JP3230560B2 - DC 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 DC power supply for rectifying a sine wave AC voltage such as a commercial AC voltage to obtain a DC voltage, and more particularly to a DC power supply capable of improving a power factor. .

[0002]

2. Description of the Related Art A typical DC power supply device is constructed by connecting a smoothing capacitor between output terminals of a diode bridge type full-wave rectifier circuit.

[0003]

In the above-described DC power supply device, the input AC current flows only at and near the peak value of the sine wave AC voltage, so that the power factor is reduced. In order to solve this kind of problem, a reactor (choke coil) may be connected between a rectifier circuit and a capacitor to form a choke input type filter circuit. However, this circuit has a drawback that a voltage drop occurs due to the resistance of the reactor according to the magnitude of the load current, and the output voltage decreases. In order to improve the power factor, a switching element is connected to the output stage of the rectifier circuit via a reactor, and the input element waveform is approximated to a sine wave by intermittently switching the switching element at a frequency higher than the AC power supply voltage. There is a scheme, but this scheme has the disadvantage of being expensive.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a DC power supply capable of improving a power factor with a relatively simple circuit configuration in which a change in output voltage due to a change in load current is small.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a full-wave rectifier circuit connected to a sine-wave AC power supply, and an output terminal between one output terminal and the other output terminal of the rectifier circuit. A DC power supply for supplying power to a load connected in parallel to the smoothing capacitor, the smoothing capacitor having one of an output terminal of the rectifier circuit and the smoothing capacitor. Connected to one end of the rectifier circuit, and formed so that a frequency signal higher than the frequency of the voltage of the AC power supply is superimposed on the output voltage of the rectifier circuit, and the amplitude of the frequency signal is proportional to the current flowing through the load. And a reactor connected in series to the frequency signal superimposing circuit between one output terminal of the rectifier circuit and the smoothing capacitor. It is intended according to the DC power supply device according to claim which has an inductance contained in Le or said frequency signal superimposing circuit. Claim 2
It is desirable to superimpose the frequency signal using a transformer as shown in FIGS. Claims 5 to 10, 12,
13, 13 to 19, when a resonance type switching regulator is included, a bias voltage can be obtained based on a frequency signal obtained by utilizing the resonance of the switching regulator. It is desirable to provide an auxiliary capacitor as described in claims 4, 11 and 14. Further, a DC bias voltage can be superimposed as described in claims 21 and 22. Further, a series resonance circuit for bias can be connected in parallel to the resonance capacitor. Claims 15 and 2
As shown by 0, a resonance capacitor can be connected in parallel with the secondary winding for bias voltage or the reactor.

[0006]

According to the invention, the power factor can be improved by suppressing the fluctuation of the output voltage. According to the fifth to twentieth aspects of the present invention, since the bias voltage is obtained based on the resonance signal, power factor improvement and voltage adjustment can be performed with a simple circuit. Claims 4 and 11
According to the fourteenth aspect, the ripple (high-frequency vibration) of the current can be reduced. According to the invention of claims 15 and 20, it is possible to suppress an increase in the voltage of the smoothing capacitor at a light load.

[0007]

First Embodiment Next, a DC power supply according to a first embodiment will be described with reference to FIGS. The DC power supply shown in FIG. 1 has an AC power supply terminal 1 to which a commercial AC power supply 1 is connected.
a, 1b, and a full-wave rectifier circuit 2 including a diode bridge circuit connected to the pair of power terminals 1a, 1b;
In addition to a reactor (choke coil) 3 as a smoothing inductance circuit element and a smoothing capacitor 4, a frequency signal superimposing circuit 5, that is, a bias voltage superimposing circuit is provided. The smoothing capacitor 4 is connected between one output terminal and the other output terminal of the rectifier circuit 2 via the reactor 3 and the frequency signal superimposing circuit 5. The load 6 is connected between a pair of output terminals 7 and 8 connected to one end and the other end of the capacitor 4. A resistor 9 as a current detector is connected to the load 6 in series.

The frequency signal superposition circuit 5 includes an oscillator 10,
Transformer 11 and transistor 1 as amplitude control element
2 The oscillator 10 generates a frequency signal having a repetition frequency (for example, 20 kHz) sufficiently higher than the frequency of the commercial AC power supply voltage as shown in FIG. An output terminal of the oscillator 10 is connected to a primary winding 13 of a transformer 11. Secondary winding 14 of transformer 11
Is electromagnetically coupled to the primary winding 13 and is connected between one output terminal of the rectifier circuit 2 and the reactor 3. Transistor 12 is connected between DC power supply terminal 15 and the power supply terminal of oscillator 10, and applies a voltage proportional to the detection voltage of current detection resistor 9 to the power supply terminal of oscillator 10. As a result, a frequency signal having an amplitude proportional to the current of the load 6 is obtained from the oscillator 10. In the present application, the above
Repetition frequency sufficiently higher than the frequency of the commercial AC power supply voltage
A signal having a number will be simply referred to as a frequency signal.

