JP2001218452A - Voltage booster dc-dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a terminal voltage applied to a switching element of a voltage booster DC-DC converter and also reduce energy loss. SOLUTION: A voltage booster DC-DC converter is provided with an input coil (5) connected in one end to a positive input terminal (1), a switching element (6) connected between the other end of the input coil (5) and a negative input terminal (2), a positive output terminal (3) connected to the other end of the input coil (5) via a rectifying diode (7) and a clamp diode (9) connected between the other end of the input coil (5) and the positive output terminal (3). A series circuit (10) of regeneration coil (12) and a first regenerative diode (3) is connected between the clamp diode (9) and the positive side output terminal (3), the other end of the clamp capacitor (14) connected in one end between the clamp diode (9) and serial circuit (10) is connected to the negative input terminal (2) and the input coil (5) and regenerative coil (12) are magnetically connected. A DC input voltage can be boosted without providing an energy consuming means such as a snubber resistor or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC-DC converter, and more particularly to a non-insulated step-up DC-DC converter for converting a DC input voltage into a DC output voltage of a different level at a large ratio with respect to an input voltage.

[0002]

2. Description of the Related Art A step-up DC-DC converter that generates a DC output voltage higher than a DC input voltage is used for a boosting circuit from a battery. FIG. 17 shows a conventional boost type D
1 shows a circuit configuration of a C-DC converter. This step-up DC
The DC converter has a positive input terminal (1) to which DC power is supplied and a negative input terminal (2), and has an input smoothing terminal between the positive input terminal (1) and the negative input terminal (2). The capacitor (18) is connected. A switching element (6) is connected between the other end of the input side winding (5) having one end connected to the positive side input terminal (1) and the negative side input terminal (2), and the input side winding ( An output winding (15) and a rectifying diode (7) are connected in series between the other end of 5) and the positive output terminal (3). The input winding (5) and the output winding (15) are electromagnetically coupled to an autotransformer (autotransformer)
Is configured. Output smoothing capacitor between the negative output terminal (4) and the positive output terminal (3) connected to the negative input terminal (2)
(8) is connected, output side winding (15) and rectifier diode (7)
Clamp diode (9) is in parallel with the input winding (5)
And the positive side output terminal (3). The switching element (6) is configured by a semiconductor switching element having a control terminal to which a control pulse signal is applied from a control circuit (not shown). Input winding (5) and output winding (1
Since the actual autotransformer constituted by 5) has a leakage inductance (16) and an excitation inductance (17) as shown in FIG. 18, each parameter of the leakage inductance (16) and the excitation inductance (17) is set to L _s And L _p , L _p ≫L _s . Input winding (5) and output winding (1
The turns ratio of 5) is N ₁ : N _2, and the auto transformer shown in FIG. 17 is an ideal transformer (Ti).

