RU2409013C1 - Intelligent electronic ballast for gas-discharge high pressure lamps - Google Patents

Abstract

FIELD: instrument making. ^ SUBSTANCE: half-bridge converter is controlled with variable frequency generator and relative pulse duration, which in its turn is controlled as per relative pulse duration with low pass filter signal, and as per frequency - with current sensor of the lamp. Priority signal supplied from rectifier connected to the lamp is supplied to control input as per generator frequency. Outputs of current sensor of the lamp and voltage rectifier of the lamp are connected to power control device. Power control device has logic unit analysing operating modes of the lamp and ballast as a whole and generating control and correction signals. Outputs of power control device are connected to the lamp lighting device and to generator. In addition, to electronic ballast there built in is bidirectional modem of data transmission via network wires, dedicated line or radio channel which is connected to power control device. ^ EFFECT: enlarging functional capabilities. ^ 4 cl, 1 dwg

Description

The present invention relates to the field of electrical engineering and is intended for use as ballast of high-pressure discharge lamps when they are supplied with a current of industrial frequency with a voltage of 160-250 V at a frequency of 50 ÷ 60 Hz.

It is known that when feeding high-pressure gas-discharge lamps (for example, mercury DRI type or sodium type DNaT) from an industrial AC mains with a voltage of 160 ÷ 250 V and a frequency of 50 ÷ 60 Hz, ballasts (PRA) are used [1].

Traditional electromagnetic ballasts contain a current-limiting reactor (electromagnetic inductor), connected in series with the lamp, and an ignition device that generates high-voltage pulses for igniting the discharge.

The use of such ballasts leads to the following disadvantages:

- flicker;

- instability of the power and luminous flux of the lamp during voltage fluctuations in the mains;

- low power factor;

- a large mass of the current-limiting reactor of the ballast, including the presence of a separate pulse start-up unit and the need to use an additional large-capacity capacitor to improve the power factor;

- lack of ability to control the light flux.

These shortcomings are eliminated by using electronic ballasts (electronic ballasts) for powering lamps, another common name for which is electronic ballasts (EBs) [2].

The use of electronic ballasts, in particular, provides:

- high power factor (cosφ = 0.98-0.99);

- lack of low-frequency pulsation of the light flux;

- longer lamp life, due to the ability to control power (the so-called "soft" start), and stabilization of power on the lamp during its aging;

- the ability to adjust power;

- high efficiency (up to 95%);

- an order of magnitude smaller weight and size parameters.

Known electronic ballast, which contains:

a half-wave rectifier connected to a power source, an increased current frequency converter, an electronic ballast with an ignition device, an input noise suppression filter, a varistor-based surge protection device, a rectifier designed to connect the device to an alternating current source, a power factor corrector designed to generate current consumption [3].

Technical characteristics of such electronic ballast fully comply with the requirements of domestic standards [4].

The disadvantages of such an EB include the following:

- EB is applicable only when supplying low-pressure discharge lamps and cannot be used when supplying high-pressure discharge lamps because of differences in starting and working current-voltage characteristics, since when working with low pressure lamps at the time of start-up, the initial voltage is practically equal to or exceeds the operating voltage, while on a high-pressure discharge lamp at the time of ignition, the voltage does not exceed 10 ÷ 15 V due to the low initial pressure inside the bulb.

Closest to the invention is an electronic ballast (EB) for high-pressure discharge lamps, which contains the following main components: surge protection device, noise filter, rectifier, power factor corrector, converter, ignition device and power control device [5].

The electronic circuit is based on a half-bridge voltage converter using power MOS transistors (VT2 and VT3) operating at an increased modulation frequency. To control the power MOS transistors of the converter, an integrated microcircuit of the high-voltage driver IR 2155 is used, which ensures reliable start-up, stable operation of the electronic components in a wide temperature range and a low level of dynamic losses in transistors.

Discrete control of the modulation frequency of the converter and, accordingly, the lamp current and power consumption is carried out by changing the capacitance of the timing RC circuit of the control chip using the key S, in the circuit of which an additional capacitor is included. The converter provides lamp power with an increased frequency current in two modes - full power mode and power consumption mode at the level of 50% of the nominal one, which gives adequate control of the lamp brightness.

