JP2003348834A - Single-phase step-up/down converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To downsize a filter and a filter capacitor and reduce the switching loss and further to insulate the AC input power source and the DC power source of the output from each other. <P>SOLUTION: This single-phase step-up/down converter possesses a series circuit 9 which is composed of a reactor 92 connected in parallel with a series connection circuit 4 and a switching element 91, a series connection circuit which is composed of a filter capacitor 5 connected in parallel with the reactor 92 and a diode 10, and a control circuit 11 which controls the on/off of the switching circuit 91. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a single-phase buck-boost converter for obtaining a variable-voltage DC power supply from a single-phase AC power supply.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional single-phase buck-boost converter, and the prior art will be described with reference to FIG. The power obtained from the AC input power supply 1 is connected to the rectifier circuit 3 via the filter 2 and is converted to DC. The series connection circuit 4 including the reactor 42 and the switching element 41 is connected in parallel to the rectifier circuit 3, and the switching element 41 performs switching according to a signal from the control circuit 7. The series circuit of the smoothing capacitor 5 and the diode 8
2, a DC output is obtained between the terminals of the smoothing capacitor 5, and DC power is supplied to the load 20.

FIG. 7 shows the current waveform of each part. When the switching element 41 is turned on, the reactor 42
The current IL1 rises via the switching element 41 by the output voltage of the rectifier circuit 3, and when the switching element 41 is turned off, the current IL1 decreases to zero in order to charge the smoothing capacitor 5 via the diode 8. That is, when the power is on, the power is stored in the reactor, and when the power is off, the power is transferred to the smoothing capacitor 5. Therefore, the output current Is of the rectifier circuit 3 becomes a dashed line in FIG. 7, and the charging current Ic of the smoothing capacitor 5 becomes a dashed line in FIG.

[0004]

As described above, the output current Is of the rectifier circuit 3 is represented by a dashed line in FIG. 7, and the charging current Ic of the smoothing capacitor 5 is represented by a dashed line in FIG. The result is a long, discontinuous waveform. Therefore, it is necessary to increase the capacity of the filter 2 for smoothing the discontinuous current Is. When the size of the filter 2 is increased, the loss of the filter 2 also increases. Similarly, it is necessary to increase the capacity of the smoothing capacitor 5 for suppressing the ripple of the output DC voltage generated by the charging by the discontinuous Ic. That is, in the conventional configuration, the filter 2 and the smoothing capacitor 5 cannot be reduced in size, and it is difficult to reduce the size of the device and reduce the loss. The above problem can be solved by reducing the inductance value of the reactor 42 and shortening the ON / OFF cycle of the switching element 41, but the switching loss of the switching element 41 increases and the iron loss of the reactor 42 increases. . The present invention has been made in view of the above points, and aims to solve the above-described problems,
It is an object of the present invention to provide a single-phase buck-boost converter capable of reducing the size of a filter and a smoothing capacitor, reducing switching loss, and isolating an AC input power supply from an output DC power supply.

[0005]

[Means for Solving the Problems] That is, means for achieving the object are as follows: 2. The rectifier circuit 3 according to claim 1, which rectifies AC power from the AC input power supply 1, a filter 2 inserted between the AC side of the rectifier circuit 3 and the AC input power supply 1, and a DC side of the rectifier circuit 3. A series-connected switching circuit 4 of a reactor 42 and a switching element 41 connected to the power supply, a series connection of a smoothing capacitor 5 and a diode 8 connected in parallel to the reactor 42, and on / off control of the switching element 41 A control circuit 7, a reactor 92 and a switching element 91 connected between a connection point between the negative side of the rectifying circuit 3 and the switching element 41 and the positive side of the rectifying circuit 3, which are connected in parallel with the series-connected switching circuit 4. , A series connection point of the smoothing capacitor 5 and the diode 8, And a diode 10 connected between the series connection point between the quenching device 91, a single-phase buck-boost converter, characterized in that it comprises a control circuit 11 for controlling on and off of the switching element 91.

