JPH0330292A - Inverter device - Google Patents

Abstract

PURPOSE:To drive easily a load such as a high pressure discharge lamp which needs the high voltage at the time of starting by applying the high pressure pulse voltage, the high frequency voltage having a small amplitude and the direct current voltage. CONSTITUTION:The high pressure pulse voltage VOP is generated by an igniter IG during an operating period T1a, T2b, and it is applied to the high pressure discharge lamp H to make the high pressure discharge lamp H under the glow discharge condition. Next, transistors Q1, Q2 are mutually turned on/off during the operating period T2a, T2b to generate the high frequency voltage VHF, and it is applied to the high pressure discharge lamp H. The amplitude of this high frequency voltage VHF is smaller than the amplitude of the high pressure pulse voltage VOP, but it is larger than the amplitude of the direct current voltage VDC following thereafter. Next, during the operating period T3a, the positive direct current voltage VDC is generated by turning on/off the transistor Q1 with the high frequency under the condition that the transistor Q2 is turned off, and it is applied to the high pressure discharge lamp H. A load such as a high pressure discharge lamp which needs the high voltage at the time of starting is thereby driven easily.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an inverter device using semiconductor switching elements, and is particularly suitable for, for example, starting and lighting a high-pressure discharge lamp. [Prior art] Figure 7 shows a conventional inverter device (Japanese Patent Laid-Open No. 62-2679
(See Publication No. 1). Below, we will explain the circuit ellipse. The DC power supply E includes transistors Q,...
Q. series circuit and transistor Q, . Q. series circuits are connected in parallel.

The transistors Q, -44 are connected to J transistors Q, . Q
．． and the connection point of transistor Q. , Q4 are connected to a high pressure discharge lamp H via an inductor and a secondary winding of a pulse transformer PT. A capacitor C is connected in parallel to a series circuit between the secondary winding of the pulse transformer PT and the high pressure discharge lamp H, and an igniter IG is connected in parallel. Control signals from the control circuit S are supplied to the control electrodes of the transistors Q, -Q4 via drive circuits K1 -K. In the above circuit, transistor Q. Q3 is high frequency switched and transistors Q2. Q4 is switched at low frequency. FIG. 8 shows the waveform of the voltage v2 across the high-pressure discharge lamp H in the above circuit at the time of starting. During the operation period Ta in which the voltage ■2 is positive, the transistor Q4 is turned on, and the transistors Q2. Transistor Q is turned on and off at high frequency while Q is kept off. In addition, during the operation period Tb in which the voltage ■2 is negative, the transistor Q2 is turned on, and the transistor Q2 is turned on.
,,Q. Turn transistor Q3 on and off at high frequency while keeping it off. In each operating period Ta, Tb, the high voltage pulse voltage Vop generated by the igniter IQ is transmitted to the high pressure discharge lamp H via the pulse transformer PT.
is applied to. As a result, the high-pressure discharge lamp H enters a glow discharge state. The high-pressure discharge lamp H shifts from the glow discharge state to the arc discharge state due to the energy of the DC voltage VOC following the high-pressure pulse voltage Vop. In order to transition to this arc discharge state, the DC voltage VOC needs to be about 2 to 3 times the tube voltage V1a during lighting. [Problem to be solved by the invention] Since the above circuit has a full bridge structure, the high pressure discharge lamp H
The DC voltage VDC applied to is approximately equal to the voltage V1 of the DC power supply E. Therefore, if the tube voltage V1a when the high-pressure discharge lamp H is turned on is high, the voltage v1 of the DC power supply E must be increased. Since the DC power source E is obtained by rectifying and smoothing a commercial AC power source, it is usually about 140V, and even when voltage doubler is rectified, it is about 280V. Therefore, if a higher voltage is required, it is necessary to step up the voltage (1) of the DC power supply E using a step-up chopper circuit or the like, which poses a problem of increasing the size of the power supply circuit. In addition, the DC power supply E
When the voltage V of the inductor L is increased, the voltage share of the inductor L during steady lighting increases, the loss increases, the efficiency decreases, and the inductor L. The problem is that the size of the The present invention has been made in view of these points, and its purpose is to provide a compact and highly efficient device suitable for driving loads that require high voltage at startup, such as high-pressure discharge lamps. Our purpose is to provide inverter equipment. [Means for Solving the Problems] In the present invention, in order to solve the above problems, the first
As shown in the figure and Figure 2, a capacitor CI is connected in parallel to the DC power supply E and the load (high pressure discharge lamp H), and an inductor L
1 connected in series, and switching elements (transistors Q, Q2) that switch the DC power supply E and supply power to the load circuit.
The control circuit S includes a control circuit S that periodically generates a high frequency voltage vHF having a smaller amplitude than the high frequency voltage VHF and a DC voltage VOC having a smaller amplitude than the high frequency voltage VHF when the load circuit is not loaded. is generated by the DC power supply E, the load circuit, and the switching element, and the high frequency voltage VHF is at least the high voltage pulse voltage V
This is characterized in that it is generated after the application of op. Note that the high frequency voltage VHF is at least the high voltage pulse voltage V
It only needs to be generated after the application of the high voltage pulse voltage Vop
It does not matter if the high frequency voltage VHF is generated before the application of VHF. [Function] In the present invention, as described above, the high voltage pulse voltage Vop
After the application of the high-frequency voltage VHF, which has a smaller amplitude than the high-voltage pulse voltage Vop and a larger amplitude than the DC voltage VOC.
, even if the amplitude of the DC voltage VOC is small, the high-pressure discharge lamp H that has entered the glow discharge state due to the high-voltage pulse voltage Vop can be transferred to the arc discharge state using the energy of the high-frequency voltage VHF. Starting performance can be improved even if the DC voltage VDC is low.
Furthermore, since the DC voltage VDC can be lowered, the voltage share of the inductor L+ during steady state can be reduced, and loss can be reduced and the size of the inductor L can be reduced. [Embodiment 1] FIG. 1 is a circuit diagram of a first embodiment of the present invention.

