JPH0731155A - Inverter - Google Patents

Abstract

PURPOSE:To suppress higher harmonics in a power supply by feeding high frequency current directly from the power supply to a load circuit through a switching means and removing the high frequency components through a capacitor connected in parallel with a rectifier circuit. CONSTITUTION:Pulsating current is fed from a rectifier circuit 2 through a coil 14 and an isolation diode 15 to a capacitor (CS) 3 which is thereby charged. When a transistor(Tr) 5 is turned ON by a drive signal delivered from a control circuit 8, the CS 3 is discharged to a load circuit 13 thus charging a CS 12. When a Tr 16 is turned ON in synchronism with a Tr 5, current flows from the rectifier circuit 2 through the coil 14, the Tr 16, a diode 17, a discharge lamp 10, the Cs 12 and the Tr 5. The current is combined with the current flowing from the CS 3 through a coil 9 and charges the CS 12. In other words, high frequency current flows depending on the voltage of the commercial power supply 1 and the high frequency component is eliminated by a capacitor 18.

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 and switching the DC voltage by turning on / off a switching means to supply high frequency power to a load.

[0002]

2. Description of the Related Art FIG. 20 shows, for example, JP-A-2-211065.
FIG. 1 is a circuit diagram of a conventional inverter device disclosed in Japanese Patent Laid-Open Publication No. H11-242, 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. 2 is applied to the transistors 4 and 5 which are switching means, and the control circuit 8 controls so that the transistors 4 and 5 are alternately turned on and off at high speed, and the high frequency power is current limited from the connection point of the transistors 4 and 5. For the second
It is supplied to the load (for example, a discharge lamp) via the coil 9 or the coupling capacitor 12. The diodes 6 and 7 are equivalently connected in anti-parallel to the transistors 4 and 5 for the purpose of flowing a regenerative current. Reference numeral 10 is a discharge lamp, 11 is a capacitor connected in parallel to the discharge lamp, and the second coil 9 for current limiting and this capacitor 11 constitute a resonance circuit, and a high voltage necessary for discharging is generated from both ends of the capacitor 11. The load circuit 13 of this inverter device is composed of a second coil 9 for limiting current, a discharge lamp 10, a capacitor 11 and a coupling capacitor 12.

The conventional inverter device is constructed as described above. First, when the transistor 5 is on and the transistor 4 is off, a current is unidirectionally applied from the smoothing capacitor 3 to the load circuit 13 via the transistor 5. This current flows and charges the coupling capacitor 12 in the load circuit 13. Then, when the transistor 5 is off and the transistor 4 is on, the charge of the coupling capacitor 12 is discharged through the transistor 4,
A current flows through the load circuit 13 in the opposite direction. Therefore, high frequency power is supplied to the 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 waveform, and the peak value is also high.

[0004]

Since the conventional inverter device is of the capacitor input type configured as described above, the input current waveform becomes a pulse-shaped sharp, which causes a problem of power factor reduction and harmonic interference. Has become.

The present invention has been made in order to solve such problems, and an object thereof is to obtain an inverter device which can reduce input distortion, has a high power factor, and has few harmonics.

[0006]

According to a first aspect of the present invention, an inverter device is provided between a rectifying circuit for rectifying an AC voltage and outputting a DC voltage, and an output terminal of the rectifying circuit, which are connected in series. First and second switching means that are turned on and off alternately, diodes that are equivalently connected in anti-parallel to each of the switching means, a control circuit that turns on and off the switching means, and the rectifier circuit And a smoothing capacitor provided between a series circuit of the switching means, and a load circuit connected between the connection point of the switching means and the smoothing capacitor, wherein the rectifying circuit and the smoothing capacitor are provided. A first coil for boosting inserted between the first coil and a first coil for boosting, which are connected in series with the first coil for boosting voltage and A separation diode that separates the voltage of the smoothing capacitor, a first coil for boosting, and a connection point between the series circuit of the separation diode and the load circuit, which are either the first or second switching means. Third switching means is provided which is driven on / off in synchronization with the crab and causes a current to flow from the rectifier circuit to the load circuit via the first coil for boosting.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, an inverter device is provided with a diode for blocking a reverse voltage applied to the third switching means in series with the third switching means. Is.

According to a third aspect of the present invention, in addition to the configuration of the first aspect, the inverter device is inserted in series with the load circuit and detects a current flowing from the smoothing capacitor to the load circuit to detect the third circuit. A transformer is provided to drive the switching means on and off.

