JPH06351259A - Power supply - Google Patents

Abstract

PURPOSE:To block steep current flow upon polarity inversion of current at an inverter section. CONSTITUTION:The voltage from a DC power supply VS is converted into a DC voltage at a flyback type converter section 1. DC power thus converted is then inverted into AC power at an inverter section 2. The voltage across a capacitor C1 connected with the output of the inverter section 2 is fed, as a power supply voltage, to a load circuit 3. The inverter section 2 is provided with an impedance element Z for discharging the capacitor C1 through switching elements Q1, Q3 at the time of polarity inversion. Charges in the capacitor C1 are decreased by means of the impedance element Z at the time of polarity inversion thus suppressing the overcurrent flowing into the converter section 1 and the inverter section 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention performs voltage conversion of a DC power supply in a converter section, converts DC power supplied from the converter section into AC power in an inverter section, and connects the output of the inverter section to a capacitor. The present invention relates to a power supply device that supplies a voltage across both ends of a power supply to a load circuit.

[0002]

2. Description of the Related Art As a power supply device, there is one that converts power supplied from a DC power supply into power necessary for a load circuit and supplies the converted power. FIG. 25 shows a conventional power supply device of this type. In this power supply device, the flyback type converter unit 1 converts the voltage of the DC power supply V _S into a DC voltage, and the inverter unit 2 converts the DC power obtained by the voltage conversion into AC power. The voltage across the capacitor C ₁ connected to the output of 2 is supplied to the load circuit 3 as a power source.

[0003] In the converter section 1, the DC power source V _S 1 winding L ₁ and the switching element Q of the transformer T ₁ at both ends of the ₀
And a series circuit is connected to turn on the switching element Q ₀ ,
The electric power induced in the secondary winding L ₂ of the transformer T _{1 when} turned off is supplied to the inverter unit 2 via the rectifying diode D ₁ . Since the converter section 1 is a flyback type, the secondary winding is Yes and wound in opposite polarity to the primary winding L ₁ of the transformer T _1, transformer T ₁ to when the switching element Q ₀ By the energy stored in the switching element Q ₀ , the voltage induced in the secondary winding L ₂ is applied to the inverter section 2 when the switching element Q ₀ is turned off.

The inverter section 2 is of a so-called full bridge construction, and a switching element Q is provided at both ends of a series circuit of a secondary winding L ₂ of a transformer T ₁ and a rectifying diode D _1.
A series circuit of ₁ , Q ₂ and switching elements Q ₃ , Q ₄ is connected in parallel, and a capacitor C ₁ is connected between the connection points of the switching elements Q ₁ , Q ₂ and the switching elements Q ₃ , Q ₄ , respectively. A load circuit 3 is connected in parallel to both ends of C ₁ .

In this inverter section 2, the switching elements Q ₁ and Q ₄ and the switching element Q at diagonal positions in the figure are shown.
₂ and Q ₃ are set as a set, and each set is turned on and off alternately. When switching elements Q ₁ and Q ₄ are turned on and switching element Q is turned on.
In a _2, Q ₃ When ON, flow in different directions of the current in the capacitor C _1, it is then supplied as a power supply voltage across the capacitor C ₁ to the load circuit 3.

In the case of the above power supply device, the switching element Q
Switching control of the switching element Q ₀ is performed at a switching frequency higher than the switching frequencies of _{1 to} Q ₄ . That is, the switching element Q ₀ is operated at high frequency, and the switching elements Q _{1 to} Q ₄ are operated at low frequency. Then, the power supplied to the inverter unit 2 is adjusted by performing PWM control or frequency control of the switching element Q _0, and the power supplied to the load circuit 3 is adjusted to a desired value.

Since the operation of this power supply device is almost the same as that of the embodiment (embodiment 1) of the present invention, detailed description of the operation is omitted. FIG. 26 shows another power supply device which converts DC power into AC power and supplies the AC power to the load circuit. This power supply device is disclosed in Japanese Patent Laid-Open No. 4-281369, and a switching element Q is provided at both ends of a DC power supply V _S.
The inductance elements L ₁ and L ₂ are connected via _0, and the switching elements Q ₁ and Q ₂ are connected to both ends of the series circuit of the inductances L ₁ and L ₂ via diodes D ₁ and D ₂ , respectively. A parallel circuit of a capacitor C ₁ and a discharge lamp LP as a load is connected between a connection point of ₁ and L _{2 and} a connection point of switching elements Q ₁ and Q ₂ .
In the above power supply device, the inductance elements L ₁ and L
₂ is a choke coil having an intermediate tap.

This power supply device includes a switching element Q ₁ ,
Q ₂ is turned on and off at a low frequency, and switching element Q ₀
Is turned on and off at high frequency. Now, when the switching element Q ₀ is turned on while the switching element Q ₁ is on, a current flows in the path of the DC power supply V _S , the switching element Q ₀ , the inductance elements L ₁ and L ₂ , and the DC power supply V _S. Thereafter, when the switching element Q ₀ is turned off, the energy stored in the inductance element L _1, the inductance element L _1, capacitor C _1, the switching element Q _1, a diode D _1, a current flows through a path of the inductance element L _1. This operation is repeated during the ON period of the switching element Q ₁ .

On the other hand, when the switching frequency Q ₂ is on, the energy stored in the inductance L ₂ when the switching element Q ₀ is on, and when the switching element Q ₀ is off, the inductance L ₂ , the diode D ₂ and the switching element Q are on. ₂ , in the path of the capacitor C ₁ and the inductance element L ₂ , the operation in which a current in the opposite direction to that when the switching element Q ₁ is turned on is repeated. As a result, a rectangular wave voltage is generated at both ends due to the smoothing action of the capacitor C ₁ , and this rectangular wave voltage is supplied to the discharge lamp LP as a power source.

[0010]

As the switching element Q ₀ of the converter unit 1 of the power supply device shown in FIG. 25, FE is used.
T is used, and the FET has a parasitic diode connected in antiparallel. In the FET used as the switching element Q ₀ , the primary winding L of the transformer T ₁ is
_When a counter electromotive voltage is induced in ₁ , a regenerative current is caused to flow to the DC power supply V _S via the parasitic diode, so that the breakdown due to the reverse voltage application is prevented. Here, the switching element Q ₀ is a transistor or an IGBT (insulate).
d-gate bipolar transistor, also known as bipolar MOS
Other switching elements such as (also called FET) may be used, but in this case as well, a diode is connected in antiparallel with the switching element in order to prevent destruction due to application of a reverse voltage.

Now, in the inverter unit 2, the switching elements Q ₃ , Q ₂ are switched from the ON state to the switching elements Q ₁ , Q 2.
Consider the time when ₄ turns on. When the switching elements Q ₃ and Q ₂ are turned on, the capacitor C ₁ is charged with the polarity shown in the figure. In this state, the switching element Q _1, Q ₄ is turned on, the power accumulated charge of the capacitor C _1, the capacitor C _1, the switching element Q _4, 2 winding L ₂ of the transformer T _1, diode D ₁ ,
A current flows through the path indicated by B in the figure of the transistor Q ₁ and the capacitor C ₁ . Also, at this time, the transformer T ₁ 2
The voltage due to the current flowing through the next winding L ₂ is ₁ of the transformer T ₁ .
Induced in the primary winding L _1, 1 winding L _1, the DC power source V _S,
A current flows through the above-mentioned parasitic diode of the switching element Q _{0 and} the path of the primary winding L ₁ indicated by B in the figure.

