JP3620160B2 - Inverter device, discharge lamp lighting device and lighting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inverter device, a discharge lamp lighting device, and a lighting device.
[0002]
[Prior art]
FIG. 7 is a circuit diagram showing a conventional current feedback self-oscillation type inverter device.
[0003]
In the figure, 71 is an AC power source, 72 is a DC power source, 73 is a switching means, 74 is an insulating output transformer, 75 is a load such as a discharge lamp, and 76 is a current feedback circuit.
[0004]
The direct current power source 72 is composed of a rectifier circuit and outputs the rectified direct current of the alternating current power source 71.
[0005]
The switching means 73 is connected to apply the switched voltage to the primary winding of the output transformer 74.
[0006]
The current feedback circuit 76 is a current in which the primary winding is inserted in series in the circuit of the load 75 connected between the secondary windings of the output transformer 74 and the secondary winding is connected to the control terminal of the switching means. It includes a transformer 76a and is configured to provide positive feedback to the switching means 73.
[0007]
[Problems to be solved by the invention]
In the prior art shown in FIG. 7, when there is a non-negligible stray capacitance between the wiring paths leading to the load 75, a weak feedback current is generated in the state where the load is removed, thereby causing oscillation. May continue. Since the oscillation at this time has a small feedback current, the drive is insufficient with respect to the switching means 73 of the inverter device, resulting in abnormal oscillation. That is, since there are few drives at the time of abnormal oscillation, the voltage drop of the switching means is large, therefore the switching loss increases, the temperature rise of the switching means becomes excessive, and sometimes the switching means is destroyed.
[0008]
Also, depending on the value of the floating capacitance, the inverter device operates near the resonance point between the floating capacitance and the secondary inductance of the output transformer, so that the secondary open-circuit voltage becomes extremely high, and the lamp is replaced. In some cases, there is a problem that an electric shock is given to the human body or the life of the output transformer is shortened.
[0009]
Further, there is a problem that the switching characteristics from the start to the stable operation when the lamp is removed are not good.
[0010]
The present invention provides an inverter device having a current feedback circuit in which a feedback loop is substantially disconnected when a load is removed, and even if there is a non-negligible stray capacitance between wiring lines leading to the load. An object of the present invention is to provide an inverter device, a discharge lamp lighting device, and an illumination device that reliably stop the inverter operation when removed.
[0011]
[Means for achieving the object]
The inverter device according to the first aspect of the present invention comprises switching means arranged to switch direct current to supply alternating current to a load; and performs positive feedback to cause the switching means to self-oscillate, but connected via a wiring path Current feedback circuit in which the feedback loop is substantially disconnected when the load being removed is removed; current of the opposite polarity may be supplied to the current feedback circuit when the load is removed, and may be caused by stray capacitance between the wires And reverse polarity feedback means capable of canceling the feedback current .
[0012]
In the present invention and each of the following inventions, the definitions and technical meanings of terms are as follows unless otherwise specified.
[0013]
Any load may be used, but a discharge lamp, particularly a fluorescent lamp, is suitable as the load.
[0014]
The switching means allows all kinds of switching means used in the inverter device, such as a field effect transistor that can use a built-in parasitic diode for reverse current flow. In the case where the safety means is made to respond to the change of the above, a bipolar transistor is particularly suitable as the switching means. In the case of using a bipolar transistor, a diode can be reversely connected between the collector and emitter of the transistor in order to pass a reverse current.
[0015]
In constructing the inverter main circuit using the switching means, all inverter circuits normally used are allowed. That is, a half-bridge circuit, a one-stone circuit, a parallel circuit, or the like can be used. Further, as a modification of the half-bridge type circuit, a circuit described in Japanese Patent Application Laid-Open No. 8-98555 related to the application of the same applicant can also be used. According to this circuit configuration, the input voltage can be smoothed to reduce the pulsation of the output voltage, and the input power factor can be increased to reduce the harmonics of the input current.
[0016]
The control circuit may have any circuit configuration as long as the switching means is turned on and off. The on / off frequency is higher than the frequency of the AC power supply, and is several KHz or more, preferably 20 KHz or more.
