JP2003102179A - Power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply circuit which operates at a high efficiency rate, without using complex means. SOLUTION: Serial circuits of switching elements Q1 and Q2 are connected to a dc supply E, and a high-frequency signal from a high-frequency oscillating circuit OSC is inputted to their control terminals. The output voltage of the circuit OSC is applied to a primary winding n1. Secondary windings n21 and n22 are connected so that connection polarities of the control terminal of the switching elements Q1 and Q2 become mutually reverse in polarities. A series circuit of a resonance circuit RS1 and a load circuit LD are connected in parallel with the switching element Q2, on the side of a negative pole of the dc supply E. A serial resonance circuit RS2 is connected to the secondary winding n21 in parallel, and a serial resonance circuit RS3 is connected to the secondary winding n22 in parallel. An output waveform of the circuit OSC is made substantially a sine wave, and the resonance frequencies of the serial resonance circuits RS2 and RS3 are set higher than the drive frequency of the circuit OSC.

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.

[0002]

2. Description of the Related Art As a conventional power supply device, JP-A-9-149649
There is one shown in the publication. In this power supply device, as shown in FIG. 7, a series circuit of two switching elements Q1 and Q2 is connected to a DC power supply E. Switching element Q
ON / OFF control of 1 and Q2 is performed by inputting a rectangular wave-shaped high frequency signal output from the high frequency oscillation circuit OSC to a control terminal via a transformer T. The transformer T includes two secondary windings n21 and n22, and the output voltage of the high frequency oscillation circuit OSC as a drive circuit is applied to the primary winding n1. The secondary windings n21 and n22 are connected to the switching element Q.
The connection terminals 1 and Q2 are connected to the control terminal so that the connection polarities thereof are opposite to each other. Therefore, according to the output of the high frequency oscillation circuit OSC, the switching elements Q1, Q
2 is alternately turned on and off.

Further, a series circuit of a series resonance circuit RS1 composed of an inductor L1 and a capacitor C1 and a load circuit LD is connected in parallel to the switching element Q2 on the negative side of the DC power source E.

Then, between the connection point between the secondary winding n21 of the transformer T and the control terminal of the switching element Q1 and the negative side of the DC power source E, a series as a high frequency component increasing element composed of an inductor L7 and a capacitor C9. As a high-frequency component increasing element composed of an inductor L8 and a capacitor C10, which is connected to the resonance circuit RS4, between the connection point between the secondary winding n22 of the transformer T and the control terminal of the switching element Q2 and the negative side of the DC power source E. Is connected to the series resonance circuit RS5. Here, the series resonance circuits RS4 and RS5 are set to have a high impedance with respect to the driving frequency and a low impedance with respect to the ringing frequency. The resonance frequency of the series resonance circuit RS1 is set to be substantially equal to the drive frequency of the high frequency oscillation circuit OSC. As a result, the switching elements Q1 and Q2 can be turned on / off in the state where the current is zero, and the switching loss can be reduced.

Therefore, the oscillating current generated by ringing is not input to the control terminals of the switching elements Q1 and Q2 by flowing in the series resonance circuits RS4 and RS5,
As a result, the increase of the oscillating voltage due to ringing can be suppressed, the switching loss can be reduced, and the reduction of the conversion efficiency of the power supply device can be suppressed.

Further, as a conventional power supply circuit, Japanese Patent Laid-Open No.
There is one shown in the 8-275554 publication. This power supply circuit shifts the drive voltage of the high-side and low-side switching elements to the negative side, narrows the on-time, increases the dead time, reduces switching loss, and operates with high efficiency. is there.

[0007]

[Problems to be Solved by the Invention] However, JP-A-9-14
In the power supply device shown in Japanese Patent No. 9649, a rectangular wave voltage is used as the output of the high frequency oscillation circuit OSC, and the following problems occur.

First, the rectangular wave voltage is composed of many harmonic components in addition to the fundamental frequency when the Fourier series expansion is performed. However, when the driving frequency becomes high, the rectangular wave voltage is input to the switching elements Q1 and Q2. Among the voltages, particularly for the harmonic component, the input capacitance parasitic on the switching elements Q1 and Q2 has a low impedance, and the harmonic component voltage does not contribute to the driving of the switching elements Q1 and Q2 and becomes a loss. However, there was a problem that the efficiency of.

Next, since the transformer T has a high impedance in a high frequency region due to its frequency characteristic, the harmonic component of the rectangular wave voltage is not transmitted to the secondary windings n21 and n22 of the transformer T but becomes a loss, and the transformer T is lost. There is a problem that the efficiency of the power supply device decreases as the temperature of the power supply increases.

Further, in the power supply circuit disclosed in Japanese Patent Laid-Open No. 8-275554, there is a problem that means for shifting the drive voltage to the negative side becomes complicated and the cost increases.

