JP2005124374A - High frequency inverter and discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high frequency inverter in which a pair of switching elements having identical characteristics is employed, and a high frequency output voltage is switched by selecting chopper operation, and also to provide a discharge lamp lighting device employing it. <P>SOLUTION: The high frequency inverter comprises: a bridge type rectifying/converting circuit BRC provided with switching elements Q1, Q2 and rectifying elements D1, D2; a chopper circuit BCH provided with a feedback circuit FBC having an inductor L1 inserted in series with AC input terminals at a position of the circuit where a low frequency AC current and a high frequency AC current flow bidirectionally, and first and second feedback circuit elements FB1, FB2, and the switching elements Q1, Q2; a switching means SW selecting any one of a first mode where the feedback circuit FBC is connected in parallel with the inductor L1 or a second mode where the feedback circuit is connected in parallel with the series section of the inductor L1 and the low frequency AC power supply AC; and third and fourth rectifying elements D5 and D6. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a high-frequency inverter device including a pair of switching elements connected in series and a discharge lamp lighting device including the same.

For example, a passive filter system, an active filter system (for example, refer to Non-Patent Document 1) and a harmonic countermeasure 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. It is divided into partial smoothing methods. The active filter method includes a chopper method, a charge pump method, and a charge pump + chopper method.
“Journal of the Illuminating Science Society”, Vol. 84, No. 5, May 2000, pp. 273-280 “Analysis of the operation of an inverter-type lighting circuit combined with a chopper”

  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.

  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.

  The partial smoothing circuit cannot satisfy the recent strict input current harmonic standards.

  The present invention includes a high-frequency inverter device that includes a neutral point step-down non-inverting inverter, can use a pair of switching elements having the same characteristics, and can switch a high-frequency output voltage between high and low by selecting a chopper operation, and An object of the present invention is to provide a discharge lamp lighting device using the same.

    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; Are generated in the inductor and the first feedback circuit element for feeding back the counter electromotive force of the first polarity generated in the inductor at a position on the circuit where both of them are flowing in both directions in series with the AC input terminal. A feedback circuit having a second feedback circuit element that feeds back a counter electromotive force having a second polarity opposite to the first polarity, and a chopper provided with the pair of switching elements A first mode in which the first and second feedback circuit elements of the chopper circuit are connected in parallel to the inductor, and a second mode in which the first part is connected in parallel to the series part of the inductor and the low-frequency AC power supply. Possible switching means; a third rectifier element interposed between the output end of the first feedback circuit element of the feedback circuit in the chopper circuit and one end of the series circuit of the pair of switching elements, and the second of the feedback circuit And a fourth rectifying element interposed between the output terminal of the feedback circuit element and the other end of the series circuit of the pair of switching elements.

  In the present invention and each of the following inventions, the definitions and technical meanings of terms are as follows unless otherwise specified.

  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.

  <Bridge type rectification / conversion circuit> The bridge type rectification / conversion circuit rectifies low-frequency alternating current and converts it into direct current, and also converts direct current into high frequency by switching. Operates as an inverter. 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.

  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.

  The low-frequency AC power supply may be connected independently between the AC input terminals of the bridge type rectification / conversion circuit, or connected in series with a load and other circuit components such as an inductor and / or discharge lamp of a chopper circuit. May be.

  <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. Then, a boost chopper-like operation is performed by a circuit configuration described below. That is, in the present invention, the chopper circuit includes an inductor, a feedback circuit, and a pair of switching elements.

  The inductor may be dedicated to the chopper or may also serve as the output transformer.

  The feedback circuit performs an action for feeding back the counter electromotive force, and includes first and second feedback circuit elements. The first feedback circuit element feeds back the counter electromotive force having the first polarity generated in the inductor. The second feedback circuit element feeds back a counter electromotive force having a second polarity opposite to the first polarity generated in the inductor. Also, the first and second feedback circuit elements are opposite in polarity but allow a common circuit configuration. For example, a first configuration in which a pair of rectifying elements are connected in series so that their polarities are opposite to each other, a second configuration including a series circuit of a rectifying element and a smoothing capacitor, and a third configuration including a series circuit of a rectifying element and a small-capacitance capacitor It consists of the following. The first feedback circuit element operates when the low-frequency AC voltage has one polarity. The second feedback circuit element operates when the low frequency alternating voltage is in the other polarity. The “smoothing capacitor” in the second configuration is a capacitor having a relatively large capacitance and substantially exhibiting a smoothing action that is substantially completely smooth or partially smooth with respect to a low-frequency AC voltage. Say. In addition, the “small capacitor” in the third configuration has a relatively small capacitance and substantially exhibits a smoothing action that is almost completely smooth or partially smooth with respect to a low-frequency AC voltage. A capacitor that does not.

