JPH0884473A - Dc power supply - Google Patents

Abstract

PURPOSE: To lower the breakdown strength of a switch and capacitor by enhancing the efficiency of a switching power supply in which the power factor can be improved. CONSTITUTION: The DC power supply comprises a first and a second rectifier circuits. The first rectifier circuit 3 is connected in parallel with a smoothing capacitor 12 which is connected in parallel with a series circuit of the primary windings 7, 9 of first and second transformers 6, 8 and a switch 10. A reactor 4 is connected between the second rectifier circuit and the joint of the primary windings 7 and 9. Secondary windings 13, 14 of the first and second transformers 6, 8 are connected through diodes 15, 16 with an output smoothing capacitor 17. The two windings 13, 14 are formed with opposite polarities. This circuitry reduces the current flowing through the reactor 4 and thereby the efficiency is enhanced correspondingly.

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 device capable of improving power factor.

[0002]

2. Description of the Related Art When a DC power supply of a switching power supply is constructed by connecting a rectifying and smoothing circuit to a commercial AC power supply, a charging current flows through a smoothing capacitor only in the peak region of a sine wave AC voltage, and an input current waveform and force The rate gets worse. In order to solve this kind of problem, a power factor correction circuit may be provided in the preceding stage of the switching regulator circuit. However, if the power factor correction circuit and the switching regulator circuit are separately provided, the power supply device becomes large and costly.

In order to solve this kind of problem, it is conceivable to share the switch with the power factor correction and the switching regulator as shown in FIG. In the DC power supply device of FIG. 1, a bridge type rectifier circuit 3 including diodes D1, D2, D3 and D4 is connected to AC power supply terminals 1 and 2 to which a commercial AC power supply is connected via a high frequency filter (not shown). Is connected to this output terminal and common terminal (ground)
And a reactor (inductance circuit element) 4, a diode 5, a primary winding 7 of a first transformer 6, a primary winding 9 of a second transformer 8, and a switch 10 including a field effect transistor. Are connected. A diode 11 is connected between the output end of the reactor 4 and the upper end of the switch 10, and a smoothing capacitor 12 is connected between the cathode of the diode 5 and the lower terminal of the rectifier circuit 3. The secondary windings 13 and 14 of the first and second transformers 6 and 8 are the first and second output rectifying diodes 1 and 2.
It is connected to a common output smoothing capacitor 17 via 5 and 16. The first and second transformers 6 and 8 are formed to have polarities opposite to each other. In other words, the transformer 6, so that the diodes 15 and 16 operate opposite to each other,
8 and diodes 15 and 16 are connected. The pair of DC output terminals 18 and 19 are connected to both ends of the capacitor 17.

The switch 10 has a repetition frequency (for example, 20) higher than the frequency of the AC power supply terminals 1, 2 of, for example, 50 Hz.
The control circuit 20 for on / off operation at (kHz) is connected to the output terminals 18 and 19 as resistors 21 and 22 as voltage detecting means, and one input terminal is connected to the voltage dividing point of the resistors 21 and 22. The other input terminal is connected to the reference voltage source 23, the error amplifier 24, the triangular wave generator 25 that generates a triangular wave in the switching cycle, one input terminal is connected to the output of the error amplifier 24, and the other input is connected. The voltage comparator 26 has a terminal connected to the triangular wave generator 25 and an output terminal connected to the control terminal (gate) of the switch 10. The error amplifier 24 outputs a voltage corresponding to the difference between the detected voltage and the reference voltage, and the comparator 26 compares the triangular wave with the error output to form a PWM pulse, which is sent to the switch 10.

