JP2005071619A - Discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device provided with a neutral point type stepdown noninverting inverter, having a simple circuit configuration and few higher harmonic wave. <P>SOLUTION: This discharge lamp lighting device is provided with a bridge rectifying/converting circuit BRC formed by parallel connection of a series circuit of a pair of switching elements Q1, Q2 switching by high frequency by turns and a series circuit of a pair of rectifying devices D1, D2, and connected with a low-frequency AC power supply AC between AC input ends between a junction j1 of the switching elements Q1, Q2 and a junction j2 of the rectifying devices D1, D2, a chopper circuit BUC containing at least one of a counter-electromotive force feedback circuit FBC with inductors L1, L1 inserted in a position on a circuit through which the low-frequency AC current and high frequency current flow bidirectionally and switching elements Q1, Q2, a resonant circuit RC resonating with high-frequency voltage, and a discharge lamp DL to which the resonance voltage is applied. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a discharge lamp lighting device including a pair of switching elements connected in series.
[0002]
[Prior art]
For example, a countermeasure against harmonics in an electronic ballast for lighting that uses a low-frequency AC power source such as a commercial AC power source to light a discharge lamp at a high frequency is classified into a passive filter method, an active filter method, and a partial smoothing method. The active filter method includes a chopper method, a charge pump method, and a charge pump + chopper method.
[0003]
[Problems to be solved by the invention]
However, in a passive filter, a series inductor and a parallel capacitor are connected to a load and circuit constants are selected so that their resonance frequency resonates three times the power supply frequency. In particular, the inductor has a large power capacity. Since something is required, it is impossible to reduce the size and weight.
[0004]
In the active filter, in the case of the chopper type, an independent step-up chopper circuit is provided separately from the inverter, so that the number of parts increases and the cost increases. The charge pump method and the charge pump + chopper method are so-called composite types in which the switching element of the inverter is also used as the switching element of the active filter, but the circuit configuration is complicated and sufficient smoothing action cannot be obtained. There are problems such as.
[0005]
The partial smoothing circuit cannot satisfy the recent strict input current harmonic standards.
[0006]
An object of the present invention is to provide a discharge lamp lighting device having a neutral point step-down non-inverting inverter that switches a positive and negative polarity low-frequency AC power supply voltage at a high frequency, having a simple circuit configuration and less harmonics. And
[0007]
[Means for achieving the object]
The discharge lamp lighting device of the invention of claim 1 is formed by connecting in parallel a series circuit of a pair of switching elements and a series circuit of a pair of rectifying elements that are alternately switched at a high frequency, and connecting the pair of switching elements. A bridge-type rectification / conversion circuit in which a low-frequency AC power source is connected between an AC input terminal formed between a point and a connection point of a pair of rectifying elements; a low-frequency AC current and a high-frequency current of the bridge-type rectification / conversion circuit; And a chopper circuit including at least one of a pair of switching elements, an inductor inserted at a position on a circuit that both flow in both directions, a feedback circuit that feeds back electromotive force generated in the inductor, and a resonant circuit that resonates with a high-frequency voltage And a discharge lamp which is turned on when a resonance voltage of the resonance circuit is applied.
[0008]
In the present invention and each of the following inventions, the definitions and technical meanings of terms are as follows unless otherwise specified.
[0009]
In the present invention, “high frequency” means a frequency of 1 kHz or more, preferably 20 kHz or more exceeding the limit of the audible frequency, more preferably 40 kHz or more higher than the carrier frequency of the remote control.
[0010]
<Bridge Type Rectification / Conversion Circuit> The bridge type rectification / conversion circuit is a means for rectifying low-frequency alternating current to convert it into direct current, and for converting direct current into high frequency by switching. Therefore, a neutral point step-down inverter Works as. In order to convert low-frequency alternating current into direct current, a pair of rectifying elements mainly acts. A pair of switching elements acts to convert direct current to high frequency.
[0011]
The pair of switching elements may be either directly connected in series or indirectly connected in series via another circuit element such as a resistor. In addition, the pair of switching elements and the pair of rectifying elements only need to be able to function as a pair in terms of function, and both or either of the pair is allowed to be configured by a plurality of elements. Furthermore, the switching element may have any configuration as long as it is a controllable switching element that can be switched at a high frequency. For example, a bipolar transistor, an FET, or the like can be used.