[0017]
If the reverse polarity feedback means supplies the current feedback circuit with a reverse polarity current that cancels the current that can flow to the current feedback circuit due to the stray capacitance between the wiring paths when the load is removed, the circuit configuration is as follows. Any thing is acceptable. It should be noted that canceling does not mean only complete canceling, but if the switching means does not perform undesired switching, it may be allowed that some feedback due to floating capacitance remains. Even if the reverse polarity feedback amount by the reverse polarity feedback means is larger than the feedback amount by the floating capacitance, the switching means does not perform undesired switching.
[0018]
If the wiring path is allowed up to a maximum of 10 m in design, in the case of a vinyl electric wire, the stray capacitance between the wiring paths is about 300 pF. When the load is a fluorescent lamp intended for illumination, the stray capacitance between the normal wiring paths is about several pF to several hundred pF.
However, the present invention is not subject to any restrictions on the wiring path length and the type of electric wire, and a desired electric wire can be used by arbitrarily setting a desired wiring length. Therefore, the stray capacitance between the wiring paths also varies depending on the wiring path length and the type of electric wire.
[0019]
Thus, in the present invention, when the load is removed, even if there is a stray capacitance that cannot be ignored between the wiring paths, a reverse polarity current by the reverse polarity feedback means is supplied to the current feedback circuit. As a result, the feedback current due to the floating capacitance is canceled out, so that an undesired feedback current does not flow through the current transformer. That is, since current feedback is not performed, the inverter device reliably stops the inverter operation.
[0020]
An inverter device according to a second aspect of the present invention is an insulated output transformer capable of connecting a load to a secondary side via a wiring path; and applying a switched voltage to a primary winding of the output transformer. The switching means arranged; the primary winding is inserted into the secondary circuit of the output transformer, and the secondary winding is connected to the control terminal of the switching means so that the switching means performs a self-excited oscillation operation of the current feedback type A current feedback circuit including a selected current transformer; and a reverse current that can be supplied to the current feedback circuit when the load is removed to cancel the feedback current that may be caused by stray capacitance between the wiring paths And a polarity feedback means.
[0021]
The output transformer may be provided with a leakage inductance so that a current limiting action is performed when the load is a discharge lamp, or the current limiting impedance is externally provided before or after the output transformer without actively providing a leakage impedance. You may make it attach.
[0022]
According to a third aspect of the present invention, there is provided an inverter device according to the second aspect, wherein the reverse polarity feedback means includes a series circuit of a tertiary winding and a capacitor having a reverse polarity with respect to the secondary winding of the output transformer. The transformer is configured to be connected in parallel to the primary winding of the transformer.
[0023]
By configuring as described above, the present invention supplies a reverse polarity feedback current using a low voltage generated by the tertiary winding of the output transformer as a power source to the primary winding of the current transformer. Thus, feedback current cancellation is performed on the primary side of the current transformer.
[0024]
The tertiary winding may be further used for filament heating. In this case, both ends of the capacitor may be connected to both ends of the filament to be heated. The filament heating may be performed by providing a separate quaternary winding if necessary.
[0025]
According to a fourth aspect of the present invention, there is provided the inverter device according to the first or second aspect, wherein the reverse polarity feedback means is constituted by an inductor connected between the output terminals.
[0026]
A current with a lagging phase flows through the inductor. On the other hand, since the current flowing through the floating capacitance is in a leading phase, both currents are canceled out. For this reason, if the value of the inductor is appropriately selected, the positive feedback to the switching means can be substantially eliminated.
[0027]
An inverter device according to a fifth aspect of the present invention comprises switching means arranged to switch direct current and supply alternating current to a load; and performs positive feedback to cause the switching means to self-oscillate, but connected via a wiring path A current feedback circuit in which the feedback loop is substantially disconnected when the load to be removed is removed; frequency response that acts to allow current feedback only at the frequency at which the load is mounted in relation to the frequency change when the load is removed And means.
