JP3252540B2 - Inverter device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device for converting a commercial AC power supply into a DC voltage, switching the DC voltage by turning on / off a switching means, and supplying high-frequency power to a load.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a circuit diagram of a conventional inverter device disclosed in Japanese Unexamined Patent Application Publication No. H11-209, in which a DC voltage obtained by rectifying a commercial power supply 1 by a rectifier circuit 2 is smoothed by a smoothing capacitor 3 and then connected in series. The high-frequency power is applied to the transistors 4 and 5, which are the switching means, and the control circuit 8 controls the transistors 4 and 5 to alternately turn on and off at a high speed. Second for
To the load (for example, a discharge lamp) via the coil 9 or the coupling capacitor 12. The diodes 6 and 7 are connected in antiparallel to the transistors 4 and 5, respectively, for the purpose of flowing a regenerative current. Reference numeral 10 denotes a discharge lamp, and 11 denotes a capacitor connected in parallel to the discharge lamp. A resonance circuit is formed by the second coil 9 for current limitation and the capacitor 11, and a high voltage required for discharging is generated from both ends of the capacitor 11. The load circuit 13 of this inverter device includes a second coil 9 for limiting current, a discharge lamp 10, a capacitor 11, and a coupling capacitor 12.

The conventional inverter device is configured as described above. First, when the transistor 5 is on and the transistor 4 is off, a current flows from the smoothing capacitor 3 to the load circuit 13 via the transistor 5 in one direction. This current flows and charges the coupling capacitor 12 in the load circuit 13. When the transistor 5 is off and the transistor 4 is on, the charge of the coupling capacitor 12 is discharged via the transistor 4,
A current flows through the load circuit 13 in a direction opposite to the above. Therefore, high-frequency power is supplied to a load (for example, a discharge lamp). FIG. 21 is an operation waveform diagram of the circuit.
In the figure, (a) shows the input voltage from the commercial power supply 1, and (b) shows the input current from the commercial power supply 1. As shown in the figure, in the circuit, the input current flows only when the power supply voltage of the commercial power supply 1 is near the peak value, the input current waveform becomes a pulse-like waveform, and the peak value is high.

[0004]

Since the conventional inverter device has the above-structured capacitor input type, the input current waveform has a sharp pulse-like shape, which causes a reduction in power factor and harmonic interference. It has become.

The present invention has been made to solve such a problem, and an object of the present invention is to provide an inverter device which can reduce input distortion, has a high power factor, and has few harmonics.

[0006]

An inverter device according to a first aspect of the present invention is provided between a rectifier circuit for rectifying an AC voltage and outputting a DC voltage and an output terminal of the rectifier circuit, and is connected in series with each other. First and second switching means that alternately turn on and off, diodes that are equivalently connected in antiparallel to each of the first and second switching means, and turn on and off the first and second switching means A control circuit for controlling; a smoothing capacitor provided between a rectifier circuit and a series circuit of the first and second switching means;
In an inverter device including a load circuit connected between a connection point of the first and second switching means and a smoothing capacitor, a first boosting coil inserted between the rectifier circuit and the smoothing capacitor is provided. A separation diode connected in series with the first coil for boosting to separate the voltage of the rectifier circuit and the voltage of the smoothing capacitor, and a connection point of a series circuit formed by the first coil for boosting and the separation diode. Between the rectifier circuit and the load circuit via the first coil for boosting, which is connected between the rectifier circuit and the load circuit, and is turned on / off in synchronization with either the first or second switching means. And a diode connected in series with the third switching means and blocking a reverse voltage applied to the switching means.

An inverter device according to a second aspect of the present invention is provided with a transformer which is inserted in series with a load circuit, detects a current flowing from the smoothing capacitor to the load circuit, and drives a third switching means. It is.

According to a third aspect of the present invention, in the inverter device, the load circuit includes a discharge lamp, and the current limiting second coil includes a transformer that also serves to detect the load current.

In the inverter device according to a fourth aspect of the present invention, the load circuit includes a discharge lamp, a second coil for limiting current, and a coupling capacitor.
And a preheating transformer that is connected between the connection point of the switching means and the smoothing capacitor, supplies power to the filament of the discharge lamp, and drives the third switching means.

The inverter device according to claim 5 of the present invention turns on in synchronization with the first or second switching means, changes the on-pulse width according to the value of the load current, and sets the third pulse during the on operation. And a time-limit circuit for driving the switching means.

The inverter device according to claim 6 of the present invention is provided with a plurality of switches for setting an on-pulse width of the timed circuit.

An inverter device according to a seventh aspect of the present invention is provided with a load current detecting means for detecting a current flowing in a load circuit and setting an on-pulse width of the timed circuit by a detection output.