FIG. 19 is a diagram showing a main operation of the circuit shown in FIG.
FIG. 20 shows waveforms and operation modes, and FIG.
FIG. 4 is an operation mode transition diagram illustrating an energization path. In FIG.
V₆, I₆Are the terminal voltages of the switching element (6), respectively.
Pressure, current, I₉Is the current flowing through the clamp diode (9),
I₁₆Is the current flowing through the leakage inductance (16), I₇Is in order
This is the current flowing through the diversion diode (7). Positive input terminal
DC voltage V to (1) and negative input terminal (2)_INIs applied
And the switching element (6) is turned on and off
FIG. 17, FIG. 19 and FIG.
Will be described for each operation period. Switching element (6)
Is the on-duty D_ON(0 <D_ON<1) and short enough
Switching is controlled with a short switching cycle
Of the positive output terminal (3) and the negative output terminal (4) in the switching cycle
It is assumed that the voltage between them is constant. When switching element (6) is off
T between_OFFAnd the off time T_OFFAnd ON time T_ONThe sum of
If the interval is T, the on-duty D_ONIs D_ON= T_ONAt / T
expressed. <On period (1) of switching element (6)> Switching element
In the on-period (1) when the child (6) conducts, the leakage inductance
(16) and exciting inductance (17)
_INIs applied, the leakage inductance (16) and the excitation inductance
The current value I passing through the contact (17)₁₇Rises. <When the switching element (6) turns off (2 ')>
When the switching element (6) is turned off, the leakage inductor
(16) current I_{1 6}Through the clamp diode (9)
Flows to the output terminal (3). At this time, the switching element
(6) has a DC output voltage V_OUTIs applied. Also leak in
In a series circuit of the inductance (16) and the excitation inductance (17)
(V_IN-V_OUT), The input side winding
Negative voltage is applied to (5) and excited by negative voltage of input winding (5)
And a negative voltage is also generated at the output winding (15).
Since the rectifier diode (7) turns on, the output side winding (1
The terminal voltage of 5) becomes zero without becoming negative. <Turn-off period (2) of switching element (6)> Output side winding
When the terminal voltage of the wire (15) becomes zero, the terminal of the input winding (5)
The voltage also goes to zero. The excitation connected in parallel with the input winding (5)
Since the terminal voltage of the magnetic inductance (17) also becomes zero,
During the turn-off period of the switching element (6), the excitation inductor
(17) current I₁₇Does not decay. Negative terminal voltage (V_IN-V
_OUT) Is applied to the leakage inductance (16),
Current I of inductance (16)₁₆Is ((V_IN-V_OUT) / L_s)
And the current in the input winding (5) decreases.
As a result, the current of the output winding (15) increases. Output side winding (15)
And the current flowing through the input winding (5) is the excitation inductance
When the current exceeds (17), the clamp diode (9)
Reverse recovery and shift to the off period (3) of the switching element (6).
You. <Off period (3) of switching element (6)> Switching element
When the child (6) turns off, the excitation inductance (17)
The stored energy is transferred to the DC input terminal (1)
(16), ideal transformer (Ti), rectifier diode
It is supplied to the DC output terminal (3) via (7). L_p≫L_sso
The terminal voltage of the leakage inductance (16) is almost
No. The potential of the anode terminal of the switching element (6) is
The switching element is determined by the partial pressure based on the number of turns
The terminal voltage V_S: V_S= V_IN+ {N₁× (V_OUT-V_IN)} / (N₁+ N_Two) Is applied. Current I flowing through exciting inductance (17)
₁₇Flow according to the number of turns of the transformer,
Current I flowing through the conductance (16)₁₆Is I₁₆= N₁× I₁₇/ (N₁+ N_Two). <Turn-on period (4) of switching element (6)> Switch
When the switching element (6) is turned on, the output of the auto transformer
Output voltage (-V_OUT) Is applied. this
(-N) on the input side winding (5).₁× V_OUT/ N _Two) Terminal voltage
Is excited and the terminal voltage (V_IN+ N₁× V_OUT/ N_Two) Leakage Induct
Voltage (16). The leakage inductance (16)
Style I₁₆Is the gradient I₁₆= (V_IN+ N₁× V_OUT/ N_Two) / L_s  To rise. Current I of leakage inductance (16)₁₆Is excited
Current I of inductance (17)₁₇Larger than
Reverse current flows through the diverting diode (7), and the rectifying diode
Since (7) reversely recovers, the ON period of the switching element (6)
Return to (1). Turn-off transition (2 ') and turn-on period
If the transient period of (4) is ignored, the output voltage V_OUTIs in equation (1)
expressed. V_OUT= V_IN× (1 + D_ON× N_Two/ N₁) / (1-D_ON) ・ ・ ・ (1)

As shown in FIG. 21, a positive input terminal is provided.
A series circuit of the output winding (15) and the rectifying diode (7) may be arranged between (1) and the positive output terminal (3) to separately modify the circuit of FIG. The operation of each part in each mode of the circuit shown in FIG. 21 is almost the same as in FIGS. In this specification, the same portions are denoted by the same reference numerals, and description thereof will be omitted. The output voltage V _{OUT in} FIG. 21 is expressed by equation (2). V _OUT = V _IN × {1 + D _ON × (N ₂ -1) / N ₁ } / (1-D _ON ) (2)

FIG. 22 shows a configuration in which a series circuit of a snubber resistor (22) and a snubber capacitor (19) is connected in parallel with the switching element (6), and a snubber diode is connected in parallel with the snubber resistor (22).
(23) is connected, and a terminal voltage applied to the switching element (6) is reduced by a snubber resistor (22), a snubber capacitor (19) and a snubber diode (23). Other elements are the same as those in FIG. As in FIG.
The autotransformer constituted by (5) and the output side winding (15) includes a leakage inductance (16) and an exciting inductance (17) not shown.

The operation of the circuit shown in FIG. 22 is the same as that of the circuit shown in FIG. 17, except that during the off period (3) of the switching element (6), the energy of the leakage inductance (16) is transferred to the snubber capacitor (19). ). Switch terminal voltage of switching element (6) with snubber capacitor (19)
The maximum value of the terminal voltage applied to the switching element (6) can be reduced by selecting the snubber capacitor (19) having a large capacitance. The energy stored in the snubber capacitor (19) is consumed by the current flowing through the snubber resistor (22) when the switching element (6) is turned on.