In the circuit of FIG. 1, while the switch 10 is on, a current flows through the circuit of the reactor 4, the diode 11 and the switch 10, and energy is accumulated in the reactor 4. During the off period of the switch 10, the diode 5 is turned on by the output voltage of the rectifier circuit 3 and the voltage (stored energy) of the reactor 4, and the capacitor 12 is charged.
When the switch 10 is turned on with the capacitor 12 being charged, the reactor 4, the diode 11 and the switch 1 are turned on.
A current flows in the reactor 4 in the circuit of 0, and a current also flows in the closed circuit of the capacitor 12, the primary windings 7 and 9 of the first and second transformers 6 and 8, and the closed circuit of the switch 10 while using the capacitor 12 as a DC power source. . At this time, since the voltage of the upward polarity is generated in the secondary winding 14 of the second transformer 8,
The second output rectifying diode 16 is turned on and the capacitor 17 is charged. On the other hand, since a downward voltage is generated in the secondary winding 13 of the first transformer 6, the first output rectifying diode 15 is kept off, and magnetic energy is stored in the first transformer 6. . During the off period of the switch 10 thereafter, as described above, the capacitor 1
2 is charged, the stored energy of the first transformer 6 is released, the first output rectifying diode 15 is turned on, and a charging current flows through the capacitor 17. Therefore, the output smoothing capacitor 17 is charged during both the ON period and the OFF period of the switch 10. Even if the primary-side capacitor 12 that functions as a DC power supply is charged to a voltage higher than the peak of the output voltage of the rectifier circuit 3 (about twice the power supply voltage) by the boosting action of the reactor 4, this capacitor 12 Voltage of the first and second transformers 6, 8
Since it is divided and applied to the primary windings 7 and 10 of
And the ratio of the primary and secondary turns of the second transformers 6 and 8 is 1:
In the case of the design of 1, the voltage of the output smoothing capacitor 17 does not become higher than the voltage of the primary side capacitor 12.

When the output voltage of the circuit of FIG. 1 becomes lower than the desired value, the duty ratio of the PWM wave becomes large and the ON time width of the switch 10 becomes long. On the contrary, when the output voltage becomes higher than the desired value, the duty ratio of the PWM wave becomes small and the ON time width of the switch 10 becomes short.

[0007]

By the way, in the circuit of FIG. 1, current flows through the reactor 4 during both the ON period and the OFF period of the switch 10. As a result, a power loss occurs due to the resistance of the reactor 4, and the effect deteriorates. Moreover, since the capacitor 12 is charged higher than the power supply voltage, an expensive capacitor having a high breakdown voltage is required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a DC power supply device which can be miniaturized, reduced in cost, improved in power factor, and improved in efficiency.

[0009]

SUMMARY OF THE INVENTION To achieve the above object, the present invention is directed to an AC power supply terminal and includes first and second
A rectification circuit having a rectification output terminal and a common terminal of
A capacitor connected between the first rectified output terminal and the common terminal; a primary winding of a first transformer and a first transformer of a second transformer connected in parallel to the capacitor;
Between a series circuit of a secondary winding and a switch, between the output terminal of the second rectifier circuit and the primary windings of the first and second transformers, or the primary winding of the first and second transformers. Between an inductance circuit element connected to any position of the wire, secondary windings of the first and second transformers, secondary winding of the first transformer and an output smoothing capacitor Is connected between the first output rectifying diode connected to the second transformer, the secondary winding of the second transformer and the output smoothing capacitor, and is turned on when the first rectifying diode is off. A second output rectifying diode having directionality for charging the output smoothing capacitor, and a control circuit for ON / OFF controlling the switch at a repetition frequency higher than the frequency of the AC voltage applied to the AC power supply terminal. DC power supply with It is those related to the location. As described in claim 2, first and second auxiliary diodes are connected between the inductance circuit element and the first and second positions (including interconnection points) of the two primary windings. be able to. In addition, as described in claim 3, the inductance circuit element and the first and second primary windings in the two primary windings.
An auxiliary capacitor and an auxiliary diode can be connected between and at the position (including the interconnection point). Further, as described in claim 4, it is possible to adopt a configuration in which only the primary winding of one transformer is connected to the switch. Also, in the DC power supply device having the structure of claim 4, the first and second auxiliary diodes are provided as shown in claim 5, and as shown in claim 6, the auxiliary capacitor and the auxiliary diode are provided. And can be provided. Further, as described in claim 7, a diode, a capacitor and a switch for performing a resonance operation can be provided.

[0010]

According to the invention of each claim, the capacitor in the input stage of the series circuit of the switch and the primary winding of the transformer does not substantially include the inductance circuit element (reactor), and the first rectification is performed. Connected to the output terminal.
Therefore, the current flowing through the inductance circuit element is reduced, the power loss here is reduced, and high efficiency is achieved. Moreover, since the charging voltage of the capacitor can be lowered, it is possible to achieve downsizing and cost reduction by using a capacitor with low breakdown voltage and low cost. Further, since the output smoothing capacitor is charged during both the ON period and the OFF period of the switch, it is possible to obtain an output with small ripple. According to the seventh aspect, it is possible to obtain the effect of reducing the switching loss due to resonance.

