JP2009178020A - Switching power supply - Google Patents

Abstract

A switching power supply device capable of supplying a stable output while suppressing manufacturing costs is provided.
In a smoothing circuit 5, a magnetic flux formed by a magnetic flux in a first annular magnetic path B1, a magnetic flux in a second annular magnetic path B2, a magnetic flux formed by a current flowing through a choke coil 5Lc1, and a current flowing through a choke coil 5Lc2. The magnetic flux to be generated is shared with each other inside the common magnetic cores UCc and DCc. The current flowing through the choke coils 5L1 and 5L3 and the current flowing through the choke coils 5L2 and 5L4 are balanced and stabilized. Further, since the smoothing circuit 5 automatically maintains such an equilibrium state, it is not necessary to adjust the characteristic values of the elements.
[Selection] Figure 1

Description

  The present invention relates to a switching power supply device configured to extract a switching output obtained by switching a DC input voltage to an output winding of a power conversion transformer.

  Conventionally, various DC-DC converters have been proposed as switching power supply devices and put into practical use. Most of them use a switching circuit connected to the primary winding of the power conversion transformer (transformer element) to switch the DC input voltage and extract the switching output to the secondary winding of the power conversion transformer. is there. With the switching operation of the switching circuit, the voltage appearing in the secondary winding is rectified by the rectifier circuit, then converted to direct current by the smoothing circuit and output.

  By the way, in such a switching power supply device, when using a plurality of rectifier circuits for the purpose of suppressing a voltage drop in a rectifier circuit or a smoothing circuit to handle a large current, a smoothing using an LC circuit is used. It is necessary to stabilize the output by balancing currents flowing from the rectifier circuits using a circuit. Therefore, for example, Patent Document 1 proposes a technique in which magnetic fluxes generated by current flowing from each rectifier circuit are balanced by using an inductor having two magnetic cores.

US Pat. No. 6,362,986

  However, although the magnetic fluxes are balanced to some extent by the method according to Patent Document 1, for that purpose, adjustment or selection of the characteristic value of the element or the use of an element having a large margin for the characteristic value or the like is required. I had to. Accordingly, there are problems that the degree of freedom in design is reduced and the manufacturing cost is increased.

  The present invention has been made in view of such problems, and an object thereof is to provide a switching power supply device capable of supplying a stable output while suppressing manufacturing cost.

  The first switching power supply device of the present invention includes an inverter circuit that switches a DC input voltage to generate an input AC voltage, a primary winding on the inverter circuit side, and a secondary winding. A transformer that transforms the input AC voltage and outputs an output AC voltage, two rectifier circuits that are connected in parallel to the secondary side of the transformer, and each perform a rectification operation of the output AC voltage, and from these two rectifier circuits And a smoothing circuit that generates a DC output voltage by smoothing the output voltage. Here, the smoothing circuit has a capacitive element, first and second magnetic cores, a common magnetic core disposed between the first and second magnetic cores, and one end connected to the rectifier circuit. And first and second windings wound around the first magnetic core, and third and fourth windings having one end connected to the rectifier circuit and wound around the second magnetic core, The other ends of the first and third windings are connected to one end of the capacitor and the first common winding wound around the common magnetic core and the other ends of the second and fourth windings And the other end of the capacitive element and a second common winding wound around a common magnetic core. Also, a first annular magnetic path that passes through the first magnetic core and the common magnetic core is formed by the current flowing through the first winding and the current flowing through the second winding, and the first winding In synchronization with the current flowing through the second winding and the current flowing through the second winding, current flows through the third and fourth windings, and the current flowing through the third winding and the current flowing through the fourth winding To form a second annular magnetic path that passes through the inside of the second magnetic core and the common magnetic core, the magnetic flux in the first annular magnetic path, the magnetic flux in the second annular magnetic path, and the first common The magnetic flux formed by the current flowing through the winding and the magnetic flux formed by the current flowing through the second common winding are shared with each other inside the common magnetic core. Note that “synchronized” is not limited to literally completely synchronized, but means substantially synchronized.

  In the first switching power supply device of the present invention, the input AC voltage is generated by switching the DC input voltage by the inverter circuit, the input AC voltage is transformed by the transformer, and the output AC voltage is output to the secondary side. The The two rectifier circuits rectify the output AC voltage, and the output voltages from the two rectifier circuits are smoothed by the smoothing circuit, thereby generating a DC output voltage. Here, in the smoothing circuit, the first to fourth windings and the first and second common windings are appropriately wound around the first and second magnetic cores and the common magnetic core. Thus, a first annular magnetic path passing through the first magnetic core and the common magnetic core is formed by the current flowing through the first winding and the current flowing through the second winding, and the first winding In synchronization with the current flowing through the second winding and the current flowing through the second winding, current flows through the third and fourth windings, and the current flowing through the third winding and the current flowing through the fourth winding As a result, a second annular magnetic path passing through the inside of the second magnetic core and the common magnetic core is formed. Further, the magnetic flux formed in the first annular magnetic path, the magnetic flux in the second annular magnetic path, the magnetic flux formed by the current flowing through the first common winding, and the second common winding. The magnetic flux formed by the electric current becomes equal to each other and shared with each other inside the common magnetic core. As a result, the current flowing through the first and second windings and the current flowing through the third and fourth windings are balanced and stabilized. In addition, since such an equilibrium state is automatically maintained, it is not necessary to adjust the characteristic value of the element.

  In the first switching power supply device of the present invention, the two rectifier circuits are constituted by first and second rectifier circuits each having a current inflow end and a current outflow end, and one end of the first winding. Is connected to the current outflow end of the first rectifier circuit, one end of the second winding is connected to the current inflow end of the first rectifier circuit, and one end of the third winding is connected to the second rectifier circuit. The one end of the fourth winding may be connected to the current inflow end of the second rectifier circuit.

  In the first switching power supply device of the present invention, the two rectifier circuits are constituted by first and second rectifier circuits each having a current inflow end and a current outflow end, and one end of the first winding. Is connected to the current outflow end of the second rectifier circuit, one end of the second winding is connected to the current inflow end of the first rectifier circuit, and one end of the third winding is connected to the first rectifier circuit. The one end of the fourth winding may be connected to the current inflow end of the second rectifier circuit.

  In the first switching power supply device of the present invention, the transformer is constituted by a first transformer having a pair of secondary windings and a second transformer having a pair of secondary windings, and A first rectifier having two rectifier circuits having a current inflow end and a current outflow end and connected to one secondary winding of the first transformer and the other secondary winding of the second transformer And a second rectifier circuit having a current inflow end and a current outflow end and connected to the other secondary winding of the first transformer and the one secondary winding of the second transformer. And one end of the first winding is connected to the current outflow end of the first rectifier circuit, one end of the second winding is connected to the current inflow end of the first rectifier circuit, and the third One end of the fourth winding is connected to the current outflow end of the second rectifier circuit, and one end of the fourth winding is It may be connected to the current inlet of the second rectifier circuit.

  In the first switching power supply device of the present invention, it is preferable that the transformer has a pair of primary windings that are connected in series to each other and alternately increase in AC resistance during switching operation by the inverter circuit. . In such a configuration, when currents in opposite directions flow between the primary side winding and the secondary side winding of the transformer, the AC resistance is lowered due to the skin effect and the proximity effect. Therefore, since the oscillation component is absorbed by the primary winding having a relatively high AC resistance, output ringing is suppressed.