[0012]
The low-frequency AC power supply may be connected alone between the AC input terminals of the bridge type rectification / conversion circuit, or may be connected in series with other circuit components such as an inductor of a chopper circuit.
[0013]
<About the Chopper Circuit> In the present invention, the “chopper circuit” refers to feedback of a counter electromotive force generated between both ends of an inductor by switching of a DC current, and converts a DC voltage of a certain voltage into another DC voltage having a different voltage. Means to do. Any type of chopper circuit such as a step-down type, a step-up type, or a reverse polarity type may be used. The inductor may be dedicated to the chopper or may also serve as an output transformer. The feedback circuit for returning the counter electromotive force may have any configuration. The switching of the direct current is performed by one or both of the pair of switching elements in the bridge type rectification / conversion circuit.
[0014]
<Regarding Resonant Circuit> The resonant circuit resonates with a high-frequency voltage formed by alternating switching of a pair of switching elements. It is formed by an inductor and a capacitor. The “inductor” means a circuit means having inductance, and is not limited to a choke coil. Therefore, a transformer or the like may be used as long as it has an appropriate inductance when viewed from the primary side. Thus, the resonance circuit forms a high voltage by resonance at the start of the discharge lamp, and promotes the start by applying this to the discharge lamp, and shapes the waveform of the high-frequency voltage into a sine wave.
[0015]
<Discharge Lamp> The discharge lamp may be any type, and for example, a low pressure discharge lamp such as a fluorescent lamp or a high pressure discharge lamp such as a metal halide lamp can be used. Further, the discharge lamp is connected to a position on the circuit where a resonant output of a high frequency voltage is applied. For example, a half-bridge inverter circuit that shares a pair of switching elements of a bridge-type rectification / conversion circuit and includes a resonance circuit in parallel with the bridge-type rectification / conversion circuit is configured to form an inductor for the resonance circuit. The discharge lamps can be connected in parallel or in series. In addition, a resonance circuit having one of the resonance elements as an inductor of a chopper circuit can be formed by sharing a part of the bridge type rectification / conversion circuit, and a discharge lamp can be connected in parallel or in series with the inductor. . In the above connection mode, in order to select and extract only the high-frequency component, a secondary winding is wound around the inductor to form an output transformer, and the discharge lamp is energized via the output transformer. Is desirable.
[0016]
<Other Configurations> Although not an essential component of the present invention, if the resonant voltage of the load circuit is insufficient for starting the discharge lamp, a separate igniter is generated from the high voltage. It can be connected to a load circuit so that a voltage pulse is applied to the discharge lamp.
[0017]
<Regarding the Action of the Present Invention> As a result of the present invention having the above-described configuration, a low-frequency AC voltage is full-wave rectified and switched at a high frequency in a bridge-type rectification / conversion circuit. Operation is performed.
[0018]
In addition, a low-frequency AC current that has been increased in frequency by switching flowing from the low-frequency AC power source and a high-frequency current generated by the chopper circuit flow bidirectionally in the inductor. Since the inductor only needs to have an impedance effective only for a high-frequency current due to switching of the switching element, the low-frequency AC power supply can operate without being substantially short-circuited. Therefore, the inductor of the chopper circuit can be reduced in size and weight.
[0019]
Further, the back electromotive force generated in the inductor of the chopper circuit is fed back by the alternate switching of the switching elements, and the fed back DC energy is converted into a high frequency by the switching of the switching elements. Therefore, a resonant circuit is connected to the circuit portion through which the high-frequency current that is switched by the low-frequency alternating current flowing from the low-frequency alternating current power source and the high-frequency current that is switched by the switched back DC energy flows, or feedback The discharge lamp can be turned on at a high frequency by connecting a resonance circuit to a circuit portion through which a high-frequency current with switched direct current energy flows, or by connecting the discharge lamp to be energized by the resonance output. it can.
[0020]
Furthermore, since the back electromotive force generated in the inductor of the chopper circuit is fed back by alternating switching of the switching elements and further converted to high frequency by switching of the switching elements, it is possible to obtain high conversion efficiency as a whole discharge lamp lighting device apparatus. it can. In addition, since the inverter operation and the chopper operation for generating a high frequency are performed using a common switching element, the mounting area of the wiring board is reduced, which is effective for miniaturization and cost reduction.