[0007]

By the way, a commonly used step-up converter requires an on-duty of 0.9 or more in order to obtain a step-up ratio of 10 times. If the turns ratio is optimized even with an on-duty close to the above, the boost ratio can be easily increased. Further, when the on-duty is brought close to 0.5, there is a great effect in stabilizing the output voltage.

However, in the configurations shown in FIGS. 17 and 21, the terminal voltage applied to the switching element (6) is high and a switching element with a high withstand voltage is required. However, the switching element with a high withstand voltage is not only expensive but also has a high conduction loss. , The converter losses increase. Further, in the circuit configuration of FIG. 22, the terminal voltage applied to the switching element (6) can be set low, but the power consumption by the snubber resistor (22) is large, and high efficiency cannot be achieved.

Accordingly, an object of the present invention is to provide a step-up DC-DC converter capable of reducing energy loss and reducing a terminal voltage applied to a switching element.

[0010]

SUMMARY OF THE INVENTION A boost DC according to the present invention
-DC converter, a positive input terminal (1) and a negative input terminal (2) to which DC power is supplied, an input winding (5) having one end connected to the positive input terminal (1), Switching element connected between the other end of the input winding (5) and the negative input terminal (2)
(6), an output winding (15) magnetically coupled to the input winding (5) and connected to one end or the other end of the input winding (5),
A positive output terminal (3) connected to the output winding (15) via a rectifying diode (7), a negative output terminal (4) connected to the negative input terminal (2), and a positive output terminal. Output terminal (3) and negative output terminal
(4) and an output smoothing capacitor (8). Connect a series circuit (11) of a clamp diode (9) and a clamp capacitor (14) in parallel with the switching element (6), and connect the clamp diode (9) and the clamp capacitor.
The regenerative winding between the connection point with (14) and the positive output terminal (3)
A series circuit (10) of (12) and a first regenerative diode (13) is connected, and the input side winding (5) and the regenerative winding (12) are magnetically coupled. Thus, the DC input voltage can be boosted without providing an energy consuming means such as a snubber resistor.
Further, since the maximum terminal voltage of the switching element (6) can be limited and suppressed by the charging voltage of the clamp capacitor (14), a switching element having a low withstand voltage can be used. Further, the energy stored in the clamp capacitor (14) is returned to the load by returning the regenerative winding (12) when the switching element (6) is turned on or off, so that the energy loss can be reduced.

In the above-mentioned step-up DC-DC converter, a regeneration switching element (20) is connected in series with a first regeneration diode (13, 13a), and an intermediate terminal of a regeneration winding (12) is connected. When connected to the positive output terminal (3) via the second regeneration diode (13b), the switching element (2
0) to turn on or off
Since the regenerative voltage (discharge voltage) of the clamp capacitor (14) can be adjusted by selecting the number of turns of (12), the switching element
There is an advantage that the maximum value of the terminal voltage of (6) can be adjusted.

Also, another boost type DC-DC according to the present invention
The converter has a positive input terminal (1) to which DC power is supplied.
A negative input terminal (2), an input winding (5) having one end connected to the positive input terminal (1), the other end of the input winding (5) and a negative input terminal (2). A switching element (6) connected between
An output winding (15) magnetically coupled to the input winding (5) and connected to the other end of the input winding (5) via a rectifying diode (7); Positive output terminal connected to (15)
(3) and the negative output terminal (4) connected to the negative input terminal (2)
And an output smoothing capacitor (8) connected between the positive output terminal (3) and the negative output terminal (4). A series circuit (11) consisting of a clamp diode (9) and a clamp capacitor (14) is connected in parallel with the switching element (6), and the connection point between the clamp diode (9) and the clamp capacitor (14) is connected to the positive output terminal. A series circuit (10) of a regenerative winding (12) and a first regenerative diode (13) is connected between
(5) and the regenerative winding (12) are magnetically coupled. In this case, a general-purpose general-purpose transformer in which the primary winding and the secondary winding are separated can be used as the input side winding (5) or the output side winding (15). It can be manufactured at a lower cost than using an autotransformer. In addition, since the connection order of the output side winding (15) and the rectifying diode (7) can be exchanged, there is an advantage that the degree of freedom of component arrangement increases.