FIG. 2 schematically shows the state of each part in FIG.
When the commercial AC voltage is rectified by the rectifier circuit 2, a full-wave rectified voltage Vin shown in FIG. 2A is obtained between the output terminals.
The secondary winding 14 of the transformer 11 obtains the frequency signal Va shown in FIG. Rectified voltage Vin
The voltage Vb obtained by superimposing the frequency signal Va on the input voltage Vb becomes the voltage on the input side of the reactor 3 as shown in FIG. Assuming that the capacitor 4 has already been charged, this voltage Vc changes as shown by the dotted line in FIG. Reactor 3
When the input side voltage Vb becomes higher than the capacitor voltage Vc, the current Iin as shown schematically in FIG.
Flows. Even if the frequency signal superimposed voltage Vb intermittently crosses the capacitor voltage Vc, the current Iin continuously flows based on the release of the energy stored in the reactor 3.
The period during which the current Iin flows as shown in FIG.
, The power factor is improved.

When the current flowing through the load 6 in the circuit of FIG. 1 increases, for example, the voltage drop in the transistor 12 decreases, and the power supply voltage of the oscillator 10 increases.
The maximum amplitude Vm of the frequency signal Va shown in FIG. This makes it possible to increase the capacitor voltage Vc, thereby preventing the voltage Vc of the capacitor 4 from decreasing when the load current increases, which is a drawback of the choke input type smoothing circuit. Since the reactor 3 includes not only an inductance component but also a resistance component, when the load current increases, the voltage drop here increases, and the capacitor voltage Vc decreases.

[0011]

Second Embodiment Next, a DC power supply according to a second embodiment will be described with reference to FIGS. However, in FIG. 3 and FIGS. 7 to 20 to be described later, the same reference numerals are given to the portions common to FIG. 1 or to each other, and the description thereof will be omitted. The DC power supply device of FIG. 3 is configured such that the load 6 of FIG. 1 is a resonance type switching regulator 20 and the frequency signal superimposing circuit, that is, the bias voltage superimposing circuit 5 a utilizes the resonance of the switching regulator 20.

The switching regulator 20 is an insulated gate field effect transistor (hereinafter simply referred to as a transistor) as first and second switching elements connected between a pair of output terminals 7 and 8 of the smoothing capacitor 4. A) a series circuit of Q1 and Q2, an output transformer T1, and a resonance capacitor C1 connected in series to a primary winding N1 having a leakage inductance of the output transformer T1;
An auxiliary capacitor Cb connected in parallel to the second transistor Q2; first and second clamping diodes D1 and D2 connected in reverse direction to the first and second transistors Q1 and Q2; The second transistor Q1,
Control circuit 21 connected to the gate (control terminal) of Q2
And the secondary windings N2a and N2b of the output transformer T1,
The rectifying and smoothing circuit includes diodes D3 and D4 connected to the next windings N2a and N2b and a smoothing capacitor C0, an error amplifier 22, and a reference voltage source 23. The transformer T1 has an exciting inductance and a leakage inductance as is well known. Since the first and second transistors Q1 and Q2 have a structure in which the sources are connected to a substrate (bulk), the first and second diodes D1 and D2 are built in the transistors Q1 and Q2. Further, an auxiliary capacitor Ca can be connected in parallel with the first transistor Q1 as shown by a dotted line.

The series circuit of the primary winding N1 and the resonance capacitor C1 is connected in parallel to the second transistor Q2. Primary winding N1 and secondary windings N2a, N of transformer T1
2b is electromagnetically coupled via a core 9. Secondary winding N
Both ends of 2a and N2b are connected to one end of a capacitor C0 via diodes D3 and D4, and the center tap is connected to the other end of the capacitor C0. A load 25 is connected to an output terminal 24 connected to the smoothing capacitor C0. One input terminal of the error amplifier 22 is connected to the output terminal 24, the other input terminal is connected to the reference voltage source 23, and the error output line 26 is connected to the control circuit 21.
This error amplifier 22 outputs a voltage corresponding to the difference between the output detection voltage and the reference voltage.

The control circuit 21 is a VCO (Voltage Controlled Oscillator) whose output frequency is changed by being controlled by the voltage of the line 26.
A waveform shaping circuit for shaping the output waveform of the VCO;
7 (A) and 7 (B).
The signals Vg1 and Vg2 shown in FIG. FIG.
The first and second control signals Vg1 and Vg2 of (A) and (B) are alternately generated with a slight dead time and applied to the gates of the first and second transistors Q1 and Q2.

The first and second transistors Q1 and Q2 shown in FIG.
The control signal V shown in FIGS. 7A and 7B is applied to the gate of Q2.
When g1 and Vg2 are applied, the auxiliary capacitor Cb is charged by a circuit including the primary winding N1, the resonance capacitor C1 and the auxiliary capacitor Cb during the period from t0 to t1. t
When charging of the auxiliary capacitor Cb is completed at one point, the primary winding N1 having leakage inductance and the capacitor C1
The current flowing through the series circuit with
And a current flows through the series circuit and the closed circuit of the diode D1 and the capacitor 4. Therefore, the current I1 of the first switch circuit composed of the first transistor Q1 and the diode D1 becomes a reverse current from t to t2 as shown in FIG. The primary winding N1 has a leakage inductance L in series with the resistance component R1 of the winding as shown in FIG.
1 and a parallel exciting inductance Lp.

