JP2003187991A - Inverter device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to control a load output without increasing the input current distortion in an inverter device lighting an incandescent lamp at a high frequency. <P>SOLUTION: A series circuit of capacitors C2, C3, and a series circuit of switching elements SW1, SW2 are connected in parallel to an output end of a rectification part 1 converting AC power source to DC power source. In the inverter device in which an incandescent lamp load 3 is connected to a secondary side of a transformer T connected between a connecting point of the capacitors C2, C3 and a connecting point of the switching elements SW1, SW2, output to the incandescent lamp load 3 is controlled by making an On-duty of the switching elements SW1, SW2 variable in a range of not more than 50%. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device which rectifies a commercial power source and converts it into a high frequency to light an incandescent lamp load.

[0002]

2. Description of the Related Art A conventional incandescent lamp inverter device is shown in FIG.
As shown in FIG. 1, the phase control unit 5, the rectification unit 1, and the inverter unit 2
And is connected to a commercial AC power source. The phase control unit 5 used in this inverter device is originally used by connecting an AC power supply, a phase control unit and an incandescent light bulb in series, and controls the output to the incandescent light bulb. Inverter devices for incandescent lamps also usually use a phase control unit for this type of incandescent lamp.

The phase controller 5 comprises a triac TR, a diac DI, a variable resistor R1 and a capacitor C1. When the input power supply V1 is applied, the capacitor C1 is charged with electric charge via the variable resistor R1. When the voltage of the capacitor C1 reaches the threshold voltage of the DIAC DI, the DIAC DI turns on and the triac TR turns on.
To do. As a result, the voltage V2 is applied to the rectifier 1 with a certain phase delay (see FIG. 18).

The rectifying section 1 is composed of a capacitor C2, a coil L and a diode bridge DB. The capacitor C2 and the coil L form a filter. The diode bridge DB rectifies the voltage V2 and converts it into a voltage V3.
As shown in FIG. 18, the voltage V2 is a phase-controlled AC voltage waveform, and the voltage V3 is a phase-controlled pulsating voltage waveform.

The inverter section 2 has a resistor R2 and a capacitor C.
3, C4, C5, C6, diodes D1, D2, D3,
It is a two-stone half bridge inverter composed of a trigger element SBS, transistors Q1 and Q2, an output transformer T, a current transformer CT, and an incandescent lamp 3. When the voltage V3 is applied to the inverter unit 2, the capacitor C6 is charged with electric charge via the capacitor C5 and the resistor R2. When the voltage of the capacitor C6 reaches the threshold voltage of the trigger element SBS, the trigger element SBS is turned on, a current flows through the base of the transistor Q2, and the transistor Q2 is turned on. As a result, the capacitor C4 → output transformer T
→ Current transformer CT → Transistor Q2 → Current flows through the path of capacitor C4. Eventually transistor Q2
The current flowing in the transistor Q2 decreases, and the current transformer CT for current feedback applies a reverse bias to the base of the transistor Q2, so that the transistor Q2 is turned off. At the same time, forward bias is applied to the base of the transistor Q1, so that current flows into the base of the transistor Q1 and the transistor Q1 is turned on. As a result, the capacitor C3 → transistor Q1 → current transformer CT → output transformer T →
A current flows through the path of the capacitor C3. Eventually, the current flowing through the transistor Q1 decreases, the current transformer CT for current feedback applies a reverse bias to the base of the transistor Q1, and the transistor Q1 turns off and the transistor Q2 turns on. Oscillation continues by repeating this operation. Further, since the power source (V3) of the inverter unit 2 is a pulsating current, the trigger element SBS is turned on every half cycle.
Then, the oscillation has started. Energy is supplied to the load via the output transformer T.

