JP3400626B2 - Power supply - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for converting an input voltage into a high frequency voltage, and in particular, it includes one or more conversion circuits each including two switching elements connected in series and alternately turned on and off. The present invention relates to a power supply device in which two switching elements are driven by the output of one transformer.

[0002]

2. Description of the Related Art Conventionally, a power supply device called a half bridge type as shown in FIG. 6 has been proposed. This power supply device has two switching elements (bipolar transistor, MOSFET, IGBT, etc.) connected in series.
A conversion circuit including a pair of Q ₁ and Q ₂ is provided, and a series circuit of _two switching elements Q ₁ and Q ₂ forming the conversion circuit is connected to a DC power source E. The DC power source E may be of a constant voltage such as a battery power source or may be of a voltage varying like a pulsating current power source obtained by full-wave rectifying a commercial power source. The paired switching elements Q ₁ and Q ₂ are on / off controlled by inputting a rectangular wave-shaped high frequency signal output from the high frequency oscillation circuit OSC to a control terminal (base or gate) via a transformer T. The transformer T includes two secondary windings n ₂₁ and n _22, and the output voltage of the high frequency oscillator circuit OSC is applied to the primary winding n ₁ . In addition, each secondary winding n ₂₁ , n
₂₂ is such that the connection polarities of the switching elements Q ₁ and Q _{2 to} the control terminals are opposite to each other. When one switching element Q ₁ is forward biased, the other switching element Q ₂ is reverse biased. I am doing it. Therefore, the switching elements Q ₁ and Q ₂ are alternately turned on and off by the output of the high frequency oscillation circuit OSC. Further, a series circuit of a series resonance circuit RS including a series circuit of an inductor L and a capacitor C and a load circuit LD is connected in parallel to the switching element Q ₂ on the low side (negative side of the DC power supply E).

However, the potential at the connection point of the switching elements Q ₁ and Q ₂ becomes the positive potential of the DC power source E during the ON period of the switching element Q ₁ , and the DC power source E during the ON period of the switching element Q _2. Becomes the negative electrode potential of. That is, the positive electrode potential and the negative electrode potential of the DC power source E are alternately applied to the load circuit LD according to the ON / OFF of the switching elements Q ₁ and Q ₂ . However, the capacity of the capacitor C is sufficiently small, the power supply to the load circuit LD by the charge of the capacitor C is negligible, and the resonance frequency of the series resonance circuit RS is almost equal to the output frequency of the high frequency oscillation circuit OSC. Are set equal. Therefore, the switching elements Q ₁ and Q ₂ can be turned on and off in the state of zero current, and the switching loss can be reduced.

With the above configuration, the load circuit LD includes
A rectangular wave voltage having a frequency equal to the drive frequency, which is the output frequency of the high frequency oscillation circuit OSC, can be applied. Further, since the resonance frequency of the series resonance circuit RS is set to be substantially equal to the drive frequency, the harmonic component is removed and a rectangular wave voltage having a frequency equal to the drive frequency is applied to the load circuit LD.

[0005]

By the way, in the above configuration, since the transformer T having the two secondary windings n ₂₁ and n ₂₂ is used, it is necessary to turn off one of the switching elements Q ₁ and Q _2. When ringing occurs, the operation of the other switching elements Q ₁ and Q ₂ is affected via the transformer T. In particular, when the drive frequency is about 10 MHz, the time from the occurrence of ringing to the end of the ringing is almost equal to the on / off cycle of the switching elements Q ₁ and Q ₂ , so when the drive frequency is set to 10 MHz or more. Will have the following ringing before it is fully attenuated after the ringing occurs.
As a result, the ringing caused by the turn-off of each of the switching elements Q ₁ and Q ₂ interferes with each other, and the voltage variation due to the ringing becomes large as shown in FIG. 7. As described above, the switching loss increases as the voltage fluctuation due to ringing increases. That is, the conversion efficiency of the power supply device decreases.

In order to solve this type of problem, it is sufficient to use switching elements Q ₁ and Q _{2 in} which the time from the occurrence of ringing to the end is sufficiently short. However, such switching elements Q ₁ and Q _{2 are used.} Will use a specially shaped package, leading to a problem of high cost. The present invention has been made in view of the above reasons,
It is an object of the present invention to provide a power supply device that operates with high efficiency without using a special switching element even if the drive frequency becomes high.

