JP2001008445A - Chopper dc-dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce switching loss, surge voltage, current, etc., of a chopper DC-DC converter. SOLUTION: A chopper DC-DC converter is constituted, in such a way that when a main switching element 2 is switched to a turn-off state from a turn-on state, the current flowing to the element 2 is immediately switched to a current flowing into first and second capacitors 8 and 14 for resonance, and the first capacitor 8 gradually discharges. At the same time, the second capacitor 2 is gradually changed, and the voltage across the element 2 gradually rises from 0 V. Consequently, the switching loss of the main switching element 2 can be reduced, because zero-voltage switching(ZVS) is achieved, when the element 2 is turned off.

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, and particularly to a chopper type DC-DC converter having a small switching loss and high efficiency.

[0002]

2. Description of the Related Art A main switching element and a reactor are connected in series between a DC power supply and a load, and a rectifying element for main circulation is connected in a T-shape between a connection point between the main switching element and the reactor and the DC power supply. An output capacitor is connected in parallel with the load, one end of the rectifying element for main circulation is connected to one end of the output capacitor, and the on / off control of the main switching element controls the constant voltage different from the voltage of the DC power supply. 2. Description of the Related Art A chopper type DC-DC converter for supplying a DC output to a load has been widely used in power supply circuits of electronic devices and the like.

For example, a conventional step-down chopper type DC-DC converter shown in FIG. 12 has a DC power supply 1 and a main transistor as a main switching element having a collector terminal (one main terminal) connected to one end of the DC power supply 1. 2, a main reflux diode 3 as a main reflux rectifying element connected between the emitter terminal (the other main terminal) of the main transistor 2 and the other end of the DC power supply 1, a main transistor 2 and a main reflux current A reactor 4 connected to a connection point of the diode 3,
An output capacitor 5 connected between the reactor 4 and the other end of the DC power supply 1, a load 6 connected in parallel with the output capacitor 5, and a control pulse signal applied to the base terminal of the main transistor 2 And a control circuit 7 for controlling on / off of the control circuit 2. This step-down chopper type DC
In the −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 main transistor 2.

A conventional step-up chopper type DC-DC converter shown in FIG. 13 includes a DC power supply 1 and a reactor 4 connected to a positive line (one line) of the DC power supply 1.
A main transistor 2 having a collector terminal connected via the reactor 4 and an emitter terminal connected to the negative line (the other line) of the DC power supply 1, and a collector terminal of the main transistor 2 Main reflux diode 3 as a main reflux current rectifier
An output capacitor 5 connected between the main reflux diode 3 and the negative line of the DC power supply 1, a load 6 connected in parallel with the output capacitor 5, and a control pulse signal applied to the base terminal of the main transistor 2. The main transistor 2
And a control circuit 7 for controlling ON / OFF of the control signal. 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 turning on / off the main transistor 2.

The control circuit 7 shown in FIGS. 12 and 13 changes the time width of the control pulse signal applied to the base terminal of the main transistor 2 in proportion to the fluctuation of the terminal voltage of the load 6 to thereby control the main transistor 2. Control the on period of the
The DC power supplied to the load 6 is stabilized.

[0006]

By the way, in the chopper type DC-DC converter of FIGS. 12 and 13, when the main transistor 2 is turned on or off, as shown in FIG. V _CE and collector current waveform I _C of main transistor 2
However, there is a disadvantage that a large switching loss occurs due to the overlapping portion W. Further, since the collector-emitter voltage waveform V _CE and the collector current waveform I _C of the main transistor 2 rise steeply, there is a disadvantage that spike-shaped surge voltage V _sr , surge current I _sr and noise are generated. Therefore, an object of the present invention is to provide a chopper-type DC-DC converter that can reduce switching loss, surge voltage, current, and the like.