  The pair of switching elements is also used as a pair of switching elements of a bridge type rectification / conversion circuit. Then, one switching element acts to generate a counter electromotive force by abruptly cutting off the current flowing through the inductor by turning off from the ON state when the low frequency AC voltage has one polarity. The other switching element acts in the same manner as described above when the other polarity is applied.

  <Switching means> The switching means includes a first aspect in which the first and second feedback circuit elements of the chopper circuit are connected in parallel to the inductor, and a second aspect in which the inductor and the low-frequency AC power supply are connected in parallel to the series portion. It is a means which makes any one of these selectable. The switching may be performed by mechanical switching, for example, switching of a mechanical contact, or may be performed by contactless switching by an electronic circuit.

  The switching means may be configured to be operated by a user, or may be configured to be operated by a non-user such as a manufacturer. In the former case, it is convenient that the operation is possible from the outside of the high-frequency inverter device. For example, in a configuration in which the connection is changed by a changeover switch, the operation knob can be disposed outside the high-frequency inverter device. In the latter case, the circuit board on which the high-frequency inverter is mounted can be switched between the first and second modes, for example, the electric circuit component insertion hole so as to correspond to the first and second modes, respectively. Can be configured in such a manner that the two types of electrical circuit component insertion holes can be switched to the two types of circuit connections by jumper wires. Furthermore, a semi-fixed changeover switch can be arranged inside the high-frequency inverter device.

  <About the 3rd and 4th rectification element> The 3rd and 4th rectification element has connected between the chopper circuit and the series circuit of a pair of switching element. That is, the third rectifying element is interposed between the output terminal of the first feedback circuit element and one end of the series circuit of the pair of switching elements. The fourth rectifying element is interposed between the output terminal of the second feedback circuit element and the other end of the series circuit of the pair of switching elements. The third and fourth rectifying elements provide a discharge circuit for outputting the accumulated feedback circuit when the corresponding switching element is turned on. That is, when the first and second feedback circuit elements have capacitors for storing feedback current therein, the output of the feedback circuit is discharged from the feedback circuit. When a smoothing capacitor that accumulates the output of the feedback circuit is connected to the outside of the feedback circuit, the output of the feedback circuit is emitted from the smoothing capacitor.

  The third and fourth rectifying elements prevent the low-frequency AC voltage from flowing into the feedback circuit in the opposite direction to the current rectified by the pair of rectifying elements of the bridge-type rectifying / converting circuit. Acts like

  <Operation of the Present Invention> Since the present invention has the above-described configuration, the low-frequency AC voltage is full-wave rectified and switched at a high frequency in the bridge-type rectification / conversion circuit.・ Step-down converter operation is performed by the conversion circuit.

  In the chopper circuit, a low-frequency alternating current that has been increased in frequency by switching inflow from a low-frequency alternating current power source and a high-frequency current 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.

  In addition, the operation of the chopper circuit differs depending on which of the first and second modes the connection of the feedback circuit to the inductor is. When the first mode is selected by operating the switching means, the back electromotive force of the inductor is fed back to the capacitor as it is. Then, the electric charge accumulated in the capacitor in the feedback circuit element is discharged and converted directly to a high frequency, or transferred from the feedback circuit to a smoothing capacitor and then discharged and indirectly converted to a high frequency. As a result, the high frequency inverter device outputs a relatively low first high frequency voltage.

  On the other hand, when the second mode is selected by operating the switching means, the back electromotive force of the inductor is boosted and fed back by being superimposed on the half-wave voltage of the low-frequency AC voltage. Then, the charge accumulated in the capacitor in the feedback circuit element is discharged and directly converted to high frequency, or further transferred from the feedback circuit to the smoothing capacitor and then discharged and indirectly converted to high frequency. The inverter device outputs a relatively high second high-frequency voltage. In short, the DC voltage fed back to the feedback circuit becomes a boosted value higher than the half-wave voltage of the low-frequency AC voltage or a value not boosted depending on the selection of the circuit connection mode by the switching means.