According to a fourth aspect of the present invention, in addition to the configuration of the third aspect, the load circuit includes a discharge lamp,
It is composed of a second coil for current limitation and a coupling capacitor, and the second coil for current limitation is provided with a transformer which also serves to detect the load current.

According to a fifth aspect of the present invention, in addition to the configuration of the first aspect, the load circuit includes a discharge lamp,
It is composed of a second coil for current limiting and a coupling capacitor, is connected between the connection point of the first and second switching means and the smoothing capacitor, and supplies electric power to the filament of the discharge lamp, The third
The preheating transformer for driving the switching means of ON / OFF is provided.

According to a sixth aspect of the present invention, in addition to the configuration of the first aspect, the inverter device is turned on in synchronization with the first or second switching means, and has an on-pulse width corresponding to the value of the load current. During this on operation, the third
A time-limit circuit for driving the switching means of ON / OFF is provided.

According to a seventh aspect of the present invention, in addition to the configuration of the sixth aspect, the inverter device is provided with a plurality of switches for setting the pulse width of the on-pulse output from the time limit circuit.

According to an eighth aspect of the present invention, in addition to the configuration of the sixth aspect or the seventh aspect, the inverter device detects a current flowing in the load circuit, and outputs a pulse of an on-pulse output from the time limit circuit by the detection output. The load current detecting means for setting the width is provided.

According to a ninth aspect of the present invention, an inverter device is provided between a rectifying circuit that rectifies the AC voltage and outputs a DC voltage, and is provided between the output terminals of the rectifying circuit, connected in series with each other, and turned on alternately. First and second switching means for turning off, diodes equivalently connected in anti-parallel to each of the switching means, a control circuit for on / off controlling the switching means, a rectifying circuit and the switching means. In an inverter device provided with a smoothing capacitor provided between and a load circuit connected between the connection point of the switching means and the smoothing capacitor, a booster inserted between the rectifying circuit and the smoothing capacitor. Is connected in series with the first coil for boosting, the voltage of the rectifying circuit and the voltage of the smoothing capacitor. A separation diode for separation, a first coil for boosting, and a connection point of a series circuit of the separation diode and the load circuit, and the rectifier circuit through the first coil for boosting The load circuit is provided with a diode for passing a current.

According to a tenth aspect of the present invention, there is provided an inverter device according to any one of the first to ninth aspects.
A means for detecting the instantaneous value of the AC voltage and a control circuit for controlling the on / off frequencies of the first and second switching means by a voltage signal corresponding to the detected value of the detecting means are provided.

An inverter device according to an eleventh aspect of the present invention has the configuration according to any one of the first to ninth aspects,
A means for detecting the instantaneous value of the AC voltage and a control circuit for controlling the ON period of the first and second switching means by a voltage signal corresponding to the detected value of the detecting means are provided.

According to a twelfth aspect of the present invention, in addition to the configuration of any one of the first to fourth aspects or the sixth to eleventh aspects of the present invention, the load circuit includes a discharge lamp,
An additional winding wire, which is composed of a second coil for current limitation and a coupling capacitor, for supplying filament power of the discharge lamp is provided in the first coil for boosting.

[0018]

In the inverter device according to the first aspect of the present invention, the pulsating current output from the rectifying circuit is charged in the smoothing capacitor via the first coil for boosting and the separation diode, and the control is performed. The second switching means and the third switching means are simultaneously turned on by the drive signal of the circuit, and the current loop flowing through the load circuit based on the charging voltage of the smoothing capacitor and the first rectifying circuit for boosting the voltage. Two current loops that directly flow into the load circuit via the coil of the first switching means and the third switching means, and the first current for boosting is provided by the latter current.
A counter electromotive voltage is generated in the coil of
High-frequency current flows according to the voltage of the commercial power supply.

In the inverter device according to the second aspect of the present invention, the diode prevents the current from the second coil for current limiting from flowing to the third switching means, and the third switching means. The reverse voltage is prevented from being applied to.

In the inverter device according to a third aspect of the present invention, the transformer inserted in series with the load circuit detects the current flowing through the load circuit, and the secondary voltage of the transformer is used to detect the third voltage. Is switched on / off.

In the inverter device according to the fourth aspect of the present invention, when the load is a discharge lamp, the third switching means is turned on by the additional winding line of the second coil for current limitation which is indispensable for the load circuit.・ Driven off.

