JP2008099345A - Inverter, fluorescent lamp appliance, and illumination appliance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inverter capable of preventing a surge current from being applied to FETs of an N-channel and a P-channel when an fluorescent lamp is turned on. <P>SOLUTION: The inverter includes a smoothing capacitor 5 for smoothing an output of a full-wave rectification circuit 4; the FETs 6, 7 of N- and P-channels provided between output ends of the smoothing capacitor 5 and connected in serial; a ballast coil 8 connected to a connection point between the FET 6 of N-channel and the FET 7 of P-channel; a secondary winding 8b electromagnetically connected to the ballast coil 8; an oscillation circuit consisting of an inductor 15 and a capacitor 16 provided between both the ends of the secondary winding 8b; and a serial circuit consisting of a capacitor 17 and a resistor 21 provided between a connection point of the inductor 15 and the capacitor 16, and gate sides of the FETs 6, 7 of N-, P-channels. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an inverter device for lighting a fluorescent lamp, a fluorescent lamp device including the inverter device, and an illumination device having the fluorescent lamp device.

  Conventionally, a half-bridge inverter in which an N-channel FET and a P-channel FET are connected in series is generally used as an inverter device built in a bulb-type fluorescent lamp (for example, see Patent Document 1).

Japanese Patent No. 3413754 (page 3-5, Fig. 1-2)

  However, in the conventional inverter device described above, the phase of the current flowing through the N-channel FET and the P-channel FET is advanced when the power is turned on, that is, at the start of lighting of the fluorescent lamp, compared with the phase of the voltage. Therefore, a surge current flows. This is due to the fact that the current phase advances due to the resonant operation of the ballast coil and the starting capacitor. A pulsed current flows from the drain to the source of the FET at the moment when the FET is turned on by so-called hard switching. This pulsed current is a charge / discharge current of a snubber capacitor connected between the drain and source of the FET and a drain-source capacitance, and the snubber capacitor is an essential component for protecting the FET. The resonance operation is necessary for starting the discharge of the fluorescent lamp, and a high voltage is applied to the fluorescent lamp by this resonance operation.

  For example, as shown in FIG. 9, at the timing when the P-channel FET is turned on, a current having a steep pulse waveform as shown in (1) flows from the drain to the source, and between the drain and source shown in (2). The product of the voltage is a power waveform (loss) as shown in (3). On the other hand, the voltage and current of the N-channel FET are reversed in polarity from that of the P-channel, and similarly, a current having a pulsed waveform flows from the drain to the source. This pulsed current, that is, surge current, is superimposed on the power supply line, and as a noise, it may affect the lighting device or other equipment incorporating the inverter device. Further, these surge currents cause losses in the N-channel and P-channel FETs, and it is necessary to select an FET that can tolerate this loss.

  The present invention has been made in order to solve the above-described problems, and suppresses the influence of noise by preventing surge current from flowing at the start of lighting of a fluorescent lamp. It aims at providing the fluorescent lamp apparatus which has an inverter apparatus, and an illuminating device provided with the fluorescent lamp apparatus.

  An inverter device according to the present invention includes a full-wave rectifier circuit, a smoothing capacitor for smoothing the output of the full-wave rectifier circuit, and an N-channel and P-channel switching element connected in series between the output terminals of the smoothing capacitor. A ballast coil connected to the connection point of the N-channel switching element and the P-channel switching element, a secondary winding magnetically connected to the ballast coil, and both ends of the secondary winding. A resonance circuit is provided, and a resonance voltage generated in the resonance circuit is applied to each of the N-channel and P-channel switching elements via a series circuit of a resistor and a capacitor so as to be turned on and off alternately.

  In the present invention, since the resonance voltage applied to each switching element of the N channel and the P channel is made to pass through a series circuit of a resistor and a capacitor, the N channel has a frequency higher than the resonance frequency determined by the ballast coil and the starting capacitor. In addition, the switching elements of the P channel and the P channel can be turned on and off alternately. For this reason, the surge current generated at the start of lighting of the fluorescent lamp does not flow to each switching element, and the influence of this noise on the apparatus and other equipment is eliminated, and an inverter apparatus with a small loss of the switching element can be provided.