[0021]
The discharge lamp lighting device of the invention of claim 2 is formed by connecting in parallel a series circuit of a pair of switching elements and a series circuit of a pair of rectifying elements that are alternately switched at a high frequency, and connecting the pair of switching elements. A bridge type rectification / conversion circuit in which a low frequency AC power source is connected between an AC input end formed between a point and a connection point of a pair of rectifying elements; and a low frequency between the AC input ends of the bridge type rectification / conversion circuit An inductor connected in series with an AC power source, a feedback circuit that feeds back an electromotive force generated in the inductor, and a chopper circuit including at least one of a pair of switching elements as a constituent element; a resonant circuit that resonates with a high-frequency voltage; And a discharge lamp that is lit when a resonance voltage is applied thereto.
[0022]
The present invention defines a preferred configuration as a chopper circuit in the invention of claim 1. That is, the chopper circuit has an inductor connected in series with a low-frequency AC power supply between the AC input terminals of the bridge type rectification / conversion circuit. As the feedback circuit that feeds back the back electromotive force generated in the inductor, an appropriate circuit configuration can be adopted. For example, the feedback circuit can be configured using a full-wave rectifier circuit including four rectifier elements and a full-wave rectifier circuit including two rectifier elements and two other capacitors.
[0023]
And in this invention, in addition to the effect | action and effect in invention of Claim 1, there exist the following effect | actions and effects. That is, since the inductor is connected to the above position, it is possible to develop various connection positions and circuit configurations of the feedback circuit, the smoothing capacitor, and the discharge lamp as a load, and therefore, as a discharge lamp lighting device. The degree of freedom in circuit design is increased.
[0024]
Further, since the feedback circuit of the chopper circuit is provided separately from the pair of switching elements, it is not necessary to feed back via the parasitic diode of the switching element, so that the efficiency is improved. Alternatively, since there is no need to connect a feedback diode to the switching element in parallel, there is no need to mount a feedback circuit near the position where the switching elements and their drive circuits are densely packed. The degree is improved.
[0025]
The discharge lamp lighting device of the invention of claim 3 is formed by connecting in parallel a series circuit of a pair of switching elements and a series circuit of a pair of rectifying elements that are alternately switched at a high frequency, and connecting the pair of switching elements. A bridge type rectification / conversion circuit in which a low frequency AC power source is connected between an AC input end formed between a point and a connection point of a pair of rectifying elements; and a low frequency between the AC input ends of the bridge type rectification / conversion circuit An inductor connected in series with an AC power source, a feedback circuit that feeds back an electromotive force generated in the inductor, and a chopper circuit including at least one of a pair of switching elements as a constituent element; between the DC output terminals of the bridge-type rectification / conversion circuit A smoothing capacitor connected and charged by a feedback circuit; a resonance circuit that resonates with a high-frequency voltage; and a resonance current of the resonance circuit There a discharge lamp that lights are applied; is characterized in that it comprises a.
[0026]
In the present invention, the smoothing capacitor is charged by the back electromotive force of the inductor via the feedback circuit, and the smoothing capacitor is connected between the DC output terminals of the bridge type rectification / conversion circuit. It is characteristic in comparison. Therefore, the smoothing capacitor acts as a DC power source for generating a high frequency with respect to the series circuit of the pair of switching elements, so that the discharge lamp as a load is turned on using the high frequency generated by using the charging charge of the smoothing capacitor as a power source. It is configured to be capable of high frequency power supply.
[0027]
When used as a high-frequency power source, the discharge lamp allows various connection modes as shown below, for example. (1) A mode in which an AC input terminal of a bridge-type rectification / conversion circuit is connected to both ends of an inductor that also serves as an output transformer, for example. (2) A mode in which the inductor and the low-frequency AC power supply are connected in series. (3) A mode in which a half-bridge inverter including a pair of switching elements using a smoothing capacitor as a power source is configured and connected to the output terminal.
[0028]
Thus, in the present invention, the magnetic energy stored in the inductor is transferred to the electrostatic energy of the smoothing capacitor without going through the pair of switching elements, and this is used as a power source for generating high frequency, Moreover, the degree of freedom in circuit design is increased.
[0029]
Further, since the smoothing capacitor charging circuit does not exist before the pair of switching elements starts high-frequency switching, inrush current does not occur when the low-frequency AC power supply is turned on. For this reason, a margin arises in power supply capacity and wiring capacity.