[0028]
In the self-excited oscillation type inverter device, when the load is removed, the response frequency of the circuit changes, so the oscillation frequency is affected and changes. In particular, in the case of a circuit type in which the load is a fluorescent lamp and a preheating capacitor is connected between the non-power supply terminals of each filament electrode, the preheating capacitor opens when the fluorescent lamp is removed. Changes.
[0029]
The frequency responsive means acts so that current feedback is performed only when a load is mounted in response to this frequency change. For example, results in a frequency when the load is removed, or to short-circuit the current feedback circuitry, if the circuit to open, current feedback is not performed. Further, the circuit may be configured to pass current feedback only with respect to the frequency when the load is mounted. In this way, current feedback is blocked at the frequency when the load is removed.
[0030]
Thus, according to the present invention, current feedback is allowed only when the load is mounted in response to a frequency change associated with the loading / unloading of the load, so that the inverter device does not oscillate when the load is removed.
[0031]
An inverter device according to a sixth aspect of the present invention is an insulated output transformer capable of connecting a load to a secondary side via a wiring path; and applying a switched voltage to a primary winding of the output transformer. The switching means arranged; the primary winding is inserted into the secondary circuit of the output transformer, and the secondary winding is connected to the control terminal of the switching means so that the switching means performs a self-excited oscillation operation of the current feedback type A current feedback circuit including a current transformer, and frequency responsive means acting so that current feedback can be performed only at the frequency when the load is mounted in relation to the frequency change when the load is removed. It is characterized by.
[0032]
The output transformer is as described for claim 2 and the frequency response means is as described for claim 5.
[0033]
According to a seventh aspect of the present invention, there is provided the inverter device according to the fifth or sixth aspect, wherein the frequency response means comprises a trap means having a trap frequency corresponding to a frequency when the load is removed, and is configured by a trap means inserted in the current feedback circuit. It is characterized by being.
[0034]
In the present invention, the frequency response means is configured by using the trap means, but when the series resonance type is used, since the impedance becomes zero at the trap frequency, the current feedback circuit is connected to be short-circuited. do it. Further, when using a parallel resonance type, the impedance becomes infinite at the trap frequency, and therefore the current feedback circuit may be connected so as to be opened.
[0035]
Thus, current feedback is substantially eliminated by performing a trap action in response to the oscillation frequency when the load is removed and disabling the current feedback circuit.
[0036]
An inverter device according to an eighth aspect of the present invention is the inverter device according to the fifth or sixth aspect, wherein the frequency responsive means has a characteristic of selectively passing a frequency when a load is mounted, and is a filter means inserted into a current feedback circuit. It is characterized by comprising.
[0037]
In the present invention, the frequency response means is configured by using the filter means, and since only the oscillation frequency at the time of loading is passed, the filter means prevents the current feedback when the load is removed. There is virtually no current feedback.
[0038]
A discharge lamp lighting device according to a ninth aspect of the invention includes the inverter device according to any one of the first to eighth aspects; and a discharge lamp energized by an output of the inverter device. .
[0039]
The present invention is a discharge lamp lighting device having the functions and features of claims 1 to 8.
[0040]
An illumination device according to a tenth aspect of the invention is characterized by comprising: an illumination device main body; and a discharge lamp lighting device according to the ninth aspect disposed in the illumination device main body.
[0041]
The present invention has the operations and characteristics of claims 1 to 8 in a lighting device such as a lighting fixture.
[0042]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0043]
FIG. 1 is a circuit diagram showing a first embodiment of an inverter device and a discharge lamp lighting device according to the present invention.
[0044]
In the figure, 1 is an AC power source, 2 is a DC power source, 3 is a switching means, 4 is an output transformer, 5 is a load such as a discharge lamp, 6 is a current feedback circuit, and 7 is a reverse polarity feedback means.
[0045]
The DC power supply 2 is of a type obtained by rectifying AC.
[0046]
The switching means 3 is composed of, for example, a bipolar type transistor, and is connected in series with the primary winding 4a of the output transformer between the DC power sources, and applies a switched voltage to the primary winding 4a.