FIG. 1 is a circuit diagram of an inverter device showing an embodiment of the present invention.
A full-wave rectification circuit 4 shown in the figure performs full-wave rectification on the voltage of the commercial power supply 1 applied via an LC filter circuit composed of a capacitor 2 and an inductor 3. The smoothing capacitor 5 is connected between the output terminals of the full-wave rectifier circuit 4 and smoothes the DC voltage that has been full-wave rectified by the full-wave rectifier circuit 4. For example, the N-channel FET 6 and the P-channel FET 7 which are switching elements are connected to each other on the source side and on the gate side, the drain of the N-channel FET 6 is on the high potential side of the power supply voltage, and the drain of the P-channel FET 6 is the power supply voltage. Connected to the low potential side.

  The ballast coil 8 includes a primary winding 8a having one end connected to the source side of the P-channel FET 6 and the other end connected to the DC cut capacitor 9, and a secondary winding 8b magnetically connected to the primary winding 8a. And. The starting capacitor 11 has one end connected to the DC cut capacitor 9 via the filament 10a of the fluorescent lamp 10 connected to the apparatus, and the other end connected to the drain side of the P-channel FET 6 via the filament 10b of the fluorescent lamp 10. Has been. A resonance circuit is formed by the series capacitance of the primary winding 8 a of the ballast coil 8 and the DC cut capacitor 9 and the starting capacitor 11 described above. The capacities of the DC cut capacitor 9 and the start capacitor 11 are in a relationship of DC cut capacitor 9> start capacitor 11, and the start capacitor 11 mainly acts as a resonance circuit.

  The resistor 12 (first resistor) connected in parallel with the snubber capacitor 20 interposed between the drain and the source of the N-channel FET 6, the secondary winding 8 b of the ballast coil 8, the N-channel FET 6 and the P-channel FET 7 in common A starter circuit is configured by the resistor 13 (second resistor) inserted between the gate and the resistor 14 (third resistor) connected in parallel between the gate and drain of the P-channel FET 7 to form an N channel. And activate the FETs 6 and 7 of the P channel. The inductor 15 and the capacitor 16 connected in series between both ends of the secondary winding 8b of the ballast coil 8 constitute a resonance circuit.

  A series circuit of the capacitor 17 and the resistor 21 is inserted between the connection point of the inductor 15 and the capacitor 16 of the above-described resonance circuit and the common gate of the N-channel and P-channel FETs 6 and 7. This series circuit of the capacitor 17 and the resistor 21 inputs a voltage induced in the secondary winding 8 b of the ballast coil 8 to the common gate of the N-channel FET 6 and the P-channel FET 7 as a gate drive signal. Zener diodes 18 and 19 are connected in series between the gate side of the N-channel FET 6 and the source side of the P-channel FET 7, and are provided to protect the gates of the N-channel FET 6 and the P-channel FET 7.

Next, the operation of the inverter device of this embodiment will be described with reference to FIGS. FIG. 2 is a graph showing the oscillation frequency at the time of lighting with the capacitance value of the capacitor 16 as a parameter, FIG. 3 is a waveform diagram of the voltage and current of the N-channel FET during lighting of the fluorescent lamp, and FIG. FIG. 5 is a graph showing the oscillation frequency at the time of starting with the capacitance value of the capacitor 16 as a parameter, and FIG. 6 is the current and voltage of the P-channel FET at the start of lighting of the fluorescent lamp. FIG. 6 is a waveform diagram of electric power. This embodiment will be described using the following circuit constants.
Inductance of primary winding 8a = 0.8mH
Inductance of secondary winding 8b = 3.1 μH
Capacitance of starting capacitor 11 = 0.0055 μF
Capacitance of DC cut capacitor 9 = 0.1 μH
Inductance of inductor 15 = 1 mH
Capacitor 17 capacity = 0.1 μH