[0030]
A discharge lamp lighting device according to a fourth aspect of the present invention is formed by connecting in parallel a series circuit of a pair of switching elements and a series circuit of a pair of rectifying elements that are alternately switched at a high frequency, and connecting the pair of switching elements. A bridge type rectification / conversion circuit in which a low frequency AC power source is connected between an AC input end formed between a point and a connection point of a pair of rectifying elements; and a low frequency between the AC input ends of the bridge type rectification / conversion circuit An inductor connected in series with an AC power source, a feedback circuit that feeds back an electromotive force generated in the inductor, and a chopper circuit including at least one of a pair of switching elements as a constituent element; between the DC output terminals of the bridge-type rectification / conversion circuit A smoothing capacitor connected and charged by a feedback circuit; between both ends of the smoothing capacitor and a pair of switching elements; It is characterized in that it comprises a; each pair of rectifying elements inserted in series; a resonance circuit resonates to a high frequency voltage; a discharge lamp in which the resonance voltage of the resonance circuit is turned on is applied.
[0031]
The present invention is different from the invention of claim 3 in that a pair of rectifier elements inserted in series are arranged between both ends of the smoothing capacitor and the pair of switching elements. For this reason, charging / discharging of a smoothing capacitor is performed exactly by a desired path | route.
[0032]
A discharge lamp lighting device according to a fifth aspect of the present invention is the discharge lamp lighting device according to any one of the first to fourth aspects, wherein the feedback circuit is formed by connecting a pair of series circuits of a pair of rectifier elements in parallel, and alternating current input. It is characterized by comprising a bridge type rectifier circuit whose end is connected in parallel to the inductor and whose DC output end is connected between both ends of the smoothing capacitor.
[0033]
The present invention defines the configuration of a feedback circuit including a bridge-type rectifier circuit having four rectifier elements on four sides.
[0034]
A discharge lamp lighting device according to a sixth aspect of the present invention is the discharge lamp lighting device according to any one of the first to fourth aspects, wherein the feedback circuit includes a series circuit of a pair of rectifier elements and a series circuit of a pair of capacitors in parallel. It is characterized by comprising a bridge type rectifier circuit in which an AC input terminal is connected in parallel to an inductor, and a DC output terminal is connected between both ends of a smoothing capacitor.
[0035]
The present invention defines the configuration of a feedback circuit including a bridge type rectifier circuit of a pair of rectifier elements and a pair of capacitors.
[0036]
A discharge lamp lighting device according to a seventh aspect of the present invention is the discharge lamp lighting device according to any one of the first to sixth aspects, wherein the resonance circuit comprises one of a pair of switching elements, a closed circuit of an inductor and a capacitor; The lamp is characterized in that it is transformer coupled to the inductor of the resonant circuit.
[0037]
The present invention defines a preferable circuit configuration of a load circuit of a half bridge circuit mainly including a pair of switching elements. That is, a series circuit of an inductor and a capacitor constitutes a resonance circuit, and the resonance circuit forms a closed circuit with one switching element, thereby constituting a load circuit of a half bridge circuit. Then, the discharge lamp is connected to the load circuit, and is lit by receiving supply of high frequency power from the load circuit.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0039]
1 and 2 show a bridge type rectification / conversion circuit in the discharge lamp lighting device of the present invention, FIG. 1 is a circuit diagram, and FIG. 2 is a waveform diagram conceptually showing a load voltage and a load current. In FIG. 1, AC is a low-frequency AC power supply, L is a load, Q1 and Q2 are a pair of switching elements, and D1 and D2 are a pair of rectifier elements.
[0040]
That is, the bridge type rectification / conversion circuit BRC is formed by connecting a series circuit of a pair of switching elements Q1 and Q2 and a series circuit of a pair of rectification elements D1 and D2 in parallel so as to form a closed circuit in the forward direction. An AC input terminal is between the connection point j1 between the pair of switching elements Q1 and Q2 and the connection point j2 between the pair of rectifying elements D1 and D2.
[0041]
A low-frequency AC power supply AC is connected to the AC input terminals j1 and j2 of the illustrated bridge-type rectification / conversion circuit BRC via a load L in series.