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

In the inverter device according to a sixth 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 synchronizing signal, and the output outputs the first signal. The switching means 3 is driven on / off.

In the inverter device according to the seventh aspect of the present invention, the pulse width of the ON pulse output from the time limit circuit is set by switching the switch corresponding to the current flowing in the load circuit.

In the inverter device according to claim 8 of the present invention, the current flowing through the load circuit is detected,
This detection output sets the pulse width of the on-pulse output from the time limit circuit.

In the inverter device according to claim 9 of the present invention, the pulsating current output from the rectifying circuit is charged in the smoothing capacitor via the first coil for boosting and the separating diode, and the control is performed. The drive signal of the circuit turns on the second switching means,
Two current loops that flow to the load circuit based on the charging voltage of the smoothing capacitor and two current loops that directly flow from the rectifier circuit to the load circuit via the boosting first coil and the diode are provided.

In the inverter device according to a tenth aspect of the present invention, the instantaneous value of the output voltage is detected, and the on / off frequencies of the first and second switching means are controlled in accordance with the instantaneous voltage value. It

In the inverter device according to the eleventh aspect of the present invention, the instantaneous value of the output voltage is detected, and the ON periods of the first and second switching means are controlled according to the instantaneous value of the voltage.

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

[0030]

EXAMPLES Example 1. 1 is a circuit diagram showing a first embodiment of the present invention, in which 1 to 13 are the same as those of 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 rectifying circuit 2 and the smoothing capacitor 3, and the coil 1 is further connected.
4 and the separation diode 15 in a series circuit, and a connection point between the second coil 9 for limiting current in the load circuit 13 and the discharge lamp 10 and a transistor 1 as a third switching means.
A series circuit of 6 and diode 17 is connected. Further, the capacitor 18 which plays the role of 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 a current waveform flowing in the coil 14, (d) is an ON / OFF waveform of the transistor 4 which is the first switching means,
(E) is the transistor 5 which is the second switching means
Is an ON / OFF waveform, and (f) is an ON / OFF waveform of the transistor 16 which is 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 source 1 shown in FIG. 2 (a) is rectified by the rectifier circuit 2, and the direct current voltage (pulsating current voltage) shown in FIG. 2 (b) is obtained.
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 coupled to the load circuit 13. The ring capacitor 12 is charged. 2 (d),
Since the transistor 4 and the transistor 5 are alternately turned on and off repeatedly as shown in (e), the transistor 5
Is turned off and the transistor 4 is turned on, the electric charge charged in the coupling capacitor 12 is discharged through 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 is repeatedly turned on and off in synchronization with the transistor 5 as shown in FIGS. 2 (e) and 2 (f). Therefore, when the transistor 16 is turned on, the output voltage of the rectifier circuit 2 is changed to the coil. 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 the waveform of the current flowing from the rectifier circuit 2 through the coil 14, and thus the high frequency current flows according to the voltage of the commercial power supply 1. This high-frequency current has no high-frequency component due to the capacitor 18 which functions as a high-frequency removal filter, and becomes an envelope current waveform having a waveform shown in FIG. 2C, and the input current waveform from the commercial power source 1 is a commercial waveform as shown in FIG. Power supply 1
Approaches the voltage waveform of. 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 counter electromotive voltage (boosting effect) is generated in the coil 14, and this voltage causes the separation diode 15
Since the charging current flows through the smoothing capacitor 3 via the, the current that directly charges the smoothing capacitor 3 from the rectifier circuit 2 disappears. As described above, since the input distortion can be reduced, it is possible to provide an inverter device having a high power factor and less generation of harmonics.

The coil 14 also serves to limit 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.
Prevents the current from the coil 9 from flowing to the transistor 16 and prevents a reverse voltage from being applied to the transistor 16, which has the effect of lowering the breakdown voltage of the transistor 16. Although transistors are used as the switching means of the transistors 4, 5 and 16, MOS FET
The same effect can be obtained by using other switching elements such as (field effect transistor).

Example 2. FIG. 3 is a circuit diagram showing a second embodiment of the present invention, and 1 to 18 are exactly the same as the first embodiment. Reference numeral 19 is a transformer whose primary side is connected to the inside of the load circuit 13. The secondary side of the transformer 19 is connected to the base terminal of the transistor 16 via the resistor 20.