The circuit configuration will be explained below. The DC power supply E includes transistors Q, . Series circuit of Q2 and capacitor C
．． ,C. series circuits are connected in parallel. Each transistor Q. ．． Diodes D, D2 are connected in antiparallel to Q2. Each capacitor C,,
C. is charged with approximately half the voltage of DC power supply E.
Connection point of transistors Q,,Q2 and capacitor Cy
, C4, a high pressure discharge lamp H is connected via an inductor L1 and a secondary winding of a pulse transformer PT. A capacitor CI is connected in parallel to a series circuit between the secondary winding of the pulse transformer PT and the high pressure discharge lamp H, and an igniter IG is connected in parallel. The control electrodes of each transistor QI, Q2 are connected to drive circuits K, , K
．． A control signal from the control circuit S is supplied via the control circuit S. Figure 2 shows the voltage waveform at the time of starting the high pressure discharge lamp H in the above circuit. Operating period T. a, T + b
Then, a high-voltage pulse voltage Vop is generated by the igniter IG and applied to the high-pressure discharge lamp H. As a result, the high pressure discharge lamp H enters a glow discharge state. Next, the operating period Tz
In a and Tzb, the transistors QI and Q2 alternately turn on and off to generate a high frequency voltage VHF, which is applied to the high pressure discharge lamp H. This high frequency voltage V
The amplitude of HF is smaller than the amplitude of the high voltage pulse voltage Vop, but larger than the amplitude of the DC voltage VOC that follows. The energy of this high frequency voltage VHF causes the high pressure discharge lamp H to transition from a glow discharge state to an arc discharge state.

Next, in the operation period 73a, the transistor Q is turned on and off at high frequency while the transistor Q2 is off, so that a positive DC voltage VDC is generated and applied to the high pressure discharge lamp H. In addition, the operating period T. In b, while the transistor Q1 is off, the transistor (h) is turned on and off at high frequency, so that a negative DC voltage is generated and applied to the high-pressure discharge lamp H. Here, in the operating periods T2a and T2b, The circuit operation when the high frequency voltage VHF is generated will be explained in detail.During this period, the transistors Q and Q2 are alternately turned on and off after a predetermined dead-off time.
First, when transistor Q, is on and transistor Q2 is off, from capacitor C, transistor Q, .
Current flows through inductor L, capacitor C, and capacitor C is discharged, and at the same time, current flows from DC power supply E through transistor Q1, inductor L, capacitor CI, and capacitor C4, and capacitor C is discharged. It will be charged. Since the high-pressure discharge lamp H is in a no-load state, almost no current flows. After that, transistor Q. ．． Q2
When both are turned off, the inductor C. Current flows through capacitor C4 and diode D2. Next, when transistor Q1 is off and transistor Q2 is on, current flows from capacitor C4 through capacitor CI, inductor L, and transistor Q2.
, is discharged, and the capacitor C,
, capacitor CI. Inductor L, transistor Q2
Current flows through the capacitor C, charging it. Then transistors Q, . When Q and Q are both turned off, the energy stored in inductor L1 causes the inductor to become inductor, and current flows through diode D1, capacitor C, and capacitor C1. Thereafter, the above process is repeated and the inductor L. A high-frequency current flows through the series resonant circuit of capacitor C and capacitor C. The frequency of this high frequency current is determined by the frequency of the transistors Q, ,Q. It is determined by the switching frequency of
Therefore, if the switching frequency is set by the control circuit S to a frequency close to the resonant frequency of the series resonant circuit (usually a frequency slightly higher than the resonant frequency), the capacitor C
A high frequency high voltage is generated at both ends of 1 due to resonance,
The voltage is applied to the high pressure discharge lamp H. The amplitude of this high frequency voltage VHF is determined by the inductor L. and the resonant frequency of the series resonant circuit consisting of capacitor C1 and transistors Q, . Since it can be set freely depending on the relationship with the switching frequency of Q2, the inductor L can be set according to the high pressure discharge lamp H used.
, the circuit constants of the capacitor C1, and the design values of the switching frequency, it is possible to obtain the desired starting performance.

