RU1805554C - Electronic starter for initiating fluorescent lamps with preheated electrodes - Google Patents

Abstract

SUMMARY OF THE INVENTION: An electronic starter comprises two rectifiers, an isolation transformer, a switching transistor, and a power transistor control device consisting of four functional units connected in a ring circuit. 1 ill.

Description

The invention relates to electrical engineering, in particular to ignition devices for tubular fluorescent lamps with preheating electrodes, powered from AC networks with a frequency of 50-60 Hz or 400 Hz and a voltage of 115-127 V or 220-240 V through ballast devices of inductive or inductive capacitive types that provide ignition of fluorescent lamps of all types and ratings in terms of power, including at low ambient temperatures.

The purpose of the invention is to increase the reliability of ignition of a fluorescent lamp.

The drawing shows a complete circuit diagram of an electronic starter for a fluorescent lamp with preheating electrodes, powered by an alternating current main through a ballast device of inductive or inductive-capacitive type.

In the drawing, the numbers 1 and 2 indicate the terminals connected to the AC network

current, to which the ballast choke 3 and the fluorescent lamp 4 are connected with the preheating electrodes 5 and 6 and contacts 7 and 8, through which an electronic starter is connected to the lamp (all other circuit elements). The electronic starter contains a first bridge rectifier, consisting of four avalanche type diodes 9-12 (for example, KD206 V mesa diffusion silicon diodes) and an isolation transformer 13 with a primary winding 14 and a secondary winding 15, and the bridge rectifier is connected to pin 8 through a winding 14. A switching transistor 16 is connected to the diagonal of the bridge, connected in series with a low-resistance resistor 17. The power transistor control device consists of four functional units connected in a ring circuit, which limited in the drawing by dashed rectangles: blocks 18, 19, 20 and 21.

Block 18 consists of a series-connected resistor 22, a zener diode 23, and

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a capacitor 24, forming a voltage-sensitive circuit on the lamp, and a series-connected dinistor 25, resistors 26, 27, 28 with a capacitor 29 shunting the resistor 27, which form the base circuit of the transistor 16, the first circuit is connected between the emitter and the collector of transistor 1.6, the second - between the emitter of transistor 16, the common point of the zener diode 23 and capacitor 24 and connected to the base of transistor 16.

Block 19 consists of four diodes 30, 31, 32, 33 connected by a bridge circuit and a transformer 13 (removed from block 19 in the drawing), the secondary winding 15 of the transformer 13 is included in one diagonal of the rectifier bridge with contacts 44 and 45, and the second the diagonal of the bridge is connected to the emitter of the transistor 16 and the capacitor 24. The second output of the block 19 is connected to the voltage doubling circuit of the block 20 through the diode 34 and the capacitor 35.

Block 20 with a voltage doubling circuit consisting of diodes 34 and 36 and capacitors 35 and 37 also contains a single-junction transistor 38, resistors 39,40 and 17, and a capacitor 41, the capacitor 35 being connected to the common point of the diodes 34 and 36, the diode 36 is connected by a cathode with a resistor 39, a capacitor 37 and a single-junction transistor 38, a capacitor 37 is connected to the emitter of the transistor 16, to a low-impedance resistor 17 and a capacitor 41, which is connected to the emitter of the transistor 38 and the resistor 39, and the transistor 38 is connected to the second base by a second base to resistor 40 and both res torus 17 and 40 are connected with the diodes 9 and 10 of the first bridge rectifier.

Block 21 consists of a resistor 42 and thyristor 43 connected by the anode to the common point of the elements 26, 2J, and 29 in block 18 and the cathode to the common point of the elements 16, 28, 31, 33, 37 and 41, and the control electrode thyristor 43 through a resistor 42 is connected to a common point of elements 38 and 40.

The starter along with the lamp and ballast choke operate as follows.

When the mains voltage is applied between terminals 1 and 2, this voltage is through the inductor 3, the electrodes 5 and 6 of the lamp 4, the primary winding 14 of the transformer 13, the diodes 9, 10, 11 and 12 and the resistor 17 is applied between the collector and the emitter of the closed transistor 16, and also - to a chain of elements 22; 23 and 24, through which a current begins to flow, charging the capacitor 24. When charging the capacitor 24 to the operating voltage of the dynistor

25 there is a breakdown of the dinistor and the current from the capacitor 24 through the dinistor 25 and the resistors 26 and 27 enters the base of the transistor 16; transistor 16 opens, shorts the diagonal of the first bridge (diodes 9,10,11, 12), and through inductor 3, electrodes 5 and 6, winding 14, bridge rectifier diodes 9, 10,11 and 12, resistor 17 and transistor 16 a current begins to flow, under the influence of which the electrodes 5 and 6 are heated and an alternating voltage is generated on the winding 15, which enters the second bridge from the diodes 30, 31, 32 and 33.