The modes are switched using a power control device, including a comparator, to the input of which a rectified mains voltage is supplied, a pulse selector in duration, and a memory device that controls the S key. When connected to a network, the full power mode is always set in the electronic module. The command to switch the mode comes from the control station, the power part of which is a thyristor switch, and consists in interrupting the supply mains voltage for a time equal to half its repetition period. The control action is identified by the electronic power control device and changes the state of the storage device. The key S opens, increasing the operating frequency of the inversion, and the electronic switch goes into low power mode. With a repeated control action, the EB returns to its original state. The presence in the control device of the power of the pulse selector for the duration eliminates false alarms in case of failures that occur in the network.

The use of an active power factor corrector solves the problems of compatibility of the power supply with the mains. The corrector is made according to the scheme of a boost pulse converter using a powerful MOS transistor (VT1), which is controlled by a specialized integrated circuit VC 33262 [6], which ensures power consumption with a power factor in the nominal mode of 0.98. The power factor corrector generates a quasi-sinusoidal current in the reactor, which is turned on at the output of the rectifier, and the noise filter reduces the level of high-frequency harmonics in the current consumed. The power factor has a high value under all possible modes in the voltage range of 220 V ± 15%. The use of the corrector provides high stability of illumination when the voltage of the supply network changes due to voltage stabilization in the DC power circuit.

The interference suppression filter, in addition to smoothing high-frequency ripples of the consumed current, arising during the operation of the active power factor corrector, provides suppression of radio interference generated by electronic components. The presence of an active corrector and an interference suppression filter ensures compliance with the IEC 555.2 standard, which strictly regulates the level of higher harmonics of the current consumed from the mains [7].

At the input of the interference suppression filter, a traditional surge protection unit is included, including a varistor and a fuse. A thermistor with a negative temperature coefficient of resistance connected in series with the fuse limits the inrush of the input current when the electronic ballasts are connected to the network, due to the charge of the capacitive filter at the input of the converter.

The lamp is ignited by applying high voltage to its electrodes. The voltage required for ignition can be obtained in the resonant circuit or generated by a special circuit in the form of repeating pulses. Reliable ignition of a lamp in a high-frequency resonant circuit requires a voltage whose effective value exceeds 1 ÷ 1.2 kV, which leads to a 3 ÷ 4 times current overload relative to the rated current of the lamp and, as a result, an increase in the installed power of power semiconductor switches converter, reduce reliability and additional power loss in idle mode. The prolonged idle mode that occurs when the lamp fails or is absent becomes practically unacceptable, therefore, a pulsed ignition system is used to start the lamp.

The ignition device is made according to the well-known dynist trigger circuit, forming high-voltage voltage pulses with an amplitude of 3 ÷ 4 kV. The circuit contains a storage capacitor, the charge of which is produced through resistors from the converter power buses. The capacitor is discharged through the dynistor to the additional winding of the reactor, which causes the formation of a high voltage voltage pulse on its power winding in the form of a damped harmonic signal, which is applied to the lamp electrodes through power switches and a separation capacitor. After the lamp is ignited, the oscillation ceases, since the load circuit changes the charge condition of the capacitor and does not allow the voltage on it to reach the threshold value of the dynistor.

The ignition of the lamp is followed by a relatively long (several minutes) process of its ignition. During this time, the voltage on the lamp rises from 20 ÷ 30 V to a nominal value of approximately 100 V for DNaT lamps with a power of 250 W. The current is limited by the resistance of the reactor and its effective value does not exceed 3.1 A, which makes 120 ÷ 130% of it nominal value. The value of the operating frequency was chosen near 20 kHz to exclude the so-called acoustic resonance and its accompanying phenomena: instability of the light flux, local overheating of the walls of the discharge tube, leading to its possible cracking.

The mentioned electronic device fully complies with the requirements for electronic ballasts [4] and the features of high-pressure lamps, which are the load of electronic ballast.