[0007]

DISCLOSURE OF THE INVENTION Chopper type DC of the present invention
In the DC converter, (A) a main switching element (2) and a main rectifying rectifier (3) are connected in series to a DC power supply (1), and a main rectifying element (3) and an output capacitor (5) are connected. ), Or (B) reactor (4)
The main switching element (2) and the main rectifying rectifier (3) are connected to the DC power supply (1) through the main rectifier (3).
And an output capacitor (5) in series. The output capacitor (5) is connected between the rectifying element (3) for main circulation and the load (6), and the on / off control of the main switching element (2) allows the voltage of the DC power supply (1) to be reduced. Supplies a DC output of a different voltage to the load (6). A first resonance capacitor (8) is connected to a connection point of the main switching element (2) and the main rectifying element (3), and the connection of the first resonance capacitor (8) and the main switching element (2). The first auxiliary reflux rectifying element (11) is connected to the point. A series circuit having a resonance reactor (10) and a resonance current rectifier (16) is connected between the first resonance capacitor (8) and the first auxiliary reflux rectifier (11). A second auxiliary reflux rectifier (12) is connected between the connection point of the resonance capacitor (8) and the series circuit and the connection point of the main reflux rectifier (3) and the output capacitor (5). . A second resonance capacitor (14) is connected between the connection point of the first auxiliary reflux rectifying element (11) and the series circuit and the connection point of the main switching element (2) and the DC power supply (1). . When the main switching element (2) is turned off, the first resonance capacitor (8) is discharged, and the second resonance capacitor (14) is gradually charged.
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).
Resonates and a resonance current flows through the main switching element (2).

In the preferred embodiment of the present invention, the second auxiliary reflux rectifier (12) is connected to the resonance reactor (10), and the second resonance capacitor (14) is connected to the resonance current rectifier (16). ). A current limiting reactor (21) is connected in series with the main reflux element (3) or the main switching element (2). A third connection between the connection point of the main reflux rectifying element (3) and the first resonance capacitor (8) and the connection point of the first auxiliary reflux rectifying element (11) and the main switching element (2). Auxiliary reflux rectifier
(22) and the third resonance capacitor (23) are connected in series, and the connection point of the third auxiliary reflux rectifier (22) and the third resonance capacitor (23) is connected to the main reflux rectifier (3). ) And the connection point of the output capacitor (5).
4) Connect.

One main terminal of the main switching element (2) is connected to one end of the DC power supply (1), and the main reflux rectifying element (3) is connected to the other main terminal of the main switching element (2) by the DC power supply (1). It is connected between the other end of 1). The reactor (4) is the connection point between the main switching element (2) and the main rectifying element (3) and the load.
(6). By performing on / off control of the main switching element (2), a DC output of a voltage lower than the voltage of the DC power supply (1) is supplied to the load (6).

The DC power supply (1) comprises an AC power supply (25) and a rectifier circuit (27) for converting an AC voltage of the AC power supply (25) into a DC voltage. The reactor (4) is connected to one line of the DC power supply (1), one main terminal of the main switching element (2) is connected via at least the reactor (4), and the other of the main switching element (2). A main terminal is connected to the other line of the DC power supply (1), and a main reflux rectifying element (3) is connected between one main terminal of the main switching element (2) and the load (6). By performing on / off control of the main switching element (2), a DC output of a voltage higher than the voltage of the DC power supply (1) is supplied to the load (6).

The DC power supply (1) comprises an AC power supply (26) and a rectifier circuit (28) for converting an AC voltage of the AC power supply (26) into a DC voltage, and an AC input side of the rectifier circuit (28). Alternatively, the reactor (4) is connected to the DC output side. The DC power supply (1) includes an AC power supply (26) and an AC-DC conversion switching element (29 to 3).
4) and a circulating current rectifying element (35 to 40) comprising a rectifying element integrally formed with the AC-DC converting switching element (29 to 34) or a rectifying element independently connected in parallel, and An AC-DC converter circuit (41) for converting an AC voltage of an AC power supply (26) into a DC voltage by controlling on / off of a DC conversion switching element (29-34); The reactor (4) is connected to the AC input side of (41), and the AC-DC converter circuit (41)
A power supply resonance capacitor (42) is connected between a pair of lines on the DC output side.

When the main switching element (2) is turned off while the main switching element (2) is on, the current flowing through the main switching element (2) immediately causes the first and second resonance capacitors (8, The current is switched to the current flowing in 14), and the first resonance capacitor (8) is gradually discharged. At the same time, the second resonance capacitor (14) is gradually charged, and the voltage across the main switching element (2) gradually increases from 0V. Thereby, the main switching element (2)
Since zero voltage switching (ZVS) is achieved at the time of turning off the switching element, the switching loss at the time of turning off the main switching element (2) can be reduced.

