JP2007236092A - Switching power supply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a switching power supply which can widen the convertible voltage range. <P>SOLUTION: The switching power supply is provided with a transformer 3 which has four coils 31A-31D on high voltage side mutually equal in number of turns, corresponding to four switching circuits 11-14 operating synchronously with one another, and four inductors Lr1-Lr4. Four fellow current paths are put each in four parallel connection, in four series connection, or in mixed connection (two series and two parallel connection) of series and parallel, according to the target voltage value of input voltage (DC high voltage VH) at normal operation and output voltage (DC high voltage VH) at reverse operation, by a voltage detecting circuit 61, a controller 7, and connection changeover switches S51-S53 and S61-S63. The ratio of the numbers of turns between the coils 31A-31D on high voltage side and the coils 32A and 32B on low voltage side becomes larger in the order of four parallel connection, two series two parallel connection, and four series connection. Moreover, the current change within the circuit becomes slow by the action of inductors Lr1-Lr4. <P>COPYRIGHT: (C)2007,JPO&INPIT

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 types of switching power supply devices have been proposed and put into practical use. Most of them are systems in which a DC input voltage is switched by a switching operation of a switch circuit connected to an input winding of a power conversion transformer and a switching output is taken out to an output winding of the power conversion transformer. Along with the switching operation of such a switch circuit, the voltage appearing in the output winding is rectified by the rectifier circuit, then converted into direct current by the smoothing circuit and output.

  In this type of switching power supply device, it is desired to widen the input voltage range in which a constant output voltage can be maintained. Therefore, for example, in Patent Document 1, two windings having the same number of turns are provided on the primary side of the transformer corresponding to two switching elements (switching circuits), and these two primary side windings are provided according to the magnitude of the input voltage. There has been proposed a switching power supply device in which wires are connected in series or in parallel.

Japanese Patent Laid-Open No. 11-136939

  According to the technique disclosed in Patent Document 1, the turn ratio between the primary side winding and the secondary side winding of the transformer can be switched according to the magnitude of the input voltage, and an input capable of maintaining a constant output voltage. The voltage range is considered to be wide.

  However, in this switching power supply device, there are only two connection states between the windings, a series connection state and a parallel connection state, and it is difficult to sufficiently expand the convertible voltage range.

  Also, in this switching power supply device, when two primary windings are connected in parallel, the control timing between two switching circuits operating in parallel (timing of ON / OFF operation between switching elements) is between elements. However, there is a problem that an excessive surge current flows due to a difference in impedance between the switching circuits. If an excessive surge current is generated, the switching element or the like may be destroyed. In reality, it is difficult to make the control timings coincide completely. Therefore, as a result, an element having a large current capacity must be used, and the element tends to increase in size as the current capacity increases, making it difficult to downsize the entire apparatus.

  The present invention has been made in view of such problems, and a first object thereof is to provide a switching power supply device capable of further widening a convertible voltage range.

  A second object of the present invention is to provide a switching power supply device that realizes a wide conversion voltage range while suppressing generation of surge current.

  The first switching power supply device of the present invention includes first and second terminal pairs, and is between the first DC voltage on the first terminal side and the second DC voltage on the second terminal pair side. A plurality of first windings arranged on the first terminal pair side and having the same number of turns, and a second winding arranged on the second terminal pair side. And a plurality of first circuits of a full bridge type provided on the first terminal pair side corresponding to the plurality of first windings, each including four switching elements, and the plurality of first coils Connection switching so that a plurality of current paths composed of one circuit and a first winding corresponding to each of the plurality of first circuits are connected in parallel, in series, or mixed in series and parallel And a connection switching means for performing.

  In the first switching power supply of the present invention, each of the plurality of first circuits functions as an inverter circuit or a rectifier circuit, and the first DC voltage and the second voltage on the first terminal side are transformed by a transformer action of the transformer. Voltage conversion is performed with the second DC voltage on the terminal side. Further, connection switching is performed by the connection switching means so that the plurality of current paths are connected in parallel, in series, or mixed in series and parallel. Here, since the plurality of first windings of the transformer respectively correspond to the plurality of first circuits and have the same number of turns, the turn ratio between the first winding and the second winding is parallel. The connection increases in the order of the mixed connection and the serial connection.

  In the first switching power supply device of the present invention, when the input first DC voltage is voltage-converted and the second DC voltage is output, that is, when the plurality of first circuits function as inverter circuits, respectively. Alternatively, the connection switching means may perform connection switching according to the magnitude of the first DC voltage. Specifically, the connection switching means may perform connection switching in the order of parallel connection, mixed connection, and series connection as the first DC voltage increases. When configured in this manner, the turn ratio of the first winding and the second winding increases as the first DC voltage increases, so that a constant output voltage (second DC voltage) is maintained. The range of possible input voltages (first DC voltage) is wider than in the past.

  On the contrary, when the second DC voltage inputted in reverse is converted to output the first DC voltage, that is, when the plurality of first circuits function as rectifier circuits, the connection switching means. However, connection switching may be performed according to the magnitude of the second DC voltage. Specifically, the connection switching unit may perform connection switching in the order of series connection, mixed connection, and parallel connection as the second DC voltage increases. In this configuration, the turn ratio between the first winding and the second winding decreases as the second DC voltage increases, so that a constant output voltage (first DC voltage) is maintained. The range of possible input voltage (second DC voltage) is wider than in the past.

  In these cases, the connection switching means includes a plurality of connection switching elements, a voltage detection circuit for detecting the first DC voltage or the second DC voltage, and a first detected by the voltage detection circuit. Or it is possible to comprise from the 1st control part which controls the ON / OFF state of said several connection switching element according to the magnitude | size of a 2nd DC voltage, respectively.

  In the first switching power supply device of the present invention, the connection switching means compares the magnitudes of the values between the first or second DC voltage and a plurality of predetermined threshold voltages, respectively. The connection switching may be performed based on the duty ratio in the parallel connection state, the duty ratio in the mixed connection state, and the duty ratio in the series connection state according to the magnitude of the first or second DC voltage. Connection switching may be performed so that at least two of them change. In the latter case, since the duty ratio of the connection state changes according to the magnitude of the first or second DC voltage, these values do not change abruptly (changes continuously). In the latter case, the connection switching means continuously increases the turn ratio between the first winding and the second winding as the first DC voltage increases, and the second DC voltage. It is possible to change the duty ratio of the connected state so that the turn ratio continuously decreases as the value increases.

  In the first switching power supply device of the present invention, when the input second DC voltage is voltage-converted to output the first DC voltage, the connection switching means has the first DC voltage set to a predetermined value. Connection switching may be performed so that the target voltage value is obtained. When configured in this manner, the range of the output voltage (first DC voltage) that can be converted from a constant input voltage (second DC voltage) is wider than in the past.

  In this case, the connection switching means includes a plurality of connection switching elements and a second control unit that controls the on / off states of the plurality of connection switching elements according to the magnitude of the target voltage value. It is possible to configure. The connection switching means preferably performs connection switching in the order of parallel connection, mixed connection and series connection as the target voltage value increases. When configured in this manner, the turn ratio between the first winding and the second winding increases as the target voltage value of the output voltage (first DC voltage) increases.

  In the first switching power supply device of the present invention, four first circuits are provided, and the four current paths corresponding to the four first circuits are connected in four parallel connection states, two series and two parallel mixed connection states, and It can be configured to have four serial connection states. In addition, six first circuits are provided, and six current paths corresponding thereto are connected in six parallel connection states, two series and three parallel mixed connection states, and three series and two parallel mixed connections. And 6 series connected states. If the number of first circuits is N (natural number of 4 or more) as in these cases, it is preferable that there are 3 or more divisors of N. In such a configuration, as the divisor number of N increases, the number of connection states that the current paths can take increases.

  In the first switching power supply device of the present invention, each of the four switching elements may always perform an on / off operation regardless of the connection state between the plurality of current paths. Depending on the connection state, an on / off operation state or an on state may be set. In the case of the former configuration, the control for the four switching elements is easier than in the case of the latter configuration.

  In the first switching power supply device of the present invention, a center tap type or push-pull type second circuit may be provided on the second terminal pair side, or a full bridge type second circuit. You may make it provide. In the case of the center tap type second circuit, this circuit functions as a rectifier circuit, while in the case of the push-pull second circuit, this circuit functions as an inverter circuit. In the case of the full bridge type second circuit, this circuit functions as a rectifier circuit or an inverter circuit.

  The second switching power supply device of the present invention includes first and second terminal pairs, and a first DC voltage on the first terminal pair side and a second DC voltage on the second terminal pair side. A plurality of first windings arranged on the first terminal pair side and having the same number of turns, and a second winding arranged on the second terminal pair side. And a plurality of full-bridge circuits each including four switching elements, each of which is provided between the first terminal pair side and the plurality of first windings. Drive circuits that are driven in synchronization with each other, a plurality of inductors provided corresponding to the plurality of circuits, the plurality of circuits, and the first windings respectively corresponding to the plurality of circuits. Multiple current paths connected in parallel or in series It is obtained and a connection switching means for performing connection changeover such that.

  In the second switching power supply device of the present invention, the plurality of circuits operating in synchronization with each other function as an inverter circuit or a rectifier circuit, and the first DC voltage on the first terminal side and the second circuit are transformed by the transformer action of the transformer. Voltage conversion is performed with the second DC voltage on the terminal side. Further, connection switching is performed by the connection switching means so that the plurality of current paths are connected in parallel or in series. Here, since the plurality of first windings of the transformer respectively correspond to the plurality of circuits and have the same number of turns, when the plurality of current paths are connected in series with each other, compared to the case where the plurality of current paths are connected in parallel with each other, The turn ratio between the first winding and the second winding is increased. In addition, since a plurality of inductors are provided corresponding to the plurality of switching circuits, a change in current in the circuit becomes gentle due to the action of maintaining the magnitude of the current by these inductors.

  According to the first switching power supply device of the present invention, a transformer having a plurality of first windings having the same number of turns is provided corresponding to each of the plurality of first circuits, and a plurality of current paths are provided by the connection switching means. Since they are connected in parallel with each other, in series connection, or mixed in series and parallel, the turn ratio between the first winding and the second winding increases in the order of parallel connection, mixed connection, and series connection. Therefore, it is possible to further widen the voltage range that can be converted compared to the conventional case.

  According to the second switching power supply device of the present invention, a transformer having a plurality of first windings having the same number of turns and a plurality of inductors are provided corresponding to a plurality of circuits operating in synchronization with each other, and connected. Since the plurality of current paths are connected in parallel or in series by the switching means, the turn ratio of the primary side winding and the secondary side winding is larger in the case of series connection than in the case of parallel connection. In addition, the current change in the circuit can be moderated. Therefore, the transformer turns ratio can be switched and the tolerance for the timing difference between the circuits can be increased, and the conversion of the voltage range that can be converted can be realized while suppressing the generation of surge current.

  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.

[First Embodiment]
FIG. 1 shows a configuration of a switching power supply apparatus according to the first embodiment of the present invention. This switching power supply device generates a DC low voltage VL based on a DC high voltage VH applied from the high voltage battery 51 between the input / output terminals T1 and T2, and outputs the DC low voltage VL from the input / output terminals T3 and T4. On the other hand, a DC high voltage VH is generated based on the DC low voltage VL applied between the low voltage battery 52 and the input / output terminals T3 and T4, and the forward voltage is supplied to the input / output terminals T1 and T2. This is a bidirectional switching power supply device (DC-DC converter) capable of performing a reverse operation that is output from the power supply and supplied to the high-voltage battery 51.

  This switching power supply includes a smoothing capacitor CH, four switching circuits 11-14, connection changeover switches S51-S53, S61-S63 provided between a high-voltage line L1H and a low-voltage line L1L on the high-voltage battery 51 side (high-voltage side). And four inductors Lr1 to Lr4, a transformer 3 having windings 31A to 31D on the high voltage side and windings 32A and 32B on the low voltage battery 52 side (low voltage side), a switching circuit 4 provided on the low voltage side, and an inductor Lch And smoothing capacitor CL, voltage detection circuit 61 for detecting DC high voltage VH, voltage detection circuit 62 for detecting DC low voltage VL, and operations of switching circuits 11-14 and connection changeover switches S51-S53, S61-S63. And a control unit 7 for controlling each of them.

  The smoothing capacitor CH is for smoothing the DC high voltage VH.

  The switching circuit 11 has four switching elements S11 to S14 and diodes D11 to D14 connected in parallel to the switching elements S11 to S14, respectively, and has a full-bridge circuit configuration. Specifically, one ends of the switching elements S11 and S12 are connected to each other at a connection point P5, and one ends of the switching elements S13 and S14 are connected to each other at a connection point P9. The other ends of the switching elements S11 and S13 are connected to each other at the connection point P3 (P21) via the connection changeover switch S51, and the other ends of the switching elements S12 and S14 are connected via the connection changeover switch S61. They are connected to each other at point P4 (P22), and the other ends are connected to input / output terminals T1 and T2, respectively.

