JP3417112B2 - Inverter device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a chopper section and an inverter section, wherein the chopper switching element of the chopper section also serves as one inverter switching element of the inverter section, and a feedback section is provided to provide an inverter section. The present invention relates to an inverter device in which an alternating output is fed back to each switching element to control ON / OFF of the switching element.

[0002]

2. Description of the Related Art Conventionally, a chopper section and an inverter section are provided, and a switching element for the chopper of the chopper section is also used as a switching element for one inverter of the inverter section, and a feedback section is provided to provide an alternating output of the inverter section. the fed back to the switching element inverter apparatus that performs on-off control of the switching elements, there is shown in FIG. 10.

Chopper section 1 in this inverter device
Is a switching element Q ₂ for a chopper and an AC power supply A
A capacitor C ₁ and a diode D ₅ connected in parallel between the output terminals of a diode bridge DB that rectifies the output of C;
An inductor L ₁ and a diode D ₆ connected in series to one output end of the diode bridge DB and one end of the switching element Q ₂ and a capacitor C ₀ connected in parallel to the series circuit of the switching elements Q ₁ and Q _2. The diode output of the diode bridge DB is provided to the switching element Q ₂
The voltage is boosted by intermittently connecting at, and the obtained DC output is supplied to the inverter unit 2'of the next stage.

On the other hand, the inverter section 2 ', the two inverter switching elements Q _1, Q ₂ are connected in series between the output end of the chopper section 1 (across the capacitor C _0), the two switching devices Q _1, By alternately turning on and off Q ₂ , the DC output supplied from the chopper unit 1 is converted into an alternating output and supplied to the discharge lamp La which is a load.
That is, the also serves two switching elements Q _1, the switching element Q ₂ one of Q _{2 'in} the inverter switching elements in the chopper switching element and an inverter section 2' of the chopper unit 1. Further, in the inverter unit 2 ', the discharge lamp La
One end of the primary winding n of the current transformer CT, which is a feedback section, is connected to one of the filaments through the inductor L _2, and the other end of the primary winding n is connected to two switching elements Q ₁ and Q ₂ . Connect to the point, current transformer CT
Two secondary windings n ₁ and n ₂ are connected to switching elements Q ₁ and Q ₂ via resistors R ₁ and R ₂ , respectively, and are induced in the secondary windings n ₁ and n _2. returned an alternating output to the switching element Q _1, Q _2, has a so-called self-excited to control the on-off time of the switching element Q _1, Q ₂ in accordance with the feedback amount.

The operation of the above-mentioned inverter device will now be described. When the switching element Q ₂ is on and the switching element Q ₁ is off, the path of capacitor C ₁ → inductor L ₁ → diode D ₆ → switching element Q ₂ Then, a current flows (see solid line C in the figure), and this current causes energy to be stored in the inductor L ₁ . Then, the energy stored in the inductor L ₁ is released when the switching element Q ₁ is turned on and the switching element Q ₂ is turned off, and the inductor L ₁ → switching element Q ₁ →
Capacitor C ₀ → capacitor C _{1 in} the path
By charging ₀ , the voltage is boosted to a predetermined voltage, and the chopper unit 1 constitutes a so-called boost chopper circuit.

On the other hand, when the switching element Q ₂ is on and the switching element Q ₁ is off, the capacitor C ₀ of the chopper section 1 → the capacitor C ₃ → the discharge lamp La → the inductor L ₂ → the primary winding n of the current transformer CT. → A current flows through the path of the switching element Q ₂ (see solid line A in the figure). When the current flowing through the primary winding n of the current transformer CT exceeds a predetermined value, the switching element Q ₂ turns off and the switching element Q ₁ turns on, and the energy stored in the inductor L ₂ is released. By doing so, inductor L ₂ → discharge lamp La → capacitor C ₃
→ Switching element Q ₁ → Current flows through the path of the primary winding n of the current transformer CT (see the solid line B in the figure), and a substantially sinusoidal alternating current is supplied to the discharge lamp La which is a load.

