JP3341802B2 - Switching 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 switching power supply such as a step-up DC-DC converter and a DC-DC converter having a power factor improving function.

[0002]

2. Description of the Related Art Step-up DC-DC without using a transformer
The circuit shown in FIG. 1 is known as a converter. In this circuit, a switch Q is connected in parallel via a reactor or inductance L between a pair of DC power supply terminals, and an electrolytic capacitor C is connected in parallel to the switch Q via a diode D. The switch Q is turned on / off by a control circuit. Energy is accumulated in the inductance L during the ON period of the switch Q, and the capacitor C is charged with the sum of the power supply voltage and the voltage of the inductance L during the OFF period of the switch Q. The voltage of the capacitor C is higher than the power supply voltage. Become. On the other hand, a rectifier is connected to the input terminal of the circuit of FIG. 1 and a waveform (pulsation) as shown in FIG. As shown in FIG. 2, an on / off control signal having a frequency sufficiently higher than the AC voltage turns on / off and
It is known that a triangular wave current having a peak corresponding to the amplitude of an AC voltage is passed as shown in FIG.

[0003]

The circuit shown in FIG. 1 can be used not only as a boost converter but also as a power supply having a high power factor. However, in the case of connecting and using an AC power supply via a rectifier, when an output voltage that is not much different from the input voltage is obtained, the sine wave approximation of the waveform of the input current is deteriorated, and a current having a large harmonic component is obtained. Have a problem. That is, when the output voltage is close to the effective value or the average value of the input AC voltage, a triangular wave which is relatively close to ideal near the maximum amplitude as shown in FIG. Instead of a triangle wave, it becomes trapezoidal. Therefore, the waveform of the envelope of the triangular wave current is a waveform having many harmonic components, and is a waveform having poor approximation to a sine wave.

In order to solve the above-mentioned problem, the present applicant has connected a diode at the position of the reactor L1 in the circuit of FIG. 3 and connected a capacitor C2 to the interconnection point 3 via the reactor. A switching power supply device having a configuration is proposed in Japanese Patent Application No. 6-84105. However, in the switching power supply of the above-mentioned application, there is no problem when the load does not change significantly, but there is a problem that when the load is significantly reduced, the voltage of the smoothing capacitor C1 becomes relatively high.

Accordingly, a first object of the present invention is to provide a switching power supply device that can easily obtain a boosted voltage and can easily suppress an increase in a smoothing capacitor.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a power supply capacitor connected between a pair of DC power supply terminals via a boosting reactor, and a power supply capacitor connected in parallel to the power supply capacitor. A series circuit of a first and a second switch connected thereto, and a transformer having a resonance inductance connected in parallel to the second switch.
A series circuit of a secondary winding and a resonance capacitor or a series circuit of a resonance reactor and a primary winding of a transformer and a resonance capacitor; and a series circuit of a transformer electromagnetically coupled to the primary winding.
A secondary winding; an output rectifying / smoothing circuit connected to the secondary winding; a switch control circuit for alternately turning on / off the first and second switches; The present invention relates to a switching power supply device including a boosting capacitor connected between one of the terminals and the boosting reactor and the other end connected between the primary winding and the resonance capacitor. .

It is possible to connect a capacitor for resonance and / or a capacitor for voltage division as set forth in claims 2, 3, 4, and 5. In addition, a rectifier circuit may be provided to supply a direct current. Further, the first and second boosting capacitors are connected to the first and second boosting capacitors.
And a second boosting reactor. Further, in the device of the seventh aspect, a voltage dividing capacitor or a resonance capacitor can be connected as described in the eighth and ninth aspects. In addition, as described in claim 10, the first to the fourth
And a series circuit of the first and second smoothing capacitors can be provided. Claim 11
As shown in the above, the device of claim 10 can be a voltage doubler circuit. Further, as shown in claims 12 and 13, in the device according to claim 10 or 11, a voltage dividing capacitor or a resonance capacitor can be connected. Claim 1
As shown in FIG. 4, first to fourth resonance capacitors, first and second boosting reactors, and first and second boosting capacitors can be provided.

[0008]

Operation and effect of the present invention First and second switches Q1,
The relationship between the on / off frequency f of Q2 and the output power P0, that is, the output current I0, is as shown in FIG. 6, and the relationship between the output current I0 and the peak value of the voltage Vcr of the resonance capacitor Cr is shown in FIG. As shown in FIG. In the present invention, the voltage Vcr of the resonance capacitor Cr is related to the charging of the smoothing capacitor C1. When the load becomes light, the voltage of the resonance capacitor Cr decreases, and the voltage of the smoothing capacitor C1 is suppressed from rising more than necessary. In the invention of each claim, the voltage of the resonance capacitor is related to the boost charging of the power supply or the smoothing capacitor. The voltage of the resonance capacitor decreases as the load decreases. Therefore, it is possible to prevent the voltage of the power supply or the smoothing capacitor from becoming unnecessarily high at a light load. Claims 2 to 5, 8, 9, 1
According to 2, 13, the contribution of the resonance capacitor to the boosting charge can be adjusted. Further, according to the inventions of claims 6 to 13, the power factor can be easily improved by using a converter circuit together. Further, the main circuit portion of the switching power supply device according to the second aspect can be shared by the boosting charging circuit of the capacitor and the DC-DC converter circuit. Therefore, cost can be reduced.