In this circuit, the voltage across the capacitors C3 and C4 is approximately V3 / 2 in operation. As a result, the voltage of V3 / 2 is also applied to the primary side (inverter side) of the output transformer T. Since the input voltage V3 of the inverter unit 2 is obtained by rectifying the phase-controlled voltage V2, the voltage V4 applied to the primary side of the output transformer T is proportional to the voltage V2. The voltage V5 applied to the load (secondary side of the output transformer T) is proportional to the voltage V4 on the primary side.
5 is proportional to the voltage V2. That is, as shown in FIG. 18, the phase of the voltage V1 is controlled by the phase controller 5 to control the voltage V2.
By so setting, the voltage V5 is controlled. The output to the load can be controlled (dimming) by controlling the voltage V5. At this time, the current I1 flowing into the inverter unit 2 has a waveform similar to the voltage V2. The above is the conventional incandescent lamp inverter device.

[0007]

In the conventional inverter device, since the phase control is used when dimming, the input current distortion becomes large, which may adversely affect other electric devices sharing the power supply line. There is a problem that there is. The present invention has been made in view of the above circumstances, and an object thereof is to make it possible to control a load output in an inverter device that lights an incandescent lamp at high frequency without increasing input current distortion.

[0008]

According to the present invention, in order to solve the above problems, as shown in FIG. 1, a rectifying section 1 for converting an AC power source into a DC power source, and an output of the rectifying section 1. A series circuit of two capacitors C2 and C3 connected in parallel to the end, a series circuit of two switching elements SW1 and SW2 connected in parallel to the output end of the rectifying unit 1, and a connection of the two capacitors C2 and C3. In an inverter device including a transformer T having a primary side connected between a point and a connection point of the two switching elements SW1 and SW2, and an incandescent lamp load 3 connected to a secondary side of the transformer T. The output to the incandescent lamp load 3 is controlled by making the ON duty of each of the switching elements SW1 and SW2 variable within a range of 50% or less.
With this configuration, since the ON duty is merely changed, the input current distortion does not increase unlike the case of the phase control.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a circuit diagram of an inverter device according to a first embodiment of the present invention. This inverter device includes a rectification unit 1 connected to a commercial AC power supply,
It is composed of an inverter unit 2 connected to the output of the rectifying unit 1. The rectification unit 1 includes a capacitor C1, a coil L, and a diode bridge DB. The capacitor C1 and the coil L form a filter. The diode bridge DB rectifies the input voltage V1 and outputs the voltage V2.

The inverter unit 2 includes capacitors C2 and C
3, output transformer T, switching elements SW1, SW
It is a two-stone half bridge inverter composed of 2, diodes D1 and D2, incandescent lamp 3, and inverter control IC 4. The inverter control IC 4 is a switching element SW
The output to the incandescent lamp load 3 is controlled by making ON duty of 1 and SW2 variable within a range of 50% or less.

FIG. 2 shows an operation waveform diagram of this circuit. As shown in FIG. 2, the switching elements SW1 and SW2 are alternately turned on and off so that the incandescent lamp 3 (secondary side of the output transformer T).
A voltage V3 is applied to. Switching element SW1, S
The periods in which W2 is turned on are tsw1 and tsw2, respectively, and the switching elements SW1 and SW2 are turned on once-OF.
Ton1, ton2 are the periods that are ON during the period of F
Then, in this embodiment, ton = ton1 = ton
2, tsw = tsw1 = tsw2, tsw <50 μse
c. The voltage is applied to the incandescent lamp 3 while one of the switching elements SW1 and SW2 is on, but the incandescent lamp 3 is applied while both are off at the same time.
No voltage is applied to the device.

Here, tsw = Tsw is constant, and ton
Is changed in the range of 0 to Tsw / 2, it is possible to change the ON duty of the switching elements SW1 and SW2 and control the output to the load (dimming the load). As shown in FIG. 3, V3 (average value) is proportional to ton.

When the above control is performed, the output to the load is 10
When it is made smaller than 0%, the inverter unit 2 is accompanied by a rest period, and thus the current I2 input to the inverter unit 2 becomes a rectangular wave as shown in FIG. However, since the harmonic component is removed by the filter configured by the capacitor C1 and the coil L of the rectification unit 1, the current I1 input to the rectification unit 1 is removed.
Has a waveform close to a sine wave. With the above configuration, it is possible to provide an inverter device in which the input current distortion does not increase even when the load output is changed.