[0007]

By the way, in the above-mentioned conventional structure, the feedback amounts fed back to the _two switching elements Q ₁ and Q ₂ via the current transformer CT are substantially the same. That is, since the two secondary windings n ₁ and n _{2 have} the same number of turns, the two switching elements Q ₁ and Q 2
The level of the control signal given to ₂ is always the same,
The ON times of the _two switching elements Q ₁ and Q ₂ are also substantially the same, and balanced control is performed. However, when the light load is connected between the output terminals of the inverter unit 2 ′ or the power consumption in the load is reduced such as when the output terminals are short-circuited, the surplus power is charged in the capacitor C ₀ and the capacitor C ₀ is charged. There is a problem that the voltage across both ends of ₀ (DC output voltage of the chopper section 1) becomes unnecessarily high, and an overvoltage is applied to the switching elements Q ₁ and Q ₂ and the load, sometimes damaging the circuit element and the load. It was

An object of the present invention is to solve the above problems, and an object of the present invention is to provide an inverter device capable of suppressing an increase in output at the time of a light load or a short circuit with a simple structure.

[0009]

In order to achieve the above object, the invention of claim 1 is provided with a chopper portion having a chopper switching element for connecting and disconnecting a DC power source, and a plurality of inverter switching elements. An inverter section that alternately turns on and off the switching elements for the inverter to convert the output of the chopper section into alternating electric power and output it.
It is provided with a feedback unit that feeds back the alternating output of the inverter unit and controls ON / OFF of each inverter switching element,
In the inverter apparatus comprising also serves as a chopper switching element of the chopper unit and one inverter switching element of the inverter, detects the DC output Cho Tsu path portion
At least one inverter from the output detector and the return unit
In the feedback loop of the alternating output to the switching element for
The impedance variable part that changes the impedance
The impedance variable part is equipped with a chopper by the detection part.
If the rise of the DC output of the
Switching for choppers by reducing speed
The switching element for the inverter that is also used as the element
It is characterized by shortening the operating time .

According to a second aspect of the invention, in the first aspect of the invention, a discharge lamp having a filament is used as a load,
Preheat current to preheat the filament before starting
It is characterized by being supplied from an inverter unit .

[0011]

According to the structure of the invention of claim 1, the direct current of the chopper portion is
At least one of a detection unit for detecting the output and a feedback unit
Alternate output feedback loop to inverter switching element
Impedance that varies the impedance in the
The variable impedance section is provided by the detecting section.
If an increase in the DC output of the chopper is detected, the feedback loop
Switch impedance for the chopper
Inverter switching that is also used as a switching element
A light load was connected because the on time of the element was shortened .
The DC output of the chopper section due to a short circuit between the output terminals, etc.
If it constantly rises, such an abnormal rise in DC output
Detected by the detection unit, and changed by the impedance variable unit.
Inverter switch that doubles as a switching element for the inverter
The on-time of the switching element should be shorter than in the normal state.
The increase in the DC output of the chopper can be suppressed by and
In comparison, the circuit configuration is simple and the output rise is suppressed in the event of an abnormality.
The road can be protected.

According to the second aspect of the invention, the filament
Load the discharge lamp with a
The preheating current for preheating the components from the inverter
Since it is supplied, it has a special preheating circuit configuration.
Preheat current can be supplied to the filament without
The circuit configuration can be simplified.

[0013]

EXAMPLES In each of the following examples, a discharge lamp lighting device using a discharge lamp La as a load will be described as an example. However, the load is not limited to the discharge lamp La, and the switching of the chopper section and the inverter section is possible. It goes without saying that the technical idea of the present invention can be applied to general inverter devices that also serve as elements.

(First Embodiment) FIG. 1 is a circuit diagram showing a first embodiment of the present invention. Figure 1
As shown in FIG. 5, the basic configuration of the present embodiment is common to that described in the conventional example, the common portions are denoted by the same reference numerals, and the description thereof will be omitted. Only the characteristic features of the present embodiment will be described. explain.

