JP2011249140A - High-pressure discharge lamp lighting device and luminaire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-pressure discharge lamp lighting device which stably drives switching elements even at the end of a dead time, and a luminaire using the same.SOLUTION: The high-pressure discharge lamp lighting device comprises: a full-bridge circuit comprising four switching elements Q1 to Q4 to which DC electric power is input; a load circuit including a high-pressure discharge lamp between output terminals of the full-bridge circuit; a parallel circuit with a first capacitor; and a series circuit with a first inductor, in which the load circuit, the parallel circuit, and the series circuit are connected. A dead time DT is provided in which all the switching elements Q1 to Q4 are turned off each time of the polarity of output is inverted. The dead time DT ends if an absolute value |IL| of a current IL flowing to the first inductor decreases below a predetermined switching threshold Ith during the dead time DT. Vibration generated when the current IL reaches 0 during the dead time DT is prevented, so that the switching elements Q1 and Q3 are stably driven even at the end of the dead time DT.

Description

  The present invention relates to a high-pressure discharge lamp lighting device and a lighting fixture using the same.

Conventionally, a high-pressure discharge lamp lighting device for lighting a high-pressure discharge lamp (HID lamp) using arc discharge in high-pressure metal vapor has been provided (for example, see Patent Document 1).
An example of this type of high pressure discharge lamp lighting device is shown in FIG. This high-pressure discharge lamp lighting device converts a DC power input from an AC power source AC into a full-wave rectification, and converts a DC output (pulsating current output) of the diode bridge DB into a DC power of a predetermined voltage and outputs the DC power. A DC power source 1, a lighting unit 2 that converts DC power output from the DC power source 1 into AC power and outputs the AC power to the high-pressure discharge lamp DL, and a control unit 3 that controls the lighting unit 2 are provided. The DC output terminal on the low voltage side of the diode bridge DB and the output terminal on the low voltage side of the DC power supply 1 are each connected to the ground.

  More specifically, the DC power source 1 includes a series circuit of an inductor L0 and a switching element Q0 connected between the DC output terminals of the diode bridge DB, a diode D0 and an output capacitor C0 connected in parallel to the switching element Q0. Is a well-known boost converter (step-up chopper circuit) that uses the voltage across the output capacitor C0 as an output voltage. The control unit 3 periodically drives the switching element Q0 on and off with an on-duty so as to keep the voltage across the output capacitor C0 (that is, the output voltage of the DC power supply 1) Vdc constant.

  The lighting unit 2 is a so-called full-bridge type inverter circuit, and has two sets of series circuits of two switching elements Q1 to Q4 that are connected between the output terminals of the DC power source unit 2 and constitute a full-bridge circuit. . Each of the switching elements Q1 to Q4 of the lighting unit 2 is, for example, an NMOS and has a parasitic diode (body diode), and the forward direction of the parasitic diode is opposite to the output of the DC power supply 1 ( That is, the source is connected to the lower voltage side than the drain). One end of the high-pressure discharge lamp DL is connected to one of the switching elements Q3 and Q4 of the series circuit via the first inductor L1 (the switching element Q3 on the high voltage side is hereinafter referred to as the third switching element Q3, and the low voltage side The switching element Q4 is connected to a connection point of the fourth switching element Q4 in the following, and the other end of the switching element Q4 is connected to the switching element Q1, Q2 of the other series circuit via the second inductor L2. The voltage side switching element Q1 is hereinafter referred to as a first switching element Q1, and the low voltage side switching element Q2 is hereinafter referred to as a second switching element Q2.) Further, a first capacitor C1 is connected in parallel to a series circuit of the second inductor L2 and the high pressure discharge lamp DL. That is, the second inductor L2 forms a load circuit together with the high pressure discharge lamp DL. The second inductor L2 is a so-called autotransformer provided with a tap, and this tap is connected to the ground via the second capacitor C2. In addition, the lighting unit 2 includes a driving high-side driver 21 for each of the switching elements Q1 and Q3 on the high-voltage side (high-side).

  The control unit 3 directly drives the switching elements Q2 and Q4 on the low voltage side (low side), and drives the switching elements Q1 and Q3 on the high voltage side via the high side driver 21, respectively.

