JPH10215583A - Power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive power supply in which the variation rate of circuit efficiently η can be decreased, even if the voltage being applied to the primary of a drive transformer is varied due to the variations in the characteristics of components. SOLUTION: This power supply comprises a high-frequency power supply having two switching elements-connected in series and supplying a load with a high-frequency AC voltage produced by converting a DC voltage, a drive transformer having a primary winding n1, two secondary windings n21, n22 connected in series with the control terminal of two switching elements and a magnetic core 10, and a driver for driving the two switching elements by applying a voltage to the primary winding n1 of the drive transformer, wherein the secondary windings n21, n22 are arranged at a constant interval, so that they do not make tight contact with each other, i.e., wound while being spaced apart at every turn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply.

[0002]

2. Description of the Related Art FIG. 6 shows a circuit diagram according to the present invention.

[0003] This circuit is an electrodeless discharge lamp in which a discharge gas (eg, mercury and rare gas) such as an inert gas or metal vapor is sealed in a spherical glass bulb which is transparent or has a fluorescent film applied to the inner wall. An electric lamp 1, a high-frequency power supply coil 2 disposed close to the periphery of the lamp 1, a high-frequency power supply 3 for supplying high-frequency power to the high-frequency power supply coil 2, and a high-frequency power supply coil 2 and the high-frequency power supply 3. A matching circuit 4 is provided that eliminates reflection by performing both matchings and efficiently supplies high-frequency power to the electrodeless discharge lamp 1. Then, a high-frequency magnetic field of several megahertz to several hundreds of megahertz is passed from the high-frequency power supply 3 to the high-frequency power supply coil 2 to generate a high-frequency magnetic field in the high-frequency power supply coil 2, thereby supplying high-frequency power to the electrodeless discharge lamp 1. Then, high-frequency plasma is generated in the electrodeless discharge lamp 1 to generate ultraviolet light or visible light. The high-frequency power source 3 is a quartz oscillator X
An oscillation circuit 5 using the same, and amplifying the output of the oscillation circuit 5;
A preamplifier 6 configured by a so-called class C amplifier circuit, and a main amplifier 7 configured by a so-called class D amplifier circuit including field effect transistors (hereinafter, referred to as switching elements) Q1 and Q2, an inductor L2, and a capacitor C2.
And a primary winding n1, secondary windings n21 and n22, and a magnetic core.
And a drive transformer T for transmitting the power to the motor. The drive device 9 is composed of the oscillation circuit 5 and the preamplifier 6. At both ends of the primary winding n1 of the drive transformer T, a variable capacitance capacitor VC (hereinafter, referred to as a variable capacitor VC).
Are connected in parallel, and when the variable capacitor VC is changed, the switching elements Q1,
The gate-source voltage VGS of Q2 is adjusted, and the output of the high-frequency power supply 3 can be controlled. For example, when IRF710 manufactured by IR is used as the switching elements 01 and Q2, a control voltage (hereinafter, referred to as a gate-source voltage) is used.
VGS has a substantially sinusoidal voltage waveform, and its peak value is set to 10 to 15V. Here, a DC power supply E1 is used as a power supply of the main amplifier 7, and a DC power supply E2 is used as a power supply of the drive device 9.

FIG. 7 is a schematic perspective view of a driving transformer T which is a conventional example according to the present invention.

[0005] The drive transformer T uses, for example, a toroidal core as the magnetic core 10, and winds a primary winding n 1 and secondary windings n 21 and n 22 around the toroidal core 10.
The secondary winding n21 and the secondary winding n22 are paired, and the secondary windings n21 and n22 adjacent to each other do not intersect and are close to each other to form a bifilar winding.

FIG. 8 shows a characteristic diagram of an amplitude change of the gate-source voltage VGS when the variable capacitor VC is changed.
Here, the gate-source voltage VGS shown in FIG. 8 is obtained when only the DC power supply E2 is turned on. This is because the high-frequency ripple is superimposed on the gate-source voltage VGS immediately after the DC power supply E1 is turned on. Since it is a variable condenser VC
This is because it is difficult to read the amplitude of the gate-source voltage VGS at the time of change. According to FIG.
, The gate-source voltage VGS changes substantially in a parabolic manner, and has a peak value VGSp when the capacitance value of the variable capacitor VC is VCp. This indicates that resonance occurs between the variable condenser VC and the driving transformer T.