[0011]

[First Embodiment] Next, a DC power supply apparatus according to a first embodiment of the present invention will be described with reference to FIGS. However, FIG.
In FIG. 1, parts that are substantially the same as those in FIG. 1 are assigned the same reference numerals and explanations thereof are omitted. The DC power supply device of FIG. 2 is obtained by changing the connection position of the reactor (inductance circuit element) 4 of FIG. That is, in FIG. 2, the first rectifying circuit 3
The capacitor 12 is connected between the first rectified output terminal (output line) and the common terminal (ground line) of the device without a reactor, and the fifth and sixth diodes D5
, D6, and a second rectification output terminal (output line) and an interconnection point 28 between the primary windings 7 and 9 of the first and second transformers 6 and 8. Reactor 4 is connected between. The fifth and sixth diodes D5 and D6 are connected between the pair of AC power supply terminals 1 and 2 and the reactor 4. Therefore, a combination of the fifth and sixth diodes 27 of the second rectifier circuit 27 and the second and fourth diodes D2 and D4 of the first rectifier circuit 3 constitutes a bridge rectifier circuit. The second and fourth diodes D2 and D4 may not be shared by the first and second rectifier circuits 3 and 27, and the seventh and eighth diodes may be added for the second rectifier circuit 27. it can.

In the circuit of FIG. 2, since the reactor 4 is moved, there is nothing between the first rectifying circuit 3 and the capacitor 12 that corresponds to the reactor 4 and the diode 5 shown in FIG. The circuit of FIG. 2 also includes the diode 11 of FIG.
There is no equivalent to. In the circuit of FIG. 2, parts other than the reactor 4 and the second rectifier circuit 27 are configured the same as the circuit of FIG.

[0013]

[Operation] In the circuit of FIG. 2, when a commercial AC power supply (sine wave AC power supply) is connected to the AC power supply terminals 1 and 2 through a high-frequency filter (not shown), the first rectifier circuit 3 obtains the same. The rectified output voltage V1 of (A) charges the input smoothing capacitor 12, and the charged voltage is applied to the series circuit of the primary windings 7 and 9 of the first and second transformers 6 and 8 and the switch 10. . Control signal Vg shown in FIG.
Switch 10 on and off to output terminal 18,
When power is supplied to a load (not shown) connected to 19, the discharge of the capacitor 12 occurs, so that
While the rectified output voltage V1 is higher than the voltage Vc of the capacitor 12 shown by the dotted line in (A), a current I1 flows from the first rectifier circuit 3 to the capacitor 12 and the transformers 6 and 8 as shown in FIG. 3C. . The waveform of the current I1 in FIG. 3 (C) is shown schematically, ignoring fluctuations caused by turning the switch 10 on and off. If the reactor 4 is not provided, a current corresponding to the current I1 in FIG. 3C flows to the input side of the first rectifier circuit 3, so that the AC current has large waveform distortion and the power factor becomes low. .

During the ON period Ton of the switch 10, a current flows in a closed circuit composed of the capacitor 12, the two primary windings 7 and 9 and the switch 10, and at the same time, the power supply terminal 1 or 2, the diode D5 or D6 and the reactor. The current IL also flows in a closed circuit composed of the primary winding 9 of the second transformer 8, the switch 10, and the diode D2 or D4 as shown in FIG. 3 (D). It should be noted that sections Ta and Tb in which the potential applied to the interconnection point 28 between the two primary windings 7 and 9 based on the capacitor 12 is higher than the potential on the input end side of the reactor 4.
, Tc, Td, no current flows in the reactor 4. Since the secondary winding 13 of the first transformer 6 has a polarity that generates a downward voltage when the switch 10 is on, the diode 15 is kept off during the on period Ton. Therefore,
The first transformer 6 and the switch 10 are configured as a reverse type (flyback type) switching regulator, and magnetic energy is stored in the transformer during the on period Ton. On the other hand, the secondary winding 14 of the second transformer 8
Generates an upward voltage during the on period Ton, so that the diode 16 is turned on during the on period Ton. Therefore, the second transformer 8 and the switch 10 form a forward type switching regulator. In addition to the current based on the capacitor 12, the current IL of the reactor 4 also flows through the primary winding 9 of the second transformer 8. The current IL of the reactor 4 gradually increases during the ON period Ton of the switch 10 and gradually decreases during the OFF period Toff. In addition, it is desirable that the inductance of the reactor 4 be set to a size that allows all of the stored energy to be released during the off period Toff. The peak of the triangular wave of the current IL of the reactor 4 changes according to the magnitude of the output voltage of the second rectifier circuit 27. Therefore,
If a high frequency filter (not shown) is connected to the AC power supply terminals 1 and 2, this input current waveform approximates a sine wave. Since the sum of the current I1 of the first rectifier circuit 3 of FIG. 3C and the reactor current IL passing through the second rectifier circuit 27 of FIG. 3D flows through the AC power supply terminals 1 and 2, The closeness to the sine wave is worse than the case of only the reactor current IL in FIG. However, the sum current has a better approximation to the sine wave and a better power factor than the case of only the current I1 of the first rectifier circuit 3 in FIG. 3 (C). In addition,
FIG. 3E shows the waveform of the input current of the high-frequency filter (not shown) connected to the AC power supply terminals 1 and 2.