[0042]
Next, the circuit operation of the bridge type rectification / conversion circuit BRC will be described. When the pair of switching elements Q1 and Q2 perform switching operations alternately at a high frequency, the low-frequency AC power supply AC and the rectifier during the half-wave period in which the voltage polarity of the low-frequency AC power supply AC coincides with the forward direction of the rectifier D1. A current flows through the closed circuit of the element D1, the switching element Q1, the load L, and the low-frequency AC power supply AC only when the switching element Q1 is on, and a voltage drop occurs intermittently across the load L. In other words, a high-frequency pulsed low-frequency AC current intermittently flows in one direction from the low-frequency AC power supply AC to the load L.
[0043]
During the half-wave period in which the polarity of the voltage of the low-frequency AC power supply AC is inverted and coincides with the forward direction of the rectifying element D2, the low-frequency AC power supply AC, the rectifying element D2, the switching element Q2, the load L, and the low-frequency AC power supply AC Current flows only when the switching element Q2 is on, and a voltage drop occurs intermittently across the load L. In other words, a high frequency pulsed low frequency alternating current flows intermittently in the opposite direction from the low frequency alternating current power supply AC to the load L. Therefore, if a high frequency component flowing in the AC input terminals j1 and j2 of the bridge type rectification / conversion circuit BRC is extracted and supplied to the load L, the load L can be energized at a high frequency.
[0044]
In FIG. 2, a load L is a resistance, a curve V is a load voltage, and a curve I is a load current. As can be seen from the figure, the load voltage V and the load current I are in phase and the waveform is a sine wave.
[0045]
FIG. 3 is a circuit diagram showing a first embodiment of the discharge lamp lighting device according to the present invention. In the figure, the same parts as those in FIG. The discharge lamp lighting device includes a bridge type rectification / conversion circuit BRC, a chopper circuit BUC, a smoothing capacitor C1, a pair of rectifier elements D7 and D8, a load circuit LC and a discharge lamp DL, and input terminals t1 and t2 are low frequency AC power supplies. Connected to AC, the discharge lamp DL is turned on at high frequency.
[0046]
The bridge type rectification / conversion circuit BRC has the same configuration as that of FIG.
[0047]
The chopper circuit BUC includes an inductor L1, a feedback circuit FBC, and a switching element Q1. The inductor L1 is connected in series with the high-frequency AC power supply AC at the AC input terminals j1 and j2 of the bridge type rectification / conversion circuit BRC. The feedback circuit FBC is composed of a bridge rectifier circuit including four rectifier elements D3 to D6, and AC input terminals j3 and j4 are connected to both ends of the inductor L1.
[0048]
The smoothing capacitor C1 is composed of an electrolytic capacitor, and is connected between the DC output terminals j5 and j6 of the bridge type rectifier circuit of the feedback circuit FBC.
[0049]
The pair of rectifying elements D7 and D8 are interposed between both ends of the smoothing capacitor C1 and the pair of switching elements Q1 and Q2, and define the discharge path of the smoothing capacitor C1.
[0050]
The load circuit LC is configured by a closed circuit formed by connecting the resonance circuit RC to both ends of the switching element Q2. The resonance circuit RC is composed of a series circuit of an inductor L2 and a capacitor C2, and is connected to both ends of the switching element Q2. A capacitor C3 is connected to the position shown in the drawing to form a part of a feedback circuit for a counter electromotive force generated in the inductor L2. The inductor L2 has one end connected to the connection point j1 of the pair of switching elements Q1 and Q2, and the other end connected to one pole of the discharge lamp DL. The capacitor C2 has one end connected to the other end of the discharge lamp DL and the other end connected to the negative electrode of the smoothing capacitor C1.
[0051]
The discharge lamp DL is connected to the load circuit LC in series with the inductor L2.
[0052]
Next, the circuit operation in the present embodiment will be described. When the low-frequency AC power supply AC is turned on, when the pair of switching elements Q1 and Q2 are alternately switched at a high frequency in the forward polarity with respect to the rectifying element D1 of the bridge-type rectifying / converting circuit BRC, the switching element Q1 Is turned on, the low-frequency AC power supply AC → the rectifier element D1 of the bridge-type rectification / conversion circuit BRC → the switching element Q1 → the inductor L1 of the chopper circuit BUC → the current flows through the closed circuit of the low-frequency AC power supply AC, and the electromagnetic energy flows to the inductor L2. Is accumulated.