When the reverse current becomes zero at time t2, a closed circuit composed of the first transistor Q1, the leakage inductance L1 of the primary winding N1 having inductance, and the resonance capacitor C1 is next shown in FIG. ), A sinusoidal series resonance current flows as shown from t2 to t3. During the ON period of the first transistor Q1, in addition to the high frequency series resonance of C1 and the leakage inductance L1, the transformer T
A low frequency resonance also occurs due to the excitation inductance Lp of 1 and the capacitor C1. When the exciting inductance Lp is sufficiently larger than the leakage inductance L1, the resonance frequency based on the exciting inductance Lp becomes extremely low, and the current flowing through the exciting inductance Lp increases almost linearly with a slope. The current I1 flowing through the first transistor Q1 is a combination of the resonance current based on the leakage inductance L1 and the resonance current based on the excitation inductance Lp. T3 after the resonance current based on the leakage inductance L1 becomes zero at t3 in FIG.
From t4 to t4, the current based on the exciting inductance Lp becomes the current I1 of the first switch circuit.

When the first transistor Q1 is turned off at t4, the auxiliary capacitor Cb and the inductor 1 having an inductance are turned off.
A current Icb flows through a closed circuit composed of the next winding N1 and the resonance capacitor C1 as shown at t4 to t5 in FIG. 7 (G). That is, the current flowing through the exciting inductance Lp is diverted to the current Icb of the auxiliary capacitor Cb, and the auxiliary capacitor Cb is discharged. As a result, the voltage of the auxiliary capacitor Cb, that is, the drain-source voltage Vds2 of the second transistor Q2 gradually decreases as shown in FIG.
On the other hand, the drain-source voltage Vds1 of the first transistor Q1 becomes a value obtained by subtracting the drain-source voltage Vds2 of the second transistor Q2 from the voltage of the capacitor 4, as shown in FIG. Gradually higher,
Zero volt switching at turn-off is achieved.
When the control signal Vg2 of the second transistor Q2 is applied at time t5 as shown in FIG. 7B, the zero volt switching at the time of turning off is achieved. Therefore, the switching loss is significantly reduced.

When the voltage of the auxiliary capacitor Cb becomes substantially zero at time t5, the reverse bias of the second diode D2 is released. As a result, the excitation inductance Lp
Is supplied to the second diode D from the auxiliary capacitor Cb.
2 and the current flows during the period from t5 to t6 in FIG. That is, during the period from t5 to t6, a current flows through a closed circuit composed of the primary winding N1 having inductance, the series resonance capacitor C1 and the second diode D2. Also, t
During the ON period of the second transistor Q2 from 5 to t7, the second
A series resonance current flows in a closed circuit including the transistor Q2, the primary winding N1, and the series resonance capacitor C1. At this time, the current I2 flowing through the second switch circuit composed of the second transistor Q2 and the diode D2 is as shown in FIG.
Flows from time t5 to time t7, and is substantially the same as the current I1 of the first switch circuit shown in FIG.

When the second transistor Q2 is turned off at t7, the current I2 flowing downward due to the exciting inductance Lp is commutated to the auxiliary capacitor Cb.
The current Icb from t7 to t8 in (G) flows, and the capacitor Cb
, That is, the drain-source voltage Vds2 of the second transistor Q2 gradually increases as shown in FIG. On the other hand, since the drain-source voltage Vds1 of the first transistor Q1 is a value obtained by subtracting Vds2 from the voltage of the capacitor 4, it gradually decreases as shown in FIG. As a result, the first and second transistors Q1,
Zero volt switching of Q2 is achieved and switching losses are reduced.

At time t8, when the drain-source voltage Vds1 of the first transistor Q1 becomes substantially zero, the reverse bias of the first diode D1 is released, and the current of the exciting inductance Lp is removed from the auxiliary capacitor Cb by the first capacitor. And the current flows through the closed circuit of the primary winding N1, the first diode D1, the smoothing capacitor C0, and the series resonance capacitor C1.

When the voltage at the output terminal 24 becomes higher than a predetermined value in the apparatus shown in FIG.
Output frequency of the first and second transistors Q1, Q2 increases. Conversely, when the voltage at the output terminal 24 is lower than the predetermined value, the operation is opposite to the above.

The voltage V of the primary winding N1 of the output transformer T1
The amplitude of n1 varies depending on the on / off frequency f of the first and second transistors Q1, Q2. FIG. 5 shows the relationship between the on / off frequency f and the power P supplied to the secondary side of the transformer T1 by the resonance circuit of the leakage inductance L1 of the primary winding N1 and the capacitor C1. When the transistors Q1 and Q2 are turned on and off at a frequency higher than the inherent series resonance frequency f0 determined by L1 and C1, the supply power P
Decrease. FIG. 6 illustrates this.
When f shown in the first half of FIG. 6 is low, the amplitude of voltage Vn1 of primary winding N1 is large, but when f shown in the second half is high, the amplitude of voltage Vn1 decreases. As a result, voltage control and power control are achieved by controlling the on / off frequency f in the range of fa to fb.