Even if the AC power source V1 changes from a predetermined voltage by utilizing the above control, the output V3 (average value) to the load is changed by changing the ON duty of each of the switching elements SW1 and SW2. It can be made substantially the same as when V1 is a predetermined voltage.

0 <X <50, 0 <Y <100, Y ≦ 2X
The following explanation will be given. As shown in FIG. 5, the ON duty of the switching elements SW1 and SW2 is set to (50−
When V1 is set to the rated voltage V1T in the state of (X)%, V
3 is set to the rated voltage V3T (point). ON
When the duty is constant at (50−X)%, V1 = (100−
Y) × V1T / 100, V3 = (100−
Y) × V3T / 100 (point). ON here
By setting the duty to (50−X) × 100 / (100−Y), V3 = V3T can be set (point). Conversely, when the ON duty is (50-X)% constant, V
When 1 = (100 + Y) × V1T / 100, V
3 = (100 + Y) × V3T / 100 (point). Here, the ON duty is (50−X) × 100
By setting / (100 + Y), V3 = V3T can be obtained (point). By controlling as described above, the output to the load can be kept constant.

The switching elements SW1 and SW2 of the inverter section 2 shown in FIG. 1 may be electrical switching elements such as bipolar transistors and MOS-FETs. The incandescent lamp load 3 may use a halogen bulb.

Further, the inverter section shown in FIG. 1 has switching elements SW1, SW2, SW3, SW shown in FIG.
4, diodes D1, D2, D3, D4, transformer T,
A four-stone inverter unit including the incandescent lamp 3 and the inverter control IC 4 may be used. However, in the circuit of FIG. 6, the switching elements SW1 and SW4 are turned on at the same time.
-OFF, the switching elements SW2 and SW3 are also turned ON-OFF at the same time, and turned ON-OFF alternately, respectively, which is a so-called full-bridge inverter.

Further, in the inverter device shown in FIG. 1, when the power consumption of the load increases at the end of the life of the load, the load voltage V3 is reduced in order to reduce the power consumption of the load.
The ON duty of the switching elements SW1 and SW2 is reduced so that By doing so, the life of the load can be extended as compared with the case where the load voltage V3 is not changed.

(Embodiment 2) In the inverter device of Embodiment 1 shown in FIG. 1, ton = Ton is constant and tsw is changed within a range of 2 × Ton to 50 μs to change the ON duty of the switching elements SW1 and SW2. The output to the load can be controlled (dimming the load) with. As a result, as shown in FIG. 7, V3 (average value) is ts
The value is inversely proportional to w. With the above configuration, it is possible to provide an inverter device in which the input current distortion does not increase even when the load output is changed.

(Third Embodiment) FIG. 8 shows a third embodiment of the present invention.
2 is a circuit diagram of the inverter device of FIG. This inverter device includes a rectification unit 1 connected to a commercial AC power supply and a rectification unit 1
It is composed of an inverter unit connected to the output of. The rectification unit 1 includes a capacitor C1, a coil L, and a diode bridge DB. The capacitor C1 and the coil L form a filter. The diode bridge DB rectifies the AC power supply.

The inverter unit is the inverter control power supply unit 2
1, an inverter control unit 22, and an inverter drive unit 23. First, the inverter control power supply unit 21 includes a resistor R
3, R4, capacitor C4, Zener diode ZD,
Transistor Q3, 5V output three-terminal regulator RE
G (for example, AN7805 manufactured by Matsushita Electric Industrial Co., Ltd.). Due to the power supply supplied from the rectification unit 1, a current flows through the path of the resistor R3 → the resistor R4 → the Zener diode ZD. Here, the Zener diode ZD has a Zener voltage of 25V, and the base voltage of the transistor Q3 is 25V. Since the voltage at the emitter of the transistor is 0.7V lower than the voltage at the base, the input voltage of the three-terminal regulator REG becomes 24.3V and the output voltage becomes 5V.