[0009]

First Embodiment Next, referring to FIG. 3 to FIG. 9, a switching power supply device according to a first embodiment of the present invention,
The DC converter will be described. The DC-DC converter shown in FIG. 3 includes an AC power supply 1 composed of a commercial power supply, a well-known high-frequency component removing filter 1b, and four diodes D1a to D1d.
DC rectifier circuit 1c.
A first smoothing capacitor C1 composed of an electrolytic capacitor (polar capacitor) is provided between a pair of power terminals 2a and 2b connected to the power source 1 via a boosting reactor L1.
Is connected. This smoothing capacitor C1 functions as a DC power supply for the switching regulator circuit. Therefore, the first and second capacitors are connected in parallel with the smoothing capacitor C1.
Is connected to a series circuit of the switches Q1 and Q2. The first and second switches Q1 and Q2 are composed of insulated gate (MOS) field effect transistors (FETs) whose sources are connected to the substrate. , And diodes Da and Db connected in anti-parallel. Of course, the switches Q1 and Q2 can also be constituted by bipolar transistors and diodes connected in anti-parallel to the bipolar transistors. Also, individual diodes can be provided without incorporating the diodes Da and Db.

In order to form an output circuit of a resonance type DC-DC converter, the connection point 3 between the first and second switches Q1 and Q2 and the lower end of the power supply capacitor C1, that is, the source of the second switch Q2 is connected. Inductance L for resonance between
A series circuit (an output resonance circuit) of a primary winding N1 having r and a capacitor C3 for resonance is connected. The primary winding N1 of the transformer T has an exciting inductance equivalently connected in parallel to the primary winding N1 in addition to the inductance Lr composed of a leakage inductance. The secondary winding N2 of the transformer T is divided into a first winding N2a and a second winding N2b by a center tap.
And a fourth diode D3, D4 connected to one end of an output smoothing capacitor C0, and a center tap connected to the other end of the capacitor C0. Output terminals 4 and 5 for connecting a load (not shown) are output smoothing capacitors C.
Connected to 0. In addition, between the full-wave rectifier composed of the diodes D3 and D4 and the capacitor C0, Japanese Patent Application No.
A choke coil may be connected similarly to FIG. 11 of No. 4105.

In order to form a partial resonance circuit for reducing the switching loss at the time of turning off the first and second switches Q1 and Q2, the first and second switches Q1 and Q2,
Capacitors Ca and Cb are connected in parallel with Q2.
The capacitors Ca and Cb are connected to the stray capacitance (stray capacitance) of the first and second switches Q1 and Q2.
It can be.

One end of the boosting capacitor C2 provided according to the present invention is connected between the DC power supply terminal 2a and the reactor L1, and the other end is connected between the primary winding N1 and the resonance capacitor Cr. I have.

A control circuit 6 for turning on and off the first and second switches Q1 and Q2 alternately includes a first and second switch Q1 and Q2 in response to a change in output voltage or input voltage.
It is configured to control the output voltage constant by changing the on / off frequency of 2. Therefore, the control circuit 6 controls the voltage detecting voltage dividing resistors 7 and 8 connected between the output terminals 4 and 5.
, Reference voltage source 9, error amplifier (differential amplifier) 10
, A light emitting diode 11, a phototransistor 12,
It comprises a resistor 13, a VCO (voltage controlled oscillator) 14, and a control signal forming circuit 15.

One input terminal of the error amplifier 10 is connected to a voltage dividing point of the voltage dividing resistors 7 and 8, and the other input terminal is connected to the reference voltage source 9. Therefore, an output voltage corresponding to the difference between the detection voltage and the reference voltage is obtained from the error amplifier 10. Since the light emitting diode 11 is connected between the output terminal of the error amplifier 10 and the ground, it emits light corresponding to the error output. The phototransistor 12 optically coupled to the light emitting diode 11 is connected via a resistor 13 between a power supply terminal indicated by + V and ground. Therefore, when the output voltage increases and the output of the light emitting diode 11 increases, the voltage of the resistor 13 decreases. Phototransistor 12
The VCO 14 connected to the voltage dividing point of the resistor 13 and the resistor 13
3 outputs a frequency signal proportional to the voltage. VCO14
The control signal forming circuit 15 which is connected to the VCO 14 shapes the output of the VCO 14 into a square wave, and sends the square wave control signal Vg1 shown in FIG. 7A to the control terminal (gate) of the first switch Q1 via the line 16a. 7B, and the phase of the waveform of the line 16a is inverted, and a dead time Td having a slight constant width is provided between the control signals V as shown in FIG. 7B.
g2 is supplied to the control terminal (gate) of the second switch Q2 via line 16b.

[0015]

[Outline of operation] A first capacitor C1 functioning as a DC power supply of a DC-DC converter is a bridge rectifier circuit 1c.
It is charged by the output of. This charging is performed with a boosting action with the reactor L1 and the capacitor C2. This boost charging is performed by the first and second switches Q of the DC-DC converter.
1 and Q2 are also used. First and second switches Q1, Q2 as shown in FIGS. 4A, 4B and 5B.
2 drives the series resonance circuit of the leakage inductance Lr of the primary winding N1 and the capacitor Cr, and outputs an output corresponding to the current, that is, the power based on the series resonance to the secondary winding N2 side of the transformer T. can get. The voltage at the output terminals 4, 5 is controlled by changing the on / off frequency of the first and second switches Q1, Q2.