[0006] 2. 3. A rectifier circuit 3 for rectifying AC power from an AC input power supply 1, and a filter 2 inserted between the AC side of the rectifier circuit 3 and the AC input power supply 1.
A reactor 42 connected in parallel to the DC side of the rectifier circuit 3, a switching circuit 49 connected between the rectifier circuit 3 and the reactor 42,
A control circuit 7 for controlling on / off of the reactor;
2 and a smoothing capacitor 5 and a diode 8 connected in parallel.
And a switching circuit 99 and a reactor connected in parallel with the DC side of the rectifier circuit 3 and between a connection point between the negative side of the rectifier circuit 3 and the switching circuit 49 and the positive side of the rectifier circuit 3. 92 connected in series;
The switching circuit 49 includes a diode 10 connected between a connection point between the smoothing capacitor 5 and the diode 8, a connection point between the switching circuit 99 and the reactor 92, and a control circuit 11 for controlling on / off of the switching circuit 99. , Switching element 47 and diode 44
And a series connection of a diode 48 and a switching element 46 are connected in parallel, and a capacitor 45 is connected between the connection point of the switching element 47 and the diode 44 and the connection point of the diode 48 and the switching element 46. The switching circuit 99 connects the switching element 97 and the diode 94 in series and the diode 98 and the switching element 96 in series and connects the connection point of the switching element 97 and the diode 94 to the diode. A single-phase buck-boost converter characterized in that a capacitor 95 is connected between a connection point of a switching element 98 and a switching element 96.

[0007] 3. 4. A rectifier circuit 3 for rectifying AC power from an AC input power supply 1, and a filter 2 inserted between the AC side of the rectifier circuit 3 and the AC input power supply 1.
And a reactor 4 connected to the DC side of the rectifier circuit 3.
2 and a switching element 41 connected in series, and a smoothing capacitor 5 connected in parallel with the reactor 42.
And a control circuit 7 for controlling ON / OFF of the switching element 41; a reactor 92 and a switching element 91 connected in parallel with the series connection of the reactor 42 and the switching element 41; , A series connection point of the smoothing capacitor 5 and the diode 8 and the reactor 92.
A diode 10 connected between a series connection point of the switching element 91 and a control circuit 11 for controlling on / off of the switching element 91; and a switching circuit connected between the negative electrode of the rectifier circuit 3 and the switching element 41. 6 and a control circuit 12 for controlling the on / off of the switching circuit 6. The switching circuit 6 includes a series connection of a switching element 67 and a diode 64 and a series connection of a diode 68 and a switching element 66. Connecting in parallel and switching element 6
A single-phase buck-boost converter characterized in that a capacitor 65 is connected between a connection point between a diode 7 and a diode 64 and a connection point between a diode 68 and a switching element 66.

[0008] 4. 5. A rectifier circuit 3 for rectifying AC power from an AC input power supply 1, and a filter 2 inserted between the AC side of the rectifier circuit 3 and the AC input power supply 1.
And a series connection of a primary winding of a flyback transformer 43 connected to the DC side of the rectifier circuit 3 and the switching element 41, and a smoothing connected in parallel with a secondary winding of the flyback transformer 43. A series connection of a capacitor 5 and a diode 8;
1, a control circuit 7 for controlling the on / off operation of the switching element 91 and a primary winding of the flyback transformer 93 connected in series with a primary winding of the flyback transformer 43 and the switching element 41. A series connection, a diode 10 connected between a series connection point of the smoothing capacitor 5 and the diode 8 and a secondary winding of the flyback transformer 93, and control for controlling on / off of the switching element 91. Each of the flyback transformers 43 and 93 is a single-phase buck-boost converter having at least one secondary winding. Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings based on the claims.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the invention according to claim 1, and a description will be given with reference to FIG. AC input power 1
Is input to the rectifier circuit 3 via the filter 2 and is converted to DC. A series-connected switching circuit 4 including a reactor 42 and a switching element 41 and a series-connected switching circuit 9 including a reactor 92 and a switching element 91 are connected in parallel to the rectifier circuit 3, and the switching elements 41 and 91 are respectively controlled. Switching is performed according to signals from the circuit 7 and the control circuit 11. The diodes 8 and 10 supply the power stored in the reactor 42 and the reactor 92 to the smoothing capacitor 5, a DC output is obtained between the terminals of the smoothing capacitor 5, and the DC power is supplied to the load 20.