[0047]
The output transformer 4 includes a secondary winding 4b and a tertiary winding 4c having a polarity opposite to that of the secondary winding 4b. The secondary winding 4b is provided with a leakage impedance, and is configured to perform a current-limiting action when a discharge lamp such as a fluorescent lamp is connected as the load 5 between the secondary windings 4b. Capacitor C ₁ for resonance is connected in parallel with the primary winding 4a.
[0048]
Fluorescent lamp load 5 is connected a capacitor C ₂ of the filament preheating between non-power terminal.
[0049]
The current feedback circuit 6 includes a current transformer 6 a in which a primary winding 6 a 1 is connected in series with a load 5. The base of the switching means 3 to the secondary winding 6a2 of the current transformer 6a via a capacitor C _3, constitute a current feedback circuit 6 connected between the emitter.
[0050]
Reverse polarity feedback means 7 includes a series circuit of the tertiary winding 4c and the capacitor C ₄ of the output transformer 4 is connected in parallel with the primary winding 6a1 of the current transformer 6a. The tertiary winding 4c has a reverse polarity with respect to the secondary winding 4b.
[0051]
8 is a so-called reset circuit consists of a series circuit of a diode 8a and resistor 8b, the switching means 3 based, and are connected between the emitter, a function of discharging the electric charge of the capacitor C ₃ to the OFF state of the switching means 3 Have.
[0052]
_CS is a floating electrostatic capacitance between wiring paths.
[0053]
If the load 5 is removed while the inverter device is oscillating, a weak feedback current flows in the secondary winding 6a2 of the current transformer 6a due to the stray capacitance compared to when the load is attached, but at the same time, Since the polarity feedback means 7 passes a current of reverse polarity to the current feedback circuit 6 in a direction to cancel the feedback current, the feedback current is canceled out and the feedback current to the switching means 3 does not substantially flow. . As described above, since the current feedback is substantially eliminated, the inverter operation of the inverter main circuit 3 is stopped. Therefore, no abnormal oscillation occurs. Incidentally, when the time of the load attached to the capacitor C ₂ for preheating is 0.01μF example, a voltage of several V is induced in the secondary winding 6a2 of the current transformer 6a, a reverse polarity feedback means according to the invention In the case where there is no current and the current due to the floating capacitance C _S is fed back, a voltage lower than the above is induced, causing abnormal switching.
[0054]
Next, specific numerical examples will be described.
[0055]
When the voltage _{V L} of the secondary winding 4b of the output transformer 4 100 V, 3 winding 4c voltage _{V 4} of 3V, the stray capacitance _{C S} and 300 pF, the capacitor _{C 4} can be obtained by the following formula .
[0056]
C ₄ = V _L · C _S / V ₄ = 10 × 10 ⁻⁹ = 10 nF
FIG. 2 is a circuit diagram showing a second embodiment of the inverter device and the discharge lamp lighting device of the present invention.
[0057]
The same parts as those in FIG.
[0058]
This embodiment differs from the first embodiment in reverse polarity feedback means. That is, an inductor L ₁ connected between the output terminal of the inverter device.
[0059]
Thus, the current fed back by the floating capacitance C _S is a leading current, whereas the current flowing through the inductor L ₁ is a lagging current , and therefore a current having a polarity opposite to the leading current. Are canceled out and substantially no current feedback is performed in the current feedback circuit.
[0060]
Next, specific numerical examples will be described.
[0061]
Since it suffices equal to the impedance of the impedance and the inductor of the stray capacitance, by the following equation to determine the value of the inductor L _1. Incidentally, the stray capacitance _{C S} is set to 300 pF.
[0062]
1 / 2πfC _S = 2πfL ₁
L ₁ = 4π ² f ² C _S = 33.8 mH
FIG. 3 is a circuit diagram showing a third embodiment of the inverter device and the discharge lamp lighting device of the present invention.
[0063]
The same parts as those in FIG.
[0064]
The present embodiment is characterized in that the frequency response means 9 is provided. The frequency responsive means 9 acts so that current feedback can be performed only at the frequency when the load is mounted in relation to the frequency change when the load 5 is removed. Trapping means is used in which the trap frequency is set to the frequency when the load is removed. That is, the trap means and therefore the frequency response means are formed of a series circuit of the inductor L ₂ and the capacitor C ₅ and are connected in parallel with the primary winding 6a1 of the current transformer 6a.