The transistor 4 and the transistor 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 is passed through the coil 9, the primary side of the transformer 19, the discharge lamp 10 and the transistor 5. Flows,
This current is indicated by an arrow I in FIG. 3 on the primary side of the transformer 19.
Flow in the direction shown in 1. Then, on the secondary side of the transformer 19, a current flows in the direction indicated by the arrow I2 and the transistor 16
Turn on. When 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.

Example 3. FIG. 4 is a circuit diagram showing a third embodiment of the present invention, in which the transformer 21 is connected to the load circuit 13 in place of the coil 9 of the first embodiment. Transformer 21
Primary side of the discharge lamp 1 and the high potential side of the smoothing capacitor 3
The winding connected between 0 plays a role similar to that of the coil 9 of the conventional device or the first embodiment, and when the transistor 5 is turned on, a current flows through the primary side of the transformer 21, and the secondary current of the transformer 21 causes the transistor to flow. 16 turns on. When 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.

Example 4. FIG. 5 is a circuit diagram showing Embodiment 4 of the present invention, in which 22 is a preheating transformer,
The primary side of 2 is inserted between the connection point of the transistors 4 and 5 and the smoothing capacitor 3, and the secondary side is provided with three coils, and the coils A and B are respectively connected to the filament of the discharge lamp 10 and the coil C. Is connected to the transistor 16.

The transistors 4 and 5 are alternately turned on and off in the same manner as in the first embodiment to apply high-frequency power to the load circuit 13 and, at the same time, through the preheating transformer 22.
Preheat power to the filament. At this time, the transistor 16 is driven by the secondary coil C of the preheating transformer 22, a high frequency current flows directly from the commercial power source 1 to the load circuit 13 as in the first embodiment, and a counter electromotive force is generated in the coil 14. With this voltage, a charging current flows through the smoothing capacitor 3 via the separation diode 15. This eliminates the current that directly charges the smoothing capacitor 3 from the rectifier circuit 2. The polarity of the secondary coil of the preheating transformer 22 is connected so that the voltage generated when the transistor 5 is on turns on the transistor 16. In this way, when the load is a discharge lamp, the preheating transformer 22 that preheats the discharge lamp can be used to drive the newly provided transistor 16 to reduce the distortion of the input current.

Example 5. FIG. 6 is a circuit diagram showing a fifth embodiment of the present invention. The fifth embodiment is basically the same as the first embodiment, but the driving method of the transistor 16 is different. That is, a time limit circuit 23 that outputs a time limit signal for a predetermined time using the drive signal of the transistor 5 that is an output from the control circuit 8 as a synchronization signal, and a switch 24 that switches the pulse width of the time limit signal of the time limit circuit 23 are provided. The output of 23 drives the transistor 16 on / off.

The operation of the fifth embodiment will be described with reference to the waveform chart of FIG. FIG. 7A shows that the transistor 4 is ON / OFF.
Waveform, (b) ON / OFF waveform of the transistor 5,
(C) is an ON / OFF waveform of the transistor 16.
The drive signal of the transistor 5 which is the output of the control circuit 8 causes the time circuit 23 to operate. When the switch 24 is closed, an on-pulse of t1 time is output, and when the switch 24 is open, an on-pulse of t2 time is output. To do. The output of the time limit circuit 23 drives the transistor 16 to turn 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 becomes small. This is because the impedance of the coil 9 increases.
Further, the ratio of the pulsating current flowing from the output of the rectifier circuit 2 directly to the load circuit 13 via the transistor 16 and the direct current flowing from the smoothing capacitor 3 via the coil 9 may be the ripple component of the load current as it is. It's clear. Therefore, when the ON / OFF repetition frequency of the transistors 4 and 5 is increased and the load current is decreased, the ripple current increases. Therefore, the switch 24 is closed when the load current is set small, and the switch 24 is opened when the load current is set large. As a result, when the load current is set small, the pulsating current becomes small because the ON time of the transistor 16 is short, and when the load current is set large, the ON time of the transistor 16 becomes long and the pulsating current also becomes large.

When the load current is set large, the reason why the pulsating current is increased is that the electric charge accumulated in the smoothing capacitor 3 uses the counter electromotive voltage generated in the coil 14, so that the smoothing capacitor 3 transfers to the load circuit 13. This is because it is necessary to increase the high frequency current flowing through the coil 14 when a large amount of current is passed. Conversely, smoothing capacitor 3 to load circuit 1
When the current supplied 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 according to 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 handle two types of load currents. However, if the load current is fixed to one, the switch 24 may be omitted, and several types of load currents may be omitted. In order to correspond to the above, it is sufficient to provide the set time of the time circuit by the number of times of switching, and at that time, provide the same number of switches 24.