When the main switching element (2) is turned off from the on state, the first resonance capacitor is turned on.
(8) is discharged, and the second resonance capacitor (14) is gradually charged. With this, the main switching element
Since the voltage at both ends of (2) gradually rises from 0 V, zero voltage switching is achieved when the main switching element (2) is turned off, and switching loss when the main switching element (2) is turned off can be reduced. .

When the main switching element (2) is turned on from the off state, the second resonance capacitor (1) is turned on.
4) is discharged, the first and second resonance capacitors (14) and the resonance reactor (10) resonate, and a resonance current flows through the main switching element (2). As a result, the current of the main switching element (2) increases in a sine wave form from 0, so that zero current switching at the time of turning on the main switching element (2) is achieved, and the main switching element (2) is achieved.
The switching loss at the time of turn-on (2) can be reduced.

Therefore, the switching loss during the ON / OFF operation of the main switching element (2) can be reduced with a simple circuit configuration, and the first and second resonance capacitors can be reduced.
The spike-like surge voltage and current can be reduced by the resonance action of (8, 14) and the reactor for resonance (10). In addition, the current limiting reactor (21) is used as the main reflux rectifier.
(3) or when connected in series with the main switching element (2), after the main switching element (2) is turned on, the main current rectifying element
Since the current of (3) decreases linearly, when the main switching element (2) is turned on, the power supply voltage (in the case of a step-down converter) or the output voltage (in the case of a step-up Case) can be avoided.

Further, the connection point between the main rectifying element (3) and the first resonance capacitor (8) and the connection point between the first auxiliary rectifying element (11) and the main switching element (2) are set. A third auxiliary reflux rectifying element (22) and a third resonance capacitor (23) are connected in series between the third auxiliary reflux rectifying element (22) and the third resonance capacitor (23). When a fourth auxiliary reflux element (24) is connected between the connection point and the connection point of the main reflux rectifier (3) and the output capacitor (5), the main switching element (2) is turned off and turned on. Since the charge time and the discharge time of the second resonance capacitor (14) sometimes become long, the zero voltage and zero current switching at the time of turning off and turning on the main switching element (2) are more reliably performed, and the switching loss is further reduced. be able to.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a chopper type D according to the present invention will be described.
One embodiment of a C-DC converter will be described with reference to FIGS. However, FIGS. 1 and 3 show FIGS.
The same reference numerals are given to the same portions as those shown in FIG. The embodiment shown in FIG. 1 in which the chopper type DC-DC converter according to the present invention is applied to a step-down converter has a first resonance capacitor 8 connected to the connection point of the main transistor 2 and the main reflux diode 3 of FIGS. Is connected, and a first auxiliary reflux diode 11 is connected to a connection point between the first resonance capacitor 8 and the main transistor 2, so that the first auxiliary reflux diode 11 is connected between the first resonance capacitor 8 and the first auxiliary reflux diode 11. A resonance reactor 10 and a resonance current diode 16 are connected in series, and a first connection is made between a connection point of the first resonance capacitor 8 and the resonance reactor 10 and a connection point of the main reflux diode 3 and the output capacitor 5. The second auxiliary reflux diode 12 is connected, and the connection point of the first auxiliary reflux diode 11 and the resonance current diode 16 is connected to the main transistor 2 and the direct current. Second resonance capacitor 14 is connected between the connection point of the power supply 1.

In the above configuration, if the main transistor 2 is turned on before time t ₀ as shown in FIG. 2A, the main transistor 2 and the reactor 4 are turned on as shown in FIG.
The current I flows to the load 6 through. At this time, FIG.
As shown in FIG. 1, 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. 2A, at time t ₀ , the control circuit 7 sends the main transistor 2
Becomes a main control pulse signal voltage V _B that is applied to the base terminal of the high level to the low level, the main transistor 2 is turned off from the on state, the current flowing through the main transistor 2 as shown in FIG. 2 (B) I _TR , that is, the current I of the load 6 is immediately switched to the current flowing through the first resonance capacitor 8 and the second resonance capacitor 14. At this time, the first
2 gradually discharges, and the voltage V _C1 across the first resonance capacitor 8 linearly drops from the voltage E of the DC power supply 1 as shown in FIG. Along with this,
The second resonance capacitor 14 is gradually charged from 0 V, and as shown in FIG.
Voltage V _C2 across rises linearly from 0V to. This causes the voltage V _TR across the main transistor 2 to rise linearly from 0 V, as shown in FIG. Therefore, when the main transistor 2 is turned off, zero voltage switching is performed with little overlap between the voltage waveform and the current waveform.