The bias voltage superimposing circuit 5a of the DC power supply shown in FIG. 3 includes a primary winding of a bias voltage transformer 26 connected in parallel to a series resonance circuit of the primary winding N1 and the capacitor C1 in the switching regulator 20. 27
And a series circuit of a bias capacitor 28 and a bias voltage resonance capacitor 28. Since the primary winding 27 of the bias voltage transformer 26 has a leakage inductance similarly to the primary winding N1 of the output transformer T1, series resonance occurs between the leakage inductance and the capacitor 28, and the frequency is higher than that of the commercial AC power supply. A signal is obtained. The series resonance causes 1
The amplitude of the voltage obtained at the secondary winding 27 changes in proportion to the load current, similarly to the voltage amplitude of the series resonance caused by the leakage inductance L1 of the output transformer T1 and the capacitor C1.

Secondary winding 2 electromagnetically coupled to primary winding 27
Reference numeral 9 has a center tap, and this center tap is connected to one output terminal of the rectifier circuit. One end and the other end of the secondary winding 29 are connected to one end of the smoothing capacitor 4 via the first and second reactors 3a and 3b and the first and second bias diodes 30 and 31.

A frequency signal, that is, a bias voltage, obtained on the secondary winding 29 by resonance is superimposed on the output voltage of the rectifier circuit 2, and the same operation and effect as those of the DC power supply device of FIG. 1 can be obtained. Note that the DC power supply device of FIG. 3 does not require a special circuit for controlling the frequency signal, that is, the amplitude of the bias voltage according to the load current.
Cost reduction is achieved.

[0026]

Third Embodiment A DC power supply according to a third embodiment shown in FIG. 8 is such that the two reactors 3a and 3b shown in FIG. 3 are omitted, and the leakage inductance of the secondary winding 29 is increased instead. is there. Since the leakage inductance is connected in series equivalently to the secondary winding 29, the same operation and effect as in FIG. 3 can be obtained by FIG.

[0027]

Fourth Embodiment In the DC power supply of the embodiment of FIG. 9, the bias voltage primary winding 27 of the DC power supply of FIG. 3 is connected in parallel to the primary winding N1 of the output transformer T1. The configuration is the same as that of FIG. As described with reference to FIG. 6, the voltage of the primary winding N1 changes according to the load current.
7 changes in the same manner, and a frequency signal similar to that of FIG. Therefore, the device of FIG. 9 has the same operation and effect as the device of FIG. In FIG. 9, the reactors 3a and 3b can be omitted by providing the secondary winding 29 with a leakage inductance.

[0028]

Fifth Embodiment FIG. 10 omits the bias voltage primary winding 27 and the capacitor 28 of FIG. 8 and electromagnetically couples the bias voltage secondary winding 29 to the primary winding N1 of the output transformer T1. Has the same configuration as in FIG. This FIG.
In this case, a frequency signal corresponding to the primary winding N1 is obtained in the winding 29, and the same operation and effect as in FIG. In FIG. 10, instead of the leakage inductance of the winding 29, the reactors 3a and 3b can be connected in series to the diodes 30 and 31 as shown in FIG. Further, a common reactor can be connected between the cathodes of the diodes 30 and 31 and the smoothing capacitor 4.

[0029]

Sixth Embodiment The embodiment of FIG. 11 is a modification of the DC power supply of FIG. 8 so as to obtain a doubled voltage.
Instead of one smoothing capacitor 4, a series circuit of first and second smoothing capacitors 4a and 4b is provided. The tertiary winding 41 is connected to the bias voltage transformer 26.
Is added. The center tap of the tertiary winding 41 is the first
One end and the other end are connected to the series of the second smoothing capacitors 4a and 4b and the lower end of the circuit.
Is connected to the output terminal at the other end of the rectifier circuit 2. A switch 44 for selectively forming a voltage doubler circuit is connected between the lower AC power supply terminal 1b and a middle point of the interconnection between the first and second smoothing capacitors 4a and 4b.

Each of the secondary windings 29 and 41 has a leakage inductance. Therefore, the frequency signal superimposition effect can be obtained even in the circuit of FIG. When the switch 44 is turned off, a normal voltage (for example, 100 V) is obtained.
When the switch 44 is turned on, a double voltage (for example, 200
V) is obtained.

In FIG. 11, instead of having the secondary windings 29, 41 have a leakage inductance, the reactors 3a,
3b correspond to diodes 30, 31, respectively.
42 and 43 can be connected in series. Further, a common reactor can be connected between the diodes 30 and 31 and the capacitor 4, and a common reactor can be connected between the diodes 42 and 43 and the rectifier circuit 2.