Next, the inverter control section 22 includes a variable resistor R5, capacitors C5, C6, C7, C8, diodes D3, D4, a microcomputer 24, and high voltage drivers DR1, D.
It is composed of R2 (for example, IR2117 manufactured by IR Co.).
After the output voltage of the inverter control power supply unit 21 reaches 5V, the microcomputer 24 and the high breakdown voltage drivers DR1 and DR2 can operate. The microcomputer 24 has a reset function and does not operate unless the voltage at the Vcc terminal of the microcomputer 24 reaches 5V. As shown in FIG. 9, the voltage V1 at the terminal P1 and the voltage V2 at the terminal P0 of the microcomputer 24 are alternately set to the high level and the low level. In the high withstand voltage driver DR2, the voltage V4 of the HO terminal becomes High level while the voltage V1 of the terminal IN is at High level, and the high withstand voltage driver DR1
Is the terminal H during the period when the voltage V2 of the terminal IN is at the high level.
The voltage V3 of O becomes High level.

Next, the inverter drive unit 23 includes a resistor R
1, R2, capacitors C2, C3, diodes D1, D
2, a transformer T, switching elements Q1 and Q2, and an incandescent lamp 3. The switching elements Q1 and Q2 are MOSs that turn on when the gate-source voltage is about 4V.
-FET. The switching element Q2 is turned on while V4 is at the high level, and the switching element Q1 is turned on while V3 is at the high level, and the voltage VLA is output to the incandescent lamp as shown in FIG. From the above, V4 and V3
The voltage is applied to the incandescent lamp 3 while one of them is at the high level, and the voltage is not applied to the incandescent lamp 3 at the same time when both of them are at the low level.

The microcomputer 24 of the inverter control section 22 changes the value of the resistor R5 to change the values of V1 and V2 to High.
V1, for the repetition period of the h level and the Low level
The ratio of the period when V2 is at the high level can be changed. Therefore, V and V3 are respectively V level during the High level and Low level repetition periods.
4, the ratio of the period when V3 is at the high level can be changed, and the output to the load can be controlled (the load can be dimmed).

As described above, in this embodiment, by using the microcomputer 24 in the inverter control unit 22, it is possible to provide an inverter device in which the input current distortion does not increase even when the output of the load is changed.

(Embodiment 4) FIG. 10 is a circuit diagram of an inverter controller used in Embodiment 4 of the present invention. The configuration of the main circuit is the same as that of the third embodiment shown in FIG. 8, and the circuit of FIG. 10 is connected instead of the inverter control unit 22 of FIG. 8. Each terminal a to e of FIG. Are respectively connected to terminals a to e of the main circuit. The inverter control unit of FIG. 10 includes resistors R5 and R6 (where R6 is a variable resistor), capacitors C5, C6, C7, C8, C9 and C.
10, timer TM (eg NEC μPC155
5), binary counter BC (for example, μPD manufactured by NEC)
4024B), multiplexer MP (for example, μPD40518 manufactured by NEC), high voltage driver DR1, DR2
(For example, IR2117 manufactured by IR Co.). After the output voltage of the inverter control power supply unit reaches 5V, the timer TM, the binary counter BC, the multiplexer MP, and the high breakdown voltage drivers DR1 and DR2 become operable.

As shown in FIG. 11, the voltage V1 of the terminal 3 which is the oscillation output terminal of the timer TM is alternately set to the high level and the low level. Binary counter BC is terminal C
When the voltage V1 of LOCK changes from the High level to the Low level, the voltage V2 of the terminal Q1 alternately becomes the High level and the Low level. In that case, the voltage V1 is Low
When it reaches the level, the voltage V2
Output is retained. In the multiplexer MP, the voltage V2 at the A terminal is simultaneously at the high level while the voltage V2 at the X terminal is
1 is in the high level period, the voltage V3 of the X1 terminal
Becomes High level. Also, the voltage V2 at the A terminal is L
During the period of ow level, the voltage V1 of the X terminal is High at the same time.
During the level period, the voltage V4 of the X0 terminal becomes the High level. The voltage V of the IN terminal of the high voltage driver DR2
3 is in the high level period, the voltage V6 of the HO terminal
Becomes High level. IN of high voltage driver DR1
During the period when the terminal voltage V4 is at the high level, the HO terminal voltage V5 is at the high level. The inverter part
During the period when V6 is High level, the switching element Q
2, the switching element Q1 is turned on and the voltage VLA is applied to the incandescent lamp while V5 is at the high level. From the above, the operation is such that the voltage is applied to the incandescent lamp while either V6 or V5 is at the high level, and the voltage is not applied to the incandescent lamp at the same time when both are at the low level.