An inverter device according to claim 8 of the present invention is provided between a rectifier circuit for rectifying an AC voltage and outputting a DC voltage, and an output terminal of the rectifier circuit, and is connected in series with each other and alternately turns on and off. A first and second switching means, a diode equivalently and anti-parallel connected to each of the first and second switching means, a control circuit for controlling on / off of the first and second switching means, An inverter device including a rectifier circuit and a smoothing capacitor provided between the first and second switching means, and a load circuit connected between the connection point of the first and second switching means and the smoothing capacitor. A first coil for boosting inserted between the rectifier circuit and the smoothing capacitor, and a voltage between the rectifier circuit and the smoothing capacitor connected in series with the first coil for boosting. The load is connected between a separation diode that separates a voltage, a connection point of a series circuit formed by a first coil for boosting and a separating diode, and a load circuit, and is connected to a first coil for boosting from a rectifier circuit. And a diode for supplying a current flowing through the load circuit.

In the inverter device according to a ninth aspect of the present invention, the load circuit includes a discharge lamp, a second coil for limiting current, and a coupling capacitor, and the first circuit for boosting.
And an additional winding for supplying the filament power of the discharge lamp.

[0015]

In the inverter device according to the first aspect of the present invention, the pulsating current output from the rectifier circuit is the first voltage for boosting.
And the second switching means and the third switching means are simultaneously turned on by the drive signal of the control circuit, and the current loop flowing to the load circuit based on the charging voltage of the smoothing capacitor. And two current loops that flow directly from the rectifier circuit to the load circuit via the first coil for boosting and the third switching means, and a back electromotive voltage is applied to the first coil for boosting by the latter current. The counter electromotive voltage causes a high frequency current to flow in accordance with the voltage of the commercial power supply. At the same time, the diode connected in series with the third switching means prevents the current from the current limiting second coil from flowing to the third switching means, and a reverse voltage is applied to the third switching means. To prevent

In the inverter device according to a second aspect of the present invention, the current flowing in the load circuit is detected by the transformer inserted in series with the load circuit, and the third switching means is turned on using the secondary voltage of the transformer.・ It is driven off.

In the inverter device according to claim 3 of the present invention, when the load is a discharge lamp, the third winding is formed by the additional winding of the second coil for limiting the current, which is indispensable for the load circuit.
Are turned on and off.

In the inverter device according to a fourth aspect of the present invention, the third switching means is turned on / off by the additional winding of the preheating transformer for preheating the filament of the discharge lamp.

In the inverter device according to a fifth aspect of the present invention, a time signal for a predetermined time is output from the time circuit using the drive signal of the first or second switching means as a synchronization signal, and the third signal is output from the time circuit. The switching means is driven on and off.

In the inverter device according to claim 6 of the present invention, the pulse width of the ON pulse output from the timed circuit is set by switching a switch corresponding to the current flowing through the load circuit.

In the inverter device according to claim 7 of the present invention, the current flowing through the load circuit is detected, and the pulse width of the ON pulse output from the timed circuit is set by the detection output.

In the inverter device according to the present invention, the pulsating current output from the rectifier circuit is charged to the smoothing capacitor via the first coil for boosting and the separating diode, and is driven by the drive signal of the control circuit. The second switching means is turned on, and a current loop flowing to the load circuit based on the charging voltage of the smoothing capacitor and a current loop flowing directly from the rectifier circuit to the load circuit via the first coil and diode for boosting. One is provided.

In the inverter device according to the ninth aspect of the present invention, the filament power of the discharge lamp is supplied by the additional winding provided in the first coil for boosting.

[0024]

[Embodiment 1] FIG. 1 is a circuit diagram showing a first embodiment of the present invention.
3 is similar to the conventional device. In addition to the conventional inverter device, a series circuit of a first coil 14 for boosting and a separating diode 15 is inserted between the rectifier circuit 2 and the smoothing capacitor 3, and the coil 14 and the separating diode 15 are further inserted.
The series circuit of the transistor 16 and the diode 17 as the third switching means is connected to the connection point of the series circuit and the connection point of the current limiting second coil 9 and the discharge lamp 10 in the load circuit 13. Further, a capacitor 18 serving as a filter is inserted into the output terminal of the rectifier circuit 2.

Next, the operation will be described with reference to the operation waveform diagram of FIG. FIG. 2A shows an input voltage waveform from the commercial power supply 1,
(B) is a DC voltage waveform rectified by the rectifier circuit 2.
This rectified voltage charges the smoothing capacitor 3 via the coil 14 and the separation diode 15 as in the conventional case. Therefore, the potential of the smoothing capacitor 3 becomes the DC voltage E [V]. (C)
Is the waveform of the current flowing through the coil 14, (d) is the ON / OFF waveform of the transistor 4 as the first switching means,
(E) is a transistor 5 serving as a second switching means.
(F) is the ON / OFF waveform of the transistor 16 as the third switching means.
(G) is an input current waveform from the commercial power supply 1. In FIG. 2, (d), (e) and (f) are enlarged views of the waveform.