When the commercial power source 1 is turned on in the apparatus, the full-wave rectifier circuit 4 full-wave rectifies the AC voltage of the commercial power source 1 and the smoothing capacitor 5 smoothes. Then, a voltage is applied to the gate of the P-channel FET 7 through the resistor 12, the secondary winding 8b of the ballast coil 8, the resistor 13, and the resistor 14, and the P-channel FET 7 is turned on, and the primary winding 8a of the ballast coil 8 is turned on. Through this, a voltage is applied to the fluorescent lamp 10. At this time, a voltage is induced in the secondary winding 8 b of the ballast coil 8, and the inductor 15 and the capacitor 16 resonate. The resonance voltage passes through the capacitor 17 and the resistor 20, and the gates of the N-channel FET 6 and the P-channel FET 7. Are alternately applied to turn on and off (oscillate) the N-channel and P-channel FETs 6 and 7 alternately, and the fluorescent lamp 10 is turned on at high frequency.
The oscillation frequency of the inverter is set to 80 kHz from the voltage of the commercial power source 1, the current of the lamp 10 at the time of lighting, and the value of the inductance of the primary winding 8a. The oscillation frequency is determined by the resonance circuit of the ballast coil 8 and the starting capacitor 11, the turn ratio of the ballast coil, and the resonance circuit of the inductor 15 and the capacitor 16. For example, when the capacitance of the capacitor 16 is used as a parameter, the graph shown in FIG. Become. In FIG. 2, the graph (1) shows the frequency characteristics when the resistor 21 is 0Ω, that is, the oscillation frequency in the conventional circuit, and the graph (2) shows the frequency characteristics when the resistor 21 of 330Ω is connected in series with the capacitor 17. Thus, it can be seen that when the resistor 21 is connected in series with the capacitor 17, the oscillation frequency is increased even if the capacitor 16 has the same capacity. In the graph of FIG. 2, the resistance 21 is 330Ω and a frequency 10 kHz higher, and is proportional to the resistance value of the resistance 21 connected in series with the capacitor 17. From the graph of FIG. 2, when the oscillation frequency is set to 80 kHz, when the resistor 21 is 0Ω, the point becomes A, and the capacitance of the capacitor 16 becomes 0.0015 μF, and when the resistor 21 is 330Ω, the point becomes B. The capacity of 16 is adjusted to 0.002 μF.

  When the fluorescent lamp 10 is lit, the N-channel FET 6 generates the voltage shown in FIG. 3A between the drain and the source, and the current shown in FIG. 3B flows from the drain toward the source. Further, in the P-channel FET 7 in which the fluorescent lamp 10 is turned on, the voltage shown in FIG. 4A is generated between the drain and the source, and the current shown in FIG. 4B flows from the drain toward the source. Thus, during the lighting of the fluorescent lamp 10, the current is in a phase that is delayed with respect to the voltages of the FETs 6 and 7. In the conventional circuit, the resistor 21 is 0Ω, but operates at a delayed phase when it is lit, and when the resistor 21 is set to 330Ω, the current phase is further delayed, but there is no great difference in the delayed phase between the two. Both have no problems.

On the other hand, since the fluorescent lamp 10 is not lit when the power is turned on, that is, when lighting is started, the current flowing from the N-channel FET 6 and the P-channel FET 7 is caused by the series resonance of the primary winding 8a of the ballast coil 8 and the starting capacitor 11. Resonant current. The resonance current flowing in the primary winding 8a of the ballast coil 8 flows nearly five times as much as that during lighting, and the voltage induced in the secondary winding 8b also increases, passes through the resonance circuit of the inductor 15 and the capacitor 16, passes through the capacitor 17 and The signals are input to the gates of the N-channel FET 6 and the P-channel FET 7 through the series circuit of the resistor 21, respectively. At this time, the voltage applied to the gates of the N-channel FET 6 and the P-channel FET 7 by the resistor 21 is lowered, the time clipped by the Zener diodes 18 and 19 is shortened, and the on-time of the N-channel FET 6 and the P-channel FET 7 is the same. Therefore, the oscillation frequency becomes higher.
The graph of FIG. 5 is obtained by plotting the oscillation frequency at the time of starting with the capacitance of the capacitor 16 as a parameter. (1) shows the characteristic that the resistance 21 is 0Ω, and (2) shows the characteristic that the resistance 21 is 330Ω. When the resistance 21 is 0Ω, 0.0015 μF is connected to the capacitor 16 from the lighting frequency, and the oscillation frequency at this time is a point A and becomes 75.5 kHz. When the resistance 21 is 0Ω, the capacitor 16 is connected to 0.002 μF from the lighting frequency, and the oscillation frequency at this time is the point B and becomes 77.5 kHz.
On the other hand, the series resonance frequency (f) of the primary winding 8a (L) of the ballast coil 8 and the starting capacitor 11 (C) is calculated from the following formula and becomes 76 kHz.