[0053]
When the switching element Q1 is subsequently turned off, the electromagnetic energy accumulated in the inductor L1 of the chopper circuit BUC is released, and the back electromotive force appears at both ends of the inductor L1. This counter electromotive force causes a current to flow through the closed circuit of the inductor L2, the rectifying element D3 of the feedback circuit FBC, the smoothing capacitor C1, the rectifying element D6 of the feedback circuit FBC, and the inductor L1, and the smoothing capacitor C1 is charged.
[0054]
In the above circuit operation, the chopper circuit BUC operates as a step-up chopper, so that the charging voltage of the smoothing capacitor C1 is higher than the voltage drop of the inductor L1 although it is proportional to the on-duty.
[0055]
On the other hand, the charge of the smoothing capacitor C1 is discharged as described below. Then, the pair of switching elements Q1 and Q2 and the load circuit LC operate as a half-bridge inverter to light the discharge lamp DL at a high frequency. That is, when the switching element Q1 is turned on, the discharge current of the smoothing capacitor C1 flows through the closed circuit of the smoothing capacitor C1, the rectifying element D7, the switching element Q1, the inductor L2, the discharge lamp DL, the capacitor C2, and the smoothing capacitor C1, and the inductor L2 Electromagnetic energy is accumulated.
[0056]
Next, when the switching element Q1 is turned off, a back electromotive force is generated in the inductor L2, and a current flows through the inductor L2, the discharge lamp DL, the capacitor C2, the rectifying element D6 of the feedback circuit FBC, and the closed circuit of the inductor L2, and the inductor L2 The accumulated electromagnetic energy is released, and electric charge is accumulated in the capacitor C2.
[0057]
Subsequently, when the switching element Q2 is turned on, the electric charge accumulated in the capacitor C2 is released, and a current flows through the closed circuit of the capacitor C2, the discharge lamp DL, the inductor L2, the switching element Q2, the rectifying element D8, and the capacitor C2.
[0058]
Due to the above circuit operation, the discharge lamp DL is turned on at a high frequency because a high-frequency alternating current flows there.
[0059]
Next, the polarity of the low-frequency AC voltage is inverted to become a forward polarity with respect to the rectifying element D2 of the bridge-type rectifying / converting circuit BRC, and the pair of switching elements Q1 and Q2 perform switching at high frequencies alternately. When the switching element Q2 is turned on, a current flows through a closed circuit of the low frequency AC power source AC, the inductor L1 of the chopper circuit BUC, the switching element Q2, the rectifier element D2 of the bridge type rectification / conversion circuit BRC, Electromagnetic energy is accumulated in the inductor L2.
[0060]
When the switching element Q2 is turned off following the above, the electromagnetic energy accumulated in the inductor L1 of the chopper circuit BUC is released, and the back electromotive force appears at both ends of the inductor L1. Due to this back electromotive force, a current flows through the closed circuit of the inductor L2, the rectifying element D5 of the feedback circuit FBC, the smoothing capacitor C1, the rectifying element D4 of the feedback circuit FBC, and the inductor L1, and the smoothing capacitor C1 is charged.
[0061]
In the above circuit operation, the chopper circuit BUC operates as a step-up chopper, so that the charging voltage of the smoothing capacitor C1 is higher than the voltage drop of the inductor L1 although it is proportional to the on-duty.
[0062]
On the other hand, the charge of the smoothing capacitor C1 is discharged in the same manner as described above.
[0063]
FIG. 4 is a circuit diagram showing a second embodiment of the discharge lamp lighting device according to the present invention. In the figure, the same parts as those in FIG. This embodiment is different in that there is no capacitor C3.
[0064]
FIG. 5 is a circuit diagram showing a third embodiment of the discharge lamp lighting device of the present invention. In the figure, the same parts as those in FIG. This embodiment is different in that the discharge lamp DL is turned on via the inductor L1 of the feedback circuit FBC.
[0065]
That is, the inductor L1 of the feedback circuit FBC constitutes the output transformer OT, and the discharge lamp DL is connected to the secondary winding of the output transformer OT. Capacitor C2 is connected between inductor L1 and switching element Q2 so as to form a closed circuit of switching element Q2, inductor L1, and capacitor C2. Further, a capacitor C3 is connected to the position shown in the figure.