The voltage of the commercial power supply 1 shown in FIG. 2A is rectified by the rectifier circuit 2, and the DC voltage (pulsating current voltage) shown in FIG.
become. The pulsating current output from the rectifier circuit 2 charges the smoothing capacitor 3 via the coil 14 and the separation diode 15. Then, when the transistor 5 is turned on by the drive signal of the control circuit 8, a current flows through the load circuit 13 including the coil 9, the discharge lamp 10 and the coupling capacitor 12 based on the charging voltage of the smoothing capacitor 3, and this current is The ring capacitor 12 is charged. FIG. 2 (d),
Since transistor 4 and transistor 5 alternately turn on and off as shown in FIG.
Is turned off and the transistor 4 is turned on, the electric charge charged in the coupling capacitor 12 is discharged via the discharge lamp 10, the coil 9 and the transistor 4. By repeating this operation, a high-frequency alternating current flows through the discharge lamp 10.

On the other hand, the transistor 16 repeatedly turns on and off in synchronization with the transistor 5 as shown in FIGS. 2 (e) and 2 (f), so that when the transistor 16 is turned on, the output voltage of the rectifier circuit 2 A current flows through the path of 14, the transistor 16, the diode 17, the discharge lamp 10, the coupling capacitor 12, and the transistor 5. This current merges with the current flowing through the coil 9 based on the voltage of the smoothing capacitor 3 to charge the coupling capacitor 12. FIG. 2C shows a waveform of a current flowing from the rectifier circuit 2 to the coil 14, and a high-frequency current flows in accordance with the voltage of the commercial power supply 1. This high-frequency current loses the high-frequency component by the capacitor 18 serving as a high-frequency removing filter, and becomes an envelope current waveform having the waveform shown in FIG. 2C. The input current waveform from the commercial power supply 1 becomes the commercial current as shown in FIG. Power supply 1
Approaching the voltage waveform. Further, the noise component returned to the commercial power supply 1 is removed by the capacitor 18. If a high-frequency current flows through the coil 14, a back electromotive voltage (a boost effect) is generated in the coil 14, and this voltage causes the separation diode 15
, The charging current flows through the smoothing capacitor 3 via the rectifier circuit 2, so that there is no current to charge the smoothing capacitor 3 directly from the rectifier circuit 2. As described above, since the input distortion can be reduced, it is possible to provide an inverter device having a high power factor and generating less harmonics.

The coil 14 also has a function of limiting the current flowing from the rectifier circuit 2 to the load circuit 13. The same effect can be obtained even if the diode 17 inserted between the load circuit 13 and the transistor 16 is not provided.
Has the effect of lowering the withstand voltage of the transistor 16 by preventing the current from the coil 9 from flowing through the transistor 16 and preventing reverse voltage from being applied to the transistor 16. The switching means of the transistors 4, 5, and 16 uses transistors, but the MOS FET
Similar effects can be obtained by using other switching elements such as (field effect transistors).

Embodiment 2 FIG. FIG. 3 is a circuit diagram showing a second embodiment of the present invention.
8 is exactly the same as the first embodiment. Reference numeral 19 denotes a transformer whose primary side is connected to the load circuit 13.
Is connected to the base terminal of the transistor 16 via the resistor 20.

The transistors 4 and 5 are alternately turned on and off in the same manner as in the first embodiment. When the transistor 5 is turned on, the load current passes through the coil 9, the primary side of the transformer 19, the discharge lamp 10 and the transistor 5. Flows,
This current is generated on the primary side of the transformer 19 by an arrow I in FIG.
It flows in the direction shown in 1. Then, a current flows on the secondary side of the transformer 19 in the direction indicated by the arrow I2, and the transistor 16
Turn on. If the transistor 16 is on and the transistor 5 is on, a high-frequency current corresponding to the output voltage of the rectifier circuit 2 flows through the coil 14 as in the first embodiment, and the distortion of the input current can be reduced.

Embodiment 3 FIG. FIG. 4 is a circuit diagram showing a third embodiment of the present invention.
And the transformer 21 is replaced by the load circuit 1
3 is connected. The winding connected between the primary side of the transformer 21, that is, the high potential side of the smoothing capacitor 3 and the discharge lamp 10 plays the same role as the coil 9 of the conventional device or the first embodiment. A current flows through the primary side of the transistor 21, and the transistor 16 is turned on by the secondary current of the transformer 21. If the transistor 16 is on and the transistor 5 is on, a high-frequency current corresponding to the output voltage of the rectifier circuit 2 flows through the coil 14 as in the first embodiment,
The distortion of the input current can be reduced.

Embodiment 4 FIG. FIG. 5 is a circuit diagram showing a fourth embodiment of the present invention. Reference numeral 22 denotes a preheating transformer. The primary side of the preheating transformer 22 is inserted between the connection point of the transistors 4 and 5 and the smoothing capacitor 3.
On the secondary side, three coils are provided, coils A and B are respectively connected to the filament of the discharge lamp 10, and coil C is connected to the transistor 16.

