JPH01217887A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To improve a power factor by connecting in series a simulated capacitor circuit provided with a property of a phase advancing current to the impressed AC voltage to an AC power supply and a discharge lamp. CONSTITUTION:An AC power supply 1, a discharge lamp 2 and a simulated capacitor circuit 3 are provided being connected serially. The simulated capacitor circuit 3 is provided with a property of flowing an advancing phase current to the impressed AC voltage, while being provided with four transistors Q1 to Q4 as semiconductor switching elements controlling charge and discharge of this capacitor C being connected to the main capacitor C in a bridge form, and a single chock L connected between a connection middle point of the transistors Q1, Q2 and a discharge lamp 2. Thereby, a point of a power factor to power supply can be cancelled and corrected while improving the power factor, for example, by using it in the form of combining with such in the simulated inductor circuit system, or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a discharge lamp lighting device suitable for lighting a discharge lamp, particularly a high-intensity discharge lamp.

Conventional technology Generally speaking, the main function of a discharge lamp lighting device is "current limiting".
In other words, from a different perspective, it can be said to be the exchange of reactive power.

Handling reactive power requires temporary energy storage means.

In this regard, conventional discharge lamp lighting devices of this type connect an AC power supply, a discharge lamp, a phase control circuit, and an inductance element for energy storage in series, and conduct current through the inductance element using the phase control circuit. The current flowing through the discharge lamp is converted into a direct current, and the current value flowing through the discharge lamp is controlled via this inductance element, so that the discharge lamp is supplied with a current that is close to a rectangular wave and has a controlled average current value. This is known from Japanese Patent Application Laid-Open No. 57-72296.

In other words, flicker is reduced by bringing the current supplied to the discharge lamp closer to a rectangular wave, and the discharge lamp is dimmed by controlling the lamp current (average value).

However, in a discharge lamp lighting device, in order to reduce flicker, it is necessary to make the inductor as an inductance element larger, and it is necessary to make the inductor as an inductance element larger. are contradictory.

Therefore, in order to satisfy these conflicting demands, the present applicant proposed a structure in which the inductance element is constructed of a simulated inductor (slow phase current limiting circuit) as published in Japanese Patent Application Laid-open No. 181491/1983. has been done.

However, in the case of using the simulated inductor circuit method disclosed in the publication, the power factor of the power source is low, and there is a need to improve the power factor.

Means for Solving the Problems The method includes an AC power source, a discharge lamp, a main capacitor for energy storage, and a semiconductor switching element for controlling charging and discharging of the main capacitor. Connect in series with a simulated capacitor circuit that has the property of flowing.

Since the lamp current supplied to the working discharge lamp is based on the simulated capacitor circuit, it becomes a phase leading current with respect to the applied AC voltage. As a result, when used in combination with, for example, a simulated inductor circuit system, it is possible to compensate for the low power factor of the power source and improve the power factor.

Example An embodiment of the present invention will be described based on the drawings.

First, an AC power source 1, a discharge lamp 2, and a simulated capacitor circuit (phase advance formation current circuit) 3 are connected in series. This simulated capacitor circuit 3
Although the circuit configuration is similar to the simulated inductor circuit, its operation is different, and it has the property of flowing a phase-advanced current with respect to the applied AC voltage from the AC power supply l, and is an energy storage means. a main capacitor C as a main capacitor C, four transistors Q, -Q as semiconductor switching elements that are bridge-connected to control charging and discharging of this capacitor C, and four diodes D1 to D4 for rectification.
and a single choke L (of small inductance for high frequency smoothing) connected between the connection midpoint of the transistors Q, Q, and the discharge lamp 2. Here, the transistors Q, -Q.

are turned on/off or switched under individual operation control by a drive control circuit (not shown).

In such a configuration, the operation of this embodiment, particularly the operation of the simulated capacitor circuit 3, will be explained with reference to the operation waveform diagram of FIG. 2 and the circuit diagrams of FIGS. 3 and 4. Here, the terminals at both ends of the simulated capacitor circuit 3 are designated as A and B as shown in FIG. First, the transistor Q is activated at a predetermined phase when the power supply voltage Vin of the AC power supply 1 is positive.