  In the first switching power supply device of the present invention, the inverter circuit is preferably constituted by a single inverter circuit. When configured in this way, the circuit configuration is simplified and the manufacturing cost is further suppressed as compared with the case where the inverter circuit is configured by a plurality of inverter circuits.

  The second switching power supply device of the present invention converts the DC input voltage input from one input / output terminal pair of the first and second input / output terminal pairs to a voltage from the other input / output terminal pair. A first transformer winding arranged on the first input / output terminal pair side; a second transformer winding arranged on the second input / output terminal pair side; A first transformer including a plurality of first switching elements, and a first rectifying element connected in parallel to each of the plurality of first switching elements. Two circuits including a circuit, a second transformer winding side, each including a plurality of second switching elements and a second rectifier element connected in parallel to the plurality of second switching elements, respectively. A second circuit and these two second It is obtained by a smoothing circuit disposed between the road and the second input terminal pair. Here, the smoothing circuit includes a capacitive element, first and second magnetic cores, a common magnetic core disposed between the first and second magnetic cores, and one end connected to the second circuit. And the first and second windings wound around the first magnetic core, and the third and fourth windings having one end connected to the second circuit and wound around the second magnetic core. A first common winding wound around the common magnetic core and connected to the other ends of the first and third windings and one end of the capacitive element; The other end of the capacitor and the other end of the capacitive element, and a second common winding wound around the common magnetic core. Also, a first annular magnetic path that passes through the first magnetic core and the common magnetic core is formed by the current flowing through the first winding and the current flowing through the second winding, and the first winding In synchronization with the current flowing through the second winding and the current flowing through the second winding, current flows through the third and fourth windings, and the current flowing through the third winding and the current flowing through the fourth winding To form a second annular magnetic path that passes through the inside of the second magnetic core and the common magnetic core, the magnetic flux in the first annular magnetic path, the magnetic flux in the second annular magnetic path, and the first common The magnetic flux formed by the current flowing through the winding and the magnetic flux formed by the current flowing through the second common winding are shared with each other inside the common magnetic core.

  In the second switching power supply device of the present invention, during forward operation, a DC input voltage is input from the first input / output terminal pair, and the input is input by the first switching element in the first circuit functioning as an inverter circuit. An alternating voltage is generated. Further, when this input AC voltage is input to the first transformer winding side of the transformer, it is transformed, and an output AC voltage is output from the second transformer winding side. The output AC voltage is rectified by the second rectifier elements in the two second circuits functioning as rectifier circuits, and the output voltages from the two second circuits are smoothed by the smoothing circuit. Thus, a DC output voltage is output from the second input / output terminal. On the other hand, during reverse operation, a DC input voltage is input from the second input / output terminal pair, and through the smoothing circuit, the second switching elements in the two second circuits, each functioning as an inverter circuit, An input AC voltage is generated. Further, when this input AC voltage is input to the second transformer winding side of the transformer, it is transformed, and an output AC voltage is output from the first transformer winding side. The output AC voltage is rectified by the first rectifying element in the first circuit functioning as a rectifying circuit, and a DC output voltage is output from the first input / output terminal. Here, in the smoothing circuit, the first to fourth windings and the first and second common windings are appropriately wound around the first and second magnetic cores and the common magnetic core. Thus, a first annular magnetic path passing through the first magnetic core and the common magnetic core is formed by the current flowing through the first winding and the current flowing through the second winding, and the first winding In synchronization with the current flowing through the second winding and the current flowing through the second winding, current flows through the third and fourth windings, and the current flowing through the third winding and the current flowing through the fourth winding As a result, a second annular magnetic path passing through the inside of the second magnetic core and the common magnetic core is formed. Further, the magnetic flux formed in the first annular magnetic path, the magnetic flux in the second annular magnetic path, the magnetic flux formed by the current flowing through the first common winding, and the second common winding. The magnetic flux formed by the electric current becomes equal to each other and shared with each other inside the common magnetic core. As a result, the current flowing through the first and second windings and the current flowing through the third and fourth windings are balanced and stabilized. In addition, since such an equilibrium state is automatically maintained, it is not necessary to adjust the characteristic value of the element.

  According to the switching power supply device of the present invention, in the smoothing circuit, the first annular magnetic path passing through the first magnetic core and the common magnetic core is formed, and the second magnetic core and the common magnetic core are passed through. A second annular magnetic path is formed, the magnetic flux formed in the first annular magnetic path, the magnetic flux in the second annular magnetic path, the magnetic flux formed by the current flowing through the first common winding, and the second common Since the magnetic flux formed by the current flowing through the windings is equal in direction and shared with each other within the common magnetic core, the currents flowing through the first and second windings and the third And the current flowing through the fourth winding can be balanced and stabilized. Further, since such an equilibrium state is automatically maintained, it is not necessary to adjust the characteristic value of the element, and a large margin is not required for the characteristic value of the element. Therefore, it is possible to supply a stable output while suppressing the manufacturing cost.

  Hereinafter, the best mode for carrying out the present invention (hereinafter simply referred to as an embodiment) will be described in detail with reference to the drawings.

  FIG. 1 shows a circuit configuration of a switching power supply device (switching power supply device 1) according to an embodiment of the present invention. The switching power supply device 1 functions as a DC-DC converter that converts a high-voltage DC input voltage Vin supplied from the high-voltage battery 10 into a lower DC output voltage Vout and supplies the low-voltage battery (not shown) to drive the load 6. To do.

  The switching power supply device 1 includes an input smoothing capacitor 2 provided between the primary high voltage line L1H and the primary low voltage line L1L, and the primary high voltage line L1H and the primary low voltage line L1L. Inverter circuits 11 and 12 provided in parallel to each other, a transformer 31 having a primary side winding 311 and secondary side windings 312A and 312B, a primary side winding 321 and secondary side windings 322A and 322B And a transformer 32 having. A DC input voltage Vin output from the high voltage battery 10 is applied between the input terminal T1 of the primary high voltage line L1H and the input terminal T2 of the primary low voltage line L1L. The switching power supply device 1 also includes two rectifier circuits, that is, a rectifier circuit 41 provided on the secondary side of the transformer 31 and a rectifier circuit 42 provided on the secondary side of the transformer 32, and the rectifier circuits 41 and 42. And a smoothing circuit 5 connected to the.

  The input smoothing capacitor 2 is for smoothing the DC input voltage Vin input from the input terminals T1 and T2.

  The inverter circuit 11 has a full-bridge circuit configuration including four switching elements S11 to S14. Specifically, one ends of the switching elements S11 and S12 are connected to each other and one ends of the switching elements S13 and S14 are connected to each other, and these one ends are connected to each other via the primary side winding 311 of the transformer 31. Connected to each other. Further, the other ends of the switching elements S11 and S13 are connected to each other and the other ends of the switching elements S12 and S14 are connected to each other, and these other ends are connected to the input terminals T1 and T2, respectively. With such a configuration, the inverter circuit 11 converts the DC input voltage Vin applied between the input terminals T1 and T2 into an input AC voltage in accordance with a drive signal supplied from a drive circuit (not shown). .