The transistors 4 and 5 are alternately turned on and off alternately in the same manner as in the first embodiment to supply high-frequency power to the load circuit 13 and at the same time to discharge the discharge lamp 10 through the preheating transformer 22.
Preheat power to the filaments. At this time, the transistor 16 is driven by the secondary coil C of the preheating transformer 22, and the high-frequency current flows directly from the commercial power supply 1 to the load circuit 13 as in the first embodiment, and a back electromotive force is generated in the coil 14, With this voltage, a charging current flows to the smoothing capacitor 3 via the separation diode 15. Therefore, there is no current for charging the smoothing capacitor 3 directly from the rectifier circuit 2. The polarity of the secondary coil of the preheating transformer 22 is connected such that a voltage generated when the transistor 5 is turned on turns on the transistor 16. As described above, when the load is a discharge lamp, the distortion of the input current can be reduced by driving the newly provided transistor 16 using the preheating transformer 22 for preheating the discharge lamp.

Embodiment 5 FIG. FIG. 6 is a circuit diagram showing a fifth embodiment of the present invention.
Is basically the same as in the first embodiment, except that the transistor 16
Drive method is different. That is, a timing circuit 23 that outputs a time signal for a predetermined time using a drive signal of the transistor 5 output from the control circuit 8 as a synchronization signal, and a switch 24 that switches the pulse width of the time signal of the time circuit 23 is provided.
The output of the timed circuit 23 drives the transistor 16 on and off.

The operation of the fifth embodiment will be described with reference to the waveform diagram of FIG. FIG. 7A shows ON / OFF of the transistor 4.
(B) ON / OFF waveform of the transistor 5;
(C) is an ON / OFF waveform of the transistor 16.
The timed circuit 23 operates by the drive signal of the transistor 5 which is the output of the control circuit 8, and outputs an on-pulse for a time t1 when the switch 24 is closed, and outputs an on-pulse for a time t2 when the switch 24 is open. I do. The output of the timed circuit 23 drives the transistor 16 on and off.

On the other hand, the load current flowing through the load circuit 13 is determined by the on / off repetition frequency of the transistors 4 and 5, and when this frequency is high, the load current decreases. This is because the impedance of the coil 9 increases.
Also, the ratio of the pulsating current flowing directly from the output of the rectifier circuit 2 to the load circuit 13 via the transistor 16 and the DC current flowing from the smoothing capacitor 3 via the coil 9 directly becomes the ripple component of the load current. It is clear. Therefore, when the on / off repetition frequency of the transistors 4 and 5 is increased to reduce the load current, the ripple current increases. Therefore, when the load current is set to be small, the switch 24 is closed, and when the load current is set to be large, the switch 24 is opened. As a result, when the load current is set to be small, the pulsating current is small because the on-time of the transistor 16 is short, and when the load current is set to be large, the on-time of the transistor 16 is long and the pulsating current is also large.

When the load current is set to be large, the reason for increasing the pulsating current is that the charge stored in the smoothing capacitor 3 uses the back electromotive voltage generated in the coil 14 so that the load from the smoothing capacitor 3 to the load circuit 13 is increased. This is because when a large amount of current flows, the high-frequency current flowing through the coil 14 needs to be increased. Conversely, the load circuit 1
When the current flowing to the coil 3 is small, the high-frequency current flowing through the coil 14 can be small. As described above, the switch 24 for increasing or decreasing the pulsating current flowing through the load circuit depending on the magnitude of the load current is provided, the power factor is high, the generation of harmonics is small, and the ripple component of the load current can be minimized.

In the fifth embodiment, one switch 24 is provided so as to correspond to two types of load currents. However, when the load current is fixed to one, the switch 24 may be omitted, and several types of load currents may be provided. In order to cope with this, the setting time of the timed circuit is provided by the number of times of switching, and at that time, the same number of switches 24 may be provided.

Embodiment 6 FIG. FIG. 8 is a circuit diagram showing a sixth embodiment of the present invention. As in the fifth embodiment, the transistor 16 outputs a timed signal for a predetermined time using the drive signal of the transistor 5 output from the control circuit 8 as a synchronization signal. It is turned on and off by the timed circuit 26. Reference numeral 25 denotes a coil 9 installed in the load circuit 13.
Is a load current detection circuit that detects the current of the load. The detection output of the load current detection circuit 25 is input to the time-limit circuit 26, and the time-limit circuit 26 outputs a pulse of a time corresponding to the detection output. That is, when the load current is small, a pulse with a short on-time is output, and when it is large, a pulse with a long on-time is output. Therefore, the current flowing from the commercial power supply 1 directly to the load circuit 13 is small when the on-time of the transistor 16 is short (small load current), and large when the on-time of the transistor 16 is long (large load current). . In this way, the pulsating current flowing through the load circuit is increased or decreased in accordance with the load current depending on the magnitude of the load current, so that the power factor is high, the generation of harmonics is small, and the ripple component of the load current is minimized. Can be smaller.