The current waveform of each part is shown in FIG. 5, and the state of the switching element 41 and the state of the switching element 91 have a phase difference of 180 degrees. Reactor 42
Current IL1 and current IL2 of reactor 92 rise by the output voltage of rectifier circuit 3 when switching element 41 and switching element 91 are on, respectively.
When the switching element 41 or the switching element 91 is off, the current IL1 or IL2 is charged to charge the smoothing capacitor 5 via the diode 8 or the diode 10.
Decreases to zero. Therefore, the output current Is of the rectifier circuit 3 becomes a dashed line in FIG. 5, and the charging current Ic of the smoothing capacitor 5 becomes a dashed line in FIG.

FIG. 5 is a waveform in the same output power state as that of FIG. 7 which is a current waveform of the prior art. The maximum value of Is is 1/2 of the conventional value and the frequency of Is is twice. Therefore, the capacity of the filter 2 for smoothing the current waveform can be reduced, and the size of the filter 2 can be reduced. Similarly, the maximum value of the charging current Ic of the smoothing capacitor is also close to 1/2, and the ripple has twice the frequency, so that the capacity of the smoothing capacitor 5 can be reduced. Although the number of switching elements, diodes, and reactors is doubled as compared with the prior art, their current capacities are reduced to about 1/2, so that there is no significant disadvantage.

An embodiment of the invention according to claim 2 is shown in FIG. 2 and will be described below with reference to FIG. The description of the same components as those in FIG. 1 will be omitted. FIG. 2 uses a switching circuit 49 including a switching element 47, a switching element 46, a diode 44, a diode 48, and a capacitor 45 instead of the switching element 41 of FIG.
, A switching circuit 9 composed of a switching element 97, a switching element 96, a diode 94, a diode 98, and a capacitor 95.
9 is used. The switching element 47 and the switching element 46 are switched by the same control signal output from the control circuit 7, and the switching element 97 and the switching element 9 are switched.
6 is switched by the same control signal output from the control circuit 11.

When the output of the control circuit 7 is off, the capacitor 4
5 is charged with the polarity shown in FIG. 2, and when the output of the control circuit 7 is turned on, the rectifier circuit 3 is short-circuited by a series circuit of the reactor 42, the switching element 47, the capacitor 45, and the switching element 46. When the switching element 47 or the switching element 46 is turned on, almost zero current is maintained, so that zero current switching is performed, and the switching loss becomes very small. Thereafter, when the voltage at both ends of the capacitor 45 becomes zero, a forward potential is applied to the diode 44 and the diode 48, so that a series circuit of the switching element 47 and the diode 44 or the switching element 46 and the diode The current of the reactor 42 flows in a series circuit with the reactor 48. Therefore, the current capacity of the switching element 47 or the switching element 46 is one of the switching elements 41 of FIG.
/ 2.

When the output of the control circuit 7 changes from on to off, the current of the reactor 42 flows through the diode 44, the capacitor 45 and the diode 48, and
5, the potential at both ends of the switching element 47 or the switching element 46 rises only gradually, so that the switching is performed at zero voltage, and the switching loss becomes very small. Thereafter, when the potential at both ends of the capacitor 45 becomes equal to or higher than the sum of the potential of the rectifier circuit 3 and the potential of the smoothing capacitor 5, the current of the reactor 42 flows through the diode 8 so as to charge the smoothing capacitor 5. The switching circuit 99 operates similarly.

As described above, since the current waveforms of the respective parts are substantially the same as in FIG. 1 and are as shown in FIG. 5, the filter 3 and the smoothing capacitor 5 can be downsized as in FIG. Further, the switching circuit 49 and the switching circuit 99 perform zero-current switching at the time of turn-on switching, and perform zero-voltage switching at the time of turn-off switching, so that switching loss can be extremely reduced.

An embodiment of the invention according to claim 3 is shown in FIG. 3 and will be described below with reference to FIG. 1 and 2
The description of the same components as described above is omitted. FIG. 3 shows a configuration in which the switching circuit 6 is inserted between the connection point between the switching element 41 and the switching element 91 in FIG. 1 and the rectifier circuit 3.
2 is controlled. The switching circuit 6 includes a switching element 67, a switching element 66, a diode 64, a diode 68, and a capacitor 65.