The reactor current IL in the off period Toff of the switch 10 is the reactor 4, the primary winding 7 of the first transformer 6, the capacitor 12, the diodes D2, D4 and D5.
, D6 and flows in a closed circuit. As a result, the capacitor 12 is charged by releasing the stored energy of the reactor 4. Further, since the reactor current IL flowing through the primary winding 7 in the off period T0ff generates an upward voltage in the secondary winding 13, it contributes to the charging of the output smoothing capacitor 17. In the off period Toff, a voltage equal to or more than twice the power supply voltage composed of the sum of the output voltage of the second rectifier circuit 27 and the voltage of the reactor 4 is generated at the output terminal of the reactor 4, which is the primary voltage. Since the voltage is divided by the winding 7 and the capacitor 12, almost the power supply voltage is applied to the capacitor 12.
Therefore, the voltage of the capacitor 12 in the circuit of FIG. 2 becomes almost the power supply voltage, which is almost half the voltage of the capacitor 12 in the circuit of FIG. Therefore, it is possible to reduce the withstand voltage of the capacitor 12 and achieve size reduction and cost reduction.

This embodiment has the following advantages. (1) A current for improving the power factor and improving the input current waveform flows through the reactor 4, and a current for charging the capacitor 12 does not flow so much. Therefore, the current of the reactor 4 is smaller than that of the circuit of FIG. 1, the power loss based on the resistance of the reactor 4 is reduced, and the efficiency can be improved. (2) Capacitor 1 despite including reactor 4
Since the voltage of 2 is almost the power supply voltage, it is possible to use a capacitor 12 having a low withstand voltage and a small size, and the cost and size of the device can be reduced. (3) Since the first and second transformers 6 and 8 have polarities opposite to each other, one of them is operated as a reverse switching regulator and the other is operated as a forward switching regulator, and both of the ON period and the OFF period of the switch 10 are operated. Since the output smoothing capacitor 17 can be charged, an output with less ripple can be obtained.

[0017]

[Second Embodiment] Next, a DC power supply device according to a second embodiment of the present invention will be described with reference to FIG. However, in FIG. 4, parts that are substantially the same as those in FIGS. 1 and 2 are given the same reference numerals, and descriptions thereof will be omitted. In FIG. 4, the output terminal of the reactor 4 is connected to the intermediate tap of the primary winding 7 of the first transformer 6, and the configuration is the same as that of FIG.

When the connection point of the reactor 4 is moved from the interconnection point 28 to the upper position as shown in FIG. 4, the amount of the primary windings 7 and 9 between the reactor 4 and the switch 10 is increased, so that the switch 10 is turned on. The current IL flowing in the reactor 4 during the ON period Ton becomes small, and the power loss due to the resistance here becomes small. Further, the time width of the sections Ta, Tb, Tc, and Td in which no current flows in the reactor 4 shown in FIG. 3D is longer than that of the circuit of FIG. 2, and the switching loss is reduced. Therefore, the efficiency of the circuit of FIG. 4 is higher than that of FIG. However, the effect of improving the sinusoidal approximation of the input current (improving the waveform) and the effect of improving the power factor by the reactor 4 are reduced.