A rectified voltage is formed on the second diagonal of the second bridge, and the current from this bridge charges the capacitor 24, thereby ensuring long-term holding of the transistor 16 in the open state. At the same time under the action

0 of the voltage removed from this bridge through the diode 34 and the capacitor 35 by means of the diode 36, a doubled voltage (with respect to the capacitor 24) is formed on the capacitor 37, which ensures the flow

5 of the operating current through the elements 38, 40 and 17 and charging the capacitor 41 through the resistor 39 for a time, for example 2 s, sufficient to completely warm the electrodes 5 and 6. In this case, a pulsating current flows through the resistor 17

0 the rectified heating current of the electrodes and the relatively small current of the transistor 38, and the capacitor 41 is smoothly charged and the sum of the voltages on the capacitor 41 is applied to the emitter of the element 38 and

5 pulsating voltage across the resistor 17. At the moment when the sum of these voltages for the first time reaches the response voltage of the element 38, and this moment corresponds to the moment of maximum force

0 current in the electrode heating circuit and in inductor 3, a single-junction transistor 38 is triggered and a voltage pulse is applied to the control electrode of thyristor 43 in block 21, opening the thyristor, which shunts the base current circuit of transistor 16; the transistor 16 is closed, the capacitor 24 is discharged through the elements 25,26 and 43, the current through the winding 14 is stopped, the voltage on the winding 15 disappears

0 and the charging of the capacitor 24 through the bridge rectifier (30,31,32,33) stops, the Capacitor 29 in the base circuit of the transistor 16 provides the formation of a pulse of negative polarity on the base

5 of the transistor at the time the thyristor 43 is triggered.

The cessation of current flow through the heating circuit of electrodes 5 and 6 causes the generation of an overvoltage pulse on inductor 3, this pulse is applied

to the lamp 4 and through the winding 14 and diodes 9, 10, 11, 12 to the transistor 16 and to the chain of elements 22, 23, 24,

Further operation of the device can occur in four different ways.

Under the action of an overvoltage pulse having a steep leading edge, the discharge gap of lamp 4 will be broken and a current of about 1/4 of the mains voltage will pass through it when the electrodes are warm, the reverse voltage will be applied to the lamp and it will enter normal operation . In this case, the voltage on the lamp will be less than the threshold voltage on the zener diode, the current through the circuit from the elements 22, 23, 24 will not flow, the capacitor 24 is discharged and the starter will return to its original state, waiting for the de-energized state to turn on the lamp again after turning it off or waiting for the lamp to go out for some other reason.

 The lamp did not light up under the action of an overvoltage pulse, then the voltage on the inductor 3 rises to the avalanche voltage of one of the diodes in the first bridge of elements 9, 10, 11, 12, which, for example, for 2D 206V diodes is 600 B, an overvoltage pulse with a flat top with an amplitude of 600 V is generated on the lamp and on the transistor 16, the dross current starts flowing through the diodes 9, 10, 11, 12, which stops during the order of a millisecond, while the circuit consists of elements 22, 23, 24 a current pulse will also pass that cannot charge capacitor 24, since the thyristor 43 is open at this time. After the end of the pulse, the mains voltage from pins 7 and 8 is applied to the electronic starter and the starter cycle is repeated.

The lamp is lit, it works stably, but due to some deactivation of the cathodes, it has an increased instantaneous value of the re-ignition voltage, and at the moment of changing the direction of the current through the lamp, very short voltage surges are formed on it. In this case, short current pulses flow through the elements 22 and 23, charging the capacitor 24, however, the dynistor 25 does not operate, since the charge from the capacitor 24 flows through the diodes 34, 36, the transistor 38, and the resistors 40 and 17.

The lamp lit up, but due to the strong deactivation of one of the electrodes, it switched to the rectifying mode, which is dangerous for

In operation, throttle 3, or the voltage on it, has increased very much due to the deactivation of both cathodes and it burns on alternating current with an increased voltage, 5 indicating the need to replace the lamp. In this case, a current of such a force begins to flow through the elements 22, 23 and 24, at which the starter operates in the usual way, shunts the lamp, extinguishes it and heats its electrodes for 2 s, and then ignites the lamp again. Periodically turning the lamp on and off with a starter indicates the need to replace it; starter in this case should not be replaced.

5 Thanks to the starter, the lamp is prevented from operating in a continuous rectifier mode that is dangerous for interrogation.

The starter is characterized by the following positive qualities.

0 In the event that one of the lamp cathodes burns out or the cathode heating circuit is interrupted, the starter is disconnected from the power supply and the control gear with the lamp ceases to function.

5 In the event of sparks between the lamp pins and lamp holder contacts, as well as when overvoltage surges appear in the network, no damage to the elements

0 starter, which is protected by avalanche diodes at the input.