[0066]
Thus, in the third embodiment, the discharge lamp DL is lit by the high-frequency current flowing from the low-frequency AC power supply AC and the high-frequency current that flows due to the discharge of the charge of the smoothing capacitor C1. Note that the high-frequency current flowing from the low-frequency AC power supply AC and the high-frequency current that flows due to the discharge of the charge of the smoothing capacitor C1 flow in essentially the same manner as in the first embodiment shown in FIG.
[0067]
【The invention's effect】
According to each of the first to seventh aspects of the present invention, a discharge lamp having a neutral point step-down non-inverting inverter that switches a positive and negative polarity low-frequency AC power supply voltage at a high frequency, having a simple circuit configuration and less harmonics is provided. A lighting device can be provided.
[0068]
According to the invention of claim 1, in addition, the inductor only needs to have an impedance effective only for the high-frequency current due to switching of the switching element, and thus the low-frequency AC power supply operates without being substantially short-circuited. Therefore, it is possible to provide a discharge lamp lighting device in which the inductor of the chopper circuit is reduced in size and weight.
[0069]
According to the invention of claim 2, in addition, the inductor of the chopper circuit is connected in series with the low-frequency AC power source between the AC input terminals of the bridge type rectification / conversion circuit, thereby providing a feedback circuit, a smoothing capacitor, and a load. It is possible to develop various connection positions and circuit configurations of the discharge lamp, etc., increasing the degree of freedom in circuit design as a discharge lamp lighting device, and arranging the feedback circuit of the chopper circuit separately from the pair of switching elements. Therefore, since there is no need to feed back via the parasitic diode of the switching element, the efficiency is improved, and there is no need to connect a feedback diode in parallel to the switching element. Since there is no need to mount a feedback circuit near the location where circuits are densely packed, Degree can provide a discharge lamp lighting apparatus improves.
[0070]
According to the third aspect of the present invention, the magnetic energy stored in the inductor is provided by connecting the DC output terminal of the bridge type rectification / conversion circuit and the smoothing capacitor charged by the feedback circuit. Is transferred to the electrostatic energy of the smoothing capacitor without passing through a pair of switching elements, and this is used as a power source for generating high frequency, so that the efficiency of the circuit design is increased and the charging circuit for the smoothing capacitor is increased. Since a pair of switching elements do not exist before the start of high-frequency switching, no inrush current occurs when the low-frequency AC power supply is turned on. Can be provided.
[0071]
According to the invention of claim 4, in addition to being connected between the DC output terminals of the bridge type rectification / conversion circuit, between the smoothing capacitor charged by the feedback circuit, both ends of the smoothing capacitor and the pair of switching elements. By providing a pair of rectifying elements inserted in series, it is possible to provide a discharge lamp lighting device in which charging and discharging of the smoothing capacitor is accurately performed in a desired path.
[0072]
According to the invention of claim 5, in addition, the feedback circuit comprises a pair of series circuits of a pair of rectifying elements connected in parallel, the AC input terminal is connected in parallel to the inductor, and the DC output terminal is both terminals of the smoothing capacitor. A discharge lamp lighting device comprising a bridge-type rectifier circuit connected therebetween can be provided.
[0073]
According to the invention of claim 6, in addition, the feedback circuit is formed by connecting a series circuit of a pair of rectifying elements and a series circuit of a pair of capacitors in parallel, the AC input terminal is connected in parallel to the inductor, and the DC output terminal Can provide a discharge lamp lighting device comprising a bridge type rectifier circuit connected between both ends of a smoothing capacitor.
[0074]
According to the seventh aspect of the present invention, there is provided a discharge lamp lighting device in which the resonance circuit comprises a closed circuit of one of a pair of switching elements, an inductor and a capacitor, and the discharge lamp is transformer-coupled to the inductor of the resonance circuit. can do.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a bridge type rectification / conversion circuit in a discharge lamp lighting device according to the present invention.
FIG. 2 is a waveform diagram conceptually showing the load voltage and load current as well.
FIG. 3 is a circuit diagram showing a first embodiment of a discharge lamp lighting device according to the present invention.
FIG. 4 is a circuit diagram showing a second embodiment of the discharge lamp lighting device of the present invention.
FIG. 5 is a circuit diagram showing a third embodiment of the discharge lamp lighting device according to the present invention.
