JP2001326087A - Fluorescent lamp inverter control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent increase of harmonic current distortion and not to make a gate trigger mode of triac become a mode of undesirable polarity. SOLUTION: The harmonic current distortion of a fluorescent lamp inverter 6 as a load is lowered by an active filter. Although it is not illustrated, as it is commonly known, the fluorescent lamp inverter 6 has an active filter composed of a chopper circuit at its input side, and an inverter circuit is driven through the active filter, and the fluorescent lamp is lighted by the output converted into high frequency. For the fluorescent lamp inverter control circuit, at the construction of on/off controlling the AC power source 1 of the fluorescent lamp inverter 6 by the triac 3, as a gate control power source circuit 7 of the triac 3 makes the triac 3 practically operate continuously in the state of turned on, negative side output voltage (-) is continuously impressed to a gate G of the triac.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent lamp inverter control circuit having a configuration in which the AC power supply of a fluorescent lamp inverter whose harmonic current distortion rate is reduced by an active filter is turned on / off by a triac.

[0002]

2. Description of the Related Art As shown in FIG. 4, when a load 2 having an AC power supply 1 as an input is ON / OFF controlled by a triac 3, a gate trigger control circuit of the triac 3 includes a resistor between the AC power supply 1 and the gate G. Generally, a circuit is connected between the switch 4 and the switch element 5, and after the triac 3 is turned on, the triac 3 is kept on by the holding current of the triac 3 until the zero cross of the AC power supply 1.

[0003]

However, when the load 2 is a fluorescent lamp inverter in which the harmonic current distortion rate is reduced by the active filter, the chopper circuit constituting the active filter near the zero cross of the AC power supply 1 is stopped. When the current in this section is less than or close to the holding current of the triac 3, the current falls below the holding current due to ringing or the like when the current tries to settle to the current in the pause section. , Triac 3 is turned off. When the triac 3 is turned off, a trigger is applied to the gate G again, and the triac 3 repeats ON / OFF, so that the main current (between T1 and T2) of the triac 3 has a waveform as shown in FIG. The current distortion rate increases. An object of the present invention is to solve the above problem and to prevent an increase in the harmonic current distortion rate, and not to set the triac gate trigger mode to an undesired polarity mode.

[0004]

Means for solving the problems are as described in the claims.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described. However, this is merely an exemplary embodiment adopted based on the present invention, and the present invention will be described based on matters unique to the embodiment. Therefore, the technical scope of the present invention should be determined based on the matters stated in the claims and matters substantially equivalent to the matters.

An embodiment of the present invention is shown in FIGS. The fluorescent lamp inverter 6 serving as a load has a harmonic current distortion rate reduced by an active filter. Although the internal circuit is not shown, as is well known,
Has an active filter composed of a chopper circuit on its input side, drives an inverter circuit via the active filter, and lights a fluorescent lamp with an output converted to a high frequency by the inverter circuit. In the fluorescent lamp inverter control circuit according to the present embodiment, in the configuration in which the AC power supply 1 of the fluorescent lamp inverter 6 is ON / OFF controlled by the triac 3, the gate control power supply circuit 7 of the triac 3 includes the triac 3 ON substantially continuously
In order to make the gate G have a negative output voltage (-)
Is applied continuously.

In FIG. 1, a gate control power supply circuit 7
Rectifies the AC power 1 through the insulating transformer 8
The zero-side positive output voltage (+) of the DC power supply is connected to the T1 side of the triac 3. To turn on the triac 3, turn on the transistor Q at the base of the transistor Q.
A signal to cause the current to flow through the gate G.

In FIG. 2 and FIG. 3, a gate control power supply circuit 7 outputs a positive output voltage (+) of a non-insulated switching DC power supply that performs half-wave rectification 11 on the AC power supply 1 and then performs switching 12 and smoothing 13. Connected to T1 side of TRIAC 3. To turn on the triac 3, the switch element Q is turned on and a current flows through the gate G.

As in these embodiments, when the fluorescent lamp inverter 6 is operated, the triac 3 is turned on. In this case, a current always flows through the gate G of the triac 3, so that the triac 3 is turned on. Even if the main current (between T1 and T2) falls below the holding current, the triac 3 can be prevented from being turned off, thereby preventing the main current waveform from being distorted. Can be prevented from increasing.

Further, the gate trigger mode of the triac 3 is not set to a mode having an undesirable polarity. The undesired polarity mode is a mode in which the gate G becomes + when T1 = + and T2 = − of the triac 3, but the negative output voltage (−) is applied to the gate G as described above. Therefore, the mode does not have an undesirable polarity.

In FIGS. 2 and 3, since the gate control power supply circuit 7 can be a non-insulated switching DC power supply, there is an advantage that an expensive and electrically insulating transmission device such as a transformer or a photocoupler is not required. .

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the present invention.

FIG. 3 is a circuit diagram showing still another embodiment of the present invention.

FIG. 4 is a conventional typical circuit diagram.

FIG. 5 is a conventional power supply current waveform diagram.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 3 Triac 6 Fluorescent lamp inverter 7 Gate control power supply circuit 8 Insulation transformer 9 Rectifier 10 Smoothing capacitor 11 Rectifier 12 Switching element 13 Smoothing capacitor

Claims (3)

[Claims] In a configuration in which an AC power supply of a fluorescent lamp inverter whose harmonic current distortion rate is reduced by an active filter is turned on / off by a triac, a gate control power supply circuit of the triac makes the triac substantially continuous. A fluorescent lamp inverter control circuit that continuously applies a negative output voltage to its gate G to turn it on. 2. The fluorescent lamp inverter control circuit according to claim 1, wherein the gate control power supply circuit connects a positive output voltage of a DC power supply obtained by rectifying and smoothing the AC power supply via an insulating transformer to a T1 side of the triac. 3. The fluorescent lamp inverter control according to claim 1, wherein the gate control power supply circuit connects the positive side output voltage of a non-insulated switching DC power supply that rectifies and then switches and smoothes the AC power supply to the T1 side of the triac. circuit.