in that the first and the second Inductance (310, 312) are inductively coupled by a common magnetic core (314 ·). 4-. Feed circuit arrangement according to Claim 1, characterized characterized in that the second circuits include a high frequency oscillator (400) for generating high frequency Include square-wave pulses, furthermore a sawtooth pulse generator operating synchronously with the high-frequency oscillator (502, 520, 522, 506), one connected to the sawtooth pulse generator first amplification circuit (526, 508, 528, 512) for amplifying the output signal of the sawtooth pulse generator and the variable bias signal, a threshold responsive circuit (532) having one connected to the Output of the first amplification circuit connected to the first input and one to the output of the high-frequency oscillator connected second input, the output pulses of constant amplitude and variable width according to the Length of time generated during which both input pulses exceed their threshold value, as well as a second amplification circuit (530, 516, 518) for generating output pulses of predetermined polarity, constant amplitude and variable width according to the width of the output pulse9 the circuit responsive to the threshold values. 5. Spei se circuit arrangement according to claim 4 ·, «thereby gekennzeichn et that the second circuits additionally comprise a voltage regulating device (516 »524 ·). 6. Feed circuit arrangement according to claim 4, characterized in that the high-frequency oscillator (4-00) a first stage with a transistor switch (4-16, 209828/0573 418, 420, 428, 438, 440, 442, 444) and a feedback loop (419), further comprising a second stage having a. Transistor switches (404, 406, 408, 410, 412, 426, 430, 432, 434, 436) and a resonance circuit designed as a series circuit (422, 424), which connects the input of the transistor switch of the first stage to the output of the transistor switch the second stage connects. 7. Feed circuit arrangement according to claim 6, characterized in that the high-frequency oscillator (400) causes a discharge current path for the sawtooth pulse generator via the second transistor switch during the periods between adjacent high frequency Square pulses closes. 8. Feed circuit arrangement according to claim 4, characterized in that the chn et chnzei on threshold values responsive circuit comprises a HAND gate (532). 9. Feed circuit arrangement according to claim 5j characterized in that the sawtooth pulse generator has a capacitor (520) and a capacitor connected in series with it, includes charging resistor (502, 516) connected to the voltage regulating device, as well as a "diode (522) and a discharge resistor (506) which are a series connection between the node between the capacitor and form the charging resistor on the one hand and the output terminal (446) of the high-frequency oscillator (400). 10. Feed circuit arrangement according to claim 1, characterized in that the third circuits a transformer (610) having a primary winding (614) and a secondary winding (612), the primary winding of which is connected in series with the first circuit and the second circuits, furthermore an autotransformer (616) with a first, a second and a third terminal, a power transistor (608), which with its 209828/05 7 3 Base and its emitter bridged the secondary winding of the transformer, and its collector via the second and the first terminal of the autotransformer is connected to the first circuit, as well as a resonance circuit (700), which is connected between the first and the third terminal of the Spartran sformatοrs and a high voltage generated by the fact that it is in the state of resonance with a first high frequency depending on which it is via the autotransformer supplied input power pulses works when the resistance of the load is high and that in the resonance state with a second high frequency depending on input power pulses supplied to it via the autotransformer works when the resistance of the load is small. 11. Feed circuit arrangement according to claim 1, characterized in that the fourth circuits comprise a voltage sensing circuit (800) which generates an output voltage deviating from a predetermined normal value as a function of deviations of the output voltage of the feed circuit arrangement from a predetermined value, furthermore a current sensing circuit (900), which generates an output current deviating from a predetermined normal value as a function of deviations of the output current of the supply circuit arrangement from a predetermined value, and a voltage circuit. (1000), which is connected to the voltage sensing circuit and the current sensing circuit and operates as a function of the output voltage supplied to it and the output current supplied to it, in order to supply the aforementioned variable bias signal to the second circuits. 209828/0573