Further, another step-up DC-DC converter according to the present invention comprises a positive input terminal (1) and a negative input terminal (2) to which DC power is supplied, and a positive input terminal (1). ), An input winding (5) having one end connected thereto, a switching element (6) connected between the other end of the input winding (5) and the negative input terminal (2), An output winding (15) magnetically coupled to the winding (5) and connected to the other end of the input winding (5) via a rectifying diode (7); ) Connected to the positive output terminal (3), the negative output terminal (4) connected to the negative input terminal (2), the positive output terminal (3) and the negative output terminal (4). And an output smoothing capacitor (8) connected therebetween. Clamp diode in parallel with switching element (6)
A series circuit (11) consisting of (9) and a clamp capacitor (14) is connected, and a clamp diode (9) and a clamp capacitor (1) are connected.
Connection point of 4), rectifier diode (7) and output side winding (15)
The first regenerative diode (13) is connected to the connection point of (1). In this case, the regenerative winding (1
2) can be configured, so that the input side winding (5) and the output side winding (15)
However, there is an advantage that the number of windings of the transformer can be reduced and the circuit configuration can be simplified.

In another boosting type DC-DC converter described above, a regenerative winding (12) is connected in series with a first regenerative diode (13, 13a), and a regenerative capacitor (21) is connected. Connected to one end of the rectifying diode (7)
Rectifier diode (7) through the regenerative diode (13b)
When the switching element (6) is connected to the other end, the voltage at the time of turn-off of the switching element (6) gradually increases from zero with charging of the clamp capacitor (14). This has the advantage of reducing stress on the subject.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a step-up type DC-
An embodiment of a DC converter will be described with reference to FIGS. However, in these drawings, the same portions as those shown in FIGS. 17 to 22 are denoted by the same reference numerals, and description thereof will be omitted.

A step-up DC-DC converter according to the present invention
FIG. 1 shows a first embodiment of the present invention. In the first embodiment
Is a clamp diode in parallel with the switching element (6).
Series circuit (11) of (9) and clamp capacitor (14) is connected
Is done. Clamp diode (9) and clamp capacitor
The regenerative winding between the connection point with (14) and the positive output terminal (3)
The series circuit (10) of (12) and the first regenerative diode (13)
Connected, the input side winding (5) and the regenerative winding (12) are magnetic
Is combined with Number of turns of input side winding (5) and output side winding (15)
The ratio is N₁: N_TwoAnd the number of turns of the regenerative winding (12) is M.
You. FIG. 2 shows the structure of the autotransformer (T) of FIG. 1 in detail.
It is good. The auto transformer (T) has an input winding (5) and an output
Ideal transformer including side winding (15), leakage inductance
(16) and the exciting inductance (17). FIG.
Shows the main waveforms and energizing periods during the switching operation in FIG.
Is shown. In FIG.₁₄Is a clamp capacitor (14)
Terminal voltage, I₁₃Is the current flowing through the regenerative diode (13)
Is shown. FIG. 4 shows an energization path in each operation period. Below
2 will be described with reference to FIGS. 3 and 4 for each operation period.
I do. <When switching element (6) is on (1)>
Control signal from the path to the control terminal of the switching element (6).
When the switching element (6) turns on, the leakage
Series circuit of conductance (16) and excitation inductance (17)
DC input voltage V_INIs applied and the excitation inductance (1
7) Current I₁₇Rises. <Transition time of switching element (6) (2 ')>
When the switching element (6) is turned off, the leakage inductance (1
The current flowing through 6) and the exciting inductance (17) is clamped.
The current flows to the clamp capacitor (14) through the diode (9).
At the same time, with the voltage applied to the input winding (5).
The terminal voltage of the output winding (15) is generated, and the anode potential
The rectifying diode (7), which rises, is turned on. <When switching element (6) is shut off (2)> Leakage inductance
Reverse voltage is applied to the source (16) and the leakage inductance (16)
Current I₁₆Decays. As a result, the input winding (5)
The current decreases, and the current of the output winding (15) increases. Leak
The energy of the conductance (16) is the clamp capacitor (14)
But the current flowing through the output side winding (15) and the input side
The difference in the current flowing through the winding (5) is
Current I₁₇Larger than the clamp diode (9)
Recovers reversely, and the charging current to the clamp capacitor (14) decreases.
Disappears. <Off state (3) of switching element (6)> Excitation inductor
The energy stored in the impedance (17) is transferred to the DC input terminal (1),
Leakage inductance (16), input winding (5), output winding
(15) and the positive output terminal (3) via the rectifier diode (7)
Supplied to <When the commutation of the switching element (6) is transient (4)> Switching
When the element (6) turns on, the output winding (15)
Voltage (-V_{OU T}) Is applied. Accordingly, the terminal voltage (V_IN+
N₁× V_OUT/ N_Two) Is applied to the leakage inductance (16)
And the current I of the leakage inductance (16)₁₆Is {(V_IN+ N₁
× V _OUT/ N_Two) / L_s} And rise. Leakage inductance
(16) Current I₁₆Is the current I of the exciting inductance (17)₁₇Yo
The reverse current flows through the rectifier diode (7).
As a result, the rectifying diode (7) reversely recovers. <Discharge of clamp capacitor (14) (5)> Input winding (5)
Input voltage V_INVoltage at a level approximately equal to
Voltage (M × V) for the output side winding (15)._IN/ N₁)But
Applied. As a result, the storage in the clamp capacitor (14)
The voltage due to the accumulated charge is (V_OUT-M × V_IN/ N₁)
Energy stored in the clamp capacitor (14)
Not shown via raw winding (12) and regenerative diode (13)
Is regenerated to a heavy load. In addition, the clamp capacitor (14)
Charge voltage V₁₄Terminal voltage of the switching element (6)
Pressure V₆Can be limited. Clamp con
The energy charged in the capacitor (14) passes through the output winding (15).
When the switching element (6) is turned on, a negative
Since the load is regenerated, the increase in loss due to the clamp circuit is
Absent.