このように、抵抗２１が０Ωの場合、共振周波数（ｆ）より低い周波数で発振するためＮチャネルＦＥＴ６とＰチャネルＦＥＴ７の電圧に対して電流が進みの位相で発振する。抵抗２１が３３０Ωの場合、共振周波数（ｆ）より高い周波数で発振するためＮチャネルＦＥＴ６とＰチャネルＦＥＴ７の電圧に対して電流が遅れの位相で発振する。

Thus, when the resistance 21 is 0Ω, the oscillation occurs at a frequency lower than the resonance frequency (f), so that the current oscillates in a phase in which the current advances with respect to the voltages of the N-channel FET 6 and the P-channel FET 7. When the resistance 21 is 330Ω, the current oscillates at a phase delayed with respect to the voltages of the N-channel FET 6 and the P-channel FET 7 because it oscillates at a frequency higher than the resonance frequency (f).

  As shown in FIG. 6, at the timing when the P-channel FET is turned on, a current as shown in (1) flows from the drain to the source, and the product of the drain-source voltage shown in (2) becomes (3). The power waveform (loss) is as shown. Although not shown, the N-channel FET 6 is applied with a voltage whose polarity is inverted between the drain and the source with respect to the voltage applied to the P-channel FET 7, and a current whose polarity is inverted flows from the drain to the source.

  As described above, the series resonance of the primary winding 8a of the ballast coil 8 and the starting capacitor 11 so as to delay the phase of the current flowing through the FETs 6 and 7 with respect to the voltage applied to the N-channel FET 6 and the P-channel FET 7 at the start of lighting. Since it oscillates at a frequency higher than the frequency, there is no steep pulse-like surge current compared to the current waveform shown in FIG. 9 (1) (see FIG. 6 (1)). 7 can be kept small, and an inverter device can be provided in which noise and other devices are not affected by noise.

In the above inverter device, it has been described that the N-channel FET 6 and the P-channel FET 7 are used as the switching elements. Instead, N-channel and P-channel IGBTs (Insulate Gate Bipola Transistors) may be used. .
In the inverter device, the snubber capacitor 20 is used in the snubber circuit for protecting the N-channel FET 6 and the P-channel FET 7. However, the snubber capacitor 20 may be replaced with a series circuit of a capacitor and a resistor. However, in this case, the loss of the snubber circuit increases and the efficiency of the inverter device decreases.

FIG. 7 is a sectional view showing a fluorescent lamp device provided with the inverter device according to the embodiment of the present invention.
A fluorescent lamp device 22 shown in the figure is a bulb-type fluorescent lamp provided with the inverter device described above. The cover 24 constituting the base of the bulb-type fluorescent lamp is formed of a heat-resistant synthetic resin such as PBT resin, and a substantially spherical globe 25 made of glass is fitted on one end thereof, and Edison is arranged on the outer periphery. A screw-type base 23 such as type E26 is attached. The fluorescent lamp 26 is formed in, for example, a spiral shape, one end of which is fixed to the partition plate 28, and is covered with the globe 25. The substrate 27 is housed in the base 23 and the circuit of the inverter device shown in FIG. 1 is mounted. The partition plate 28 described above is provided to separate the fluorescent lamp 26 and the substrate 27 in addition to fixing the fluorescent lamp 26.

  As described above, since the inverter device shown in FIG. 1 is built in the fluorescent lamp device 22 (bulb-shaped fluorescent lamp), noise generated at the start of lighting is eliminated. The effect on the equipment is gone.