  Similarly, the switching circuit 12 includes four switching elements S21 to S24 and diodes D21 to D24 connected in parallel to the switching elements S21 to S24, respectively. It has become. Specifically, one ends of the switching elements S21 and S22 are connected to each other at the connection point P10, and one ends of the switching elements S23 and S24 are connected to each other at the connection point P11. The other ends of the switching elements S21 and S23 are connected to each other at the connection point P21 (P23) via the connection changeover switches S51 and S52, respectively, and the other ends of the switching elements S22 and S24 are respectively connected to the connection changeover switch S61. , S62 are connected to each other at a connection point P22 (P24), and the other ends are connected to input / output terminals T1 and T2, respectively.

  Similarly, the switching circuit 13 includes four switching elements S31 to S34 and diodes D31 to D34 connected in parallel to the switching elements S31 to S34, respectively. It has become. Specifically, one ends of the switching elements S31 and S32 are connected to each other at the connection point P12, and one ends of the switching elements S33 and S34 are connected to each other at the connection point P13. The other ends of the switching elements S31 and S33 are connected to each other at the connection point P23 (P25) via the connection changeover switches S52 and S53, respectively, and the other ends of the switching elements S32 and S34 are respectively connected to the connection changeover switch S62. , S63 to each other at a connection point P24 (P26), and the other ends are connected to input / output terminals T1 and T2, respectively.

  Similarly, the switching circuit 14 includes four switching elements S41 to S44 and diodes D41 to D44 connected in parallel to the switching elements S41 to S44, respectively. It has become. Specifically, one ends of the switching elements S41 and S42 are connected to each other at a connection point P14, and one ends of the switching elements S43 and S44 are connected to each other at a connection point P8. The other ends of the switching elements S41 and S43 are connected to each other at the connection point P25 (P6) via the connection changeover switch S53, and the other ends of the switching elements S42 and S44 are connected via the connection changeover switch S63. They are connected to each other at a point P26 (P7), and the other ends are connected to the input / output terminals T1 and T2, respectively.

  With such a configuration, the switching circuits 11 to 14, 21 to 24, 31 to 34, and 41 to 44 are provided with drive signals (drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG41). In accordance with SG44), as will be described later, it functions as a full-bridge inverter circuit during forward operation, and functions as a full-bridge rectifier circuit during reverse operation.

  The switching elements S11 to S14, S21 to S24, S31 to S34, and S41 to S44 are, for example, switches such as field effect transistors (MOS-FETs) or IGBTs (insulated gate bipolar transistors). It is composed of elements. When MOS-FETs are used as these switching elements, the diodes D11 to D14, D21 to D24, D31 to D34, and D41 to S44 can each be constituted by a parasitic diode of the MOS-FET. is there. Moreover, when comprised in this way, it becomes unnecessary to provide the diodes D11-D14, D21-D24, D31-D34, D41-D44 separately from a switch element, and can simplify a circuit structure. In addition, when the diodes D11 to D14, D21 to D24, D31 to D34, and D41 to D44 are each composed of a parasitic diode of MOS-FET, they are synchronized with a period in which the parasitic diode of the MOS-FET is conductive. Thus, it is preferable that the MOS-FET itself is also turned on. This is because rectification can be performed with a smaller voltage drop.

  The connection changeover switches S51 to S53 are respectively arranged between the connection points P15 and P21, between the connection points P17 and P23, and between the connection points P19 and P25. Further, the connection changeover switches S61 to S63 are respectively arranged between the connection points P16 and P22, between the connection points P18 and P24, and between the connection points P20 and P26. These connection changeover switches S51 to S53, S61 to S63 are also controlled to be turned on / off by drive signals (drive signals SG51 to SG53, SG61 to SG63) supplied from the control unit 7. As described in detail later, the connection between the current paths in the switching circuits 11 to 14 is switched. The connection changeover switches S51 to S53 and S61 to S63 are also composed of switch elements such as MOS-FETs and IGBTs.

  The inductor Lr1 has one end connected to the connection point P5 and the other end connected to the connection point P9 via the winding 31A of the transformer 3, and is connected to a bridge circuit (switching circuit 11) including the switching elements S11 to S14. H bridge connection. Further, the inductor Lr2 has one end connected to the connection point P11 and the other end connected to the connection point P10 via the winding 31B of the transformer 3, and includes a bridge circuit (switching circuit 12) including the switching elements S21 to S24. ) Is H-bridge connected. The inductor Lr3 has one end connected to the connection point P12 and the other end connected to the connection point P13 via the winding 31C of the transformer 3, and is composed of a bridge circuit (switching circuit 13) composed of switching elements S31 to S34. ) Is H-bridge connected. The inductor Lr4 has one end connected to the connection point P8 and the other end connected to the connection point P14 via the winding 31D of the transformer 3, and is composed of a bridge circuit (switching circuit 14) composed of switching elements S41 to S44. ) Is H-bridge connected.

  The transformer 3 includes four high-voltage side windings 31A to 31D and two low-voltage side windings 32A and 32B, which are provided corresponding to the switching circuits 11 to 14, respectively, and have the same number of turns. Among these, the winding 31A on the high voltage side has one end connected to the other end of the inductor Lr1 and the other end connected to the connection point P9, and is connected to a bridge circuit (switching circuit 11) composed of the switching elements S11 to S14. H bridge connection. Winding 31B has one end connected to connection point P10 and the other end connected to the other end of inductor Lr2, and is H-bridge connected to a bridge circuit (switching circuit 12) composed of switching elements S21 to S24. ing. The winding 31C has one end connected to the other end of the inductor Lr3 and the other end connected to the connection point P13. The winding 31C is H-bridge connected to a bridge circuit (switching circuit 13) including switching elements S31 to S34. ing. The winding 31D has one end connected to the connection point P14 and the other end connected to the other end of the inductor Lr4, and is H-bridge connected to a bridge circuit (switching circuit 14) including switching elements S41 to S44. ing. On the other hand, one ends of the low-voltage side windings 32A and 32B are connected to each other by a center tap CT, and the center tap CT is guided to the input / output terminal T3 via the inductor Lch on the low-voltage side high-voltage line L2H. . With such a configuration, the transformer 3 steps down the input AC voltage generated by the switching circuits 11 to 14 or the switching circuit 4 described later, and from each end of the windings 32A and 32B or the end of the windings 31A to 31D. The output AC voltages are 180 degrees out of phase with each other. In this case, the degree of step-down or step-up is determined by the turn ratio between the windings 31A to 31D and the windings 32A and 32B.

  The switching circuit 4 includes two switching elements S10 and S20 and diodes D10 and D20 connected in parallel to the switching elements S10 and S20, respectively, and has a push-pull circuit configuration. Specifically, the diodes D10 and D20 have a cathode connected to the other end of the winding 32A of the transformer 3 and a cathode of the diode D20 connected to the other end of the winding 32B of the transformer 3. The anodes of the diodes D10 and D20 are connected to each other and connected to a low voltage line L2L on the low voltage side. That is, the diodes D10 and D20 of the switching circuit 4 have a center tap type anode common connection configuration. With such a configuration, as will be described later, the switching circuit 4 functions as a center tap type rectifier circuit during forward operation and functions as a push-pull inverter circuit during reverse operation.

  Note that the switching elements S10 and S20 are also composed of switching elements such as MOS-FETs and IGBTs. Further, when MOS-FETs are used as these switch elements, the diodes D10 and D20 can each be constituted by a parasitic diode of the MOS-FET. Even in such a configuration, it is not necessary to provide the diodes D10 and D20 separately from the switch element, and the circuit configuration can be simplified. In addition, when the diodes D10 and D20 are each composed of a MOS-FET parasitic diode, the MOS-FET itself is also turned on in synchronization with the period in which the MOS-FET parasitic diode is conducted. It is preferable. This is because rectification can be performed with a smaller voltage drop.

  The inductor Lch is inserted into the high voltage line L2H, and one end is connected to the center tap CT and the other end is connected to the input / output terminal T3. The smoothing capacitor CL is provided between the high voltage line L2H (specifically, the other end of the inductor Lch) and the low voltage line L2L, and an input / output terminal T4 is provided at the end of the low voltage line L2L. Yes. With this configuration, the inductor Lch functions as a choke coil during forward operation as will be described later, and forms a smoothing circuit together with the smoothing capacitor CL, thereby smoothing the DC voltage rectified by the switching circuit 4 and reducing the DC low voltage. A voltage VL is generated and supplied to the low voltage battery 52 from the input / output terminals T3 and T4.

  The voltage detection circuit 61 is inserted between the connection point P1 on the high-voltage side high-voltage line L1H and the connection point P2 on the low-voltage line L1L, and is connected to the control unit 7. With this configuration, the voltage detection circuit 61 detects the DC high voltage VH and outputs a voltage corresponding to the magnitude of the DC high voltage VH to the control unit 7. As a specific circuit configuration of the voltage detection circuit 61, for example, the DC high voltage VH is detected by a voltage dividing resistor (not shown) arranged between the connection point P1 and the connection point P2. For example, a device that generates a voltage corresponding to this.

  The voltage detection circuit 62 is inserted between the control unit 7 and a connection point on the high voltage line L2H on the low voltage side (specifically, a connection point between the other end of the inductor Lch and the input / output terminal T3). Has been. With this configuration, the voltage detection circuit 62 detects the DC low voltage VL and outputs a voltage corresponding to the magnitude of the DC low voltage VL to the control unit 7. As a specific circuit configuration of the voltage detection circuit 62, as in the case of the voltage detection circuit 61 described above, for example, a voltage dividing resistor arranged between the connection point on the high voltage line L2H and the ground. (Not shown) Thus, there is one that detects the DC low voltage VL and generates a voltage corresponding to this.

  Here, the control unit 7 will be described in detail with reference to FIGS. 2 and 3. FIG. 2 shows a circuit configuration of the control unit 7, and FIG. 3 shows details of current path connection switching control by the control unit 7.

  As shown in FIG. 2, the control unit 7 includes an oscillation circuit 71, an arithmetic circuit 72, comparators Comp1 and Comp2, a differential amplifier (error amplifier) Amp1, and a reference power supply Ref1 of the comparator Comp1. A reference power supply Ref2 of the dynamic amplifier Amp1 and a resistor R1 are included. The positive input terminal of the comparator Comp1 is connected to the output terminal of the voltage detection circuit 61, the negative input terminal is connected to one end of the reference power source Ref1, and the output terminal is connected to the connection changeover switches S51 to S53, S61 to S63. . The positive input terminal of the differential amplifier Amp1 is connected to one end of the reference power supply Ref2, the negative input terminal is connected to the output terminal of the voltage detection circuit 62, and the output terminal is connected to the negative input terminal of the comparator Comp2. The positive input terminal of the comparator Comp2 is connected to the output terminal of the oscillator 71, and the output terminal is connected to the input terminal of the arithmetic circuit 72. The five output terminals of the arithmetic circuit 72 are connected to the switching circuits 11 to 14, 4 respectively. The resistor R1 is disposed between the negative input terminal and the output terminal of the differential amplifier Amp1, and the other ends of the reference power supplies Ref1 and Ref2 are grounded.

  The comparator Comp1 includes a reference potential V1 from the reference power source Ref1 corresponding to the threshold voltage Vth11 and the threshold voltage Vth12, and a voltage potential corresponding to the DC high voltage VH output from the voltage detection circuit 61. And the drive signals SG51 to SG53 and SG61 to SG63 of the connection changeover switches S51 to S53 and S61 to S63 are respectively output based on the comparison result. Specifically, when DC high voltage VH is higher than threshold voltage Vth11, drive signals SG51, SG53, SG61, and SG63 are at the “L” level, while DC high voltage VH is conversely the threshold voltage. When the voltage is lower than the voltage Vth11, the drive signals SG51, SG53, SG61, and SG63 are at the “H” level. Further, when DC high voltage VH is higher than threshold voltage Vth12, drive signals SG52 and SG62 are at "L" level, and conversely, when DC high voltage VH is lower than threshold voltage Vth12. The drive signals SG52 and SG62 are at “H” level.

  The differential amplifier Amp1 amplifies and outputs the potential difference between the reference potential V2 from the reference power supply Ref2 and the potential of the voltage corresponding to the DC low voltage VL output from the voltage detection circuit 62.

  The comparator Comp2 compares the potential of the pulse voltage PLS1 output from the oscillation circuit 71 with the potential of the output voltage from the differential amplifier Amp1, and based on the comparison result, the switching elements S11 to S14, S21 to S24, The pulse voltage used as the origin of the drive signals SG11-SG14, SG21-SG24, SG31-SG34, SG41-SG44 of S31-S34, S41-S44 is output. Specifically, when the output voltage from the differential amplifier Amp1 is higher than the pulse voltage PLS1, the output is at the “L” level, whereas the output voltage from the differential amplifier Amp1 is lower than the pulse voltage PLS1. In this case, the DC input / output becomes “H” level.

  The arithmetic circuit 72 performs a logical operation on the pulse voltage signal output from the comparator Comp2, and drives the switching elements S11 to S14, S21 to S24, S31 to S34, S41 to S44, S10, and the drive signals SG11 to S20. SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44, SG10, and SG20 are output. The arithmetic circuit 72 also outputs drive signals SG10 and SG20 for the switching elements S10 and S20.