  The inverter circuit 12 also has a full-bridge circuit configuration including four switching elements S21 to S24. Specifically, one ends of the switching elements S21 and S22 are connected to each other and one ends of the switching elements S23 and S24 are connected to each other, and these one ends are connected to each other via the primary side winding 321 of the transformer 32. Are connected to each other. The other ends of the switching elements S21 and S23 are connected to each other, and the other ends of the switching elements S22 and S24 are connected to each other, and the other ends are connected to the input terminals T1 and T2, respectively. With this configuration, the inverter circuit 12 also converts the DC input voltage Vin applied between the input terminals T1 and T2 into an input AC voltage in accordance with a drive signal supplied from a drive circuit (not shown). .

  In addition, as these switching elements S11-S14, S21-S24, switch elements, such as a field effect transistor (MOS-FET; Metal Oxide Semiconductor-Field Effect Transistor) and IGBT (Insulated Gate Bipolor Transistor), are used, for example.

  One ends of the pair of secondary windings 312A and 312B of the transformer 31 are connected to each other by a center tap P1, and a wiring from the center tap P1 is led to a terminal TL1 of the smoothing circuit 5. The transformer 31 transforms the input AC voltage generated by the inverter circuit 11 and is 180 degrees from each end (end opposite to the center tap P1) of the pair of secondary windings 312A and 312B. Output AC voltages with different phases are output. In this case, the degree of transformation is determined by the turn ratio between the primary winding 311 and the secondary windings 312A and 312B.

  One ends of the pair of secondary windings 322A and 322B of the transformer 32 are connected to each other by a center tap P3, and wiring from the center tap P3 is led to a terminal TL3 of the smoothing circuit 5. The transformer 32 transforms the input AC voltage generated by the inverter circuit 12 and is 180 degrees from each end (the end opposite to the center tap P3) of the pair of secondary windings 322A and 322B. Output AC voltages with different phases are output. Note that the degree of transformation in this case is determined by the turn ratio between the primary winding 321 and the secondary windings 322A and 322B.

  The rectifier circuit 41 is a single-phase full-wave rectifier type composed of a pair of rectifier diodes 41A and 41B. The cathode of the rectifier diode 41A is connected to the other end of the secondary winding 312A of the transformer 31, and the cathode of the rectifier diode 41B is connected to the other end of the secondary winding 312B of the transformer 31. The anodes of the rectifier diodes 41A and 41B are connected to each other at the connection point P2, and are led to the terminal TL2 of the smoothing circuit 5. That is, this rectifier circuit 41 has a center tap type anode common connection configuration, and each half-wave period of the output AC voltage from the transformer 31 is individually rectified by the rectifier diodes 41A and 41B to generate a DC voltage. To get.

  The rectifier circuit 42 is also a single-phase full-wave rectifier type composed of a pair of rectifier diodes 42A and 42B. The cathode of the rectifier diode 42A is connected to the other end of the secondary winding 322A of the transformer 32, and the cathode of the rectifier diode 42B is connected to the other end of the secondary winding 322B of the transformer 32. The anodes of the rectifier diodes 42A and 42B are connected to each other at the connection point P4 and led to the terminal TL4 of the smoothing circuit 5. That is, this rectifier circuit 42 is also configured to be center tap type anode common connection, and each half wave period of the output AC voltage from the transformer 32 is individually rectified by the rectifier diodes 42A and 42B to generate the DC voltage. To get.

  The smoothing circuit 5 includes a core member (not shown), choke coils 5L1 to 5L4, 5Lc1 and 5Lc2, and an output smoothing capacitor 5C. The choke coil 5L1 is inserted and arranged on the output line LO (a line connecting the connection point P51 and the output terminal T3 and supplying an output current to the load 6), and one end of the choke coil 5L1 is connected to the terminal TL1. The other end is connected to the connection point P51. The choke coil 5L2 is inserted and arranged on the ground line LG (a ground line connecting the connection point P52 and the output terminal T4), one end is connected to the terminal TL2, and the other end is connected to the connection point P52. Yes. The choke coil 5L3 is inserted and disposed on the output line LO, and one end is connected to the terminal TL3 and the other end is connected to the connection point P51. The choke coil 5L4 is inserted and disposed on the ground line LG, and one end is connected to the terminal TL4 and the other end is connected to the connection point P52. The choke coil 5Lc1 is inserted and arranged on the output line LO, and one end is connected to the connection point P51 and the other end is connected to the connection point P53 (one end of the output smoothing capacitor 5C). The choke coil 5Lc2 is inserted and disposed on the ground line LG, and one end is connected to the connection point P52 and the other end is connected to the connection point P54 (the other end of the output smoothing capacitor 5C). The choke coil 5L1 and the choke coil 5L2 are magnetically coupled by the first magnetic cores UC1 and DC1 (details will be described later) of the core members, and the choke coil 5L3 and the choke coil 5L4 are The second magnetic cores UC2 and DC2 (details will be described later) of the core members are magnetically coupled. The choke coils 5L1, 5Lc1, 5Lc2, and 5L3 are magnetically coupled to each other by common magnetic cores (center magnetic cores) UCc and DCc (details will be described later) of the core members. The smoothing capacitor 5C is connected between the output line LO (specifically, the connection point P53) and the ground line LG (specifically, the connection point P54). An output terminal T3 is provided at the end of the output line LO, and an output terminal T4 is provided at the end of the ground line LG. With such a configuration, the smoothing circuit 5 smoothes the DC voltage rectified by the rectifier circuits 41 and 42 to generate the DC output voltage Vout, and supplies this to the low voltage battery (not shown) from the output terminals T3 and T4. It is supposed to be.

  Next, a detailed configuration of the smoothing circuit 5 which is a main characteristic part of the present invention will be described with reference to FIG. FIG. 2 is a perspective view of the external configuration of the smoothing circuit 5.

  This smoothing circuit 5 has a structure in which choke coils 5L1 to 5L4, 5Lc1 and 5Lc2 are wound around a core material U which is an EE core composed of an upper E core UC and a lower E core DC facing each other. It has become. The upper E-type core UC and the lower E-type core DC are each made of a magnetic material such as ferrite, and the choke coils 5L1 to 5L4, 5Lc1 and 5Lc2 are made of a conductive material such as copper and aluminum, for example. .

  The upper E-type core UC includes a base core UCb, and a first magnetic core UC1, a second magnetic core UC2, and a common magnetic core (central magnetic core) UCc that are three leg portions extending from the base core UCb. It is configured. The lower E-type core DC is composed of a base core DCb, and a first magnetic core DC1, a second magnetic core DC2, and a common magnetic core (center magnetic core) DCc that are three leg portions extending from the base core DCb. It is configured. It should be noted that a predetermined gap may be provided between the common magnetic cores UCc and DCc, between the first magnetic cores UC1 and DC1, and between the second magnetic cores UC2 and DC2. Specifically, a predetermined gap may be provided only between the common magnetic cores UCc and DCc, or a predetermined gap may be provided only between the first magnetic cores UC1 and DC1 and between the second magnetic cores UC2 and DC2. Alternatively, a predetermined gap may be provided between the common magnetic cores UCc and DCc, between the first magnetic cores UC1 and DC1, and between the second magnetic cores UC2 and DC2. In addition, it is difficult to put a completely equivalent gap in both outer legs (first magnetic cores UC1, DC1 and second magnetic cores UC2, DC2) to which magnetic flux is divided, but the central magnetic core (common magnetic core) If the cores UCc and DCc), the magnetic flux flows in common, resulting in a completely equivalent gap for both loops.