The output end of the reactor 4 can be connected to an intermediate tap or an arbitrary position of the primary winding 9 of the second transformer 8 as shown by a dotted line in FIG. In this case, the amount of the primary winding 9 between the reactor 4 and the switch 10 is reduced, so that the current IL of the reactor 4 is increased, and the waveform improving effect and the power factor improving effect are increased. However, the efficiency is reduced. Therefore, the connection point of the reactor 4 is set at an arbitrary position of the primary windings 7 and 9 of the first and second transformers 6 and 8 according to the importance of improving the waveform, improving the power factor, and improving the efficiency. it can. The circuit shown in FIG. 4 basically has the same effects as the circuit shown in FIG.

[0020]

[Third Embodiment] Next, a DC power supply apparatus according to a third embodiment will be described with reference to FIG. However, in FIG. 5, parts that are substantially the same as those in FIGS. 1 and 2 are given the same reference numerals, and descriptions thereof will be omitted. The circuit of FIG. 5 is the same as that of FIG. 2 except that the first and second auxiliary diodes 31 and 32 are added to the circuit of FIG. The first auxiliary diode 31 is connected between the output terminal of the reactor 4 and the interconnection point 28 as the first position, and the second auxiliary diode 3 is connected.
2 is connected between the output end of the reactor 4 and the intermediate tap as the second position of the primary winding 9 of the second transformer 8.

The basic operation of the circuit of FIG. 5 is the same as that of the circuit of FIG. During the on period Ton of the switch 10, the second auxiliary diode 32 is turned on and the first auxiliary diode 31 is kept off due to the impedance. Therefore, the current IL of the reactor 4 is equal to the second auxiliary diode 3
2 and a part of the primary winding 9 and a switch 10.
Therefore, the number of turns of the primary winding 9 that works effectively decreases.
As a result, when the same voltage as in FIG. 2 is obtained in the secondary winding 14 of the second transformer 8, the number of turns of the secondary winding 14 can be made smaller than that in FIG. As a result, downsizing and cost reduction of the transformer 8 can be achieved.

In the period Toff in which the switch 10 is off in the circuit of FIG. 5, the current due to the release of the stored energy of the reactor 4 causes the current to flow between the first auxiliary diode 31 and the primary winding 7 of the first transformer 6. The energy flows through the circuit of the capacitor 12, the energy is released to the secondary winding 13 side, and the capacitor 1
Used to charge 2. The cathodes of the first and second auxiliary diodes 31 are connected to the first and second transformers 6 and 8 respectively.
Can be connected to the center tap or the upper end or the lower end of the primary windings 7, 9.

Since the circuit of FIG. 5 is basically the same as the circuit of FIG. 2, it has the same effects as the circuit of FIG.

[0024]

[Fourth Embodiment] Next, a DC power supply device according to a fourth embodiment will be described with reference to FIG. However, in FIG. 6, the substantially same parts as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted. The circuit of FIG. 6 has the same configuration as the circuit of FIG. 2 except that an auxiliary capacitor 41 and an auxiliary diode 42 are added to the circuit of FIG. The auxiliary capacitor 41 is connected between the output end of the reactor 4 and the interconnection point 28 as the first position of the two primary windings 7 and 9, and the auxiliary diode 42 is connected to the output end of the reactor 4 and the primary winding. Second on line 9
Connected between the middle tap as the position of.

The basic operation of the circuit of FIG. 6 is the same as that of FIGS. During the ON period Ton of the switch 10, the primary windings 7 and 9 of the transformers 6 and 8 are powered by the capacitor 12 as a power source.
Current flows through the circuit consisting of
An electric current also flows in a circuit including the reactor 4, the auxiliary diode 42, a part of the primary winding 9, and the switch 10. As a result, the voltage adjusting action, the waveform improving action, and the power factor improving action occur. Further, the primary winding 9 is provided during the ON period of the switch 10.
The voltage of a part of the upper side of the auxiliary capacitor 41 is rectified by the auxiliary diode 42 and applied to the auxiliary capacitor 41.
Is charged so that the right side of is positive. During the off period Toff of the switch 10, the stored energy of the reactor 4 and the stored energy of the auxiliary capacitor 41 are added to the rectified output, and the rectifier circuit 27, the reactor 4, and the auxiliary capacitor 41 are added.
A current flows through a circuit composed of the primary winding 7 of the first transformer 6, the capacitor 12 and the diode D2 or D4.
Power supply to the secondary side of the transformers 6 and 8 is performed in the same manner as the circuit of FIG. Therefore, the circuit of FIG. 6 has substantially the same effects as the circuit of FIG. In FIG. 6, the connection point at the right end of the auxiliary capacitor 41 is the primary winding 7 or 9
, And the auxiliary diode 42.
Can be connected to any position of the primary winding 7 or 9. Further, the connection positions of the auxiliary capacitor 41 and the auxiliary diode 42 can be interchanged, that is, reversed.