Example 6. FIG. 8 is a circuit diagram showing a sixth embodiment of the present invention. As with the fifth embodiment, the transistor 16 outputs a timed signal for a predetermined time by using the drive signal of the transistor 5 which is the output from the control circuit 8 as a synchronizing signal. It is driven on / off by the time limit circuit 26. 25 is a load circuit 1
3 is a load current detection circuit that is installed in the circuit 3 and detects the current of the coil 9. 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 the pulse of the time corresponding to this detection output. That is, when the load current is small, a pulse with a short ON time is output, and conversely, when the load current is large, a pulse with a long ON time is output. Therefore, the current flowing directly from the commercial power source 1 to the load circuit 13 is small when the on-time of the transistor 16 is short (the load current is small) and large when the on-time of the transistor 16 is long (the load current is large). . In this way, in order to increase or decrease the pulsating current flowing through the load circuit according to the load current depending on the magnitude of the load current, the power factor is high and the generation of harmonics is small.
Moreover, the ripple component of the load current can be minimized.

Example 7. FIG. 9 is a circuit diagram showing a seventh embodiment of the present invention, in which the transistor 16 of the first embodiment is omitted, the anode of the diode 17 is at the connection point between the coil 14 and the separation diode 15, and the cathode of the diode 17 is It 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 according to the specific load current value and the on / off frequencies of the transistors 4 and 5 at that time, and the commercial power source 1
The high frequency current flowing directly into the load circuit 13 is narrowed down to one point. In this case, the ripple component of the load current may increase, but if the load does not cause a ripple component, the transistor 1
Since 6 can be omitted, power supply harmonics can be economically reduced.

The operation of the seventh embodiment is such that when the transistor 5 is on, the coil 1 is fed from the commercial power source 1 via 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 flows from the smoothing capacitor 3 to the coil 9, the discharge lamp 10, the coupling capacitor 12 and the loop of the transistor 5. When the transistor 5 is turned off and the transistor 4 is turned on, the counter electromotive force generated in the coil 9 causes the diode 17 to be reverse biased and the diode 17 is turned off. At this time, as in the first embodiment, the electric charge accumulated in the coupling capacitor 12 is the discharge lamp 10 and the coil 9.
And is discharged 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.

Example 8. FIG. 10 is a circuit diagram showing an eighth embodiment of the present invention, where 30 and 31 are resistors connected in series between the output terminals of the rectifier circuit 2, 32 is a transistor 4,
5 is a control circuit for controlling the switching operations of 5 and 16. FIG. 11 shows an internal configuration diagram of the control circuit 32.
Reference numeral 33 is an oscillation circuit, 34 is a frequency modulation circuit, and this frequency modulation circuit 34 is a voltage VOU divided by resistors 30 and 31.
T and the oscillation output of the oscillation circuit 33 are input and drive signals S1, S2 and S3 for the transistors 4, 5 and 16 are output, respectively. FIG. 12 is a characteristic diagram showing the output characteristic of the frequency modulation circuit 34 and shows the frequency variation characteristic of the switching drive signals S1, S2 and S3 with respect to the divided voltage VOUT.

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

The output voltage of the rectifier circuit 2 is the resistance 30 and the resistance 3.
The voltage is divided by 1 and input to the control circuit 32. Control circuit 32
The frequency modulation circuit 34 therein modulates the oscillation output of the oscillation circuit 33 according to the divided voltage VOUT. Frequency modulation circuit 34
As shown in FIG. 12, the output frequency of is f2 when VOUT is 0 [V] and f1 when VOUT is maximum Vp [V],
These frequencies have a relationship of f1> f2. Therefore, FIG.
3 (a) and 3 (b), 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. 13C, 13D, and 13E, the ON pulse width of each drive signal is narrow when the divided voltage is high so as to be opposite to the high or low of the divided voltage. Widens when the voltage is low. Therefore, when the output voltage of the rectifier circuit 2 is high,
The step-up ratio to the smoothing capacitor 3 is reduced and the load current is also suppressed to be small, so that the smoothing capacitor 3 and the transistors 4, 5 and 16 have low withstand voltage.