A regenerative winding (12) for the embodiment of FIG.
FIG. 5 shows a second embodiment of the present invention in which the winding direction is reversed. The other components in FIG. 5 are the same as those in FIG. FIG. 6 is a circuit diagram showing the auto transformer (T) of FIG. 5 in detail. FIG. 7 shows main waveforms and energization periods during the switching operation of FIG. FIG. 8 shows an energization path in each period. Hereinafter, the circuit operation of FIG. 6 will be described for each operation period with reference to FIGS. 7 and 8. The operations when the switching element (6) is turned on (1), when the switching element (6) is turned off (2 '), and when the switching element (6) is turned off (2) are the same as those in FIGS. Therefore, the description is omitted. <Occurrence of interruption of the switching element (6) (3)> terminal voltage V _M = M × regenerative winding _{(12) (V OUT -V IN} ) / (N 1 + N 2) is excited, the clamp capacitor (14 terminal voltage V ₁₄ of) is, (V _OUT
When −V _M ) or more, the clamp capacitor (14) is discharged. <Off state (4) of switching element (6)> The energy stored in the exciting inductance (17) is the positive input terminal (1),
It is supplied to the DC output terminal (3) via the leakage inductance (16), the ideal transformer (Ti), and the rectifying diode (7). <Transition transition (5) of switching element (6)> When the switching element (6) is turned on, a positive voltage is applied to the input side winding (5), and accordingly, the regeneration winding (12) is turned on. ), The voltage is excited, so that the clamp capacitor (14) slightly discharges. By the operation, the maximum value of the terminal voltage V ₆ of the switching element (6) is limited by the clamp capacitor (14). The energy charged in the clamp capacitor (14) is supplied to the regenerative winding when the switching element (6) is turned on.
Since the load is regenerated to the load (not shown) via (12), the loss due to the clamp circuit does not increase.

FIG. 9 shows an input side winding (5) and an output side winding (15).
Is shown in a third embodiment according to the present invention in which are connected in parallel with each other. In the circuit diagram shown in FIG.
Operation waveforms such as the operation timing (6), voltage and current, and current of an exciting inductance (not shown) are the same as those of the first embodiment shown in FIG. 1, and similar to the first embodiment,
Can be the charging voltage V ₁₄ of the clamp capacitor (14) limits the maximum value of the terminal voltage V ₆ of the switching element (6).