[0026]

[Fifth Embodiment] Next, a DC power supply device according to a fifth embodiment of the present invention will be described with reference to FIG. However, in FIG. 7, parts that are substantially the same as those in FIG. 2 are assigned the same reference numerals and explanations thereof are omitted. 2 except that the second transformer 8 and the diode 16 are omitted from the DC power supply device of FIG.
Is configured similarly to.

In FIG. 7, the output terminal of the reactor 4 is 1
Although it is connected to the terminal on the side of the secondary winding 7 and the switch 10, it can also be connected to any part of the primary winding 7 as shown by the dotted line.

Since the basic configuration of the circuit of FIG. 7 is the same as that of FIG. 2, the same working effect as that of the first embodiment can be obtained by the fifth embodiment.

[0029]

[Sixth Embodiment] A DC power supply apparatus according to a sixth embodiment shown in FIG. 8 will be described below. However, in FIG.
The same reference numerals are given to the substantially same portions as those, and the description thereof will be omitted. The circuit of FIG. 8 is obtained by omitting the second transformer 8 and the diode 16 from the circuit of FIG. 2 and providing the first and second auxiliary diodes 31 and 32 as in the case of FIG.
The auxiliary diodes 31 and 32 are the reactor 4 and the primary winding 7.
Connected between the first and second positions of. In addition,
The first and second positions can be changed arbitrarily.

Since the circuit of FIG. 8 is the same as the circuit of FIG. 5, it is possible to obtain the same effect as that of the circuit of FIG.

[0031]

[Seventh Embodiment] Next, a DC power supply device according to a seventh embodiment will be described with reference to FIG. However, in FIG. 9, parts that are substantially the same as those in FIG. 6 are given the same reference numerals, and descriptions thereof are omitted. In the circuit of this embodiment, the second transformer 8 and the diode 16 are omitted from the circuit of FIG. 2, and the auxiliary capacitor 41 and the auxiliary diode 42 are provided as in the case of FIG. The auxiliary capacitor 41 and the auxiliary diode 42 are connected between the output end of the reactor 4 and arbitrary first and second positions of the primary winding 7.

Since the circuit of FIG. 9 is basically the same as that of FIG. 6, it has the same effects as those of FIG.

[0033]

[Eighth Embodiment] Next, a DC power supply device according to an eighth embodiment of FIG. 10 will be described. However, in FIG. 10, parts that are substantially the same as those in FIG. 2 are given the same reference numerals, and descriptions thereof will be omitted. The circuit of FIG. 10 has the same configuration as that of FIG. 2 except that first and second backflow prevention diodes Da and Db are provided instead of the second rectifier circuit 27 of FIG. The first backflow blocking diode D1 is connected between the output terminal of the bridge rectifying circuit 3 and the reactor 4, and the second backflow blocking diode Db is connected to the output terminal of the rectifying circuit 3 and the capacitor 12.
Is connected between and. As a result, the cathodes of the first and second backflow prevention diodes Da and Db function as the first and second rectification output terminals.

Since the circuit of FIG. 10 is the same as that of FIG. 2 except for the rectifier circuit, it has the same effect as that of FIG. In addition,
The rectifier circuits of the circuits of FIGS. 4, 5, 6, 7, 8, 9 and 11 can be configured in the same manner as in FIG.

[0035]

[Ninth Embodiment] Next, a DC power supply device according to a ninth embodiment will be described with reference to FIGS. However, in FIG. 11, parts that are substantially the same as those in FIG. 6 are given the same reference numerals, and descriptions thereof are omitted. The circuit of FIG. 11 is the same as that of FIG. 2 except that a resonance capacitor Cx and a resonance switch Qx composed of a field effect transistor are added to the circuit of FIG. A series circuit of the resonance capacitor Cx and the switch Qx is connected in parallel to the intermittent switch 10. Since the two switches 10 and Q are both insulated gate field effect transistors whose sources are connected to the substrate (bulk), diodes D10 and Dq are provided in antiparallel to the main switches S10 and Sq as shown in FIG. In addition, the stray capacitance C10, in parallel with the main switches S10, Sq,
Has Cq. However, it is also possible to connect the diodes D10, Dq and the capacitor C10 as separate components.