[0016]

FIG. 8A shows the drain-source voltage Vq2 of the second switch Q2, and FIGS. 8B and 8C show the current Iq2 of the second and first switches Q2 and Q1. 8 (D) shows the current I2 flowing through the resonance capacitor Cr, FIG. 8 (E) shows the voltage Vcr of the resonance capacitor Cr, and FIG. 8 (F) shows the current flowing through the power supply terminal 2a. I
8 (G) shows the voltage Vc2 of the capacitor C2, and FIG. 8 (H) shows the current IL1 of the reactor L1.

[0017]

[Basic operation of DC-DC converter] When the smoothing capacitor C1 is already charged, t1 to t4 in FIG.
When the first switch Q1 is turned on at t4, a current I2 flows due to series resonance composed of a closed circuit of the smoothing capacitor C1, the first switch Q1, the primary winding N1, and the resonance capacitor Cr. Further, the second switch Q between t5 and t8
2 during the ON period, the resonance capacitor Cr and the primary winding N
A current I2 flows through a series resonant circuit comprising a closed circuit of the first and second switches Q2. First and second switches Q
1 and Q2 show the relationship between the on / off frequency f and the output current I0 due to series resonance, that is, the output voltage P, as shown in FIG. 6, and the maximum current when the on / off frequency f matches the resonance frequency f0 of LrCr. That is, it becomes the maximum power. In this embodiment, the output voltage V0 is controlled to be constant by changing the on / off frequency f in the range of f1 to f2. Since the magnitude (maximum amplitude) of the resonance current I2 of LrCr varies proportionally with the magnitude of the load, an effect of adjusting the output voltage occurs due to the change in the load, and it is not necessary to greatly change the on / off frequency. And the on / off frequency f changes in a narrow range. The on / off frequency f is lower than the time t1 in FIG. 4 showing the control signals Vg1 and Vg2, and the on / off frequency f is higher than the time t1.
Indicates a high state. As is clear from the above, the DC of FIG.
The basic operation of a DC converter is the same as that of the conventional resonance type D shown in FIGS. 11 and 19 of Japanese Patent Application No. 6-84105.
It is the same as a C-DC converter.

[0018]

[Charging Operation of Capacitor C1] The voltage Vcr of the resonance capacitor Cr becomes an AC voltage corresponding to the ON / OFF of the first and second switches Q1 and Q2 as shown in FIG.
When this voltage Vcr becomes lower than the voltage of the power supply terminal 2a,
Power supply terminal 2a, capacitor C2 and resonance capacitor Cr
A current Ic2 shown in FIG.
Thereafter, the boosting capacitor C2 and the boosting reactor L1
The circuit of switch Q1 and primary winding N1 makes reactor L1
When the switch Q1 is turned off, the smoothing capacitor C1 is boosted and charged by the circuit of the boosting capacitor C2, the reactor L1, the smoothing capacitor C1, and the resonance capacitor Cr. Thus, the smoothing capacitor C1 can be charged to a voltage higher than the voltage of the power supply terminal 2a. Voltage Vcr of capacitor Cr for resonance
Varies depending on the magnitude of the load, and decreases when the load is light or no load. For this reason, the sum of the voltage of the capacitor C2 and the voltage Vcr of the resonance capacitor Cr at the time of light load and no load is also reduced, and the rise of the smoothing capacitor C1 more than necessary can be suppressed. When the voltage of the smoothing capacitor C1 is limited, the capacitor C1 and the first and second switches Q1 and Q2 can have low withstand voltage and low cost.

Next, the operation in each section of FIG. 8 will be described in detail. In order to simplify the description, the current paths are indicated by the arrangement of only the reference numerals of each circuit element in FIG.

In the section from t1 to t2 in FIG. 8, 1-C2-C
with flowing a charging current Ic2 of the capacitor C2 in a closed circuit of r, 1 -C2 -N1 -Q1 -C1 charging current of closed circuit smoothing capacitor C1 flows.

In the section from t2 to t3, the resonance capacitor C
Since the voltage of r rises, the charging current I2 of the boosting capacitor C2 stops flowing. Conversely, the discharging current of the capacitor C2 flows in the circuit of C2-L1-Q1-N1, and energy is accumulated in the reactor L1. . In this section, due to the converter operation, the resonance current shown in FIG. 8D flows through the resonance circuit of C1-Q1-N1-Cr, and power is supplied to the load.

In the section between t3 and t4, a current flows through the same circuit as in the previous section between t2 and t3. The section from t3 to t4 is a section after the high-frequency resonance due to the leakage inductance Lr of the primary winding N1 is completed, and is a section through which a low-frequency resonance current flows due to the exciting inductance of the primary winding N1.

In the section from t4 to t5, C2-L1-Ca-
Energy is stored in the reactor L1 in the circuit of N1. In the converter circuit, since the dead time period is reached, the partial resonance capacitor Ca is charged by the circuit of C1-Ca-N1-Cr, and the voltage of the first switch Q1 gradually increases to achieve zero volt switching. Then, the capacitor Cb is discharged in the circuit of Cb-N1-Cr, and the second switch Q2 is ready for zero volt switching.

In the section from t5 to t6, the second switch Q2
Is on and the first switch Q1 is off. As a result, a circuit of C2-L1-C1-Cr is formed, and the smoothing capacitor C1 is boosted and charged by discharging the energy of the reactor L1. Also, the converter circuit Cr-N1-Q2
The resonance current I2 flows through the circuit. When the voltage Vcr of the resonance capacitor Cr is low with a light load or no load, the charging voltage of the smoothing capacitor C1 also becomes low, and this charging is suppressed or not performed. As a result, an unnecessary rise of the voltage of the smoothing capacitor C1 is limited.