Embodiment 7 FIG. FIG. 9 is a circuit diagram showing a seventh embodiment of the present invention.
In this circuit configuration, the transistor 16 is omitted, the anode of the diode 17 is connected to the connection point between the coil 14 and the separation diode 15, and the cathode of the diode 17 is connected to the load circuit 13. This circuit is effective only in a narrow range of load conditions, that is, the optimum reactance value of the coil 14 is selected based on a specific load current value and the on / off frequency of the transistors 4 and 5 at that time, and is directly supplied from the commercial power supply 1. Load circuit 1
3. The high-frequency current flowing into 3 is reduced to one point. In this case, the ripple component of the load current may increase. However, if the load does not cause the ripple component to be a problem, the transistor 16 can be omitted, and the power supply harmonics can be reduced economically.

The operation of the seventh embodiment is such that when the transistor 5 is turned on, the coil 1 is switched from the commercial power supply 1 through the rectifier circuit 2.
4, a current flows through the loop of the diode 17, the discharge lamp 10, the coupling capacitor 12, and the transistor 5, and at the same time, a current also flows from the smoothing capacitor 3 to the loop of the coil 9, the discharge lamp 10, the coupling capacitor 12, and the transistor 5. When the transistor 5 is turned off and the transistor 4 is turned on, the diode 17 is reverse-biased by the back electromotive force generated in the coil 9 and the diode 17 is turned off. At this time, the electric charge stored in the coupling capacitor 12 is discharged to the discharge lamp 10 and the coil 9 as in the first embodiment.
And discharge in the loop of the transistor 4. Therefore, an alternating current flows through the load circuit 13, and a current that follows the voltage value flows from the commercial power supply 1.

Embodiment 8 FIG. FIG. 10 is a circuit diagram showing an eighth embodiment of the present invention.
Reference numeral 31 denotes a series-connected resistor provided between output terminals of the rectifier circuit 2, and reference numeral 32 denotes a control circuit that controls switching operations of the transistors 4, 5, and 16. FIG. 11 shows the control circuit 3
2 is a diagram showing the internal configuration of the circuit 2, in which 33 is an oscillation circuit, 34 is a frequency modulation circuit, and this frequency modulation circuit 34 is a resistor 30
, 31 and the oscillation output of the oscillation circuit 33, and outputs drive signals S1, S2, and S3 for the transistors 4, 5, and 16, respectively. FIG. 12 is a characteristic diagram showing an output characteristic of the frequency modulation circuit 34.
Switching drive signals S1, S2 and S3 for OUT
Represents the frequency fluctuation characteristics.

The operation of the eighth embodiment will be described with reference to the waveform diagram of FIG. FIG. 13A shows an output waveform of the rectifier circuit 2,
(B) is a characteristic diagram showing the switching frequency of the transistors 4, 5 and 16, and (c) is the ON / O of the transistor 4.
The FF waveform, (d) is the ON / OFF waveform of the transistor 5, and (e) is the ON / OFF waveform of the transistor 16.

The output voltage of the rectifier circuit 2 is a resistor 30 and a resistor 3
The voltage is divided by 1 and input to the control circuit 32. Control circuit 32
A frequency modulation circuit 34 modulates the oscillation output of the oscillation circuit 33 in accordance with the divided voltage VOUT. Frequency modulation circuit 34
As shown in FIG. 12, the output frequency becomes f2 when VOUT is 0 [V], and f1 when VOUT is the maximum Vp [V].
These frequencies have a relationship of f1> f2. Therefore, FIG.
As shown in FIGS. 3A and 3B, the switching frequency changes following the rectified waveform, and the switching frequency increases when the output voltage of the rectifier circuit 2 is high. Accordingly, as shown in FIGS. 13 (c), (d) and (e), the ON pulse width of each drive signal is narrow when the divided voltage is high so as to contradict the level of the divided voltage. It becomes wider when the voltage is low. Therefore, when the output voltage of the rectifier circuit 2 is high,
The step-up ratio with respect to the smoothing capacitor 3 is reduced and the load current is also reduced, so that the smoothing capacitor 3 and the transistors 4, 5 and 16 need only have low withstand voltages.

In the eighth embodiment, the instantaneous value of the AC voltage of the commercial power supply 1 is detected by the divided voltage of the resistor 30 and the resistor 31, but the secondary voltage is obtained by using a transformer instead of the resistor 30 and the resistor 31. The same effect can be obtained by detecting the instantaneous value.

Embodiment 9 FIG. FIG. 14 shows the configuration of another control circuit 32a, and 35 is a pulse width modulation circuit. FIG. 15 is a characteristic diagram for explaining the operation of the control circuit 32a, and FIG. 16 is a waveform diagram of a drive signal in each part of the inverter device having the control circuit 32a. Control circuit 32a of this embodiment
Is used in Example 8 (the circuit diagram of FIG. 10), the control circuit 3
In response to the drive signal of the predetermined frequency of the oscillation circuit 33 of the 2a, the pulse width modulation circuit 35 outputs the rectified circuit 2 when the divided voltage is high so as to be contrary to the level of the divided voltage VOUT as shown in FIG. In this case, the drive signal pulse width is narrow, and the drive signal pulse width is widened when the divided voltage is low.

