RU128340U1 - ELECTRON LOAD FOR HIGH FREQUENCY BALLASTS FOR LUMINESCENT LAMPS - Google Patents

Abstract

An electronic load of a high-frequency ballast for fluorescent lamps, comprising an electronic DC load with energy recovery to the power supply network, characterized in that the ballast is equipped with a matching device that contains a high-frequency voltage transformer with two windings, a primary and a secondary, a rectifier and a capacitor, and the output of the ballast is connected to the primary winding of the voltage transformer, the secondary winding is connected to the rectifier, and the rectifier output is connected to the capacitor connected to the electronic a constant DC load having an input characteristic of a parallel voltage regulator, while an arbitrary number of outputs of matching devices with ballasts connected to them are connected to the input of one electronic DC load with energy recovery, and all ballasts are connected to the power supply network in parallel, and the maximum number of connected devices is determined by the power of the electronic DC load.

Description

The utility model relates to electrical engineering and can be used in stands for testing high-frequency ballasts for fluorescent lamps.

In well-known stands for long-term testing of ballast of fluorescent lamps for reliability, standard fluorescent lamps are used as the load, for the supply of which the ballast is intended. With large-scale and mass production of ballasts, for such tests it is necessary to go for significant energy costs and a large number of fluorescent lamps.

Known electronic AC loads that are designed to work as a load when testing, tuning and adjusting power supplies, amplifiers, sound-reproducing equipment and other radio devices that could be used instead of fluorescent lamps when testing ballasts, for example, ATN- programmable electronic load 8365, described on the Aktakom website www.aktakom.ru/kio/index.php?ELEMENT_ID=38865

Such loads are very expensive and do not provide energy return from the outputs of the ballasts to their supply network

Powerful DC electronic loads are also known, for example, EA-ELR 9000 3.5 KW - 10 KW series loads manufactured by EA-Electro-Automatic GmbH, with energy recovery with its return to the power supply, produced for testing power supplies and converters (converters) DC. The technical solution closest to the one proposed is described in the article by Carlos Roncero ... “Controllable electronic load with energy recycling capability”, Przeglad Electrotechniczny (Electrical Review), LSSN 0033-2097, R. 87 No. 4/2011

The disadvantage of this circuit is the inability to directly connect the RF outputs of the ballasts to the input of the electronic load, which performs the function of energy recovery in the power network.

The technical problem that is solved by the proposed utility model is the coordination of a large number of RF outputs of simultaneously operating ballasts with the input of a direct current electronic load with energy recovery into the power supply network by creating a matching device that is equivalent in its load characteristics to the characteristics of a fluorescent lamp in operating mode, and the output is matched in parameters with the input of the DC electronic load.

The technical result consists in the fact that the proposed technical solution makes it possible to supply power to the tested ballasts, at which the ballast provides full output power, consuming energy, up to 90% of which is returned from the output to the input via the power network, which allows 7-10 times reduce the cost of electricity for testing in large-scale and mass production of ballasts for fluorescent lamps. In addition, the consumption of fluorescent lamps for testing is excluded.

The indicated technical result is achieved by the fact that each ballast is equipped with a matching device, which contains a high-frequency voltage transformer with two windings, a primary and a secondary, a rectifier and a capacitor; moreover, the ballast output is connected to the primary winding of the voltage transformer, the secondary winding is connected to the rectifier, and the rectifier output is to a capacitor connected to an electronic DC load having an input characteristic of a parallel voltage regulator. At the same time, an arbitrary number of outputs of matching devices with ballasts connected to them are connected in parallel to the input of one electronic DC load with energy recovery, and all ballasts are connected to the power supply network in parallel, and the maximum number of connected devices is determined by the power of the DC electronic load.

The description of the utility model is illustrated by drawings, where Fig. 1 shows a diagram of the proposed electronic load, and the principle of its operation is illustrated by Figs. 2 ... Fig. 4. Figure 2, shows a diagram of the load of the ballast with a fluorescent lamp, Figure 3 is a diagram of the load on the device matching with the electronic load of direct current, and Figure 4 shows the timing diagrams of the current explaining the equivalence of loads ..

The proposed electronic load for K ballasts 1 (1-1 ... 1-K), contains matching devices 2 (2-1 ... 2-K) and electronic load 3 with energy recovery in the power network. The outputs of the ballasts are connected to the inputs of the matching devices 2, including a high-frequency voltage transformer 4, a rectifier 5 (for example, a diode bridge) and a capacitor 6. The outputs of all matching devices are connected in parallel and connected to the input of the electronic load 3, which has an input characteristic of a parallel voltage regulator.