  One end of the choke coil 5L1 is connected to the terminal TL1, and the other end is connected to the connection point P51 by being wound around the first magnetic cores UC1 and DC1 by one turn clockwise as viewed from above. It is connected. The choke coil 5L2 has one end connected to the terminal TL2, and is wound around the first magnetic cores UC1 and DC1 by one turn counterclockwise as viewed from above in the figure, so that the other end is connected to the connection point. It is connected to P52. The choke coil 5L3 is connected at one end to the terminal TL3 and wound around the second magnetic cores UC2 and DC2 by one turn clockwise as viewed from above in the drawing, so that the other end is connected to the connection point. Connected to P51. The choke coil 5L4 has one end connected to the terminal TL4 and wound around the second magnetic cores UC2 and DC2 by one turn counterclockwise as viewed from above in the figure, so that the other end is connected to the connection point. It is connected to P52.

  As shown in FIG. 1, one end of the choke coil 5L1 is connected to the connection point P1 (center tap) via the terminal TL1, and one end of the choke coil 5L2 is connected to the connection point P2 via the terminal TL2. One end of the choke coil 5L3 is connected to the connection point P3 (center tap) via the terminal TL3, and one end of the choke coil 5L4 is connected to the connection point P4 via the terminal TL4.

  The other ends of the choke coils 5L1 and 5L3 are connected to each other at the connection point P51 and are connected to one end of the choke coil 5Lc1. The choke coil 5Lc1 is wound around the common magnetic cores UCc and DCc by 0.5 turns counterclockwise when viewed from above (as viewed from above, the vicinity of the right side surface of the common magnetic cores UCc and DCc). The other end is connected to one end (connection point P53) of the output smoothing capacitor 5C. The other ends of the choke coils 5L2 and 5L4 are connected to each other at the connection point P52 and are connected to one end of the choke coil 5Lc2. The choke coil 5Lc2 is wound around the common magnetic cores UCc and DCc by 0.5 turns clockwise as viewed from above (in the vicinity of the left side surface of the common magnetic cores UCc and DCc as viewed from above). The other end is connected to the other end (connection point P54) of the output smoothing capacitor 5C.

  Although details will be described later, a predetermined return magnetic path or the like is formed by the current flowing through the choke coils 5L1 to 5L4 and the choke coils 5Lc1 and 5Lc2.

  Here, the output smoothing capacitor 5C corresponds to a specific example of “capacitance element” in the present invention. Further, the choke coil 5L1 corresponds to a specific example of “first winding” in the present invention, the choke coil 5L2 corresponds to a specific example of “second winding” in the present invention, and the choke coil 5L3 includes The choke coil 5L4 corresponds to a specific example of the “third winding” in the present invention, and the choke coil 5L4 corresponds to a specific example of the “fourth winding” in the present invention. Further, the choke coil 5Lc1 corresponds to a specific example of “first common winding” in the present invention, and the choke coil 5Lc2 corresponds to a specific example of “second common winding” in the present invention. Further, the rectifier circuit 41 corresponds to a specific example of “first rectifier circuit” in the present invention, and the rectifier circuit 42 corresponds to a specific example of “second rectifier circuit” in the present invention. Further, the connection point P1 (center tap) corresponds to a specific example of “a current outflow end in the first rectifier circuit” in the present invention, and the connection point P2 is “a current inflow end of the first rectifier circuit” in the present invention. The connection point P3 (center tap) corresponds to a specific example of “current outflow end in the second rectifier circuit” in the present invention, and the connection point P4 corresponds to “second rectification in the present invention. This corresponds to a specific example of “the current inflow end of the circuit”.

  Next, the operation of the switching power supply device 1 according to the present embodiment will be described with reference to FIGS.

  First, the basic operation of the switching power supply device 1 will be described with reference to FIGS. 3 and 4.

  In this switching power supply device 1, in the inverter circuit 11, the DC input voltage Vin supplied from the input terminals T <b> 1 and T <b> 2 is switched to generate an input AC voltage, and this input AC voltage is converted into the primary side winding 311 of the transformer 31. Supplied to. The transformer 31 transforms the input AC voltage, and the transformed output AC voltage is output from the secondary windings 312A and 312B. Similarly, in the inverter circuit 12, the DC input voltage Vin supplied from the input terminals T 1 and T 2 is switched to generate an input AC voltage, and this input AC voltage is supplied to the primary winding 321 of the transformer 32. . The transformer 32 transforms the input AC voltage, and the transformed output AC voltage is output from the secondary windings 322A and 322B.

  In the rectifier circuit 41, the output AC voltage output from the transformer 31 is rectified by the rectifier diodes 41A and 41B. As a result, a rectified output is generated between the center tap P1 and the connection point P2 of the rectifier diodes 41A and 41B. Similarly, in the rectifier circuit 42, the output AC voltage output from the transformer 32 is rectified by the rectifier diodes 42A and 42B. As a result, a rectified output is generated between the center tap P3 and the connection point P4 of the rectifier diodes 42A and 42B.

  In the smoothing circuit 5, the rectified outputs generated in the rectifying circuits 41 and 42 are smoothed by the choke coils 5L1 to 5L4, 5Lc1 and 5Lc2 and the output smoothing capacitor 5C, and output as the DC output voltage Vout from the output terminals T3 and T4. Is done. The DC output voltage Vout is fed to a low-voltage battery (not shown) to be charged, and the load 6 is driven.

  Further, in the switching power supply device 1 of the present embodiment, in the inverter circuits 11 and 12, the switching elements S11 and S14 and the switching elements S21 and S24 are turned on, the switching elements S12 and S13, and the switching elements S22 and S22, respectively. The period in which S23 is turned on is repeated alternately. Therefore, the operation of the switching power supply device 1 will be described in detail as follows.

  First, as shown in FIG. 3, when the switching elements S11 and S14 of the inverter circuit 11 and the switching elements S21 and S24 of the inverter circuit 12 are turned on, the primary loop in the direction from the switching element S11 to the switching element S14 is performed. While the current Ia11 flows, the primary loop current Ia12 flows in the direction from the switching element S21 to the switching element S24. Then, the voltages appearing in the secondary windings 312A and 312B of the transformer 31 are in the reverse direction with respect to the rectifier diode 41B, while in the forward direction with respect to the rectifier diode 41A. Therefore, a secondary loop current Ia21 flows from the rectifier diode 41A through the secondary winding 312A, the choke coils 5L1 and 5Lc1, the output smoothing capacitor 5C, and the choke coils 5Lc2 and 5L2. Similarly, the voltages appearing on the secondary windings 322A and 322B of the transformer 32 are in the reverse direction with respect to the rectifier diode 42B, while in the forward direction with respect to the rectifier diode 42A. For this reason, the secondary side loop current Ia22 that flows from the rectifier diode 42A in order to the secondary side winding 322A, the choke coils 5L3 and 5Lc1, the output smoothing capacitor 5C, and the choke coils 5Lc2 and 5L4 flows. The secondary side loop currents Ia21 and Ia22 feed the DC output voltage Vout to a low-voltage battery (not shown) and drive the load 6.