  In the present invention, since the feedback circuit of the chopper circuit is arranged separately from the pair of switching elements, even if an FET is used as the switching element, it is not necessary to feed back via the parasitic diode. Increased efficiency. 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.

  Furthermore, since the magnetic energy stored in the inductor is converted into direct current energy without passing through a pair of switching elements, and this is used as a power source for generating high frequency, the efficiency is high and the degree of freedom in circuit design is increased.

<Other Configurations> Although not an essential component of the present invention, a more practical high-frequency inverter device and a discharge lamp lighting device using the same can be obtained by adding the following configuration.
1. (Regarding Resonant Circuit) The resonant circuit resonates with a high-frequency voltage formed by alternating switching of a pair of switching elements to provide a load circuit of the high-frequency inverter device. The resonant circuit 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 load, for example, a discharge lamp, and promotes the start by applying this to the load, and shapes the waveform of the high-frequency voltage into a sine wave. .
2. (High-frequency noise filter circuit) The high-frequency noise filter circuit is a circuit means for preventing high-frequency noise generated by the operation of the high-frequency inverter device from flowing out to the low-frequency AC power supply side. A series-parallel connection can be made between the ends.
3. (Smoothing Capacitor) By connecting a smoothing capacitor in parallel between the output terminals of the first and second feedback circuit elements of the feedback circuit, the feedback output of the feedback circuit can be temporarily stored. Then, when one of the pair of switching elements is turned on, the accumulated charge is released and converted into a high frequency. The smoothing capacitor is allowed to be disposed regardless of whether or not a capacitor such as a small-capacitance capacitor is included in the first and second feedback circuit elements of the feedback circuit. And by providing the smoothing capacitor, the ripple component of the envelope waveform of the high frequency voltage applied to the load can be reduced.

    According to a second aspect of the present invention, there is provided a discharge lamp lighting device comprising: the high frequency inverter device according to the first aspect; and a discharge lamp connected between output terminals of the high frequency inverter device.

  The discharge lamp operates as a load of a discharge lamp lighting device mainly composed of a high-frequency inverter device. Any type of discharge lamp may be used. For example, a low pressure discharge lamp such as a fluorescent lamp or a high pressure discharge lamp such as a metal halide lamp may 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 in which the inductor of the chopper circuit is all or part of one of the resonance elements is formed by sharing a part of the bridge type rectification / conversion circuit, and a discharge lamp is connected in parallel or in series with the inductor. Can be connected. 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.

For example, the discharge lamp allows various connection modes as described below.
(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 small-capacitance capacitor as a power source is configured and connected to the output terminal.

  Thus, in the present invention, when the low-frequency AC power supply is turned on, the low-frequency AC voltage is rectified and smoothed by the bridge-type rectification / conversion circuit and the chopper circuit, further converted into a high-frequency voltage and applied to the discharge lamp. Therefore, the discharge lamp is lit at high frequency.

  Although not an essential component of the present invention, an igniter can be added if desired. An igniter is used for starting a discharge lamp when the resonance voltage by the resonance circuit of the load circuit is insufficient, and is provided separately from the discharge circuit in a discharge lamp lighting device mainly composed of a high-frequency inverter. Can be connected to the discharge circuit so that a high voltage pulse generated from is applied to the discharge lamp.

    According to the first aspect of the present invention, the high-frequency voltage is provided with the neutral point step-down non-inverting inverter that switches the positive and negative polarity low-frequency AC power supply voltage at a high frequency and boosted by superimposing the feedback voltage on the low-frequency AC voltage. And a high-frequency voltage without boosting can be switched and output as desired. Therefore, since it is possible to apply an appropriate high-frequency voltage by switching between high and low according to the type and characteristics of the load, a high-frequency inverter device suitable for various applications can be obtained.

  In addition, since a pair of switching elements having the same characteristics can be used, an inexpensive high-frequency inverter device can be provided.

    According to invention of Claim 2, the discharge lamp lighting device which has the effect by Claim 1 can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

    FIG. 1 is a circuit diagram showing a first embodiment for implementing a high-frequency inverter device and a discharge lamp lighting device of the present invention. In the figure, the high frequency inverter device HFI includes a bridge type rectification / conversion circuit BRC, a chopper circuit BCH, a selection means SW, a smoothing capacitor C1, third and fourth rectifying elements D5 and D6, and resonance capacitors C2 and C3. The discharge lamp lighting device DLO includes a high frequency inverter device HFI and a discharge lamp DL, and lights the discharge lamp DL at high frequency. AC is a low frequency AC power source.