In this inverter control unit, by changing the value of the resistor R6, it is possible to change the ratio of the period in which V1 is the High level with respect to the repeating period of the High level and the Low level of V1. Therefore, V
It is possible to change the ratios of the periods in which V6 and V5 are at the high level with respect to the repetition period of the high level and the low level of V6 and V5, respectively, and control the output to the load (dimming the load). As an example, FIG. 12 shows a case where the resistance value of the resistor R6 is doubled as compared with the case of FIG.

As described above, in this embodiment, by using a general-purpose timer, a multiplexer, and a binary counter in the inverter control unit, it is possible to provide an inverter device in which the input current distortion does not increase even when the output of the load is changed. I can.

(Fifth Embodiment) FIG. 13 is a circuit diagram of an inverter control unit used in a fifth embodiment of the present invention. The configuration of the main circuit is the same as that of the third embodiment shown in FIG. 8, and the circuit of FIG. 10 is connected instead of the inverter control unit 22 of FIG. 8. Each terminal a to e of FIG. Are respectively connected to terminals a to e of the main circuit. The inverter control unit of FIG. 13 includes resistors R5, R6, R7 and R8 (however, resistors R7 and R8 form a double volume resistor), capacitors C5, C6, C7, C8, C9 and C1.
0, C11, C12, C13, C14, diode D
3, D4, timers TM1, TM2, TM3 (for example, NE
C company μPC1555), multiplexer MP (for example, NEC company μPD4051B), high voltage driver DR
1, DR2 (for example, IR2117 manufactured by IR Co.). After the output voltage of the inverter control power supply unit reaches 5V, timers TM1, TM2, TM3 and multiplexer M
The P and high breakdown voltage drivers DR1 and DR2 can operate.

As shown in FIG. 14, the voltage V1 of the terminal 3 which is the oscillation output terminal of the timer TM1 alternately becomes the high level and the low level. Here, resistors R5 and R6 having the same resistance value are used, and (V1 High level period) = (V1 Low level period). In the multiplexer MP, the voltage V2 at the X1 terminal is at the high level while the voltage V1 at the A terminal is at the high level. Further, the voltage V3 of the XO terminal becomes High level while the voltage V1 of the A terminal is Low level. When the voltage V2 of the terminal 2 becomes Low level, the timer TM3 sets the voltage V6 of the terminal 3 which is an oscillation output terminal to High level. V
6 is controlled by the resistor R8, and is ((High level period of V6) <(1/2 of repetition period of High level and Low level of V1)). In the high withstand voltage driver DR2, the voltage V7 of the terminal HO is at the high level while the voltage V6 of the terminal IN is at the high level. Timer TM2
When the voltage V3 of the terminal 2 becomes low level, the voltage V4 of the terminal 3 which is an oscillation output terminal becomes high level.
V4 is controlled by the resistor R7, and (V4 High level period) <(1/2 of repetition period of High level and Low level of V1). High voltage driver DR1
When the voltage V4 of the terminal IN becomes High level, the terminal H
The voltage V5 of O becomes High level.

In the inverter section, the switching element Q2 is turned on and V5 is Hi during the period when V7 is at the high level.
During the gh level period, the switching element Q1 is turned on, and the voltage VLA is applied to the incandescent lamp as shown in FIG. From the above, voltage is applied to the incandescent lamp while either V7 or V5 is at the high level, and both are simultaneously Lo
During the period of w level, the operation is such that no voltage is applied to the incandescent lamp.