Since there are almost no impedance elements, which are current limiting elements, in the paths a and b, the current becomes excessive and steep. This current flows each time the current polarity of the inverter unit 2 is reversed. Here, the current value is determined by the relationship between the voltage across the capacitor C ₁ when the current polarity of the inverter unit 2 is inverted and the voltage of the DC power supply V _S. Therefore, the switching elements Q ₀ to
A large current capacity is required for Q ₄ , which tends to increase the size and cost. There is also a problem that noise is generated by the steep current.

In the case of the above power supply device, the case where the flyback type converter unit 1 is used has been described. However, a forward type or chopper type may be used, and such a forward type or chopper may be used. Even when the converter unit 1 of the type is used, when the output polarity of the inverter unit 2 is inverted (hereinafter, this state is referred to as polarity inversion), the switching elements Q _{0 to} Q are almost similar to the above case. Excessive current flows through ₄ .

Also in the case of the power supply device of FIG. 26, the charge of the capacitor C ₁ at the time of polarity reversal causes
As in the case of the power supply device of No. 5, the switching elements Q ₀ to
An excessive current flows in Q ₂ . For example, when the switching element Q ₂ is switched from the on state to the switching element Q ₁ on state, the capacitor C ₁ is charged to the polarity shown in FIG. 26, and the switching element Q ₁ is turned on by the charge. At times, an excessive current flows through the paths indicated by arrows a and b in the figure.

The present invention has been made in view of the above points, and an object thereof is to provide a power supply device capable of preventing a steep current from flowing when the current polarity of the inverter section is reversed. To do.

[0016]

According to the invention of claim 1, in order to achieve the above object, a DC power supply, a converter section for converting the voltage of the DC power supply, and a DC power supplied from the converter section are AC power. To the inverter, the capacitor connected to the output of the inverter, the load circuit connected in parallel with this capacitor to supply the voltage across the capacitor as a power source, and the charge charged in the capacitor when the polarity of the inverter is reversed. And an impedance element that reduces the charge, and a loop forming unit that forms a loop that discharges the charge charged in the capacitor between the capacitor and the impedance element when the polarity is inverted.

According to a second aspect of the present invention, the loop forming means controls the switching of the switching element of the inverter section so as to form a path for discharging the charge stored in the capacitor through the impedance element when the polarity is inverted. It can be configured by means. More specifically, as described in claim 3, as the inverter section, a switching element configured by bridge connection is used, and the capacitor and the load circuit are connected between connection points of the switching elements connected in series. Impedance element that connects the parallel circuit of, and inserts a rectifying element in series with each switching element connected in series, and reduces the charge charged in the capacitor during polarity reversal between the connection points of each rectifying element and switching element. Should be connected.

FET having a slow recovery time of a parasitic diode as a switching element which constitutes the inverter section
In order to prevent a surge voltage from being generated even when the FET is used, when the FET is used as the switching element, the parasitic diode of the switching element is bypassed and the charge of the capacitor is charged. It is preferable to provide a loop forming means for forming an inside of a loop that discharges to the impedance element.

In order to speed up the rising of the capacitor connected to the output of the inverter section when the polarity is reversed, it is preferable to use an inductance element as the impedance element as described in claim 5. When a plurality of inductance elements are used as the impedance element, it is preferable that the inductance elements are electromagnetically coupled to each other in order to reduce the size of the impedance element.

The power supply device may be, for example, as defined in claim 7.
As shown in, the load circuit can be applied when it is a series circuit of a discharge lamp and an inductance element. Further, as described in claim 8, it is also possible that the switching control means performs switching control of the switching element so that the output voltage waveform becomes a substantially rectangular wave and supplies the rectangular wave power to the load circuit.

As the converter section, a section provided with a transformer for insulating and separating the DC power source and the inverter section from each other may be used. In the power supply device of claim 9, as in claim 10, the secondary winding of the transformer is also used as an impedance element for reducing the charge charged in the capacitor at the time of polarity reversal, and is connected to the primary side of the transformer. A current limiting unit for limiting the regenerative current to the DC power supply or a blocking unit for blocking the current may be provided.

Further, in the power supply device according to claim 9, when suppressing the regenerative current flowing at least on the secondary side of the transformer, as shown in claim 11, the secondary side of the transformer is provided at the time of polarity reversal. It suffices to insert a current limiting element in the regenerative current loop due to the charge charged in the capacitor. In order to remove the influence of the current limiting element during the period other than the polarity reversal period, it is preferable to provide a switching means for short-circuiting the current limiting element during the period other than the polarity reversal period.

When the power supply device of claim 11 is embodied, as shown in claim 13, the converter section includes a transformer having two secondary windings, and the secondary windings of the respective transformers are connected in series. Connect two switching elements in series at both ends of the circuit, connect a parallel circuit of a capacitor and a load circuit between the connection point of the secondary winding and the connection point of the switching element, and charge the capacitor when the polarity is reversed. The electric current due to electric charge is 2
You may make it provide with the loop formation means which forms a loop which bypasses the following winding and discharge | releases, and the current limiting element which limits the loop current.

According to the fourteenth aspect, the converter section may be configured by using a plurality of sets of converters.

[0025]

According to the first aspect of the present invention, as described above, the impedance element for reducing the electric charge charged in the capacitor when the polarity of the inverter is inverted, and the charged electric charge of the capacitor is discharged between the capacitor and the impedance element when the polarity is inverted. And a loop forming means for forming a loop to reduce the charge charge of the capacitor at the time of polarity reversal by the impedance element, reduce the current flowing through the inverter unit and the converter unit using this charge charge as a power source, Prevents overcurrent from flowing during reversal.

According to a second aspect of the invention, the switching control means controls the switching of the switching element of the inverter so that the loop forming means forms a path for discharging the charge charged in the capacitor through the impedance element at the time of polarity reversal. With this configuration, the switching element of the inverter section is also used as the loop forming means to simplify the circuit configuration.

According to the invention of claim 4, when the FET is used as the switching element, a loop forming means is provided for bypassing the parasitic diode of the switching element and forming a loop for discharging the charge charged in the capacitor to the impedance element. As a result, when a FET having a slow recovery time of a parasitic diode is used as a switching element that constitutes the inverter unit, the charge stored in the capacitor at the time of polarity reversal is not discharged through the parasitic diode, and the surge voltage is generated when the parasitic diode is turned off. To prevent the occurrence of.

According to the fifth aspect of the present invention, by using the inductance element as the impedance element, the inductance element releases the energy due to the charging charge released from the capacitor to the capacitor, and after the polarity is reversed, the capacitor is rapidly charged to the opposite polarity. However, the rising speed at the time of polarity reversal of the capacitor connected to the output of the inverter unit is accelerated.

As described in claim 6, by using the inductance element as the impedance element and electromagnetically coupling the inductance elements to each other, the inductance element can be integrally wound around the coil bobbin to form a small impedance element. To do. According to a tenth aspect of the present invention, as in the power supply apparatus according to the ninth aspect, the converter section is provided with a transformer that insulates and separates the DC power source from the inverter section. Also serves as an impedance element to reduce the electric charge charged in the transformer, suppresses the regenerative current on the secondary side of the transformer by the inductance component of the secondary winding, and limits the regenerative current to the DC power source on the primary side of the transformer. A current limiting means or a blocking means for blocking is provided, and the regenerative current is suppressed or blocked by the charge of the capacitor on the primary side of the transformer.

According to the invention of claim 11, in the power supply device of claim 9, by inserting a current limiting element in the secondary side of the transformer in the regenerative current loop due to the charge charged in the capacitor at the time of polarity reversal, The regenerative current is suppressed by the charge of the capacitor on the secondary side. According to the twelfth aspect of the invention, the influence of the current limiting element is removed during the period other than the polarity reversal period by providing the switching means for short-circuiting the current limiting element during the period other than the polarity reversal period.