As shown in FIGS. 2E and 2D, at time t ₁
When the voltages V _C1 and V _C2 across the first and second resonance capacitors 8 and 14 become 0 V and the voltage E of the DC power supply 1, respectively, the main reflux diode 3 becomes conductive and the first
And the current flowing through the second resonance capacitor 8 and 14 is switched to the current I _D flowing through the main wheeling diode 3 as shown in FIG. 2 (F). At this time, the voltage V _TR across the main transistor 2 is equal to the voltage E of the DC power supply 1 as shown in FIG. When the main transistor 2 is off, the current I of the load 6 flows from the main reflux diode 3 to the reactor 4.
Flows to

As shown in FIG. 2A, at time t ₂ , the main control pulse signal voltage V _B applied from the control circuit 7 to the base terminal of the main transistor 2 changes from a low level to a high level. As shown in FIG. 2 (C), the voltage V _TR across the main transistor 2 rapidly drops to 0V when the transistor is turned on from the off state. At the same time, the second resonance capacitor 14 starts discharging, and the first and second resonance capacitors 8 and 14 and the resonance reactor 10 are discharged.
Resonate, and a resonance current flows through the path of the second resonance capacitor 14, the main transistor 2, the first resonance capacitor 8, the resonance reactor 10, and the resonance current diode 16. Therefore, current I _L flowing through the resonant reactor 10 varies sinusoidally, as shown in FIG. 2 (G). At this time, the first resonance capacitor 8 is charged in a cosine waveform, and as shown in FIG. 2E, the voltage V _C1 across the first resonance capacitor 8 rises in a cosine waveform from 0 V,
The voltage V _C2 across the second resonance capacitor 14 is shown in FIG.
As shown in (D), the voltage drops from the voltage E in a cosine waveform. As a result, the current I _TR of the main transistor 2 increases in a sinusoidal manner from 0 as shown in FIG. 2 (B), so that when the main transistor 2 is turned on, zero-current switching with little overlap between the voltage waveform and the current waveform is achieved.

On the other hand, the current _ID flowing through the main reflux diode 3 is caused by the self-inducing action of the current limiting reactor 21 as shown in FIG.
As shown in (F), when the current decreases linearly and reaches 0 at time t ₃ , the current I of the load 6 flows into the current I _TR flowing through the main transistor 2.
Switch to As shown in FIG. 2 (G), the current I _L of the resonant reactor 10 at time t ₄ becomes zero, the voltage across V _C1 of the first and second resonance capacitor 8, 14, V _C2
However, as shown in FIGS. 2 (E) and 2 (D),
Voltage E and 0V. At this time, the main transistor 2
Current I _TR of is equal to the current I in the load 6, as shown in FIG. 2 (B). Therefore, after time t ₄ , current I flows from DC power supply 1 to load 6 through main transistor 2 and reactor 4.

The operation of the circuit of the embodiment shown in FIG. 3 is as follows. When the main transistor 2 is turned on before time t ₀ as shown in FIG. 4A, the current I through the path of the reactor 4 and the main transistor 2 as shown in FIG.
₀ flows. At this time, the first resonance capacitor 8 as shown in FIG. 4 (E) is the terminal voltage of the load 6 with the polarity shown in FIG. 3, it is charged that is, until the output voltage E _0. As shown in FIG. 4A, at time t ₀ , the main control pulse signal voltage V _B applied to the base terminal of the main transistor 2 from the control circuit 7 changes from a high level to a low level, and the main transistor 2 is turned on. 4B, the current I _TR of the main transistor 2 is immediately switched to the current flowing through the second resonance capacitor 14 as shown in FIG.
₀ is switched to the current flowing through the first resonance capacitor 8. At this time, the first resonance capacitor 8 gradually discharges, and the voltage V _C1 across the first resonance capacitor 8 drops linearly from the voltage E of the DC power supply 1 as shown in FIG. I do. Accordingly, the voltage of the second resonance capacitor 14 becomes 0V.
4D, the voltage V _C2 across the second resonance capacitor 14 rises linearly from 0 V as shown in FIG. This causes the voltage V _TR across the main transistor 2 to rise linearly from 0 V as shown in FIG. Therefore, when the main transistor 2 is turned off, zero voltage switching is performed with little overlap between the voltage waveform and the current waveform.