[0007]

According to the invention of claim 1, one or more sets of conversion circuits each including two switching elements connected in series and alternately turned on and off are connected between both ends of the DC power supply. , A power supply device that generates a high frequency voltage at a connection point of two switching elements forming a pair and applies the high frequency voltage to a load circuit through a resonance circuit having a resonance frequency substantially equal to a drive frequency for turning on / off the switching element. Therefore, the two switching elements that form a pair are controlled to be turned on and off by inputting the output of the secondary winding provided in one transformer to the control terminals, respectively, and between the control terminals of the two switching elements that form a pair. Vibrations caused by ringing higher than the driving frequency above
A high frequency attenuating element for attenuating a specific frequency, which is the frequency of the voltage, is provided.

According to this structure, even if ringing occurs when one of the two switching elements forming a pair is turned off, a high-frequency attenuation element exists, so that an oscillating voltage is input to the control terminal of the other switching element. It is difficult to prevent the vibration voltage from increasing and the oscillating voltage can be prevented from increasing. That is, even if the drive frequency for turning on / off the switching element is increased, the ringing that occurs when the two switching elements that form a pair are turned off does not interfere with each other, and it is possible to suppress an increase in switching loss due to voltage fluctuation. As a result, it is not necessary to use an expensive switching element in a special package, and it is possible to provide a power supply device having a relatively low cost and a high driving frequency.

According to a second aspect of the present invention, in the first aspect of the present invention, the high frequency attenuating element is a control terminal of at least one of the two switching elements forming a pair and a transformer.
The impedance for the specific frequency is set higher than that for the driving frequency by being inserted between the secondary winding and the next winding. According to a third aspect of the present invention, in the first aspect, the high frequency attenuating element is inserted between a control terminal of at least one of the two switching elements forming a pair and a ground side end of the DC power source. The impedance for the specific frequency is set lower than the impedance for the drive frequency.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the high frequency attenuating element is a transformer core, and the magnetic permeability for the specific frequency is set lower than the magnetic permeability for the drive frequency. The invention according to claim 2 to claim 4 is a preferred embodiment of the invention according to claim 1, which has an effect of suppressing a high frequency component of the vibration component of the input signal to the control terminal in any configuration. It is possible to suppress the increase of the oscillating voltage due to the ringing.

According to the invention of claim 5, two sets of conversion circuits are connected by connecting two or more sets of switching elements, which are connected in series and are alternately turned on and off, between both ends of the DC power supply. A power supply device that generates a high frequency voltage at the connection point of the switching element and applies the high frequency voltage to the load circuit via a resonance circuit having a resonance frequency that is approximately equal to the drive frequency that turns the switching element on and off, and forms a set. The two switching elements are on / off controlled by inputting the output of the secondary windings provided in one transformer to the control terminals, respectively. The transformer has two primary windings, and both primary windings are ringing. Vibration caused by
Connected in series Ru Tei <br/> impedance for a particular frequency is the frequency of the voltage via a high-frequency attenuation element is set higher than the impedance for the drive frequency.

With this configuration, even if ringing occurs when one of the two switching elements forming a pair is turned off, the high frequency component due to the ringing is attenuated by the high frequency attenuation element provided on the primary side of the transformer. The secondary winding output input to the control terminal of the other switching element contains almost no high-frequency component due to ringing, and as a result, the increase in oscillating voltage can be suppressed,
It is possible to suppress an increase in switching loss.

According to a sixth aspect of the present invention, in the first to fifth aspects of the present invention, the load circuit is formed by enclosing a discharge gas-sealed valve and a high-frequency current which is electromagnetically coupled to the internal space of the valve. An electrodeless discharge lamp including an induction coil that excites the discharge gas inside the bulb to emit light by the high-frequency electromagnetic field.

[0014]

DETAILED DESCRIPTION OF THE INVENTION

(Embodiment 1) In this embodiment, as shown in FIG. 1, the basic structure is the same as that of the conventional circuit shown in FIG. 6, and the members with the same reference numerals have the same functions. There is. However,
The present embodiment includes inductors L ₁₁ and L ₁₂ and capacitors C ₁₁ and C ₁₂ between the secondary windings n ₂₁ and n ₂₂ of the transformer T and the control terminals of the switching elements Q ₁ and Q _2. This is different from the conventional circuit in that the parallel resonant circuits RS ₁ and RS ₂ are respectively inserted. The parallel resonant circuits RS ₁ and RS ₂ have low impedance with respect to the drive frequency for turning on / off the switching elements Q ₁ and Q _{2, and} with respect to the frequency of the oscillating voltage generated by ringing (hereinafter referred to as the ringing frequency). Set to have high impedance.

