JPH10146048A - Chopper type dc-dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce switching loss and surge voltage by turning off a switching element thereby discharging a first capacitor for resonance and charging a second capacitor for resonance in sine wave, and turning on it thereby discharging the second capacitor for resonance thereby letting a resonance current flow to the switching element. SOLUTION: While a transistor (switching element) 2 is on, a current 1 flows to load 6 through a transistor 2, a reactor 10 for resonance, and a reactor 4 so as to charge a first capacitor 8 for resonance to the voltage E of DC power source 1. When the transistor 2 turns from ON condition to OFF condition, electricity is discharged to the side of load 6 through the reactor 4 from the first capacitor 8 for resonance, and the second capacitor 14 for resonance is charged from 0V to sine waveform. Hereby, zero voltage and zero current switching is achieved at OFF and ON of the transistor 2, so surge voltage, surge currents, and noise can be reduced, reducing the switching loss of the transistor 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a chopper type DC-D.
The present invention relates to a C converter, particularly to a chopper type DC-DC converter having a small number of components and a small switching loss.

[0002]

2. Description of the Related Art DC power from a DC power supply is intermittently converted by direct on / off operation of a switching element into high-frequency power, and this high-frequency power is smoothed by a reactor and an output capacitor and converted into DC power again. 2. Description of the Related Art A chopper type DC-DC converter that supplies a DC output of a voltage different from the voltage of a DC power supply to a load has been widely used in power supply circuits of electronic devices and the like. For example,
The conventional step-down chopper type DC-DC converter shown in FIG. 6 includes a DC power supply 1, a transistor 2 as a switching element having a collector terminal (one main terminal) connected to a positive terminal (one end) of the DC power supply 1, An output diode 3 as a feedback output rectifier connected between the emitter terminal (the other main terminal) of the transistor 2 and the negative terminal (the other end) of the DC power supply 1, and one end of the transistor 2 and the output diode 3 , An output capacitor 5 connected between the other end of the reactor 4 and the negative terminal of the DC power supply 1, a load 6 connected in parallel with the output capacitor 5, and a transistor 2 And a control circuit 7 for applying a control pulse signal to the base terminal of the transistor 2 to control on / off of the transistor 2. This step-down chopper type D
In the C-DC converter, a DC output of a voltage lower than the voltage of the DC power supply 1 is supplied to the load 6 by controlling on / off of the transistor 2.

Further, a conventional boost chopper type D shown in FIG.
The C-DC converter includes a DC power source 1 and a switching device in which a collector terminal is connected to a positive line (one line) of the DC power source 1 and an emitter terminal is connected to a negative line (the other line) of the DC power source 1. A transistor 2 as an element, a reactor 4 connected to a positive line between the DC power supply 1 and the transistor 2, and an anode terminal (one end)
An output diode 3 as an output rectifier connected to the collector terminal of the transistor 2, an output capacitor 5 connected between the cathode terminal (the other end) of the output diode 3 and the negative line of the DC power supply 1, A transistor 6 is turned on by applying a control pulse signal to the load 6 connected in parallel with the output capacitor 5 and the base terminal of the transistor 2.
And a control circuit 7 for performing off control. In this step-up chopper type DC-DC converter, a DC output of a voltage higher than the voltage of the DC power supply 1 is supplied to the load 6 by controlling the on / off of the transistor 2.

[0006] A control circuit 7 shown in FIGS.
The on-period of the transistor 2 is controlled by changing the time width of the control pulse signal applied to the base terminal of the transistor 2 in proportion to the fluctuation of the terminal voltage of the transistor 2, thereby stabilizing the DC power supplied to the load 6. I'm trying.

[0005] Step-down and step-up chopper type D shown in FIGS.
In the C-DC converter, when the transistor 2 is turned on or turned off, as shown in FIG. 8, large switching based on the overlapping portion W of the collector-emitter voltage waveform V _CE of the transistor 2 and the collector current waveform I _C of the transistor 2 is performed. There is a disadvantage that loss occurs. The voltage waveform V between the collector and the emitter of the transistor 2
_Since the rising of the _CE and the collector current waveform I _C is steep, spike-shaped surge voltage V _sr , surge current I _sr and noise are generated.