As shown in FIGS. 4E and 4D, at time t₁
The voltage at both ends of the first and second resonance capacitors 8 and 14 is
Pressure V_C1, V_C2Are 0V and output voltage E, respectively.₀become
And the main reflux diode 3 becomes conductive, and the first and
The current flowing through the second resonance capacitors 8 and 14 is as shown in FIG.
As shown in (F), the current I flowing through the main reflux diode 3
_DSwitch to At this time, the voltage at both ends of the main transistor 2 is
Pressure V_TRIs the output voltage E as shown in FIG.₀Equal to
No. When the main transistor 2 is off, the reactor
Current I of Torr 4₀Is the load through the main reflux diode 3.
Flow to 6.

As shown in FIG. 4A, the main control pulse signal voltage V _B applied from the control circuit 7 to the base terminal of the main transistor 2 at time t ₂ changes from a low level to a high level. Is turned on from the off state, the voltage V _TR across the main transistor 2 quickly drops to 0 V as shown in FIG. At the same time, the second resonance capacitor 14 starts discharging, and the first and second resonance capacitors 8 and 14 and the resonance reactor 10 are discharged.
Resonate, and a resonance current flows through the path of the second resonance capacitor 14, the resonance current diode 16, the resonance reactor 10, the first resonance capacitor 8, and the main transistor 2. Therefore, current I _L flowing through the resonant reactor 10 varies sinusoidally, as shown in FIG. 4 (G). At this time, the first resonance capacitor 8 is charged in a cosine waveform, and the voltage V _C1 across the first resonance capacitor 8 rises in a cosine waveform from 0 V as shown in FIG. At the same time, the voltage V across the second resonance capacitor 14 is
_{Since C2} drops in a cosine wave form from the voltage E as shown in FIG. 4D, the current I _TR of the main transistor 2 increases in a sine wave form from 0 as shown in FIG. 4B. Therefore, when the main transistor 2 is turned on, zero current switching with little overlap between the voltage waveform and the current waveform is achieved.

On the other hand, the current _ID flowing through the main reflux diode 3 is caused by the self-inducing action of the current limiting reactor 21 as shown in FIG.
As shown in (F), the current linearly decreases, and when it becomes 0 at time t ₃ , the current I _{0 of the} reactor 4 switches to the current I _TR flowing through the main transistor 2. Resonance reactor 1 at time t ₄
0 of the current I _L is equal to or 0 as shown in FIG. 4 (G), the voltage across the first and second resonance capacitor 8, 14 V
_C1, V _C2 is FIG 4 (E) and (D), respectively the output voltage as shown in E ₀ and 0V. At this time, the main transistor 2
Current I _TR of is equal to the current I ₀ of the reactor 4 as shown in FIG. 4 (B). Therefore, after time t ₄ , current I ₀ flows from DC power supply 1 through the path of reactor 4 and main transistor 2.

As described above, in the embodiment shown in FIGS. 1 and 3, zero voltage and zero current switching are achieved when the main transistor 2 is turned off and on, so that the embodiment shown in FIGS. The switching loss of the main transistor 2 can be reduced. In addition, a spike-shaped surge voltage and a surge current generated when the main transistor 2 is turned on and off are also the first.
1 and FIG. 3, the second resonance capacitors 8 and 14 are absorbed by the resonance action of the resonance reactor 10, so that the ON / OFF of the main transistor 2 is performed similarly to the embodiment shown in FIGS.
Surge voltage, surge current and noise during off operation can be reduced. Further, in the embodiment shown in FIGS.
There is an advantage that the circuit configuration can be simplified as compared with the embodiment shown in FIG.