In the interval from t6 to t7, the resonance capacitor C
Since the voltage Vcr of r is low, 1-C2 -N1 -Q2
The circuit for charging the boosting capacitor C2. Note that, in the converter circuit, as in the previous section, Cr-N1
Resonant current flows at -Q2.

In the section between t7 and t8, a current flows on the same path as the previous section. However, the high frequency resonance current of Cr Lr does not flow in the interval t7 to t8 as in the interval t3 to t4, and the low frequency resonance current due to the exciting inductance flows.

In the section from t8 to t9, that is, in the section from t8 to t1 corresponding to t1, the charging of the capacitor C2 is performed by 1-C2-
It is continued in the circuit of N1 -Cb. Since the dead time period is reached, the capacitor Cb for partial resonance is charged by Cr-N1-Cb to achieve zero volt switching of the second switch Q2, and the capacitor for partial resonance in the circuit Ca-C1-Cr-N1 is used. Capacitor Ca discharges and zero volt switching of first switch Q1 is achieved. Thus, one cycle of operation is completed.

This embodiment has the following effects. (1) The capacitor C1 can be charged higher than the voltage of the power supply 1 by using the ON / OFF of the switches Q1 and Q2 of the DC-DC converter. (2) As shown in FIG. 5C, the power supply I1 has a waveform in which the peak value changes according to the amplitude of the voltage, and the power factor is improved. (3) The contribution of the capacitor Cr of the resonance circuit to the boost charging of the capacitor C1 is caused by the first and second switches Q1,
As the on / off frequency f of Q2 becomes higher, that is, becomes lower as the load becomes lighter, the voltage of the capacitor C1 can be prevented from rising more than necessary.

[0029]

Second Embodiment Next, a switching power supply according to a second embodiment will be described with reference to FIG. However, in the drawings showing the second embodiment and another embodiment described later, FIGS.
The same reference numerals are given to substantially the same portions as those described above, or portions common to each embodiment, and the description thereof is omitted.

The circuit shown in FIG. 9 is different from the circuit shown in FIG. 3 in that a capacitor Cn, a diode Dn and a capacitor C
The configuration is the same as that of FIG. 3 except that f is added. The capacitor Cn is connected in parallel with the series circuit of the diode Dn and the reactor L1. The diode Dn is connected between the power supply terminal 2a and the capacitor C2. The capacitor Cf is connected between the cathode of the diode Dn and the other power supply terminal 2b. Since the capacitors Cn and Cf are for noise removal,
This is a small-capacity high-frequency capacitor.

[0031]

Third Embodiment The circuit of the third embodiment shown in FIG.
This circuit has the same configuration as that of FIG. 3 except that first and second voltage dividing capacitors C3 and C4 are added to the circuit of FIG. That is,
A series circuit of first and second voltage dividing capacitors C3 and C4 is connected in parallel with the resonance capacitor Cr.
A boosting capacitor C2 is connected to a connection point of the second voltage dividing capacitors C3 and C4. Therefore, all of the voltage Vcr of the resonance capacitor Cr becomes equal to the smoothing capacitor C1.
It does not participate in charging, but only part of it. That is, the sum of the voltage of C4 and the voltage of C2 is the charging voltage of the capacitor C1. Thus, a desired voltage of the smoothing capacitor C1 can be accurately and easily obtained. The third
This embodiment also has the same functions and effects as the first embodiment.

[0032]

Fourth Embodiment A circuit shown in FIG. 11 according to a fourth embodiment has a configuration in which a series circuit of first and second resonance capacitors Cr1 and Cr2 is connected in place of one resonance capacitor Cr in FIG. The configuration is the same as that of FIG. 3 except that a capacitor C2 is connected to the interconnection point between the first and second resonance capacitors Cr1 and Cr2. The capacitor C of the circuit of FIG.
r1 and Cr2 are the first and second voltage dividing capacitors C of FIG.
3, has substantially the same effect as C4.

[0033]

Fifth Embodiment The circuit of FIG. 12 showing the fifth embodiment is as follows.
A parallel circuit of first and second resonance capacitors Cr1 and Cr2 is connected instead of one resonance capacitor Cr in FIG. Even with such a configuration, the same operation and effect as the circuit of FIG. 3 can be obtained.

[0034]

Sixth Embodiment A circuit according to a sixth embodiment shown in FIG.
First and second reactors L1, L2 are connected between the pair of power terminals 2a, 2b and the smoothing capacitor C1, respectively. First and second reactors L1 for boosting
, L2 are connected to the terminals 2a and 2b of the first and second boosting capacitors C2 and C5, respectively, and the other ends thereof are mutually connected in order to relate the boosting charging of the smoothing capacitor C1. Connected to the interconnection point of the first and second voltage dividing capacitors C3 and C4. A series circuit of the first and second voltage dividing capacitors C3 and C4 is connected in parallel with the resonance capacitor Cr. Also,
First and second auxiliary capacitors C6 and C7 are connected between one and other terminals of the AC power supply 1a and the lower terminal of the smoothing capacitor C1. 13 except for the above in FIG.
It is configured identically.