  With this configuration, the control unit 7 has the switching elements S11 to S14 in the switching circuit 11, the switching elements S21 to S24 in the switching circuit 12, the switching elements S31 to S34 in the switching circuit 13, and the switching elements in the switching circuit 14. The operations of S41 to S44 and the switching elements S10 and S20 in the switching circuit 4 are respectively controlled. Specifically, during forward operation, the switching elements S11 to S14, S21 to S24, S31 to S34, and S41 to S44 are turned on / off by drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44. The DC low voltage VL is stabilized (maintained constant). More specifically, when the DC low voltage VL detected by the voltage detection circuit 62 increases, the duty ratios of the drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44 output from the control unit 7 are increased. If the detected DC low voltage VL decreases, the duty ratio of the drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44 increases, and the DC low voltage VL is kept constant. It is like that. The control unit 7 switches in synchronization with the conduction periods of the diodes D11 to D14, D21 to D24, D31 to D34, D41 to D44 in the switching circuits 11 to 14 and the diodes D10 and D20 in the switching circuit 4, respectively. When the elements S11 to S14, S21 to S24, S31 to S34, S41 to S44 and the switching elements S10 and S20 are controlled to be turned on (synchronous rectification), these D11 to D14, D21 to D24, D31 to Power loss at D34, D41 to D44, D10, and D20 can be reduced.

  Further, during forward operation, the control unit 7 drives the drive signals SG51 to SG53, SG61 to SG63 according to the magnitude of the voltage (the magnitude of the input voltage) according to the DC high voltage VH output from the voltage detection circuit 61. To control the operations of the connection changeover switches S51 to S53 and S61 to S63, respectively, and a current path (first current path) passing through the switching circuit 11 and the winding 31A, and a current passing through the switching circuit 12 and the winding 31B. A path (second current path), a current path (third current path) passing through the switching circuit 13 and the winding 31C, and a current path (fourth current path) passing through the switching circuit 14 and the winding 31D. In the reverse operation, the target voltage value is increased so that the DC high voltage VH, which is the output voltage, becomes a predetermined target voltage value. Depending on, and performs switching of the same connection state as during forward operation.

  Specifically, as shown in FIG. 3, first, the DC high voltage VH detected by the voltage detection circuit 61 during the forward operation (the target voltage value of the DC high voltage VH during the reverse operation) is predetermined. When it is lower than the threshold voltage Vth11 (predetermined threshold voltage Vth21 during reverse operation), the control unit 7 causes the connection changeover switches S51 to S53 and S61 to S63 to be turned on. Control. Then, the first to fourth current paths are connected in parallel to each other (four parallel connection states). Further, the detected DC high voltage VH (the target voltage value of the DC high voltage VH during reverse operation) is equal to or higher than the threshold voltage Vth11 (threshold voltage Vth21 during reverse operation) and a predetermined threshold voltage Vth12. If it is less than the predetermined threshold voltage Vth22 during reverse operation, the control unit 7 controls the connection changeover switches S51, S61, S53, and S63 to be turned off. Then, the first current path, the second current path, the third current path, and the fourth current path are respectively connected in series, and these series connections are connected in parallel to each other. That is, these first to fourth current paths are in a mixed connection state (two series and two parallel connection states) in series and parallel to each other. Further, when the detected DC high voltage VH (target voltage value of DC high voltage VH during reverse operation) is equal to or higher than threshold voltage Vth12 (threshold voltage Vth22 during reverse operation), control unit 7 Controls the connection changeover switches S51 to S53 and S61 to S63 so that they are all turned off. Then, the first to fourth current paths are in series connection with each other (four series connection states). Here, the turns ratio (np / ns) between the number of turns np of the windings 31A to 31D and the number of turns ns of the windings 32A and 32B in the transformer 3 is 4 parallel connection state, 2 series 2 parallel state, and 4 series connection state. In comparison, the four series connection state (turn ratio = 4n) is four times as large as the four parallel connection state (turn ratio = n), and the four series connection state (turn ratio = 2n) is four parallel. It is twice as large as the connected state. Details of the connection switching control by the control unit 7 will be described later.

  Here, the switching elements S11 to S14, the switching elements S21 to S24, the switching elements S31 to S34, and the switching elements S41 to S44 each correspond to a specific example of “four switching elements” in the present invention, and the switching circuits 11 to 14 corresponds to a specific example of “a plurality of first circuits” and “a plurality of circuits” in the present invention. The windings 31A to 31D correspond to a specific example of “first winding” in the present invention, and the windings 32A and 32B correspond to a specific example of “second winding” in the present invention. The control unit 7 corresponds to a specific example of “driving circuit”, “first control unit”, and “second control unit” in the present invention. Further, the inductors Lr1 to Lr4 correspond to a specific example of “a plurality of inductors” in the present invention. The connection change-over switches S51 to S53 and S61 to S63 correspond to a specific example of “a plurality of connection change-over elements” in the present invention. The controller 7 corresponds to a specific example of “connection switching means” in the present invention. The input / output terminals T1 and T2 correspond to a specific example of “first terminal pair” in the present invention, and the input / output terminals T3 and T4 correspond to a specific example of “second terminal pair” in the present invention. To do. Further, the DC high voltage VH corresponds to a specific example of “first DC voltage” in the present invention, and the DC low voltage VL corresponds to a specific example of “second DC voltage” in the present invention.

  Next, the operation of the switching power supply device configured as described above will be described. First, the basic operation of the switching power supply device will be described by dividing it into forward operation and reverse operation.

  First, during forward operation (step-down operation from the DC high voltage VH to the DC low voltage VL), the switching elements S11 to S14, S21 to S24, S31 to S34, and S41 to S44 in the switching circuits 11 to 14 are respectively controlled. On / off operation is performed by the drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44 from the unit 7 and functions as an inverter circuit, while the switching elements S10 and S20 in the switching circuit 4 are driven by the drive signal SG10. SG20 are turned off and function as a rectifier circuit. Further, the inductor Lch functions as a choke coil. In the case of the synchronous rectification described above, the switching elements S10 and S20 are also turned on / off.

  Therefore, during this forward operation, the following basic operation is performed. First, a DC high voltage VH is applied from the high voltage battery 51 between the input / output terminals T1 and T2, and an input AC voltage is generated by the switching circuits 11 to 14 functioning as an inverter circuit.

  Next, when this input AC voltage is input to the windings 31A to 31D of the transformer 3, it is transformed (in this case, stepped down), and the output AC voltage is output from the windings 32A and 32B. The output AC voltage is rectified by the diodes D10 and D20 in the switching circuit 4 functioning as a rectifier circuit, and smoothed by the inductor Lch and the smoothing capacitor CL functioning as a choke coil, whereby the input / output terminals T3 and T3 are output. The voltage is output as a DC low voltage VL from T4 and supplied to the low voltage battery 52.

  On the other hand, at the time of reverse operation (step-up operation from the DC low voltage VL to the DC high voltage VH), the switching elements S11 to S14, S21 to S24, S31 to S34, and S41 to S44 in the switching circuits 11 to 14 are The drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44 are turned off and function as a rectifier circuit, while the switching elements S10 and S20 in the switching circuit 4 are turned on and off by the drive signals SG10 and SG20. Operates and functions as an inverter circuit. The inductor Lch functions as a boosting inductor. In the case of the synchronous rectification described above, the switching elements S11 to S14, S21 to S24, S31 to S34, and S41 to S44 are also turned on / off.

  Therefore, the basic operation is as follows during this backward operation. First, a DC low voltage VL is applied from the low voltage battery 52 to the input / output terminals T3 and T4, and an input AC voltage is generated by the inductor Lch functioning as a boosting inductor and the switching circuit 4 functioning as an inverter circuit.

  Next, when the input AC voltage is input to the windings 32A and 32B of the transformer 3, respectively, the voltage is transformed (in this case, boosted), and the output AC voltage is output from the windings 31A to 31D. The output AC voltage is rectified by the diodes D11 to D14, D21 to D24, D31 to D34, and D41 to D44 in the switching circuits 11 to 14 functioning as a rectifier circuit, and the DC high voltage VH from the input / output terminals T1 and T2. And is fed to the high voltage battery 51.

  In this way, the forward operation and the backward operation are performed in the switching power supply device of the present embodiment.

  Next, with reference to FIGS. 3 to 20, the current path connection switching operation, which is the main feature of the present invention, will be described in detail by dividing it into a forward operation and a backward operation.

<Connection switching operation during forward operation>
First, the connection switching operation of the current path during the forward operation will be described with reference to FIGS.

  4 to 9 each show an operation state in the forward direction in the switching power supply device of the present embodiment. 4 and 5 show the case where the above-mentioned first to fourth current paths are in a 4-parallel connection state, and FIGS. 6 and 7 show the case where they are in a 2-series 2-parallel connection state. 8 and FIG. 9 respectively show the case where these are in a four-series connection state. FIG. 10 shows the DC high voltage VH and the duty ratio (drive signals SG11 to SG14, SG21 to SG24, drive in forward operation) in these 4 parallel connection state, 2 series 2 parallel connection state, and 4 series connection state. This shows the relationship with the signals SG31 to SG34, SG41 to SG44).

  First, the 4 parallel connection state shown in FIGS. 4 and 5 is a case where the DC high voltage VH detected by the voltage detection circuit 61 is lower than the threshold voltage Vth11 as shown in FIG. 10, for example. In this case, the connection selector switches S51 to S53 and S61 to 63 are set to be in an ON state by the control unit 7 (see FIG. 3), and the switching circuits 11 to 14 perform parallel operations independent of each other.

  Specifically, in the operation state shown in FIG. 4, the current path Ip11 (corresponding to the first current path) passing through the smoothing capacitor CH, the switching element S11, the inductor Lr1, the winding 31A, the switching element S14, and the connection changeover switch S61. ), A smoothing capacitor CH, a connection switch S51, a switching element S21, a winding 31B, an inductor Lr2, a switching element S24, and a current switching path S62 and a connection switching switch S62, and a smoothing capacitor CH , A connection switch S52, a switching element S31, an inductor Lr3, a winding 31C, a switching element S34, and a current path Ip13 (corresponding to the third current path) passing through the connection switch S63, a smoothing capacitor CH, a connection switch S53, Switching element S41, winding 31D, inductor Lr4 and a current path Ip14 through the switching element S44 (corresponding to the fourth current path), but the respective parallel connection state.

  Further, in the operation state shown in FIG. 5, the current path Ip21 (corresponding to the first current path) passing through the smoothing capacitor CH, the connection changeover switch S51, the switching element S13, the winding 31A, the inductor Lr1, and the switching element S12; Smoothing capacitor CH, connection switching switch S52, switching element S23, inductor Lr2, winding 31B, current path Ip22 (corresponding to the second current path) passing through switching element S22 and connection switching switch S61, smoothing capacitor CH, connection switching A current path Ip23 (corresponding to the third current path) passing through the switch S53, the switching element S33, the winding 31C, the inductor Lr3, the switching element S32 and the connection changeover switch S62, the smoothing capacitor CH, the switching element S43, the inductor Lr4, the winding 31D, a current path Ip24 through the switching element S42, and connection changeover switch S63 (corresponding to the fourth current path), but the respective parallel connection state.

  Here, the four high-voltage side windings 31A to 31D in the transformer 3 correspond to the four switching circuits 11 to 14, respectively, and have the same number of turns. Therefore, the high-voltage side winding 31A in this four-parallel connection state. The winding ratio between the winding number np of .about.31D and the winding number ns of the low-voltage side windings 32A and 32B is (np / ns) (= n) as it is (see FIG. 3).

  Further, the two series two parallel connection states shown in FIGS. 6 and 7 are, for example, as shown in FIG. 10, when the DC high voltage VH detected by the voltage detection circuit 61 is equal to or higher than the threshold voltage Vth11. This is the case when the voltage is lower than Vth12. In this case, the control unit 7 sets the connection change-over switches S51, S61, S53, and S63 to be turned off, while setting the connection change-over switches S52 and S62 to be turned on (FIG. 3). The switching circuits 11 and 12 and the switching circuits 13 and 14 perform independent parallel operations.

  Specifically, in the operation state shown in FIG. 6, the current path (corresponding to the first current path) passing through the smoothing capacitor CH, the switching element S11, the inductor Lr1, and the winding 31A, the winding 31B, the inductor Lr2, A current path passing through the switching element S24 and the connection changeover switch S62 (corresponding to the second current path) is coupled by a current path passing through the diode D13 and the switching element S21 and a current path passing through the switching element S14 and the diode D22. They are connected in series with each other. Further, a current path (corresponding to the third current path) passing through the smoothing capacitor CH, the connection changeover switch S52, the switching element S31, the inductor Lr3, and the winding 31C, and a current path passing through the winding 31D, the inductor Lr4, and the switching element S44. (Corresponding to the fourth current path) are coupled by a current path passing through the diode D33 and the switching element S41 and a current path passing through the switching element S34 and the diode D42, and are connected in series. That is, it passes through the smoothing capacitor CH, switching element S11, inductor Lr1, winding 31A, switching element S14 and diode D22 (or diode D13 and switching element S21), winding 31B, inductor Lr2, switching element S24 and connection changeover switch S62. Current path Isp11, smoothing capacitor CH, connection changeover switch S52, switching element S31, inductor Lr3, winding 31C, switching element S34 and diode D42 (or diode D33 and switching element S41), winding 31D, inductor Lr4 and switching element A current path Isp12 passing through S44 is formed.