The peculiarity of constructing the electric circuit of the starter and the sequence of operation of its circuits provide non-critical selection of the parameters of the elements, a wide range of tolerances on the values of the used electrical elements is possible.

Starters operate normally both with fluorescent lamps having low resistance cathodes (supply voltage during heating up to 6.5 V), and with fluorescent lamps having high resistance cathodes (heating voltage up to 11 V).

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The amplitude of the single high voltage pulses generated by the lamp during the lamp ignition is limited, does not exceed the voltage of the avalanche protodes of the starter in the first bridge, and if diodes with a higher avalanche voltage are selected, the lamps are ignited at low ambient temperatures.

5 The moment of generation of a single ignition pulse in time coincides with the amplitude value of the current in the ballast choke, thereby achieving a high probability of lamp ignition on the first try.

If the lamp fails to light on the first attempt, the ignition is repeated for a period of several seconds.

The constant current consumption of the starter when the lamp is working properly is very small and is determined by the leakage current of the zener diode in the starter at voltages lower than its reference voltage.

The starter according to the indicated scheme, with changes in the ratings of some elements, can be operated in alternating current networks with a frequency of 50-60 and 400 Hz; depending on the type and number of lamps lit, some elements of the starter circuitry must also be changed.

The starter uses a low-power isolation transformer (0.5 W) with a primary and secondary voltage of the order of 5 V, which is characterized by a lower manufacturing time than the transformer in the prototype for a primary voltage of 220 V,

The starter can be used to ignite - immediately two series-connected lamps, for example, with a power of 15 or 20 W; In this case, the starter isolation transformer must have a large power and an additional winding for heating the cathodes of two lamps connected in series.

Using a starter will expand the scope of applications of fluorescent lamps with electromagnetic ballasts, for example, it will be possible to use them in vehicles and in light signaling, where 100,000 or more inclusions must be guaranteed, v

The starter generates single pulses with a small percentage of higher harmonic components, and is therefore a significantly weaker source of electromagnetic interference over the network and field than the glow discharge starter.

For mounting the starter in the apparatus, it is not necessary to use a starter block, since all its parts operate in lightweight modes and starters do not need to be replaced.

If necessary, it is possible to easily change the heating time of the lamp cathodes by changing the value of the resistor in the emitter circuit of a single-junction transistor.

Most starter electrical elements operate with low power dissipation for a limited time, so in the future it will be possible to produce a hybrid circuit using unpacked semiconductor elements and low power resistors, to

which connects several mounted electrical elements.

Claims (1)

SUMMARY OF THE INVENTION An electronic starter for igniting fluorescent lamps with preheating electrodes, comprising a bridge rectifier, a bipolar transistor connected to a DC diagonal of a bridge rectifier, a bipolar transistor control unit including first and second resistors, two series-connected diodes, a third a resistor connected between the base and the emitter of the bipolar transistor, and a fourth resistor and capacitor connected in series, as well as conclusions for connecting to luminescent electrodes of a fluorescent lamp, one of which is connected to the first output of the diagonal of the alternating current of the bridge rectifier, characterized in that, in order to increase the reliability of ignition of the fluorescent lamp, an additional isolation current transformer, a zener diode, a dynistor, and a single junction are introduced into the control unit of the bipolar transistor a transistor, a thyristor, four capacitors, four resistors and a bridge rectifier, while the positive diagonal of the additional bridge rectifier is connected to the anode the first diode, through the series-connected dynistor and the first and second resistors - to the base of the bipolar transistor, through the series-connected zener diode and the fifth resistor - to the collector of the bipolar transistor, and through the second capacitor - to the emitter of the bipolar transistor, the negative output of the diagonal of the additional rectifier the capacitive bridge is connected to the emitter of the bipolar transistor, to the cathode of the thyristor, to the combined terminals of the fourth resistor and the first and third capacitors, the anode of the thyristor is connected to the combined the leads of the first and second resistors and the fourth capacitor, the second terminal of which is connected to the base of the bipolar transistor, the thyristor control electrode is connected through the seventh resistor to the first base of the single-junction transistor and to the eighth resistor, the second terminal of which is connected to the negative terminal of the main rectifier bridge and the second terminal of the fourth resistor, the cathode of the second diode is connected to the second terminal of the first capacitor, the second base of the single-junction transistor and the first terminal of the sixth th resistor, the second terminal of which is connected to the second terminal of the third capacitor and the emitter of the single-junction transistor, the cathode of the first diode through the fifth capacitor is connected to one of the terminals of the alternating current diagonal of the additional rectifier bridge connected by the alternating current diagonal to the secondary winding of the isolation current transformer, the primary winding of which is connected between the second alternating current diagonal output a main rectifier bridge and a second terminal for connecting a glow electrode of a fluorescent lamp.