The disadvantages of this technical solution include the following:

- the frequency of operation of the lamp power converter is fixed, which leads to a high level of interference and an increased inrush current due to a change in the conductivity of the lamp during heating;

- there are no devices for monitoring and diagnosing the lamp, which leads to emergency conditions during the development of the lamp life and during transient conditions in the primary network.

The following failures may occur:

a) high-voltage breakdown of insulation when trying to set a hot lamp on fire and, as a result, accelerated lamp life;

b) an increase in power consumption during mirroring of the lamp (i.e., deposition of a thin layer of metal on the inner surface of the lamp bulb due to erosion of the lamp electrodes);

c) the half-bridge converter coming out of a stand during breaks in the lamp power supply circuit due to the appearance of an idle mode and, as a result, a violation of the operating modes of the transistors of the converter;

d) the ambiguity of the power control mode when several lamps are on the same power line due to the possibility of a failure of the trigger of the power control device.

Object of the invention:

- reduction of lamp energy consumption up to 40%;

- optimization of lamp operating modes and thereby multiple extension of lamp life;

- reducing the ripple coefficient of the lamp, which allows to improve the lighting conditions;

- control of lamp operation modes both in group control mode and in personal addressing mode;

- providing remote diagnostic modes, automated calibration and tuning.

This is achieved due to the fact that in the electronic ballast for high-pressure discharge lamps containing a noise suppression filter connected in series, an overvoltage protection device, a rectifier, a power factor corrector, a half-bridge converter with an integrated variable frequency generator, to the input of which an output of the power control device is connected, and the primary winding of the inductor-transformer, an isolation capacitor and a lamp are sequentially connected to the output, and to the primary winding A pulse ignition device is connected to the throttle transformer, a logic unit is additionally introduced into the power control device, a lamp current sensor is connected again, connected in series with the lamp, a newly introduced low-pass filter is connected to the common point of the throttle transformer and isolation capacitor, the output of which is connected to the input a variable frequency generator and with one of the inputs of the power control device, a newly introduced detector is connected to a common point of the isolation capacitor and lamp voltage, the output of which is connected to the input of the variable frequency generator and one of the inputs of the power control device, and a lamp current detector is introduced, the input of which is connected to the lamp current sensor, and the output - with the input of the variable frequency generator and with one of the inputs of the power control device , the rectifier output and the output of the power factor corrector are connected to the input of the power control device, one of the outputs of the power control device is connected to the input of the pulse ignition device, the output of which connected to the secondary winding of the inductor-transformer, and the second output of the power control device is connected to the control input of the variable frequency generator.

Additionally, a bi-directional data transmission modem via network wires was introduced into the electronic ballast, one input-output of which is connected to the output of the noise suppression filter, and the other input-output is connected to the input of the power control device.

As a modem, a bi-directional radio modem or a leased line modem can be used, which can solve similar problems of controlling and transmitting information between the IEB and the remote control device.

In the solutions of a similar problem known to science and technology, the use in electronic ballast control devices (electronic ballasts) for high-pressure gas discharge lamps of the logic units built into the power control device that control the lamp and control its operation modes, as well as bidirectional micromodems, ensuring the transmission of electronic ballasts generated by electronic ballasts via network wires to the power control device and transmitting control signals from the remote control device to the electronic ballast input.

The invention is illustrated in the drawing, which schematically shows the claimed design of an intelligent electronic ballast, where:

1 - anti-interference filter;

2 - surge protection device;

3 - rectifier;

4 - power factor corrector;

5 - variable frequency generator;

6 - half-bridge converter;

7 - low pass filter;

8 - lamp voltage detector;

9 - lamp current detector;

10 - pulse ignition device;

11 - a lamp;

12 - power control device with an integrated logic unit;

13 - bidirectional modem;

L1 - throttle transformer;

C1 is an isolation capacitor;

R1 - lamp current sensor.

When working with lamps of the DRI and DNAT type, the operation of an intelligent electronic ballast is as follows.