  In the operation state shown in FIG. 7, the current path (corresponding to the second current path) passing through the smoothing capacitor CH, the connection changeover switch S52, the switching element S23, the inductor Lr2, and the winding 31B, the winding 31A, the inductor A current path through Lr1 and switching element S12 (corresponding to the first current path) is coupled by a current path through diode D21 and switching element S13 and a current path through switching element S22 and diode D14, and connected in series with each other. It becomes a state. Further, a current path (corresponding to the fourth current path) passing through the smoothing capacitor CH, the switching element S43, the inductor Lr4 and the winding 31D, and a current path passing through the winding 31C, the inductor Lr3, the switching element S32 and the connection changeover switch S62. (Corresponding to the third current path) are coupled by a current path passing through the diode D41 and the switching element S33 and a current path passing through the switching element S42 and the diode D34, and are connected in series. That is, it passes through the smoothing capacitor CH, the connection changeover switch S52, the switching element S23, the inductor Lr2, the winding 31B, the switching element S22 and the diode D14 (or the diode D21 and the switching element S13), the winding 31A, the inductor Lr1 and the switching element S12. Current path Isp21, smoothing capacitor CH, switching element S43, inductor Lr4, winding 31D, switching element S42 and diode D34 (or diode D41 and switching element S33), winding 31C, inductor Lr3, switching element S32 and connection changeover switch A current path Isp22 passing through S62 is formed.

  Here, as described above, the windings 31A to 31D of the transformer 3 correspond to the four switching circuits 11 to 14, respectively, and have the same number of turns. The turn ratio between the turn number np of 31D and the turn number ns of the low-voltage side windings 32A and 32B is 2 × (np / ns) = 2n (see FIG. 3). That is, the turn ratio in the 2-series 2-parallel connection state is twice as large as that in the 4-parallel connection state (turn ratio = n).

  Further, the four series connection states shown in FIGS. 8 and 9 are cases where the DC high voltage VH detected by the voltage detection circuit 61 is equal to or higher than the threshold voltage Vth12 as shown in FIG. 10, for example. In this case, the connection changeover switches S51 to S53 and S61 to S63 are set by the control unit 7 so as to be turned off (see FIG. 3), and the switching circuits 11 to 14 are connected in series with each other.

  Specifically, in the operation state shown in FIG. 8, the current path (corresponding to the first current path) passing through the smoothing capacitor CH, the switching element S11, the inductor Lr1, and the winding 31A, the winding 31B and the inductor Lr2 are connected. A current path through (corresponding to the second current path), a current path through the inductor Lr3 and the winding 31C (corresponding to the third current path), and a current path through the winding 31D, the inductor Lr4 and the switching element S44 ( Corresponds to the fourth current path), the current path through the diode D13 and the switching element S21, the current path through the switching element S14 and the diode D22, the current path through the diode D23 and the switching element S31, and the switching element S24. Current path through diode D32 and diode D3 And a current path through the switching element S41, are coupled by a current path through the switching element S34 and the diode D42, the series connection state to each other. That is, smoothing capacitor CH, switching element S11, inductor Lr1, winding 31A, switching element S14 and diode D22 (or diode D13 and switching element S21), winding 31B, inductor Lr2, switching element S24 and diode D32 (or diode D23) And the switching element S31), the inductor Lr3, the winding 31C, the switching element S34 and the diode D42 (or the diode D33 and the switching element S41), the winding 31D, the inductor Lr4, and the current path Is1 passing through the switching element S44.

  In the operation state shown in FIG. 9, the current path passing through the smoothing capacitor CH, the switching element S43, the inductor Lr4, and the winding 31D (corresponding to the fourth current path), and the current path passing through the winding 31C and the inductor Lr3. (Corresponding to the third current path), the current path passing through the inductor Lr2 and the winding 31B (corresponding to the second current path), and the current path passing through the winding 31A, the inductor Lr1 and the switching element S12 (first Corresponds to the current path), the current path through the diode D41 and the switching element S33, the current path through the switching element S42 and the diode D34, the current path through the diode D31 and the switching element S23, and the switching element S32 and the diode D24. Current path through the diode D21 and A current path through the switching element S13, are coupled by a current path through the switching element S22 and the diode D14, the series connection state to each other. That is, smoothing capacitor CH, switching element S43, inductor Lr4, winding 31D, switching element S42 and diode D34 (or diode D41 and switching element S33), winding 31C, inductor Lr3, switching element S32 and diode D24 (or diode D31) And the switching element S23), the inductor Lr2, the winding 31B, the switching element S22 and the diode D14 (or the diode D21 and the switching element S13), the winding 31A, the current path Is2 passing through the inductor Lr1 and the switching element S12.

  Here, as described above, the windings 31A to 31D of the transformer 3 respectively correspond to the four switching circuits 11 to 14 and have the same number of turns. Therefore, the windings 31A to 31D on the high-voltage side in this four-series connection state. The turn ratio between the number of turns np and the number of turns ns of the low-voltage side windings 32A and 32B is 4 × (np / ns) = 4n (see FIG. 3). That is, the turn ratio in the 4-series connection state is four times as large as that in the 4-parallel connection state (turn ratio = n).

  Thus, for example, as shown in the graph G1 of FIG. 10, the input voltage is higher in the 2-series 2-parallel connection state than in the 4-parallel connection state, and in the 4-series connection state rather than the 2-series 2-parallel connection state. When the DC high voltage VH is high, the on-duty ratio of the drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44 can be maintained high, and such connection switching control is performed. This widens the range of the input voltage (DC high voltage VH) that can maintain a constant output voltage (DC low voltage VL) (from the input voltage range VH11 from voltage Vmin1 to voltage Vmax11, from voltage Vmin1 to voltage Vmax12). To the input voltage range VH12).

  Next, referring to FIGS. 11 to 13, in the switching power supply device of the present embodiment and the conventional switching power supply device (comparative example), comparison is made regarding whether or not surge current is generated in the circuit during forward operation. explain.

  Here, FIG. 11 illustrates a configuration of a switching power supply device according to a comparative example. Specifically, the inductors Lr1 to Lr4 are removed from the switching power supply device of the present embodiment shown in FIG. 12 and 13 show timing waveforms of currents flowing through the primary windings 31A to 31D of the transformer 3 in the comparative example and the switching power supply according to the present embodiment, respectively. Is the drive signals SG51 to SG53, SG61 to SG63 of the connection changeover switches S51 to S53, S61 to S63, (B) is the currents I31A and I31C flowing through the high-voltage side windings 31A and 31C, and (C) is the high-voltage side. Currents I31B and I31D flowing through the windings 31B and 31D are respectively shown. For the currents I31A to I31D, the direction of the arrow shown in FIG. 11 is the positive direction.

  First, in the comparative example shown in FIG. 12, when the drive signals SG51 to SG53, SG61 to SG63 are at "H" level, that is, the connection changeover switches S51 to S53, S61 to S63 are turned on, respectively, and the four parallel connection states In this case (state before timing t101), it can be seen that surge waveforms as indicated by reference numerals G11 to G13 and G21 to G23 are generated in the current waveforms of the currents I31A to I31D. This surge current waveform is caused by a shift in timing between the drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44, that is, a shift in operation timing between the switching circuits 101 to 104 operating in synchronization with each other. is there. If these timings are completely synchronized, a surge waveform will not occur, but in practice it is difficult because of the parasitic resistance and parasitic capacitance of the wiring. In this comparative example, since the inductors Lr1 to Lr4 are not provided as described above, the tolerance for such a shift in the operation timing is small, and such a surge current is generated even by a slight shift. It has been.

  In contrast, in the present embodiment shown in FIG. 13, no surge waveform is generated in the current waveforms of the currents I31A to I31D even in the case of the four parallel connection state before the timing t1. This is because the switching power supply according to the present embodiment is provided with the four inductors Lr1 to Lr4 corresponding to the two switching circuits 11 to 14 as described above. This is because the change in the current in the circuit becomes gentle due to the action of maintaining the above, and as a result, the tolerance for the deviation of the operation timing increases. Thus, in the present embodiment in which the inductors Lr1 to Lr4 are provided, tolerance for timing deviation between the switching circuits 11 to 14 that operate in parallel with each other is compared with the comparative example (conventional) in which the inductors Lr1 to Lr4 are not provided. The degree is increased and the generation of surge current is avoided.

<Connection switching operation during reverse operation>
Next, with reference to FIG. 14 to FIG. 20, the connection switching operation of the current path during the backward operation will be described.

  FIG. 14 to FIG. 19 each show the operation state in the reverse direction in the switching power supply device of the present embodiment. 14 and 15 show the case where the first to fourth current paths described above are in a 4-parallel connection state, and FIGS. 16 and 17 show the case where they are in a 2-series 2-parallel connection state. FIG. 18 and FIG. 19 respectively show the case where these are in a 4-series connection state. Further, FIG. 20 shows the DC high voltage VH and the duty ratio (drive signals SG11 to SG14, SG21 to SG24, drive in reverse operation) in these 4 parallel connection state, 2 series 2 parallel connection state, and 4 series connection state. This shows the relationship with the signals SG31 to SG34, SG41 to SG44).

  First, the four parallel connection states shown in FIGS. 14 and 15 are cases where the target voltage value of the DC high voltage VH is lower than the threshold voltage Vth21, for example, as shown in FIG. In this case, the connection selector switches S51 to S53 and S61 to 63 are set to be in the ON state by the control unit 7, and the switching circuits 11 to 14 perform independent parallel operations.

  Specifically, in the operation state shown in FIG. 14, the current path Ip31 (corresponding to the first current path) passing through the smoothing capacitor CH, the diode D12, the inductor Lr1, the winding 31A, the diode D13, and the connection changeover switch S51, , Smoothing capacitor CH, connection changeover switch S61, diode D22, winding 31B, inductor Lr2, diode D23 and connection changeover switch S52, current path Ip32 (corresponding to the second current path), smoothing capacitor CH, connection changeover switch S62, diode D32, inductor Lr3, winding 31C, diode D33, current path Ip33 (corresponding to the third current path) passing through connection switch S53, smoothing capacitor CH, connection switch S63, diode D42, winding 31D , Inductor Lr4 A current path Ip34 through fine diode D43 (corresponding to the fourth current path), but the respective parallel connection state.

  In the operating state shown in FIG. 15, the smoothing capacitor CH, the connection changeover switch S61, the diode D14, the winding 31A, the inductor Lr1 and the diode D11, the current path Ip41 (corresponding to the first current path), the smoothing capacitor CH, connection switch S62, diode D24, inductor Lr2, winding 31B, diode D21 and current path Ip42 (corresponding to the second current path) passing through connection switch S51, smoothing capacitor CH, connection switch S63, diode D34, winding 31C, inductor Lr3, diode D31, and current path Ip43 (corresponding to the third current path) passing through connection switch S52, smoothing capacitor CH, diode D44, inductor Lr4, winding 31D, diode D41 and connection Switching A current path Ip44 through the switch S53 (corresponding to the fourth current path), but the respective parallel connection state.

  Here, similarly to the forward operation, the windings 31A to 31D of the transformer 3 correspond to the four switching circuits 11 to 14, respectively, and have the same number of turns. The turn ratio between the number of turns np of 31A to 31D and the number of turns ns of the low-voltage side windings 32A and 32B is directly (np / ns) (= n).

  In addition, in the two-series two-parallel connection state shown in FIG. 16 and FIG. 17, for example, as shown in FIG. This is the case. In this case, the control unit 7 sets the connection change-over switches S51, S61, S53, and S63 to be turned off, while the connection change-over switches S52 and S62 are set to be turned on, respectively. 11 and 12 and switching circuits 13 and 14 perform parallel operations independent of each other.

  Specifically, in the operating state shown in FIG. 16, the current path (corresponding to the first current path) passing through the smoothing capacitor CH, the diode D12, the inductor Lr1, and the winding 31A, the winding 31B, the inductor Lr2, and the diode A current path passing through D23 and the connection selector switch S52 (corresponding to the second current path) is coupled by a current path passing through the diode D13 and the switching element S21 and a current path passing through the switching element S14 and the diode D22, and is connected in series with each other. Connected. In addition, a current path (corresponding to the third current path) passing through the smoothing capacitor CH, the connection changeover switch S62, the diode D32, the inductor Lr3, and the winding 31C, and a current path (first step) passing through the winding 31D, the inductor Lr4, and the diode D43. Are coupled by a current path passing through the diode D33 and the switching element S41 and a current path passing through the switching element S34 and the diode D42, and are connected in series with each other. That is, the current path through the smoothing capacitor CH, the diode D12, the inductor Lr1, the winding 31A, the switching element S14 and the diode D22 (or the diode D13 and the switching element S21), the winding 31B, the inductor Lr2, the diode D23, and the connection changeover switch S52. Current through Isp31, smoothing capacitor CH, connection changeover switch S62, diode D32, inductor Lr3, winding 31C, switching element S34 and diode D42 (or diode D33 and switching element S41), winding 31D, inductor Lr4 and diode D43 A path Isp32 is formed.