In the present embodiment, an impedance variable section 3 for varying the impedance in the feedback loop of the control signal from the secondary winding n ₂ of the current transformer CT, which is the feedback section, to the switching element Q ₂ on the shared side is provided. By changing the impedance of the feedback loop in the impedance variable section 3, two switching elements Q ₁ , Q ₂
A series circuit of resistors R ₇ and R ₈ as a detection unit for detecting the DC output of the chopper unit 1 is provided. It is characterized in that the impedance variable section 3 changes the impedance according to the detection outputs detected by R ₇ and R ₈ .

In the variable impedance section 3, a Zener diode ZD is connected to the connection point of the resistors R ₇ and R ₈ connected in parallel with the series circuit of the switching elements Q ₁ and Q _2.
The base of the transistor Q ₅ is connected via ₅ ,
The transistor Q ₅ turns on when the voltage across the resistor R ₈ rises and exceeds the Zener voltage of the Zener diode ZD _{5 in} the event of an abnormality such as a connection of a light load or a short circuit. Further, the collector of the transistor Q ₅ is connected to the base of the transistor Q ₄ , and when the transistor Q ₅ is turned on, the transistor Q ₄ is biased and turned on.

On the other hand, the secondary winding n of the current transformer CT
₂ and the resistor R ₂ is inserted between the switching element Q _3, in a normal state, as shown in FIG. 2 (a),
A switching element Q ₂ on-time t ₂ and the on-time t ₁ of the switching element Q ₁ is set so as to be substantially the same. The resistor R ₂ connected in parallel with the resistor R _2
3 series circuit of the transistor Q ₄ and the resistor R ₄ is is connected in parallel. The resistance R ₂ of one end transistor Q ₃ between the one end of the switching element Q ₂ is Yes connected, the resistor R ₃ to the base of the transistor Q _3, R
₄ are connected in parallel, and a capacitor C ₅ is connected between the base and the emitter. In the normal output state, the transistor Q ₃ is turned off because of the time constant of the resistor R ₃ and the capacitor C ₅ .

Next, the operation when the DC output of the chopper section 1 rises due to the occurrence of an abnormality such as a light load or a short circuit will be described. First, increase the DC output as described above with the resistance R
If the transistor Q ₅ is turned on by detecting the increase in the voltage across both terminals of R ₇ and R _8, the transistor Q ₄ is turned on by this and a current flows through the resistor R ₄ via the transistor Q ₄ , so that the capacitor C ₅ is charged. The time constant at the time of the change is changed, and the transistor Q ₃ is turned on. Transistor Q
_{When 3} is turned on, the impedance in the feedback loop of the switching element Q ₂ is smaller than the resistance value of the resistor R ₂ , so that the on-time t ₂ 'of the switching element Q ₂ is as shown in FIG. 2 (b). ON time t in the normal state
_Shorter than ₂ . Here, charging from the charge amount per unit time of the capacitor C ₀ is determined by the switching element Q ₂ on-time t _2, the capacitor C ₀ by shortening the ON time of the switching element Q ₂ when an abnormality as described above The amount can be reduced, and the abnormal increase in the DC output of the chopper unit 1 can be suppressed.

According to the structure of the present embodiment, even if a light load is connected to the inverter device or the DC output of the chopper section 1 rises abnormally due to a short circuit between the output terminals or the like, such an abnormal DC output occurs. Since the rise is detected and the impedance variable portion 3 changes the impedance in the feedback loop to the switching element Q ₂ which is shared by the chopper portion 1 and the inverter portion 2, the switching element Q is changed by changing the impedance. ₂ on-time t ₂ is shorter than the normal state, thereby it is possible to suppress the increase of the DC output of the chopper unit 1 achieves protection circuit to suppress the output rise during abnormal at relatively simple circuit configuration be able to.