A power control device 12, which is additionally equipped with a logic unit, monitors the output voltage at the output of the rectifier 3 and provided that the input voltage of the network is in the allowed operating voltage range (for example, 170 ÷ 240 V, which is set when the logic unit of the control device is configured power 12), as well as the output voltage of the power factor corrector 4 is in the operating range (390 V ± 5%, the recommended value for the rated voltage of 220 V), turns on the ignition mode lamp 11, at which the output frequency of the half-bridge converter 6 is maximum. Next, the power control device 12 generates a command for the operation of the pulse ignition device 10, which with a frequency of 10 ÷ 15 Hz supplies the ignition pulses to the lamp 11 through the inductor-transformer L1. If the lamp lights up, the current sensor R1 shows the starting current of the lamp and the power control device 12 goes into lamp heating mode. If after supplying a series of 10 pulses the lamp did not light up, then the power control device 12 tries to light the lamp twice after 1 second, and if in this case the lamp does not light up, further operation is blocked until the supply voltage is removed, and the power control device 12 generates a signal “Lamp malfunction - open or no lamp”, thereby protecting the entire device from constantly repeating high-voltage pulses (for reference: the amplitude of the ignition pulses must be at least 2.5 kV for DNaT lamps, and not less than 1 kV - for lamps of the DRI type).

Let us consider in more detail the main modes of operation of intelligent electronic ballast.

1. The mode of heating the lamp.

At the initial moment after ignition of high-pressure lamps, the voltage on the lamp does not exceed 10 ÷ 15 V and the thermal conductivity of the arc is minimal. At this moment, depending on the orientation of the burner, uneven heating of the lamp electrodes occurs and, as a result, their erosion. As a result of this phenomenon, at the same voltage on the lamp, the lamp current I ₁ in one polarity of the applied voltage is not equal to the current I ₂ in another polarity. Ultimately, the charge Q ₁ introduced into the separation capacitor in time t ₁ equal to the product (t ₁ · I ₁ ) is not equal to the charge Q ₂ selected from the separation capacitor in time t ₂ , where t ₁ and t ₂ are the duration of the positive and the negative period of the current flow through the lamp, while the separation capacitor is recharged until the currents become equal due to a change in the voltage difference applied during the positive and negative period of the current flow through the lamp, i.e. the voltage form on the lamp becomes asymmetrical, which leads to even more heating of a warmer electrode, as well as to magnetization of the inductor and failure of the elements of the half-bridge converter. To eliminate this phenomenon, the average voltage feedback on the isolation capacitor was introduced, which establishes the ratio between the duration of the positive and negative periods of the current flowing through the lamp t ₁ and t ₂ , under which the condition:

t ₁ · I ₁ = t ₂ · I ₂

In this case, the amplitude of the applied voltage to the lamp in both phases of the half-bridge converter will be the same. As the lamp heats up, the temperature becomes equal, and the described phenomenon becomes hardly noticeable even with the vertical orientation of the lamp. Nevertheless, the mechanism for adjusting the duty cycle of the output signal of the generator continues to work even after the lamp reaches the operating mode.

During the heating of the lamp, the operating frequency of the generator is regulated so that the lamp current remains at a constant level. Frequency adjustment is carried out through the feedback circuit of the lamp current sensor.

2. The operating mode.

From the warm-up mode, the lamp smoothly switches to the operating mode, in which the current and voltage on the lamp correspond to the nominal values. In the case of lamp aging and mirroring, the voltage on the lamp increases at constant current, and the logic unit of the power control device determines that the lamp has reached the end of its life, and the voltage is maintained at 105% of the nominal value to eliminate emergency operation of the lamp.

Also, the logical unit of the power control device incorporates a timer for calculating the lamp operating time for failure, which provides comprehensive information about the state of the lamp, the ability to quickly repair or replace the exhausted lamps and, as a result, significantly reduce power consumption by preventing the lamp from working in non-optimized modes.

3. Power adjustment and diagnostics of lamp operation modes.

If you use a modem of a communication line over network wires or another modem (for example, an RS-485 protocol modem), a power control device with an integrated logic unit allows you to:

- adjust the lamp power in the range from 55 to 100% of the rated power;

- get information about the condition of the lamp in the form of “working - faulty”;

- receive data on lamp hours in hours.