Next, an illumination device using a bulb-type fluorescent lamp will be described with reference to FIG. FIG. 8 is an external perspective view of an illuminating device including a bulb-type fluorescent lamp.
The lighting device 30 shown in the drawing is, for example, a pendant-type lighting fixture, and includes a socket (not shown) connected to a cord 31, a cap 32 provided so as to cover the socket, and a base 23 screwed into the socket. It is comprised from the bulb-type fluorescent lamp 22 connected together.

  As described above, since the lighting device 30 (lighting fixture) includes the fluorescent lamp device (bulb-shaped fluorescent lamp) in which the inverter device shown in FIG. 1 is incorporated, noise generated at the start of lighting is eliminated, and thus the lighting device is turned on. It is possible to provide a lighting apparatus that does not affect the present apparatus and other equipment due to noise at the start.

  In addition, although the pendant type lighting fixture was shown as an example as a lighting fixture which has the bulb-shaped fluorescent lamp 22, the downlight installed in a corridor, a toilet, etc., the lighting fixture with a ceiling fan, and the some bulb-shaped fluorescent lamp 22 are used. It may be a chandelier.

It is a circuit diagram of the inverter apparatus which shows embodiment of this invention. It is a graph which plots and shows the oscillation frequency at the time of lighting with the capacitance value of the capacitor | condenser 16 as a parameter. It is a waveform diagram of the voltage and current of the N-channel FET when the fluorescent lamp is lit. It is a waveform diagram of the voltage and current of the P-channel FET when the fluorescent lamp is lit. It is a graph which plots and shows the oscillation frequency at the time of start-up with the capacitance value of capacitor 16 as a parameter. It is a waveform diagram of the current, voltage and power of the P-channel FET at the start of lighting of the fluorescent lamp. It is sectional drawing which shows the fluorescent lamp apparatus provided with the inverter apparatus of embodiment of this invention. It is an external appearance perspective view of the illuminating device provided with the bulb-type fluorescent lamp. It is a waveform diagram of the current, voltage and power of a P-channel FET at the start of lighting a fluorescent lamp in the prior art.

Explanation of symbols

1 AC power supply, 2 capacitor, 3 inductor, 4 full wave rectifier circuit, 5 smoothing capacitor, 6 N channel FET, 7 P channel FET, 8 ballast coil, 8a primary winding, 8b secondary winding, 9 DC cut capacitor, 10 fluorescent lamp, 11 starting capacitor, 12, 13, 14 resistance for starting, 15 inductor, 16 capacitor,
17 Capacitor of delay circuit, 18, 19 Zener diode, 20 Snubber capacitor, 21 Resistance of delay circuit, 22 Light bulb type fluorescent lamp, 23 Base, 24 Cover,
25 Globe, 26 Fluorescent lamp, 27 Substrate, 28 Partition plate, 30 Lighting fixture,
31 code, 32 shades.

Claims (6)

A full-wave rectifier circuit;
A smoothing capacitor for smoothing the output of the full-wave rectifier circuit;
N-channel and P-channel switching elements provided between the output terminals of the smoothing capacitor and connected in series;
A ballast coil connected to a connection point of the N-channel switching element and the P-channel switching element;
A secondary winding magnetically connected to the ballast coil;
A resonance circuit provided between both ends of the secondary winding,
An inverter device, wherein a resonance voltage generated in the resonance circuit is applied to each of the switching elements of the N channel and the P channel via a series circuit of a resistor and a capacitor to perform an on / off operation alternately.   2. The inverter device according to claim 1, wherein the N-channel switching element is provided on a high potential side.   3. The inverter device according to claim 1, wherein the source sides and the gate sides of the N-channel and P-channel switching elements are connected to each other.   A first resistor connected in parallel between the drain and source of the N-channel switching element, and a second resistor inserted between the secondary winding and the gate of each of the N-channel and P-channel switching elements. And a starting circuit for applying a voltage to each of the N-channel and P-channel switching elements, and a third resistor connected in parallel between the gate and drain of the P-channel switching element The inverter device according to any one of claims 1 to 3, wherein the inverter device is provided. An inverter device according to any one of claims 1 to 4,
A fluorescent lamp device comprising a fluorescent lamp that is turned on by the inverter device.   An illumination device comprising the fluorescent lamp device according to claim 5.

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