Next, a dummy load Ro having an impedance equivalent to the combined impedance of the electrodeless discharge lamp 1 and the matching circuit 4 is connected to the output terminal of the main amplifier 7, and in this state, both the DC power supply E1 and the DC power supply E2 are connected. FIG. 9 shows the waveform of the gate-source voltage VGS of the switching element Q2 when the power supply is turned on, and FIG. FIG. 10 shows a curve in which the circuit efficiency η becomes minimum around the capacitance value VCp. The operating frequency of the high frequency power supply 3 is 13.56 MHz.
z.

[0008]

However, in the above conventional example, as shown in FIG. 10, for example, the circuit efficiency .eta.
From 4%, it decreases to about 77% near the capacitance value VCp, and the rate of change of the circuit efficiency η with respect to the value of the variable condenser VC also increases. Therefore, even if the variable capacitor VC is initially set to maximize the circuit efficiency η, the voltage is applied to the primary winding n1 due to a change over time in the characteristics of the components in the peripheral circuit of the primary winding n1. This causes a problem that the voltage is changed and the circuit efficiency η is greatly reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to reduce the variation in the voltage applied to the primary side of a driving transformer due to a change in the characteristics of components. Another object of the present invention is to provide a power supply device capable of reducing the rate of change in circuit efficiency η at low cost.

[0010]

In order to solve the above problems, according to the first aspect of the present invention, two serially connected 2
A high-frequency power supply that has two switching elements and converts a DC voltage into an AC high-frequency voltage and supplies it to a load; two secondary windings connected in series to the primary winding and control terminals of the two switching elements, respectively; A drive transformer having a wire, a primary winding, and a magnetic core wound with two secondary windings; and a drive device for driving two switching elements by applying a voltage to the primary winding of the drive transformer. And the secondary winding is wound in a direction to shorten the on-time of the switching element and secure the on-time.

According to the second aspect of the invention, the two secondary windings are wound at equal intervals every turn.

According to the third aspect of the present invention, the two secondary windings are wound at equal intervals between all the secondary windings.

According to a fourth aspect of the present invention, the two secondary windings are wound without contact with each other.

According to a fifth aspect of the present invention, the two secondary windings are paired and bifilar wound.

According to a sixth aspect of the present invention, the drive transformer is characterized in that the primary winding and the secondary winding are wound in directions away from each other.

According to a seventh aspect of the present invention, the primary winding is closely wound at every turn at least on the inner surface side of the magnetic core.

According to the invention described in claim 8, the magnetic core is a toroidal core.

According to a ninth aspect of the present invention, the magnetic core is a carbonyl iron-based core.

According to a tenth aspect of the present invention, the magnetic core is a Ni—Zn ferrite core.

According to an eleventh aspect of the present invention, the drive device drives the switching element separately.

According to a twelfth aspect of the present invention, the high frequency power supply is a class D amplifier circuit.

According to the thirteenth aspect, the operating frequency of the high-frequency power source is 0.5 MHz or more.

According to the fourteenth aspect, the load is:
It is characterized by including at least an electrodeless discharge lamp.

[0024]

Embodiment

(Embodiment 1) FIG. 1 is a schematic perspective view of a first embodiment according to the present invention.

The difference from the conventional example shown in FIG. 7 is that the secondary windings n21 and n22 are wound at equal intervals and so as not to be in close contact with each other, that is, at a distance from each other every turn. The same components as those of the conventional example are denoted by the same reference numerals, and description thereof is omitted.

Next, the operation will be briefly described. DC power supply E
2 shows the waveform of the gate-source voltage VGS of the switching element Q2 when both the DC power supply E2 are turned on.
FIG. 3 shows a characteristic diagram of the circuit efficiency η of the high-frequency power supply 3 with respect to the variable capacitor VC. 3, even if the value of the variable capacitor VC (or the voltage VGS between the gate and the source) changes, the circuit efficiency η maintains about 84%, and the capacitance value VC as in the conventional example is maintained.
There is no noticeable decrease in the circuit efficiency η near p. That is, even if the voltage applied to the primary winding n1 of the drive transformer T changes due to a change in the value of the variable capacitor VC, the circuit efficiency η does not change significantly.

Hereinafter, the point that the circuit efficiency η does not significantly change will be described. Here, comparing the gate-source voltage VGS waveforms of the switching element Q2 between the conventional example shown in FIG. 9 and the present embodiment shown in FIG. 2, the gate-source voltage VGS of the present embodiment shown in FIG. It can be seen that the waveform is distorted near zero V when rising from a negative potential. This is, as shown in FIG.
When the primary winding n22 and the secondary winding n22 are wound apart from each other, the magnetic coupling is weakened and such a waveform distortion occurs. However, even if the value of the variable capacitor VC changes, the waveform distortion acts. Therefore, it is considered that the ON width and the dead-off time of the switching elements Q1 and Q2 do not largely change. Therefore, in view of the fact that there is a correlation between the dead-off time and the loss in the switching elements Q1 and Q2, the voltage applied to the primary winding n1 of the drive transformer T changes due to the change in the value of the variable capacitor VC. The circuit efficiency η does not change significantly,
it is conceivable that.