[0031]

(Embodiment 1) FIG. 1 shows an embodiment of the present invention. In the power supply device of this embodiment, basically, the voltage of the DC power supply V _S is converted into a predetermined voltage by the flyback type converter unit 1 and the voltage is converted in the same manner as described in the section of the prior art. The DC power is converted into AC power by the inverter unit 2 having a full bridge structure. The characteristic feature of the present embodiment is that the switching elements Q ₁ connected in series in the inverter unit 2 having a full-bridge structure,
The rectifying diode D of the converter unit 1 is connected in series to the series circuit of Q _{2 and} the series circuit of the switching elements Q ₃ and Q _4.
1 and D ₂ are respectively connected in series, and the diode D ₁ ,
An impedance element Z is connected between the cathodes of D ₂ . Although the rectifying diodes D ₁ and D ₂ are components of the converter unit 1, they are incorporated in the inverter unit 2 in FIG. 1 for convenience of explanation.

The operation of the power supply device will be described with reference to FIG. The switching elements Q _{1 to} Q ₄ of the inverter unit 2 are
As shown in FIGS. 2B to 2E, the switching element Q ₀ of the converter unit 1 is turned on and off at a low frequency, and the switching element Q ₀ of the inverter unit 2 is switched to the switching element Q ₀ of the inverter unit 2 as shown in FIG. _{While 1} , ₁ and Q ₄ or switching elements Q ₂ and Q ₃ are on, they are turned on and off at high frequency.

Now, the switching element Q₁, Q_FourIs off
And the switching element Q₂, Q ₃Is on
t₂-T₃During the period of, switching element Q₀On period of
In between, switching element Q₀Shown in FIG. 2 (f) through
Current i₁Flows and this current i ₁By T₁To
Nergi accumulates. And the switching element Q₀of
Transformer T when off₁Secondary winding L₂Induced voltage
(Voltage with high voltage in black circle direction) Secondary winding L₂, Da
Iodo D₂, Switching element Q₃, Capacitors
C₁, Switching element Q₂Secondary winding L₂In the route of
The current i shown in FIG.₂Flows. The current i₁, I
₂Is the switching element Q₀Flows intermittently every time the
Be done. The current i₂Capacitor C₁Figure on both ends of
The voltage shown in 2 (i) is generated. The capacitor C₁of
The voltage Vc between both ends is the capacitor C₁2 by the smoothing effect of
The voltage waveform has a rectangular waveform shown in (i).

At time t ₃ , the switching element Q
₂ is turned off and the switching element Q ₁ is turned on. As a result, the impedance element Z is connected in parallel to the capacitor C ₁ via the switching elements Q ₁ and Q ₃ . Here, the switching element that constitutes the inverter unit 2 of this type is also configured by connecting diodes in antiparallel. When the FET is used, the above diode is not necessary due to the parasitic diode, but the diode may be connected in anti-parallel in some cases.

[0035] At the time t _3, since the capacitor C ₁ is charged in a direction opposite to the direction shown by the arrow, as a power source to charge the charge of capacitor C _1, the capacitor C _1, the switching element Q ₃ (anti-parallel diode ), The impedance element Z, the switching element Q ₁ , and the capacitor C ₁ pass the current i ₃ . Note that at this time t ₃ , the direction of the current is opposite to the arrow in FIG.
It becomes a negative current as shown in.

[0036] Here, when the impedance element Z is an inductance element, the resonance between the capacitor C ₁ and the impedance element Z, the energy stored in the impedance element Z in charges of the capacitor C ₁ is the impedance element Z, the switching element Q ₁ , the capacitor C ₁ , the switching element Q ₃ (an antiparallel diode), and the impedance element Z are discharged to the path, and the capacitor C ₁ is charged with an opposite polarity. Therefore, the current waveform has a sine wave shape (half wave) shown in FIG.

Time t₃-T_FourIn the period of
Touching element Q_FourIs turned on at time t_FourAt the point of
Holding element Q₃Is turned off and the converter unit 1
Switching element Q₀To turn on. Where the switch
Element Q_FourInvention is solved when is turned on
As described in the section of the problem to be solved, the capacitor C
₁The charge of the₁,switch
Element Q_Four, Transformer T₁Secondary winding L₂, Daio
De D₁, Switching element Q₁, Capacitor C ₁The route
The current is about to flow through, but in the case of this embodiment,
By the action of the impedance element Z
Capacitor C₁Charge is discharged, or
Indexer C₁Is charged in the opposite polarity,
There is no flow.

Time t_FourThen, switching element Q₁, Q
_FourIs turned on, and the switching element of the converter unit 1 described above is turned on.
Child Q₀Is turned on, the time t₂-T_FourSame as explained in
Then, the current i shown in FIG.₁Flows, and this
Transformer T₁Secondary winding L₂The voltage induced in
Secondary winding L₂, Diode D₁, Switching element
Q ₁, Capacitor C₁, Switching element Q_FourSecond volume
Line L₂The current i shown in FIG.₂Flows. This
, The impedance accumulated in the impedance element Z described above is
Nergi, impedance element Z, switching element Q
₁, Capacitor C₁, Switching element Q₃(Anti-parallel data
(Iode), is emitted through the path of impedance element Z, and
Indexer C₁The effect of charging the
SA C₁The voltage across both ends rises faster.

Time t_FourSubsequent switching element Q
_FourIs turned off (time t in FIG. 2). ₁Corresponds to that point
2), as shown in Fig. 2 (i).
SA C ₁Is time t₂-T₃It is charged with the opposite polarity to the case of.
Next, the switching element Q_FourIs turned off at time t₁so
Is the switching element Q ₃Is turned on at time t₃-T_Four
As described in the period of₁Accumulated in
Electric charge is released to the impedance element Z. However, above
In the case described above, the capacitor C₁Is the polarity of the arrow
Capacitor because it is charged to generate voltage
C₁, Switching element Q₁(Anti-parallel diode), a
Impedance element Z, switching element Q₃, Conden
SA C₁In the path of, capacitor C₁In the path of the arrow in Figure 1
The current i₃Flows.

Then, time t₁-T₂In the period of
First, switching element Q₂Turn on and then switch
Element Q₁To turn off. Also at this time, the capacitor
C₁After the charge is discharged from the switching element Q
₁, Q_FourIs off, switching element Q₂, Q₃Is on
Since it becomes the state of₁, Switching element
Q₂, Transformer T₁Secondary winding L₂, Diode D₂,
Switching element Q₃, Capacitor C₁Over the path of
No current flows. The impedance element Z
The energy stored in the
Touching element Q ₃, Capacitor C₁, Switching element
Q₁(Anti-parallel diode), impedance element Z
Emitted on the road, capacitor C₁Charge with reverse polarity.

After that, by repeating the above operation,
, Capacitor C₁Is the rectangular wave voltage shown in FIG.
Is generated, and this rectangular wave voltage is supplied to the load circuit 3 as a power source.
Be paid. By the way, impedance is required in the above case.
The case where the element Z is an inductance element has been described.
However, as shown in FIGS. 3A to 3C, the resistance R or
Is a series circuit of a resistor R and an inductance element L, or 2
Transformer T with resistor R connected to the next side₂Even
Yes. However, resistor R and capacitor C₁Charged to the
When the load is consumed, when the polarity of the inverter unit 2 is reversed (switch
Touching element Q₁, Q _FourSet and switching element Q₂，
Q₃When the on and off states of the pair of
Sensor C₁Need to be charged from the beginning, which is why
Densa C₁The voltage rises at both ends becomes slower and the loss increases
To do. Therefore, the impedance element Z is
It is preferable to use a chest element.