FIG. 10 shows the present invention in which the regenerative winding (12) shown in FIG. 1 is constituted by the first regenerative winding (12a) and the second regenerative winding (12b) connected in series. 4 shows a fourth embodiment according to the present invention. The second regeneration winding (12b) is connected to the positive output terminal (3) via the regeneration switching element (20) and the first regeneration diode (13a). A connection point between the first regeneration winding (12a) and the second regeneration winding (12b) is connected to the positive output terminal (3) via the second regeneration diode (13b). The number of turns of the first regenerative winding (12a) and the second regenerative winding (12b) is M ₁ and M ₂ , and the other configuration is the same as that of FIG. In the fourth embodiment, the same operation and effect as those of the first and second embodiments are produced, and further, the on / off of the regenerative switching element (20) is switched to generate the regenerative winding.
By selecting the number of turns of (12), {V _OUT- (M ₁ + M ₂ ) × V _IN
/ N ₁ } or (V _OUT -M ₁ × V _IN / N ₁ ), the regenerative voltage (discharge voltage) of the clamp capacitor (14) can be selected, so the voltage adjustment of the clamp capacitor (14) Accordingly, you adjust the maximum value of the terminal voltage V ₆ of the switching element (6).

FIG. 11 shows the input side winding in the circuit of FIG.
A fifth embodiment according to the present invention in which a rectifying diode (7) is connected between (5) and the output side winding (15) is shown. The circuit of FIG. 11 is the same as the circuit of FIG. 5 except that the input winding (5) and the output winding (15) are connected via a rectifying diode (7). In the fifth embodiment, a general-purpose general-purpose transformer in which a primary winding and a secondary winding are separated is used as the input side winding (5) or the output side winding (15). It can be made cheaper than using an autotransformer. The output winding (15) and the rectifier diode
Since the order of connection with (7) can be changed, the degree of freedom of arrangement increases.

FIG. 12 shows a sixth embodiment according to the present invention in which the output side winding (15) acts as a regeneration winding (12). In FIG. 12, when the switching element (6) is turned off, the energy of the leakage inductance (16) is transferred to the clamp capacitor (14). The terminal voltage V ₆ of the switching element (6) is limited by the terminal voltage V ₁₄ of the clamp capacitor (14), the terminal voltage V ₆ of the switching element (6) can be prevented from becoming excessive. At this time, the terminal voltage V ₁₄ of the clamp capacitor (14) is increased, the switching element
When (6) is in the off state, the clamp capacitor (14)
The terminal voltage V ₁₄ of the is discharged to _{{V IN + N 1 × (} V OUT -V IN) / (N 1 + N 2)}. Therefore, a large capacitance clamp capacitor
If you choose (14), {V terminal voltage V ₆ of the switching element (6)
_{IN + N 1 × (V O} UT -V IN) / (N 1 + N 2) can be clamped to the level of}. The sixth embodiment has the same effect as the second embodiment, and further has a regenerating winding (1) provided by an output winding (15).
2) can be configured, so that the input side winding (5) and the output side winding (15)
However, there is an advantage that the number of windings of the transformer can be reduced and the circuit configuration can be simplified.

FIG. 13 shows a circuit shown in FIG. 12, in which the regenerative winding (12) is connected to the connection point between the clamp diode (9) and the clamp capacitor (13), and the regenerative winding (12) is connected to the output. A first regenerative diode (13a) and a second regenerative diode (13b) are connected between the side coil (15) and the first regenerative diode (13b).
Regeneration diode (13a) and the second regeneration diode (13a).
b) A seventh embodiment according to the present invention in which the other end of the regenerative capacitor (21) having one end connected thereto is connected between the input winding (5) and the output winding (15). Is shown. In FIG. 13, the capacities of the clamp capacitor (14) and the regenerative capacitor (21) are equal. In FIG. 13, since the voltage when the switching element (6) is turned off gradually rises from zero with the charging of the clamp capacitor (14), the voltage becomes zero voltage and the electric stress on the switching element (6) can be reduced. .