  Hereinafter, the operation of the control unit 3 will be described. When the power is turned on, as shown in FIG. 10, the control unit 3 performs a start operation Ps for causing the high voltage discharge lamp DL to output a high voltage necessary for starting discharge in the high pressure discharge lamp DL from the lighting unit 2. Do. Specifically, the switching elements Q1 to Q4 positioned diagonally to each other are simultaneously turned on and the switching elements Q1 to Q4 connected in series to each other are alternately turned on. Q1 to Q4 are periodically turned on / off. The frequency of this on / off drive is about the resonance frequency (for example, several hundred kHz) of the resonance circuit formed by the second inductor L2 and the second capacitor C2. During this starting operation Ps, the resonance voltage generated at the connection point between the second inductor L2 and the second capacitor C2 is boosted by the second inductor L2 as an autotransformer and output to the high pressure discharge lamp DL. Discharge (that is, lighting) is started in DL. The control unit 3 monitors the voltage across the high-pressure discharge lamp DL (hereinafter referred to as “lamp voltage”) Vla, and the peak value of the absolute value | Vla | of the lamp voltage Vla is lower than the predetermined lighting determination voltage Vsd. Based on this, the lighting of the high pressure discharge lamp DL is detected, and the routine proceeds to a steady operation Pn for maintaining the lighting of the high pressure discharge lamp DL. In FIG. 10, in addition to the output voltage Vdc of the DC power supply 1, the lamp voltage Vla, the on / off states of the switching elements Q1 to Q4 of the lighting unit 2, the input voltage VAC from the AC power supply AC to the DC power supply 1 The current flowing through the high-pressure discharge lamp DL (hereinafter referred to as “lamp current”) Ila is also indicated.

  In the steady operation, the control unit 3 first switches each switching element (for example, the first switching element Q1 and the fourth switching element Q4) of the pair of switching elements Q1 to Q4 positioned diagonally to each other in the lighting unit 2. Turns on and turns off the other switching elements (for example, the second switching element Q2 and the third switching element Q3). Then, as shown in FIG. 11, a current (hereinafter referred to as “circuit current”) IL flowing through the first inductor L1 gradually increases, and energy is stored in the first inductor L1. Thereafter, the control unit 3 turns off one switching element (for example, the fourth switching element Q4) of the set that has been turned on. Then, due to the release of energy from the first inductor L1, the circuit current IL flows into a loop including the parasitic diodes of the switching elements Q1 and Q4 and the output capacitor C0 of the DC power supply 1 that have been turned on immediately before. Decrease. The control unit 3 monitors the circuit current IL by an appropriate current detection means. When the circuit current IL reaches zero, the one switching element (the fourth switching element Q4 in the above example) is turned on again, and the like Is repeated a predetermined number of times. The frequency of the operation (on / off of the fourth switching element Q4 in the above example) is, for example, several tens of kHz. As the current detection means, for example, a current detection resistor or a current transformer can be used. Further, the control unit 3 monitors the lamp voltage Vla, and the lower the lamp voltage Vla, the longer the duration time during which the two switching elements Q1 and Q4 are on (in the above example, the fourth switching element Q4 By making the ON state duration) longer, feedback control is performed so that the lamp voltage Vla becomes a predetermined target voltage.

  After that, there is a possibility that the switching element Q1 to Q4 and the pair maintained in the OFF state may be ON controlled across the dead time DT for maintaining all the switching elements Q1 to Q4 of the lighting unit 2 in the OFF state. Swap the pair. In the above example, the first switching element Q1 and the fourth switching element Q4 are maintained in the off state, and the on / off control as described above is started for the second switching element Q2 and the third switching element Q3. . As a result, the polarities of the circuit current IL and the lamp voltage Vla are inverted, and the same on / off control is repeated a predetermined number of times. For example, the third switching element Q3 is driven on and off while the second switching element Q2 is maintained in the on state. Thereafter, the polarity of the circuit current is reversed by changing the set of the switching elements Q1 to Q4 to be turned on / off again with the dead time interposed therebetween, and the same operation is repeated thereafter. The frequency of inversion of the polarity as described above is, for example, several hundred Hz. Immediately before and immediately after the dead time DT are two switching elements Q1 to Q4 that are positioned diagonally to each other in the lighting unit 2, and two switching elements Q1 to Q4 that are different from each other immediately before and after the dead time DT. Is turned on.