Thus, the above implementation of intelligent electronic ballast provides:

- stabilization of the starting current at a level of not more than 110% of the nominal operating;

- limitation of the power supplied to the lamp at the nominal operating level;

- stabilization of lamp operating conditions during the warm-up period in order to eliminate uneven heating of the electrodes;

- control of the mode of re-ignition of the lamp;

- improving the spectral characteristics of radiated interference;

- unambiguous control of the operating modes of the lamp and fixtures based on it both in group control mode and in personal addressing mode;

- calculation of the actual operating time of the lamp;

- providing a remote diagnostic mode;

- providing an automated calibration and tuning mode.

The technical result achieved by using the proposed device is:

- in increasing the lamp life by 20-30%;

- reduction of operating costs, including electricity costs, by 15-20%;

- providing remote diagnostics, automated calibration and tuning of electronic ballast and lamp.

Information sources

1. Ballasts - the very heart of the lamp. - "Electrotechnical market", No. 6 (24), November-December 2008, p.58-5.

2. Energy-saving technologies in lighting. - "Electrotechnical market", No. 1 (25), January-April 2009, S.80-81.

3. RF patent, IPC Н05В 41/28, No. 2,275,760 dated November 14, 2003.

4. GOST R 51317.3.2-99 (IEC 61000-3-2-95). STATE STANDARD OF THE RUSSIAN FEDERATION "Compatibility of technical means electromagnetic emission of harmonic current components by technical means with a current consumption of no more than 16 A (in one phase)." Standards and test methods. - IPK "Publishing house of standards", 2000, p.1-25.

5. Panfilov D.I., Polyakov V.D., Polyakov Yu.D., Baryshnikov A.N. "Energy-saving electronic ballast for arc sodium lamps" - "Lighting", No. 6, 1999, S. 7-10 - prototype.

6. "High voltage greenline power factor controller". - "Motorolla", 1996, c.l6.

7. IEC 555-2; 1982. Disturbances in supply systems caused by hausehold appliances and similar electrical equipment. - Part 2: Harmonics (Amendment # 2; 1988).

Claims (4)

1. Intelligent electronic ballast for high-pressure discharge lamps, comprising a noise suppression filter in series, an overvoltage protection device, a rectifier, a power factor corrector, a half-bridge converter with an integrated variable frequency generator, the input of which is connected to the output of the power control device, and connected to the output in series primary winding of the choke-transformer, isolation capacitor and lamp, moreover, to the primary winding of the choke-trans a formatter is connected to a pulse ignition device, characterized in that a logic unit is additionally introduced into the power control device, a lamp current sensor connected in series with the lamp, an input low-pass filter is connected to the common point of the inductor transformer and isolation capacitor, the output of which is connected to the input of the variable generator frequency and with one of the inputs of the power control device, an input voltage detector is connected to a common point of the isolation capacitor and lamp, the output to connected to the input of the variable frequency generator and one of the inputs of the power control device, and also introduced a lamp current detector, the input of which is connected to the lamp current sensor, and the output to the input of the variable frequency generator and one of the inputs of the power control device, the output of the rectifier and the output of the power factor corrector is connected to the input of the power control device, one of the outputs of the power control device is connected to the input of the pulse ignition device, the output of which is connected to the secondary th winding of the inductor-transformer, and the second output of the power control device is connected to the input of the variable frequency generator. 2. The intelligent electronic ballast for high-pressure discharge lamps according to claim 1, characterized in that a bidirectional communication modem is introduced via network wires, one input-output of which is connected to the output of the noise suppression filter, and the other input-output is connected to the input of the power control device. 3. The intelligent electronic ballast for high-pressure discharge lamps according to claim 1, characterized in that a bi-directional communication radio modem is introduced, the input-output of which is connected to the power control device. 4. The intelligent electronic ballast for high-pressure discharge lamps according to claim 1, characterized in that a bi-directional modem of a dedicated communication line is introduced, one input-output of which is connected to a power control device, and the other input-output to a dedicated communication line.

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