The basic operation of the circuit of FIG. 13 is the same as the operation of the circuit of FIG. Therefore, the operation of the circuit of FIG. 13 will be described for each section of FIG. Since the converter operation is the same as that of the circuit of FIG. 3, its detailed description is omitted, and mainly the charging operation of the smoothing capacitor C1 will be described. The case where the AC power supply 1a generates a positive half wave will be described. In the period corresponding to the section between t1 and t2 in FIG.
The first boosting capacitor C2 is charged in a closed circuit of 2-C3-Cr-C7. At the same time, t5 of the circuit of FIG.
The operation corresponding to the section from time t6 to time t6 occurs on the side of the second reactor L2, and the second boosting capacitor C5 discharges and charges the smoothing capacitor C1 in the circuit of C5-C3-N1-Q1-C1-L2. Since energy is stored in the second reactor L2 in the previous period, the smoothing capacitor C1 is boosted and charged with the release of this energy.

During the period corresponding to t2 to t3 in FIG. 8 for the first boosting capacitor C2, the first boosting capacitor C1 is connected to the circuit of C3-C2-L1-Q1-N1 in addition to the converter operation. Discharge occurs and energy is stored in the first reactor L1. At the same time, an operation corresponding to the section from t6 to t7 in FIG. 8 occurs in relation to the second reactor L2 on the lower side, and the second operation is performed in the circuit of C6 -Cr -C3 -C5-1.
Is charged.

In the period corresponding to t3 to t4 in FIG. 8 for the first boosting capacitor C2, the same operation as in the previous period occurs. The second boosting capacitor C5 is the same as the previous section, and the charging current flows through the second boosting capacitor C5 by the operation corresponding to the section from t7 to t8 in FIG.

In the period corresponding to t4 to t5 in FIG. 8 for the first boosting capacitor C2, C3 -C2 -L1
The discharge of the first boosting capacitor C2 occurs in the circuit of -Ca-N1, and energy is accumulated in the first reactor L1. The operation of the second boosting capacitor C5 is the same as that in the previous section, and a charging current corresponding to t8 to t9 in FIG. 8 flows through the second boosting capacitor C5.

In the section corresponding to t5 to t6 in FIG. 8 for the first boosting capacitor C2, the first switch Q
1 is off, the discharging of the first boosting capacitor C2 and the discharging of the energy of the first reactor L1 are performed along the path of C3-C2-L1-C1-Cr, and the smoothing capacitor C1 is boosted and charged. You. In the second boosting capacitor C5, the charging current flows on the same path as the previous section according to the same operation as the section from t1 to t2 in FIG.

In the section corresponding to t6 to t7 in FIG. 8 for the first boosting capacitor C2, 1a-1c-C2
The charging current of the first boosting capacitor C2 flows at -C3 -Cr -C7. As for the second boosting capacitor C5, similarly to the section between t2 and t3 in FIG. 8, C5 -C3 -N
In the 1-Q2-L2 circuit, the second boosting capacitor C5 is discharged, and this energy is stored in the second reactor L2.

In the section corresponding to t7 to t8 in FIG. 8 for the first boosting capacitor C2, the charging current of the first boosting capacitor C2 flows in the same circuit as the previous section. As for the second boosting capacitor C5, FIG.
Corresponding to the interval t3 to t4 of the second step-up capacitor C.
The discharge of 5 and the accumulation of energy in the second reactor L2 occur on the same path as in the previous section.

In the section corresponding to t8 to t9 in FIG. 8 for the first boosting capacitor C2, 1a-1c-C2
The charging of the first boosting capacitor C2 is performed along the path of -C3 -N1 -Cb -C7, and the second boosting capacitor C5 is operated in the same manner as in the section from t4 to t5 in FIG. In the circuit of -N1 -Cb -L2, discharge of the second boosting capacitor C5 and accumulation of energy in the second reactor L2 occur. Note that the same operation as described above occurs even during the period when the AC power supply 1a generates a negative half-wave.
However, in this case, the first and second boosting capacitors C
2. The charge / discharge of C5 is opposite to the case of positive half-wave.

Since the basic principle of the circuit of FIG. 13 is the same as that of the circuit of FIG. 3, it has the same function and effect as the circuit of FIG.

[0044]

Seventh Embodiment The circuit of the seventh embodiment shown in FIG.
The resonance capacitor Cr and the voltage dividing capacitor C of the circuit 3
3 and C4 instead of the first and second resonance capacitors Cr.
1, except that a series circuit of Cr2 is provided. First and second boosting capacitors C2,
The other end of C5 is connected to first and second resonance capacitors Cr1, C2.
It is connected to the interconnection point of r2, ie the voltage division point. Therefore,
This is a voltage division method similar to the circuit of FIG. According to this embodiment, the same operation and effect as those of the circuit of FIG. 13 can be obtained.

[0045]

Eighth Embodiment The circuit of the eighth embodiment shown in FIG. 15 is obtained by removing the voltage dividing capacitors C3 and C4 from the circuit of FIG. 13 and resonating the other ends of the first and second boosting capacitors C2 and C5. The configuration is the same as that of FIG. 13 except that it is connected to the upper end of the capacitor Cr for use. The circuit shown in FIG.
The same operation and effect as those of the third circuit can be obtained.