(Embodiment 2) Load circuit 3 in Embodiment 1
Is a series circuit of a discharge lamp LP such as a metal halide lamp and an inductance element L _2, and a switching element Q
An embodiment using FETs as _{1 to} Q ₄ is shown in FIG. In addition, the inductance element L is used as the impedance element Z.
₁ is used.

From the ON state of the switching elements Q ₂ and Q ₃ of the inverter unit 2 of this embodiment, the switching elements Q ₁ and
FIG. 5 shows the switching operation at the time of polarity reversal in which Q ₄ is turned on. At time t ₁ in FIG. 5, the switching elements Q ₂ and Q ₃ that have been on until then are turned on.
Is turned off as shown in FIGS. Then, until the time t ₂ and turns off all the switching elements Q ₁ to Q _4, as shown in FIG. 5 (a) ~ (d) . This period of time t ₁ -t ₂ is what is called dead time.

At time t ₂ , the switching element Q ₁ is _first turned on as shown in FIG. Then, the charge stored in the capacitor C ₁ is a capacitor C _1, the parasitic diode D ₃ of the switching element Q _3, the inductance element L _1, the switching element Q _1, is discharged in a path of the capacitor C _1. Here, due to the resonance between the inductance element L ₁ and the capacitor C ₁ , the inductance element L ₁
Energy stored in is discharged to the capacitor C ₁ in the above path, the capacitor C ₁ is charged by it to the opposite polarity. At this time, the current shown in FIG. 5 (f) flows through the path. When the energy of the inductance element L ₁ is all discharged, the parasitic diode D ₃ of the switching element Q ₃ is turned off, the current of the path does not flow. That time is time t ₃ . At this time, the voltage Vc across the capacitor C ₁ has the opposite polarity, and has almost the same voltage value as that before the charge is discharged to the inductance element L ₁ .

Then, at time t ₄ , the switching element Q ₄
To turn on. At this time, since the capacitor C ₁ is charged with the opposite polarity, an excessive current does not flow through the switching elements Q ₁ and Q ₄ and the converter unit 1 by using the charge stored in the capacitor C ₁ as a power source. By inverting the inverter unit 2 as described above,
When the voltage V _C across the capacitor C ₁ at the time of polarity reversal rises satisfactorily and the load circuit is a discharge lamp such as a metal halide lamp, the period during which the current flowing through the discharge lamp becomes almost 0 becomes short, Or it disappears, so that problems such as extinction and difficulty in re-ignition are less likely to occur.

The inductance element L ₂ connected in series with the discharge lamp LP serves as a filter for preventing high frequency ripple components from being added to the discharge lamp LP, and the discharge lamp LP is acoustically resonant. It is provided to prevent the phenomenon from occurring and to stably turn on the discharge lamp LP. The inductance element L ₂ may also serve as the secondary winding of the pulse transformer of the starting igniter.

Switching of the switching elements Q _{1 to} Q ₄ of the inverter unit 2 so as to form a path for discharging the charge charged in the capacitor C ₁ through the impedance element Z at the time of polarity reversal in the above-described first and second embodiments. It is needless to say that the operation of controlling is performed by the switching control means included in the inverter unit 1. (Embodiment 3) FIG. 6 shows still another embodiment of the present invention.
When FETs having a slow recovery speed of the parasitic diode are used as the switching elements Q ₁ and Q ₂ of the above-described second embodiment, the parasitic diode is turned off after the energy is transferred from the inductance element L ₁ to the capacitor C ₁ at the time of polarity reversal. Surge voltage may occur. Therefore, the present embodiment improves on this point.

In the present embodiment, the diode D ₁₂ inserted between both ends of the inductance element L ₁ , the connection point of the switching element Q ₁ and the diode D ₁ , and the connection point of the switching element Q ₃ and the diode D _2. , D ₁₃ disconnects the inductance element L ₁ from the switching elements Q ₁ and Q ₃ , that is, disconnects the parasitic diode of the switching elements Q ₁ and Q ₃ , and forms a resonance path between the capacitor C ₁ and the inductance element L _1. To do this, diodes D ₁₀ and D ₁₁ are connected between both ends of the capacitor C ₁ and the inductance element L ₁ .

The switching element Q _{2 of} the inverter unit ₂ ,
At the time of polarity reversal in which the switching elements Q ₁ and Q ₄ are turned on from the on state of Q _3, the path through which the resonance current flows is the capacitor C ₁ , the diode D ₁₁ , the inductance L ₁ , the diode D ₁₂ , and the transistor. Q ₁ ,
It becomes the capacitor C ₁ . Therefore, the switching element Q
_No resonance current flows in the path through the parasitic diode of ₃ . Similarly, at the time of polarity reversal in which the switching elements Q ₁ and Q ₄ are turned on and the switching elements Q ₂ and Q ₃ are turned on, a resonance current does not flow in the path passing through the parasitic diode of the switching element Q _1. . Therefore, the FET with a slow recovery time of the parasitic diode
Is used as the switching elements Q ₁ and Q ₃ , no surge voltage is generated when the parasitic diode is turned off.

(Fourth Embodiment) FIG. 7 shows still another embodiment of the present invention. This embodiment is also the same as the third embodiment except that the second embodiment is used.
When FETs having a slow recovery speed of the parasitic diode are used as the switching elements Q ₁ and Q ₂ of, when the parasitic diode is turned off after the energy is transferred from the inductance element L ₁ to the capacitor C ₁ at the time of polarity reversal, It prevents the generation of surge voltage.

In this embodiment, a set of inverter units 2 is formed.
Switching element Q₁, Q_FourAnd switching element
Q₂, Q₃Capacitor C when turned on₁Charged to
Depending on the polarity of the voltage, the capacitor C₁Discharges the charge of
The impedance element Z is individually provided.
Specifically, the switching element Q₁, Q₂Connection point of
Diode D₂And switching element Q₃Between the connection point of
And the diode D_TenAnd inductance element L₁₁In series with
Connect the circuit, switching element Q₃, Q_FourConnection point
And diode D ₁And switching element Q₁Connection point of
Between the diode D₁₁And inductance element L₁₂With
A series circuit is connected.

In the case of this embodiment, when the switching elements Q _{1 to} Q ₄ are operated as described with reference to FIG. 5, as in the case of the third embodiment, the path through the parasitic diode of the switching element Q ₃ is changed. It is possible to prevent the surge voltage from being generated when the parasitic diode is turned off, even if FETs having no parasitic current and slow recovery time of the parasitic diode are used as the switching elements Q ₁ and Q ₃ .

By the way, the switching elements Q _{1 to} Q ₄ can be switched by a method other than that shown in FIG. The switching operation in that case will be described with reference to FIG. Note that FIG. 8 also shows the switching operation at the time of polarity reversal in which the switching elements Q ₂ and Q ₃ of the inverter unit 2 are switched from the ON state to the states in which the switching elements Q ₁ and Q ₄ are turned ON.

At time t ₁ , when the switching elements Q ₂ and Q ₃ shown in FIGS. 8C and 8D are turned on, the switching element Q ₁ is further turned on as shown in FIG. 8A. Thus, charges of the capacitor C ₁ is a capacitor C _1, diode D _11, the inductance element L _12, the switching elements Q _1, is released through a path of the capacitor C _1, the resonance behavior of the capacitor C ₁ and the inductance element L ₁₂ Is started.