In the eighth embodiment, the instantaneous value of the AC voltage of the commercial power source 1 is detected by the divided voltage of the resistors 30 and 31, but a transformer is used instead of the resistors 30 and 31, and the secondary voltage thereof is used. Even if the instantaneous value is detected, the same effect can be obtained.

Example 9. FIG. 14 shows another control circuit 3
The structure of 2a is shown, 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. When the control circuit 32a of this embodiment is used in the eighth embodiment (circuit diagram of FIG. 10), the pulse width modulation circuit 35 shown in FIG. 15 is provided for the drive signal of the predetermined frequency of the oscillation circuit 33 of the control circuit 32a. The drive signal pulse width is narrowed when the divided voltage is high and widened when the divided voltage is low so that the divided voltage VOUT of the output voltage of the rectifier circuit 2 is opposite to the level of the divided voltage VOUT.

FIG. 16 (a) shows the output waveform of the rectifier circuit 2. This output voltage is divided by resistors 30 and 31 (VOU
T), and 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. Figure 16 (b)
Shows a characteristic diagram of the on-pulse width for switching the transistors 4, 5 and 16 according to the passage of time of the rectified waveform, and shows that the on-pulse width is narrowed when the rectified voltage is high. 16C, 16D, and 16E show ON / OFF of the transistors 4, 5 and 16, respectively.
It is an OFF waveform. In this way, 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 step-up ratio for the smoothing capacitor 3 is reduced and the load current is also reduced.
The smoothing capacitor 3 and the transistors 4, 5 and 16 may have a low withstand voltage.

Example 10. FIG. 17 is a tenth embodiment of the present invention.
FIG. 10 is a circuit diagram showing a coil 10a and 10b, a filament of the discharge lamp 10, a transformer 36, and a primary coil 36a of the transformer 36, which are provided at the same positions as the coil 14 of the first embodiment. Is its secondary coil. 37 and 38 are secondary coils 36b and 36c.
Is a capacitor connected in series with. Generally, the discharge lamp 10 applies electric power to the filaments 10a and 10b, heats the filaments 10a and 10b, and then applies a high voltage between both filaments. The process of heating this filament is called preheating. Further, even if the discharge lamp 10 starts discharging, electric power must be continuously applied to the filaments 10a and 10b. This is the filament 10a, 10
The purpose is to prevent deterioration of b.

The primary coil 36a of the transformer 36 has the same function as that of 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 turned on. A high frequency current flows through the load circuit 13 through 36a, a counter electromotive force is generated in the primary coil 36a, and a charging current flows through the smoothing capacitor 3 via the diode 15 at this voltage. On the other hand, transformer 36-2
In the secondary coils 36b and 36c, a voltage which is a multiple of the secondary / primary winding of the voltage of the primary coil 36a is induced, and this voltage is transmitted via the capacitor 37 to the filament 10a and the capacitor 38.
An electric current is passed through the filament 10b via the. Therefore, 2
The number of windings of the secondary coils 36b and 36c is set to a value smaller than the number of windings of the primary coil 36a. In this way, since separate power can be easily supplied to the load circuit, the inverter device can be provided at low cost.

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

Example 12 FIG. 19 shows a twelfth embodiment of the present invention.
Is a circuit diagram when the transistor 16 is turned on / off in synchronization with the transistor 4, and 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 to become a DC voltage (pulsating voltage), and the pulsating current output from the rectifying circuit 2 charges the smoothing capacitor 3 via the separation diode 15 and the coil 14.

The control circuit 8 alternately turns on and off the transistors 4 and 5, and at the same time drives the transistor 16 with a signal synchronized with the transistor 4. If 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, and the second current limiting second capacitor are charged based on the charging voltage of the smoothing capacitor 3.
A current flows through the coil 9, and at the same time, a current also flows from the rectifier circuit 2 through the paths 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. Both 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 to the load circuit 13 in response to the voltage of the commercial power source 1, the high frequency component is eliminated by the capacitor 18 which functions as a high frequency removing filter, and the input current waveform from the commercial power source 1 is commercial. It is approximated to the voltage waveform of the power supply 1. Further, when a high frequency current flows through the coil 14, a counter electromotive voltage is generated in the coil 14 (the polarity is opposite to that in the first embodiment of FIG. 1), and this voltage causes the smoothing capacitor 3 to pass through the separation diode 15 to the smoothing capacitor 3. Since the charging current flows, the current charged from the rectifying circuit 2 directly to the smoothing capacitor 3 disappears.