[0046]

Ninth Embodiment A circuit according to a ninth embodiment shown in FIG. 16 is capable of obtaining a doubled voltage. For this,
The first, between one terminal and the other terminal of the AC power supply 1a,
Second, third and fourth diodes D1a, D1b, D1c, D
A bridge circuit 1d is connected, a series circuit of first and second smoothing capacitors C1a and C1b is connected between a pair of DC output lines, and the other terminal of the AC power supply 1a is connected to the first and second smoothing capacitors C1a and C1b. A switch SW as a selective connection means is connected between an interconnection point of the capacitors C1a and C1b.
Is connected between the cathode of the first diode D1a and the cathode of the second diode D1b, and the second reactor L2 is connected between the anodes of the third and fourth diodes D1c and D1d. , A first boosting capacitor C2 is connected between the cathode of the first diode D1a and the first voltage dividing capacitor C3, and a second boosting capacitor C5 is connected between the anode of the third diode D1c and the first The series circuit of the first and second switches Q1 and Q2 is connected in parallel with the series circuit of the first and second smoothing capacitors (doubler capacitors) C1a and C1b. It is connected to the. 16 is the same as FIG. 13 except for the above.

The smoothing capacitors C1a and C1 in the circuit of FIG.
Since the basic principle of the step-up charging of 1b is the same as that of the circuit of FIG. 3, it corresponds to each section of FIG. 8 showing the operation of FIG.
The operation of the circuit of FIG. The state where the switch SW is off will be described. Also, since the converter operation of the circuit of FIG. 16 is the same as that of the circuit of FIG. 3, this description will be omitted, and the charging operation of the capacitors C1a and C1b will be described. Further, a period during which the AC power supply 1a generates an upward voltage (positive half wave) will be described.

First boosting capacitor C in the circuit of FIG.
In the section corresponding to t1 to t2 in FIG.
The first boosting capacitor C2 is charged by the circuit of -D1a-C2 -C3 -Cr -D1d. Further, in the second boosting capacitor C5, L2-C5-C3-N1-Q1
In the circuit of -C1a-C1b, the energy of the second reactor L2 is discharged and the second boosting capacitor C5 is discharged, and the first and second smoothing capacitors C1a and C1b are boosted and charged.

T for the first boosting capacitor C2
In the section corresponding to 2 to t3, C2-L1-Q1-N1
In the circuit of -C3, the first boosting capacitor C2 is discharged, and the energy of the first reactor L1 is accumulated. The discharging mode of L2 C5 is maintained for the second boosting capacitor C5 during the entire positive half-wave period.

T for the first boosting capacitor C2
In the section corresponding to 3 to t4, C2-L1-Q1-N1
In the circuit of -C3, the first boosting capacitor C5 is discharged, and energy is accumulated in the first reactor L1.

T for the first boosting capacitor C2
In the section corresponding to 4 to t5, C2-L1-Ca-N1
The circuit of -C3 discharges the first boosting capacitor C2 and stores the energy of the first reactor L1.

T for the first boosting capacitor C2
In the section corresponding to 5 to t6, C2-L1-C1a-C1b
In the circuit of -Cr-C3, the first and second smoothing capacitors C1a and C1b are boosted and charged by discharging the first boosting capacitor C2 and discharging the energy of the first reactor L1.

T for the first boosting capacitor C2
In the section corresponding to 6 to t7, 1a-D1a-C2-C3
The first boosting capacitor C2 is charged by the circuit of -Cr -D1d.

T for the first boosting capacitor C2
In the section corresponding to 7 to t8, the first boosting capacitor C2 is charged by the same circuit as in the previous section.

T for the first boosting capacitor C2
In the section corresponding to 8 to t9, 1a-D1a-C2-C3
-N1 -Cb -L2 circuit and the second boost capacitor C
5 is discharged, and energy is stored in the second reactor L2.

The operation of the AC power supply 1a during the negative half-wave period is opposite to the operation during the positive half-wave period, and a discharge circuit of the first boosting capacitor C2 and the first reactor L1 is formed.
On the other hand, the second boosting capacitor C5 and the second reactor L2 repeat charging and discharging similarly to C2 and L1 in the positive half-wave period. When the switch SW is turned on, the first and second smoothing capacitors C1a and C1b are each charged higher than the power supply voltage, and a doubled voltage can be obtained. For example, in a section corresponding to t5 to t6 of the positive half-wave period of the AC power supply, the first smoothing capacitor C1a is boosted and charged by the circuit of 1a-D1a-L1-C1a-SW. Further, during the negative half-wave period of the AC power supply, the first smoothing capacitor C1b is boosted and charged by 1a-SW-C1b-L2-D1c. Energy is stored in the first and second reactors L1 and L2 as in the case of full-wave rectification.

Since the principle of the boosting charge of the circuit of FIG. 16 is substantially the same as that of FIGS. 3, 13 and the like, the same operation and effect can be obtained.

[0058]

Tenth Embodiment A switching power supply according to a tenth embodiment shown in FIG. 17 includes third and fourth resonance capacitors Cr3 and Cr4 and a second boosting reactor L2 in the circuit shown in FIG.
And a second boosting capacitor C2b, and the others correspond to those formed substantially the same as in FIG. First, second, third, and fourth resonance capacitors Cr1, Cr
2, Cr3 and Cr4 are connected in series with each other, and this series circuit is connected in parallel with the smoothing capacitor C1. Primary winding N
The upper end of 1 is connected to the interconnection point of the second and third resonance capacitors Cr2 and Cr3, and the lower end is connected to the interconnection point 3 of the first and second switches Q1 and Q2. One end of the first boosting capacitor C2a is connected to a power supply side terminal of the first boosting reactor L1, and the other end is connected to an interconnection point of the first and second resonance capacitors Cr1 and Cr2. . One end of the second boost capacitor C2b is connected to the second
Is connected to the power supply side terminal of the step-up reactor L2, and the other end thereof is connected to the interconnection point of the third and fourth resonance capacitors C3 and C4.