(Embodiment 2 ) FIG. 3 is a circuit diagram of a second embodiment of the present invention in which field effect transistors Q ₁ and Q are used as switching elements.
The configuration is almost the same as that of the first embodiment except that ₂ is used.
That is, the on-time t ₂ field effect transistor Q ₂ of the alternate side in the normal state, the other of the field effect transistor Q
_Although it is almost the same as the on time t _{1 of 1} , the impedance of the feedback loop connected to the gate of the field effect transistor Q ₂ changes when the transistor Q ₃ of the impedance variable unit ₃ is turned on at the time of abnormality, and the field effect Since the on-time t ₂ ′ of the transistor Q ₂ is shorter than the on-time t _{2 in the} normal state, the rise of the DC output of the chopper section 1 can be suppressed.

(Embodiment 3 ) FIG. 4 is a circuit diagram of a third embodiment of the present invention. The configuration other than the impedance variable section 4 is the same as that of the second embodiment.
Is common with. The impedance variable unit 4 in this embodiment includes resistors R ₉ , R ₁₀ and Zener diode ZD ₆ which are detecting units for detecting the DC output of the chopper unit 1, and a thyristor SCR _1, and is capable of increasing the DC output at the time of abnormality. the voltage across the resistor R ₁₀ is thyristor SCR ₁ and a trigger signal is applied to the gate of the thyristor SCR ₁ at the time beyond the Zener voltage of the Zener diode ZD ₆ is turned on. Thus, the switching element Q ₂ of the alternate side is stopped or intermittently operated, two on-off control of the switching elements Q _1, Q ₂ and unbalanced, shortening the on-time t ₂ the switching element Q ₂ As a result, it is possible to suppress an increase in the DC output of the chopper unit 1 at the time of abnormality.

( Fourth Embodiment) FIG. 5 shows a circuit diagram of a fourth embodiment of the present invention. Since the basic structure is common to that of the first embodiment, the common parts are the same. The reference numerals are attached and the description is omitted. In the present embodiment, the ballast choke CH ₁ and the balancer choke CH ₂ are connected in series to the primary winding n ₁ of the current transformer CT, and _two ballast chokes CH ₁ and balancer chokes CH ₂ are provided at the output end of the inverter unit 2 via the balancer choke CH ₂ . The discharge lamps La ₁ and La ₂ are connected in parallel. Further, the secondary sides of the ballast choke CH ₁ and the balancer choke CH ₂ are connected to the capacitor C ₄ via the diodes D ₄ and D ₅ .

In the impedance variable section 5, a resistor R ₁₃ and a capacitor C ₇ are provided between both ends of the capacitor C _4.
And a parallel circuit of the transistor Q ₇ are connected in series, and the base of the transistor Q ₆ is connected to the collector of the transistor Q ₇ via the Zener diode ZD ₇ . Moreover, the base of the transistor Q ₇ is Yes and the collector of the transistor Q ₈ is connected, a second current transformer CT to the base of the transistor Q ₈
The secondary winding n ₂ is connected in parallel to the series circuit of the diode D ₆ and the resistors R ₁₁ and R ₁₂ .

Next, the operation of this embodiment will be described.
First, when the two discharge lamps La ₁ and La ₂ are normally lit, the secondary output V of the ballast choke CH ₁ is
_1, between the secondary output V ₂ of the balancer choke CH _2, the magnitude relationship of V ₂ <V ₁ is satisfied. On the other hand, at this time, the transistor Q ₈ is on and the transistor Q ₇ is off, so that the voltage across the capacitor C ₇ becomes lower than the Zener voltage of the Zener diode ZD ₇ . Therefore, the transistor Q ₆ whose base is connected to the Zener diode ZD ₇ is off, and the on-time t ₂ of the switching element Q ₂ on the shared side is the on-time in the steady state.