(Embodiment 2) FIG. 4 is a schematic perspective view of a second embodiment according to the present invention.

The difference from the first embodiment shown in FIG. 1 is that the secondary windings n21 and n22 are wound close to each other and in a non-contact manner.
The same components as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

Next, the operation will be briefly described. DC power supply E
FIG. 5 shows a characteristic diagram of the circuit efficiency η with respect to the variable condenser VC when both the DC power supply 1 and the DC power supply E2 are turned on. As compared with the first embodiment shown in FIG. 3, the circuit efficiency η slightly decreases near the capacitance value VCp (= minimum value about 82%).
However, as compared with the conventional example shown in FIG. 10, the decrease in the circuit efficiency η is small. This is because the secondary windings n21 and n22
Are closer to each other, the distortion of the gate-source voltage VGS waveform is reduced, and accordingly, compared to the first embodiment, the switching element Q1 and the switching element Q1 for the value of the variable capacitor VC or the gate-source voltage VGS are reduced. It is considered that the change of the ON width of Q2 became large.

(Embodiment 3) A third embodiment according to the present invention will be described below.

In this embodiment, the primary winding n1 in the first and second embodiments is wound at a high density so that the area occupied by the winding with respect to the toroidal core 10 is minimized. . Since the leakage of magnetic flux in the primary winding n1 can be reduced by winding the primary winding n1 at a high density, power can be efficiently transmitted to the secondary windings n21 and n22.
In particular, when the electrodeless discharge lamp 1 is used as a load, a large amount of high-frequency power must be supplied to the high-frequency power supply coil 2 when the electrodeless discharge lamp 1 is started. By winding, the output of the preamplifier 6 can be efficiently transmitted to the main amplifier 7, so that the startability of the electrodeless discharge lamp 1 is improved.

(Embodiment 4) A fourth embodiment according to the present invention will be described below.

This embodiment is different from the first and second embodiments in that the primary winding n1 and the secondary winding n21 or the secondary winding n2 around the center of the toroidal core 10 as an axis.
2 are arranged substantially symmetrically to each other, so that the primary winding n1 and the secondary winding n21 or the secondary winding n
22 is at a maximum.

As described above, the primary winding n1 and the secondary winding n21
Alternatively, by maximizing the distance to at least one of the secondary windings n22, the parasitic capacitance generated therebetween is reduced, and the primary winding n1 and the secondary winding n
21 or at least one of the secondary windings n22, the switching element Q
1. The increase in switching loss in Q2 is also suppressed.

In all of the above embodiments, the gate-source voltage VGS is set to the gate-source voltage of the switching element Q2, but may be set to the gate-source voltage of the switching element Q1. Further, other magnetic cores may be used instead of the toroidal cores.
For example, it may be a carbonyl iron-based core or a Ni-Zn-based ferrite core.

[0037]

According to the first aspect of the present invention, even if the voltage applied to the primary side of the drive transformer changes due to a change in the characteristics of the components, etc., the power supply device can reduce the rate of change of the circuit efficiency η. Can be provided at low cost.

According to the second to fifth aspects of the present invention, in addition to the effects of the first aspect of the present invention, the voltage applied to the primary side of the drive transformer due to the time-dependent change in the characteristics of the components and the like. Even if the power supply voltage slightly changes, the dead-off time of the switching element hardly changes, so that the circuit efficiency does not significantly change and a power supply device capable of maintaining high circuit efficiency can be provided.

According to the invention of claim 6, in addition to the effects of the invention of claims 1 to 5, the parasitic capacitance generated between the primary and secondary windings of the drive transformer is reduced, It is possible to provide a power supply device capable of reducing switching loss caused by mutual induction current between the primary and secondary windings via a capacitor.

According to the seventh aspect of the invention, in addition to the effects of the first to sixth aspects, the output of the preamplifier can be efficiently transmitted to the main amplifier. A power supply device capable of improving the startability of an electric lamp can be provided.

According to the eighth aspect of the present invention, in addition to the effects of the first to seventh aspects of the present invention, unnecessary radiation noise can be reduced by using a toroidal core as the magnetic core because the leakage of magnetic flux is small. A power supply device that can be reduced can be provided.