The output signal of the control circuit 12 is a signal corresponding to the logical sum of the output of the control circuit 7 of FIG. 1 and the output of the control circuit 11, and the output signal of the control circuit 7 of FIG. , The frequency of which is 1/2 of the frequency of the output signal of the control circuit 12, and the on / off switching point is immediately before the output signal of the control circuit 12 is turned on. The output signal of the control circuit 11 in FIG. 3 is an on / off signal obtained by inverting the logic of the output signal of the control circuit 7 in FIG. As described above, since the switching elements 41 and 91 can select the reactors 42 and 92 and the switching circuit 6 can switch the current of each reactor, the current waveform of each part is the same as that in FIGS. Becomes Therefore, as in the case of FIG. 2, although the switching loss can be extremely reduced, two diodes and one capacitor can be reduced as compared with FIG. The operation of the switching circuit 6 in FIG. 3 is the same as that of the switching circuit 49 or the switching circuit 99 in FIG. As described above, the switching of the switching elements 41 and 91 in FIG. 3 is performed immediately before the switching circuit 6 is turned on, so that the switching is performed in a state where the current is zero, and the switching loss does not increase.

An embodiment of the invention according to claim 4 is shown in FIG. 4 and will be described below with reference to FIG. The description of the same components as those in FIG. 1 is omitted. FIG. 4 shows the reactor 4 of FIG.
2 and the reactor 92 are replaced by flyback transformers 43 and 93, respectively, so that the AC input power supply 1 and the output DC power supply can be insulated. The operation of each unit is exactly the same as that in FIG.

[0019]

As described above, according to the present invention, according to the first aspect of the present invention, the ripple frequency of the output current of the filter and the charging current of the smoothing capacitor can be doubled without changing the switching frequency, and the ripple can be reduced. The amplitude is 1 /
2, the size of the filter and the smoothing capacitor can be reduced. According to Claims 2 and 3, Claim 1
It is possible to reduce the switching loss while maintaining the effect of (1). According to the fourth aspect, the AC input power supply and the output DC power supply can be insulated while maintaining the effects of the first to third aspects.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the invention according to claim 1;

FIG. 2 is a circuit diagram showing an embodiment of the invention according to claim 2;

FIG. 3 is a circuit diagram showing an embodiment of the invention according to claim 3;

FIG. 4 is a circuit diagram showing an embodiment of the invention according to claim 4;

FIG. 5 is a current waveform of each part in FIGS.

FIG. 6 is a circuit diagram illustrating an example of a conventional technique.

FIG. 7 is a current waveform of each part according to the related art.

[Explanation of symbols]

1 ... AC input power supply 2 ... Filter 3. Rectifier circuit 4: Switching circuit connected in series 5 ... Smoothing capacitor 6 Switching circuit 7 ... Control circuit 8 ... Diode 9 ... Switching circuit connected in series 10 ... Diode 11 ... Control circuit 12 ... Control circuit 20 ... Load 41 ・ ・ ・ Switching element 42 ... reactor 43 ・ ・ ・ Flyback transformer 44 ・ ・ ・ Diode 45 ・ ・ ・ Capacitor 46 Switching element 47 ・ ・ ・ Switching element 48 ・ ・ ・ Diode 49 Switching circuit 64 ... diode 65 ・ ・ ・ Capacitor 66 Switching element 67 ・ ・ ・ Switching element 68 ... diode 91 ・ ・ ・ Switching element 92 ... reactor 93 ・ ・ ・ Flyback transformer 94 ... diode 95 ... condenser 96 ・ ・ ・ Switching element 97 ・ ・ ・ Switching element 98 ・ ・ ・ Diode 99 Switching circuit

Claims (4)