Japanese Patent No. 4341403

  Here, the high-side driver 21 performs switching in a state where the voltage to ground (hereinafter referred to as “middle point voltage”) of the low-voltage side terminals of the switching elements Q1 and Q3 to be driven is less than a predetermined drive lower limit voltage. Some elements Q1 and Q3 cannot be driven. In the case of the lighting unit 2, the voltage corresponding to the above-described midpoint voltage is a ground voltage (hereinafter referred to as “first midpoint voltage”) Vs <b> 1 at the connection point between the first switching element Q <b> 1 and the first capacitor C <b> 1. And a ground voltage (hereinafter referred to as “second midpoint voltage”) Vs2 at a connection point between the third switching element Q3 and the first inductor L1.

  An example of this type of high-side driver 21 is shown in FIG. The high side driver 21 is connected to an input terminal IN connected to the control unit 2, a gate terminal Tg connected to the gates of the switching elements Q1 and Q3 to be driven, and sources of the driving switching elements Q1 and Q3. A source terminal Ts (that is, a midpoint voltage is input) and a power supply terminal Tb that is maintained at a voltage higher than the source terminal Ts by a predetermined drive power supply voltage VB by an appropriate DC power supply (not shown). . Further, it has an RS type flip-flop circuit 21a, and the gate terminal Tg is connected to one of the source terminal Ts and the power supply terminal Tb in accordance with the output of the flip-flop circuit 21a. Although not described in detail, the high-side driver 21 described above is configured such that when the signal level of the signal input to the input terminal IN changes from the L level to the H level, the voltage to the ground of the power supply terminal Tb (that is, the drive power supply voltage VB). A pulse having a voltage value (wave height) Vp proportional to the sum of the voltage and the midpoint voltage is input to the set terminal S of the flip-flop circuit 21a, and the gate terminal Tg is connected to the power supply terminal in accordance with the change in the output of the flip-flop circuit 21a. By connecting to Tb, a potential difference is generated between the gate terminal Tg and the source terminal Ts, whereby the switching elements Q1, Q3 are driven to be turned on. The voltage value Vp of the pulse is expressed as Vp = k (VB + Vs), where k is the proportionality coefficient and Vs is the midpoint voltage. If the minimum pulse voltage value required to change the output of the flip-flop circuit 21a is Vth, when Vp = k (VB + Vs) <Vth, that is, the midpoint voltage Vs is the driving lower limit voltage Vth / If it is smaller than k-VB, the high-side switching elements Q1, Q3 cannot be driven regardless of the output of the control unit 2.

  Although the above drive lower limit voltage is generally a negative value, in the case of the lighting unit 2, the midpoint voltages Vs 1 and Vs 2 usually take either the output voltage Vdc or 0 V of the DC power supply 1, so that switching is performed. The elements Q1 and Q3 cannot be driven.

  However, as shown in FIG. 11, when the circuit current IL reaches 0 during the dead time DT, an oscillating voltage due to the parasitic capacitance and the parasitic inductance existing in the lighting unit 2 is generated. There is a possibility that the switching elements Q1 and Q3 cannot be driven because Vs1 and Vs2 are lower than the drive lower limit voltage. In particular, as described above, the high-side driver 21 generates a pulse when the input from the control unit 3 changes to operate a latch circuit such as the flip-flop circuit 21a, and the output of the latch circuit causes the switching elements Q1 and Q3 to operate. When the ON / OFF state is determined, if the midpoint voltages Vs1 and Vs2 are below the drive lower limit voltage at the timing when the input from the control unit 3 is changed, the midpoint voltages Vs1 and Vs2 are driven immediately after that. Even if the voltage exceeds the lower limit voltage, the switching elements Q1 and Q3 are not turned on until the input from the control unit 3 once returns (for example, to the L level) and changes again.

  The present invention has been made in view of the above reasons, and an object thereof is to provide a high pressure discharge lamp lighting device capable of stably driving a switching element even at the end of a dead time, and a lighting fixture using the same. There is.