  On the other hand, as shown in FIG. 4, the switching elements S11 and S14 of the inverter circuit 11 and the switching elements S21 and S24 of the inverter circuit 12 are turned off, and the switching elements S12 and S13 of the inverter circuit 11 and the inverter circuit 12 When the switching elements S23 and S23 are turned on, the primary loop current Ib11 flows in the direction from the switching element S13 to the switching element S12, and the primary loop current Ib12 flows in the direction from the switching element S23 to the switching element S22. Flowing. Then, the voltages appearing on the secondary windings 312A and 312B of the transformer 31 are in the reverse direction with respect to the rectifier diode 41A, and are in the forward direction with respect to the rectifier diode 41B. Therefore, a secondary loop current Ib21 flows from the rectifier diode 41B through the secondary winding 312B, the choke coils 5L1 and 5Lc1, the output smoothing capacitor 5C, and the choke coils 5Lc2 and 5L2. Similarly, the voltages appearing in the secondary windings 322A and 322B of the transformer 32 are in the reverse direction with respect to the rectifier diode 42A, and are in the forward direction with respect to the rectifier diode 42B. Therefore, a secondary loop current Ib22 flows from the rectifier diode 42B through the secondary winding 322B, the choke coils 5L3 and 5Lc1, the output smoothing capacitor 5C, and the choke coils 5Lc2 and 5L4 in this order. The DC output voltage Vout is fed to a low-voltage battery (not shown) and the load 6 is driven by these secondary loop currents Ib21 and Ib22.

  Next, with reference to FIG. 5, the operation of the characteristic part in the switching power supply device 1 of the present embodiment will be described in detail.

  In the switching power supply 1, in the smoothing circuit 5 having the configuration shown in FIGS. 1 and 2, as shown in FIGS. 3 and 4, each choke coil 5L1 to 5L4, 5Lc1, 5Lc2 and the output smoothing capacitor 5C are supplied with current ( When the secondary loop currents Ia21, Ia22, Ib21, Ib22) flow, the core material U forms a magnetic path as shown in FIG. That is, in the smoothing circuit 5, the choke coils 5L1 to 5L4 and the choke coils 5Lc1 and 5Lc2 are, as shown in FIG. 2, the first magnetic cores UC1 and DC1, the second magnetic cores UC2 and DC2, and the common magnetic core UCc. , DCc, and the first annular magnet passing through the first magnetic cores UC1, DC1 and the common magnetic cores UCc, DCc by the current flowing through the choke coil 5L1 and the current flowing through the choke coil 5L2 A path B1 is formed, and in synchronization with the current flowing through the choke coil 5L1 and the current flowing through the choke coil 5L2, the current flows through the choke coils 5L3 and 5L4, respectively, and the current flowing through the choke coil 5L3 and the choke coil 5L4 are The second magnetic cores UC2 and DC2 and the common magnetic cores UCc and DC depending on the flowing current. Second annular path B2 passing through the inside is formed. Further, the magnetic fluxes in the first return magnetic path B1 and the second return magnetic path B2 have the same direction in the common magnetic cores UCc and DCc.

  Thus, in the smoothing circuit 5 of the present embodiment, the magnetic flux formed by the magnetic flux in the first annular magnetic path B1, the magnetic flux in the second annular magnetic path B2, the current flowing through the choke coil 5Lc1, and the choke coil The magnetic flux formed by the current flowing through 5Lc2 has the same direction and is shared with each other inside the common magnetic cores UCc and DCc. As a result, the current flowing through the choke coils 5L1 and 5L3 and the current flowing through the choke coils 5L2 and 5L4 are balanced and stabilized.

  Further, since such a balanced state is automatically maintained in the smoothing circuit 5, adjustment of element characteristic values and the like is not necessary.

  As described above, in the present embodiment, in the smoothing circuit 5, the magnetic flux formed by the magnetic flux in the first annular magnetic path B1, the magnetic flux in the second annular magnetic path B2, the current flowing through the choke coil 5Lc1, and the choke coil Since the magnetic flux formed by the current flowing through 5Lc2 is shared in the common magnetic cores UCc and DCc with the same direction, the current flowing through the choke coils 5L1 and 5L2 and the choke coil 5L3 are shared. , 5L4 can be balanced and stabilized. Further, since the smoothing circuit 5 automatically maintains such an equilibrium state, it is not necessary to adjust the characteristic value of the element, and a large margin is not required for the characteristic value of the element. Therefore, it is possible to supply a stable output while suppressing the manufacturing cost.

  Further, one end of the choke coil 5L1 is connected to the connection point P1 (center tap) through the terminal TL1, one end of the choke coil 5L2 is connected to the connection point P2 through the terminal TL2, and one end of the choke coil 5L3 is connected to the connection point P1. Since the terminal TL3 is connected to the connection point P3 (center tap) and one end of the choke coil 5L4 is connected to the connection point P4 via the terminal TL4, the above-described effects can be obtained. .

  Further, the core member U is constituted by an EE core having two return magnetic paths B1 and B2 via the common magnetic cores UCc and DCc, and the first magnetic core UC1 outside the common magnetic cores UCc and DCc. , DC1 and the second magnetic cores UC2 and DC2 are wound with windings, so that the core overlaps the windings as compared with the case where windings are wound only on the common magnetic cores UCc and DCc. The area can be reduced, and the heat radiation area of the choke coils 5L1 to 5L4, 5Lc1 and 5Lc2 can be further increased. Therefore, since the heat dissipation characteristics are improved, the choke coils 5L1 to 5L4, 5Lc1 and 5Lc2 can be stabilized.

  Hereinafter, some modified examples of the present invention will be described. In addition, the same code | symbol is attached | subjected to the same thing as the component in the said embodiment, and description is abbreviate | omitted suitably.

[Modification 1]
6 and 7 illustrate a circuit configuration of a switching power supply device (switching power supply device 1A) according to the first modification. This switching power supply device 1A is obtained by changing the connection relationship between the rectifier circuits 41 and 42 and the smoothing circuit 5 in the switching power supply device 1 described in the above embodiment. Specifically, one end of the choke coil 5L1 is connected to the connection point P3 (center tap) via the terminal TL1, and one end of the choke coil 5L2 is connected to the connection point P2 via the terminal TL2, and the choke coil 5L3 Is connected to the connection point P1 (center tap) via the terminal TL3, and one end of the choke coil 5L4 is connected to the connection point P4 via the terminal TL4. That is, in the switching power supply device 1 described in the above embodiment, the connection relationship between the terminals TL1, TL3 and the connection points P1, P3 is exchanged.

  With such a configuration, in the switching power supply device 1A of the present modification example, the secondary side loop current Ia23, as shown in FIG. 6, on the secondary side of the transformers 31 and 32, based on the primary side loop currents Ia11 and Ia12. While Ia24 flows, secondary side loop currents Ib23 and Ib24 as shown in FIG. 7 flow based on the primary side loop currents Ib11 and Ib12.

  Thus, also in this modification, in the smoothing circuit 5, the magnetic flux formed by the magnetic flux in the first annular magnetic path B1, the magnetic flux in the second annular magnetic path B2, the current flowing through the choke coil 5Lc1, and the choke coil Since the magnetic flux formed by the current flowing through 5Lc2 is shared with each other in the common magnetic cores UCc and DCc, it is possible to supply a stable output while suppressing the manufacturing cost.