As shown in FIGS. 5 and 6, the voltage E (in the case of the circuit of FIG. 1) of the DC power supply 1 or the output voltage E ₀ (in the case of the circuit of FIG. 1) due to the recovery recovery characteristic of the main reflux diode 3 when the main transistor 2 is turned on. In order to avoid the short-circuit state in the case of the circuit of FIG. Current limiting reactor 21
The function and effect are the same even if the device is connected in series with the main transistor 2 or in series with the DC power supply 1 (in the case of FIG. 1) or the load 6 (in the case of FIG. 3). When the recovery and recovery characteristics of the main reflux diode 3 when the main transistor 2 is turned on can be ignored in the circuits of the embodiments shown in FIGS. 1 and 3, the current limiting reactor 21 is omitted as shown in FIGS. can do.

The circuits of the embodiments shown in FIGS. 1 and 3 can be modified in the same manner as the above-described embodiments of FIGS. 1 and 3 as shown in FIGS. 7 and 8, respectively. That is, the circuits of the embodiments shown in FIG. 7 and FIG.
Between the connection point of the main reflux diode 3 and the first resonance capacitor 8 and the connection point of the first auxiliary reflux diode 11 and the main transistor 2 shown in FIG. A resonance capacitor 23 is connected in series, and a fourth auxiliary reflux is provided between a connection point of the third auxiliary reflux diode 22 and the third resonance capacitor 23 and a connection point of the main reflux diode 3 and the output capacitor 5. Connected to the diode 24. In the circuit of the embodiment shown in FIGS. 7 and 8, the current limiting reactor 21 shown in FIGS. 1 and 3 is connected in series with the main transistor 2. FIG.
Also, in the circuit shown in FIG. 8, the charging time and the discharging time of the second resonance capacitor 14 at the time of turning off and turning on the main transistor 2 are longer than those of the circuits shown in FIGS. 1 and 3. Zero voltage and zero current switching at turn-off and turn-on are shown in FIG.
3, and the switching loss can be further reduced as compared with the case of the embodiment shown in FIG.

Further, 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 main switching element has been described.
FET (MOS field effect transistor), J-FET
Other switching elements such as (junction field effect transistors) and SCRs (reverse blocking three-terminal thyristors) may be used. Further, the main switching elements are not limited to the same kind of combination.

Incidentally, the DC power supply 1 in each of the above-described embodiments is actually a single-phase or three-phase commercial AC power supply 25, 26 as shown in FIGS. In many cases, a single-phase or three-phase rectifier bridge circuit 27, 28 is used as a rectifier circuit for converting a single-phase or three-phase AC voltage of the power supplies 25, 26 into a DC voltage (of course,
A dry cell or a battery can be used as the DC power supply 1).
For example, in the circuit of the embodiment shown in FIG. 9, the DC power supply 1 of the step-up chopper type DC-DC converter A shown in FIG. 3, FIG. 6 or FIG. The reactor 4 in the step-up chopper type DC-DC converter A is connected to the AC input side of the single-phase rectification bridge circuit 27. Of course, step-up chopper type D
The DC power supply 1 may be configured by the single-phase commercial AC power supply 25 and the single-phase rectification bridge circuit 27 without changing the connection position of the reactor 4 in the C-DC converter A. In the circuit of the embodiment shown in FIG. 10, the DC power supply 1 of the step-up chopper type DC-DC converter A shown in FIG. 3, FIG. 6 or FIG. 8 is composed of a three-phase commercial AC power supply 26 and a three-phase rectification bridge circuit 28. Instead of the reactor 4 in the step-up chopper type DC-DC converter A, the reactors 4a, 4b, 4c are connected to the respective phases on the AC input side of the three-phase rectification bridge circuit 28, respectively. Of course, also in this case, the step-up chopper type DC-
The DC power supply 1 can be constituted by the three-phase commercial AC power supply 26 and the three-phase rectification bridge circuit 28 without changing the connection position of the reactor 4 in the DC converter A. In the case of the step-down chopper type DC-DC converter shown in FIG. 1, FIG. 5 or FIG. 7, the DC power supply 1 is connected to the single-phase or three-phase commercial AC power supplies 25 and 26 and the single-phase or three-phase rectification bridge circuit 27. ,
28. The rectifier circuit is a single-phase or three-phase rectifier bridge circuit 27 shown in FIGS.
The rectifier circuit is not limited to 28, and another rectifier circuit such as a single-phase or three-phase half-wave rectifier circuit, a full-wave rectifier circuit, or a voltage doubler rectifier circuit can be used as necessary.