  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 end is between the connection point j1 of the pair of switching elements Q1 and Q2 and the connection point j2 of the pair of rectifying elements D1 and D2. A low-frequency AC power supply AC is connected in series with an inductor L1 (described later) and a discharge lamp DL as a load to AC input terminals j1 and j2 of the bridge type rectification / conversion circuit BRC shown in the figure.

  The chopper circuit BCH includes an inductor L1, a feedback circuit FBC, and a pair of switching elements Q1 and Q2. The inductor L1 is connected in series with the low frequency AC power supply AC and the discharge lamp DL between the AC input terminals j1 and j2 of the bridge type rectification / conversion circuit BRC. The feedback circuit FBC includes first and second feedback circuit elements FB1 and FB2. The first feedback circuit element FB1 is formed by connecting a pair of rectifying elements D3 and D7 in reverse polarity in series. The anode of the rectifying element D7 is connected to the end on the discharge lamp DL side that is the load of the inductor L1. The anode of the rectifying element D3 is connected to switching means SW described later. Note that the cathode of the diode D7 is connected to the cathode of the diode D3 to form one feedback output terminal t1 of the feedback circuit FBC. The second feedback circuit element FB2 is also formed by connecting a pair of rectifying elements D4 and D8 in reverse polarity in series. The rectifier element D8 has a cathode connected to the end of the inductor L1 on the discharge lamp DL side. Further, the cathode of the rectifying element D4 is connected to switching means SW described later. The anode of the diode D8 is connected to the anode of the diode D4 to form the other feedback output terminal t2 of the feedback circuit FBC.

  The switching means SW includes a pair of changeover switches SW1 and SW2, and the anode of the rectifying element D3 of the first feedback circuit element FB1 and the cathode of the rectifying element D4 of the second feedback circuit element FB2 are connected to the inductor L1. The other end and the end on the non-inductor L1 side of the low-frequency AC power supply AC are selectably connected. That is, the pair of changeover switches SW1 and SW2 have a movable contact a and a pair of changeover fixed contacts b and c. In the changeover switch SW1, the movable contact a is the anode of the rectifying element D3 of the first feedback circuit element FB1, the switching fixed contact b is the other end of the inductor L1, and the switching fixed contact c is the non-inductor L1 side of the low-frequency AC power supply AC. Are connected to the end of each. In the changeover switch SW2, the movable contact a is the cathode of the rectifying element D4 of the second feedback circuit element FB2, the switching fixed contact b is the other end of the inductor L1, and the switching fixed contact c is the non-inductor L1 side of the low-frequency AC power supply AC. Are connected to the end of each.

  The smoothing capacitor C1 is connected to a pair of feedback output terminals t1 and t2 of the feedback circuit FBC.

  The third and fourth rectifying elements D5 and D6 are interposed in the forward direction between the pair of feedback output terminals t1 and t2 of the feedback circuit FBC and the pair of switching elements Q1 and Q2.

  The resonant capacitors C2 and C3 are connected to the illustrated positions that form a series resonant circuit with the inductor L1 with respect to the high-frequency voltage.

  Next, circuit operation in this embodiment will be described.

  The circuit operation of the bridge type rectification / conversion circuit BRC is as follows. That is, when the low-frequency AC power supply AC is turned on and the pair of switching elements Q1 and Q2 perform switching operations alternately at a high frequency, the period in which the voltage polarity of the low-frequency AC power supply AC coincides with the forward direction of the rectifying element D1. Therefore, during the half-wave period in which the connection point j2 is positive, the low-frequency AC power supply AC, the rectifying element D1, one switching element Q1, the discharge lamp DL, the inductor L1 of the chopper circuit BCH, and the closed circuit of the low-frequency AC power supply AC A current flows when one of the switching elements Q1 is on, and a voltage drop occurs intermittently across the load L. In other words, a high frequency pulsed low frequency alternating current intermittently flows in one direction from the low frequency alternating current power supply AC to the discharge lamp DL.