In the above description of the first to twelfth embodiments, MOS is used as the first and second switching means.
It is possible to use a FET (Field Effect Transistor) and omit the diode in anti-parallel connection. Further, although the configuration including the capacitor 18 as the high frequency removing filter is shown, the noise component output to the commercial power source 1 side can be reduced by further adding the high frequency removing filter including the coil and the capacitor.

When a plurality of load circuits are connected in parallel such as discharge lamps, the diodes 17 of FIG. 1 are provided in accordance with the number of each load, and if the load circuit is connected to each load circuit, the transistor 16 can be connected. It suffices that one is provided and a plurality of diodes 17 are provided. Also, in the case where only the diode 17 is used as in the seventh embodiment shown in FIG. 9, as many diodes as the number of loads may be provided and connected to the corresponding portions of the load circuit.

[0062]

As described above, according to the invention of claim 1, a high frequency current flows from the commercial power source directly to the load circuit via the third switching means, and the capacitor connected in parallel to the rectifier circuit is used. Since the high frequency component is removed and the input current waveform approaches the input voltage waveform, there is an effect that it is possible to provide a device with high power factor, less generation of power source harmonics, and high efficiency.

According to the invention of claim 2, since the diode is provided between the third switching means and the load circuit, in addition to the effect of the invention of claim 1, the withstand voltage of the third switching means is low. This has the effect of reducing the cost of parts.

According to the invention of claim 3, since a transformer for detecting a load current is provided and the third switching means is driven by using the secondary voltage of this transformer, in addition to the effect of the invention of claim 1, There is an effect that a new signal generating portion for driving the third switching means is unnecessary and the circuit is simple and economical.

According to the invention of claim 4, an additional winding is provided in the second coil for limiting the current in the load circuit, and the third switching means is driven by this additional winding. In addition to the effect of the present invention, there is an effect that a new signal generating portion or a new transformer for driving the third switching means is not required, and the circuit is simple and economical.

According to the invention of claim 5, an additional winding wire is provided in the preheating transformer for preheating the filament of the discharge lamp, and the third winding means is driven by this additional winding wire. Therefore, according to the invention of claim 1, In addition to the effects, there is an effect that a new signal generating portion for driving the third switching means is unnecessary and the circuit is simple and economical.

According to the sixth aspect of the present invention, since the third switching means is driven by the output of the time limit circuit, the ratio of the current flowing from the commercial power source directly to the load circuit and the current flowing from the smoothing capacitor to the load circuit is determined by the time limit circuit. Since the output pulse width can be set freely, the ripple component of the load current can be reduced for various load currents, the power factor is high, and the power supply harmonics are less likely to occur.

According to the invention of claim 7, a switch for changing the pulse width of the on-pulse output from the time circuit is provided, and the pulsating current flowing through the load circuit can be increased or decreased by switching the switch. With respect to the load current of 1, the power factor is high and the generation of power source harmonics is reduced.

According to the eighth aspect of the present invention, the pulse width of the on-pulse output from the time circuit is set by the detection output of the load current detection means, and even if the load current changes, the commercial power source automatically changes the load circuit directly to the load circuit. Since the flowing current is maintained at the optimum value, the ripple component of the load current can be reduced for various load currents, and the power factor is high and the generation of power supply harmonics is reduced.

According to the ninth aspect of the invention, the high frequency current flows from the commercial power source directly to the load circuit via the diode,
High frequency components are removed by a capacitor connected in parallel with the rectifier circuit, and the input current waveform approaches the input voltage waveform, resulting in a high power factor, less generation of power source harmonics, and a simple circuit configuration, resulting in low component cost. Has the effect of being cheap.

According to the tenth or eleventh aspect of the invention, the power factor is high, the generation of power source harmonics is small, and the ON pulse of the switching means is controlled to be narrow when the instantaneous value of the output voltage of the rectifier circuit is high. Therefore, the step-up ratio to the smoothing capacitor is reduced, the load current is also suppressed to be small, and the withstand voltage of the smoothing capacitor and the switching means can be lowered.

According to the twelfth aspect of the invention, the power factor is high,
The generation of power supply harmonics is small, and the power is supplied separately to the load circuit by the multiple coils added to the first coil for boosting. Therefore, when the load is a discharge lamp, the power to preheat the filament of the discharge lamp. There is an effect that the circuit can be easily configured.