Here, the two discharge lamps La ₁ and La ₂
When one of the two is removed, the secondary output V ₁ of the ballast choke CH ₁ becomes larger than the secondary output V ₂ of the balancer choke CH ₂ (V ₁ <V ₂ ). As a result, the voltage across the capacitor C ₇ of the impedance variable section 5 rises and exceeds the Zener voltage of the Zener diode ZD ₇ , so that the transistor Q ₆ is turned on and the switching element Q on the shared side is used.
Turn off ₂ . That is, when one of the discharge lamps La ₁ (or La ₂₎ as is disconnected, the switching element Q ₂ impedance varying unit 5 is to reduce the impedance of the feedback loop of the switching element Q ₂
The on-time t ₂ is shortened, so that the increase in the DC output of the chopper unit 1 is suppressed. At this time, the switching element Q ₂ is turned on / off at an on-time t ₂ that gives an output that allows the remaining discharge lamp La ₂ (or La ₁ ) to steadily light up. Further, when the switching element Q ₂ is turned off, the output of the secondary winding n ₂ of the current transformer CT is reduced, so that the transistor Q ₈ is turned off, which turns on the transistor Q _{7 and} charges the capacitor C _7. It is discharging.

On the other hand, even when the two discharge lamps La ₁ and La ₂ are disconnected or the output terminals of the inverter section 2 are short-circuited, the voltage across the capacitor C ₇ rises and the transistor Q ₆ turns on. and the on-time t ₂ of the switching element Q ₂ is shorter than the steady state, is the increase of the DC output of the chopper unit 1 can be suppressed. Also, the discharge lamp L
Ballast choke CH ₁ during preheating of filament a
A secondary output V ₁ of the balancer choke the secondary output V ₂ of CH _2, although both larger than the steady state, the transistor Q ₆ is turned on the voltage across the capacitor C ₇ Also in this case rises from which the on-time t ₂ the switching element Q ₂ shorter than the time constant reduces the current and voltage during preheat to prevent so-called Madokaten of the discharge lamp La _1, La _2.

In the configuration of this embodiment, two discharge lamps L
Abnormalities such as light load (for example, one of the discharge lamps La ₁ and La ₂ is disconnected) or short circuit due to the secondary side output of the ballast choke CH ₁ and the balancer choke CH ₂ connected to a ₁ and La _2. Is detected and the impedance connected to the switching element Q ₂ which is also used is changed by the impedance variable circuit 4, the on-time t ₂ of the switching element Q ₂ becomes shorter than that in the steady state in the case of the above abnormality, The increase in the DC output of the chopper unit 1 is suppressed, and damage to circuit elements and loads can be prevented.

As shown in FIG. 6 , a choke coil L ₃ and a capacitor C are provided on the secondary side of the balancer choke CH _2.
Connect a filter consisting of ₁₀ and balancer choke CH
_{If the} vibration component included in the secondary output of 2 is removed, the detection accuracy at the time of abnormality can be improved. Also, the figure
7 in the structure of FIG 6, the capacitors Ca, Cb,
Starting circuit 6 including resistors Ra, Rb, Diac Qd, etc.
The starting circuit 6 connects a series circuit of a diac Qd and resistors Ra and Rb between the gate of the field-effect transistor Q ₂ on the shared side and the drain of the other field-effect transistor Q _1. In addition, the capacitor Cb is connected in parallel with the series circuit of the field effect transistors Q ₁ and Q ₂ , and the capacitor Ca is connected in parallel with the diac Qd. And AC power supply AC
When the power is turned on, the capacitors Ca and Cb are charged and the voltage across them rises, so that the diac Qd conducts and the gate voltage is applied to the field-effect transistor Q ₂ on the shared side, and the chopper section 1 and the inverter section. 2 is activated.

When the discharge lamp La is used as a load by controlling the on / off times of the switching elements Q ₁ and Q ₂ of the inverter unit 2 to be unbalanced as in the above-described first to fourth embodiments. The present inventor has confirmed by experiments that the circuit operation can be stabilized at the time of starting. That is, although the clear reason has not been clarified, in the starting process of the discharge lamp La, that is, the process of transitioning from the preheating state to the lighting via the half-wave lighting, the operation in the half-wave lighting state (operation unstable state) Current transformer C
This is considered to be to complement the operation of T in an unbalanced state.