FIG. 16A shows an output waveform of the rectifier circuit 2. This output voltage is divided by resistors 30 and 31 (VOU).
T), input to the control circuit 32a. In the control circuit 32a, the pulse width modulation circuit 35 performs pulse width modulation on the oscillation output of the oscillation circuit 33 based on this voltage. FIG. 16 (b)
Is a characteristic diagram in which the on-pulse width for switching the transistors 4, 5, and 16 is plotted in accordance with the passage of time of the rectified waveform. When the rectified voltage is high, the on-pulse width is narrowed. FIGS. 16 (c), (d) and (e) show ON / OFF states of the transistors 4, 5 and 16, respectively.
This is an OFF waveform. As described above, when the output voltage of the rectifier circuit 2 is high, the on-pulses of the transistors 4, 5, and 16 are controlled to be narrow, so that the boosting ratio with respect to the smoothing capacitor 3 is reduced and the load current is also reduced.
The smoothing capacitor 3 and the transistors 4, 5 and 16 need only have a low withstand voltage.

Embodiment 10 FIG. FIG. 17 is a circuit diagram showing Embodiment 10 of the present invention.
a and 10b are filaments of the discharge lamp 10, 36 is a transformer, 36a is a primary coil of the transformer 36, which is provided at the same position as the coil 14 of the first embodiment.
And 36c are the secondary coils. 37 and 38 are capacitors connected in series to the secondary coils 36b and 36c. Generally, the discharge lamp 10 is a filament 10
a, 10b, and the filaments 10a, 10b
After heating, a high pressure is applied between both filaments. This step of heating the filament is called preheating. Even when the discharge lamp 10 starts discharging, power must be continuously supplied to the filaments 10a and 10b. This aims at preventing the deterioration of the filaments 10a and 10b.

The primary coil 36a of the transformer 36 has the same function as the coil 14 of the first embodiment. That is, if the transistors 4, 5, and 16 are turned on / off by the drive signal from the control circuit 8, the primary coil of the transformer 36 is provided. A high-frequency current flows through the load circuit 13 through 36a, a back electromotive force is generated in the primary coil 36a, and a charging current flows through the diode 15 to the smoothing capacitor 3 with this voltage. On the other hand, 2
In the secondary coils 36b and 36c, a voltage several times the secondary / primary winding of the voltage of the primary coil 36a is induced, and this voltage is passed through the capacitor 37 to the filament 10a and the capacitor 38.
An electric current is supplied to the filament 10b through the wire. Therefore, 2
The number of turns of the secondary coils 36b and 36c is set to a value smaller than the number of turns of the primary coil 36a. As described above, since separate power can be easily supplied to the load circuit, the inverter device can be provided at low cost.

Embodiment 11 FIG. In the first embodiment, the cathode of the diode 17 is connected to the connection point between the coil 9 and the discharge lamp 10.
As shown in (5), the cathode of the diode 17 may be connected to the other end of the coil 9. In this case, a coupling capacitor 12a may be newly provided between the connection point and the smoothing capacitor 3.

Embodiment 12 FIG. FIG. 19 shows a twelfth embodiment of the present invention,
FIG. 3 is a circuit diagram in the case of turning on and off in synchronization with the transistor 4, wherein the coil 14 and the separation diode 15 are connected to the negative output terminal of the rectifier circuit 2. The voltage of the commercial power supply 1 is rectified by the rectifier circuit 2 and becomes a DC voltage (pulsating voltage).
The pulsating current output from the rectifier circuit 2 is separated from the separation diode 15,
The smoothing capacitor 3 is charged via the coil 14.

The control circuit 8 turns on and off the transistors 4 and 5 alternately, and simultaneously drives the transistor 16 with a signal synchronized with the transistor 4. When the transistor 4 and the transistor 16 are turned on by the drive signal of the control circuit 8, the transistor 4, the capacitor 12, the discharge lamp 10, the second current limiting
At the same time, a current flows from the rectifier circuit 2 to the path of the transistor 4, the capacitor 12, the discharge lamp 10, the diode 17, the transistor 16, and the coil 14 based on the instantaneous voltage of the pulsating voltage. These two currents charge the capacitor 12. Next, when the transistor 4 is turned off and the transistor 5 is turned on, the electric charge charged in the capacitor 12 is discharged via the coil 9, the discharge lamp 10 and the transistor 5. By repeating this operation, a high-frequency alternating current flows through the discharge lamp 10.

As described above, the high-frequency current flows through the load circuit 13 in accordance with the voltage of the commercial power supply 1, and the high-frequency component is eliminated by the capacitor 18 serving as a high-frequency removing filter. It approximates the voltage waveform of the power supply 1. When a high-frequency current flows through the coil 14, a back electromotive voltage is generated in the coil 14 (the polarity is opposite to that of the first embodiment in FIG. 1), and this voltage is applied to the smoothing capacitor 3 via the separating diode 15. Since the charging current flows, there is no current charged from the rectifier circuit 2 directly to the smoothing capacitor 3.