[0032]

Seventh Embodiment A DC power supply apparatus shown in FIG. 12 is provided with a DC bias voltage superimposing circuit 5a instead of the frequency signal superimposing circuit 5 shown in FIG. DC bias voltage superposition circuit 5
a comprises a variable bias voltage source 50 and the control circuit 51. The variable bias voltage source 50 is connected in series between one output terminal of the rectifier circuit 2 and the reactor 3. This variable bias voltage source 50 can be composed of a capacitor or a storage battery. The control circuit 51 is formed so as to change the bias voltage in proportion to the load current detected by the current detection resistor 9.

When the current of the load 6 increases, the voltage drop due to the resistance of the reactor 3 increases, but the bias voltage supplied from the variable bias voltage source 50 also increases, so that the voltage drop due to the reactor 3 is compensated. The voltage change of the capacitor 4 can be suppressed.

[0034]

Eighth Embodiment The DC power supply shown in FIG. 13 is configured so that the load 6 shown in FIG. 12 is used as a switching regulator 20a, from which energy for the DC bias voltage superimposing circuit 5b is obtained.

FIG. 13 shows a switching regulator 20a.
Connects a series circuit of a primary winding 53 of an output transformer 52, a transistor 54 and a current detection resistor 9 between one end and the other end of the smoothing capacitor 4,
5 is connected to a rectifying / smoothing circuit of a diode 56 and a smoothing capacitor 57, and a control circuit 60 for keeping the voltage of output terminals 58 and 59 connected to the smoothing capacitor 57 constant.
Is provided. The load 61 is connected to the output terminal 58,
59. The control circuit 60 includes an error amplifier that forms an error signal between the reference voltage and the output voltage, a triangular wave generator, and a comparator that compares the triangular wave with the error signal to form a PWM pulse.
At a repetition frequency sufficiently higher than the frequency of the commercial AC power supply 1.

The DC bias voltage superimposing circuit 5b includes a bias winding 62 electromagnetically coupled to the primary and secondary windings 53 and 55 of the transformer 52, a reactor including one output terminal of the rectifier circuit 2 and a resistor. 3 includes a bias capacitor 63, diodes 64 and 65, a bias control transistor 66, and a control circuit 67.

The bias winding 62 is connected in parallel to a bias capacitor via a diode 64. The bias control transistor 66 is a diode 65
Are connected in parallel to the bias winding 62.
The control circuit 67 is connected between the current detection resistor 9 and the base of the transistor 66, and controls the primary winding 5 of the output transformer 52.
The transistor 66 is controlled so that the current flowing through the transistor 66 decreases when the current flowing through the transistor 3 increases.

The bias capacitor 63 is charged based on the voltage of the bias winding 62. The charging current of the bias capacitor 63 is controlled by the bias control transistor 66. When the load current, that is, the current flowing through the resistor 9, increases, the voltage of the bias capacitor 63 increases. Conversely, when the current of the resistor 9 decreases, the voltage of the bias capacitor 63 decreases. Therefore, the increase in the voltage drop in the reactor 3 due to the increase in the load current can be compensated for by the voltage of the bias capacitor 63, and the input voltage of the switching regulator 20a can be stabilized. Since the reactor 3 is provided, the power factor of AC input can be improved in the same manner as in another embodiment.

[0039]

Ninth Embodiment A DC power supply device shown in FIG. 14 has the same configuration as that of FIG. 1 except that an auxiliary diode Df and an auxiliary capacitor Cf are added to the circuit of FIG. The auxiliary diode Df is connected in series with the reactor 3, and the auxiliary capacitor Cf is connected in parallel with the series circuit of the primary winding 14, the reactor 3, and the auxiliary diode Df.
This auxiliary capacitor Cf contributes to removal of high-frequency components (ripple) of the current Iin, noise reduction, slight power factor improvement, and slight efficiency factor improvement.

[0040]

Tenth Embodiment A DC power supply device shown in FIG.
This circuit has the same configuration as that of FIG. 3 except that an auxiliary capacitor Df is added to the circuit of FIG. The auxiliary capacitor Cf includes a secondary winding 29, reactors 3a and 3b, diodes 30,
One series circuit is connected in parallel. That is, 2
It is connected between the center tap of the next winding 29 and the cathodes of the diodes 30, 31. The auxiliary capacitor Cf of FIG. 15 has the same operation and effect as that of FIG.

[0041]

Eleventh Embodiment The DC power supply shown in FIG.
10 except that an auxiliary capacitor Cf is added to the circuit of FIG. FIG. 16 shows the auxiliary capacitor Cf
Are the center tap of the secondary winding 29 and the diodes 30, 31.
And has the same function and effect as that of FIG. 8, 9 and 11, the auxiliary capacitor Cf is connected to the secondary winding 29 in the same manner as in FIGS.
And the cathodes of the diodes 30 and 31 can be connected.