The circuit of the embodiment shown in FIG. 11 includes a DC power supply 1 of the step-up chopper type DC-DC converter A shown in FIG. 3, FIG. 6 or FIG. Six ACs as switching elements for conversion-
It has DC conversion transistors 29-34 and six circulating current diodes 35-40 connected in parallel to each of the transistors 29-34, and each of the transistors 29-3
4 to control the three-phase commercial AC power supply 2
6 comprises a three-phase AC-DC converter circuit 41 as a rectifier circuit 4 for converting a three-phase AC voltage into a DC voltage, and replaces the reactor 4 in the step-up chopper type DC-DC converter B with a three-phase AC-DC converter. Reactors 4a, 4b, and 4c are connected to each phase on the AC input side of the circuit 41, and a power supply resonance capacitor 42 is connected between a pair of lines on the DC output side of the three-phase AC-DC converter circuit 41. . The six AC-DC conversion transistors 29 to
When a MOS-FET is used as 34, a built-in diode integrally formed with the MOS-FET can be used, so that the connection of the six circulating current diodes 35 to 40 can be omitted. In the case of a single-phase AC input, instead of the three-phase AC-DC converter circuit 41, a similar configuration having four AC-DC conversion transistors and four circulating current diodes connected in parallel to them is used. It can be easily understood that a single-phase AC-DC converter circuit may be used.

[0032]

According to the present invention, zero voltage or zero current switching of the switching element can be easily achieved, so that the overlapping portion between the voltage waveform and the current waveform of the switching element is reduced to reduce the chopper type DC-DC converter. It is possible to reduce the power loss during the ON / OFF operation of the switching element, that is, the switching loss. Further, by the resonance action of the resonance reactor and the resonance capacitor, a surge voltage, a surge current, and a noise at the time of a switching operation of a switching element used in the chopper type DC-DC converter can be reduced. In addition, since switching loss and surge voltage, surge current and noise at the time of on / off operation of the switching element can be reduced with a simple circuit configuration, the number of parts can be reduced, the manufacturing cost can be reduced, and the chopper type DC-DC converter can be reduced. Power loss can be further reduced.

[0033]

[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 shown in FIG.

FIG. 5 is an electric circuit diagram showing a first modified embodiment of the circuit shown in FIG. 1;

FIG. 6 is an electric circuit diagram showing a first modified embodiment of the circuit shown in FIG. 3;

FIG. 7 is an electric circuit diagram showing a second modified embodiment of the circuit shown in FIG. 1;

8 is an electric circuit diagram showing a second modified embodiment of the circuit shown in FIG.

FIG. 9 is an electric circuit diagram showing an embodiment in which the chopper type DC-DC converter of the present invention is connected to a single-phase rectification bridge circuit.

FIG. 10 is an electric circuit diagram showing an embodiment in which the chopper type DC-DC converter of the present invention is connected to a three-phase rectification bridge circuit.

FIG. 11 is an electric circuit diagram showing an embodiment in which the chopper type DC-DC converter of the present invention is connected to a three-phase AC-DC converter circuit.

FIG. 12 is an electric circuit diagram showing a conventional step-down chopper type DC-DC converter.

FIG. 13 is an electric circuit diagram showing a conventional step-up chopper type DC-DC converter.

FIG. 14 is a waveform chart showing an overlapping portion between the switching voltage waveform and the switching current waveform of the circuits of FIGS. 12 and 13;

[Explanation of Codes] . 1. DC power supply, . 2. a main transistor (main switching element); . 3. Main reflux diode (main reflux rectifier); . Reactor, 5. . Output capacitor, 6. . Load, 7. . Control circuit, 8, 14, 2
3. . 9. first to third resonance capacitors; . Reactors for resonance, 11, 12, 22, 24. . 35 to 40. first to fourth auxiliary reflux diodes (first to fourth auxiliary reflux rectifying elements); . 15. Diode for circulating current (rectifying element for circulating current); . 21. diode for resonance current (rectifier for resonance current); . 25. Current limiting reactor . Single-phase commercial AC power supply (AC power supply), 2
6. . 26. three-phase commercial AC power supply (AC power supply); . 28. single-phase rectifier bridge circuit (rectifier circuit); . Three-phase rectifier bridge circuit (rectifier circuit), 29-34. . 41. Transistor for AC-DC conversion (switching element for AC-DC conversion) . 42. three-phase AC-DC converter circuit (AC-DC converter circuit); . A. power supply resonance capacitor; . Step-up chopper type DC-DC converter,