FIG. 14 shows the input winding (5) and the output of FIG.
Circuit diagram showing in detail the autotransformer consisting of the side winding (15)
It is. FIG. 15 is a diagram showing the main operations during the switching operation of FIG.
It is a waveform and an energization period. In FIG._13aas well as
I_13bAre the first regenerative diode (13a) and the second
5 shows the current flowing through the regenerative diode (13b). FIG.
Indicates an energization path in each operation period. FIG. 15 and FIG.
13 will be described for each operation period. <When switching element (6) is on (1)> Switching element
A control signal is applied to the control terminal of (6), and the switching element is
When the child (6) is turned on, the
Terminal voltage V of the pump capacitor (14)₁₄Is zero.
The terminal voltage of the capacitor (21) is {-V_IN+ N₁× (V_OUT-V_IN) / (N₁+ N
_Two)}. Leakage inductance (16) and exciting inductor
A voltage is applied to the inductance (17) and the excitation inductance (17) is
Current I₁₇Rises. <When switching element (6) is off (2)> Switching element
When (6) turns off, the leakage inductance (16) and
The current flowing through the exciting inductance (17) is
It flows to the clamp capacitor (14) via the load (9). K
Switch limited by charging of lamp capacitor (14)
Terminal voltage V of the switching element (6)₆Slowly rises from zero
You. <When switching element (6) is shut off (3)> Switching element
As the terminal voltage of (6) rises, the regenerative capacitor (21)
From the second regenerative diode (13b) and the output winding (15).
Current flows through it and discharges to a load (not shown)
Since a reverse voltage is applied to the leakage inductance (16),
Current I of leakage inductance (16)₁₆Decays. <When switching element (6) is shut off (4)> Leakage reactor (1
6) Current I flowing₁₆Flow through the output side winding (15)
When the currents are equal, the clamp diode (9)
Reversely recovers, and the switching element (6) is turned off. <When switching element (6) is shut off (5)> Regeneration capacitor
When the terminal voltage of (21) discharges to positive, the rectifying diode
The forward voltage is applied to (7), and it becomes conductive. Clan
Terminal capacitor V₁₄But V₁₄= {V_IN+ N₁× (V_OUT-V_IN) / (N₁+ N_Two)｝, The regenerative winding (12), the first regenerative diode
Via a second diode (13a) and a second regenerative diode (13b),
The clamp capacitor (14) is V₁₄= {V_IN+ N₁× (V_OUT-V_IN) / (N₁+ N_TwoDischarge to)｝. <When commutation of switching element (6) (6)> Switching element
With the commutation of (6), the terminal voltage V of the switching element (6)
₆Becomes zero, so that the rectifying diode (7) reversely recovers. <When commutation of switching element (6) (7)> Switching element
(6), Clamp capacitor (14), Regenerative winding (12), 1st
Through the regenerative diode (13a) and the regenerative capacitor (21).
Resonance occurs in the road. This resonance causes the clamp
The energy stored in the capacitor (14) is
Move on to (21). Therefore, the clamp capacitor (14)
Terminal voltage V₁₄Is {V_IN+ N₁× (V_OUT-V_IN) / (N₁+ N_Two)} To zero
And the terminal voltage of the regenerative capacitor (21) changes from zero to [-{V
_IN+ N₁× (V_OUT-V_IN) / (N₁+ N_Two)}]. Clamp conde
Energy transfer from the sensor (14) to the regenerative capacitor (21)
Is completed, the switching element (6) is turned on,
The operation returns to (1) when the switching element (6) is turned on. The movement
Depending on the operation, the terminal voltage V of the switching element (6)₆Is
Limited by charging lamp capacitor (14), terminal voltage
Pressure V₆Gradually rises from zero, so the soft switch
And The energy charged in the clamp capacitor (14)
The lugi is connected to a load (not shown) via the regenerative capacitor (21).
Energy loss due to the snubber circuit.
There is no addition.

[0024]

According to the present invention, the maximum value of the terminal voltage applied to the switching element can be reduced by the action of the clamp capacitor. Thus, a switching element having a low withstand voltage can be used, so that conduction loss of the switching element can be reduced. For example, FET with a withstand voltage of 100 V or less
In this case, the conduction resistance becomes several mΩ.
Since it is 0 to 100 mΩ, conduction loss is reduced. In addition, since the energy of the clamp capacitor can be regenerated to the load, the clamp circuit has no loss, and a non-insulated step-up DC-DC converter that can ensure a high efficiency and a high step-up ratio can be realized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a step-up DC-DC converter according to the present invention.

FIG. 2 is a circuit diagram showing the first embodiment in detail.

FIG. 3 is an operation waveform diagram of each section of the circuit generated in the first embodiment.

FIG. 4 is an energization path in each operation period according to the first embodiment.

FIG. 5 is a circuit diagram showing a step-up DC-DC converter according to a second embodiment of the present invention;

FIG. 6 is a circuit diagram showing a second embodiment in detail.

FIG. 7 is an operation waveform diagram of each part of a circuit generated in the second embodiment.

FIG. 8 is an energization path in each operation period according to the second embodiment.

FIG. 9 is a circuit diagram showing a step-up DC-DC converter according to a third embodiment of the present invention;

FIG. 10 is a circuit diagram showing a step-up DC-DC converter according to a fourth embodiment of the present invention;

FIG. 11 is a circuit diagram showing a fifth embodiment of a step-up DC-DC converter according to the present invention;

FIG. 12 is a circuit diagram showing a step-up DC-DC converter according to a sixth embodiment of the present invention;

FIG. 13 is a circuit diagram showing a seventh embodiment of the step-up DC-DC converter according to the present invention;

FIG. 14 is a circuit diagram showing a seventh embodiment in detail.