Next, at time t ₂ , as shown in FIG. 8C, the switching element Q ₃ is turned off. In addition,
The time when the switching element Q ₃ is turned off is after the time when the switching element Q ₁ is turned on, and before the time when the switching element Q ₂ shown in FIG. Now, assuming that all the charges charged in the capacitor C ₁ are released to the inductance element L ₁ at time t ₃ , the energy accumulated in the inductance element L ₁₂ causes the inductance L ₁₂ , the switching element Q ₁ , the switching element Q ₂ , and the switching element to switch. The light is emitted through the path of the element Q ₄ (parasitic diode D ₄ ) and the diode D ₁₁ . At this time, the impedance of the capacitor C _1, because the energy of the inductance element L ₁₂ is not released into the capacitor C _1, after which time t ₃ is maintained at the voltage across V _C is substantially zero capacitor C _1.

At time t ₄ , the switching element Q ₄ is turned on as shown in FIG. 8 (b). However, in this case, the parasitic diode D ₄ is maintained in the ON state, and thus the emission state of the inductance element L ₁₂ is maintained at the time t ₃ thereafter. Then, at time t ₅ , the switching element Q ₂ is turned off as shown in FIG. In this case, since the switching element Q ₂ is turned off, the switching element Q ₂
The path passing through ₂ is cut off, and the energy of the inductance element L ₁₂ is released through the path of the inductance element L ₁₂ , the switching element Q ₁ , the capacitor C ₁ , the diode D ₁₁ , and the inductance element L ₁₂ . Here, at time t ₆ when the energy of the inductance element L ₁₂ is completely discharged to the capacitor C ₁ , the inversion operation of the inverter unit 2 is completed.

When the switching operation is performed as described above,
It has the following advantages: In the switching operation of FIG. 5, the path for supplying the current from the converter unit 1 to the inverter unit 2 at the dead time is not secured. However, when the operation is performed as shown in FIG. 8, when the inverter unit 2 is viewed from the converter unit 1, even when the polarity of the inverter unit 2 is reversed, a current flow path is always ensured. In this case, there is an advantage that a surge voltage is not generated even when a current is supplied from the converter unit 1 when the polarity of the inverter unit 2 is reversed.
It should be noted that such a switching operation can also be applied to the previous embodiment.

(Embodiment 5) FIG. 9 is a diagram in which the inductance elements L ₁₁ and L ₁₂ of Embodiment 4 are magnetically coupled. In this way is magnetically coupled inductance elements L _11, L _12, the inductance element L ₁₁ in the same coil bobbin, L
₁₂ can be wound, and the inductance elements L ₁₁ and L ₁₂ can be downsized. Note that the inductances L ₁₁ , L ₁₂
Are wound so as to have the same polarity in consideration of the voltage stress applied to the diodes D ₁₀ and D ₁₁ . However, if the voltage stress of the diodes D ₁₀ and D ₁₁ does not pose a problem, the inductances L ₁₁ and L ₁₂ may be wound with opposite polarities. Further, even if the inductance elements L ₁₁ and L ₁₂ of this embodiment are magnetically coupled, they can be operated in the same manner as described with reference to FIG. 5 or 8.

(Embodiment 6) In each of the embodiments described above, the impedance element Z for discharging the charge stored in the capacitor C ₁ was provided on the high potential side of the inverter unit 2 having the full bridge structure. In the embodiment, as shown in FIG. 10, the impedance element Z is provided on the low potential side of the inverter unit 2. In the case of FIG. 10, transistors are used as the switching elements Q _{1 to} Q ₄ , and the diodes D ₂₀ and D ₂₁ connected in antiparallel to the transistors Q ₂ and Q ₃ use FETs as switching elements. In this case, the inductance element L ₁ is used as the impedance element Z. As described above, even if the impedance element Z is provided on the low potential side of the inverter unit 2, the same effect as that of each of the above-described embodiments can be obtained.

(Embodiment 7) In each of the above-mentioned embodiments, the impedance element Z is individually provided, but in this embodiment, the secondary winding L ₂ of the transformer T ₁ of the converter unit 1 is connected to the capacitor C. It is also used as the impedance element Z for reducing the charged charge of ₁ . In addition, in the case of the present embodiment, the following description will be made especially for the case of being used for a lighting device mounted on a vehicle. Headlights and the like are used as the illumination device, and high-pressure discharge lamps such as metal halide lamps are used as the headlights. In such a case, in the converter unit 1, it is necessary to boost the voltage of the DC power supply V _S of several ten volts, such as a vehicle battery, to several hundred volts. A discharge lamp such as the metal halide lamp described above requires a voltage of about 300 V at the time of starting. Therefore, the current at the time of polarity reversal explained in the section of the problem to be solved by the invention becomes extremely large.

In this embodiment, as shown in FIG. 11, the secondary winding L ₂ of the transformer T ₁ of the converter section 1 is made into two windings, and both ends of the secondary winding L ₂ (L ₂₁ and L ₂₂ The switching elements Q ₁ and Q ₂ are connected in series via the diodes D ₁ and D ₂ to both ends of the series circuit, and the connection point of the secondary windings L ₂₁ and L _{22 and} the connection point of the switching elements Q ₁ and Q ₂ are connected. A capacitor C ₁ is connected between the capacitor C ₁ and, and a discharge lamp LP, which is a load, is connected to the capacitor C ₁ . Further, the converter unit 1 is adapted to be supplied with the DC power supply V _S via the diode D ₀ .

In the power supply device of this embodiment, as shown in FIG.
As shown in (b), the switching elements Q ₁ and Q ₂ of the inverter unit 2 are alternately turned on and off at low frequencies (several tens to
(Several hundreds of Hz), the switching element Q ₀ is turned on and off at high frequency as shown in FIG.
Hz). Now, at the time of the on-switching elements Q _1, on the switching element Q _0, by off, FIG. 12 (d)
The current i ₁ shown in the figure flows, and this current i ₁ causes the transformer T
_The voltage induced in the secondary winding L _{21 of 1} causes the secondary winding L ₂₁ to
_The current i ₂ shown in FIG. 12 (e) flows through the path of ₂₁ , the diode D ₁ , the switching element Q ₁ , the capacitor C ₁ , and the secondary winding L ₂₁ . Then, this current i ₂ charges the capacitor C ₁ to generate a voltage across the polarities shown in FIG.

When the switching element Q ₁ is turned off and the switching element Q ₂ is turned on, the switching element Q ₀
The voltage induced in the secondary winding L ₂₂ of the transformer T ₁ according to the on / off state of the secondary winding L ₂₂ , the secondary winding L ₂₂ , the capacitor C ₁ , the switching element Q ₂ , the diode D ₂ , and the secondary winding L. _In the route of ₂₂ , a current in the direction opposite to that when the switching element Q ₁ is turned on is passed through the capacitor C ₁ .

By repeating the above operation, the capacitor C is turned on and off according to the ON / OFF of the switching elements Q ₁ and Q _2.
A rectangular wave voltage shown in FIG. 12 (f) is generated at both ends of ₁ , and this rectangular wave voltage is applied to the discharge lamp LP,
P is lit by a so-called rectangular wave. Since the high frequency ripple component generated by the switching of the switching element Q ₀ flows through the capacitor C ₁ , almost rectangular wave voltage is applied to the discharge lamp LP. Furthermore, in order to prevent the high frequency ripple component from being applied to the discharge lamp LP,
An inductance element may be connected in series with the discharge lamp LP.