Claims (9)

[Claims] (A) connecting a main switching element and a main rectifying rectifier element in series to a DC power supply and connecting a reactor between the main rectifying element and an output capacitor; or (B) A main switching element and a main circulating rectifier are connected to a DC power supply via a reactor, and an output capacitor is connected in series with the main rectifying rectifier. Connect the output capacitor and turn on the main switching element.
The chopper type DC that supplies a DC output of a voltage different from the voltage of the DC power supply to the load by performing off control.
In the DC converter, a first resonance capacitor is connected to a connection point between the main switching element and the main rectifying element, and a first auxiliary capacitor is connected to a connection point between the first resonance capacitor and the main switching element. A rectifying element for reflux is connected, and a series circuit having a reactor for resonance and a rectifying element for resonance current is connected between the first resonance capacitor and the first rectifying element for auxiliary reflux. A second auxiliary return rectifier is connected between a connection point of the resonance capacitor and the series circuit and a connection point of the main return rectifier and the output capacitor, and the first auxiliary return rectifier and A second resonance capacitor is connected between a connection point of the series circuit and a connection point of the main switching element and the DC power supply, and the main switching element is turned off. When the first resonance capacitor is discharged, the second resonance capacitor is gradually charged, and when the main switching element is turned on, the second resonance capacitor is discharged. A chopper-type DC-DC converter, wherein the first and second resonance capacitors and the resonance reactor resonate and a resonance current flows through the main switching element. 2. The chopper type DC according to claim 1, wherein the second auxiliary reflux rectifier is connected to the resonance reactor, and the second resonance capacitor is connected to the resonance current rectifier. -DC converter. 3. The chopper type DC-DC converter according to claim 1, wherein a current limiting reactor is connected in series with the main rectifying element or the main switching element. 4. A third auxiliary return circuit between a connection point between the main return rectifier element and the first resonance capacitor and a connection point between the first auxiliary return rectifier element and the main switching element. A rectifier and a third resonance capacitor are connected in series, and a connection point between the third auxiliary reflux rectifier and the third resonance capacitor and a connection point between the main reflux rectifier and the output capacitor is connected. The chopper type DC-DC converter according to any one of claims 1 to 3, wherein a fourth auxiliary reflux rectifying element is connected therebetween. 5. One main terminal of the main switching element is connected to one end of the DC power supply, and the main reflux rectifying element is connected between the other main terminal of the main switching element and the other end of the DC power supply. And the reactor is connected between the connection point of the main switching element and the main reflux rectifying element and the load, and by controlling on / off of the main switching element, the voltage of the DC power supply is reduced. The chopper type DC-DC converter according to any one of claims 1 to 4, wherein a DC output of a low voltage is supplied to the load. 6. The chopper type DC-DC converter according to claim 5, wherein the DC power supply includes an AC power supply and a rectifier circuit that converts an AC voltage of the AC power supply into a DC voltage. 7. The reactor is connected to one line of the DC power supply, one main terminal of the main switching element is connected via the reactor, and the other main terminal of the main switching element is connected to the DC power supply. And the main rectifying element is connected between one main terminal of the main switching element and the load, and the main switching element is turned on and off to thereby control the DC power supply. The chopper type DC-DC converter according to any one of claims 1 to 4, wherein a DC output of a voltage higher than a voltage of the DC power supply is supplied to the load. 8. The DC power supply includes an AC power supply, and a rectifier circuit that converts an AC voltage of the 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. The chopper type D according to claim 7,
C-DC converter. 9. A circulating power source comprising: an AC power supply; a switching element for AC-DC conversion; and a rectifying element integrally formed with the switching element for AC-DC conversion or a rectifying element connected in parallel independently. Having a current rectifying element and turning on the AC-DC converting switching element;
An AC-DC converter circuit for converting an AC voltage of the AC power supply into a DC voltage by performing off-control, wherein the reactor is connected to an AC input side of the AC-DC converter circuit, and the AC-DC converter circuit 8. A chopper type DC-DC according to claim 7, wherein a power supply resonance capacitor is connected between a pair of lines on the DC output side of the power supply.
converter.