  In the operating state shown in FIG. 17, the current path (corresponding to the second current path) passing through the smoothing capacitor CH, the connection changeover switch S62, the diode D24, the inductor Lr2, and the winding 31B, the winding 31A, and the inductor Lr1 And a current path through the diode D11 (corresponding to the first current path) is coupled by a current path through the diode D21 and the switching element S13 and a current path through the switching element S22 and the diode D14, and is connected in series with each other. Become. In addition, a current path (corresponding to the fourth current path) passing through the smoothing capacitor CH, the diode D44, the inductor Lr4, and the winding 31D, and a current path (first step) passing through the winding 31C, the inductor Lr3, the diode D31, and the connection changeover switch S52. Are coupled by a current path passing through the diode D41 and the switching element S33 and a current path passing through the switching element S42 and the diode D34, and are connected in series with each other. That is, a current path passing through the smoothing capacitor CH, the connection changeover switch S62, the diode D24, the inductor Lr2, the winding 31B, the switching element S22 and the diode D14 (or the diode D21 and the switching element S13), the winding 31A, the inductor Lr1 and the diode D11. Current through Isp41, smoothing capacitor CH, diode D44, inductor Lr4, winding 31D, switching element S42 and diode D34 (or diode D41 and switching element S33), winding 31C, inductor Lr3, diode D31 and connection changeover switch S52 A path Isp42 is formed.

  Here, as in the forward operation, the windings 31A to 31D of the transformer 3 correspond to the four switching circuits 11 to 14 and have the same number of turns. The turn ratio between the number of turns np of the windings 31A to 31D and the number of turns ns of the low-voltage side windings 32A and 32B is 2 × (np / ns) = 2n. That is, the turn ratio in the 2-series 2-parallel connection state is twice as large as that in the 4-parallel connection state (turn ratio = n).

  Further, the four series connection states shown in FIGS. 18 and 19 are cases where the target voltage value of the DC high voltage VH is equal to or higher than the threshold voltage Vth22 as shown in FIG. 20, for example. In this case, the connection selector switches S51 to S53 and S61 to S63 are set by the control unit 7 to be turned off, and the switching circuits 11 to 14 are connected in series to perform a series operation.

  Specifically, in the operating state shown in FIG. 18, the current path (corresponding to the first current path) passing through the smoothing capacitor CH, the diode D12, the inductor Lr1, and the winding 31A, and the winding 31B and the inductor Lr2 are passed. A current path (corresponding to the second current path), a current path passing through the inductor Lr3 and the winding 31C (corresponding to the third current path), a current path passing through the winding 31D, the inductor Lr4 and the diode D43 (fourth) Current path through the diode D13 and the switching element S21, a current path through the switching element S14 and the diode D22, a current path through the diode D23 and the switching element S31, and the switching element S24 and the diode. Current path through D32, diode D33 and A current path through the switching element S41, are coupled by a current path through the switching element S34 and the diode D42, the series connection state to each other. That is, smoothing capacitor CH, diode D12, inductor Lr1, winding 31A, switching element S14 and diode D22 (or diode D13 and switching element S21), winding 31B, inductor Lr2, switching element S24 and diode D32 (or diode D23 and A current path Is3 passing through the switching element S31), the inductor Lr3, the winding 31C, the switching element S34 and the diode D42 (or the diode D33 and the switching element S41), the winding 31D, the inductor Lr4, and the diode D43 is formed.

  In the operating state shown in FIG. 19, a current path (corresponding to the fourth current path) passing through the smoothing capacitor CH, the diode D44, the inductor Lr4 and the winding 31D, and a current path (corresponding to the fourth current path) ( Corresponding to the third current path), a current path passing through the inductor Lr2 and the winding 31B (corresponding to the second current path), and a current path passing through the winding 31A, the inductor Lr1 and the diode D11 (first current path). Corresponds to the current path through the diode D41 and the switching element S33, the current path through the switching element S42 and the diode D34, the current path through the diode D31 and the switching element S23, and the switching element S32 and the diode D24. Current path, diode D21 and switch A current path through the grayed elements S13, are coupled by a current path through the switching element S22 and the diode D14, the series connection state to each other. That is, smoothing capacitor CH, diode D44, inductor Lr4, winding 31D, switching element S42 and diode D34 (or diode D41 and switching element S33), winding 31C, inductor Lr3, switching element S32 and diode D24 (or diode D31 and A current path Is4 is formed through the switching element S23), the inductor Lr2, the winding 31B, the switching element S22 and the diode D14 (or the diode D21 and the switching element S13), the winding 31A, the inductor Lr1, and the diode D11.

  Here, as in the forward operation, the windings 31A to 31D of the transformer 3 correspond to the four switching circuits 11 to 14, respectively, and have the same number of turns. The turn ratio between the turn number np of 31A to 31D and the turn number ns of the low-voltage side windings 32A and 32B is 4 × (np / ns) = 4n. That is, the turn ratio in the 4-series connection state is four times as large as that in the 4-parallel connection state (turn ratio = n).

  In this way, for example, as shown in the graph G2 of FIG. 20, even in the reverse operation, the 2-series 2-parallel connection state is more than the 4-parallel connection state, and the 4-series connection is more than the 2-series 2-parallel connection state. In the state, the on-duty ratio of the drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44 can be kept low even when the DC high voltage VH that is the output voltage is set higher. By performing such connection switching control, the range of the output voltage (DC high voltage VH) that can be generated from a constant input voltage (DC low voltage VL) is widened (from the output voltage range VH21 from voltage Vmin2 to voltage Vmax21). The output voltage range VH22 from the voltage Vmin2 to the voltage Vmax22 is widened).

  As described above, in the present embodiment, the transformer 3 and the four inductors Lr1 having the four high-voltage side windings 31A to 31D having the same number of turns in correspondence with the four switching circuits 11 to 14 that operate in synchronization with each other. To Lr4, and by the voltage detection circuit 61, the control unit 7 and the connection changeover switches S51 to S53, S61 to S63, the input voltage (DC high voltage VH) is generated during forward operation, and the output voltage (DC high voltage) is operated during reverse operation. According to the target voltage value of VH), the four current paths are connected to each other in four parallel connections, four series connections, or a mixed connection in series and parallel (two series two parallel connections). And the winding ratios of the windings 32A and 32B can be increased in the order of 4 parallel connection, 2 series 2 parallel connection, and 4 series connection. Compared only switchable conventional with the connection, it is possible to widen the conversion voltage range (input voltage range at the time of forward operation, and the output voltage range in reverse operation).

  Moreover, the current change in the circuit can be moderated by the action of the inductors Lr1 to Lr4. Therefore, it is possible to increase the tolerance for the timing difference between the switching circuits 11 to 14, and it is possible to realize the widening of the convertible voltage range while suppressing the generation of the surge current.

  Further, by suppressing the generation of surge current, it is possible to reduce the loss in each element in the circuit and improve the efficiency of the apparatus. Further, by reducing the loss, it is possible to suppress heat generation in the element. Further, by suppressing the generation of the surge current, it is possible to use an element with a low withstand voltage, thereby reducing the component cost and reducing the size of the entire apparatus.

  Furthermore, since the switching elements S11 to S14, S21 to S24, S31 to S34, and S41 to S44 always perform the switching operation (on / off operation) regardless of the connection state, for example, as shown in FIGS. Compared with the case (corresponding to the 4 series connection state during forward operation) and the case shown in FIGS. 23 and 24 (corresponding to the 2 series 2 parallel connection state during forward operation), the switching element S11 by the control unit 7 Control of S14 and S21 to S24 can be further simplified. In other words, it is not necessary to switch the operation of these switching elements between a state in which the switching element is always turned on / off according to the connection state and an operation state in which the switching element is always on or off, and the connection changeover switches S51 to S53, Only by the control of S61 to S63, connection switching between the parallel connection state and the series connection state can be performed.

  In the present embodiment, in each of the switching elements S11 to S14 and S21 to S24 in the switching circuits 1 and 2, between the switching elements S11 and S14 or between the switching elements S12 and S13, and between the switching elements S21 and S24 or switching Although the case where the on / off operation is performed in synchronization with each other between the elements S22 and S23 has been described, these switching elements may perform a phase shift operation (phase difference φ, dead time Td). In such a configuration, the inductors Lr1 and Lr2 and the capacitors C11 to C14 and C21 to C24 constitute an LC resonance circuit and perform a resonance operation. Therefore, the switching elements S11 to S14 and S21 to S24 each perform so-called ZVS (Zero Volt Switching) operation, and in addition to the effects of the present embodiment, the short circuit loss in these switching elements is suppressed. Thus, the efficiency of the apparatus can be further improved.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the switching power supply device of the first embodiment, the four switching circuits 11 to 14, the four high-voltage side windings 31A to 31D and the four inductors Lr1 to Lr4 in the transformer 3 respectively corresponding thereto, Three connection changeover switches S51 to S53 and S61 to S63 are provided, but the switching power supply according to the present embodiment includes six switching circuits 11 to 16 and 6 in the transformer 3 corresponding to each of them. This includes three high-voltage side windings 31A to 31F, six inductors Lr1 to Lr6, and five connection selector switches S51 to S55 and S61 to S65, respectively. Other configurations are the same as those shown in FIG.

  FIG. 25 shows the details of the current path connection switching control by the control unit 7 in the present embodiment. In this figure, the same components as those shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  In the connection switching control according to the present embodiment, first, the DC high voltage VH detected by the voltage detection circuit 61 during forward operation (the target voltage value of the DC high voltage VH during reverse operation) is a predetermined threshold voltage. When the voltage is lower than Vth31 (predetermined threshold voltage Vth41 during reverse operation), the connection changeover switches S51 to S55 and S61 to S65 are turned on by the control unit 7, respectively. Then, six current paths (first to sixth current paths) respectively corresponding to the six switching circuits 11 to 16 and the six high-voltage side windings 31A to 31F are connected in parallel with each other (six parallel connection states). Become.

  The detected DC high voltage VH (the target voltage value of the DC high voltage VH during reverse operation) is equal to or higher than the threshold voltage Vth31 (threshold voltage Vth41 during reverse operation) and a predetermined threshold voltage Vth32 If it is less than the predetermined threshold voltage Vth42 during reverse operation, the control switch 7 turns off the connection selector switches S51, S61, S53, S63, S55, and S65, respectively. The changeover switches S52, S62, S54, and S64 are turned on. Then, the first current path and the second current path, the third current path and the fourth current path, and the fifth current path and the sixth current path are respectively connected in series. Are connected in parallel with each other. That is, these first to sixth current paths are in a mixed connection state (two series and three parallel connection states) in series and parallel to each other.

  The detected DC high voltage VH (the target voltage value of the DC high voltage VH during reverse operation) is equal to or higher than the threshold voltage Vth32 (threshold voltage Vth42 during reverse operation) and a predetermined threshold voltage Vth33. If it is less than the predetermined threshold voltage Vth43 during reverse operation, the connection selector switches S53, S63 are turned off by the control unit 7, while the connection selector switches S51, S61, S52, S62, S54, S64, S55, and S65 are turned on. Then, the first to third current paths and the fourth to sixth current paths are respectively connected in series, and these series connections are connected to each other in parallel. That is, these first to sixth current paths are in a mixed connection state (three series two parallel connection states) in series and parallel to each other.

  Further, when the detected DC high voltage VH (target voltage value of DC high voltage VH during reverse operation) is equal to or higher than threshold voltage Vth33 (threshold voltage Vth43 during reverse operation), control unit 7 As a result, the connection changeover switches S51 to S55 and S61 to S65 are all turned off. Then, the first to sixth current paths are in series connection with each other (six series connection state).

  With such a configuration, in the switching power supply according to the present embodiment, the turn ratio (np / ns) between the turns np of the windings 31A to 31F and the turns ns of the windings 32A and 32B in the transformer 3 is 6 in a parallel connection state. Comparing 2 series 3 parallel state, 3 series 2 parallel state and 6 series connection state, 6 series connection state (turn ratio = 6n) is 6 times larger than 6 parallel connection state (turn ratio = n). Become. In the 3 series 2 parallel connection state (turn ratio = 3n), the size is three times as large as the 6 parallel connection state, and in the 2 series 3 parallel connection state (turn ratio = 2n), it is 2 compared to the 6 parallel connection state. Double the size.