According to the ninth aspect of the invention, in addition to the effects of the first to eighth aspects, the use of a carbonyl iron-based core as the magnetic core stabilizes the temperature characteristics and the magnetic flux level. , Good frequency characteristics.
A power supply device capable of exhibiting a high Q characteristic in a range of from 05 MHz to 200 MHz can be provided.

According to the tenth aspect, the first aspect is provided.
In addition to the effects of the invention described in claim 8, by using a Ni-Zn ferrite core as the magnetic core,
It is possible to provide a power supply device having a small loss (tan δ / μi), good frequency characteristics, and capable of exhibiting a high Q characteristic particularly at 0.5 MHz to 100 MHz.

According to the eleventh aspect of the present invention, the first aspect is provided.
In addition to the effects of the invention described above, by separately driving the switching element, a power supply device capable of performing a stable switching operation even when the operating frequency exceeds 10 MHz with an electrodeless discharge lamp as a load, for example, is provided. it can.

According to the twelfth aspect of the present invention, the first aspect of the present invention is as follows.
In addition to the effects of the described invention, it is possible to provide a power supply device capable of further reducing the loss in the switching element and improving the circuit efficiency.

According to the thirteenth and fourteenth aspects of the invention, in addition to the effects of the first aspect, there is provided a power supply device capable of efficiently lighting an electrodeless discharge lamp with high-frequency power. it can.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a first embodiment according to the present invention.

FIG. 2 shows a switching element Q according to the embodiment when both the DC power supply E1 and the DC power supply E2 are turned on.
2 shows a gate-source voltage VGS 2 waveform.

FIG. 3 is a characteristic diagram of the circuit efficiency η of the high-frequency power supply 3 with respect to the variable capacitor VC when both the DC power supply E1 and the DC power supply E2 are turned on according to the embodiment.

FIG. 4 is a schematic perspective view of a second embodiment according to the present invention.

FIG. 5 is a characteristic diagram of the circuit efficiency η with respect to the variable capacitor VC when both the DC power supply E1 and the DC power supply E2 are turned on according to the embodiment.

FIG. 6 shows a circuit diagram according to the invention.

FIG. 7 shows a schematic perspective view of a conventional example according to the present invention.

FIG. 8 shows a characteristic diagram of an amplitude change of the gate-source voltage VGS when the variable capacitor VC is changed when only the DC power supply E2 is turned on according to the conventional example.

FIG. 9 shows a waveform diagram of the gate-source voltage VGS of the switching element Q2 when both the DC power supply E1 and the DC power supply E2 are turned on according to the above-described conventional example.

FIG. 10 is a characteristic diagram of the circuit efficiency η with respect to the variable capacitor VC when both the DC power supply E1 and the DC power supply E2 are turned on according to the above conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electrodeless discharge lamp 3 high frequency power supply 9 drive device n1 primary winding n2 secondary winding Q switching element T drive transformer VGS control voltage

Claims (14)

[Claims] 1. A high-frequency power supply having two switching elements connected in series, converting a DC voltage into an AC high-frequency voltage and supplying it to a load, and controlling a primary winding and each of the two switching elements. A drive transformer having two secondary windings connected in series to a terminal, a primary winding, and a magnetic core wound with the two secondary windings, and applying a voltage to the primary winding of the drive transformer. And a drive device for driving the two switching elements, wherein the secondary winding is wound in a direction to reduce the on-time of the switching element and secure the on-time. apparatus. 2. The power supply device according to claim 1, wherein the two secondary windings are wound at equal intervals every turn. 3. The power supply device according to claim 1, wherein the two secondary windings are wound at equal intervals between all the secondary windings. 4. The power supply device according to claim 1, wherein the two secondary windings are wound in a non-contact manner. 5. The power supply device according to claim 1, wherein the two secondary windings are paired and bifilar wound. 6. The drive transformer according to claim 1, wherein the drive transformer is formed by winding the primary winding and the secondary winding in directions away from each other. Power supply. 7. The power supply device according to claim 1, wherein the primary winding is wound closely at each turn at least on an inner surface side of the magnetic core. 8. The power supply device according to claim 1, wherein the magnetic core is a toroidal core. 9. The power supply device according to claim 1, wherein the magnetic core is a carbonyl iron-based core. 10. The magnetic core according to claim 1, wherein the magnetic core is a Ni—Zn ferrite core.
The power supply device according to any one of the above. 11. The power supply device according to claim 1, wherein the drive device separately drives the switching element. 12. The power supply according to claim 1, wherein the high-frequency power supply is a class D amplifier circuit. 13. The operating frequency of the high-frequency power supply is 0.1.
13. The power supply according to claim 1, wherein the power supply is 5 MHz or more. 14. The power supply device according to claim 1, wherein the load includes at least an electrodeless discharge lamp.