The legitimacy of replacing fluorescent lamps with such a load and the principles for calculating the parameters of the matching device are explained as follows:

In all electronic ballasts, an RF choke is located at the output, limiting the lamp current. The current-voltage characteristics (CVC) of the lamp in the operating mode are non-linear, but when the lamp is supplied with RF current (at frequencies above 1 kHz), the lamp can be considered an active load at any time. The lamp circuit shown in Fig. 2, at an arbitrary moment of the RF power supply period, can be represented by the inductance L of the inductor L and the active resistance r (i) connected to each other at a square voltage from the RF converter. Figure 3 shows the connection diagram of the same ballast to the proposed matching device.

The voltage Uvch on the lamp circuit formed by the series-connected lamp and inductor in the steady-state operating mode has a rectangular shape, and its amplitude is equal to half the supply voltage Epit. In this case, the capacitor C is charged to half the supply voltage Epit, and when the upper switch is turned on, the current in the circuit rises, and when the lower switch is turned on, it drops. Timing diagrams explaining this process are shown in FIG. 4 (RF voltage UHF and RF current UHF, lamp. Curves).

The slew rate of the current in the circuit is limited by the inductor and is determined by the formula

one.

Where i is the instantaneous current value;

t is time

r (i) is the instantaneous value of the lamp resistance, depending on the current;

L is the inductance of the inductor.

The solution of this equation, to a first approximation (r = const), will give the exponent (see Fig. 4). The curve corresponding to a more accurate representation of r (i) will be close to this exponent. In the initial section, the curve has a slope of φ1, and in the final, before switching keys, φ2. In Fig. 4, from the beginning to the end of the half-cycle of the supply current of the lamp circuit, the slope of the current curve decreases by about 7 times (φ1 = 7φ2), which means a 7-fold decrease in the voltage across the inductor in the same interval. At the same time, the actual value of the current can be, depending on the type of r (i), only 20-30% more than the rms value of the saw formed by connecting the current peaks at the moments of switching the ballast keys.

Figure 4. Timing charts.

If you load the ballast on a symmetrical voltage limiter U _o , then the expression for the rate of change of the circuit current will take the form

2

от нуля до

, и установить его таким образом, чтобы действующее значение тока цепи точно соответствовало действующему значению тока лампы.By changing U _out , you can change the slope

from zero to

, and set it so that the effective value of the circuit current exactly matches the actual value of the lamp current.

In order to ensure energy recovery in the network, the function of a symmetrical voltage limiter, which also provides galvanic isolation of the input and output, is performed by the device (Fig. 3) containing a voltage transformer 4, a rectifier 5 and a capacitor 6. The limiting voltage is then set by the electronic load with the input characteristic of a parallel voltage regulator, changing this voltage from U1 to U3 (Figure 4), you can change the load of the ballast by setting the rms current value both less (U3) and more (U1) of the nominal nogo value (U2) .. In the parallel connection of several outputs of such devices mode all connected to them automatically set to the same ballast.

The primary winding of the voltage transformer must have an inductance many times higher than the inductance of the inductor L. Then the voltage at the winding at which the current begins to rise (at a given speed) will be determined only by the voltage specified by the electronic load.

The claimed device works as follows: when power is supplied from the network to the ballasts, they turn on immediately in the operating mode, without the lamp ignition mode. The network energy is converted into the RF energy of the lamps and is supplied from the outputs of the ballasts 1-1 ... 1-K to the inputs of the matching devices 2-1 ... 2-K, the outputs of which are connected in parallel and connected to an electronic load 3, which maintains a stable input voltage, taking direct current energy from its input and converting it into alternating current energy with a frequency of 50 Hz, phased with the power supply network. This energy from the output of the electronic load is returned back to the power supply.

As a result of testing the working layout of the proposed device, it was found that to ensure the rated operating modes of the tested ballasts in current and converted power, the total energy consumption is reduced by 7-10 times, which can significantly reduce the cost of long-term tests (for example, reliability). The most effective application of the utility model in serial and mass production of ballasts.

Claims (1)

An electronic load of a high-frequency ballast for fluorescent lamps, comprising an electronic DC load with energy recovery to the power supply network, characterized in that the ballast is equipped with a matching device that contains a high-frequency voltage transformer with two windings, a primary and a secondary, a rectifier and a capacitor, and the output of the ballast is connected to the primary winding of the voltage transformer, the secondary winding is connected to the rectifier, and the output of the rectifier is connected to the capacitor connected to the electronic a constant DC load having an input characteristic of a parallel voltage regulator, while an arbitrary number of outputs of matching devices with ballasts connected to them are connected to the input of one electronic DC load with energy recovery, and all ballasts are connected to the power supply network in parallel, and the maximum number of connected devices is determined by the power of the electronic DC load.

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