  The operation of the chopper circuit FBC is as follows. First, the case where the switching means SW is in the illustrated position will be described. That is, in the above switching operation of one switching element Q1, the current flowing through the inductor L1 of the chopper circuit BCH increases linearly during the period when one switching element Q1 is on. Next, when one switching element Q1 is turned off, a counter electromotive force is generated in the inductor L1 so as to continue the current flowing therethrough. Then, the closed circuit of the inductor L1, the low-frequency AC power supply AC, the first rectifier element D3 in the first feedback circuit element FB1, the smoothing capacitor C1, the sixth rectifier element D of the second feedback circuit element FB2, and the inductor L1. A current flows through the inside, and the smoothing capacitor C1 is charged. At this time, since the low-frequency AC power supply AC has a polarity in which the first rectifying element D3 is in the forward direction, the smoothing capacitor C1 is in a state where a half-wave voltage in the polarity of the low-frequency AC power supply AC is superimposed, in other words In this case, the battery is charged in a state where it is boosted by a half wave of the low-frequency AC voltage.

  Next, when one switching element Q1 is turned on again, the charge of the smoothing capacitor C1 is the smoothing capacitor C1, the third rectifying element D5, the switching element Q1, the discharge lamp DL, the inductor L1, the resonant capacitor C3, and the smoothing capacitor C1. It flows as a high-frequency current in a closed circuit consisting of At this time, since the voltage of the smoothing capacitor C1 is boosted in advance by being superimposed on the half-wave voltage of the low-frequency AC power supply AC, the generated high-frequency voltage is also boosted.

  Now, during the 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, that is, during the half wave period in which the connection point j1 is positive, the other switching element Q2 is turned on. A current flows in the closed circuit of the frequency AC power supply AC, inductor L1, discharge lamp DL, the other switching element Q2, rectifier element D2, and low frequency AC power supply AC, and a voltage drop occurs intermittently across the discharge lamp DL. In other words, a high frequency pulsed low frequency alternating current intermittently flows in the opposite direction from the low frequency alternating current power supply AC to the discharge lamp DL. Therefore, since the high frequency component flowing between the AC input terminals j1 and j2 of the bridge type rectification / conversion circuit BRC is supplied to the discharge lamp DL, the discharge lamp DL is energized at a high frequency.

  Next, when the other switching element Q2 is turned off, the back electromotive force generated in the inductor L1 of the chopper circuit BCH is superimposed on the half-wave voltage of the low-frequency AC voltage, and the inductor L1, the fifth of the first feedback circuit element FB1. The smoothing capacitor C1 is charged by flowing through the closed circuit of the rectifying element D7, the smoothing capacitor C1, the second rectifying element D4 of the second feedback circuit element FB2, the low-frequency AC power supply AC and the inductor L1. Also at this time, since the half-wave voltage in the reverse direction of the low-frequency AC power supply AC is superimposed, the charging voltage is boosted.

  Thus, in the steady operation state of the high-frequency inverter device, the smoothing capacitor C1 is charged with a value obtained by adding the half-wave voltage of the low-frequency AC voltage to the feedback voltage of the feedback circuit FBC, and thus boosted. When one switching element Q1 is turned on, the charge of the smoothing capacitor C1 is discharged in the closed circuit of the smoothing capacitor C1, the third rectifying element D5, the switching element Q1, the discharge lamp DL, the inductor L1, the resonant capacitor C3, and the smoothing capacitor C1. Thus, a high frequency current of one polarity flows through the discharge lamp DL.

  Next, when the switching element Q1 is turned off and the switching element Q2 is turned on, the charge of the resonance capacitor C3 is changed to the resonance capacitor C3, the inductor L1, the discharge lamp DL, the switching element Q2, the fourth rectifier element D6, and the resonance capacitor C3. The closed circuit is discharged, and a high-frequency current of the other polarity flows through the discharge lamp DL. Therefore, a positive and negative high frequency load current flows through the discharge lamp DL, and a sinusoidal high frequency load voltage appears at both ends of the discharge lamp DL due to the series resonance of the inductor L1 and the resonant capacitor C3. The load voltage at this time is a boosted high-frequency voltage. Therefore, the discharge lamp DL can perform high-frequency lighting with a voltage boosted as required.

  When the switching means SW is operated to bring the movable contact a into contact with the switching fixed contact c, the inductor L1 is connected to the feedback circuit FBC in a state where the low frequency AC power source AC is excluded. Therefore, since the charging voltage of the smoothing capacitor C1 is not boosted, the high frequency voltage is not boosted. At this time, the high frequency voltage is relatively low. On the other hand, as described above, the high-frequency voltage when the half-wave voltage of the low-frequency AC power supply AC is superimposed on the feedback output is relatively high. Therefore, the high-frequency voltage output from the high-frequency inverter device can be switched between high and low by operating the switching means SW.