[Modification 2]
FIG. 8 illustrates a circuit configuration of a switching power supply device (switching power supply device 1B) according to the second modification. In the switching power supply device 1A, in the switching power supply device 1 described in the above embodiment, the transformers 31B and 32B have a pair of secondary windings 312A and 312B and a pair of secondary windings 322A and 322B, respectively. In addition, a rectifier circuit connected to one secondary winding 312A of the transformer 31B and the other secondary winding 322B of the transformer 32B, and the other secondary winding 312B of the transformer 31B and the transformer 32B is configured by a rectifier circuit connected to one secondary winding 322A. One end of the choke coil 5L1 is connected to the connection point P6 via the terminal TL1, one end of the choke coil 5L2 is connected to the connection point P2 via the terminal TL2, and one end of the choke coil 5L3 is connected to the terminal TL3. And one end of the choke coil 5L4 is connected to the connection point P4 via the terminal TL4.

  The transformer 31B corresponds to a specific example of “first transformer” in the present invention, and the transformer 32B corresponds to a specific example of “second transformer” in the present invention. The connection point P6 corresponds to the “current outflow end of the first rectifier circuit” in the present invention, and the connection point P7 corresponds to the “current outflow end of the second rectifier circuit” in the present invention.

  With such a configuration, also in the present modification, in the smoothing circuit 5, the magnetic flux formed by the magnetic flux in the first annular magnetic path B1, the magnetic flux in the second annular magnetic path B2, the current flowing through the choke coil 5Lc1, and the choke Since the magnetic flux formed by the current flowing through the coil 5Lc2 is shared with each other inside the common magnetic cores UCc and DCc, it is possible to supply a stable output while suppressing the manufacturing cost. .

[Modification 3]
FIG. 9 illustrates a circuit configuration of a switching power supply device (switching power supply device 1 </ b> C) according to the third modification. In this switching power supply device 1C, the transformers 31C and 32C are connected in series with each other, and a pair of primary windings 311A and 311B and a primary side in which alternating current resistance during switching operation by the inverter circuits 11 and 12 is alternately increased. Windings 321A and 321B are provided.

  With this configuration, in the switching power supply 1C of the present modification, as shown in the figure, the primary windings 311A, 311B, 321A, 321B and the secondary windings 312A, 312B, When currents in opposite directions flow between 322A and 322B, the AC resistance is lowered due to the skin effect and the proximity effect. Specifically, when the primary side loop currents Ia11 and Ia12 are flowing through the primary side windings 311A and 311B and the primary side windings 321A and 321B, the secondary side loop currents Ia21 and Ia22 flow. In the primary side windings 311A and 321A arranged near the windings 312A and 322A, the directions of the currents of the primary side loop currents Ia11 and Ia12 and the secondary side loop currents Ia21 and Ia22 are opposite to each other. Therefore, in these primary side windings 311A and 321A, the AC resistance is lowered due to the skin effect and the proximity effect, compared to the case where the windings having the same current direction are brought close to each other. Further, when the primary loop currents Ib11 and Ib12 are flowing through the primary windings 311A and 311B and the primary windings 321A and 321B, the secondary winding 312B through which the secondary loop currents Ib21 and Ib22 flow is provided. , 322B, the primary side windings 311B and 321B are arranged in such a manner that the directions of the primary side loop currents Ib11 and Ib12 and the secondary side loop currents Ib21 and Ib22 are opposite to each other. In the primary side windings 311B and 321B, the AC resistance is lowered due to the skin effect and the proximity effect as compared with the case where windings having the same current direction are brought close to each other. As a result, the oscillation component is absorbed by the primary side winding having a relatively high AC resistance, so that ringing of the output can be suppressed.

  As described above, in this modified example, in addition to the effects in the above embodiment, ringing of output can be suppressed, and output can be further stabilized.

[Modification 4]
FIG. 10 illustrates a circuit configuration of a switching power supply device (switching power supply device 1D) according to Modification 4. This switching power supply device 1D is the same as the switching power supply device 1C described in the third modification, but includes a pair of primary windings 311A, 311B and primary windings 321A in the inverter circuits 11, 12 and transformers 31D, 32D. The connection relationship with 321B is interchanged.

  With such a configuration, also in the present modification, in the smoothing circuit 5, the magnetic flux formed by the magnetic flux in the first annular magnetic path B1, the magnetic flux in the second annular magnetic path B2, the current flowing through the choke coil 5Lc1, and the choke Since the magnetic flux formed by the current flowing through the coil 5Lc2 is shared with each other inside the common magnetic cores UCc and DCc, it is possible to supply a stable output while suppressing the manufacturing cost. .

[Modification 5]
FIG. 11 illustrates a circuit configuration of a switching power supply device (switching power supply device 1E) according to Modification 5. This switching power supply device 1E is configured such that, in the switching power supply device 1 described in the above embodiment, the inverter circuit arranged on the primary side of the transformers 31 and 32 is configured by a single inverter circuit 10E. is there.

  With such a configuration, also in the present modification, in the smoothing circuit 5, the magnetic flux formed by the magnetic flux in the first annular magnetic path B1, the magnetic flux in the second annular magnetic path B2, the current flowing through the choke coil 5Lc1, and the choke Since the magnetic flux formed by the current flowing through the coil 5Lc2 is shared with each other inside the common magnetic cores UCc and DCc, it is possible to supply a stable output while suppressing the manufacturing cost. .

  In addition, as compared with the case where the inverter circuit is configured by a plurality of inverter circuits 11 and 12 as in the above embodiment, the circuit configuration is simplified and the manufacturing cost can be further suppressed.

[Modification 6]
FIG. 12 illustrates a circuit configuration of a switching power supply device (switching power supply device 1F) according to Modification 6. This switching power supply device 1F is obtained by providing rectifier circuits (switching circuits) 41F and 42F instead of the rectifier circuits 41 and 42 in the switching power supply device 1 described in the above embodiment.

  In the rectifier circuits 41F and 42F, FETs (field effect transistors) are used as rectifier elements. In other words, the rectifier diode has been described as an example of the rectifier so far, but in the present modification, an FET is used as the rectifier. As a result, the rectifier diode elements 41A, 41B, 42A, and 42B in the above embodiment are replaced with the switching elements S41A, S41B, S42A, and S42B, and the rectifier diodes D41A, D41B, D42A, and D42B connected in parallel to them (switching element S41A). , S41B, S42A, and S42B parasitic diodes).

  With this configuration, in this modified example, by performing the synchronous rectification operation in the rectifier circuits 41F and 42F, it is possible to improve the efficiency of the circuit as compared with the above-described embodiment and the like.

[Modification 7]
FIG. 13 illustrates a circuit configuration of a switching power supply device (switching power supply device 1G) according to Modification 7. The switching power supply device 1G is provided with the switching circuits 41F and 42F described in the modification 7 in place of the rectifier circuits 41 and 42 in the switching power supply device 1 described in the above embodiment, and the inverter circuits 11 and 12 Instead of these, switching circuits 11G and 12G are provided.

  In the switching circuits 11G and 12G, the switching elements S11 to S14 in the above embodiment are configured by MOS-FETs or the like. Thereby, in switching circuit 11G, 12G, switching element S11-S14 in the said embodiment is switching element S11-S14 and the rectifier diode D11-D14 (parasitic diode of switching element S11-S14) connected in parallel to them. It can be regarded as consisting of

  With this configuration, in this modification, the DC input voltage Vin input from the input terminals T1 and T2 is stepped down as described in the above embodiment, and the DC output voltage Vout is output from the output terminals T3 and T4. In addition to the step-down operation, the step-up operation of boosting the DC input voltage Vin input from the output terminals T3 and T4 and outputting the DC output voltage Vout from the input terminals T1 and T2 as described below can be performed. (Bidirectional operation is possible). In that case, during the step-down operation (forward operation), the switching circuits 11G and 12G function as an inverter circuit and the switching circuits 41F and 42F function as a rectifier circuit, and during the step-up operation (reverse operation). The switching circuits 41F and 42F function as an inverter circuit, and the switching circuits 11G and 12G function as a rectifier circuit.