Next, during the operation period T3a, the positive polarity DC voltage VO
We will explain the circuit operation when C occurs. During this period, transistor Q2 remains off, and only transistor Q1 performs on/off operations at high frequency. First, when transistor Q1 is on, capacitor C
, to transistor Q, and inductor L. Capacitor C
1, a current flows through the capacitor C, and the capacitor C is discharged. At the same time, the current flows from the DC power supply E to the transistor Q1 and the inductor L.
Current flows through capacitors C and C4 to charge capacitors C and C4. Since the high-pressure discharge lamp H is in a no-load state, almost no current flows. Next, when transistor Q1 turns off, the energy stored in inductor L causes inductor L. A current flows from the capacitor C1, capacitor C, and diode D2. Thereafter, the above process is repeated to construct a chopper circuit in which the inductor L is used as an energy storage element, the capacitor C1 is used as a smoothing element, and the diode D2 is used as a return current path, and the capacitor C1 is charged with DC voltage. Next, during the operation period T, b, the negative polarity DC voltage VO
We will explain the circuit operation when C occurs. During this period, transistor Q1 remains off, and only transistor Q2 performs on/off operations at high frequency. First, when transistor Q2 is on, capacitor C
, to capacitor C1, inductor L. , a current flows through transistor Q2 to discharge capacitor C4, and at the same time, a current flows from DC power supply E to capacitor C, , capacitor C
Current flows through inductor L, transistor Q2, and capacitor C3 is charged. Next, transistor Q
2 is turned off, the stored energy in inductor L1 causes the flow from inductor L1 to diode D+ and capacitor C.
, , a current flows through the capacitor C1. Hereinafter, the above process is repeated, the inductor LI is used as the energy storage element, the capacitor C1 is used as the smoothing element, and the diode D
The chopper circuit with , as the feedback current path is given as the III precept,
The capacitor CI is charged with a DC voltage of opposite polarity to the operating period T=a. In this way, by changing the control signal supplied to the transistor QQ2 by the control circuit S, the operation period T.
In a and Tab, a high frequency voltage VHF is applied to the high pressure discharge lamp H, and in operation periods T3a and T3b, a DC voltage VOC whose polarity is alternately reversed can be applied to the high pressure discharge lamp H. [Embodiment 2] FIG. 3 is a circuit diagram of a second embodiment of the present invention, and FIG. 4 is an operating waveform diagram thereof. In this embodiment, in order to generate the high-voltage pulse voltage Vop during the operation period T + a, T, b, an inductor Lt is used instead of the igniter IG and pulse transformer PT used in the embodiment of FIG. The resonance effect of the capacitor C1 is utilized. That is, in the inverter operation during the above-mentioned operation periods 72a and T2b, the switching frequency is changed to the inductor L.
1 and the resonant frequency of capacitor C1, a high frequency and high voltage is generated across capacitor C. In this case, the switching frequencies in the operating periods Tla and Tlb are the same as those in the operating periods T2a and T2b.
Compared to the switching frequency of the inductor L,
is set closer to the resonant frequency of capacitor C.
Therefore, the operating period T. a, T. The amplitude of the high-pressure pulse voltage Vop applied to the high-pressure discharge lamp H at time b is the same as the amplitude of the high-pressure pulse voltage Vop applied to the high-pressure discharge lamp H during the operation periods 72a and T2b.
The amplitude can be made larger than the amplitude of the high frequency voltage VHF applied to the In this embodiment, since the igniter IG and pulse transformer PT are not required, the device can be made smaller and lighter. However, the control circuit S operates during the operating period T1a, Tu
It requires a function to switch the switching frequency at T2a, T2b, and T2a.

[Example 3] FIG. 5 is a circuit diagram of a third embodiment of the present invention.