  Hereinafter, another embodiment for carrying out the present invention will be described with reference to FIGS. In addition, in each figure, the same code | symbol is attached | subjected about the part same as FIG. 1, and description is abbreviate | omitted. In this embodiment, the circuit configuration of the feedback circuit FBC is different.

  That is, in the feedback circuit FBC, the first feedback circuit element FB1 includes a series circuit of the first rectifier element D3 and the first small-capacitance capacitor C4. Similarly, the second feedback circuit element FB2 includes a series circuit of a second rectifier element D4 and a second small-capacitance capacitor C5. The mode of connection between the first and second rectifying elements D3 and D4 and the switching means SW is the same as in the first mode.

  Next, the circuit operation will be described mainly with respect to differences from the first embodiment shown in FIG. That is, in one half wave in which the polarity of the low-frequency AC voltage is positive at the connection point j2, the inductor L1, the first rectifier element D3, the first small-capacitance capacitor C4, and the inductor are caused by the counter electromotive force of the inductor L1. A feedback current flows in the closed circuit of L1, and the first small capacitor C4 is charged. At the same time, a feedback current flows in the closed circuit of the inductor L1, the first rectifying element D3, the smoothing capacitor C1, the second rectifying element D4, and the inductor L1, and the smoothing capacitor C1 is charged.

  In the other half wave in which the polarity of the low-frequency AC voltage is positive at the connection point j1, when the switching element Q1 is turned on, the inductor L1, the second small-capacitance capacitor C5, A feedback current flows in the closed circuit of the rectifying element D4 and the inductor L1, and the second small-capacitance capacitor C4 is charged. At the same time, a feedback current also flows in the closed circuit of the inductor L1, the first small-capacitance capacitor C4, the smoothing capacitor C1, the second rectifying element D4, and the inductor L1, and the smoothing capacitor C1 is charged.

  Next, when the switching element Q1 is turned off, the charge of the smoothing capacitor C1 is discharged in the closed circuit of the smoothing capacitor C1, the third rectifier element D5, the switching element Q1, the discharge lamp DL, the small-capacitance capacitor C5, and the smoothing capacitor C1. Thus, a half wave in one polarity of the high-frequency voltage is applied to the discharge lamp DL. Subsequently, when the switching element Q1 is turned off and the switching element Q2 is turned on, the charge of the small-capacitance capacitor C5 is closed by the small-capacitance capacitor C5, the discharge lamp DL, the switching element Q2, the fourth rectifier element D6, and the small-capacitance capacitor C5. The inside of the circuit is discharged, and a half wave in the other polarity of the high frequency voltage is applied to the discharge lamp DL. Therefore, since the positive and negative half waves of the high frequency voltage are alternately applied to the discharge lamp DL as a load, the discharge lamp DL is lit at a high frequency. The operation of the switching means SW is the same as that in the first embodiment shown in FIG.

    FIG. 3 is a circuit diagram showing a third mode for carrying out the high-frequency inverter device and the discharge lamp lighting device of the present invention. In this embodiment, the first and second rectifying elements in the feedback circuit FBC of the chopper circuit BCH are connected in advance to D3, D4 and D9, and D10, and either one of the groups is selectively selected by the switching means SW. It differs from FIG. 2 in that it is configured to act.

  That is, the first and second rectifying elements D3 and D4 are configured such that the first and second feedback circuit elements FB1 and FB2 are connected in parallel to the series portion of the low-frequency AC power supply AC and the inductor L1. Yes. This configuration corresponds to the case of obtaining a relatively high high-frequency voltage. In contrast, the first and second rectifier elements D9 and D10 are configured such that the first and second feedback circuit elements FB1 and FB2 are connected in parallel only to the inductor L1. For this reason, it corresponds to the case of obtaining a relatively low high-frequency voltage.

    FIG. 4 is a circuit diagram showing a fourth mode for carrying out the high-frequency inverter device and the discharge lamp lighting device of the present invention. In this embodiment, the connection positions of the first and second rectifying elements D3 and D4 and the first and second small-capacitance capacitors C4 and C5 in the feedback circuit FBC of the chopper circuit BCH with respect to the inductor L1 are opposite to each other. 2 differs from the first embodiment shown in FIG. 2 in that the discharge lamp DL, which is a load, is configured to be energized via the inductor L1. .