  Here, the input terminals T1 and T2 correspond to a specific example of “first input / output terminal” in the present invention, and the output terminals T3 and T4 correspond to a specific example of “second input / output terminal” in the present invention. Correspond. The switching circuits 11G and 12G correspond to a specific example of “first circuit” in the present invention, and the switching circuits 41F and 42F correspond to a specific example of “two second circuits” in the present invention. Further, the switching elements S11 to S14 and S21 to S24 correspond to a specific example of “first switching element” in the present invention, and the rectifier diodes D11 to D14 and D21 to D24 are “first rectifier element” in the present invention. This corresponds to a specific example. The switching elements S41A, S41B, S42A, and S42B correspond to a specific example of “second switching element” in the present invention, and the rectifier diodes D41A, D41B, D42A, and D42B are “second rectifier elements” in the present invention. This corresponds to a specific example.

  Note that during the above-described step-up operation (reverse operation), the drive signals of the switching elements S11 to S14 and S21 to S24 are always 0V, and the switching elements S11 to S14 and S21 to S24 are always in the OFF state. Become. However, when performing the above-described synchronous rectification, the switching elements S11 to S14 and S21 to S24 are also turned on / off, and the loss is smaller than in the case of the rectifier diode. In the following FIG. 14 to FIG. 16, the case where the switching elements S11 to S14 and S21 to S24 perform such synchronous rectification will be described.

  First, as shown in FIG. 14, the switching elements S41A and S42A and the switching elements S41B and S42B are both turned on. Therefore, on the low voltage side including the switching circuits 41F and 42F, loop currents Ic11, Ic12, Id11 and Id12 as shown in the figure flow from the low voltage battery 70, and the choke coils 5L1 to 5L4, 5Lc1 and 5Lc2 are excited. . In addition, since the windings 312A and 312B in the transformer 31 and the windings 322A and 322B in the transformer 32 have opposite winding directions and the same number of turns, the currents flowing through the windings 312A and 312B and the windings 322A and 322B, respectively. Thus, the magnetic fluxes generated by each other cancel each other, and the voltage between both ends of the windings 312A and 312B and between both ends of the windings 322A and 322B is 0V. Therefore, power transmission from the low voltage side to the high voltage side is not performed during this period. However, on the high voltage side, an output current Iout as shown in the figure flows from the input smoothing capacitor 2 to the load L.

  Next, as shown in FIG. 15, only switching elements S41A and S42A are turned off. Therefore, only the loop currents Ic11 and Ic12 as shown in the figure flow on the low voltage side, and power is transmitted from the low voltage side to the high voltage side based on the energy accumulated in the choke coils 5L1 to 5L4, 5Lc1 and 5Lc2. Is made. At this time, in the switching circuit 11G, the switching elements S12 and S13 are turned on and the switching elements S11 and S14 are turned off, so that a synchronous rectification operation is performed. Similarly, in the switching circuit 12G, the switching elements S22 and S23 are turned on and the switching elements S21 and S24 are turned off, so that a synchronous rectification operation is performed. Note that after the period of the operation state shown in FIG. 15, the operation state shown in FIG. 14 is reached again.

  Next, after such a state shown in FIG. 14 again, only the switching elements S41B and S42B are turned off as shown in FIG. Therefore, only the loop currents Id11 and Id12 as shown in the figure flow on the low voltage side, and power is transferred from the low voltage side to the high voltage side based on the energy accumulated in the choke coils 5L1 to 5L4, 5Lc1 and 5Lc2. Is made. At this time, in the switching circuit 11G, the switching elements S11 and S14 are turned on and the switching elements S12 and S13 are turned off, so that the synchronous rectification operation is performed. Similarly, in the switching circuit 12G, the switching elements S21 and S24 are turned on and the switching elements S22 and S23 are turned off, so that a synchronous rectification operation is performed.

  Although the present invention has been described with reference to the embodiment and the modification examples, the present invention is not limited to the embodiment and the like, and various modifications can be made.

  For example, the current flowing through the choke coil 5L1 and the current flowing through the choke coil 5L2, and the current flowing through the choke coil 5L3 and the current flowing through the choke coil 5L4 are literally completely synchronized as described in the above embodiments and the like. It is not limited to the case, and it may be substantially synchronized. Further, the current flowing through the choke coil 5L1 and the current flowing through the choke coil 5L2, or the current flowing through the choke coil 5L3 and the current flowing through the choke coil 5L4 do not need to flow completely at the same time. That's fine.

  Moreover, although the said embodiment etc. demonstrated the case where the core material U was comprised with the EE core, you may comprise with an EI core etc., for example.

  Further, the configuration of the inverter circuit may be a configuration other than a full bridge type (for example, a half bridge type).

  Further, the configuration of the rectifier circuit may be a cathode common connection instead of an anode common connection, or may be a configuration other than the center tap type (for example, a bridge type or a forward type). Further, instead of a full-wave rectification type rectification circuit, a half-wave rectification type rectification circuit may be used.

  Furthermore, you may combine the modification etc. which were demonstrated in the said embodiment etc.