  The high-pressure discharge lamp lighting device according to the present invention includes two series circuits connected in parallel to each other between output terminals of a DC power supply, each having a parasitic diode opposite to the direction of the voltage of the DC power supply. A full bridge circuit composed of two series circuits each composed of individual switching elements, and a first bridge connected between a connection point of the switching elements of one of the series circuits and a connection point of the switching elements of the other series circuit. A series circuit of one inductor and a first capacitor; a high-side driver that drives each switching element having one end connected to the output terminal on the high-voltage side of the DC power supply in the full-bridge circuit; And a control unit that drives each of the switching elements of the full bridge circuit through a driver, and includes a high-pressure discharge lamp. A high pressure discharge lamp lighting device having a circuit connected in parallel to the first capacitor, wherein the control unit is positioned diagonally to each other in the full bridge circuit at least during a period when the high pressure discharge lamp is lit. Of switching elements to be turned on, the operation of driving on / off each switching element in the other set with each switching element in one set being kept off is a predetermined set of switching elements to be kept off. When changing the set of switching elements to be kept off, the dead time for keeping all the switching elements of the full bridge circuit in the off state is provided when changing the set of switching elements to be kept off. The high side driver is connected to the output terminal on the high voltage side of the DC power supply in the full bridge circuit. The switching element connected to the other end of the switching element is connected to the ground voltage is less than a predetermined driving lower limit voltage, the switching element cannot be driven regardless of the input from the control unit, The control unit sets the timing for ending the dead time, the lower one of the driving voltage lower limit of the ground voltage to the other end of the switching element having one end connected to the output terminal on the high voltage side of the DC power supply in the full bridge circuit. The timing is before the timing when the voltage is less than the voltage.

  In the above-described high pressure discharge lamp lighting device, it is preferable that the control unit sets the timing at which the dead time is ended to a timing before the timing when the current flowing through the first inductor becomes zero.

  Further, in the above high pressure discharge lamp lighting device, the control unit monitors the current flowing through the first inductor during the dead time, and when the absolute value of the current falls below a predetermined switching threshold, It is desirable to end the time.

  Alternatively, in the above high pressure discharge lamp lighting device, the control unit monitors a voltage at a connection point between the switching element of the full bridge circuit and the first capacitor during the dead time, and a change in the voltage is detected. It is desirable to end the dead time.

  Alternatively, in the above high pressure discharge lamp lighting device, the control unit monitors a voltage at a connection point between the switching element of the full bridge circuit and the first inductor during a dead time, and a change in the voltage is detected. It is desirable to end the dead time.

  In the high pressure discharge lamp lighting device described above, it is desirable that the control unit measures the duration of the dead time and ends the dead time when the duration of the dead time reaches a predetermined upper limit time. .

  In the high pressure discharge lamp lighting device described above, the high pressure discharge lamp lighting device includes voltage detection means for detecting a voltage across the high pressure discharge lamp, and current detection means for detecting a current flowing through the first inductor. The absolute value of the voltage across the high-pressure discharge lamp and the absolute value of the current flowing through the first inductor are detected at the start of time, and the duration of the dead time is detected at the first inductor detected at the start of the dead time. The product of the absolute value of the current flowing through the first inductor and the inductance of the first inductor is divided by the sum of the absolute value of the voltage across the high-pressure discharge lamp detected at the start of the dead time and the output voltage of the DC power supply. Or less than the time obtained.

  The lighting fixture of the present invention includes any one of the above high-pressure discharge lamp lighting devices and a fixture main body that holds the high-pressure discharge lamp lighting device.

  The timing at which the dead time ends is lower than the timing at which the lower of the voltage to ground at the other end of the switching element whose one end is connected to the output terminal on the high voltage side of the DC power supply in the full bridge circuit is less than the drive lower limit voltage. Since it is the previous timing, the high-side driver does not become unable to drive the switching element, and therefore the switching element can be stably driven even at the end of the dead time.