In the above description of the first to twelfth embodiments, MOS transistors are used as the first and second switching means.
It is possible to use an FET (field effect transistor) and omit the anti-parallel connected diode. Further, the configuration including the capacitor 18 has been described as the high-frequency removing filter. However, if a high-frequency removing filter including a coil and a capacitor is further added, a noise component output to the commercial power supply 1 can be reduced.

When a plurality of load circuits are connected in parallel, for example, with discharge lamps, the equivalent of the diode 17 in FIG. 1 is provided according to the number of loads, and the transistor 16 is connected to each load circuit. It is sufficient to provide a plurality of diodes 17 equivalent to one. In the case where only the diode 17 is used as in the seventh embodiment in FIG. 9, the diode may be provided in a number corresponding to the number of loads and connected to a corresponding portion of the load circuit.

[0056]

As described above, according to the first aspect of the present invention, a high-frequency current flows from the commercial power supply directly to the load circuit via the third switching means, and the capacitor is connected in parallel to the rectifier circuit. Since the high-frequency component is removed and the input current waveform approaches the input voltage waveform, there is an effect that the power factor is high, the generation of power supply harmonics is small, and a highly efficient device can be provided. Further, since the diode is provided between the third switching means and the load circuit, the third switching means has a low withstand voltage, and has an effect of reducing the cost of parts.

According to the second aspect of the present invention, the transformer for detecting the load current is provided, and the third voltage is detected by using the secondary voltage of the transformer.
Since the switching means is driven, a new signal generation part for driving the third switching means is not required, and the circuit is simple and economical.

According to the third aspect of the present invention, since the additional winding is provided in the second coil for current limitation in the load circuit and the third switching means is driven by the additional winding, the third switching means is provided. There is no need for a new signal generating portion or a new transformer for driving the circuit, and the circuit is simple and economical.

According to the fourth aspect of the present invention, the additional winding is provided in the preheating transformer for preheating the filament of the discharge lamp, and the third switching means is driven by the additional winding. There is no need for a new signal generation part for driving, and the circuit is simple and economical.

According to the fifth aspect of the present invention, since the third switching means is driven by the output of the timed circuit, the ratio of the current flowing from the commercial power supply directly to the load circuit to the current flowing from the smoothing capacitor to the load circuit is determined by the timed circuit. Can be set freely with the output pulse width of, and it is possible to reduce the ripple component of the load current with respect to various load currents, so that the power factor is high and the generation of power supply harmonics is reduced.

According to the invention of claim 6, a switch for changing the pulse width of the on-pulse output from the timed circuit is provided, and the pulsating current flowing through the load circuit can be increased or decreased by switching the switch. There is an effect that the power factor is high with respect to the load current and the generation of power supply harmonics is reduced.

According to the seventh aspect of the present invention, the pulse width of the on-pulse output from the timed circuit is set based on the detection output of the load current detection means, and even when the load current changes, the load circuit is automatically connected directly from the commercial power supply to the load circuit. Since the flowing current is kept at the optimum value, the ripple component of the load current can be reduced with respect to various load currents, and the power factor is high and the generation of power supply harmonics is reduced.

According to the eighth aspect of the invention, a high-frequency current flows from the commercial power supply directly to the load circuit via the diode,
The high frequency component is removed by the capacitor connected in parallel with the rectifier circuit, and the input current waveform approaches the input voltage waveform, resulting in a high power factor, low generation of power supply harmonics, and a simple circuit configuration, resulting in a low component cost. Has the effect of being inexpensive.

According to the ninth aspect of the present invention, the power factor is high, power supply harmonics are less generated, and power is separately supplied to the load circuit by a plurality of coils added to the first coil for boosting. Therefore, when the load is a discharge lamp, there is an effect that a power circuit for preheating the filament of the discharge lamp can be simply configured.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an inverter device according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram of a voltage, a current, and a drive signal in each part of the device.

FIG. 3 is a circuit diagram of an inverter device according to Embodiment 2 of the present invention.

FIG. 4 is a circuit diagram of an inverter device according to Embodiment 3 of the present invention.

FIG. 5 is a circuit diagram of an inverter device according to Embodiment 4 of the present invention.

FIG. 6 is a circuit diagram of an inverter device according to Embodiment 5 of the present invention.

FIG. 7 is a drive signal waveform diagram of the device.

FIG. 8 is a circuit diagram of an inverter device according to Embodiment 6 of the present invention.

FIG. 9 is a circuit diagram of an inverter device according to Embodiment 7 of the present invention.

FIG. 10 is a circuit diagram of an inverter device according to Embodiment 8 of the present invention.

FIG. 11 is a configuration diagram of a control circuit of the device.

FIG. 12 is a characteristic diagram for explaining the operation of the control circuit of the device.

FIG. 13 is a waveform diagram of a voltage, a current, and a drive signal in each part of the device.

FIG. 14 is a configuration diagram of a control circuit in an inverter device according to Embodiment 9 of the present invention.