It is a circuit diagram showing the structure of the switching power supply device which concerns on one embodiment of this invention. It is a perspective view showing the external appearance structure of the smoothing circuit shown in FIG. It is a circuit diagram for demonstrating the basic operation | movement of the switching power supply device shown in FIG. It is a circuit diagram for demonstrating the basic operation | movement of the switching power supply device shown in FIG. It is sectional drawing for demonstrating the direction of the electric current and magnetic flux in the core material shown in FIG. It is a circuit diagram showing the structure and basic operation | movement of a switching power supply apparatus which concerns on the modification 1 of this invention. It is a circuit diagram showing the structure and basic operation | movement of a switching power supply apparatus which concerns on the modification 1 of this invention. It is a circuit diagram showing the structure and basic operation | movement of the switching power supply apparatus which concerns on the modification 2 of this invention. It is a circuit diagram showing the structure and basic operation | movement of a switching power supply apparatus which concerns on the modification 3 of this invention. It is a circuit diagram showing the structure and basic operation | movement of a switching power supply apparatus which concerns on the modification 4 of this invention. It is a circuit diagram showing the structure and basic operation | movement of a switching power supply apparatus which concerns on the modification 5 of this invention. It is a circuit diagram showing the structure of the switching power supply device which concerns on the modification 6 of this invention. It is a circuit diagram showing the structure of the switching power supply device which concerns on the modification 7 of this invention. It is a circuit diagram for demonstrating operation | movement of the switching power supply device shown in FIG. It is a circuit diagram for demonstrating operation | movement of the switching power supply device shown in FIG. It is a circuit diagram for demonstrating operation | movement of the switching power supply device shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,1A-1G ... Switching power supply device, 10 ... High voltage battery, 11, 12, 10E ... Inverter circuit, 11G, 12G ... Switching circuit, 2 ... Input smoothing capacitor, 31, 31B, 31C, 31D, 32, 32B, 32C , 32D, 30E ... transformer, 310, 320, 30 ... magnetic core, 311, 311A, 311B, 321, 321A, 321B, 31E ... primary winding, 312A, 312B, 322A, 322B ... secondary winding, 41, 41B, 41F, 42, 42B, 42F ... Rectifier circuit, 41F, 42F ... Rectifier circuit (switching circuit), 41A, 41B, 42A, 42B, D11-D14, D21-D24, D41A, D41B, D42A, D42B ... Rectifier diode, 5 ... smoothing circuit, 5L1 to 5L4, 5Lc1, 5Lc2 ... choke 5C ... Output smoothing capacitor, 6 ... Load, 70 ... Low voltage battery, L1H ... Primary side high voltage line, L1L ... Primary side low voltage line, LO ... Output line, LG ... Ground line, T1, T2 ... Input terminal, T3, T4: Output terminal, TL1 to TL4: Smoothing circuit terminal, S1 to S4, S11 to S14, S21 to S24, S41A, S41B, S42A, S42B ... Switching element, U ... Core material, UC ... Upper E type core , DC ... lower E-type core, UCb, DCb ... base core, UC1, DC1 ... first magnetic core, UC2, DC2 ... second magnetic core, UCc, DCc ... common magnetic core (central magnetic core), P1, P3 ... Connection point (center tap), P2, P4, P51 to P54, P6, P7, P81, P82, P91, P92 ... connection point, Vin ... DC input voltage, Vout ... DC output voltage, Ia1, Ia1 1, Ia12, Ib1, Ib11, Ib12, Ic11, Ic12, Id11, Id12... Current (primary loop current), Ia21, Ia22, Ia23, Ia24, Ib21, Ib22, Ib23, Ib24, Ic21, Ic22, Id21, Id22 ... current (secondary loop current), Iout ... output current, B1 ... first annular magnetic path, B2 ... second annular magnetic path.

Claims (7)

An inverter circuit that generates an input AC voltage by switching a DC input voltage;
A transformer having a primary side winding and a secondary side winding on the inverter circuit side, transforming the input AC voltage and outputting an output AC voltage;
Two rectifier circuits connected in parallel to the secondary side of the transformer, each performing a rectification operation of the output AC voltage;
A smoothing circuit for smoothing output voltages from the two rectifier circuits to generate a DC output voltage,
The smoothing circuit is
A capacitive element;
First and second magnetic cores;
A common magnetic core disposed between the first and second magnetic cores;
One end of which is connected to the rectifier circuit and the first and second windings wound around the first magnetic core;
A third end and a fourth winding wound around the second magnetic core, with one end connected to the rectifier circuit;
Connecting the other ends of the first and third windings and one end of the capacitive element, and a first common winding wound around the common magnetic core;
Connecting the other ends of the second and fourth windings and the other end of the capacitive element, and having a second common winding wound around the common magnetic core,
A first annular magnetic path that passes through the first magnetic core and the common magnetic core is formed by the current flowing through the first winding and the current flowing through the second winding,
In synchronization with the current flowing through the first winding and the current flowing through the second winding, the current flows through the third and fourth windings, and the current flowing through these third windings A second annular magnetic path passing through the second magnetic core and the common magnetic core is formed by the current flowing through the fourth winding;
Due to the magnetic flux in the first annular magnetic path, the magnetic flux in the second annular magnetic path, the magnetic flux formed by the current flowing through the first common winding, and the current flowing through the second common winding. A switching power supply, wherein the magnetic flux formed is shared with each other inside the common magnetic core. The two rectifier circuits are constituted by first and second rectifier circuits each having a current inflow end and a current outflow end,
One end of the first winding is connected to a current outflow end of the first rectifier circuit;
One end of the second winding is connected to the current inflow end of the first rectifier circuit,
One end of the third winding is connected to the current outflow end of the second rectifier circuit,
The switching power supply according to claim 1, wherein one end of the fourth winding is connected to a current inflow end of the second rectifier circuit. The two rectifier circuits are constituted by first and second rectifier circuits each having a current inflow end and a current outflow end,
One end of the first winding is connected to a current outflow end of the second rectifier circuit,
One end of the second winding is connected to the current inflow end of the first rectifier circuit,
One end of the third winding is connected to a current outflow end of the first rectifier circuit,
The switching power supply according to claim 1, wherein one end of the fourth winding is connected to a current inflow end of the second rectifier circuit. The transformer is composed of a first transformer having a pair of secondary windings and a second transformer having a pair of secondary windings,
The two rectifier circuits have a current inflow end and a current outflow end, and are connected to one secondary winding of the first transformer and the other secondary winding of the second transformer. A second rectifier circuit having a current inflow end and a current outflow end and connected to the other secondary winding of the first transformer and one secondary winding of the second transformer. Rectifier circuit and
One end of the first winding is connected to a current outflow end of the first rectifier circuit;
One end of the second winding is connected to the current inflow end of the first rectifier circuit,
One end of the third winding is connected to the current outflow end of the second rectifier circuit,
The switching power supply according to claim 1, wherein one end of the fourth winding is connected to a current inflow end of the second rectifier circuit. 5. The transformer according to claim 1, wherein the transformer includes a pair of primary windings that are connected in series with each other and alternately have an alternating current resistance during switching operation by the inverter circuit. The switching power supply device according to Item 1. The switching power supply device according to any one of claims 1 to 5, wherein the inverter circuit is configured by a single inverter circuit. A switching power supply apparatus that converts a DC input voltage input from one input / output terminal pair of the first and second input / output terminal pairs and outputs a DC output voltage from the other input / output terminal pair. And
A transformer having a first transformer winding disposed on the first input / output terminal pair side and a second transformer winding disposed on the second input / output terminal pair side;
A first circuit disposed on the first transformer winding side and including a plurality of first switching elements and a first rectifier element connected in parallel to each of the plurality of first switching elements;
Two second elements each disposed on the second transformer winding side, each including a plurality of second switching elements and a second rectifying element connected in parallel to each of the plurality of second switching elements. And the circuit
A smoothing circuit disposed between the two second circuits and the second input / output terminal pair;
The smoothing circuit is
A capacitive element;
First and second magnetic cores;
A common magnetic core disposed between the first and second magnetic cores;
One end connected to the second circuit and the first and second windings wound around the first magnetic core;
A third end and a fourth winding wound around the second magnetic core and having one end connected to the second circuit;
Connecting the other ends of the first and third windings and one end of the capacitive element, and a first common winding wound around the common magnetic core;
Connecting the other ends of the second and fourth windings and the other end of the capacitive element, and having a second common winding wound around the common magnetic core,
A first annular magnetic path that passes through the first magnetic core and the common magnetic core is formed by the current flowing through the first winding and the current flowing through the second winding,
In synchronization with the current flowing through the first winding and the current flowing through the second winding, the current flows through the third and fourth windings, and the current flowing through these third windings A second annular magnetic path passing through the second magnetic core and the common magnetic core is formed by the current flowing through the fourth winding;
Due to the magnetic flux in the first annular magnetic path, the magnetic flux in the second annular magnetic path, the magnetic flux formed by the current flowing through the first common winding, and the current flowing through the second common winding. A switching power supply, wherein the magnetic flux formed is shared with each other inside the common magnetic core.

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