In Embodiment 1, it is explanatory drawing which shows the time change of the on-off state of each switching element Q1-Q4 of a lighting part, circuit current IL, 1st intermediate voltage Vs1, and 2nd intermediate voltage Vs2. In Embodiment 2, it is explanatory drawing which shows the time change of the on-off state of each switching element Q1-Q4 of a lighting part, circuit current IL, and 1st intermediate voltage Vs1. It is explanatory drawing which shows the time change of the on-off state of each switching element Q1-Q4 of a lighting part, circuit current IL, and 2nd intermediate voltage Vs2 in the example of a change same as the above. In Embodiment 3, it is explanatory drawing which shows the time change of the on-off state of each switching element Q1-Q4 of a lighting part, circuit current IL, and 1st intermediate voltage Vs1. It is explanatory drawing which shows the time change of the on-off state of each switching element Q1-Q4 of a lighting part, circuit current IL, and 2nd intermediate voltage Vs2 in the same as the above. It is a perspective view which shows an example of the lighting fixture using the same. It is a perspective view which shows another example of the lighting fixture using the same as the above. It is a perspective view which shows another example of the lighting fixture using the same as the above. It is a circuit block diagram which shows an example of a high pressure discharge lamp lighting device. It is explanatory drawing which shows the time change with the input voltage VAC from an alternating current power supply, the output voltage Vdc of a direct current power supply, the lamp voltage Vla, the lamp current Ila, and the ON / OFF state of each switching element Q1-Q4 of a lighting part in the same as the above. It is explanatory drawing which shows the time change of the on-off state of each switching element Q1-Q4 of a lighting part, and circuit current IL in a prior art example. It is a circuit block diagram showing an example of a high side driver.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  In addition, since the basic composition of each following embodiment is common with the prior art example demonstrated in FIGS. 9-11, the illustration and description about a common part are abbreviate | omitted.

(Embodiment 1)
In the present embodiment, the controller 3 monitors the circuit current IL during the dead time DT, and when the absolute value | IL | of the circuit current IL falls below a predetermined switching threshold Ith as shown in FIG. The dead time DT is terminated. That is, the timing at which the dead time DT ends is the timing before the oscillation of the midpoint voltages Vs1 and Vs2, and this timing is naturally the lower of the midpoint voltages Vs1 and Vs2 is less than the drive lower limit voltage. Is before the timing. Therefore, the high side driver 21 does not become unable to drive the switching elements Q1 and Q3, that is, the switching elements Q1 and Q3 can be stably driven even at the end of the dead time DT.

  Further, when the control unit 3 measures the duration of the dead time DT and the duration of the dead time DT reaches a predetermined upper limit time without the absolute value | IL | of the circuit current IL being lower than the switching threshold Ith. The dead time DT may be terminated. That is, the above upper limit time becomes the upper limit value of the duration of the dead time DT.

(Embodiment 2)
In the present embodiment, the control unit 3 monitors the first midpoint voltage Vs1 during the dead time DT and, as shown in FIG. 2, the control unit 3 detects the first midpoint voltage Vs1 due to the vibration generated when the circuit current IL reaches zero. 1 When the fluctuation of the midpoint voltage Vs1 is detected, the dead time DT is terminated. Specifically, the control unit 3 that performs the above operation can be realized by using, for example, a comparator.

  Even in this embodiment, if the response of the control unit 3 is made sufficiently fast with respect to the period of the vibration, the lower one of the midpoint voltages Vs1 and Vs2 is dead before the timing when it becomes lower than the drive lower limit voltage. It is possible to drive the switching elements Q1 and Q3 stably even when the time DT ends and the dead time DT ends.

  Similar effects can be obtained by using the second midpoint voltage Vs2 as shown in FIG. 3 instead of the first midpoint voltage Vs1.

  Furthermore, if the timing at which the circuit current IL reaches 0 other than the dead time DT is detected based on the fluctuations in the midpoint voltages Vs1 and Vs2, the current detection means for detecting the circuit current IL is not required. be able to.

  In addition, the control unit 3 measures the duration of the dead time DT, and calculates the dead time DT when the duration of the dead time DT reaches a predetermined upper limit time without detecting fluctuations in the midpoint voltages Vs1, Vs2. You may end. That is, the above upper limit time becomes the upper limit value of the duration of the dead time DT.

(Embodiment 3)
In the present embodiment, the control unit 3 detects, for each dead time DT, the circuit current IL (hereinafter referred to as “peak current”) Ip and the ramp voltage Vla at the start of the dead time DT. Based on the peak current Ip and the ramp voltage Vla, the time until the dead time DT is completed (that is, the duration of the dead time DT) is determined.