( Fifth Embodiment) FIG. 8 is a circuit diagram showing a fifth embodiment of the present invention. Since the basic structure is the same as that of the fourth embodiment, the common parts are the same. The explanation is omitted by attaching the reference numeral,
Only the characteristic parts of this embodiment will be described. When the discharge lamp La is connected as a load, in order to prolong the life of the filament of the discharge lamp La, it is general to perform a pre-heating in which a current is passed through the filament to preheat it before the discharge lamp La is started. . In this case,
As shown in FIG. 11 , a control circuit 10 for controlling on / off of _two switching elements Q ₁ and Q ₂ in an inverter unit 2 ′, a timer circuit and the like for performing preheating control for supplying a preheating current for a predetermined time is provided. The control circuit 10 increases the switching frequency of the switching elements Q ₁ and Q ₂ at the time of preheating to reduce the DC output of the chopper unit 1 to perform preheating. However, the provision of the control circuit 10 as described above is effective for preheating and starting.
The control during regular operation becomes complicated, leading to an increase in cost.

[0031] Therefore, in the present embodiment, connecting the emitter and collector of both ends transistor Qc of 'the inductor L ₁ with connecting' inductor L ₁ in series with the inductor L ₁ of the chopper unit 1, further, the transistor Q
It is characterized in that it has an inductance variable circuit 7 formed by connecting a timer circuit 7a to the base of c. The transistor Qc of the variable inductance circuit 7 is turned on in a steady state (the state where the discharge lamp La is lit) and is turned off by the timer circuit 7a for a predetermined preheating time during preheating. That is, in the steady state, the transistor Q
Since c is on, both ends of the inductor L ₁ ′ are bypassed by the transistor Qc.
It is only _one inductor L ₁ that contributes to the operation of. On the other hand, at the time of preheating inductor L ₁ to the inductor L ₁ to the transistor Qc is turned off are connected in series.
Therefore, during preheating, the DC output of the chopper unit 1 can be made lower than during steady state. Then, the timer circuit 7a
At a predetermined preheating time, the transistor Qc is turned on after the preheating time has elapsed, and the DC output of the chopper unit 1 required for a steady state is obtained.

In the configuration of this embodiment, the preheating current is supplied from the inverter section 2 during preheating, and the inductance variable circuit 7 changes the inductance value in the chopper section 1 between preheating and steady state. The DC output required during preheating and the DC output required during steady state can be obtained with a simple configuration, and the filament of the discharge lamp La can be preheated at low cost without providing a special control circuit for preheating. it can.

( Sixth Embodiment) FIG. 9 is a circuit diagram showing a sixth embodiment of the present invention. Since the basic structure is the same as that of the fifth embodiment, the common parts are the same. The explanation is omitted by attaching the reference numeral,
Only the characteristic parts of this embodiment will be described. In this embodiment, a thyristor SCR ₂ with connecting thyristor SCR ₂ to the inductor L ₁ and the series of chopper 1
It is characterized in that a timer circuit 8a is connected to the gate of and a diode D ₁₀ is connected in antiparallel between the cathode of the thyristor SCR ₂ and the drain of the field effect transistor Q ₁ . This timer circuit 8a turns off the thyristor SCR ₂ at the time of preheating to stop the operation of the chopper unit 1 so that the DC output of the chopper unit 1 at the time of preheating does not increase, and when the time limit of the preheating time ends, the gate circuit 8a A voltage is applied to turn on the thyristor SCR ₂ to operate the chopper unit 1,
The timer circuit 8a and the thyristor SCR ₂ constitute the chopper operation inhibiting means 8. When the operation of the chopper unit 1 is stopped, the preheating current is supplied to the discharge lamp La via the diode D ₁₀ .

In the structure of this embodiment, the chopper operation prohibiting means 8 controls the thyristor SCR ₂ to be turned on and off so that the chopper section 1 does not operate during preheating. The direct current output can be obtained with a simple configuration, and the filament of the discharge lamp La can be preheated at low cost without providing a special control circuit for preheating.