In this inverter control section, V is changed by changing the values of the double volume resistors (R7, R8).
It is possible to change the period in which V4 and V6 are in the high level with respect to the repetition period of the high level and the low level in 4, 4 respectively. Therefore, V7, V
It is possible to control the output to the load (dimming the load) by changing the ratio of the periods in which V7 and V5 are at the High level for the repetition period of the High level and the Low level of 5, respectively. You can

As described above, in this embodiment, by using the general-purpose timer and the multiplexer in the inverter control unit, it is possible to provide the inverter device in which the input current distortion does not become large even if the output of the load is changed.

(Embodiment 6) FIG. 15 is a circuit diagram of an inverter controller used in Embodiment 6 of the present invention. The configuration of the main circuit is the same as that of the third embodiment shown in FIG. 8, and the circuit of FIG. 10 is connected instead of the inverter control unit 22 of FIG. 8. Each terminal a to e of FIG. Are respectively connected to terminals a to e of the main circuit. The inverter control unit of FIG. 15 includes resistors R5, R6, R7, R8, R9,
R10 (however, resistors R7 and R8 form a double volume resistor), capacitors C5, C6, C7, C
8, C9, C10, C11, C12, C13, C14,
Diodes D3, D4, bipolar transistor Q3,
Q4, timers TM1, TM2 and TM3 (eg NEC μPC1555), multiplexer MP (eg NE
C company μPD4051B), high voltage driver DR1, D
It is composed of R2 (for example, IR2117 manufactured by IR Co.).
After the output voltage of the inverter control power supply unit reaches 5V, the timers TM1, TM2 and TM3, the multiplexer MP, and the high breakdown voltage drivers DR1 and DR2 become operable.

As shown in FIG. 16, the voltage V1 at the terminal 3 which is the oscillation output terminal of the timer TM1 alternately becomes the high level and the low level. Here, resistors R5 and R6 having the same resistance value are used, and (V1 High level period) = (V1 Low level period). In the multiplexer MP, the voltage V2 of the X1 terminal becomes High level while the voltage V1 of the A terminal is High level, and the voltage V3 of the X0 terminal becomes High level when the voltage V1 of the A terminal is Low level. In the timer TM3, when the voltage V2 of the terminal 2 becomes low level, the voltage V7 of the terminal 3 which is an oscillation output terminal becomes high level. V7 is resistance R
Controlled by 9 (V7 is high level period)
≦ (1/2 of repetition cycle of High level and Low level of V1). High-voltage driver DR2 terminal IN
Voltage V8 is V3 is High level and V7 is High level
When it becomes the level, the transistor Q4 turns on, so it goes Low
When V3 is High level and V7 is Low level, the transistor Q4 is turned off, so Hi
It becomes gh level. The voltage V9 of the terminal HO of the high breakdown voltage driver DR2 becomes High level while V8 is at High level. When the voltage V2 of the terminal 2 becomes low level, the timer TM2 changes the voltage V4 of the terminal 3 which is an oscillation output terminal to H level.
It becomes the high level. V4 is controlled by the resistor R7, and ((V4 is a high level period)) ≤ (High of V1
It is 1/2 of the repetition cycle of the h level and the Low level. The voltage V6 of the terminal IN of the high breakdown voltage driver DR1 is V
When 2 is High level and V4 is High level,
Since the transistor Q3 is turned on, it becomes Low level,
When V2 is at the high level and V4 is at the low level, the transistor Q3 does not turn on and is at the high level. The voltage V5 of the terminal HO of the high voltage driver DR1 is V6
Becomes High level during the period of High level. In the inverter section, the switching element Q2 is turned on while V9 is at the high level, and the switching element Q1 is turned on while V5 is at the high level, and the voltage VLA is applied to the incandescent lamp as shown in FIG. From the above, V9, V
5 The voltage is applied to the incandescent lamp during the period when one of them is at the high level, and the voltage is not applied to the incandescent lamp during the period when both are at the low level (rest period).