In addition, the switching elements Q ₁ ,
At the time of switching on and off of Q ₂ , both switching elements Q
A simultaneous ON period is provided in which ₁ and Q ₂ are simultaneously turned ON.
That is, the simultaneous ON period is provided in consideration of the fact that the current due to the voltage induced in the secondary windings L ₂₁ and L ₂₂ of the transformer T ₁ flows. Next, the operation at the time of polarity reversal in which the switching elements Q ₁ and Q ₂ are switched on and off will be described. Now, if switching from a state in which the switching element Q ₁ is turned on in a state where the switching element Q ₂ is turned on, just before the switching element Q ₂ is turned on, the capacitor C in a polar capacitor C ₁ is illustrated in FIG. 11 ₁ is charged. In this state, the switching element Q ₂ is turned on, as a power source to charge the charge of capacitor C _1, the capacitor C _1, the switching element Q _2, diode D _2, 2 windings L _22, capacitor C ₁
The current flows through the path. Current at this time flows via the secondary winding L _22, the peak value by the impedance of the secondary winding L ₂₂ is limited to a sufficiently low value. That is, 2
The secondary winding L ₂₂ functions as an impedance element Z.

When the switching element Q ₂ is turned on and the switching element Q ₁ is turned on, the current limiting function of the secondary winding L ₂₁ prevents the excessive current from flowing in the same manner. By the way, when a current for discharging the charge of the capacitor C ₁ flows through the secondary windings L ₂₁ and L ₂₂ ,
Accordingly, the DC power source V is applied to the primary winding L ₁ of the transformer T _1.
A voltage that causes a regenerative current to flow is induced through _S , but the current due to this voltage is blocked by the diode D ₀ . For this reason, it is possible to prevent excessive stress from being applied to the switching elements Q _{0 to} Q ₂ of the converter section 1 and the inverter section 2 due to the charge of the capacitor C ₁ .

In the above description, the blocking means for blocking the regenerative current to the DC power source V _S , such as the diode D ₀ , has been described, but the current limiting means for limiting the regenerative current is provided. Alternatively, an impedance element such as an inductance element may be provided. (Embodiment 8) By the way, when the diode D ₀ or the current limiting means is provided in the converter unit 1 as in the embodiment 7, the DC power supply V _S such as the battery of the vehicle which may be reduced to 10 V or less of the power supply voltage. In this case, the voltage drop due to the diode D ₀ and the current limiting means becomes a problem. For example, even if a Schottky diode is used as the diode D ₀ , a voltage drop of about 0.5 to 0.8 V occurs.

Therefore, this example is improved in this example, and in this example, the diode D ₀ in Example 7 is used.
Instead of M, as shown in FIG.
Using OSFETQ _6, by turning off in synchronization with the MOSFET Q ₆ in the polarity inversion period, it is to prevent the current from overflowing into the converter section 1. In the present embodiment, the inverter unit 2 has a full-bridge structure, and the function of preventing overcurrent flowing in the inverter unit 2 is basically obtained by the secondary winding L ₂ as described in the seventh embodiment. I am doing it.

In the case of this embodiment, the transformer T
_A switching element (for example, a thyristor such as a diac) Q that is turned off when the voltage induced in the tertiary winding L ₃ reaches a predetermined voltage with a predetermined polarity by providing a tertiary winding L _{3 in 1 A} bias circuit composed of ₅ and a resistor R ₁ is used to control ON / OFF of the MOSFET Q ₆ .

Operation of converter section 1 and inverter section 2
Will operate in the same way as described in the previous embodiment, so the description is omitted.
The polarity reversal of the inverter unit 2, which is a feature of this embodiment, is omitted.
The operation at that time will be described. Inverter unit 2 of this embodiment
Switching elements Q in₁, Q_FourAnd Sui
Touching element Q₂, Q₃When switching on and off,
Switching element Q ₁~ Q_FourFor a short period of time
There is a simultaneous ON period. For example, switching element
Q₂, Q₃From ON to switching element Q₁, Q_FourOh
Capacitor C when switching to₁In Figure 13
It is charged with the polarity shown. And switching
Element Q₁, Q_FourIs turned on, the capacitor C₁of
The charge C is used as a power source and the capacitor C₁, Switching
Element Q_FourSecondary winding L₂, Diode D₁, Switchon
Element Q₁, Capacitor C₁The current flows through the path. Na
This current is the secondary winding L₂Is suppressed by.

The above currents induce voltages in the primary winding L ₁ and the tertiary winding L ₃ of the transformer T ₁ , respectively. Here, as shown in FIG. 14D, the switching element Q ₅ is turned off by the voltage induced in the tertiary winding L ₃ (T in the figure).
It is turned off for a period indicated by _D ), which causes MOSFET Q ₆
The gate voltage for turning on is no longer applied to the MOSFET Q ₆ , and the MOSFET Q ₆ is turned off. Therefore, it is possible to interrupt the current regenerated in the DC power supply V _S by the voltage induced in the primary winding L ₁ by the current flowing in the secondary winding L ₂ when the polarity is reversed.

During the period except when the polarity is reversed, the switching element Q ₅ is turned on by the voltage induced in the tertiary winding L ₃ , and the MOSFET Q ₆ is turned on. MOSFET Q ₆ does not affect the operation of the above. (Embodiment 9) In the present embodiment, as shown in FIG. 15, a current limiting inductance element L ₄ is connected in series to the secondary winding L ₂ of the converter unit 1, and an inverter is connected in parallel with this inductance element L _4. A switching element Q ₇ that is turned off only when the polarity of the portion 2 is inverted is connected.

[0073] Figure 16 is a circuit diagram specifically showing the switching element Q _7, MO as a switching element Q ₇
The SFET is used and on / off of the switching element Q ₇ is controlled by the tertiary winding L ₃ provided in the transformer T ₂ . The tertiary winding L ₃ is wound in the same polarity as the primary winding L _1, and a transient surge voltage is applied to the switching element Q ₇ in the tertiary winding L _3. A surge absorbing element Q ₈ such as a blocking ZNR is connected in parallel.

In this embodiment, the switching element Q₁, Q_Four
Or switching element Q₂, Q ₃When turned on,
Touching element Q₀Transformer T when is off₁The third
Winding L₃The voltage induced in the
And the switching element Q₇Turns on. For this reason,
Inductance element L_FourAre short-circuited and the switching element
Child Q₁, Q_FourOr switching element Q₂, Q₃Oh
At the time of operation, as explained in the conventional circuit or other embodiment,
Similarly, the power supply operates.

When the polarity of the inverter section 2 is reversed, the voltage charged in the tertiary winding L ₃ by the current flowing through the secondary winding L ₂ using the charge charged in the capacitor C ₁ as a power source As shown in 17 (d), MOSFETQ
₇ is off. Therefore, the current at the time of the polarity reversal flows through the secondary winding L ₂ and the inductance element L ₄ and is suppressed to a small level.

Here, since the current flowing in the secondary winding L ₂ of the transformer T ₁ is suppressed by the charge of the capacitor C ₁ , the DC power supply V _S is generated by the voltage induced in the primary winding L _1.
The current flowing through the regeneration of the
The means for suppressing the regenerative current on the secondary side is unnecessary. (Example 10) This embodiment is an example in which the secondary side of the transformer T ₁ of the embodiment 7 shown in FIG. 11 is applied when a center tap, as shown in FIG. 18, a capacitor C ₁ Is connected in series with the parallel circuit of the inductance element L ₄ and the switching element Q ₇ described in the ninth embodiment. Since the operation of this embodiment is the same as that described in the ninth embodiment, the description is omitted.

(Embodiment 11) In the case of Embodiment 9 and Embodiment 10 shown in FIG. 15 and FIG. 16 or FIG. 18, a circuit for switching control of MOSFET Q ₇ as a switching element is required, and circuit configuration Becomes complicated.
Therefore, in this embodiment, the charging charge of the capacitor C ₁ at the time of polarity reversal is reduced without separately providing the switching element Q ₇ .

Specifically, as shown in FIG. 19, a series circuit of diodes D ₃₀ and D ₃₁ whose cathodes are connected to both ends of the capacitor C _{1 and} whose anodes are connected to each other is connected in parallel to the capacitor C _1. , The commonly connected anodes of the diodes D ₃₀ and D ₃₁ , and the secondary winding L of the transformer T _1.
An inductance element L ₄ is connected between _{2 and} the connection point of the switching element Q ₂ .