The present invention has been made in view of the above problems, and an object thereof is to provide a power supply circuit which operates with high efficiency without using complicated means.

[0012]

In order to solve the above problems, the present invention provides a DC power supply, a switching circuit connected between the output terminals of the DC power supply, a primary winding and an electromagnetic wave. A high frequency circuit having a transformer having a primary winding and a secondary winding for inputting an output of the coupled secondary winding to a control terminal of the switching circuit to control ON / OFF of the switching circuit, and to the primary winding. A power supply device having a drive circuit for inputting a signal and a load circuit to which a high frequency voltage from the high frequency circuit is applied, the high frequency component having a frequency component higher than a drive frequency of a signal output from the drive circuit. An increasing element is provided on the input terminal side of the switching circuit. As a result, the voltage waveform input to the switching circuit is distorted, and the time during which the switching circuit exceeds the threshold voltage, that is, the on time is shortened, and as a result, the dead time, which is the off time, is lengthened, and The loss can be reduced.

The switching circuit may be composed of two switching elements which are connected in series between the output terminals of the DC power supply and are alternately turned on and off.

A substantially sinusoidal signal may be used as the signal input to the primary winding.

The high frequency component increasing element may be connected between the control terminal of the switching element and one of the two output terminals.

The high frequency component increasing element may be connected between the control terminal of the switching element and the secondary winding.

Further, the high frequency component increasing element is the above-mentioned 1
It may be connected to the next winding in series or in parallel.

The high frequency component increasing element may include at least one of a capacitor and an inductor.

The high frequency component increasing element is a resonance circuit having a capacitor and an inductor, the drive frequency is an industrial frequency band, and the resonance frequency of the resonance circuit may be higher than the industrial frequency band. Therefore, noise countermeasures can be relaxed.

Further, even if a high frequency voltage from the high frequency circuit is applied to the load circuit via a resonance circuit having a capacitor and an inductor and the resonance frequency of the resonance circuit is set to be substantially equal to the drive frequency. Good, by this, the switching element can be turned on and off in the state of zero current, and the switching loss can be reduced.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) FIG.
2 is a circuit diagram showing a power supply device according to the embodiment of FIG. The basic configuration of the power supply device according to the present embodiment is similar to that of the power supply device shown in FIG. 7 as a conventional example, and portions having the same functions are designated by the same reference numerals and description thereof will be omitted. The power supply device according to the present embodiment is the power supply device shown in FIG. 7 as a conventional example, in which the connection point between the secondary windings n21 and n22 of the transformer T and the control terminals of the switching elements Q1 and Q2 and the negative electrode of the DC power supply E. Series resonance circuit RS respectively connected between
4 and RS5, a series resonance circuit RS2 as a high frequency component increasing element of an inductor L2 and a capacitor C2 is connected in parallel with the secondary winding n21, and an inductor L3 and an inductor L3 are connected in parallel with the secondary winding n22. The configuration is such that a series resonance circuit RS3 as a high frequency component increasing element is connected to the capacitor C3. Then, the output waveform of the high frequency oscillation circuit OSC is set to a substantially sine wave, the drive frequency of the high frequency oscillation circuit OSC is set to 13.56 MHz in the industrial frequency band (ISM band), and the resonance frequency of the series resonance circuits RS2 and RS3 is 13.56 MHz. It is set larger.

Although MOSFETs are shown as the switching elements Q1 and Q2 used in the present embodiment, the present invention is not limited to this and any switching element can be used. However, a bipolar transistor, an IGBT or the like can be applied.

The operation of this embodiment will be described below. When the switching elements Q1 and Q2 are turned on / off, the input capacitance seen from the gate terminals of the switching elements Q1 and Q2 as viewed from the load side changes transiently due to the Miller effect. Therefore, a transient current flows through the series resonance circuits RS2 and RS3 when the switching elements Q1 and Q2 are switched on / off. Then, this transient current is applied to the series resonance circuit RS2, R
An oscillating current conforms to the resonance frequency of S3, and due to the effect of this oscillating current, the voltage waveforms between the gate and source terminals of the switching elements Q1 and Q2 are slightly distorted, and frequency components other than the fundamental wave increase. .

For example, when the series resonance circuits RS2 and RS3 are not connected, the waveform 1 remains substantially sinusoidal as shown by the broken line in FIG. 2, but in the circuit diagram shown in FIG. As indicated by the solid line 2 in FIG. 2, the width of the voltage waveform is narrowed as in the waveform 2, and the ON time is shortened while the switching elements Q1 and Q2 exceed the threshold voltage Vth. As a result, the on times of the switching elements Q1 and Q2 are both shortened, so that these switching elements Q1 and Q2 are turned on.
The time during which both 1 and Q2 are off, that is, the dead time becomes longer, and the loss in the switching elements Q1 and Q2 can be reduced.