  Therefore, for example, as shown in the graph G3 of FIG. 26, during forward operation, the 2 series 3 parallel connection state is more than the 6 parallel connection state, and the 3 series 2 parallel connection state is more than the 2 series 3 parallel connection state. When the DC high voltage VH as the input voltage is higher in the 6 series connection state than in the 3 series 2 parallel connection state, the drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44, SG51 SG54, SG61 to SG64 can be maintained at a high on-duty ratio, and by performing such connection switching control, an input voltage (DC high voltage) that can maintain a constant output voltage (DC low voltage VL) can be maintained. VH) range becomes wider (from input voltage range VH31 from voltage Vmin3 to voltage Vmax31, from voltage Vmin3 to voltage Vmax32) Be broadened to the input voltage range VH32).

  Also, for example, as shown in the graph G4 of FIG. 27, even in the reverse operation, the 2 series 3 parallel connection state is more than the 6 parallel connection state, and the 3 series 2 parallel connection state is more than the 2 series 3 parallel connection state. When the DC high voltage VH, which is the output voltage, is set higher in the 6 series connection state than in the 3 series 2 parallel connection state, the drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to The on-duty ratios of SG44, SG51 to SG54, and SG61 to SG64 can be kept low. By performing such connection switching control, an output voltage that can be generated from a constant input voltage (DC low voltage VL) ( The range of the DC low voltage VL becomes wider (from the output voltage range VH41 from the voltage Vmin4 to the voltage Vmax41, from the voltage Vmin4 to the voltage Be broadened to the output voltage range VH42 up to max42).

  As described above, in the present embodiment, the six switching circuits 11 to 16, the six high-voltage side windings 31A to 31F and the six inductors Lr1 to Lr6, the connection changeover switches S51 to S55, Since S61 to S65 are provided, the winding ratio between the windings 31A to 31F and the windings 32A and 32B is set to 4 parallel connections, 2 series 3 parallel connections, 3 series 2 parallel connections, and 6 series connections. Compared with the first embodiment, which can be increased in order of connection state and can be increased in order of three connection states (4 parallel connection, 2 series 2 parallel connection, and 4 series connection). Can be further expanded.

  In the present embodiment as well, the current change in the circuit can be moderated by the action of the inductors Lr1 to Lr6 as in the first embodiment. Therefore, it is possible to increase the tolerance for the timing difference between the switching circuits 11 to 16, and it is also possible to widen the voltage range that can be converted while suppressing the generation of the surge current.

[Third embodiment]
Next, a third embodiment of the present invention will be described. The switching power supply according to the present embodiment includes five odd-numbered switching circuits 11 to 15, five high-voltage side windings 31 </ b> A to 31 </ b> E and five inductors Lr <b> 1 to Lr <b> 5 respectively corresponding to the switching circuits 11 to 15. Four connection selector switches S51 to S54 and S61 to S64 are provided. Other configurations are the same as those shown in FIG.

  FIG. 28 shows the details of the current path connection switching control by the control unit 7 in the present embodiment. In this figure, the same components as those shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  In the connection switching control of the present embodiment, first, the DC high voltage VH detected by the voltage detection circuit 61 during forward operation (the target voltage value of the DC high voltage VH during reverse operation) is a predetermined threshold voltage. When it is lower than Vth5 (predetermined threshold voltage Vth6 during reverse operation), the control switch 7 turns on the connection changeover switches S51 to S54 and S61 to S64. Then, five current paths (first to fifth current paths) respectively corresponding to the five switching circuits 11 to 15 and the five high-voltage side windings 31A to 31E are connected in parallel with each other (five parallel connection states). Become.

  On the other hand, when the detected DC high voltage VH (target voltage value of DC high voltage VH during reverse operation) is equal to or higher than threshold voltage Vth5 (threshold voltage Vth6 during reverse operation), control unit 7 As a result, the connection selector switches S51 to S54 and S61 to S64 are all turned off. Then, the first to fifth current paths are in series connection with each other (5 series connection state).

  With such a configuration, in the switching power supply device according to the present embodiment, the winding ratio np / ns between the number of turns np of the windings 31A to 31E and the number of turns ns of the windings 32A and 32B in the transformer 3 is 5 in a parallel connection state. When compared in the 5 series connection state, the 5 series connection state (turn ratio = 5n) is five times larger than the 5 parallel connection state (turn ratio = n).

  Therefore, for example, as shown in the graph G5 of FIG. 29, in the forward operation, when the DC high voltage VH that is the input voltage is higher in the 5 series connection state than in the 5 parallel connection state, the drive signals SG11 to SG14. , SG21 to SG24, SG31 to SG34, SG41 to SG44, SG51 to SG54 can be kept high, and by performing such connection switching control, a constant output voltage (DC low voltage VL) is maintained. Is widened (the input voltage range VH51 from the voltage Vmin5 to the voltage Vmax51 is expanded to the input voltage range VH52 from the voltage Vmin5 to the voltage Vmax52).

  Further, for example, as shown in the graph G6 of FIG. 30, even in the reverse operation, the drive signal is generated even when the DC high voltage VH as the output voltage is set higher in the 5 series connection state than in the 5 parallel connection state. The on-duty ratios of SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44, SG51 to SG54 can be kept low. By performing such connection switching control, a constant input voltage (DC low voltage) The range of the output voltage (DC low voltage VL) that can be generated from the voltage VL is widened (the output voltage range VH61 from the voltage Vmin6 to the voltage Vmax61 is expanded to the output voltage range VH62 from the voltage Vmin6 to the voltage Vmax62). ).

  As described above, also in the present embodiment, the five switching circuits 11 to 15, the five high-voltage side windings 31 </ b> A to 31 </ b> E and the five inductors Lr <b> 1 to Lr <b> 5 corresponding thereto, and the connection changeover switch S <b> 51. Since S54 and S61 to S64 are provided, the current change in the circuit can be moderated by the action of the inductors Lr1 to Lr5 in the same manner as in the first and second embodiments. Therefore, it is possible to increase the tolerance for the timing difference between the switching circuits 11 to 15, and it is possible to realize the widening of the convertible voltage range while suppressing the generation of the surge current.

[Fourth embodiment]
Next, a fourth embodiment of the present invention will be described. The switching power supply device according to the present embodiment corresponds to a case where the number of switching circuits and the like is further increased as compared with the first to third embodiments, and includes 24 switching circuits and transformers 3 respectively corresponding thereto. Are provided with 24 high-voltage side windings, 24 inductors Lr1 to Lr24, and 23 connection changeover switches. Other configurations are the same as those shown in FIG.

  FIG. 31 shows the details of the current path connection switching control by the control unit 7 in the present embodiment. In this figure, the same components as those shown in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  In the connection switching control of the present embodiment, the control unit 7 increases as the DC high voltage VH detected by the voltage detection circuit 61 during forward operation (the target voltage value of the DC high voltage VH increases during reverse operation). The connection state of the 24 current paths (first to 24th current paths) respectively corresponding to the 24 switching circuits and the 24 high-voltage side windings by the on / off control of the connection changeover switch according to FIG. It switches as shown in 31.

  That is, as the detected DC high voltage VH (or the target voltage value of the DC high voltage VH) increases, these connection states are 24 parallel connection state, 2 series 12 parallel connection state, 3 series 8 parallel connection state. 4 series 6 parallel connection state, 6 series 4 parallel connection state, 8 series 3 parallel connection state, 12 series 2 parallel connection state and 12 series connection state are switched in this order.

  With such a configuration, in the switching power supply according to the present embodiment, the turns ratio (np / ns) of the number n of turns of the high-voltage side winding and the number of turns ns of the low-voltage side windings 32A and 32B in the transformer 3 is 24. The turn ratio = n, 2n, 3n, 4n, 6n, 8n, 12n, 24n in the order from the parallel connection state to the 24 series connection state, and the 24 series connection state is 24 times larger than the 24 parallel connection state.

  Therefore, during forward operation, the range of the input voltage (DC high voltage VH) that can maintain a constant output voltage (DC low voltage VL) is further widened. In the reverse operation, the range of the output voltage (DC low voltage VL) that can be generated from a constant input voltage (DC low voltage VL) is further widened.

  As described above, in this embodiment, 24 switching circuits, 24 high-voltage side windings corresponding to these, 24 inductors Lr1 to Lr24, and 23 connection changeover switches respectively. Since it is provided, the turns ratio of the high-voltage side winding and the low-voltage side winding 32A, 32B is 24 parallel connection state, 2 series 12 parallel connection state, 3 series 8 parallel connection state, 4 series 6 parallel connection. State, 6 series 4 parallel connection state, 8 series 3 parallel connection state, 12 series 2 parallel connection state and 12 series connection state can be increased in order of 8 connection states (3 parallel connection order, 4 parallel connection, 2 The first embodiment which can be increased to 2 series connection and 4 series connection), and the order of 4 connection states (6 parallel connection, 2 series 3 parallel connection, 3 series 2 parallel connection and 6 series) Compared to the second embodiment that can be increased in connection), it is possible to further extend the convertible voltage range.

[Fifth embodiment]
Next, a fifth embodiment of the present invention will be described. The switching power supply according to the present embodiment is such that a control unit 70 is provided in place of the control unit 7 in the switching power supply according to the first embodiment.

  FIG. 32 illustrates a configuration of the control unit 70 according to the present embodiment. In this figure, the same components as those shown in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. In the control unit 70 in the first embodiment, a reference power source Ref3, an oscillation circuit 73, a differential amplifier Amp2, a resistor R2, a comparator Comp3, and an arithmetic circuit 74 are further provided. is there.

  The positive input terminal of the comparator Comp1 is connected to one end of the reference power supply Ref3 instead of the reference power supply Ref1. The positive input terminal of the differential amplifier Amp2 is connected to one end of the reference power supply Ref2, the negative input terminal is connected to the output terminal of the voltage detection circuit 62, and the output terminal is connected to the negative input terminal of the comparator Comp2. However, the voltage supplied to the negative input terminal of the differential amplifier Amp2 is greater than the voltage supplied to the negative input terminal of the differential amplifier Amp1, due to, for example, a difference in the extraction position from the voltage dividing resistor in the voltage detection circuit 62. Also set to be slightly higher. The positive input terminal of the comparator Comp3 is connected to the output terminal of the oscillator 73, and the output terminal is connected to the input terminal of the arithmetic circuit 74. Two input terminals of the arithmetic circuit 74 are connected to the output terminal of the comparator Comp3 and the output terminal of the comparator Comp1. The resistor R2 is disposed between the negative input terminal and the output terminal of the differential amplifier Amp2.

  The comparator Comp1 of the present embodiment includes a reference potential V3 from a reference power supply Ref3 corresponding to the potential of the voltage VthH or voltage VthL described later, and a potential of a voltage corresponding to the DC high voltage VH output from the voltage detection circuit 61. And the comparison result is output to the arithmetic circuit 74. Specifically, when the DC high voltage VH is higher than the voltage VthH, the drive signals SG51 to SG53, SG61 to SG63 are at the “L” level, and conversely, when the DC high voltage VH is lower than the voltage VthL. Drive signals SG51 to SG53, SG61 to SG63 attain an “H” level.

  Similar to the differential amplifier Amp1, the differential amplifier Amp2 amplifies and outputs the potential difference between the reference potential V2 from the reference power supply Ref2 and the voltage corresponding to the DC low voltage VL output from the voltage detection circuit 62. To do.

  The comparator Comp3 compares the potential of the pulse voltage PLS3 output from the oscillation circuit 73 with the potential of the output voltage from the differential amplifier Amp2, and based on the comparison result, the connection changeover switches S51 to S53, S61 to S63. The pulse voltage used as the basis of the drive signals SG51 to SG53, SG61 to SG63 is output. Specifically, when the output voltage from the differential amplifier Amp2 is higher than the pulse voltage PLS2, the output is at the “L” level, whereas the output voltage from the differential amplifier Amp2 is lower than the pulse voltage PLS2. In this case, the DC input / output becomes “H” level.

  The arithmetic circuit 74 performs a logical operation based on the output signal (“H” or “L”) from the comparator Comp1 and the output signal (pulse voltage signal) from the comparator Comp3, and performs connection changeover switches S51 to S53, The drive signals SG51 to SG53 and SG61 to SG63 of S61 to S63 are output.

  Here, with reference to FIG. 33, the connection switching operation by the control unit 70 in the forward operation will be described in detail. FIG. 33 shows switching elements S11 to S14, S21 to S24, S31 to S34, S41 to S44 and connection changeover switches S51 to S53, S61 according to the magnitude of the DC high voltage VH that is the input voltage during forward operation. To S63, the connection state of the first to fourth current paths described above, and the turns ratio (np / ns) of the turns np of the windings 31A to 31D and the turns ns of the windings 32A and 32B in the transformer 3 Respectively.

  First, when the DC high-voltage VH is higher than the voltage VthH (VH ≧ VthH), the switching elements S11 to S14, S21 to S24, S31 to S34, and S41 to S44, respectively, as in the first embodiment. The arithmetic circuit 72 drives the drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 so as to perform a PWM (Pulse Width Modulation) operation in which the duty ratio varies according to the magnitude of the DC high voltage VH. To SG44 are output. Further, the arithmetic circuit 74 causes the drive signals SG51 to SG53, SG61 to be connected so that the connection changeover switches S51 to S53 and S61 to S63 are all turned off and the first to fourth current paths are connected in series with each other. SG63 is output. In this case, since the four series connection state, the turn ratio is 4n.