FIG. 15 is a characteristic diagram for explaining the operation of the control circuit.

FIG. 16 is a waveform diagram of a voltage, a current, and a drive signal in each part of the device.

FIG. 17 is a circuit diagram of an inverter device according to Embodiment 10 of the present invention.

FIG. 18 is a circuit diagram of an inverter device according to Embodiment 11 of the present invention.

FIG. 19 is a circuit diagram of an inverter device according to Embodiment 12 of the present invention.

FIG. 20 is a circuit diagram of a conventional inverter device.

FIG. 21 is an input voltage and input current waveform diagram in a conventional inverter device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Commercial power supply 2 Rectifier circuit 3 Smoothing capacitor 4 First transistor 5 Second transistor 6 Diode 7 Diode 8 Control circuit 9 Second coil for current limiting 10 Discharge lamp 11 Capacitor 12 Coupling capacitor 13 Load circuit 14 For boosting 1st coil 15 Isolation diode 16 Third transistor 17 Diode 18 Capacitor 19 Transformer 20 Resistance 21 Transformer 22 Preheating transformer 23 Timed circuit 24 Switch 25 Load current detection circuit 26 Timed circuit 32 Control circuit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-38152 (JP, A) JP-A-5-38161 (JP, A) JP-A-5-64462 (JP, A) JP-A-4-38 193067 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02M 7/48 H02M 7/217 H05B 41/24

Claims (9)

(57) [Claims] 1. A rectifier circuit for rectifying an AC voltage to output a DC voltage, and first and second switching means provided between output terminals of the rectifier circuit and connected in series with each other and alternately turned on and off. A diode equivalently anti-parallel connected to each of the first and second switching means;
A control circuit for controlling on / off of the first and second switching means; a smoothing capacitor provided between the rectifier circuit and a series circuit of the first and second switching means; An inverter device comprising a connection point of the second switching means and a load circuit connected between the smoothing capacitor, a first boosting coil inserted between the rectifier circuit and the smoothing capacitor, A separation diode connected in series with the first boosting coil for separating the voltage of the rectifier circuit and the voltage of the smoothing capacitor, and a connection of a series circuit formed by the first boosting coil and the separation diode ; A first coil for boosting is connected between a point and the load circuit, and is controlled to be turned on / off in synchronization with either the first or second switching means. A third switching means for supplying a current flowing to the load circuit through the third switching means, and a third switching means connected in series with the third switching means, and
To prevent reverse voltage applied to switching means
Inverter apparatus characterized by comprising a de. 2. The flat circuit, which is inserted in series with the load circuit,
Detecting the current flowing from the smoothing capacitor to the load circuit
A transformer for driving the third switching means is provided;
The inverter device according to claim 1, wherein 3. The load circuit according to claim 1, wherein the load circuit is a discharge lamp,
The second coil of the transformer also serves as a transformer for detecting the load current.
3. The inverter device according to claim 2, wherein the inverter device is configured by an inverter. 4. The load circuit according to claim 1, wherein said load circuit is a discharge lamp,
Two coils and a coupling capacitor,
A connection point between the first and second switching means and the flat
Connected between the capacitor and the filament of the discharge lamp.
While subjected supplying power to bets, the third switching
Characterized in that a preheating transformer for driving the means is provided.
The inverter device according to claim 1 . 5. The first or second switching means.
Turns on synchronously and turns on pulse according to the value of the load current.
The third switching means during the on operation.
A timing circuit for driving the stage is provided.
2. The inverter device according to 1 . 6. An on-pulse width of said timed circuit is set.
6. The device according to claim 5, wherein a plurality of switches are provided.
On-board inverter device. 7. A method for detecting a current flowing through the load circuit,
Sets the on-pulse width of the timed circuit by the detection output of
Wherein the load current detecting means is provided.
The inverter device according to claim 5 or 6 . 8. A DC voltage is output by rectifying an AC voltage.
Provided between the rectifier circuit and the output terminal of the rectifier circuit,
First and second which are connected in series and turned on and off alternately.
Switching means and the first and second switching means
A diode equivalently anti-parallel connected to each of the means;
On / off control of the first and second switching means
A rectifying circuit and the first and second switches.
A smoothing capacitor provided between the switching means and
A connection point between the first and second switching means and the smoothing point;
With a load circuit connected between the capacitors
Data device, inserted between the rectifier circuit and the smoothing capacitor.
A first coil for boosting, and the first coil for boosting;
The voltage of the rectifier circuit and the smoothing capacitor connected in series
And a first diode for boosting the voltage.
The connection of the series circuit formed by the coil and the separation diode
Connected between the rectifier circuit and the load circuit
Of a current flowing through the load circuit through the first coil for
An inverter device comprising: a diode for performing electricity . 9. The load circuit includes a discharge lamp and a current limiting
Two coils and a coupling capacitor,
The booster first coil is provided on the first coil for boosting the discharge lamp.
The additional winding that supplies the filament power
Claims 1 to 3, and claims 5 to 8
The inverter device according to any one of the above .