Since the operation of the power supply device of this embodiment is the same as that of the above-described embodiment except when the polarity of the inverter section 2 is reversed, only the operation when the polarity is reversed will be described below. For example, a case will be described where the switching elements Q ₂ and Q ₃ are switched on and the switching elements Q ₁ and Q ₄ are switched on. At this time, the capacitor C ₁ is charged with the polarity shown in FIG.

Here, in the case of the present embodiment, when turning on the switching elements Q ₁ and Q ₄ , first, only the switching element Q ₄ is turned on. As a result, the capacitor C
₁ , switching element Q ₄ , inductance element L ₄ ,
The charge of the capacitor C ₁ is discharged through the path of the diode D ₃₀ and the capacitor C ₁ . And the capacitor C ₁
Time charges of is fully released, or by resonance of the capacitor C ₁ and the inductance element L _4, once the transferred energy in the inductance element L ₄ is returned to the capacitor C _1, the capacitor C ₁ and the state shown in The switching element Q ₁ is turned on at the time of charging with the opposite polarity. By doing so, an excessive current does not flow in the inverter unit 2 when the polarity is reversed. Moreover, the transformer T ₁
Since the charge charged in the capacitor C ₁ is not discharged through the path passing through the secondary winding L ₂ , the excessive current does not flow to the converter unit 1 side.

[0081] Incidentally, when switching from the ON state of the switching element Q _1, Q ₄ to a state where the switching element Q _2, Q ₃ is turned on, first the switching element Q ₂ on, capacitor C _1, the switching element Q ₂ , Inductance element L ₄ , diode D ₃₁ , capacitor C ₁
The charge of the capacitor C ₁ is discharged through the path. Therefore, as in the case where the switching elements Q ₂ and Q ₃ are switched from the ON state to the switching elements Q ₁ and Q ₄ , the excessive current does not flow in the converter unit 1 and the inverter unit 2. .

(Embodiment 12) In this embodiment, as shown in FIG. 20, the diode D in the embodiment 7 shown in FIG. 11 is used.
Inductors L ₄₁ and L ₄₂ as current limiting elements are connected in series to ₁ and D ₂ , and an inductance L ₄₃ as current limiting element is connected in series with the parallel circuit of the capacitor C ₁ and the discharge lamp LP. The connection point between the secondary windings L ₂₁ and L ₂₂ , the inductance elements L ₄₁ and L _42, and the switching element Q ₁ ,
Diodes D ₃₂ and D ₃₃ are connected between the respective connection points with Q _2.
Are connected. The inductance elements L _{41 to} L ₄₃ are electromagnetically coupled to each other, and their polarities are set to the polarities shown in the figure.

In the case of this embodiment, except when the polarity is reversed,
Switching element Q₁, Q₂When turning on,
Current is inductance element L₄₁~ L₄₃Flow through
21A to 21F except that
It is the same as the case of 7. In addition, the run flowing to the discharge lamp LP
Current i_LPIs shown in FIG. The operation when reversing the polarity is
It looks like this: Now switching element Q₁Is it on?
Switching element Q₂When is switched on,
Capacitor C₁Is charged to the polarity shown in FIG.
It Where capacitor C₁The voltage across both ends is V_CAnd
At this time, the transformer T₁The energy stored in
Inductance element L _{twenty two}The voltage induced in_LIs
And then V_L<V_CThen, the electric power is supplied through the route shown by a in FIG.
The flow flows. However, the current at this time is the inductance
Element L_{twenty two}And inductance element L₄₂, L₄₃Current limiting action
Is suppressed by.

Then, the capacitor C₁Voltage V across_CBut
By lowering the diode D ₂Is turned off,
Current flows through the route indicated by B in FIG.₁
The current due to the charging charge of the secondary winding L_{twenty two}Do not flow through
Become Therefore, the regenerative current on the primary side of the converter unit 1
Will be reduced. In addition, the inductance element L₄₃And Conden
SA C₁Resonance of capacitor C₁Is charged in reverse polarity
Therefore, the capacitor C ₁Causes a rest period in the current flowing through
This can be prevented only when the load is the discharge lamp LP.
It is possible to avoid problems such as fading.

The inductance element L₄₁~ L₄₃
And diode D₃₂, D₃₃, As shown in FIG.
Then, the inverter unit 1 may be configured. That is, FIG.
In case of, secondary winding L_{twenty one}, L_{twenty two}Without going through
Densa C₁The inductor to the path that discharges the charge
Element L₄₃Instead of the inductance element L₄₁, L ₄₂
Is to be inserted.

(Embodiment 13) In this embodiment, as shown in FIG. 23, two sets of the converter section 1 of Embodiment 12 shown in FIG. 20 are integrated, and basically the same as Embodiment 12. Operate. In the case of FIG. 23, one set is formed by adding a dash to the reference numeral, and one set is formed by not adding a dash. The number of sets may be two or more. In this way, when a plurality of converter sections 1 are integrated, switching elements Q ₀₁ and Q ₀₂ having a low withstand voltage can be used.

(Embodiment 14) FIG. 24 shows the present embodiment.
The present embodiment is an embodiment corresponding to the case where the power supply to the load circuit 3 needs to have different voltage values depending on the polarities. The case of FIG. 24 corresponds to the case where it is necessary that the voltage V _C across the capacitor C ₁ has a low voltage when generated with the illustrated polarity and the voltage when a voltage with the opposite polarity occurs is high. At this time, since the voltage induced in the secondary winding L ₂₂ of the transformer T ₁ is low, only the secondary winding L ₂₂ is used as the current limiting element for reducing the current due to the charge charged in the capacitor C _1. . In other words, the present embodiment is a modification of the circuit shown in FIG. 22 to deal with the case where the voltage value supplied to the load circuit 3 differs depending on the polarity.

By the way, in each of the above-described embodiments, the case of applying a voltage having a substantially rectangular wave shape to the load circuit 3 has been described, but a trapezoidal wave shape or a sine wave shape may be applied. The sinusoidal shape can be realized by changing the on-duty of the switching element Q ₀ according to the peak value of the sinusoidal wave. Further, the DC power supply V _S is that the AC power obtained by rectifying or rectified and smoothed, those that have been DC-DC conversion, or whatever such as a battery for vehicles. Further, the converter unit 1 may be a forward type or a chopper type other than the flyback type described above. Furthermore, switching elements not particularly limited include bipolar transistors, IGBTs, M
It may be a CT, a thyristor, or the like. However,
It goes without saying that in the case of a switching element other than the FET, it is necessary to connect a diode in antiparallel.

[0089]

As described above, the invention of claim 1 is a DC power supply, a converter section for converting the voltage of the DC power supply, an inverter section for converting DC power supplied from the converter section to AC power, and an inverter. A capacitor connected to the output of the unit, a load circuit connected in parallel with the capacitor and supplied with the voltage across the capacitor as a power source, and an impedance element that reduces the electric charge charged in the capacitor when the polarity of the inverter unit is reversed. Since a loop forming means is formed between the capacitor and the impedance element to form a loop for discharging the charge charged in the capacitor at the time of polarity reversal, the charge charge of the capacitor at the time of polarity reversal can be reduced by the impedance element, This charge is used as a power source to reduce the current flowing through the inverter and converter. It is possible to prevent an overcurrent from flowing in the polarity inversion time.

According to a second aspect of the present invention, the loop control means controls the switching of the switching element of the inverter so as to form a path for discharging the charge stored in the capacitor through the impedance element when the polarity is inverted. Since the switching element of the inverter section is also used as the loop forming means, the circuit configuration can be simplified.