  In addition, when the DC high voltage VH is lower than the voltage VthL (VthL> VH), the switching elements S11 to S14, S21 to S24, S31 to S34, and S41 to S44 are respectively the same as in the first embodiment. The arithmetic circuit 72 outputs drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44, respectively, so as to perform a PWM operation in which the duty ratio varies according to the magnitude of the DC high voltage VH. In addition, the arithmetic circuit 74 drives the drive signals SG51 to SG53, SG61 so that the connection changeover switches S51 to S53 and S61 to S63 are all turned on, and the first to fourth current paths are connected to each other in four parallel connections. SG63 is output. In this case, the turn ratio is n because of the four parallel connection state.

  On the other hand, when the DC high voltage VH is between the voltage VthH and the voltage VthM (VthH> VH ≧ VthM), the switching elements S11 to S14, S21 to S24, S31 to S34, and S41 to S44 are respectively DC high voltage. The arithmetic circuit 72 outputs drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44 so that a PWM operation with a constant duty ratio is performed regardless of the magnitude of VH. The arithmetic circuit 74 outputs drive signals SG51, SG53, SG61, SG63 so that the connection changeover switches S51, S53, S61, S63 are turned off, respectively, while the connection changeover switches S52, S62 are respectively DC high voltage. Drive signals SG52 and SG62 are output so as to perform a PWM operation in which the duty ratio varies according to the magnitude of the voltage VH. Therefore, when the DC high voltage VH is in this voltage range, the connection state of the first to fourth current paths is 4 series or 2 series depending on whether the connection changeover switches S52 and S62 are in the on state or the off state. The time fluctuates between the two parallels, whereby the turns ratio also changes continuously between 4n and 2n.

  When the DC high voltage VH is between the voltage VthM and the voltage VthL (VthM> VH ≧ VthL), the switching elements S11 to S14, S21 to S24, S31 to S34, and S41 to S44 are respectively DC high voltage. The arithmetic circuit 72 outputs drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44 so that a PWM operation with a constant duty ratio is performed regardless of the magnitude of VH. The arithmetic circuit 74 outputs drive signals SG52 and SG62 so that the connection changeover switches S52 and S62 are turned on, respectively, while the connection changeover switches S51, S53, S61, and S63 are respectively large in the DC high voltage VH. The drive signals SG51, SG53, SG61, and SG63 are output so as to perform the PWM operation in which the duty ratio fluctuates accordingly. Therefore, when the DC high voltage VH is in this voltage range, the connection state of the first to fourth current paths is 2 depending on whether the connection changeover switches S51, S53, S61, S63 are in the on state or the off state. It fluctuates in time between the series 2 parallel and the 4 parallel, whereby the turn ratio also changes continuously between 2n and n.

  With this configuration, similarly to the control unit 7, the control unit 70 drives the drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, based on the voltage corresponding to the DC low voltage VL output from the voltage detection circuit 62. SG41 to SG44 are generated, and thereby the switching elements S11 to S14, S21 to S24, S31 to S34, and S41 to S44 are turned on / off to stabilize (keep constant) the DC low voltage VL. It has become.

  The drive signals SG51 to SG53 are based on the magnitude of the voltage according to the DC high voltage VH output from the voltage detection circuit 61 and the magnitude of the voltage according to the DC low voltage VL output from the voltage detection circuit 62. , SG61 to SG63, and thereby controlling the operation of the connection changeover switches S51 to S53, S61 to S63, a current path (first current path) passing through the switching circuit 11 and the winding 31A, a switching circuit 12 and a current path passing through the winding 31B (second current path), a current path passing through the switching circuit 13 and the winding 31C (third current path), and a current passing through the switching circuit 14 and the winding 31D. The connection state of the path (fourth current path) is switched. Specifically, the first to fourth current paths are connected in series to each other 4 in series connection duty ratio, 2 in series 2 in parallel connection 2 in series 2 in parallel connection, and 4 in parallel to each other By changing the duty ratios of the four parallel connection states, the turns ratio (np / ns) between the turns np of the windings 31A to 31D and the turns ns of the windings 32A and 32B in the transformer 3 is continuously changed. It has become.

  Next, referring to FIGS. 34 to 38, the switching power supply device of this embodiment (having the control unit 70 shown in FIG. 32) and the switching power supply device of the first embodiment (comparative example; FIG. 2) and the connection switching control when the DC high voltage VH that is the input voltage changes during forward operation.

  Here, FIGS. 34 and 35 show timing waveforms of connection switching control according to the comparative example. FIG. 34 shows that the DC high voltage VH is larger than the threshold voltage Vth12 and becomes smaller than this. FIG. 35 shows timing waveforms until the DC high voltage VH is higher than the threshold voltage Vth11 until it becomes smaller than this. On the other hand, FIGS. 36 and 37 show timing waveforms of the connection switching control according to the present embodiment, and FIG. 36 shows a case where the DC high voltage VH decreases from the voltage VthH to the voltage VthM. FIG. 37 shows a timing waveform until the DC high voltage VH decreases from the voltage VthM to the voltage VthL. Specifically, in FIGS. 34 to 37, (A) shows the DC high voltage VH, (B) shows the drive signals SGm1, SGm3 (m = 1 to 4), and (C) shows the drive signals SGm2, SGm4. (M = 1 to 4), (D) shows drive signals SG51 and SG61, (E) shows drive signals SG52 and SG62, (F) shows drive signals SG53 and SG63, and (G) shows center tap CT. (H) represents the DC low voltage VL. FIG. 38 shows the relationship between the input voltage, the duty ratio, and the connection state by the control unit 70 of the present embodiment, and corresponds to FIG. 10 in the comparative example (first embodiment). It is. 34 to 37, the 4 series connection state is represented as “4s”, the 2 series 2 parallel connection state is represented as “2s2p”, and the 4 parallel connection state is represented as “4p”.

  First, in the comparative example shown in FIG. 34, when the DC high voltage VH ((A)) is higher than the threshold voltage Vth12 (timing t120 to t121), the connection changeover switches S51 to S53 and S61 to S63 are switched. The drive signals SG51 to SG53, SG61 to SG63 are turned off ((D) to (F)), and the first to fourth current paths are connected in series with each other, while the DC high voltage VH is a threshold voltage. When it becomes lower than Vth12 (after timing t121), the drive signals SG52 and SG62 are turned on ((E)), and the first to fourth current paths are in a two-series two-parallel connection state. That is, the connection changeover switches S51 to S53 and S61 to S63 are controlled so that the control unit 7 switches the on / off state depending on whether or not the DC high voltage VH is higher than the predetermined threshold voltage Vth12. Made.

  In the comparative example shown in FIG. 35, when the DC high voltage VH ((A)) is higher than the threshold voltage Vth11 (timing t123 to t124), the drive signals SG51, SG53, SG61, SG63 are turned off. And the drive signals SG52 and SG63 are in the on state ((D) to (F)), and the first to fourth current paths are connected in two series and two in parallel, while the DC high voltage VH is When it becomes lower than the threshold voltage Vth11 (after timing t124), the drive signals SG51, SG53, SG61, SG63 are also turned on ((D), (F)), and the first to fourth current paths are connected in parallel to each other. It becomes a state. That is, also in this case, the connection changeover switches S51 to S53 and S61 to S63 are switched on and off by the control unit 7 depending on whether or not the DC high voltage VH is higher than a predetermined threshold voltage Vth11. Control.

  The drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44 ((B), (C)) of the switching elements S11 to S14, S21 to S24, S31 to S34, S41 to S44 are DC high voltage. In order to prevent the DC low voltage VL from fluctuating due to the change in VH, the control unit 7 controls the duty ratio to change so that the DC low voltage VL ((H)) is kept constant. It is supposed to be kept.

  However, for example, when switching from the 4 series connection state to the 2 series 2 parallel connection state at the timing t121, or when switching from the 2 series 2 parallel connection state to the 4 parallel connection state at the timing t124, they are indicated by reference numerals G4 and G5, respectively. As described above, overshoot occurs in the DC low voltage VL, and the DC low voltage VL cannot be kept constant in the period from the timing t121 to t122 and from t124 to t125. This is because the connection state is rapidly switched at timings t121 and t124, so that the response speed of the differential amplifier Amp1 (error amplifier) in the control unit 7 cannot catch up, and the tap voltage VCT ((G)) in the center diagram is an arrow. , The duty ratios of the drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44 change abruptly (abrupt changes in the threshold voltages Vth11 and Vth12 shown in FIG. 10). It is because it is not possible. In this way, in the comparative example, the duty ratios of the drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44 are slightly increased at the timings t121 to t122 and t124 to t125. Shooting will occur.

  On the other hand, in the present embodiment, when the DC high voltage VH changes between the voltage VthH and the voltage VthM as shown in FIG. 36, as described above, the magnitude of the DC low voltage VL ( That is, the operation of the connection changeover switches S51 to S53, S61 to S63 is indirectly controlled according to the DC high voltage VH), and the duty ratios of the 4 series connection state and the 2 series 2 parallel connection state are changed. Thus, the turns ratio (np / ns) between the turns np of the windings 31A to 31D and the turns ns of the windings 32A and 32B in the transformer 3 is continuously changed.

  Also, as shown in FIG. 37, even when the DC high voltage VH changes between the voltage VthM and the voltage VthL, it depends on the magnitude of the DC low voltage VL (indirect magnitude of the DC high voltage VH). By controlling the operation of the connection changeover switches S51 to S53 and S61 to S63 and changing the duty ratios of the 2 series 2 parallel connection state and the 4 parallel connection state, the turn ratio (np / ns) in the transformer 3 is continuously increased. It is supposed to change.

  Further, since the voltage supplied to the negative input terminal of the differential amplifier Amp2 is set to be slightly higher than the voltage supplied to the negative input terminal of the differential amplifier Amp1, the drive signals SG11 to SG14, SG21 are set. ~ SG24, SG31 to SG34, SG41 to SG44 (FIG. 36, (B), (C) in FIG. 37) have constant duty ratios. Therefore, the voltage waveform of the center tap voltage VCT is as shown in FIGS. 36 (G) and 37 (G), and the integrated value (area) thereof is always constant. Therefore, the DC low voltage VL ((H )) Does not cause an overshoot and is always kept constant.

  Thus, in the switching power supply of the present embodiment, for example, as indicated by reference numeral G6 in FIG. 38, when the DC high voltage VH is between the voltage VthH and the voltage VthL, the drive signals SG11 to SG14, SG21 to While the duty ratios of SG24, SG31 to SG34, and SG41 to SG44 are constant, the duty ratios of the drive signals SG52 and SG62 and the drive signals SG51, SG53, SG61, and SG63 are indicated by reference numerals G7 and G8 in the figure, respectively. The duty ratio changes continuously.

  36 and 37 show the case where the DC high voltage VH changes between the voltage VthH and the voltage VthL. However, when the DC high voltage VH is VthH or higher or VthL or lower, for example, FIG. As described above, the duty ratios of the drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44 are also displaced by a constant change amount.

  As described above, in the present embodiment, the duty ratios of the 4 parallel connection state, the 2 series 2 parallel connection state, and the 4 series connection state are changed according to the magnitude of the DC high voltage VH. The value of can be continuously changed, and a sudden change can be avoided. Therefore, even when there is an element with a slow response speed (for example, the above-described error amplifier) in the switching device, the number of turns np of the windings 31A to 31D and the number of turns ns of the windings 32A and 32B in the transformer 3 Can be continuously changed (increased or decreased), and the DC low voltage VL can be stabilized regardless of the response speed of each element.

  In the present embodiment, the duty ratios of drive signals SG51 to SG53, SG61 to SG63 change, and the duty ratios of drive signals SG11 to SG14, SG21 to SG24, SG31 to SG34, and SG41 to SG44 change. However, the duty ratios of the two may be changed.

  In the present embodiment, the switching control by the control unit 70 is not limited to the voltage waveform of the center tap voltage VCT as shown in FIGS. 36 and 37. For example, FIG. 39 and FIG. 40 may be used. Even when configured as described above, it is possible to obtain the same effects as those of the present embodiment. However, when the switching circuits 11 to 14 perform the above-described phase shift operation, the zero-volt switching operation can be performed with the voltage waveforms shown in FIGS.

  In the present embodiment, the comparator Comp1 and the reference power supply Ref3 are provided in the control unit 70. However, when the DC high voltage VH is changed between the voltage VthH and the voltage VthL, these are not provided. The arithmetic circuit 74 may generate the drive signals SG51 to SG53, SG61 to SG63 based only on the output signal from the comparator Comp3.

  In the present embodiment, the forward operation for generating the DC low voltage VL from the DC high voltage VH has been described. However, the forward operation is also applied to the reverse operation for generating the DC high voltage VH from the DC low voltage VL. It is possible to obtain the same effect by the same operation as in the above case.

  Furthermore, the switching control by the control unit 70 as described in the present embodiment can be applied to other embodiments of the present invention, and the same effect can be obtained.