The control circuit 20a for controlling the resonance switch Qx is for turning on the switch Qx during the off period of the control signal Vg1 shown in FIG. 12B obtained from the control circuit 20 of the intermittent switch 10. The control signal Vg2 is shown in FIG.
It occurs as shown in (D). In addition, an idle period in which both are turned off is provided between the on periods of the first and second control signals Vg1 and Vg2.

FIG. 12 shows the state of each part of FIG. 11, and (A) and (C) show the voltage between the terminals (drain-source voltage) V10 and Vg of the switch 10 and Qx, respectively.
(B) and (D) show control signals Vg1 and Vg2 applied to the gates of the switches 10 and Qx, and (E) and (F) flow to the main switches S10 and Sq of the switch 10 and Qx shown in FIG. The currents I10 and Iq are shown, and (G) shows the voltage Vcx of the resonance capacitor Cx.

The circuit of FIG. 11 has the same effect as that of FIG. 2 and also has the effect of reducing switching loss due to partial resonance operation.

In the circuit of FIG. 11, t1 to t of FIG.
During the ON period of the switch 10 shown in 2, the capacitor 12
A current flows through the closed circuit of the primary windings 7 and 9 and the switch 10, and a current flows through the closed circuit of the rectifier circuit, the reactor 4, the primary winding 9 and the switch 10. When the on / off switch 10 is controlled to be turned off at time t2, a current flows through the stray capacitance C10 of the switch 10 shown in FIG. 13 and is gradually charged. Therefore, the voltage V10 of the intermittent switch 10
Is gradually increased in the period from t2 to t3 as shown in FIG. This achieves zero volt switching at turn-off and reduces switching loss. t
When the charging of the stray capacitance C10 is completed at time 3, the current flows through the closed circuit composed of the capacitor 12, the primary windings 7 and 9, the capacitor Cx and the main switch Sq of the resonance switch Qx or the diode Dq, and at the same time, the rectifier circuit. And reactor 4
Current flows in a closed circuit composed of the primary winding 9, the capacitor Cx, the main switch Sq and the diode Dq. next,
The capacitor Cx is in the discharge mode, the closed circuit composed of the capacitor Cx, the primary windings 9 and 7, the capacitor 12 and the main switch Sq flows a current in the opposite direction (upward), and the rectifier circuit and the reactor 4 are connected. A current also flows in a closed circuit composed of the primary winding 7 and the capacitor 12. Since the capacitor Cx has a relatively large capacity, the voltage Vcx is maintained at a substantially constant DC voltage as shown in FIG. 12 (G) after being initially charged so that the right side becomes positive. Be drunk When the switch Qx is turned off at time t4, the stray capacitance C10 of the disconnecting switch 10 is reversely charged, and this voltage, that is, the voltage V10 of the disconnecting switch 10 is changed to that shown in FIG.
It decreases as shown in (A). The reverse charging current of the capacitor C10 flows in the closed circuit of the capacitor 12, the capacitor C10 and the primary windings 9 and 7. As a result, the capacitor 12 having the capacitance C10
Alternatively, it is returned to the capacitor 17 on the secondary side. At time t5, the intermittent switch 10 is controlled to be turned on, and the current I passes through it.
When 10 flows, the voltage of the switch 10 is almost zero volt, and the switching loss becomes small.

The circuits of the capacitor Cx and the switch Qx are shown in FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG.
It can also be added to the circuit. As a result, FIG.
The same effect as is obtained.

[0041]

[Modifications] The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible. (1) The switch 10 can be a semiconductor switch such as a bipolar transistor. (2) The polarities of the first and second rectifying circuits 3 and 27 and the switch 10 can be reversed.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a conventional DC power supply device.

FIG. 2 is a circuit diagram showing a DC power supply device according to a first embodiment.

FIG. 3 is a waveform diagram showing a state of each part of FIG.

FIG. 4 is a circuit diagram showing a DC power supply device of a second embodiment.

FIG. 5 is a circuit diagram showing a DC power supply device of a third embodiment.

FIG. 6 is a circuit diagram showing a DC power supply device of a fourth embodiment.

FIG. 7 is a circuit diagram showing a DC power supply device of a fifth embodiment.