According to the fourth aspect of the invention, when the FET is used as the switching element, the parasitic diode of the switching element is bypassed, and loop forming means for forming a loop for discharging the charge charged in the capacitor to the impedance element is provided. Therefore, when an FET with a slow recovery time of the parasitic diode is used as the switching element that constitutes the inverter part, the charge stored in the capacitor at the time of polarity reversal is not discharged through the parasitic diode, and the surge occurs when the parasitic diode is turned off. It is possible to prevent a voltage from being generated.

According to the fourth aspect of the present invention, since the inductance element is used as the impedance element, the inductance element discharges the energy due to the charging charge discharged from the capacitor to the capacitor, and after the polarity is reversed, the capacitor is rapidly changed to the opposite polarity. It can be charged, and the rise of the capacitor connected to the output of the inverter unit at the time of polarity reversal can be accelerated.

As described in claim 5, since the inductance element is used as the impedance element and the inductance elements are electromagnetically coupled to each other, the inductance element can be integrally wound around the coil bobbin, and the impedance element can be miniaturized. can do. According to the invention of claim 6, when a plurality of inductance elements are used as the impedance element, the inductance elements are electromagnetically coupled to each other as shown in claim 6, so that the inductance element is wound around the coil bobbin integrally. The impedance element can be made compact.

According to a tenth aspect of the invention, as in the power supply apparatus of the ninth aspect, in the transformer provided with a transformer for insulating and separating the DC power source and the inverter part, the secondary winding of the transformer has a polarity. Since it is also used as an impedance element to reduce the electric charge charged in the capacitor at the time of inversion, the regenerative current on the secondary side of the transformer can be suppressed by the inductance component of the secondary winding, and it can be added to the primary side of the transformer. Since the current limiting means for limiting the regenerative current to the DC power source or the blocking means for blocking the regenerative current is provided, the regenerative current can be suppressed or blocked by the charge of the capacitor on the primary side of the transformer.

According to the eleventh aspect of the invention, in the power supply device according to the ninth aspect, the current limiting element is inserted in the regenerative current loop due to the charge charged in the capacitor at the time of polarity reversal on the secondary side of the transformer. The regenerative current can be suppressed by the charge of the secondary side capacitor. Claim 1
In the second aspect of the invention, since the switching means for short-circuiting the current limiting element during the period other than the polarity reversal period is provided, it is possible to eliminate the influence of the current limiting element during the period other than the polarity reversal period.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the above.

3A to 3C are circuit diagrams showing impedance elements having different configurations.

FIG. 4 is a circuit diagram of a second embodiment.

FIG. 5 is an operation explanatory diagram when the polarity of the above inverter unit is reversed.

FIG. 6 is a circuit diagram of a third embodiment.

FIG. 7 is a circuit diagram of a fourth embodiment.

FIG. 8 is an explanatory diagram of an operation when the polarity of the above inverter unit is reversed.

FIG. 9 is a circuit diagram of a fifth embodiment.

FIG. 10 is a circuit diagram of a sixth embodiment.

FIG. 11 is a circuit diagram of a seventh embodiment.

FIG. 12 is an explanatory diagram of an operation of the above.

FIG. 13 is a circuit diagram of an eighth embodiment.

FIG. 14 is an explanatory diagram of an operation of the above.

FIG. 15 is a circuit diagram of the ninth embodiment.

FIG. 16 is a circuit diagram specifically showing the main part of the above.

FIG. 17 is an explanatory diagram of the same operation as above.

FIG. 18 is a circuit diagram of the tenth embodiment.

FIG. 19 is a circuit diagram of the eleventh embodiment.

FIG. 20 is a circuit diagram of a twelfth embodiment.

FIG. 21 is an operation explanatory diagram of the above.

FIG. 22 is a circuit diagram of a modification of the twelfth embodiment.

FIG. 23 is a circuit diagram of the thirteenth embodiment.

FIG. 24 is a circuit diagram of a fourteenth embodiment.

FIG. 25 is a circuit diagram of a conventional example.

FIG. 26 is a circuit diagram of another conventional example.

[Explanation of symbols]

1 the converter circuit 2 inverter 3 the load circuit V _S DC power supply Q ₀ to Q ₄ switching elements C ₁ capacitor _{D 0, D 1, D 2} , D 10 ~D 13 diode Z impedance elements L _1, L _11, L ₁₂ inductance Element L ₂ , L ₂₁ , L ₂₂ Secondary winding T ₁ Transformer LP Discharge lamp

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiro Nakamura 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd.

Claims (14)

[Claims] 1. A DC power supply, a converter section for converting the voltage of the DC power supply, an inverter section for converting DC power supplied from the converter section to AC power, and a capacitor connected to the output of the inverter section. A load circuit that is connected in parallel with the capacitor and is supplied with the voltage across the capacitor as a power source, and an impedance element that reduces the charge charged in the capacitor when the polarity of the inverter unit is reversed.
A power supply device comprising: a loop forming means for forming a loop for discharging a charge charged in the capacitor between the capacitor and the impedance element at the time of polarity reversal. 2. The loop forming means is constituted by a switching control means for controlling switching of a switching element of an inverter unit so as to form a path for discharging a charge charged in a capacitor through an impedance element when polarity is reversed. The power supply device according to claim 1, wherein: 3. The inverter unit is constituted by connecting switching elements in a bridge connection, and the parallel circuit of the capacitor and the load circuit is connected between the connection points of the switching elements connected in series to connect in series. Rectifying element is inserted in series with each switching element, and an impedance element that reduces the electric charge charged in the capacitor at the time of polarity reversal is connected between the connection points of each rectifying element and the switching element. The power supply device according to claim 2. 4. When a FET is used as a switching element, the parasitic diode of the switching element is bypassed, and a loop forming means for forming a loop for discharging the charge charged in the capacitor to the impedance element is provided. The power supply device according to claim 2. 5. The power supply device according to claim 1, wherein an inductance element is used as the impedance element. 6. The power supply device according to claim 5, wherein, when a plurality of inductance elements are used as the impedance element, the inductance elements are electromagnetically coupled to each other. 7. The power supply device according to claim 1, wherein the load circuit is a series circuit of a discharge lamp and an inductance element. 8. The power supply device according to claim 1, wherein the switching control means controls the switching of the switching element so that the output voltage waveform becomes a substantially rectangular wave. 9. The power supply device according to claim 1, wherein the converter section includes a transformer that insulates and separates between the DC power supply and the inverter section. 10. The secondary winding of the transformer is also used as an impedance element for reducing the electric charge charged in the capacitor at the time of polarity reversal, and the regenerative current to the DC power source is limited to the primary side of the transformer. 10. The power supply device according to claim 9, further comprising a flow means or a blocking means for blocking. 11. The power supply device according to claim 9, wherein a current limiting element is inserted in the regenerative current loop due to the charge charged in the capacitor during polarity reversal on the secondary side of the transformer. 12. The power supply device according to claim 11, further comprising switching means for short-circuiting the current limiting element in a period other than the polarity inversion period. 13. The converter section includes a transformer having two secondary windings, and two switching elements are connected in series at both ends of a series circuit of the secondary windings of each transformer.
A parallel circuit of a capacitor and a load circuit is connected between the connection point of the secondary winding and the connection point of the switching element, and the current due to the charging charge of the capacitor at the time of polarity reversal is discharged by bypassing the secondary winding. The power supply device according to claim 11, further comprising: a loop forming unit that forms a loop, and a current limiting element that limits the loop current. 14. The power supply device according to claim 12, wherein the converter section is configured by using a plurality of sets of converters.