In the circuit of FIG. 17, the switches Q1 and Q
2 causes charging and discharging of the boosting capacitors C2a and C2b, and the first and second boosting reactors L1,
The accumulation and release of the energy of L2 also occurs, and the smoothing capacitor C1 is boosted and charged. Since the basic operation of the circuit of FIG. 17 is the same as that of the first to ninth embodiments, the circuit of FIG. 17 has the same operation and effect.

[0060]

[Modifications] The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible. (1) In FIG. 16, the voltage dividing capacitors C3 and C4
And the resonance capacitor Cr as a series circuit of two resonance capacitors Cr1 and Cr2 as shown in FIG.
Alternatively, as shown in FIG. 15, C3 and C4 can be omitted and only Cr can be used. (2) A third resonance capacitor may be connected in parallel with the series circuit of the first and second resonance capacitors Cr1 and Cr2 in FIGS. FIG.
1 and the first and second resonance capacitors Cr1,
A series circuit of the third and fourth capacitors may be connected in parallel to the series circuit of Cr2. Also, the same modification as described above is possible in FIG. (3) In addition to the inductance of the primary winding N1 of the transformer T, a resonance reactor can be connected in series to the primary winding N1. Also, an inductance can be connected in parallel with the primary winding N1. (4) The first and second switches Q1, Q2 can be controlled to turn off the first and second switches Q1, Q2 before t3 and t7 in FIG. (5) In FIGS. 3 and 9 to 15, a small-capacity high-frequency capacitor can be connected between the terminals 2a and 2b for noise removal or the like. (6) A backflow prevention diode can be connected in series with the bridge circuit 1c. (7) The power supply 1 can be a DC power supply such as a battery. In this case, a backflow prevention diode is connected in series with the power supply. (8) Noise removing capacitors Cn and Cf shown in FIG.
, Diode Dn can be provided in the circuit of another embodiment. (9) The switch SW in FIG. 16 can be omitted, or a fixed connection can be used instead of the switch SW. (10)
3, 9, 10, 11 and 12, the reactor L1 is connected to the line between the power supply terminal 2b and the second switch Q2, and the primary winding N1 and the resonance capacitor Cr or Cr1 to.
A series circuit with a plurality of circuits selected from Cr4 is connected to a first switch Q
1 can be connected in parallel. The terminals 2a, 2
b, the polarities of the switches Q1, Q2, etc. can all be reversed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a conventional step-up DC-DC converter.

FIG. 2 is a waveform diagram of each part when the circuit of FIG. 1 is used for power factor improvement.

FIG. 3 is a circuit diagram illustrating a switching power supply device according to a first embodiment.

FIG. 4 is a waveform diagram illustrating a switch control signal of FIG. 3;

FIG. 5 shows the output voltage of the rectifier circuit of the circuit of FIG.
FIG. 3 is a waveform chart showing a relationship between ON / OFF of No. 1 and a current of a rectifier circuit.

6 is a diagram showing a relationship between output power and on / off frequency of a switch in a resonance circuit of a transformer primary winding of FIG. 3;

7 is a diagram showing the relationship between the load current I0 of FIG. 3 and the peak value of the voltage Vcr of the resonance capacitor Cr.

8 is a waveform chart showing the state of each part of the circuit of FIG.

FIG. 9 is a circuit diagram illustrating a switching power supply device according to a second embodiment.

FIG. 10 is a waveform diagram illustrating a switching power supply device according to a third embodiment.

FIG. 11 is a circuit diagram showing a switching power supply device according to a fourth embodiment.

FIG. 12 is a circuit diagram showing a switching power supply device according to a fifth embodiment.

FIG. 13 is a circuit diagram showing a switching power supply device according to a sixth embodiment.

FIG. 14 is a circuit diagram showing a switching power supply device according to a seventh embodiment.

FIG. 15 is a circuit diagram illustrating a switching power supply device according to an eighth embodiment.

FIG. 16 is a circuit diagram showing a switching power supply according to a ninth embodiment.

FIG. 17 is a circuit diagram showing a switching power supply device according to a tenth embodiment.

[Explanation of symbols]

 Q1, Q2 First and second switches C1 Smoothing capacitor C2 Boost capacitor L1 Boost reactor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02M 3/28 H02M 3/337

Claims (14)