  Although the present invention has been described with reference to the first to fifth embodiments, the present invention is not limited to these embodiments, and various modifications can be made.

  For example, in the above-described embodiment, the case where the number of high-voltage side switching circuits is four, six, five, or 24 has been described, but the number of switching circuits is not limited to these cases. However, when the number of switching circuits is N (natural number of 4 or more), it is preferable to set the value of N so that there are three or more divisors of N. Thus, when there are three or more divisors of N, there are three or more connection states of current paths, that is, in addition to N parallel connection states and N serial connection states, This is because a mixed connection state can be provided and the convertible voltage range can be expanded. Therefore, in the present invention, it is desirable to set the divisor of N to be as large as possible.

  In the above-described embodiment, the case where the connection is switched according to the target voltage value of the output voltage (DC high voltage VH) during the reverse operation has been described. However, the reverse operation is the same as the forward operation. The connection may be switched according to the magnitude of the input voltage (DC low voltage VL) detected by the voltage detection circuit 62. In the case of such a configuration, for example, as in the forward operation, the range of the input voltage (DC low voltage VL) that can maintain a constant output voltage (DC high voltage VH) can be expanded compared to the conventional case. Become. In this case, in contrast to the forward operation, as the detected DC low voltage VL increases, the current paths are connected in series, in a mixed connection state in series connection and parallel connection, in parallel connection state. The connection is switched in this order, and the turn ratio (np / ns) between the number of turns np of the primary side winding and the number of turns ns of the secondary side winding in the transformer may be continuously reduced.

  In the above embodiment, the connection switching is performed according to the target voltage value of the output voltage (DC high voltage VH) during reverse operation. Similarly, the output voltage (DC high voltage) is also used during forward operation. The connection may be switched according to the target voltage value of voltage VL). In such a configuration, the range of the output voltage (DC high voltage VH) that can be generated from a constant input voltage (DC low voltage VL) is widened, for example, as in reverse operation.

  In the above-described embodiment, the switching circuit 4 is described as a center tap type anode common connection circuit (or push-pull type circuit). However, for example, a full bridge type circuit or a cathode common connection is used. You may make it comprise by the circuit of.

  In the above embodiment, the switching power supply device is described as a step-down type, but the present invention can also be applied to a step-up type switching power supply device.

It is a circuit diagram showing the structure of the switching power supply device which concerns on the 1st Embodiment of this invention. It is a circuit diagram showing the structure of the control part of FIG. It is a figure for demonstrating the connection state which concerns on 1st Embodiment. FIG. 2 is a circuit diagram for explaining an operation in a four parallel connection state in a forward direction in the switching power supply device of FIG. 1. FIG. 5 is a circuit diagram for explaining the operation in the four parallel connection state in the forward direction following FIG. 4. FIG. 2 is a circuit diagram for explaining an operation in a 2-series / 2-parallel connection state in the forward direction in the switching power supply device of FIG. 1. It is a circuit diagram for demonstrating operation | movement of the 2 series 2 parallel connection state at the time of the forward direction following FIG. FIG. 2 is a circuit diagram for explaining an operation in a four-series connection state in a forward direction in the switching power supply device of FIG. 1. It is a circuit diagram for demonstrating operation | movement of the 4 series connection state at the time of the forward direction following FIG. It is a characteristic view showing the relationship between the input voltage at the time of forward operation in 1st Embodiment, a duty ratio, and a connection state. It is a circuit diagram showing the structure of the switching power supply device which concerns on a comparative example. It is a timing waveform diagram for demonstrating the forward direction operation | movement of the switching power supply which concerns on a comparative example. FIG. 2 is a timing waveform diagram for explaining a forward operation of the switching power supply device of FIG. 1. FIG. 3 is a circuit diagram for explaining an operation in a four parallel connection state in the reverse direction in the switching power supply device of FIG. 1. It is a circuit diagram for demonstrating the operation | movement of the 4 parallel connection state at the time of the reverse direction following FIG. FIG. 2 is a circuit diagram for explaining an operation in a 2-series / 2-parallel connection state in the reverse direction in the switching power supply device of FIG. 1. It is a circuit diagram for demonstrating the operation | movement of the 2 series 2 parallel connection state at the time of the reverse direction following FIG. FIG. 3 is a circuit diagram for explaining an operation in a four-series connection state in the reverse direction in the switching power supply device of FIG. 1. It is a circuit diagram for demonstrating the operation | movement of the 4 series connection state at the time of the reverse direction following FIG. It is a characteristic view showing the relationship between the input voltage at the time of reverse operation | movement in 1st Embodiment, a duty ratio, and a connection state. It is a circuit diagram for demonstrating the operation | movement of the 4 series connection state at the time of the forward direction which concerns on the modification of 1st Embodiment. It is a circuit diagram for demonstrating operation | movement of the 4-series connection state at the time of the forward direction following FIG. It is a circuit diagram for demonstrating operation | movement of the 2 series 2 parallel connection state at the time of the forward direction which concerns on the modification of 1st Embodiment. It is a circuit diagram for demonstrating operation | movement of the 2 series 2 parallel connection state at the time of the forward direction following FIG. It is a figure for demonstrating the connection state which concerns on the 2nd Embodiment of this invention. It is a characteristic view showing the relationship between the input voltage at the time of the forward operation in 2nd Embodiment, a duty ratio, and a connection state. It is a characteristic view showing the relationship between the input voltage at the time of reverse operation | movement in 2nd Embodiment, a duty ratio, and a connection state. It is a figure for demonstrating the connection state which concerns on the 3rd Embodiment of this invention. It is a characteristic view showing the relationship between the input voltage at the time of forward operation in 3rd Embodiment, a duty ratio, and a connection state. It is a characteristic view showing the relationship between the input voltage at the time of reverse operation | movement in 3rd Embodiment, a duty ratio, and a connection state. It is a figure for demonstrating the connection state which concerns on the 4th Embodiment of this invention. It is a circuit diagram showing the structure of the control part in the switching power supply which concerns on the 5th Embodiment of this invention. It is a figure for demonstrating the connection switching operation | movement by the control part of FIG. FIG. 3 is a timing waveform diagram for explaining a connection switching operation by the control unit of FIG. 2. FIG. 35 is a timing waveform chart for explaining a connection switching operation following FIG. FIG. 33 is a timing waveform chart for explaining a connection switching operation by the control unit of FIG. 32. FIG. 37 is a timing waveform chart for explaining a connection switching operation following FIG. It is a characteristic view showing the relationship between the input voltage at the time of forward operation in 5th Embodiment, a duty ratio, and a connection state. It is a timing waveform diagram for demonstrating the connection switching operation | movement which concerns on the modification of 5th Embodiment. It is a timing waveform diagram for demonstrating the connection switching operation | movement which concerns on the modification of 5th Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11-14,4 ... Switching circuit, 3 ... Transformer, 31A-31D ... 1st winding, 32A, 32B ... 2nd winding, 51 ... High voltage battery, 52 ... Low voltage battery, 61, 62 ... Voltage detection circuit , 7, 70 ... control unit, 71, 73 ... oscillation circuit, 72, 74 ... arithmetic circuit, S11 to S14, S21 to S24, S31 to S34, S41 to S44, S10, S20 ... switching elements, S51 to S53, S61 ~ S63 ... connection changeover switch, D11 ~ D14, D21 ~ D24, D31 ~ D34, D41 ~ D44, D10, D20 ... diode, CH, CL ... smoothing capacitor, T1 ~ T4 ... input / output terminal, L1H, L2H ... high voltage line , L1L, L2L ... Low voltage line, Lr1-Lr4, Lch ... Inductor, P1-P26 ... Connection point, CT ... Center tap, VCT ... Tap voltage, VH ... DC high voltage, VL ... DC low voltage, Comp1-Comp3 ... Comparator, Amp1, Amp2 ... Differential amplifier (error amplifier), Ref1-Ref3 ... Reference power supply, V1-V3 ... Reference potential, R1 ... Resistor, PLS1, PLS2 ... pulse voltage, Ip11-Ip14, Ip21-Ip24, Ip31-Ip34, Ip41-Ip44, Is1-Is6, Isp11, Isp12, Isp21, Isp22, Isp31, Isp32, Isp41, Isp42, Isp51, Isp52, Isp61, Isp62, Ixa to Ixd ... current, SG11 to SG14, SG21 to SG24, SG31 to SG34, SG41 to SG44, SG10, SG20, SG51 to SG53, SG61 to SG63 ... switching signals, t1, t20 to t31: Timing.

Claims (20)

A switching power supply device comprising a first terminal pair and a second terminal pair for performing voltage conversion between the first DC voltage on the first terminal side and the second DC voltage on the second terminal pair side. And
A transformer having a plurality of first windings arranged on the first terminal pair side and having the same number of turns, and a second winding arranged on the second terminal pair side;
A plurality of first circuits of a full bridge type provided on the first terminal pair side corresponding to the plurality of first windings, each including four switching elements;
A plurality of current paths composed of the plurality of first circuits and the first windings respectively corresponding to the plurality of first circuits are connected in parallel to each other, in series connection, or in series and parallel mixed connection A switching power supply comprising: connection switching means for performing connection switching so that In the case of converting the input first DC voltage to output the second DC voltage,
The switching power supply unit according to claim 1, wherein the connection switching unit performs connection switching according to the magnitude of the first DC voltage. The switching power supply unit according to claim 2, wherein the connection switching unit performs connection switching in the order of parallel connection, mixed connection, and series connection as the first DC voltage increases. In the case of converting the input second DC voltage to output the first DC voltage,
The switching power supply unit according to claim 1, wherein the connection switching unit performs connection switching in accordance with the magnitude of the second DC voltage. The switching power supply unit according to claim 4, wherein the connection switching means performs connection switching in the order of series connection, mixed connection, and parallel connection as the second DC voltage increases. The connection switching means is
A plurality of connection switching elements;
A voltage detection circuit for detecting the first DC voltage or the second DC voltage;
And a first control unit that controls on / off states of the plurality of connection switching elements according to the magnitude of the first or second DC voltage detected by the voltage detection circuit. The switching power supply device according to any one of claims 2 to 5. The connection switching means compares the values of the first or second DC voltage with a predetermined plurality of threshold voltages, and performs connection switching based on the comparison result. The switching power supply device according to any one of claims 2 to 6. The connection switching means includes a duty ratio in the parallel connection state, a duty ratio in the mixed connection state, and a duty ratio in the series connection state according to the magnitude of the first or second DC voltage. The switching power supply device according to any one of claims 2 to 6, wherein connection switching is performed so that at least two of these change. The connection switching means continuously increases a turns ratio between the first winding and the second winding as the first DC voltage increases, and the second DC 9. The switching power supply device according to claim 8, wherein the duty ratio of the connection state is changed so that the turn ratio continuously decreases as the voltage increases. In the case of converting the input second DC voltage to output the first DC voltage,
4. The switching power supply device according to claim 1, wherein the connection switching unit performs connection switching so that the first DC voltage becomes a predetermined target voltage value. 5. The connection switching means is
A plurality of connection switching elements;
The switching power supply according to claim 10, further comprising: a second control unit that controls on / off states of the plurality of connection switching elements according to the magnitude of the target voltage value. The switching power supply unit according to claim 10 or 11, wherein the connection switching unit performs connection switching in the order of parallel connection, mixed connection, and series connection as the target voltage value increases. Comprising four said first circuits;
13. The connection state of the four current paths includes a four parallel connection state, a mixed connection state of two series and two parallels, and a four series connection state. 13. The switching power supply device described in 1. Comprising six said first circuits;
The connection states of the six current paths include six parallel connection states, two series and three parallel mixed connection states, three series and two parallel mixed connection states, and six series connection states. The switching power supply device according to any one of claims 1 to 12. The number of the first circuits is N (natural number of 4 or more), and there are three or more divisors of N. 13. Switching power supply. The switching according to any one of claims 1 to 15, wherein each of the four switching elements always performs an on / off operation regardless of a connection state of the plurality of current paths. Power supply. Each of the four switching elements is in an on / off operation state or an on state in accordance with a connection state of the plurality of current paths. The switching power supply device described. The switching power supply device according to any one of claims 1 to 17, further comprising a center tap type or push-pull type second circuit on the second terminal pair side. The switching power supply according to any one of claims 1 to 17, further comprising a full-bridge second circuit on the second terminal pair side. A switching power supply device comprising a first terminal pair and a second terminal pair for performing voltage conversion between a first DC voltage on the first terminal pair side and a second DC voltage on the second terminal pair side. There,
A transformer having a plurality of first windings arranged on the first terminal pair side and having the same number of turns, and a second winding arranged on the second terminal pair side;
A plurality of full-bridge circuits each provided on the first terminal pair side corresponding to the plurality of first windings, each including four switching elements;
A driving circuit for driving the plurality of circuits in synchronization with each other;
A plurality of inductors provided corresponding to the plurality of circuits, and
Connection switching means for switching connection so that a plurality of current paths constituted by the plurality of circuits and the first windings respectively corresponding to the plurality of circuits are connected in parallel or in series with each other. A switching power supply device characterized by that.

Images