  By the way, during at least the period until the circuit current IL reaches 0 during the dead time DT, the output capacitor C0 of the DC power source 1, the series circuit of the second inductor L2 and the high-pressure discharge lamp DL, and the first capacitor C1. A current flows through a loop formed by the parallel circuit, the first inductor L1, and the parasitic diodes of the two switching elements Q1 to Q4 positioned diagonally to each other. The voltage across the parallel circuit is substantially equal to the lamp voltage Vla. Accordingly, immediately after the start of the dead time DT, the voltage across the first inductor L1 becomes substantially equal to the sum | Vla | + Vdc of the output voltage Vdc of the DC power supply 1 and the absolute value | Vla | of the lamp voltage Vla. Assuming that the first inductor L1 is an ideal inductor that is obtained by multiplying the change speed of the circuit current IL by the inductance L to be a voltage across the two terminals, the first inductor L1 is in the period until the circuit current IL reaches 0 during the dead time DT. The decrease rate of the circuit current IL is considered to be (| Vla | + Vdc) / L obtained by dividing the sum | Vla | + Vdc by the inductance L of the first inductor L1. Therefore, the time obtained by dividing the peak current Ip, which is the circuit current IL immediately after the start of the dead time DT, by the decrease rate (| Vla | + Vdc) / L | Ip | × L / (| Vla | + Vdc) Is considered to be the time until the circuit current IL reaches 0 during the dead time DT.

  Therefore, in the present embodiment, the duration of the dead time DT is set to the product | Ip | × L of the absolute value | Ip | of the peak current Ip detected at the start of the dead time DT and the inductance L of the first inductor L1. Is obtained by dividing the absolute value | Vla | of the ramp voltage Vla detected at the start of the dead time DT by the sum (| Vla | + Vdc) of the output voltage Vdc of the DC power supply 1 | Ip | × L / (| Vla | + Vdc) or less.

  For example, when the duration of the dead time DT is made to coincide with the above time | Ip | × L / (| Vla | + Vdc), as shown in FIGS. 4 and 5, the circuit current IL almost reaches zero. It is considered that the dead time DT can be ended at the same time. That is, in the present embodiment, the dead time DT ends before the timing when the midpoint voltages Vs1, Vs2 become less than the drive lower limit voltage, so that the high-side driver 21 cannot drive the switching elements Q1, Q3. That is, the switching elements Q1 and Q3 can be stably driven even at the end of the dead time DT.

  Further, an upper limit value and a lower limit value are provided for the duration of the dead time DT, and if the time | Ip | × L / (| Vla | + Vdc) obtained by the above calculation is greater than or equal to the lower limit value and less than or equal to the upper limit value, the dead time When the duration of DT is the time | Ip | × L / (| Vla | + Vdc), and the time | Ip | × L / (| Vla | + Vdc) obtained by the above calculation exceeds the upper limit value. If the duration of the dead time DT is the upper limit value and the time | Ip | × L / (| Vla | + Vdc) obtained by the above calculation is less than or equal to the lower limit value, the duration of the dead time DT is set as the lower limit value. Also good. The above upper limit value is, for example, the time | Ip | × L / (| Vla | when the absolute value | Vla | of the lamp voltage Vla is the smallest as long as it is assumed (for example, immediately after the start of the steady operation Pn). + Vdc). Further, the above lower limit value is sufficiently long (for example, 100 ns to 100 ns) so that the switching elements Q1 to Q4 connected in series with each other are never simultaneously turned on, even if a possible time lag is taken into account. 500 ns) or more, and the absolute value | Vla | of the lamp voltage Vla is equal to or more than the above time | Ip | × L / (| Vla | + Vdc) when the absolute value | Vla | It ’s a good time.

  The various high-pressure discharge lamp lighting devices described in Embodiments 1 to 3 can be used in a lighting fixture 5 as shown in FIGS. Each of the lighting fixtures 5 of FIGS. 6 to 8 includes a fixture body 51 that houses and holds a high-pressure discharge lamp lighting device, and a lamp body 52 that holds a high-pressure discharge lamp DL. Moreover, the lighting fixture 5 of FIG. 6 and the lighting fixture 5 of FIG. 7 are each provided with the feeder 53 which electrically connects the high pressure discharge lamp lighting device (lighting part 2) and the high pressure discharge lamp DL. The lighting fixture 5 in FIG. 6 is a downlight in which both the fixture main body 51 and the lamp body 52 are fixed to the ceiling surface. The lighting fixture 5 in FIG. 7 and the lighting fixture 5 in FIG. This is a spotlight in which a lamp body 52 is swingably attached to an instrument body 51 fixed to an attachment surface. Since various lighting fixtures 5 as described above can be realized by a well-known technique, detailed description thereof is omitted.