Further, by setting the drive frequency of the high frequency oscillation circuit OSC to the industrial frequency band, the influence of noise can be mitigated. In addition, the series resonance circuit RS2
By setting the resonance frequency of RS3 to be higher than 13.56 MHz, the loss in the series resonance circuits RS2 and RS3 can be reduced.

(Second Embodiment) FIG. 3 is a circuit diagram showing a power supply device according to a second embodiment. The power supply device according to the present embodiment is the power supply device shown in FIG. 1 as the first embodiment, in which the load circuit LD is composed of an electrodeless discharge lamp La and a matching circuit M.

The electrodeless discharge lamp La includes a bulb B filled with a discharge gas containing a rare gas and an induction coil Co electromagnetically coupled to the internal space of the bulb B.
A high-frequency electromagnetic field formed by applying a high-frequency current to o acts on the discharge gas in the internal space of the bulb B to excite the discharge gas to emit light.

The matching circuit M includes a capacitor C4 inserted between the series resonance circuit RS1 and the induction coil Co, a connection point between the series resonance circuit RS1 and the capacitor C4, and a negative side of the DC power supply E. And a capacitor C5 connected to.

When the electrodeless discharge lamp La is used, the driving frequency of the high frequency oscillation circuit OSC is several hundred kHz to several hundred MH.
Since z is very high, the loss in the switching elements Q1 and Q2 is likely to be relatively large, and effective efficiency improvement is achieved by increasing the dead time of the switching elements Q1 and Q2 as in the present embodiment. You can

(Third Embodiment) FIG. 4 is a circuit diagram showing a power supply device according to a third embodiment. The power supply device according to the present embodiment is different from the power supply device shown in FIG. 1 as the first embodiment in that the series resonance circuits RS1 and RS2 are replaced by an inductor L4 and a capacitor C6 between the gate and drain terminals of the switching element Q1. , And a series resonance circuit of an inductor L5 and a capacitor C7 is connected between the gate and drain terminals of the switching element Q2. The switching element Q1,
The resonance frequency of the series resonance circuit connected between the respective gate and drain terminals of Q2 is set higher than the drive frequency of the high frequency oscillation circuit OSC.

The operation of this embodiment will be described below. When each of the switching elements Q1 and Q2 is turned on, the inductor L4 and the capacitor C6 form a series resonance circuit as a high frequency component increasing element, or the inductor L5.
Since the series resonance circuit as a high frequency component increasing element of the capacitor C7 and the capacitor C7 is substantially connected in parallel to the secondary windings n21 and n22 of the transformer T, a current first flows to the series resonance circuit side and the capacitor C6 or Charge the capacitor C7.

Since the capacitor C6 or the capacitor C7 is charged first, the gate-source voltage of the switching elements Q1 and Q2 rises with a slight delay as shown by the waveform 3 of the solid line in FIG. High frequency components increase. As a result, the effective switching element Q
ON time of 1 and Q2 becomes short, switching element Q
The loss in 1 and Q2 can be reduced.

In this embodiment, the series resonance circuit of the inductor and the capacitor is connected between the gate and drain terminals of the switching elements Q1 and Q2, but the switching is similarly performed when only the capacitor is connected. The loss in the element can be reduced. However, the voltage between the gate and source terminals can be further distorted by inserting an inductor and positively resonating.

(Fourth Embodiment) FIG. 6 is a circuit diagram showing a power supply device according to a fourth embodiment. The power supply device according to the present embodiment is different from the power supply device shown in FIG. 1 as the first embodiment in that the series resonance circuits RS2 and RS3 are replaced by a high frequency oscillation circuit OSC and a primary winding n of a transformer T.
A parallel resonance circuit as a high frequency component increasing element composed of an inductor L6 and a capacitor C8 is connected between 1 and 1. Here, the resonance frequency of the parallel resonance circuit is set to be higher than the drive frequency of the high frequency oscillation circuit OSC.

In all of the above-mentioned embodiments, since the resonance circuit is provided on the secondary side of the transformer T, it is necessary to provide the same resonance circuit at two places of the switching elements Q1 and Q2. In the present embodiment, since the resonance circuit is provided on the primary side of the transformer T,
By providing only one resonance circuit, the same effects as those of all the above-described embodiments can be obtained.

In this embodiment, the parallel resonant circuit composed of the inductor L6 and the capacitor C8 is connected between the high frequency oscillator circuit OSC and the primary winding n1 of the transformer T. The present invention is not limited to this. For example, a series or parallel resonance circuit as a high frequency component increasing element composed of an inductor and a capacitor may be connected in parallel to the primary winding n1 of the transformer T, and the component constants of these components are set appropriately. If it is selected, the circuit can be made equivalent to the circuit shown in FIG. 6, and the same effect can be obtained.