[0042]

Twelfth Embodiment In the DC power supply shown in FIG. 17, a series resonance circuit of a bias voltage primary winding 27 having an inductance and a bias voltage capacitor 28 is connected in parallel to the resonance capacitor C1. Otherwise, the configuration is the same as that of FIG. The voltage Vc1 of the resonance capacitor C1 changes in proportion to the current of the load 25, that is, the output current. Therefore, when the output current is small under a light load, the voltage applied to the series resonance circuit of the primary winding 27 and the capacitor 28 decreases, the voltage of the bias voltage secondary winding 29 also decreases, and the bias voltage also decreases. As a result, it is possible to suppress a rise in the voltage of the smoothing capacitor 4 at a light load. 8, 11, 15, and 18, the series resonant circuit of the bias voltage primary winding 27 and the capacitor 28 can be connected in parallel to the resonant capacitor C1.

[0043]

Thirteenth Embodiment The DC power supply device shown in FIG.
The auxiliary resonance capacitor Cx is added to the DC power supply of
Other parts are the same as those shown in FIG. The capacitor Cx is connected to the secondary winding 29 for bias voltage and the reactor 3
a and 3b are connected in parallel. This capacitor Cx resonates with the inductance of the secondary winding 29 and the reactors 3a and 3b to change the frequency-output voltage relationship of the transformer 26. That is, the relationship between the bias voltage that can be added by the transformer 29 and the on / off frequencies of the first and second transistors Q1 and Q2 is as shown in FIG.
The first and second transistors Q1 and Q2 are turned on and off in a region higher than the resonance frequency f0. If the capacitor Cx is not provided, the output voltage cannot be brought close to zero even if the first and second transistors Q1 and Q2 are turned on and off at a high frequency as shown by the dotted line in FIG. Therefore, the level of the bias voltage cannot be sufficiently reduced at light load, and the voltage of the capacitor C4 increases as shown by the dotted line in FIG. Condessa Cx
19, the impedance is reduced and the bias voltage at the output stage of the transformer 26 can be reduced in a high frequency region as shown by the solid line in FIG.
As shown by the solid line, the voltage of the smoothing capacitor 4 can be suppressed in the light load region. As a result, it is possible to lower the breakdown voltage of the smoothing electrolytic capacitor 4 and the transistors Q1 and Q2. 8, 9 and 1
In the circuits of FIGS. 0, 11, 15, and 16, the auxiliary resonance capacitor Cx can be connected as shown by the dotted line in the same manner as in FIG.

[0044]

[Modifications] The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible. (1) FIGS. 3, 8 to 11, 15, 16, 17,
In the circuit shown in FIG. 18, apart from the primary winding N1, L
A resonance inductance equivalent to 1 can be provided independently. (2) The secondary winding 14 shown in FIGS. 1 and 14 has a leakage inductance, and the reactor 3 can be omitted. (3) In FIGS. 3, 9, 15, 17, and 18, a diode 3 is used instead of the two reactors 3a and 3b.
One common reactor can be provided between 0 and 31 and the capacitor 4. (4) The transistors Q1 and Q2 can be bipolar transistors. (5) FIGS. 3, 8 to 11, 15, 16 to 18
13 is replaced with another known half-wave rectifier circuit, full-wave rectifier circuit, half-wave doubler rectifier circuit, full-wave doubler rectifier circuit, or the like. be able to. (6) In each embodiment, a high frequency component removing capacitor can be connected between a pair of input terminals or a pair of output terminals of the rectifier circuit 2. However, when the connection is made as shown in FIGS. 14 to 16, the capacitance of the capacitor Cf can be reduced. Further, the same capacitor Cf as shown in FIG. 15 can be similarly connected to the circuits of FIGS. 8, 9, 11, 17, and 18.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a DC power supply device according to a first embodiment of the present invention.

FIG. 2 is a waveform chart of each part in FIG.

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

FIG. 4 is an equivalent circuit diagram of the transformer primary winding of FIG. 3;

FIG. 5 is a diagram for explaining the relationship between the on / off frequencies of Q1 and Q2 in FIG. 3 and the transmission power to the secondary side.

FIG. 6 shows ON / OFF frequencies of Q1 and Q2 and primary winding N1.
FIG. 4 is a diagram showing a relationship with the voltage of FIG.

FIG. 7 is a waveform chart showing a state of each unit in FIG. 3;

FIG. 8 is a circuit diagram illustrating a DC power supply device according to a third embodiment.

FIG. 9 is a circuit diagram illustrating a DC power supply device according to a fourth embodiment.

FIG. 10 is a circuit diagram showing a DC power supply device according to a fifth embodiment.

FIG. 11 is a circuit diagram showing a DC power supply device according to a sixth embodiment.

FIG. 12 is a circuit diagram showing a DC power supply device according to a seventh embodiment.

FIG. 13 is a circuit diagram showing a DC power supply device according to an eighth embodiment.

FIG. 14 is a circuit diagram illustrating a DC power supply device according to a ninth embodiment.

FIG. 15 is a circuit diagram showing a DC power supply device according to a tenth embodiment.

FIG. 16 is a circuit diagram showing a DC power supply device according to an eleventh embodiment.

FIG. 17 is a circuit diagram showing a DC power supply device according to a twelfth embodiment.

FIG. 18 is a circuit diagram showing a DC power supply device according to a thirteenth embodiment.