  Also in this embodiment, the circuit operation is substantially the same as that in the first embodiment shown in FIG. However, the circuit operation of the first and second feedback circuit elements FB1 and FB2 of the feedback circuit FBC is opposite to that of FIG. 2 for the polarity of each half-wave of the low-frequency AC voltage. That is, in the half-wave polarity of the low-frequency AC voltage at which the connection point j2 is positive, the feedback operation for the low-frequency AC current of the input current is mainly handled by the second feedback circuit element FB2, and the connection point j1 is positive. The first feedback circuit element FB1 is mainly responsible for the feedback operation for the low-frequency alternating current of the input current in the half-wave polarity of the low-frequency alternating voltage.

  The first and second small-capacitance capacitors C4 and C5 are connected so as to act in common with respect to the first and second modes. This is the same as the case of the second rectifying elements D3 and D4.

  Further, the inductor L1 of the chopper circuit BCH constitutes an output transformer OT, and a discharge lamp DL as a load is connected to the secondary winding of the output transformer OT. For this reason, the discharge lamp DL is lit by a voltage obtained by transforming the high-frequency voltage appearing across the inductor L1 at a step-up ratio corresponding to the primary: secondary turns ratio of the output transformer OT. Therefore, the secondary voltage applied to the discharge lamp DL as a load can be boosted or lowered to a desired value.

    FIG. 5 is a circuit diagram showing a fifth embodiment of the high frequency inverter device and the discharge lamp lighting device according to the present invention. This embodiment differs from the first embodiment shown in FIG. 1 in that the first and second feedback circuit elements FB1 and FB2 of the feedback circuit BCH are provided with smoothing capacitors C4 and C5, respectively, and the inductor of the chopper circuit BCH L1 constitutes the output transformer OT, and is the same as FIG. 4 in that the discharge lamp DL as a load is connected to the secondary winding of the output transformer OT.

The circuit diagram which shows the 1st form for implementing the high frequency inverter apparatus and discharge lamp lighting device of this invention The circuit diagram which shows the 2nd form for implementing the high frequency inverter apparatus and discharge lamp lighting device of this invention The circuit diagram which shows the 3rd form for implementing the high frequency inverter apparatus and discharge lamp lighting device of this invention The circuit diagram which shows the 4th form for implementing the high frequency inverter apparatus and discharge lamp lighting device of this invention The circuit diagram which shows the 5th form for implementing the high frequency inverter apparatus and discharge lamp lighting device of this invention

Explanation of symbols

      AC: low frequency AC power supply, BCH: chopper circuit, BRC: bridge type rectification / conversion circuit, C1: smoothing capacitor, C2, C3: resonance capacitor, D3: first rectification element, D4: second rectification element , D5... Third rectifier element, D6... Third rectifier element, DL... Discharge lamp, DLO... Discharge lamp lighting device, FB1... First feedback circuit element, FB2. ... Feedback circuit, HFI ... High frequency inverter device, j1, j2 ... Connection point, L1 ... Incrementor, Q1, Q2 ... Switching element, SW ... Switching means, SW1, SW2 ... Changeover switch

Claims (2)

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
Inductor inserted in series between the AC input terminals at the position on the circuit where both low-frequency alternating current and high-frequency current of the bridge-type rectifier / converter circuit flow bidirectionally, and back electromotive force of the first polarity generated in the inductor A feedback circuit having a first feedback circuit element that feeds back and a second feedback circuit element that feeds back a counter electromotive force having a second polarity opposite to the first polarity generated in the inductor; A chopper circuit with a switching element;
Switching capable of selecting one of the first mode in which the first and second feedback circuit elements of the chopper circuit are connected in parallel to the inductor and the second mode in which the inductor and the low-frequency AC power supply are connected in parallel to each other. With means;
A third rectifier element interposed between the output terminal of the first feedback circuit element of the feedback circuit in the chopper circuit and one end of the series circuit of the pair of switching elements, and the output terminal of the second feedback circuit element of the feedback circuit And a fourth rectifying element interposed between the other end of the series circuit of the pair of switching elements;
A high frequency inverter device comprising: A high-frequency inverter device according to claim 1;
A discharge lamp connected between the output terminals of the high-frequency inverter device;
A discharge lamp lighting device comprising:

Images