Further, in all the above-mentioned embodiments, the signal from the high-frequency oscillator circuit is substantially limited to the signal, but the signal is not limited to this, and a rectangular wave signal is used to omit it. You may make it distort to a sine wave signal.

In addition, in all the above-mentioned embodiments, two switching elements are used.
The high frequency voltage may be generated by one switching element.

[0039]

According to the present invention, a DC power supply, a switching circuit connected between the output terminals of the DC power supply, and 1
A high-frequency circuit having a transformer having primary and secondary windings for inputting an output of a secondary winding electromagnetically coupled to the secondary winding to a control terminal of the switching circuit to control ON / OFF of the switching circuit; A power supply device having a drive circuit for inputting a signal to a primary winding and a load circuit to which a high-frequency voltage is applied from the high-frequency circuit, the frequency being higher than the drive frequency of the signal output from the drive circuit. Since the high frequency component increasing element having a component is provided on the input terminal side of the switching circuit, the voltage waveform input to the switching circuit is distorted, and the switching circuit exceeds the threshold voltage. The time, that is, the on time, can be shortened, and as a result, the dead time, which is the off time, can be lengthened and the loss in the switching circuit can be reduced. Without using a complicated means,
It was possible to provide a power supply circuit that operates with high efficiency.

Further, the high frequency component increasing element is a resonance circuit having a capacitor and an inductor, the driving frequency is an industrial frequency band, and the resonance frequency of the resonance circuit is set to be higher than the industrial frequency band. If so, measures against noise can be relaxed.

A high frequency voltage from the high frequency circuit is applied to the load circuit via a resonance circuit having a capacitor and an inductor so that the resonance frequency of the resonance circuit is set to be substantially equal to the drive frequency. if,
The switching element can be turned on and off when the current is zero, and the switching loss can be reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a power supply device according to a first embodiment.

FIG. 2 is a voltage waveform diagram between terminals of a switching element of the power supply device according to the first embodiment.

FIG. 3 is a circuit diagram showing a power supply device according to a second embodiment.

FIG. 4 is a circuit diagram showing a power supply device according to a third embodiment.

FIG. 5 is a terminal voltage waveform diagram of a switching element of a power supply device according to a third embodiment.

FIG. 6 is a circuit diagram showing a power supply device according to a fourth embodiment.

FIG. 7 is a circuit diagram showing a power supply device according to a conventional example.

[Explanation of symbols]

E DC power supply OSC high frequency oscillator LD load circuit T transformer n1 primary winding n21, n22 secondary winding Q1, Q2 switching element L1 to L8 inductors C1 to C10 capacitors RS1 to RS5 series resonance circuit 1-3 waveforms La electrodeless discharge lamp M matching circuit B valve Co induction coil

Continued front page    F-term (reference) 5H007 AA00 CA02 CB04 CB12 CB22                       DB03                 5H740 AA05 BA12 BB05 BB08 BC01                       BC02 HH05 KK03

Claims (9)

[Claims] 1. A direct current power supply, a switching circuit connected between output terminals of the direct current power supply, and an output of a secondary winding electromagnetically coupled to a primary winding are input to a control terminal of the switching circuit. A high-frequency circuit having a transformer having a primary winding and a secondary winding for on / off controlling the switching circuit, a drive circuit for inputting a signal to the primary winding, and a load to which a high-frequency voltage from the high-frequency circuit is applied. A high-frequency component increasing element having a frequency component higher than a drive frequency of a signal output from the drive circuit is provided on the input terminal side of the switching circuit. Power supply. 2. The power supply device according to claim 1, wherein the switching circuit is composed of two switching elements that are connected in series between the output terminals of the DC power supply and that are alternately turned on and off. 3. The power supply device according to claim 1, wherein the signal input to the primary winding is a substantially sine wave signal. 4. The high frequency component increasing element is connected between a control terminal of the switching element and one of two output terminals. The power supply device according to any one of 1. 5. The high frequency component increasing element is connected between a control terminal of the switching element and the secondary winding, according to claim 2 or 3. Power supply. 6. The power supply device according to claim 2, wherein the high frequency component increasing element is connected to the primary winding in series or in parallel. 7. The power supply device according to claim 4, wherein the high frequency component increasing element includes at least one of a capacitor and an inductor. 8. The high frequency component increasing element is a resonance circuit having a capacitor and an inductor, the drive frequency is an industrial frequency band, and the resonance frequency of the resonance circuit is set to be higher than the industrial frequency band. The power supply device according to any one of claims 1 to 6. 9. The high frequency voltage from the high frequency circuit comprises:
Applied to the load circuit via a resonance circuit having a capacitor and an inductor, the resonance frequency of the resonance circuit is
9. The power supply device according to claim 1, wherein the drive frequency is set to be substantially equal to the drive frequency.