In order to solve the above problems, the inventor of the present application has previously proposed a chopper type DC-DC converter shown in FIGS. 9 to 12 and disclosed in Japanese Patent Application No. 7-283959 on Oct. 31, 1995. A patent application has been filed. The chopper type DC-DC converters shown in FIGS. 9 and 10 correspond to the step-down and step-up chopper type DC-Ds shown in FIGS. 6 and 7, respectively.
In the C converter, one end of the first resonance capacitor 8 and one end of the first diode 11 are connected to a connection point of the transistor 2 and the output diode 3, and a second end is connected to the other end of the first resonance capacitor 8. One end of the diode 12 is connected, the other end of the second diode 12 is connected to the connection point of the output diode 3 and the output capacitor 5, and one end of the second resonance capacitor 14 is connected to the other end of the first diode 11. Connected to the connection point of DC power supply 1 and transistor 2
Is connected between the other end of the first diode 11 and the other end of the first resonance capacitor 8. Are connected in series.
In the chopper type DC-DC converters of FIGS. 9 and 10, the first and second resonance capacitors 8 and 14 and the resonance reactor 10 perform zero-voltage and zero-current switching when the transistor 2 is turned off and on, so that switching loss occurs. Is reduced. The spike-like surge voltage and surge current generated when the transistor 2 is turned off and turned on are the first and second surge voltages.
Are absorbed by the resonance action of the resonance capacitors 8 and 14 and the resonance reactor 10 to reduce the surge voltage, surge current and noise when the transistor 2 is turned on and off. In the chopper type DC-DC converter shown in FIGS. 11 and 12, a current limiting reactor 21 is connected in series with the output diode 3 of the chopper type DC-DC converter shown in FIGS. 9 and 10, respectively. In the chopper type DC-DC converter shown in FIGS. 11 and 12, the reverse recovery current flowing through the output diode 3 is reduced by the self-inducing action of the current limiting reactor 21 due to the recovery characteristic of the output diode 3 when the transistor 2 is turned on. Thus, the switching loss and the noise are further reduced as compared with the case of FIGS.

[0007]

By the way, in the chopper type DC-DC converter shown in FIGS. 9 and 10, when the output diode 3 is a general rectifier diode having a long reverse recovery time, when the transistor 2 is turned on. There is a drawback that a recovery current flows in the output diode 3 in the reverse direction, causing switching loss and noise. Also,
In the chopper type DC-DC converter shown in FIGS. 11 and 12, switching loss and noise caused by the recovery current flowing through the output diode 3 are reduced by the current limiting reactor 21.
However, there is a disadvantage that the number of parts is increased and the regulation characteristics are deteriorated. In particular, since the current limiting reactor 21 is a wound-type element, its size and weight are large, and reduction of large and heavy parts such as the reactor is extremely important in reducing the size, weight, and cost of the DC-DC converter. Is an important task.

Accordingly, an object of the present invention is to provide a chopper type DC-DC converter capable of reducing switching loss, surge voltage, current and the like with a small number of parts.

[0009]

According to the present invention, there is provided a chopper type DC-DC converter comprising: a DC power supply; a switching element having one main terminal connected to one end of the DC power supply;
An output rectifier connected between the other main terminal of the switching element and the other end of the DC power supply, a reactor having one end connected to a connection point between the switching element and the output rectifier, and An output capacitor connected between the other end and the other end of the DC power supply, and a load connected in parallel with the output capacitor, and the voltage of the DC power supply is controlled by turning on and off the switching element. A lower voltage DC output is provided to the load. In this chopper type DC-DC converter, a resonance reactor connected between the switching element and the output rectifier, and a first rectifier connected at one end to a connection point between the switching element and the resonance reactor. An element, a first resonance capacitor having one end connected to a connection point between the resonance reactor and the output rectifying element, and a connection between the other end of the first resonance capacitor and the other end of the DC power supply. And a second rectifier connected between the other end of the first rectifier and one end of the DC power supply.
, And a third rectifier connected between the other end of the first rectifier and the other end of the first capacitor, and the switching element is turned off. When the first resonance capacitor is discharged, the second resonance capacitor is charged in a sine wave shape, and when the switching element is turned on, the second resonance capacitor is discharged. The discharge is caused, and the first and second resonance capacitors and the resonance reactor resonate, so that a resonance current flows through the switching element. In practice, the DC power supply is composed of a rectifier circuit that converts an AC voltage of the AC power supply into a DC voltage.

[0010] Another chopper type DC-
The DC converter includes a DC power supply, a switching element having one main terminal connected to one line of the DC power supply and the other main terminal connected to the other line of the DC power supply, the DC power supply and the switching element. A reactor connected to the switching element, an output rectifier having one end connected to one main terminal of the switching element, and an output rectifying element connected between the other end of the output rectifying element and the other line of the DC power supply. Output capacitor, and a load connected in parallel with the output capacitor.
By performing the off control, a DC output of a voltage higher than the voltage of the DC power supply is supplied to the load. In this chopper type DC-DC converter, a resonance reactor connected between one main terminal of the switching element and one end of the output rectifier element, and one end is connected to a connection point of the switching element and the resonance reactor. A connected first rectifying element, one end connected to a connecting point between the resonance reactor and the output rectifying element, and one end connected to the other end of the first resonant capacitor. A second rectifier element having the other end connected to a connection point between the output rectifier element and the output capacitor; and a second rectifier element connected between the other end of the first rectifier element and the other line of the DC power supply. And a third capacitor connected between the other end of the first rectifying element and the other end of the first resonance capacitor.
When the switching element is turned off, the first resonance capacitor is discharged and the second resonance capacitor is charged in a sine wave shape, and the switching element is turned off. When turned on, the second resonance capacitor is discharged, and the first and second resonance capacitors and the resonance reactor resonate, so that a resonance current flows through the switching element. Actually, the DC power supply is composed of a rectifier circuit that converts an AC voltage of an AC power supply into a DC voltage, and the reactor is connected to an AC input side or a DC output side of the rectifier circuit.

When the switching element changes from the ON state to the OFF state, the first resonance capacitor is discharged and the second resonance capacitor is charged in a sine wave shape. Accordingly, the voltage at both ends of the switching element rises in a sine wave form from 0 V, so that zero-voltage switching when the switching element is turned off is achieved, and the switching loss when the switching element is turned off can be reduced. When the switching element changes from the off state to the on state, the second resonance capacitor is discharged, and the first and second resonance capacitors and the resonance reactor resonate, so that a resonance current flows through the switching element. This allows the current of the switching element to increase linearly from 0, thereby achieving zero current switching when the switching element is turned on, and reducing switching loss when the switching element is turned on. Therefore, the switching loss at the time of the ON / OFF operation of the switching element can be reduced, and the spike surge voltage and current can be reduced by the resonance action of the resonance capacitor and the resonance reactor. Furthermore, at the time of turning on of the switching element, the current of the output rectifying element gradually decreases due to the self-induction action of the resonance reactor, so that the reverse recovery current flowing through the output rectifying element at the time of turning on of the switching element is reduced. . For this reason, the current limiting reactor required conventionally is not required, and the number of components can be reduced, and the switching loss and noise due to the recovery characteristics of the output diode 3 when the switching element is turned on can be further reduced.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a chopper type D according to the present invention will be described.
Two embodiments of the C-DC converter will be described with reference to FIGS. However, in FIGS. 1 and 3, the same parts as those shown in FIGS. 9 and 10 are denoted by the same reference numerals, and the description thereof will be omitted. Chopper type D according to the present invention
FIG. 1 shows an embodiment in which a C-DC converter is applied to a step-down converter. That is, the step-down chopper type DC-DC converter shown in FIG. 1 is obtained by changing the connection position of the resonance reactor 10 between the transistor 2 and the output diode 3 in the step-down chopper type DC-DC converter shown in FIG. . Here, the resonance reactor 10 has a much smaller inductance than the reactor 4. The output diode 3 may be a general rectifying diode having a long reverse recovery time. Other configurations are the same as those of the step-down chopper type DC-DC converter shown in FIG.

In the configuration shown in FIG. 1, when the transistor 2 is turned on before t ₁ as shown in FIG. 2A, the transistor 2 is turned on as shown in FIGS. 2B and 2D.
Load 6 through resonance reactor 10 and reactor 4
Current I is flowing to At this time, as shown in FIG. 2 (G), the first resonance capacitor 8 is charged to the voltage E of the DC power supply 1 with the polarity shown in FIG. As shown in FIG. 2 (A), the control pulse signal voltage V _B that is applied from the control circuit 7 at t ₁ to the base terminal of the transistor 2 is made of a high level to a low level, the OFF state transistor 2 from the on state Then, the first diode 11 is forward-biased, and as shown in FIG. 2B, the current I _TR flowing through the transistor 2, that is, the current I of the load 6 immediately changes to the current flowing through the second resonance capacitor 14. Switch. At this time, as shown in FIG. 2 (D), together with the current I _L flowing through the resonant reactor 10 is reduced to a cosine wave, through the reactor 4 from the second diode 12 is forward biased first resonance capacitor 8 Discharge to the load 6 side. Therefore, as shown in FIGS. 2E and 2G, the current I _C1 of the first resonance capacitor 8 increases sinusoidally from 0, and the voltage V _C1 across the first resonance capacitor 8 increases. From the voltage E of the DC power supply 1, the voltage drops in a cosine waveform. Along with this, the second resonance capacitor 14 is charged in a sine wave form from 0 V, and as shown in FIG.
The voltage V _C2 at both ends of No. 4 rises in a sine wave form from 0V. As a result, as shown in FIG.
Of the voltage _VTR at both ends increases in a sine wave form from 0V.
Therefore, when the transistor 2 is turned off, zero voltage switching is performed in which the overlap between the voltage waveform and the current waveform is small.

As shown in FIGS. 2 (G) and 2 (C), at t ₂ , the voltages V _C1 and V _C2 across the first and second resonance capacitors 8 and 14 are 0 V and the voltage of the DC power supply 1, respectively. E
, The output diode 3 is forward-biased and becomes conductive, and as shown in FIGS. 2E and 2F, the current I _C1 flowing through the first resonance capacitor 8 is changed to the output diode 3.
Is switched to the current I _D flowing through. At the same time, FIG.
Current I _L 0 of the resonant reactor 10 as shown in (D)
Becomes At this time, the voltage V _TR across the transistor 2 is equal to the voltage E of the DC power supply 1 as shown in FIG. When the transistor 2 is off, the current I
Flows from the output diode 3 to the reactor 4.

As shown in FIG. 2A, at t ₃ , the control pulse signal voltage V _B applied from the control circuit 7 to the base terminal of the transistor 2 changes from a low level to a high level,
When the transistor 2 changes from the off state to the on state, FIG.
As shown in (H), the voltage V _TR across the transistor 2 immediately drops to 0V. At this time, the DC power supply 1 is connected to the resonance reactor 10 while the output diode 3 is conducting.
Since the voltage E is applied, increases linearly from current I _L 0 of the resonant reactor 10 as shown in FIG. 2 (D),
Energy is stored in the resonance reactor 10. When the current I _L of the resonant reactor 10 is equal to the current I in the load 6 at t _4, the second resonance capacitor 1
4 starts discharging, the first and second resonance capacitors 8 and 14 and the first resonance reactor 10 resonate, and the second resonance capacitor 14, the transistor 2, the resonance reactor 10, and the first A resonance current flows through the path of the resonance capacitor 8 and the third diode 16. Therefore, the resonance current flows through the resonance reactor 10 while being superimposed on the current supplied from the DC power supply 1. At this time, the current I _C1 flowing through the first resonance capacitor 8 increases in a sine wave form from 0 as shown in FIG. 2 (E), and the first resonance capacitor 8 is charged. As shown in ()), the voltage V _C1 across the first resonance capacitor 8 rises in a sine wave form from 0V. At the same time, the second resonance capacitor 1
The voltage V _C2 at both ends of C4 drops from the voltage E in a cosine wave as shown in FIG. Thereby, the transistor 2
The current I _TR is gradually linearly increases from 0 as shown in FIG. 2 (B). Therefore, when the transistor 2 is turned on, zero current switching is performed with little overlap between the voltage waveform and the current waveform.

On the other hand, the current _ID flowing through the output diode 3 is caused by the self-inducing action of the resonance reactor 10 as shown in FIG.
As shown in (F), the current decreases linearly, becomes 0 at t ₄ , and when the output diode 3 is turned off, the current I of the load 6 becomes the transistor 2 and the resonance reactor 1.
Current flowing to the 0 I _TR, I switched to I _L. At this time, since the above-described resonance current is superimposed and flows through the transistor 2 and the resonance reactor 10, the transistor 2
And the currents I _TR and I _L of the resonance reactor 10 are shown in FIG.
And t ₄ subsequent changes sinusoidally as shown in (D).
When the current I _L of the resonant reactor 10 is equal to the current I in the load 6, as shown in FIG. 2 (D) at t _5,
The voltages V _C1 and V _C2 across the first and second resonance capacitors 8 and 14 become the voltages E and 0 V of the DC power supply 1 as shown in FIGS. 2 (G) and 2 (C), respectively. At this time, the current I _{TR of the} transistor 2 becomes equal to the current I of the load 6 as shown in FIG. Therefore, t ₅ since the transistor 2 from the DC power source 1, a current I flows through the resonant reactor 10 and the reactor 4 to the load 6.

FIG. 3 shows an embodiment in which the chopper type DC-DC converter of the present invention is applied to a boost converter. That is, the step-up chopper type DC-DC shown in FIG.
The converter is a step-up chopper type DC-DC shown in FIG.
The connection position of the resonance reactor 10 in the converter is changed between the collector terminal of the transistor 2 and the anode terminal of the output diode 3 as in the embodiment shown in FIG. Here, the same reactor as the embodiment shown in FIG. 1 is used as the resonance reactor 10. Further, as the output diode 3, a general rectifying diode having a long reverse recovery time may be used as in the embodiment shown in FIG. The other configuration is the step-up chopper type DC-DC shown in FIG.
Same as converter.

In the configuration shown in FIG. 3, when the transistor 2 is turned on before t ₁ as shown in FIG. 4A, the reactor 4 and the resonance Current I in the path of reactor 10 and transistor 2
₀ is flowing. At this time, as shown in FIG.
The resonance capacitor 8 is charged to the terminal voltage, i.e. the output voltage E ₀ of the load 6 with the polarity shown in FIG. FIG. 4 (A)
As shown in FIG. 7, the control pulse signal voltage V _B applied to the base terminal of the transistor 2 from the control circuit 7 at t ₁ .
From the high level to the low level and the transistor 2 changes from the on state to the off state, as shown in FIG. 2B, the current I _TR flowing through the transistor 2, that is, the current I _{0 of the} reactor 4 is immediately changed to the first level. To the current flowing through the second resonance capacitor 14 through the diode 11. At this time, as shown in FIG. 4 (D), together with the current I _L flowing through the resonant reactor 10 is reduced to a cosine wave, discharge from the first resonance capacitor 8 to the second diode 12 through the load 6 side Go. Therefore, as shown in FIGS. 4E and 4G, the current I _C1 of the first resonance capacitor 8 increases in a cosine wave form from 0, and the voltage V _C1 across the first resonance capacitor 8 increases. The output voltage E ₀ drops in a cosine wave shape. Accordingly, the voltage of the second resonance capacitor 14 becomes 0V.
, The voltage V _C2 across the second resonance capacitor 14 rises sinusoidally from 0 V, as shown in FIG. 4C. Thus, as shown in FIG. 4H, the voltage V _TR across the transistor 2 rises in a sine wave form from 0V. Therefore, when the transistor 2 is turned off, zero voltage switching is performed in which the overlap between the voltage waveform and the current waveform is small.

As shown in FIGS. 4G and 4C, at t ₂ , the voltages V _C1 and V _C2 across the first and second resonance capacitors 8 and 14 become 0 V and the output voltage E ₀ , respectively. Then, the output diode 3 is forward-biased and becomes conductive, and the current I _C1 flowing through the first resonance capacitor 8 as shown in FIGS. 4 (E) and 4 (F) is shown in FIG. 4 (F). To the current _ID flowing through the output diode 3 as described above. At this time, the voltage V _TR across the transistor 2 is equal to the output voltage E ₀ as shown in FIG. When the transistor 2 is off, the current I _{0 of the} reactor 4 flows to the load 6 through the output diode 3.

As shown in FIG. 4A, at t ₃ , the control pulse signal voltage V _B applied from the control circuit 7 to the base terminal of the transistor 2 changes from a low level to a high level.
When the transistor 2 changes from the off state to the on state, FIG.
As shown in (H), the voltage V _TR across the transistor 2 immediately drops to 0V. At this time, the output voltage E is applied to the resonance reactor 10 during the conduction period of the output diode 3.
Since ₀ is applied, increases linearly from current I _L 0 of the resonant reactor 10 as shown in FIG. 4 (D), energy is stored in the resonant reactor 10. And t ₄
When the current I _L of the resonance reactor 10 becomes equal to the current I _{0 of the} reactor 4, the second resonance capacitor 14 starts discharging, and the first and second resonance capacitors 8, 14 and the first resonance capacitor When the resonance reactor 10 resonates, a resonance current flows through a path of the second resonance capacitor 14, the third diode 16, the first resonance capacitor 8, the resonance reactor 10, and the transistor 2. Therefore, the resonance current flows through the resonance reactor 10 while being superimposed on the current supplied from the load 6 side. At this time, the current I _C1 flowing through the first resonance capacitor 8 increases in a sine wave form from 0 as shown in FIG.
Is charged, and as shown in FIG. 4 (G), the voltage V _C1 across the first resonance capacitor 8 increases in a sine wave form from 0V. At the same time, the second resonance capacitor 14
The voltage V _C2 at both ends of the voltage E falls in a cosine wave form from the voltage E as shown in FIG. As a result, the current I _TR of the transistor 2 linearly increases from 0 as shown in FIG. Therefore, when the transistor 2 is turned on, zero current switching is performed with little overlap between the voltage waveform and the current waveform.

On the other hand, the current _ID flowing through the output diode 3 is caused by the self-inducing action of the resonance reactor 10 as shown in FIG.
As shown in (F), the current decreases linearly, becomes 0 at t ₄ , and when the output diode 3 is turned off, the current I _{0 of the} reactor 4 becomes the current I ₀ flowing through the transistor 2 and the resonance reactor 10. _TR, I switched to I _L. At this time, the transistor 2 and the resonance reactor 1
0, the above-mentioned resonance currents are superimposed and flow, so that the currents I _TR and I _{L of the} transistor 2 and the resonance reactor 10 are
FIG 4 (B) and (D) as shown in t ₄ subsequent changes sinusoidally. Then, the resonance reactor 10 at t ₅
When the current I _L is equal to the current I ₀ of the reactor 4 as shown in FIG. 4 (D), the voltage V _C1, V _C2 across the first and second resonance capacitor 8 and 14 in FIG. 4 (G ) And (C), the output voltages become E ₀ and 0 V, respectively. At this time, the current I _{TR of the} transistor 2 becomes equal to the current I _{0 of the} reactor 4 as shown in FIG. Therefore,
t ₅ after the reactor 4 from the DC power source 1, a current flows I ₀ in the path of the resonant reactor 10 and the transistor 2.

As described above, in the embodiment shown in FIGS. 1 and 3, zero voltage and zero current switching are achieved when the transistor 2 is turned off and turned on, so that the switching loss of the transistor 2 can be reduced. The spike-shaped surge current and surge voltage generated when the transistor 2 is turned on and off are absorbed by the resonance between the first and second resonance capacitors 8 and 14 and the first resonance reactor 10, and Since the rising of the voltage and current waveforms of the transistor 2 becomes gentle, the surge voltage, surge current, and noise during the on / off operation of the transistor 2 can be reduced.
Further, when the transistor 2 is turned on, the reverse recovery current flowing through the output diode 3 is absorbed by the self-induction action of the resonance reactor 10, and the current of the output diode 3 gradually decreases. At this time, the reverse recovery current flowing through the output diode 3 is reduced. For this reason, when the output diode 3 is a general rectifier diode having a long reverse recovery time, the current limiting reactor conventionally required is unnecessary, and the number of components can be reduced. Therefore, switching loss, surge voltage, current, and the like can be reduced with a small number of components, and switching loss and noise due to the recovery characteristics of the output diode 3 when the transistor 2 is turned on can be further reduced.

In the embodiment shown in FIG. 3, an example is shown in which the resonance reactor 10 is connected between the connection point between the anode terminal of the reactor 4 and the output diode 3 and the collector terminal of the transistor 2. As shown, a resonance reactor 10 may be connected between a connection point between the collector terminal of the reactor 4 and the transistor 2 and an anode terminal of the output diode 3. In the case of the circuit of the embodiment shown in FIG. 5, when the transistor 2 is in the off state, the current I _{0 of the} reactor 4 flows through the resonance reactor 10 and the output diode 3 to the load 6, and when the transistor 2 is turned on from this state, the reactor 4 In addition, since the current flowing through the resonance reactor 10 changes from I ₀ , the current I _TR flowing through the transistor 2 rises from 0. Therefore, even in the case of the circuit of the embodiment shown in FIG. 5, as in the case of the circuit of the embodiment shown in FIG. 3, when the transistor 2 is turned on, zero current switching with little overlap between the voltage waveform and the current waveform is obtained. Therefore, in the embodiment shown in FIG. 5, the same switching loss and noise reduction effects as those of the embodiment shown in FIG. 3 can be obtained.

The embodiments of the present invention are not limited to the above embodiments, and various modifications are possible. For example, in each of the above embodiments, an example in which a junction bipolar transistor is used as a switching element has been described.
Other switching elements such as T (MOS field effect transistor), J-FET (junction field effect transistor), SCR (reverse blocking three-terminal thyristor) may be used. Also, in practice, a single-phase rectifier circuit that converts a single-phase AC voltage of a single-phase commercial AC power supply to a DC voltage or a three-phase rectifier that converts a three-phase AC voltage of a three-phase commercial AC power supply to a DC voltage. In many cases, the circuit is used as the DC power supply 1, but of course, a dry cell, a battery, or the like can be used as the DC power supply 1. Furthermore, when a single-phase or three-phase rectifier circuit is used as the DC power supply 1 in the embodiments shown in FIGS. 3 and 5, a reactor 4 may be connected to the AC input side of the rectifier circuit.

[0025]

According to the present invention, large and heavy parts such as a current limiting reactor required conventionally can be eliminated and the number of parts can be reduced, and switching loss and noise can be reduced. A low-cost, low-loss, low-noise chopper-type DC-DC converter can be realized. Since a general rectifying diode having a long reverse recovery time can be used as the output rectifying element, the first recovery diode (FR) having a short reverse recovery time is not necessarily required.
There is an advantage that there is no need to use D) and there is no restriction on the electric components used.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of a step-down chopper type DC-DC converter according to the present invention.

FIG. 2 is a waveform chart showing voltages and currents of respective parts of the circuit of FIG.

FIG. 3 is an electric circuit diagram showing an embodiment of a step-up chopper type DC-DC converter according to the present invention.

FIG. 4 is a waveform chart showing the voltage and current of each part of the circuit of FIG.

FIG. 5 is an electrical diagram showing a modified embodiment of the circuit of FIG. 3;

FIG. 6 is an electric circuit diagram showing a conventional step-down chopper type DC-DC converter.

FIG. 7 is an electric circuit diagram showing a conventional step-up chopper type DC-DC converter.

FIG. 8 is a waveform diagram showing an overlapping portion between the switching voltage waveform and the switching current waveform of the circuits of FIGS. 6 and 7;

9 is an electric circuit diagram showing an example of improvement of switching characteristics in the circuit of FIG.

FIG. 10 is an electric circuit diagram showing an example of improvement of switching characteristics in the circuit of FIG. 7;

FIG. 11 is an electrical diagram illustrating a modified embodiment of the circuit of FIG. 9;

FIG. 12 is an electrical diagram illustrating a modified embodiment of the circuit of FIG.

[Explanation of symbols]

1. . . DC power supply, 2. . . 2. transistor (switching element); . . Output diode (output rectifier),
4. . . Reactor, 5. . . Output capacitor,
6. . . Load, 7. . . Control circuit, 8. . . 10. first resonance capacitor; . . Reactor for resonance, 1
1. . . First diode (first rectifying element), 1
2. . . Second diode (second rectifier), 1
4. . . 12. second resonance capacitor; . . 13. third diode (third rectifier); . . Current limiting reactor

Claims (4)

[Claims] 1. A DC power supply, a switching element having one main terminal connected to one end of the DC power supply, and an output connected between the other main terminal of the switching element and the other end of the DC power supply. A rectifier, a reactor having one end connected to a connection point between the switching element and the output rectifier, an output capacitor connected between the other end of the reactor and the other end of the DC power supply, and the output capacitor. And a load connected in parallel with the chopper type DC-DC converter that supplies a DC output of a voltage lower than the voltage of the DC power supply to the load by controlling on / off of the switching element. A resonance reactor connected between the element and the output rectifier, and one end connected to a connection point between the switching element and the resonance reactor. The first was continued 1
Rectifier element, a first resonance capacitor having one end connected to a connection point between the resonance reactor and the output rectifier element, and a second capacitor connected between the other end of the first resonance capacitor and the other end of the DC power supply. A second rectifying element connected to the first
A second resonance capacitor connected between the other end of the rectifier element and one end of the DC power supply, and between the other end of the first rectifier element and the other end of the first resonance capacitor. And a third rectifier element connected to the first and second rectifier elements, wherein when the switching element is turned off, the first resonance capacitor is discharged and the second resonance capacitor is charged in a sine wave shape. When the switching element is turned on, the second resonance capacitor is discharged, and the first and second resonance capacitors and the resonance reactor resonate. Chopper type DC-D characterized by current flowing
C converter. 2. The chopper-type DC-DC converter according to claim 1, wherein the DC power supply includes a rectifier circuit that converts an AC voltage of the AC power supply into a DC voltage. 3. A DC power supply, a switching element having one main terminal connected to one line of the DC power supply and the other main terminal connected to the other line of the DC power supply, A reactor connected between the switching element, an output rectifying element having one end connected to one main terminal of the switching element, and an output rectifying element connected between the other end of the output rectifying element and the other line of the DC power supply. An output capacitor connected thereto, and a load connected in parallel with the output capacitor, and a DC output of a voltage higher than the voltage of the DC power supply is supplied to the load by controlling on / off of the switching element. Chopper type DC-D
In the C converter, a resonance reactor connected between one main terminal of the switching element and one end of the output rectifier, and a first reactor connected at one end to a connection point between the switching element and the resonance reactor. Rectifying element and a first end connected to a connection point between the resonance reactor and the output rectifying element.
A rectifying element, one end of which is connected to the other end of the first resonance capacitor and the other end of which is connected to a connection point of the output rectifying element and the output capacitor; A second resonance capacitor connected between the other end of the element and the other line of the DC power supply, and a second resonance capacitor connected between the other end of the first rectifying element and the other end of the first resonance capacitor; And a third rectifier element connected to the first and second rectifier elements, wherein when the switching element is turned off, the first resonance capacitor is discharged and the second resonance capacitor is charged in a sine wave shape. When the switching element is turned on, the second resonance capacitor is discharged, and the first and second resonance capacitors and the resonance reactor resonate to share with the switching element. Chopper DC-DC converter, wherein a current flows. 4. The DC power supply is configured by a rectifier circuit that converts an AC voltage of an AC power supply into a DC voltage, and the reactor is connected to an AC input side or a DC output side of the rectifier circuit. 4. The chopper type DC-DC converter according to 1.