[0065]
Then, when the load 5 is removed, the frequency changes to the trap frequency, so that the impedance of the trap means becomes substantially zero, so that the feedback current is trapped and is not passed through the current transformer 6a. Like that. Accordingly, since current feedback is not performed, the inverter device stops the inverter operation.
[0066]
A specific numerical example will be described.
[0067]
If the frequency when the load 5 is attached is 50 KHz, and the frequency when the load 5 is removed is 200 KHz, the inductor L ₂ may be 2.9 μH and the capacitor C ₅ may be 0.22 μF.
[0068]
FIG. 4 is a circuit diagram showing a fourth embodiment of the inverter device and the discharge lamp lighting device according to the present invention.
[0069]
The same parts as those in FIG.
[0070]
This embodiment differs from the embodiment of FIG. 3 in the configuration of the frequency response means 9 ′. That is, the trap means including a parallel circuit of an inductor L ₃ and capacitor C ₆ of the current feedback circuit is inserted in series.
[0071]
Then, when the load 5 is removed, a frequency change occurs and becomes a trap frequency. Since the impedance of the trap means becomes very large due to the parallel resonance, the trap means acts as a trap to prevent current feedback. For this reason, the inverter device stops.
[0072]
A specific numerical example will be described.
[0073]
If the frequency when the load is mounted and the frequency when the load is removed are the same as in FIG. 3, the trap frequency is the same as in FIG. 3, and therefore the circuit constants can be the same.
[0074]
FIG. 5 is a circuit diagram showing a fifth embodiment of the inverter device and the discharge lamp lighting device according to the present invention.
[0075]
The same parts as those in FIG.
[0076]
This embodiment, "differs from the embodiment of FIG. 4 in that it uses a filter means. That is, the frequency response means 9" frequency response means 9, the filter means comprising a series circuit of an inductor L ₄ and the capacitor C ₇ In this case, the current feedback circuit 6 is inserted in series. The filter means uses the frequency when the load is mounted as the passing frequency.
[0077]
Thus, when the load 5 is mounted, the frequency response means 9 ″ passes the current feedback, so that the inverter device performs current feedback self-oscillation at the intended frequency, but when the load 5 is removed. Since the frequency changes, the frequency responsive means 9 ″ performs the blocking operation, so that the current feedback circuit is in an open circuit state and cannot perform the current feedback operation. For this reason, the inverter device stops.
[0078]
A specific numerical example will be described.
[0079]
If the frequency at the frequency and load removal at the load attachment the same as those of FIG. 3, for example L ₄ 10.1μH, may be a C ₇ to 1 .mu.F.
[0080]
FIG. 6 is a perspective view of a lighting fixture showing an embodiment of the lighting device of the present invention.
[0081]
In the figure, 10 is a lighting fixture body, and 11 is a fluorescent lamp.
[0082]
The luminaire main body 10 supports the fluorescent lamp 11 and incorporates the inverter device (not shown) of the present invention.
[0083]
【The invention's effect】
According to the invention of claims 1 to 8, in the inverter apparatus including a current feedback circuitry the feedback loop is substantially disconnected when removing the load, the floating electrostatic which can not be ignored between the wiring path to the load It is possible to provide an inverter device that reliably stops the inverter operation when the load is removed even if the capacity exists. Therefore, problems such as abnormal heat generation and destruction of the switching means can be prevented due to undesired abnormal switching.
[0084]
According to each of the first to fourth aspects of the present invention, the feedback current due to the stray capacitance is canceled by the reverse polarity current by the reverse polarity feedback means, so that the feedback is substantially eliminated when the load is removed. The operation can be stopped reliably.
[0085]
According to each of the fifth to eighth aspects of the invention, in addition, the frequency response device maintains the current feedback at the frequency when the load is mounted, and prevents the current feedback at the frequency when the load is removed, thereby ensuring the inverter operation. It is possible to provide an inverter device that stops.