In the fifth and sixth embodiments, since the inductor L ₁ of the chopper section 1 acts on the inrush current when the AC power source AC is turned on, the inductor L ₁ acts to prevent the inrush current. There is also an advantage that the application of the inrush current to 2 can be suppressed low.

[0036]

According to the invention of claim 1, a chopper portion provided with a chopper switching element for connecting and disconnecting a DC power supply,
An inverter unit that has a plurality of inverter switching elements and alternately turns these inverter switching elements on and off to convert the output of the chopper section to alternating power and output the same, and each inverter by feeding back the alternating output of the inverter section. the use switching element and a feedback section for controlling on-off, the inverter device comprising also serves as a chopper switching element of the chopper unit and one inverter switching element of the inverter section, straight chopper unit
At least one from a detector that detects the current output and a feedback unit
Of the alternating output to the switching element of the inverter
Impedance that varies the impedance in the loop
The variable impedance section is provided by the detecting section.
If a rise in the DC output of the output chopper is detected, the feedback
Of the chopper by reducing the impedance of the loop
Inverter switch that is also used as an switching element
Since the ON time of the switching element has been shortened , a light load is connected.
The DC output of the chopper section due to a short circuit between the output terminals, etc.
If it constantly rises, such an abnormal rise in DC output
Detected by the detection unit, and changed by the impedance variable unit.
Inverter switch that doubles as a switching element for the inverter
The on-time of the switching element should be shorter than in the normal state.
The increase in the DC output of the chopper can be suppressed by and
In comparison, the circuit configuration is simple and the output rise is suppressed in the event of an abnormality.
There is an effect that the road can be protected .

The invention of claim 2 has a filament
Use the discharge lamp as a load and put the filament first before starting the discharge lamp.
Supply preheating current from the inverter for preheating.
Since made, pre without have a circuit configuration for specially preheating
Heat current can be supplied to the filament , circuit configuration
There is an effect that can be simplified .

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment.

2A and 2B are waveform charts for explaining the operation of the same.

FIG. 3 is a circuit diagram showing a second embodiment.

FIG. 4 is a circuit diagram showing a third embodiment.

FIG. 5 is a circuit diagram showing a fourth embodiment.

FIG. 6 is a circuit diagram showing another configuration of the above .

FIG. 7 is a circuit diagram showing still another configuration of the above .

FIG. 8 is a circuit diagram showing a fifth embodiment.

FIG. 9 is a circuit diagram showing a sixth embodiment .

FIG. 10 is a circuit diagram showing a conventional example .

FIG. 11 is a circuit diagram showing another conventional example .

[Explanation of symbols]

First chopper unit 2 inverter Q _1, Q ₂ switching elements CT current transformer n _1, n ₂ 2 winding La discharge lamp

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuyuki Kiyozumi 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Yoshimitsu Hiratsune, 1048, Kadoma, Kadoma City, Osaka Matsushita Electric Works, Ltd. ( 56) References JP-A-3-198670 (JP, A) JP-A-3-276599 (JP, A) JP-A-6-267686 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02M 7/5383 H02M 7/538

Claims (2)

(57) [Claims] 1. A chopper section provided with a chopper switching element for connecting and disconnecting a DC power source, and a plurality of inverter switching elements provided to alternately turn on and off the inverter switching elements to output alternating power to the chopper section. And a feedback unit that feeds back an alternating output of the inverter unit to control ON / OFF of each switching element for the inverter, and the switching element for the chopper of the chopper section is provided as one of the inverter sections. In an inverter device that also serves as an inverter switching element , a detector that detects the DC output of the chopper
At least one inverter switch from the output section and the feedback section.
Impedance in the feedback loop of the alternating output to the
It has an impedance variable part that changes the impedance.
The impedance variable part uses the direct current of the chopper part by the detection part.
Impedance of feedback loop when output rise is detected
It also serves as a chopper switching element by reducing
ON time of the switching element for the inverter used
Inverter device characterized by shortening . 2. A discharge lamp having a filament as a load
To preheat the filament before starting the discharge lamp
2. The inverter device according to claim 1 , wherein the preheating current is supplied from the inverter section .