~Q is turned off, but only transistor Q is operated for switching. At this time, the simulated capacitor circuit 3 of (3) becomes isometrically as shown in FIG. 4(a). The switching duty ratio of the transistor Q4 at this time is as shown in FIG. 2(e), and the voltage between terminals A and B of the simulated capacitor circuit 3 is
That is, the charging voltage of the main capacitor C is as shown in Fig. 2 (b) during the period ■.
) increases as shown. That is, in the equivalent circuit of Fig. 4(a), since transistor Q4 is on, current flows to the transistor 4 side, but as its conduction state decreases over time, the current flowing to the main capacitor C side increases. be.

Next, in the positive state of the power supply voltage Vin, when the period shown in (3) is reached, the transistors Q, , Q.

While the pair of transistors Q and Q are both turned off,
is turned on, and the switching of transistor Q is controlled. The switching duty ratio at this time is as shown in FIG. 2(d).

Also, the equivalent circuit of the simulated capacitor circuit 3 at this time is as shown in FIG. 4(b), with transistors Q,
Since the charging voltage of the main capacitor C is discharged superimposed on the switching operation of the terminal A.

The B threshold voltage VAB becomes a large voltage as shown in the waveform of section (3) in FIG. 2(b). In this way, the polarity of the lamp current IL for the discharge lamp 2 is reversed between sections 2 and 3, so it is momentarily turned off, but it is immediately switched off by the capacitor stored energy superimposed on the AC power supply 1, and the lamp current IL is turned off. The lamp voltage settles down to a more or less constant level. In other words,
In section (3), the main capacitor C is discharged.

Then, the charge in the main capacitor C is discharged, and the terminal A
, the voltage between B becomes O to 8 B, and when it reaches the interval ■, the interval ■
For the state of , transistor Q is also turned off, and switching of only transistor Q is controlled. The equivalent circuit of simulated capacitor circuit 3 at this time is shown in Figure 4 (
C). That is, the polarity is reversed from that shown in FIG. 4(a). Points other than polarity are the same as in the case of interval ■. Then, when the switching control of the transistor Q is completed and the next period (3) begins, the transistor Q is turned on.

is in a state where switching is controlled. The equivalent circuit of simulated capacitor circuit 3 at this time is shown in Figure 4(d).
It becomes as shown in. That is, the polarity is reversed from that shown in FIG. 4(b), and the discharge operation of the charging energy stored in the main capacitor C is performed with the reverse polarity. Thereafter, the operations shown in sections ■ to ■ are repeated in the same way, and the discharge lamp 2
As shown in FIG. 2, the lamp current IL flows in a stable rectangular wave state.

By controlling using the simulated capacitor circuit 3 in this manner, the discharge lamp 2 can be lit with a rectangular wave lamp current with less flicker. On this occasion,
The winding component (coil) requires only one single choke L with small inductance for high-frequency smoothing, and the electronic ballast can be made small, lightweight, and inexpensive.

In addition, as the simulated capacitor circuit 3, the fifth
As shown in the figure, transistors Q,,Q.

It is also possible to omit the diodes D, D4, and simplify the two-stone system in which the main capacitor C is divided into two parts C, and C, and a single choke is connected to the midpoint of the connection. .

Furthermore, by combining the simulated capacitor circuit of this embodiment with the simulated inductor circuit method described above, a lighting device with a higher power factor can be obtained.

Effects of the Invention As described above, the present invention provides a simulated capacitor circuit that has a property of flowing a phase-advanced current in response to an applied AC voltage from an AC power source and is connected in series with an AC power source and a discharge lamp. By appropriately combining it with a simulated inductor circuit system, etc., it is possible to offset and correct the low power factor points of both, and to control the lighting of the discharge lamp in a high power factor state with respect to the AC power supply. Since it is a simulated capacitor circuit system, the number of winding parts can be reduced.
It can be made small, lightweight, and inexpensive as a lighting device or an electronic ballast.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a circuit diagram, FIG. 2 is a timing chart showing operating waveforms of each part, and FIG. 3 is a circuit diagram of a simulated capacitor circuit.
FIG. 4 is an equivalent circuit diagram of each section, and FIG. 5 is a circuit diagram showing a modified example. 1... AC power supply, 2... Discharge lamp, 3... Simulated capacitor circuit, C... Main capacitor, Q1
~Q4...Semiconductor switching element, % J Figure J, Figure u

Claims (1)

[Claims] A simulated lamp that includes an AC power supply, a discharge lamp, a main capacitor for energy storage, and a semiconductor switching element that controls charging and discharging of the main capacitor, and has a property of flowing a phase-advanced current with respect to the AC voltage applied by the AC power supply. A discharge lamp lighting device characterized by connecting a capacitor circuit in series.