DESCRIPTION OF SYMBOLS 1 DC power supply 3 Control part 5 Lighting fixture 21 High side driver C1 1st capacitor | condenser IL Circuit current (Current which flows into 1st inductor L1)
L1 1st inductor L2 2nd inductor (part of load circuit)
Q1 to Q4 switching element Vs1 first intermediate voltage (one end is a voltage to ground of the other end of the switching element Q1 connected to the output terminal on the high voltage side of the DC power supply 1, and the switching elements Q1 and Q2 and the first capacitor C1 Voltage at the connection point)
Vs2 is a second intermediate voltage (one end of which is a voltage to the ground of the other end of the switching element Q3 connected to the output terminal on the high voltage side of the DC power supply 1, and is a connection point between the switching elements Q3 and Q4 and the first inductor L1 Voltage)

Claims (8)

Two series circuits connected in parallel between the output terminals of the DC power supply, each consisting of two switching elements each having a parasitic diode opposite to the direction of the voltage of the DC power supply A full bridge circuit consisting of a series circuit;
A series circuit of a first inductor and a first capacitor connected between a connection point of the switching element of one of the series circuits and a connection point of the switching element of the other series circuit;
A high side driver for driving each switching element having one end connected to the output terminal on the high voltage side of the DC power supply in the full bridge circuit;
A controller that drives each switching element of the full bridge circuit on or off directly or via the high-side driver,
A high-pressure discharge lamp lighting device in which a load circuit including a high-pressure discharge lamp is connected in parallel to the first capacitor,
The control unit maintains each of the switching elements in one set out of a set of switching elements diagonally located in the full bridge circuit at least during a period when the high-pressure discharge lamp is lit. In this state, the operation of driving each switching element of the other set on and off is repeated while periodically changing the set of switching elements to be kept off at a predetermined inversion period, and the set of switching elements to be kept off is also changed. When changing, a dead time for maintaining all the switching elements of the full bridge circuit in an off state is provided,
The high-side driver is configured to control the control unit during a period in which a voltage to ground at the other end of the switching element having one end connected to the output terminal on the high voltage side of the DC power supply is less than a predetermined drive lower limit voltage in the full bridge circuit. Regardless of the input from, the switching element cannot be driven,
The control unit sets the timing for ending the dead time when the lower one of the voltages to ground at the other end of the switching element whose one end is connected to the output terminal on the high voltage side of the DC power supply in the full bridge circuit is the drive. A high pressure discharge lamp lighting device characterized by having a timing before a timing at which the voltage becomes less than the lower limit voltage.   2. The high pressure discharge lamp lighting device according to claim 1, wherein the control unit sets a timing at which the dead time is ended to a timing before a timing at which a current flowing through the first inductor becomes zero.   The control unit monitors a current flowing through the first inductor during a dead time, and terminates the dead time when an absolute value of the current falls below a predetermined switching threshold. The high pressure discharge lamp lighting device according to 2.   The control unit monitors the voltage at the connection point between the switching element of the full bridge circuit and the first capacitor during the dead time, and terminates the dead time when a change in the voltage is detected. The high pressure discharge lamp lighting device according to claim 1, wherein:   The controller monitors the voltage at the connection point between the switching element of the full bridge circuit and the first inductor during the dead time, and terminates the dead time when a change in the voltage is detected. The high pressure discharge lamp lighting device according to claim 1, wherein:   6. The control unit according to claim 3, wherein the control unit counts the duration of the dead time and ends the dead time when the duration of the dead time reaches a predetermined upper limit time. The high pressure discharge lamp lighting device according to claim 1. Voltage detecting means for detecting a voltage across the high-pressure discharge lamp;
Current detecting means for detecting a current flowing through the first inductor;
The control unit detects the absolute value of the voltage across the high-pressure discharge lamp and the absolute value of the current flowing through the first inductor at the start of the dead time, and detects the duration of the dead time at the start of the dead time. The product of the absolute value of the current flowing through the first inductor and the inductance of the first inductor, the absolute value of the voltage across the high-pressure discharge lamp detected at the start of the dead time, and the output of the DC power supply 3. The high pressure discharge lamp lighting device according to claim 2, wherein the time is equal to or less than the time obtained by dividing by the sum of the voltage.   An illumination fixture comprising: the high-pressure discharge lamp lighting device according to any one of claims 1 to 7; and a fixture main body that holds the high-pressure discharge lamp lighting device.

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