When such parallel resonant circuits RS ₁ and RS ₂ are used, even if ringing occurs due to the turning off of one of the switching elements Q ₁ and Q ₂ , the oscillating current due to ringing causes the oscillating current due to the ringing to the other switching element Q 2. ₁ , Q ₂
Parallel resonant circuits RS ₁ and RS inserted in the control terminals of
_The other switching elements Q ₁ and Q are blocked by ₂
It is possible to suppress an increase in the oscillating voltage caused by ringing without being input to the _second control terminal. As a result, the voltage fluctuation due to ringing is reduced, the switching loss is reduced, and the reduction in conversion efficiency of the power supply device can be suppressed.

As the load circuit LD, for example, as shown in FIG. 2, a load circuit LD including an electrodeless discharge lamp La and a matching circuit M can be used. Electrodeless discharge lamp La
Is provided with a valve B filled with a discharge gas containing a rare gas and an induction coil Co electromagnetically coupled to the internal space of the valve B, and is formed by supplying a high frequency current to the induction coil Co. By causing a high-frequency electromagnetic field to act on the discharge gas in the internal space of the bulb B, the discharge gas is excited to emit light. The matching circuit M is connected between the capacitor Ca inserted between the series resonance circuit RS and the induction coil Co, the connection point between the series resonance circuit RS and the capacitor Ca, and the negative electrode of the DC power supply E. And a capacitor Cb.

Here, parallel resonant circuits RS ₁ and RS ₂ are inserted between the secondary windings n ₂₁ and n ₂₂ and the control terminals of the switching elements Q ₁ and Q ₂ , respectively. Even if only _{one of} RS ₁ and RS ₂ is provided, the effect of suppressing the increase of the oscillating voltage can be obtained. Other configurations and operations are the same as those of the conventional circuit, and therefore description thereof will be omitted.

(Embodiment 2) In this embodiment, as shown in FIG. 3, a transformer T having two primary windings n ₁₁ and n ₁₂ in the conventional circuit shown in FIG. 6 is used. , A parallel resonance circuit RS ₀ composed of an inductor L ₀ and a capacitor C ₀ is connected in series between both primary windings n ₁₁ and n ₁₂ . In the series circuit of the primary windings n ₁₁ and n ₁₂ and the parallel resonant circuit RS ₀ , the primary windings n ₁₁ and n ₁₂ are connected with different polarities via the parallel resonant circuit RS ₀ .

The parallel resonant circuit RS ₀ is set to have a low impedance with respect to the driving frequency and a high impedance with respect to the ringing frequency. Here, ringing tends to occur due to the release of the energy accumulated in the transformer T when one of the switching elements Q ₁ and Q ₂ is turned off, but the primary windings n ₁₁ and n _{12 of} the transformer T serve as high-frequency attenuation elements. Of the secondary winding n ₂₁ connected to the control terminals of the other switching elements Q ₁ and Q ₂ with almost no oscillating voltage due to ringing due to the serial connection via the parallel resonance circuit RS ₀ of , N ₂₂ hardly generate an oscillating voltage due to ringing. That is, even if ringing occurs due to turn-off of one of the switching elements Q ₁ and Q ₂ , the other switching element Q ₁
The influence on ₁ and Q ₂ is reduced, and as a result, the increase of the oscillating voltage can be suppressed. Other configurations and operations are similar to those of the first embodiment.

(Embodiment 3) In this embodiment, as shown in FIG. 4, between the control terminals of the switching elements Q ₁ and Q ₂ and the negative electrode of the DC power source E in the conventional circuit shown in FIG. , Inductors L ₁₃ , L ₁₄ and capacitors C ₁₃ ,
It has a configuration in which the series resonance circuits RS ₃ and RS _{4 including} C ₁₄ are connected. Each of the series resonance circuits RS ₃ and RS ₄ has a high impedance with respect to the driving frequency and a low impedance with respect to the ringing frequency. Therefore, the oscillating current generated by ringing is
By flowing into the series resonance circuits RS ₃ and RS ₄ , the switching terminals Q ₁ and Q ₂ are not input to the control terminals, and as a result, the increase of the oscillating voltage due to ringing can be suppressed and the switching loss can be reduced. Other configurations and operations are similar to those of the first embodiment.