[Brief description of 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 voltage, current and drive signal in each part of the device.

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

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

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

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

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

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

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

FIG. 10 is a circuit diagram of an inverter device according to an eighth embodiment 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 voltage, current, and drive signal in each part of the device.

FIG. 14 is a configuration diagram of an inverter device control circuit according to a ninth embodiment 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 voltage, current, and drive signal in each part of the device.

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

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

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

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

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

[Explanation 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 Boosting First coil 15 isolation diode 16 third transistor 17 diode 18 capacitor 19 transformer 20 resistor 21 transformer 22 preheating transformer 23 time circuit 24 switch 25 load current detection circuit 26 time circuit 32 control circuit

Claims (12)

[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, which are connected in series with each other and which are alternately turned on and off. A diode equivalently connected in anti-parallel 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 including a connection point of the second switching means and a load circuit connected between the smoothing capacitors, and a first coil for boosting inserted between the rectifier circuit and the smoothing capacitors,
A separation diode that is connected in series with the boosting first coil and separates the voltage of the rectifier circuit from the voltage of the smoothing capacitor, and a connection point of the series circuit of the boosting first coil and the separation diode. Connected between the load circuit and the load circuit, ON / OFF controlled in synchronization with either the first or second switching means, and the load circuit from the rectifier circuit via the first coil for boosting. An inverter device, characterized in that a third switching means for flowing a current is provided. 2. The inverter device according to claim 1, further comprising a diode that blocks a reverse voltage applied to the third switching means in series with the third switching means. 3. A transformer provided in series with the load circuit for detecting a current flowing from the smoothing capacitor to the load circuit to drive the third switching means. Inverter device. 4. The load circuit includes a discharge lamp, a second coil for limiting current, and a coupling capacitor,
The inverter device according to claim 3, wherein the second coil for current limitation is configured by a transformer that also serves to detect the load current. 5. The load circuit includes a discharge lamp, a second coil for limiting current, and a coupling capacitor,
A preheating transformer is provided, which is connected between the connection point of the first and second switching means and the smoothing capacitor, supplies electric power to the filament of the discharge lamp, and drives the third switching means. The inverter device according to claim 1, which is characterized in that. 6. A timed circuit which turns on in synchronism with the first or second switching means, changes the on-pulse width in accordance with the value of the load current, and drives the third switching means during the on-operation. 3. The method according to claim 1, further comprising:
Inverter device described. 7. The inverter device according to claim 6, further comprising a plurality of switches for setting an ON pulse width of the time limit circuit. 8. The inverter according to claim 6, further comprising load current detection means for detecting a current flowing through the load circuit and setting an ON pulse width of the time limit circuit based on the detected output. apparatus. 9. A rectifying circuit for rectifying the AC voltage and outputting a DC voltage, and first and second switching means provided between output terminals of the rectifying circuit and connected in series with each other to alternately turn on and off. A diode equivalently connected in anti-parallel to each of the first and second switching means, a control circuit for on / off controlling the first and second switching means, the rectifying circuit and the first and second switching means. An inverter device comprising: a smoothing capacitor provided between 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 a rectifying circuit and the smoothing capacitor, and a first coil for boosting are connected in series, and the voltage of the rectifying circuit and the smoothing capacitor are connected. A separation diode that separates the voltage of the capacitor, a first coil for boosting, and a connection point between a series circuit of the separation diode and the load circuit, and the first coil for boosting from the rectification circuit. An inverter device characterized in that a diode is provided to allow a current to flow through the load circuit via the inverter. 10. A means for detecting the instantaneous value of the AC voltage, and a control circuit for controlling the on / off frequencies of the first and second switching means by a voltage signal corresponding to the detected value of the detecting means are provided. Claim 1 characterized by the above.
The inverter device according to claim 9. 11. A means for detecting the instantaneous value of the AC voltage, and a control circuit for controlling the ON period of the first and second switching means by a voltage signal corresponding to the detected value of the detecting means are provided. The inverter device according to any one of claims 1 to 9, characterized in that. 12. The load circuit includes a discharge lamp, a second coil for limiting current, and a coupling capacitor, is provided in the first coil for boosting, and supplies the filament power of the discharge lamp. A winding device is provided, The inverter apparatus in any one of Claim 1 thru | or 4 or Claim 6 thru | or 11 characterized by the above-mentioned.