19 is a frequency characteristic diagram of the bias circuit of FIG.

20 is a diagram showing a relationship between a voltage and a frequency of the smoothing capacitor in FIG.

[Explanation of symbols]

 2 Rectifier circuit 3 Reactor 4 Smoothing capacitor 5 Frequency signal superposition circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02M 7/217 G05F 1/70 H02M 3/335

Claims (22)

(57) [Claims] 1. A smoothing capacitor comprising: a full-wave rectifier circuit connected to a sine-wave AC power supply; and a smoothing capacitor connected between one output terminal and the other output terminal of the rectifier circuit. In a DC power supply device for supplying power to a load connected in parallel to a capacitor, the DC power supply device is connected between one output terminal of the rectifier circuit and one end of the smoothing capacitor, and detects a voltage of the AC power supply. A frequency signal superimposing circuit formed so that a frequency signal higher than the frequency is superimposed on the output voltage of the rectifier circuit, and an amplitude of the frequency signal is formed to change in proportion to a current flowing through the load; A reactor connected in series with the frequency signal superimposing circuit between one output terminal of the rectifier circuit and the smoothing capacitor or an input included in the frequency signal superimposing circuit. DC power supply apparatus characterized by and a reactance. 2. The frequency signal superposition circuit includes: a frequency signal source that generates a frequency signal higher than a frequency of a voltage of the AC power supply; a primary winding of a transformer connected to the frequency signal source; A secondary winding of a transformer electromagnetically coupled to a secondary winding and connected in series between the rectifier circuit and the smoothing capacitor; and for changing the amplitude of the frequency signal in proportion to the current of the load. 2. The DC power supply according to claim 1, further comprising an amplitude control unit. 3. The DC power supply according to claim 2, wherein the secondary winding of the transformer has a leakage inductance, and the reactor is omitted. 4. An auxiliary diode connected in series with said reactor or inductance, and a frequency signal superimposing circuit connected in parallel with a series circuit of said reactor or inductance and said auxiliary diode. 4. A DC power supply according to claim 1, further comprising an auxiliary capacitor. 5. A rectifier circuit connected to a sine wave AC power supply, a smoothing capacitor connected between one output terminal and the other output terminal of the rectifier circuit, and a rectifier circuit connected to the smoothing capacitor. A DC power supply device having a resonance type switching regulator and supplying power to a load from the switching regulator, wherein a primary winding for a bias voltage having an inductance connected in parallel to an LC series resonance circuit of the switching regulator. A series resonance circuit comprising: a bias voltage capacitor; and a series resonance circuit, which is electromagnetically coupled to the bias voltage primary winding, is connected between one output terminal of the rectifier circuit and one end of the smoothing capacitor, and has an inductance. And a bias voltage secondary winding. 6. A rectifier circuit connected to a sine wave AC power supply, a smoothing capacitor connected between one output terminal and the other output terminal of the rectifier circuit, and a rectifier circuit connected to the smoothing capacitor. A DC power supply device having a resonance type switching regulator and supplying power to a load from the switching regulator, wherein a primary winding for bias voltage is connected in parallel to a primary winding of an output transformer of the switching regulator. And a bias voltage secondary winding electromagnetically coupled to the bias voltage primary winding and connected between one output terminal of the rectifier circuit and one end of the smoothing capacitor and having an inductance. And a DC power supply device. 7. A rectifier circuit connected to a sine wave AC power supply, a smoothing capacitor connected between one output terminal and the other output terminal of the rectifier circuit, and a rectifier circuit connected to the smoothing capacitor. A DC power supply having a resonant switching regulator and supplying power to a load from the switching regulator, wherein the DC power supply is electromagnetically coupled to a primary winding of an output transformer of the switching regulator, and one output terminal of the rectifier circuit and A DC power supply device comprising a bias voltage secondary winding connected between one end of a smoothing capacitor and an inductance. 8. A rectifier circuit connected to a sine wave AC power supply, a smoothing capacitor connected between one output terminal and the other output terminal of the rectifier circuit, and a rectifier circuit connected to the smoothing capacitor. A DC power supply having a resonance type switching regulator and supplying power from the switching regulator to a load, comprising: a primary for bias voltage having an inductance connected in parallel to a capacitor of an LC series resonance circuit of the switching regulator. A series resonant circuit of a winding and a bias voltage capacitor; an electromagnetically coupled to the bias voltage primary winding and connected between one output terminal of the rectifier circuit and one end of the smoothing capacitor; And a secondary winding for bias voltage having the following. 9. The bias voltage primary winding has substantially no inductance or has an inductance smaller than a desired value, and a resonance inductance is connected in series with the bias voltage primary winding. 9. The DC power supply according to claim 5, wherein the DC power supply is connected. 10. The bias voltage secondary winding has substantially no inductance or an inductance smaller than a desired value, and a reactor is connected in series to the bias voltage secondary winding. The DC power supply according to claim 5, 6 or 7, or 8 or 9. 11. An auxiliary diode connected in series to said bias voltage secondary winding, and a series connection of said bias voltage secondary winding, said inductance or said reactor and said auxiliary diode. 11. The DC power supply according to claim 5, further comprising an auxiliary capacitor connected in parallel to the circuit. 