FIG. 15 is an operation waveform diagram of each section of the circuit generated in the seventh embodiment.

FIG. 16 shows energization paths in each operation period according to the seventh embodiment.

FIG. 17 is a circuit diagram of a conventional step-up DC-DC converter.

18 is a detailed circuit diagram of the step-up DC-DC converter of FIG.

19 is an operation waveform diagram of the circuit in FIG.

20 is an energization path in each operation period of the circuit in FIG.

FIG. 21 is another circuit diagram showing a conventional step-up DC-DC converter.

FIG. 22 is still another circuit diagram showing a conventional step-up DC-DC converter.

[Explanation of symbols]

(1) ・ ・ Positive input terminal, (2) ・ ・ Negative input terminal, (3)
..Positive output terminal, (4) Negative output terminal, (5)
Input winding, (6) Switching element, (7) Rectifier diode, (8) Output smoothing capacitor, (9)
..Clamp diode, (10), (11)
(12) Regeneration winding, (13) Regeneration diode,
(13a) ··· First regenerative diode, (13b) ··· Second
(14) Clamp capacitor,
(15) ・ ・ Output winding, (16) ・ ・ Leakage inductance, (17) ・ ・ Excitation inductance, (20) ・ ・ Regeneration switching element, (21) ・ ・ Regeneration capacitor,

Claims (5)

[Claims] 1. A positive input terminal and a negative input terminal to which DC power is supplied, an input winding having one end connected to the positive input terminal, the other end of the input winding and the negative input terminal. A switching element connected between the input-side winding and an output-side winding magnetically coupled to the input-side winding and connected to one end or the other end of the input-side winding; A positive output terminal connected to the line via a rectifying diode, a negative output terminal connected to the negative input terminal, and a positive output terminal connected between the positive output terminal and the negative output terminal. In a step-up DC-DC converter including an output smoothing capacitor, a series circuit of a clamp diode and a clamp capacitor is connected in parallel with the switching element, and a connection point between the clamp diode and the clamp capacitor and the positive output Terminal and Boost D which connects the series circuit, and wherein the bound and said regeneration winding and the input side winding magnetically with a regenerative winding first regenerative diode between
C-DC converter. 2. A regenerative switching element is connected in series with the first regenerative diode, and an intermediate terminal of the regenerative winding is connected to the positive output terminal via a second regenerative diode. The step-up DC-D according to claim 1.
C converter. 3. A positive input terminal and a negative input terminal to which DC power is supplied, an input winding having one end connected to the positive input terminal, the other end of the input winding and the negative input terminal. A switching element connected between the input-side winding and an output-side winding magnetically coupled to the input-side winding and connected to the other end of the input-side winding via a rectifying diode; A positive output terminal connected to the output winding; a negative output terminal connected to the negative input terminal; and an output smoothing terminal connected between the positive output terminal and the negative output terminal. In a step-up DC-DC converter including a capacitor, a series circuit of a clamp diode and a clamp capacitor is connected in parallel with the switching element, and a connection point between the clamp diode and the clamp capacitor, the positive output terminal, Times between A series circuit of the use winding and the first regenerative diode, Boost D, characterized in that combined with said input winding and said regeneration winding magnetically
C-DC converter. 4. A positive input terminal and a negative input terminal to which DC power is supplied, an input winding having one end connected to the positive input terminal, the other end of the input winding and the negative input terminal. A switching element connected between the input-side winding and an output-side winding magnetically coupled to the input-side winding and connected to the other end of the input-side winding via a rectifying diode; A positive output terminal connected to the output winding; a negative output terminal connected to the negative input terminal; and an output smoothing terminal connected between the positive output terminal and the negative output terminal. In the step-up DC-DC converter including a capacitor, a series circuit of a clamp diode and a clamp capacitor is connected in parallel with the switching element, and a connection point of the clamp diode and the clamp capacitor is connected to the rectifying diode and First step-up DC-DC converter, characterized in that the regenerative diode is connected between a connection point of the output side windings. 5. A regenerative winding is connected in series with the first regenerative diode, connected to one end of the rectifier diode via a regenerative capacitor, and connected via a second regenerative diode. 5. The step-up DC-DC converter according to claim 4, which is connected to the other end of the rectifying diode.