(Embodiment 4) The present embodiment has the same structure as the conventional circuit shown in FIG. 6, but uses a transformer T having a core magnetic permeability as shown in FIG. Is characterized by. That is, the core of the transformer T has a high magnetic permeability with respect to the driving frequency fs and has a ringing frequency f.
It is formed to have a low magnetic permeability with respect to r. Here, the core is formed of, for example, ferrite, and the composition is adjusted so as to obtain a desired magnetic permeability.

If the magnetic permeability of the core of the transformer T is set as shown in FIG. 5, the oscillating voltage caused by the ringing of one of the switching elements Q ₁ and Q ₂ passes through the transformer T and the other switching element Q ₁ , Q ₂ is not transmitted, and the increase of the oscillating voltage is suppressed. Other configurations and operations are similar to those of the first embodiment.

[0023]

According to the first aspect of the present invention, one set or more of the conversion circuits, each of which is composed of two switching elements connected in series and turned on and off alternately, are connected between both ends of the DC power supply to form a set. A power supply device which generates a high frequency voltage at a connection point of two switching elements and applies the high frequency voltage to a load circuit through a resonance circuit having a resonance frequency substantially equal to a drive frequency for turning on / off the switching elements. The two switching elements are controlled to be turned on and off by inputting the output of the secondary winding provided in one transformer to the control terminals, respectively. Is the frequency of the oscillating voltage caused by ringing higher than the above driving frequency.
That high frequency attenuation element for attenuating a specific frequency are those is provided, even if ringing with the one of the turn-off of the two switching elements comprising a set of other Suichinngu elements by high frequency attenuation element is present It is difficult to input the oscillating voltage to the control terminal, and it is possible to prevent the oscillating voltage from increasing. That is, even if the drive frequency for turning on / off the switching element is increased, the ringing that occurs when the two switching elements in the pair are turned off does not interfere with each other, and it is possible to suppress an increase in switching loss due to voltage fluctuation, which is expensive. It is possible to provide a power supply device having a relatively low cost and a high drive frequency without using a switching element of a special package.

According to a second aspect of the present invention, a high frequency attenuating element is inserted between the control terminal of at least one of the two switching elements forming a pair and the secondary winding of the transformer,
The impedance for the specific frequency is set higher than the impedance for the driving frequency, or as in the invention of claim 3, the control terminal of at least one of the two switching elements forming a pair and the ground side end of the DC power supply are connected. A high frequency attenuating element is inserted between them to set the impedance for a specific frequency lower than the impedance for a driving frequency, or like the invention of claim 4, the transformer core is used as a high frequency attenuating element to drive the magnetic permeability for a specific frequency. By setting the magnetic permeability lower than the frequency, the effect of suppressing the high frequency component of the vibration component of the input signal to the control terminal can be obtained, and as a result, the increase of the oscillating voltage due to ringing can be suppressed. .

According to a fifth aspect of the present invention, by connecting one set or more of one set of conversion circuits composed of two switching elements connected in series and alternately turned on and off between both ends of the DC power supply, two sets of conversion circuits are formed. A power supply device that generates a high frequency voltage at the connection point of the switching element and applies the high frequency voltage to the load circuit via a resonance circuit having a resonance frequency that is approximately equal to the drive frequency that turns the switching element on and off, and forms a set. The two switching elements are on / off controlled by inputting the output of the secondary windings provided in one transformer to the control terminals, respectively. The transformer has two primary windings, and both primary windings are ringing. Vibration caused by
When the impedance for a specific frequency, which is the frequency of the voltage, is connected in series via a high-frequency attenuation element whose impedance is set higher than the impedance for the driving frequency, and when one of the two switching elements forming a pair is turned off. Even if ringing occurs in the secondary winding output, the high frequency component due to the ringing is attenuated by the high frequency attenuation element provided on the primary side of the transformer. Therefore, the secondary winding output input to the control terminal of the other switching element is accompanied by the ringing. There is an advantage that the high frequency component is hardly contained, and as a result, the increase of the oscillating voltage can be suppressed and the increase of the switching loss can be suppressed.