In this embodiment, an LC resonant circuit is connected in place of the igniter IG in the circuit shown in FIG. Transistor Q. ．． One end of the capacitor C2 is connected to the connection point of Q2, one end of the inductor L2 is connected to the connection point of the capacitor C3C, and a capacitor C2 is connected between the other end of the capacitor C2 and the other end of the inductor L2. , is connected. The primary winding of a pulse transformer PT is connected to both ends of the capacitor C5. capacitor C,
and inductor L2 constitute a series resonant circuit, and due to their resonance, the voltage generated across capacitor C5 is transmitted to discharge lamp H via pulse transformer PT and capacitor C.
is applied to. [Embodiment 4] FIG. 6 is a circuit diagram of a fourth embodiment of the present invention.

In this embodiment, in the conventional example shown in FIG. 7, the igniter IG
The configuration is such that the pulse transformer PT is omitted. The operating waveforms of this embodiment are the same as those shown in FIG. First, during the operating periods T + a, T + b, T2a, T2b, the transistors Q,, Q. is on and transistor Q2,
A first state in which Q, is off, and transistors Q to Q,
a second state in which all are off, and transistors Q,,Q
．． By repeating in the same order a third state in which is off and transistors Q2 and Q- are on, and a fourth state in which all transistors Q1 to Q are off, a high-frequency voltage is applied to the high-pressure discharge lamp H. applied. Operating period T + a
, T+b, the switching frequency is set closer to the resonant frequency than in the operating periods 72a and T2b, and the high-frequency pulse voltage V generated during the operating periods T, a, T+b''C'
op is the high frequency voltage V generated during the operating periods T2a and T2b
The amplitude is larger than that of HF. Next, during the operation period T3a, transistors Q2 and Q remain off and transistor Q. ．． Q. turns on and off with high frequency, high pressure discharge lamp H
DC voltage is applied to.

Furthermore, during the operation period Tsb, the transistors Q, ,Q. remains off, transistors Q 2 and Q- are turned on and off at high frequency, and a DC voltage of opposite polarity to the operating period 73a is applied to the high-pressure discharge lamp H. In addition, since Examples 1 to 3 have a half-bridge configuration, the amplitude of the DC voltage VDC is approximately half of the voltage V of the DC power supply E, but since the present example has a full-bridge configuration, the DC voltage VDC The amplitude of is almost the same as the voltage ■1 of the DC power supply E. Therefore, this embodiment is particularly suitable when the tube voltage V&a during lighting of the high-pressure discharge lamp H is high. [Effects of the Invention] According to the present invention, in an inverter device in which power is supplied by switching a DC power source using a switching element to a load circuit in which a capacitor is connected in parallel to a load and an inductor is connected in series, a high-voltage pulse voltage, a high-frequency voltage whose amplitude is smaller than this high-voltage pulse voltage, and a DC voltage whose amplitude is smaller than this high-frequency voltage are periodically generated when the load circuit is not loaded, and the high-frequency voltage is generated at least after the application of the high-voltage pulse voltage. I made it to occur, so
The high-frequency voltage that follows the high-voltage pulse voltage can provide sufficient starting voltage to the load, lowering the DC voltage and making the power supply more compact. Since the burden can be reduced, loss in the inductor can be reduced, efficiency can be improved, and the inductor can be made smaller. Furthermore, since at least the high frequency voltage and the DC voltage are generated by the DC power supply, the load circuit, and the switching element, there is an effect that the configuration of the device can be simplified.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a first embodiment of the present invention, FIG. 2 is an operating waveform diagram of the same as above, FIG. 3 is a circuit diagram of a second embodiment of the present invention, and FIG. 4 is an operating waveform diagram of the same as above. FIG. 5 is a circuit diagram of a third embodiment of the present invention, FIG. 6 is a circuit diagram of a fourth embodiment of the present invention, and FIG.
The figure is a circuit diagram of a conventional example, and Figure 8 is an operating waveform diagram of the same. E is a DC power supply, H is a high pressure discharge lamp, C is a capacitor, L
1 is an inductor, Q, Q2 are transistors, and S is a control circuit.

Claims (1)

[Claims] (1) In an inverter device comprising a DC power supply, a load circuit in which a capacitor is connected in parallel to the load and an inductor is connected in series, and a switching element that switches the DC power supply and supplies power to the load circuit, a high-voltage pulse voltage,
A high frequency voltage whose amplitude is smaller than this high voltage pulse voltage,
A control means is provided to periodically generate a DC voltage having a smaller amplitude than the high frequency voltage when the load circuit is not loaded, and at least the high frequency voltage and the DC voltage are generated by the DC power supply, the load circuit, and the switching element, and the high frequency voltage is generated after application of at least a high-voltage pulse voltage.