In this inverter control section, the value of V4 is changed by changing the value of the double volume resistors (R7, R9).
The period during which V4 and V7 are at the high level can be changed with respect to the repetition period of the high level and the low level of V7. Therefore, V9,
With respect to the repetition period of High level and Low level of V5, it is possible to change the period in which V9 and V5 are High level, respectively, and it is possible to control the output to the load (dimming the load). . In the present embodiment, (the period when V7 and V4 are in the high level) can be set to = (1/2 of the repetition period of the high level and the low level of V7 and V4, respectively), and the output to the load is zero. It can be controlled. With the above configuration, it is possible to provide an inverter device in which the input current distortion does not increase even when the load output is changed and the load output can be dimmed to zero.

[0038]

According to the present invention, a rectification section for converting an AC power supply into a DC power supply, a series circuit of two switching elements connected between output terminals of the rectification section, and connection of the two switching elements. In an inverter device including a transformer whose primary side is connected to a point and an incandescent lamp load connected to the secondary side of the transformer, the ON duty of each switching element is variable within a range of 50% or less. Since the output to the incandescent lamp load is controlled by doing so, the power supply is shared by making the input current close to a sine wave and reducing the harmonic components contained in the input current. It is now possible to provide an inverter device that is unlikely to adversely affect the electronic device of.

[Brief description of drawings]

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

FIG. 2 is a first operation explanatory diagram of the first embodiment of the present invention.

FIG. 3 is a second operation explanatory diagram of the first embodiment of the present invention.

FIG. 4 is a third operation explanatory diagram of the first embodiment of the present invention.

FIG. 5 is a fourth operation explanatory diagram of the first embodiment of the present invention.

FIG. 6 is a circuit diagram of a modified example of the first embodiment of the present invention.

FIG. 7 is an operation explanatory diagram of the second embodiment of the present invention.

FIG. 8 is a circuit diagram of a third embodiment according to the present invention.

FIG. 9 is an operation explanatory diagram of the third embodiment of the present invention.

FIG. 10 is a circuit diagram of an inverter control unit used in a fourth embodiment of the present invention.

FIG. 11 is a first operation explanatory diagram of the fourth embodiment according to the present invention.

FIG. 12 is a second operation explanatory diagram of the fourth embodiment according to the present invention.

FIG. 13 is a circuit diagram of an inverter control unit used in a fifth embodiment of the present invention.

FIG. 14 is an operation explanatory diagram of the fifth embodiment of the present invention.

FIG. 15 is a circuit diagram of an inverter control unit used in a sixth embodiment of the present invention.

FIG. 16 is an operation explanatory diagram of the sixth embodiment of the present invention.

FIG. 17 is a circuit diagram of a conventional incandescent lamp inverter device.

FIG. 18 is an operation explanatory diagram of a conventional incandescent lamp inverter device.

[Explanation of symbols]

1 Rectifier 2 Inverter section 3 incandescent lamps 4 Inverter control IC

Claims (4)

[Claims] 1. A rectification unit for converting an AC power supply into a DC power supply, a series circuit of two switching elements connected between output terminals of the rectification unit, and a primary side at a connection point of the two switching elements. In an inverter device including a connected transformer and an incandescent lamp load connected to the secondary side of the transformer, by changing the ON duty of each of the switching elements within a range of 50% or less, an incandescent lamp load is set. An inverter device characterized by controlling an output to. 2. The inverter control unit according to claim 1, wherein the ON-OFF repetition cycle of each switching element is made constant and the ON period of each switching element is changed to a load by changing the ON period. An inverter device characterized by controlling the output of the inverter. 3. The inverter control unit according to claim 1, wherein the ON-OFF repetition cycle is changed while the ON period of each switching element is once ON-OFF is made constant to control the output to the load. An inverter device characterized in that 4. The method according to claim 1, wherein when the AC power supply fluctuates from a predetermined voltage, the output to the load is substantially the same as when the AC power supply has a predetermined voltage. An inverter device characterized by changing the ON duty of a switching element.