FIG. 8 is a circuit diagram showing a DC power supply device of a sixth embodiment.

FIG. 9 is a circuit diagram showing a DC power supply device of a seventh embodiment.

FIG. 10 is a circuit diagram showing a DC power supply device of an eighth embodiment.

FIG. 11 is a circuit diagram showing a DC power supply device of a ninth embodiment.

12 is a waveform diagram of each part of FIG.

13 is an equivalent circuit diagram of the two switches of FIG.

[Explanation of symbols]

 4 Reactor 6, 8 First and second transformer 10 Switch 12 Capacitor

Claims (7)

[Claims] 1. A rectifier circuit connected to an AC power supply terminal and having first and second rectified output terminals and a common terminal, and connected between the first rectified output terminal and the common terminal Capacitor, a series circuit of a primary winding of a first transformer, a primary winding of a second transformer, and a switch, which are connected in parallel to the capacitor, and an output of the second rectifying circuit. An inductance circuit element connected between the terminal and the primary windings of the first and second transformers or between arbitrary positions of the primary windings of the first and second transformers; First and second transformer secondary windings, a first output rectifying diode connected between the secondary winding of the first transformer and an output smoothing capacitor, and a second transformer 2 Is connected between the secondary winding and the output smoothing capacitor, and A second output rectifying diode which is turned on when the first rectifying diode is off and has a directivity for charging the output smoothing capacitor; and a frequency of an AC voltage applied to the AC power supply terminal. A DC power supply device comprising: a control circuit for ON / OFF controlling the switch at a high repetition frequency. 2. The interconnection point between the output terminal of the inductance circuit element and the primary windings of the first and second transformers or the first winding of the primary winding of the first or second transformer.
A first auxiliary diode connected between the first position and the second position different from the first position of the output terminal of the inductance circuit element and the primary winding of the first or second transformer. The DC power supply device according to claim 1, further comprising a second auxiliary diode connected between the DC power supply device and the second auxiliary diode. 3. The interconnection point between the output terminal of the inductance circuit element and the primary windings of the first and second transformers, or the first winding of the primary winding of the first or second transformer. A second position different from the first position of the output terminal of the inductance circuit element and the primary winding of the first or second transformer, or the first capacitor An auxiliary diode connected to the interconnection point of the primary winding of the second transformer and connected in parallel to the auxiliary capacitor through at least a portion of the primary winding. 1. The DC power supply device according to 1. 4. A rectifier circuit, which is connected to an AC power supply terminal and has first and second rectified output terminals and a common terminal, and is connected between the first rectified output terminal and the common terminal. And a transformer connected in parallel to the capacitor.
It was connected between a series circuit of a secondary winding and an intermittent switch, and between the second rectified output terminal and a terminal of the primary winding on the switch side or an arbitrary position of the primary winding. An inductance circuit element, a secondary winding of the transformer, an output rectifying / smoothing circuit connected to the secondary winding, and the switch turned on at a repetition frequency higher than the frequency of the AC voltage applied to the AC power supply terminal. A DC power supply device that includes a control circuit that performs off control. 5. A first auxiliary diode connected between the output end of the inductance circuit element and a terminal of the primary winding on the switch side or a first position of the primary winding. And a second auxiliary diode connected between an output end of the inductance circuit element and a second position of the primary winding different from the first position. Power supply. 6. An auxiliary capacitor connected between the output end of the inductance circuit element and a terminal of the primary winding on the switch side or a first position of the primary winding, It is connected between an output end of the inductance circuit element and a second position different from the first position of the primary winding or a terminal of the primary winding on the switch side, and at least the primary winding. The DC power supply device according to claim 4, further comprising an auxiliary diode connected in parallel to the auxiliary capacitor through a part thereof. 7. A stray capacitance equivalently connected in parallel to the interrupting switch or an individual capacitor connected in parallel to the interrupting switch, and a built-in or individual capacitor connected in anti-parallel to the interrupting switch. A first resonance diode, a resonance switch connected in parallel to the intermittent switch through a capacitor, and a first resonance diode having a direction opposite to that of the first resonance diode; A built-in or individual second resonance diode connected in parallel to the resonance switch, and from a point slightly delayed from the start of the off-period of the intermittent switch, rather than the end of the off-period of the intermittent switch. The DC power supply device according to any one of claims 1 to 6, further comprising: a control circuit for ON-controlling the resonance switch until a time point slightly before.