(57) [Claims] A power supply capacitor connected between a pair of DC power supply terminals via a step-up reactor; a series circuit of first and second switches connected in parallel to the power supply capacitor; A series circuit of a primary winding of a transformer having a resonance inductance and a resonance capacitor connected in parallel to the second switch, or a series connection of a resonance reactor, a primary winding of a transformer, and a resonance capacitor; A circuit; a secondary winding of a transformer electromagnetically coupled to the primary winding; an output rectifying / smoothing circuit connected to the secondary winding; and turning on / off the first and second switches alternately. One end is connected between one of the pair of DC power terminals and the step-up reactor, and the other end is connected between the primary winding and the resonance capacitor. Switching power supply device comprising: a boost capacitor; 2. The resonance capacitor according to claim 1, wherein a plurality of resonance capacitors are connected in series, and the other end of the boosting capacitor is connected between the plurality of resonance capacitors. The switching power supply device according to claim 1. 3. A booster circuit comprising a series circuit of first and second voltage dividing capacitors connected in parallel to the resonance capacitor, wherein the other end of the boosting capacitor is connected to the first and second voltage dividing capacitors. 2. The switching power supply according to claim 1, wherein the switching power supply is connected to an interconnection point of a voltage dividing capacitor. 4. The switching power supply device according to claim 3, wherein a third voltage dividing capacitor is connected in parallel with said second voltage dividing capacitor. 5. The switching power supply device according to claim 1, wherein the resonance capacitor includes a plurality of capacitors connected in parallel to each other. 6. The rectifier circuit according to claim 1, further comprising a rectifier circuit connected to said pair of DC power supply terminals.
Or the switching power supply device according to 3 or 4 or 5. 7. A rectifier circuit connected to a pair of AC power supply terminals, one end of which is connected to one output terminal of the rectifier circuit via a first boosting reactor, and the other end of which is connected to a second booster terminal. A smoothing capacitor connected to the other output terminal of the rectifier circuit via a reactor, a series circuit of first and second switches connected in parallel to the smoothing capacitor, and the second switch A series circuit of a primary winding of a transformer having a resonance inductance and a resonance capacitor or a series circuit of a resonance reactor and a primary winding of a transformer and a resonance capacitor, which are connected in parallel with each other; A secondary winding of a transformer electromagnetically coupled to the secondary winding; an output rectifying / smoothing circuit connected to the secondary winding; and a switch for turning on and off the first and second switches alternately. A control circuit, one end of which is connected between one output terminal of the rectifier circuit and the first boosting reactor;
A first winding connected between the next winding and the resonance capacitor;
A boosting capacitor having one end connected between the other output terminal of the rectifier circuit and the second boosting reactor, and the other end connected to the first boosting capacitor.
A second winding connected between the next winding and the resonance capacitor;
And a first and a second auxiliary capacitor respectively connected between the pair of AC power supply terminals and the other end of the smoothing capacitor. And a series circuit of first and second voltage dividing capacitors connected in parallel to the resonance capacitor, wherein the other ends of the first and second voltage boosting capacitors are connected to each other. 8. The switching power supply according to claim 7, wherein the switching power supply is connected to an interconnection point of the first and second voltage dividing capacitors. 9. The resonance capacitor in which a plurality of resonance capacitors are connected in series, and the other ends of the first and second boosting capacitors are respectively connected between the plurality of resonance capacitors. The switching power supply device according to claim 7, wherein 10. A pair of AC power terminals, a first diode having an anode connected to one of the pair of AC power terminals, and a second diode having an anode connected to the other of the pair of AC power terminals. A third diode having a cathode connected to the one AC power supply terminal, a fourth diode having a cathode connected to the other AC power supply terminal, a cathode of the first diode and a third diode. A first boost reactor connected between the cathode of the diode, a second boost reactor connected between the anode of the third diode and the anode of the fourth diode, And a series circuit of a second smoothing capacitor,
A smoothing capacitor series circuit having one end connected to the cathode of the second diode and the other end connected to the anode of the fourth diode; and a first connected in parallel to the smoothing capacitor series circuit. A series circuit of a primary coil of a transformer having a resonance inductance and a resonance capacitor connected in parallel with the second switch, or a series circuit of a resonance switch and one of a resonance reactor and a transformer. A series circuit of a secondary winding and a resonance capacitor; a secondary winding of a transformer electromagnetically coupled to the primary winding; an output rectifying and smoothing circuit connected to the secondary winding; A switch control circuit for alternately turning on and off a second switch, one end of which is connected between the first diode and the first boosting reactor, and the other end of which is connected to A first boosting capacitor connected between the primary winding and the resonance capacitor; one end connected between the third diode and the second boosting reactor; And a second boosting capacitor connected between the primary winding and the resonance capacitor. 11. The apparatus according to claim 11, further comprising means for selectively or fixedly connecting the other AC power supply terminal and an interconnection point of the first and second smoothing capacitors. The switching power supply device according to claim 10. And a series circuit of first and second voltage dividing capacitors connected in parallel to the resonance capacitor, wherein the other ends of the first and second voltage boosting capacitors are connected to each other. 2. The capacitor according to claim 1, wherein the capacitor is connected to an interconnection point of the first and second voltage dividing capacitors.
12. The switching power supply according to 0 or 11. 13. The resonance capacitor includes a plurality of resonance capacitors connected in series, and the other ends of the first and second boosting capacitors are respectively connected between the plurality of resonance capacitors. The switching power supply device according to claim 10 or 11, wherein 14. A pair of DC power terminals, one end of which is connected to one of the pair of DC power terminals via a first boosting reactor, and the other end of which is connected via a second boosting reactor. A smoothing capacitor connected to the other of the DC power supply terminals, a series circuit of first and second switches connected in parallel to the smoothing capacitor, and a parallel circuit connected to the smoothing capacitor. First,
A series circuit of second, third and fourth resonance capacitors;
A primary winding of a transformer having a resonance inductance whose one end is connected to an interconnection point of the first and second switches and the other end is connected to an interconnection point of the second and third resonance capacitors. A wire or resonance reactor, a primary winding and a series circuit of a transformer, a secondary winding of a transformer electromagnetically coupled to the primary winding, an output rectifying and smoothing circuit connected to the secondary winding, A switch control circuit for alternately turning on and off the first and second switches, one end of which is connected between the one DC power supply terminal and the first boosting reactor, and the other end of which is connected to the first boosting reactor. A first capacitor connected to the interconnection point of the first and second resonance capacitors.
A boosting capacitor, one end of which is connected between the other DC power supply terminal and the second boosting reactor, and the other end of which is connected to an interconnection point of the third and fourth resonance capacitors. The second
A switching power supply comprising: