JP3055121B2 - Chopper type DC-DC converter - Google Patents

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 to 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 connected to the transistor 2 and the output diode 3 A reactor 4 connected to the point, an output capacitor 5 connected to 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 base terminal of the transistor 2. And a control circuit 7 for applying a control pulse signal to control on / off of the transistor 2. This step-down chopper type DC-DC
In the 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)
Is an output diode 3 as an output rectifying element connected to the collector terminal of the transistor 2, an output capacitor 5 connected to the cathode terminal (the other end) of the output diode 3 and the negative line of the DC power supply 1, and an output capacitor. The control circuit 7 includes a load 6 connected in parallel with the control circuit 5, and a control circuit 7 for applying a control pulse signal to the base terminal of the transistor 2 to perform on / off control of the transistor 2. In this step-up chopper type DC-DC converter, the transistor 2 is turned on.
By performing the OFF control, a DC output of a voltage higher than the voltage of the DC power supply 1 is supplied to the load 6.

[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
The other end of the resonance capacitor 14 is connected, and the other end of the first diode 11 and the other end of the first resonance capacitor 8 are connected to the resonance reactor 10 and a third diode as a third rectifier. 16 are connected in series. In the chopper type DC-DC converter 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 is reduced. Further, a spike-shaped surge voltage and surge current generated when the transistor 2 is turned off and turned on are absorbed by the resonance action between the first and second resonance capacitors 8 and 14 and the resonance reactor 10, and the transistor 2 is turned on. -Surge voltage, surge current and noise during off operation are reduced. The chopper type DC-DC converters shown in FIGS. 11 and 12 correspond to the chopper type D-DC converter shown in FIGS. 9 and 10, respectively.
A current limiting reactor 21 is connected in series with the output diode 3 of the C-DC converter. 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]

A chopper type DC-DC converter according to the present invention comprises a DC power supply (1) and a DC power supply (1).
Switching element with one main terminal connected to one end of
(2), the other main terminal of the switching element (2) and the DC power supply
An output rectifier (3) connected to the other end of (1), a reactor (4) having one end connected to a connection point of the switching element (2) and the output rectifier (3), and a reactor (4) And an output capacitor (5) connected to the other end of the DC power supply (1), and a load (6) connected in parallel with the output capacitor (5), and the switching element (2) is turned on.・ By performing the off control, a DC output of a voltage lower than the voltage of the DC power supply (1) is supplied to the load (6). In this chopper type DC-DC converter, the switching element (2), the output rectifying element (3), and the reactor
A resonance reactor (10) connected to the connection point of (4),
One end is connected to a connection point between the switching element (2) and the resonance reactor (10), and one end is connected to a connection point between the resonance reactor (10) and the output rectification element (3). A connected first resonance capacitor (8), a second rectifier element (12) connected to the other end of the first resonance capacitor (8) and the other end of the DC power supply (1), A second resonance capacitor (14) connected to the other end of the first rectifier (11) and one end of the DC power supply (1); A third rectifier (1) connected to the other end of the resonance capacitor (8)
6), the first resonance capacitor (8) is discharged when the switching element (2) is turned off, and the second resonance capacitor (14) is charged in a sine wave shape when the switching element (2) is turned off.
When (2) is turned on, the second resonance capacitor (14) is discharged, and the first resonance capacitor (8), the second resonance capacitor (14), and the resonance reactor (10) resonate. As a result, a resonance current flows through the switching element (2). The DC power supply (1) includes a rectifier circuit that converts an AC voltage of an AC power supply into a DC voltage.

[0010] Another chopper type DC-
The DC converter has a DC power supply (1), one main terminal connected to one line of the DC power supply (1) via a reactor (4), and the other main terminal connected to the other line of the DC power supply (1). A switching element (2), an output rectifying element (3) having one end connected to a connection point of one main terminal of the reactor (4) and the switching element (2), and an output rectifying element (3). An output capacitor (5) connected to the other end and the other line of the DC power supply (1), and a load (6) connected in parallel with the output capacitor (5), and the switching element (2) is turned on. -By performing the off control, a DC output of a voltage higher than the voltage of the DC power supply (1) is supplied to the load (6). This chopper type DC-DC
In the converter, a resonance reactor (10) connected to one main terminal of the switching element (2) and one end of the output rectifier (3), and a connection point of the switching element (2) and the resonance reactor (10). First rectifier element (11) having one end connected to
A first resonance capacitor (8) having one end connected to a connection point between the resonance reactor (10) and the output rectifier (3);
A second rectifying element (12) having one end connected to the other end of the first resonance capacitor (8) and the other end connected to a connection point between the output rectifying element (3) and the output capacitor (5); First rectifier
A second resonance capacitor (14) connected to the other end of (11) and the other line of the DC power supply (1), and a first rectifier (11)
And a third rectifier element (16) connected to the other end of the first resonance capacitor (8) and the other end of the first resonance capacitor (8).
When (2) is off, the first resonance capacitor (8) is discharged, and the second resonance capacitor (14) is charged in a sine wave shape. When the switching element (2) is on, the second resonance capacitor (8) is discharged. (14) is discharged and the first resonance capacitor
(8), the second resonance capacitor (14) and the resonance reactor (10) resonate, and a resonance current flows through the switching element (2). The DC power supply (1) includes a rectifier circuit that converts an AC voltage of an AC power supply into a DC voltage, and a reactor (4) is connected to an AC input side or a DC output side of the rectifier circuit.

When the switching element (2) changes from the on state to the off state, the first rectifying element (11) is forward-biased,
The current flowing through the switching element (2) is immediately switched to the current flowing through the second resonance capacitor (14), the first resonance capacitor (8) is discharged, and the second resonance capacitor (14) is sinusoidally discharged. It is charged in a wave. Thus, the voltage across the switching element (2) rises in a sine wave form from 0 V, so that zero voltage switching is achieved when the switching element (2) is turned off, and switching loss at the time of turning off can be reduced. When the switching element (2) changes from the off state to the on state, the second resonance capacitor (14) is discharged, and the first resonance capacitor (8) and the second resonance capacitor (14) are connected. The resonance reactor (10) resonates and a resonance current flows through the switching element (2). Thereby, the switching element (2)
Current increases linearly from 0, zero current switching is achieved when the switching element (2) is turned on, and switching loss at the time of turn-on can be reduced. Therefore, the switching loss at the time of the ON / OFF operation of the switching element (2) can be reduced, and the first resonance capacitor (8), the second resonance capacitor (14), and the resonance reactor (10) can be reduced. Can reduce spike-shaped surge voltage and current. Furthermore, when the switching element (2) is turned on, the output rectifying element is generated by the self-inducing action of the resonance reactor (10).
Since the current of (3) gradually decreases, the switching element
The reverse recovery current flowing through the output rectifier (3) at the time of turning on (2) 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 rectifying element (3) can be further reduced when the switching element (2) is turned on.

[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 configured by connecting the resonance reactor 10 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
This is the same as 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.
As in the converter shown in FIG. 1, the converter is such that the resonance reactor 10 in the step-up chopper type DC-DC converter shown in FIG. 10 is connected to the collector terminal of the transistor 2 and the anode terminal of the output diode 3. Here, the same reactor as the embodiment shown in FIG. 1 is used as the resonance reactor 10. The output diode 3
As in the embodiment shown in FIG. 1, a general rectifying diode having a long reverse recovery time may be used. Other configurations are the same as those of the step-up chopper type DC-DC converter shown in FIG.

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, the resonance reactor 1 is connected between the connection point of the anode terminal of the reactor 4 and the output diode 3 and the collector terminal of the transistor 2.
5, the resonance reactor 10 is connected between the connection point between the collector terminal of the reactor 4 and the collector terminal of the transistor 2 and the anode terminal of the output diode 3 as shown in FIG.
May be connected. In the case of the circuit of the embodiment shown in FIG.
When the transistor 2 is in the off state, the current I _{0 of the} reactor 4 flows to the load 6 through the resonance reactor 10 and the output diode 3, and when the transistor 2 is turned on from this state, the current flowing in the reactor 4 and the resonance reactor 10 becomes I _0. The current I _TR flowing through the transistor 2 rises from 0 because it changes more. 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

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02M 3/155

Claims (4)

(57) [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 rectifying element connected to 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 rectifying element,
An output capacitor connected to the other end of the reactor and the other end of the DC power supply, and a load connected in parallel with the output capacitor, the on / off control of the switching element to control the DC power supply A chopper-type DC-DC converter that supplies a DC output of a voltage lower than a voltage to the load, wherein a resonance reactor connected to a connection point between the switching element, the output rectifying element, and the reactor, the switching element, and the A first rectifying element having one end connected to a connection point of the resonance reactor, a first resonance capacitor having one end connected to a connection point of the resonance reactor and the output rectification element, and A second rectifier connected to the other end of the capacitor for use and the other end of the DC power supply; and a second rectifier connected to the other end of the first rectifier and the DC power supply. A second resonance capacitor connected to one end of the source; and a third rectifier connected to the other end of the first rectifier and the other end of the first 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. When the switching element is turned on, the second resonance capacitor is discharged. A chopper type DC-DC converter, wherein the first resonance capacitor, the second resonance capacitor, and the resonance reactor resonate, and a resonance current flows through the switching element. 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 via a reactor and the other main terminal connected to the other line of the DC power supply, An output rectifying element having one end connected to a connection point between the reactor and one main terminal of the switching element; an output capacitor connected to the other end of the output rectifying element and the other line of the DC power supply; A chopper-type DC-DC converter that includes a capacitor and a load connected in parallel, and supplies a DC output of a voltage higher than the voltage of the DC power supply to the load by controlling on / off of the switching element. A resonance reactor connected to one main terminal of the element and one end of the output rectifier, the switching element and the resonance First a first rectifying element having one end connected to a connection point of the reactor, one end to the connection point of the resonant reactor and the output rectifying element connected 1
A second rectifying element having one end connected to the other end of the first resonance capacitor and the other end connected to a connection point between the output rectifying element and the output capacitor; A second resonance capacitor connected to the other end of the rectifying element and the other line of the DC power supply, and connected to the other end of the first rectifying element and the other end of the first resonance capacitor. A third rectifying element, the first resonance capacitor is discharged when the switching element is turned off, and the second resonance capacitor is charged in a sine wave shape when the switching element is turned off. When the second resonance capacitor is discharged, the first resonance capacitor, the second resonance capacitor, and the resonance reactor resonate, and a resonance current flows through the switching element. Chopper, characterized in DC-DC
converter. 4. The DC power supply according to claim 3, wherein the DC power supply includes 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. Chopper type DC-DC converter.