According to a sixth aspect of the present invention, the discharge gas inside the bulb is excited by a bulb filled with a discharge gas and a high frequency electromagnetic field that is electromagnetically coupled to the inner space of the bulb and is formed by energizing a high frequency current. An electrodeless discharge lamp including an induction coil for emitting light is provided in the load circuit, and the power supply device according to the invention of each of the above claims is suitable for this type of load circuit.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment.

FIG. 2 is a specific circuit diagram showing the first embodiment.

FIG. 3 is a circuit diagram showing a second embodiment.

FIG. 4 is a circuit diagram showing a third embodiment.

FIG. 5 is a diagram showing characteristics of a transformer core used in a fourth embodiment.

FIG. 6 is a circuit diagram showing a conventional example.

FIG. 7 is an operation explanatory view showing a problem of the conventional example.

[Explanation of symbols]

B Valve Co induction coil E DC power source La electrodeless discharge lamp LD load circuit n ₁₁ 1 winding n ₁₂ 1 winding n ₂₁ 2 winding n ₂₂ 2 winding n ₁ 1 winding OSC frequency oscillation circuit Q ₁ switching element Q ₂ switching element RS parallel resonant circuit RS ₀ series resonant circuit RS ₁ parallel resonant circuit RS ₂ parallel resonant circuit RS ₃ series resonant circuit RS ₄ series resonant circuit T transformer

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Anan 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Motohiro Saimi, 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd. ( 56) References JP-A-5-13185 (JP, A) JP-A-7-302128 (JP, A) JP-A-6-215894 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02M 7/48 H02M 7/5383 H02M 7/5387 H05B 41/24

Claims (6)

(57) [Claims] 1. A connection of two switching elements forming a set by connecting one set or more of a set of conversion circuits composed of two switching elements connected in series and turned on and off alternately between both ends of a DC power supply. Generate a high frequency voltage at the point,
A power supply device for applying a high frequency voltage to a load circuit via a resonance circuit having a resonance frequency substantially equal to a drive frequency for turning on / off the switching element, wherein two switching elements forming a pair are provided in one transformer. ON / OFF control is performed by inputting the output of the next winding to each control terminal, and ringing higher than the above drive frequency is provided at a key point between the control terminals of the two switching elements forming a pair.
And a high frequency attenuating element for attenuating a specific frequency which is a frequency of an oscillating voltage generated by the power source device. 2. The high frequency attenuating element is inserted between the control terminal of at least one of the two switching elements forming a pair and the secondary winding of the transformer, and the impedance for the specific frequency is for the driving frequency. The power supply device according to claim 1, wherein the power supply device is set higher than the impedance. 3. The high frequency attenuating element is inserted between at least one control terminal of the two switching elements forming a pair and the ground side end of the DC power supply, and the impedance at the specific frequency is at the driving frequency. The power supply device according to claim 1, wherein the power supply device is set to be lower than the impedance. 4. The power supply device according to claim 1, wherein the high frequency attenuating element is a core of a transformer, and the magnetic permeability for the specific frequency is set lower than the magnetic permeability for the drive frequency. 5. A connection of two switching elements forming a set by connecting one or more sets of conversion circuits each including two switching elements connected in series and alternately turned on and off between both ends of a DC power supply. Generate a high frequency voltage at the point,
A power supply device for applying a high frequency voltage to a load circuit via a resonance circuit having a resonance frequency substantially equal to a drive frequency for turning on / off the switching element, wherein two switching elements forming a pair are provided in one transformer. ON / OFF control is performed by inputting secondary winding outputs to control terminals, the transformer has two primary windings, and both primary windings are frequencies of an oscillating voltage generated by ringing. A power supply device, which is connected in series via a high-frequency attenuation element whose impedance with respect to frequency is set higher than that with respect to the drive frequency. 6. The load circuit excites the discharge gas inside the bulb with a bulb filled with a discharge gas and a high frequency electromagnetic field that is electromagnetically coupled to the interior space of the bulb and is formed by energizing a high frequency current. The power supply device according to any one of claims 1 to 5 , further comprising an electrodeless discharge lamp including an induction coil that emits light.