[Claims] A rectifier circuit (3) for rectifying AC power from an AC input power supply (1), and a filter (2) inserted between the AC side of the rectifier circuit (3) and the AC input power supply (1). )
A serially connected switching circuit (4) of a reactor (42) and a switching element (41) connected to the DC side of the rectifier circuit (3); and a smoothing capacitor (4) connected in parallel with the reactor (42). 5) a series connection of a diode (8), a control circuit (7) for controlling on / off of the switching element (41), and the rectifier circuit connected in parallel with the series connection switching circuit (4). The negative electrode side of (3) and the switching element (4)
A switching circuit (9) in which a reactor (92) and a switching element (91) are connected in series between a connection point with the rectifier circuit (3) and a connection point with the rectifier circuit (3); the smoothing capacitor (5) and a diode (8) And a diode (10) connected between a series connection point of the reactor (92) and the switching element (91), and a control circuit (1) for controlling on / off of the switching element (91).
A single-phase buck-boost converter comprising: 2. A rectifier circuit (3) for rectifying AC power from an AC input power supply (1), and a filter (2) inserted between the AC side of the rectifier circuit (3) and the AC input power supply (1). )
A reactor (42) connected in parallel to the DC side of the rectifier circuit (3), a switching circuit (49) connected between the rectifier circuit (3) and the reactor (42),
A control circuit (7) for controlling on / off of the switching circuit (49); a series connection of a smoothing capacitor (5) and a diode (8) connected in parallel with the reactor (42); The switching circuit (99) and the reactor (3) are connected in parallel between the DC side of (3) and a connection point between the negative side of the rectifier circuit (3) and the switching circuit (49) and the positive side of the rectifier circuit (3). 92), a diode (10) connected between a connection point of the smoothing capacitor (5) and the diode (8), and a connection point of the switching circuit (99) and the reactor (92); The switching circuit (49) includes a control circuit (11) for controlling ON / OFF of a switching circuit (99). The switching circuit (49) is connected in series with a switching element (47) and a diode (44). And a series connection of a diode (48) and a switching element (46) are connected in parallel, and a connection point between the switching element (47) and the diode (44), a diode (48) and a switching element (46) are connected. A switching circuit (99) is connected in series with a switching element (97) and a diode (94), and a series connection of a diode (98) and a switching element (96). And a capacitor (95) connected between a connection point between the switching element (97) and the diode (94) and a connection point between the diode (98) and the switching element (96). Single-phase buck-boost converter. 3. A rectifier circuit (3) for rectifying AC power from an AC input power supply (1), and a filter (2) inserted between the AC side of the rectifier circuit (3) and the AC input power supply (1). )
A serially connected reactor (42) and a switching element (41) connected to the DC side of the rectifier circuit (3), and a smoothing capacitor (5) connected in parallel with the reactor (42). A series connection of a diode (8), a control circuit (7) for controlling on / off of the switching element (41), and the reactor (42)
And a switching element (41) connected in series, a reactor (92) connected in parallel with the switching element (91), and a series connection of the smoothing capacitor (5) and the diode (8). A diode (10) connected between a point, a series connection point of the reactor (92) and the switching element (91), and a control circuit (1) for controlling on / off of the switching element (91).
1) a switching circuit (6) connected between the negative electrode of the rectifier circuit (3) and the switching element (41);
A switching circuit (6) comprising a control circuit (12) for controlling on / off of the switching circuit (6);
Is connected in parallel with a series connection of a switching element (67) and a diode (64) and a series connection of a diode (68) and a switching element (66), and also includes a switching element (67) and a diode (64). , A diode (68) and a switching element (6).
6) A single-phase buck-boost converter, wherein a capacitor (65) is connected between the connection points with (6). 4. A rectifier circuit (3) for rectifying AC power from an AC input power supply (1), and a filter (2) inserted between the AC side of the rectifier circuit (3) and the AC input power supply (1). )
A serial connection of a primary winding of a flyback transformer (43) connected to the DC side of the rectifier circuit (3) and a switching element (41); and a secondary winding of the flyback transformer (43). A series connection of a smoothing capacitor (5) and a diode (8) connected in parallel with a line, a control circuit (7) for controlling on / off of the switching element (41), and a flyback transformer (4).
3) a series connection of a primary winding and a switching element (91) of a flyback transformer (93) connected in parallel with a primary winding and a switching element (41) connected in series; A diode (1) connected between a series connection point of a capacitor (5) and a diode (8) and a secondary winding of the flyback transformer (93).
0) and a control circuit (11) for controlling the on / off of the switching element (91). Each of the flyback transformers (43) and (93) has at least one secondary winding. A single-phase buck-boost converter characterized by the above-mentioned.