12. The bias voltage secondary winding has a center tap, the center tap is connected to one output terminal of the rectifier circuit, and one end and the other end of the bias voltage secondary winding are connected to each other. The DC power supply device according to claim 5, wherein the DC power supply device is connected to one end of the smoothing capacitor via first and second bias diodes. 13. The bias voltage secondary winding has substantially no inductance or has an inductance smaller than a desired value, and is connected in series with the first and second bias diodes. 13. The DC power supply according to claim 12, wherein the first and second reactors are connected or a common reactor is connected in series to the first and second bias diodes. 14. The DC power supply according to claim 11, wherein an auxiliary capacitor is connected between one output terminal of the rectifier circuit and one end of the smoothing capacitor. 15. The apparatus according to claim 5, further comprising a resonance capacitor connected in parallel to said bias voltage secondary winding or said reactor.
The DC power supply device according to any one of the above. 16. A rectifier circuit connected to a sine wave AC power supply, and a series circuit of first and second smoothing capacitors connected between one output terminal and the other output terminal of the rectifier circuit. A series circuit of first and second switching elements connected between one end and the other end of the series circuit of the first and second smoothing capacitors; a primary winding having an inductance; An output transformer having a secondary winding electromagnetically coupled to the winding, a rectifying and smoothing circuit connected to the secondary winding, and the second switching element via the primary winding. A resonance capacitor connected in parallel; a control circuit for alternately turning on and off the first and second switching elements with a dead time; and a reverse circuit for the first and second switching elements. The first and the second connected in parallel And a secondary capacitor connected in parallel to the second switching element, wherein the inductance connected in parallel to the second switching element or the resonance capacitor is A series resonance circuit having a bias voltage primary winding and a bias voltage capacitor, and a center tap electromagnetically coupled to the bias voltage primary winding and connected to one output terminal of the rectifier circuit. A bias voltage secondary winding having an inductance; one end and the other end of the bias voltage secondary winding;
A first and a second bias diode connected between one end of a series circuit of a second smoothing capacitor and a second smoothing capacitor; and the first and second bias diodes are electromagnetically coupled to the bias voltage primary winding. A bias voltage tertiary winding having a center tap and an inductance connected to the other end of the series circuit of the smoothing capacitor; one end and the other end of the bias voltage tertiary winding; and the rectifier Third and fourth terminals connected between the other output terminal of the circuit;
And a bias diode. 17. A device for continuously or selectively connecting one terminal of the sine-wave AC power supply to a middle point of interconnection between the first and second smoothing capacitors. 17. The DC power supply according to claim 16, wherein: 18. The DC power supply device according to claim 16, wherein the secondary and tertiary windings for bias voltage have no inductance or have an inductance smaller than a desired value, and the first and second windings have an inductance smaller than a desired value. The first and second reactors are connected in series to the second bias diode, or a common reactor is connected between the first and second bias diodes and one end of the smoothing capacitor, In addition, the third is connected in series with the third and fourth bias diodes.
And a fourth reactor connected in series, or a common reactor connected between the third and fourth bias diodes and the other end of the rectifier circuit. . 19. The bias voltage primary winding has no inductance or has an inductance smaller than a desired value, and a resonance inductance is connected in series to the bias voltage primary winding. The direct-current power supply according to claim 14, 17 or 18, wherein: 20. The semiconductor device according to claim 16, further comprising another resonance capacitor connected in parallel to the bias voltage secondary winding or the reactor. A DC power supply as described. 21. A rectifier circuit connected to a sine wave AC power supply, and a smoothing capacitor connected between one output terminal and the other output terminal of the rectifier circuit. In a DC power supply for supplying power to a load connected in parallel, a DC bias voltage is connected between one output terminal of the rectifier circuit and one end of the capacitor, and a DC bias voltage is superimposed on an output voltage of the rectifier circuit. DC bias voltage superimposing circuit formed so that the level of the DC bias voltage changes in proportion to the current flowing to the load, between the DC bias voltage superimposing circuit and the capacitor A DC power supply device comprising: an impedance circuit element having an inductance and a resistance connected thereto. 22. A rectifier circuit connected to a sine-wave AC power supply; a smoothing capacitor connected between one output terminal and the other output terminal of the rectifier circuit; At least one for connecting and disconnecting the voltage of the smoothing capacitor.
A DC power supply device comprising: a switching power supply circuit having one switching element and an output transformer for outputting a voltage intermittent at the switching element; and one output terminal of the rectifier circuit and the smoothing circuit. is a reactor is connected between one end of the use capacitor, the DC bias capacitor between one output terminal of the rectifier circuit and the reactor is connected to charge based on the DC bias capacitor to the output transformer And a control means for setting a voltage of the DC bias capacitor to a voltage proportional to a value of a current flowing through the switching element or a value of a current flowing through a load of the switching power supply circuit.