[Explanation of symbols]
BEC: Bridge type rectification / conversion circuit, BUC: Chopper circuit, C1: Smoothing capacitor, D1 to D8: Rectifier, DL: Discharge lamp, FBC: Feedback circuit, L1, L2: Ink, LC: Load circuit, Q1, Q2: Switching element, RC: Resonance circuit

Claims (7)

A series circuit of a pair of switching elements that alternately switch at a high frequency and a series circuit of a pair of rectifier elements are formed in parallel, and between the connection point of the pair of switching elements and the connection point of the pair of rectifier elements A bridge type rectification / conversion circuit in which a low-frequency AC power source is connected between AC input terminals formed on
At least one of an inductor inserted at a position on the circuit in which both the low-frequency alternating current and the high-frequency current of the bridge-type rectification / conversion circuit flow bidirectionally, a feedback circuit that feeds back the counter electromotive force generated in the inductor, and a pair of switching elements A chopper circuit including one;
A resonant circuit that resonates with a high frequency voltage;
A discharge lamp which is turned on when a resonance voltage of the resonance circuit is applied;
A discharge lamp lighting device comprising: A series circuit of a pair of switching elements that alternately switch at a high frequency and a series circuit of a pair of rectifier elements are formed in parallel, and between the connection point of the pair of switching elements and the connection point of the pair of rectifier elements A bridge type rectification / conversion circuit in which a low-frequency AC power source is connected between AC input terminals formed on
An inductor connected in series with a low-frequency AC power supply between AC input terminals of a bridge type rectifier / converter circuit, a feedback circuit that feeds back a counter electromotive force generated in the inductor, and a chopper circuit including at least one of a pair of switching elements as components When;
A resonant circuit that resonates with a high frequency voltage;
A discharge lamp which is turned on when a resonance voltage of the resonance circuit is applied;
A discharge lamp lighting device comprising: A series circuit of a pair of switching elements that alternately switch at a high frequency and a series circuit of a pair of rectifier elements are formed in parallel, and between the connection point of the pair of switching elements and the connection point of the pair of rectifier elements A bridge type rectification / conversion circuit in which a low-frequency AC power source is connected between AC input terminals formed on
An inductor connected in series with a low-frequency AC power supply between AC input terminals of a bridge type rectifier / converter circuit, a feedback circuit that feeds back a counter electromotive force generated in the inductor, and a chopper circuit including at least one of a pair of switching elements as components When;
A smoothing capacitor connected between the DC output terminals of the bridge-type rectification / conversion circuit and charged by a feedback circuit;
A resonant circuit that resonates with a high frequency voltage;
A discharge lamp which is turned on when a resonance voltage of the resonance circuit is applied;
A discharge lamp lighting device comprising: A series circuit of a pair of switching elements that alternately switch at a high frequency and a series circuit of a pair of rectifier elements are formed in parallel, and between the connection point of the pair of switching elements and the connection point of the pair of rectifier elements A bridge type rectification / conversion circuit in which a low-frequency AC power source is connected between AC input terminals formed on
An inductor connected in series with a low-frequency AC power supply between AC input terminals of a bridge type rectifier / converter circuit, a feedback circuit that feeds back a counter electromotive force generated in the inductor, and a chopper circuit including at least one of a pair of switching elements as components When;
A smoothing capacitor connected between the DC output terminals of the bridge-type rectification / conversion circuit and charged by a feedback circuit;
A pair of rectifying elements each inserted in series between both ends of the smoothing capacitor and the pair of switching elements;
A resonant circuit that resonates with a high frequency voltage;
A discharge lamp which is turned on when a resonance voltage of the resonance circuit is applied;
A discharge lamp lighting device comprising: The feedback circuit is composed of a bridge type rectifier circuit in which a pair of series circuits of a pair of rectifier elements are connected in parallel, an AC input terminal is connected in parallel to an inductor, and a DC output terminal is connected between both ends of a smoothing capacitor. The discharge lamp lighting device according to any one of claims 1 to 4, wherein The feedback circuit is a bridge in which a series circuit of a pair of rectifying elements and a series circuit of a pair of capacitors are connected in parallel, the AC input terminal is connected in parallel to the inductor, and the DC output terminal is connected between both ends of the smoothing capacitor. The discharge lamp lighting device according to any one of claims 1 to 4, comprising a rectifier circuit. The resonant circuit comprises a closed circuit of one of a pair of switching elements, an inductor and a capacitor;
The discharge lamp is transformer coupled to the inductor of the resonant circuit;
The discharge lamp lighting device according to any one of claims 1 to 6.

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