[0086]
According to invention of Claim 9, the discharge lamp lighting device which has the effect of Claims 1 thru | or 8 can be provided.
[0087]
According to invention of Claim 10, the illuminating device which has the effect of Claims 1 thru | or 8 can be provided.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a first embodiment of an inverter device and a discharge lamp lighting device according to the present invention. FIG. 2 is a circuit diagram showing a second embodiment of the inverter device and the discharge lamp lighting device according to the present invention. 3 is a circuit diagram showing a third embodiment of the inverter device and the discharge lamp lighting device according to the present invention. FIG. 4 is a circuit diagram showing the fourth embodiment of the inverter device and the discharge lamp lighting device according to the present invention. 6 is a circuit diagram showing a fifth embodiment of an inverter device and a discharge lamp lighting device according to the present invention. FIG. 6 is a perspective view of a lighting fixture showing an embodiment of the lighting device according to the present invention. Circuit diagram showing an excitation oscillation type inverter device [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... AC power supply 2 ... DC power supply 3 ... Switching means 4 ... Output transformer 5 ... Load 6 ... Current feedback circuit 7 ... Reverse polarity feedback means _CS ... Floating capacitance

Claims (10)

Switching means arranged to switch DC and supply AC to the load;
A current feedback circuit that performs positive feedback to cause self-excited oscillation of the switching means, but when the load connected via the wiring path is removed, the feedback loop is substantially disconnected;
Reverse polarity feedback means capable of supplying a reverse polarity current to the current feedback circuit when the load is removed to cancel the feedback current that may be caused by the stray capacitance between the wiring paths;
An inverter device comprising: An insulated output transformer that can connect a load to the secondary side via a wiring path;
Switching means arranged to apply a switched voltage to the primary winding of the output transformer;
A current including a current transformer connected to the control terminal of the switching means so that the primary winding is inserted into the secondary side circuit of the output transformer, and the secondary winding performs the self-excited oscillation operation of the current feedback type. A feedback circuit;
Reverse polarity feedback means capable of supplying a reverse polarity current to the current feedback circuit when the load is removed to cancel the feedback current that may be caused by the stray capacitance between the wiring paths;
An inverter device comprising: The reverse polarity feedback means includes a series circuit of a reverse polarity tertiary winding and a capacitor with respect to the secondary winding of the output transformer and is connected in parallel to the primary winding of the current transformer. The inverter device according to claim 2, wherein: 3. The inverter apparatus according to claim 1, wherein the reverse polarity feedback means is constituted by an inductor connected between the output terminals. Switching means arranged to switch DC and supply AC to the load;
A current feedback circuit that performs positive feedback to cause self-excited oscillation of the switching means, but when the load connected via the wiring path is removed, the feedback loop is substantially disconnected;
Frequency responsive means acting to allow current feedback only at the frequency when the load is mounted in relation to the frequency change when the load is removed;
An inverter device comprising: An insulated output transformer that can connect a load to the secondary side via a wiring path;
Switching means arranged to apply a switched voltage to the primary winding of the output transformer;
A current including a current transformer connected to the control terminal of the switching means so that the primary winding is inserted into the secondary side circuit of the output transformer, and the secondary winding performs the self-excited oscillation operation of the current feedback type. A feedback circuit;
Frequency responsive means acting to allow current feedback only at the frequency when the load is mounted in relation to the frequency change when the load is removed;
An inverter device comprising: 7. The inverter device according to claim 5, wherein the frequency responsive means has a trap frequency corresponding to a frequency when the load is removed, and is constituted by trap means inserted in a current feedback circuit. 7. The inverter device according to claim 5, wherein the frequency responsive means has a characteristic of selectively allowing the frequency when the load is mounted to pass therethrough, and is configured by filter means inserted in the current feedback circuit. An inverter device according to any one of claims 1 to 8;
A discharge lamp energized by the output of the inverter device;
A discharge lamp lighting device comprising: A lighting device body;
A discharge lamp lighting device according to claim 9 disposed in the illuminating device body;
An illumination device comprising:

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