Switching power supply device

Abstract

The technical problem of the present invention is to provide a switching power supply device capable of making coupling coefficients of a plurality of secondary windings of a transformer with respect to a primary winding consistent and capable of eliminating current imbalance. This switching power supply device is provided with a planar transformer having, on the primary side thereof, a bridge in which a plurality of switching elements are connected in series, and a primary winding. The switching elements include the switching element controlled at a first ON time, and the switching element controlled at a second ON time different from the first ON time.

Description

Technical Field

[0001] The present disclosure relates to a switching power supply device. Background Art

[0002] As the power supply device, a switching power supply device is used.

[0003] Patent Document 1 discloses a current resonance power supply transformer that achieves nearly equal coupling between two secondary windings and one primary winding (see Patent Document 1). Patent Document 1 has a structure in which an interlayer tape is sandwiched between a lead wire connected to a first secondary winding and a second secondary winding adjacent to the lead wire.

[0004] In Patent Document 1, for example, the thickness of the interlayer tape or the number of turns is used to achieve a nearly equal coupling degree between two secondary windings and one primary winding. In Patent Document 1, for example, the primary winding is wound around the outside of the two secondary windings, and the interlayer tape is wound around the outside of one secondary winding and the interlayer tape is wound around the inside of the other secondary winding, so that the coupling degree between two secondary windings and one primary winding is nearly equal is achieved.

[0005] In Patent Document 1, for example, two secondary windings are alternately wound one by one adjacent to one primary winding, thereby achieving nearly equal coupling with the primary winding at height positions relative to each secondary winding.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2017-126675 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, in the conventional technology as described above, even if the coupling degrees of the secondary windings are equal ideally, deviations may occur in reality.

[0011] For example, in a center-tapped half-bridge (HB)-LLC converter having two secondary windings on the output side, a deviation may occur in the L value or coupling degree between the two secondary windings.

[0012] As a result of such a deviation, for example, the output current may also become uneven, resulting in various disadvantages.

[0013] The present disclosure has been made in consideration of such a situation, and an object of the present disclosure is to provide a switching power supply device that can make the coupling coefficients of a plurality of secondary windings of a transformer consistent with the primary winding and eliminate current imbalance.

[0014] Technical solutions to the problem

[0015] A switching power supply device of one embodiment comprises: a planar transformer, wherein on the primary side of the transformer, there are: a bridge composed of a plurality of switching elements connected in series, and a primary winding, wherein the switching elements include: the switching elements controlled with a first on-time, and the switching elements controlled with a second on-time different from the first on-time.

[0016] Effects of the Invention

[0017] According to the present disclosure, in the switching power supply device, the coupling coefficients of the plurality of secondary windings of the transformer with respect to the primary winding can be made uniform, and current imbalance can be eliminated. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a diagram showing a configuration example of a circuit of a switching power supply device according to an embodiment.

[0019] Figure 2 It is a diagram showing a schematic configuration example of a planar transformer structure of a winding of a switching power supply device according to an embodiment.

[0020] Figure 3 This is a diagram showing an example of a control voltage when the high side and low side duty ratios are equal according to the embodiment.

[0021] Figure 4 This is a diagram showing an example of a control voltage when the high side is corrected according to the embodiment.

[0022] Figure 5 This is a diagram showing an example of the control voltage when the high side and the low side are corrected according to the embodiment.

[0023] Fig. 6A This is a diagram showing an example of current flowing through two switching elements in a comparative example.

[0024] Figure 6B This is a diagram showing an example of current flowing through two diodes of a comparative example.

[0025] Figure 6C This is a diagram showing an example of current flowing through two switching elements according to the embodiment.

[0026] Fig.6D This is a diagram showing an example of current flowing through two diodes according to the embodiment.

[0027] Fig. 7A 1 is a diagram showing an example of currents flowing through two switching elements of a comparative example when the load current Io is 21A.

[0028] Figure 7B 1 is a diagram showing an example of currents flowing through two diodes of a comparative example when the load current Io is 21A.

[0029] Figure 7C 1 is a diagram showing an example of currents flowing through two switching elements according to the embodiment when the load current Io is 21A.

[0030] Fig.7D 1 is a diagram showing an example of currents flowing through two diodes according to the embodiment when the load current Io is 21A.

[0031] Fig. 8A 1 is a diagram showing an example of currents flowing through two switching elements of a comparative example when the load current Io is 10A.

[0032] Figure 8B 1 is a diagram showing an example of currents flowing through two diodes of a comparative example when the load current Io is 10A.

[0033] Figure 8C 1 is a diagram showing an example of currents flowing through two switching elements according to the embodiment when the load current Io is 10A.

[0034] Fig.8D 1 is a diagram showing an example of currents flowing through two diodes according to the embodiment when the load current Io is 10A.

[0035] Fig.9A 1 is a diagram showing an example of currents flowing through two switching elements of a comparative example when the load current Io is 5A.

[0036] Fig. 9B 1 is a diagram showing an example of currents flowing through two diodes of a comparative example when the load current Io is 5A.

[0037] Fig. 9C 1 is a diagram showing an example of currents flowing through two switching elements according to the embodiment when the load current Io is 5A.

[0038] Fig.9D 1 is a diagram showing an example of currents flowing through two diodes according to the embodiment when the load current Io is 5A.

[0039] Fig. 10AThis is a diagram showing an example of currents flowing through two switching elements in the embodiment when the input voltage Vin is 400 V and fixed correction is used.

[0040] Fig. 10B This is a diagram showing an example of currents flowing through two diodes according to the embodiment when the input voltage Vin is 400 V and fixed correction is used.

[0041] Fig. 10C This is a diagram showing an example of currents flowing through two switching elements according to the embodiment when the input voltage Vin is 350 V and fixed correction is used.

[0042] Fig. 10D This is a diagram showing an example of currents flowing through two diodes according to the embodiment when the input voltage Vin is 350 V and fixed correction is used.

[0043] Fig.10E This is a diagram showing an example of currents flowing through two switching elements according to the embodiment when the input voltage Vin is 300 V and fixed correction is used.

[0044] Fig.10F This is a diagram showing an example of currents flowing through two diodes according to the embodiment when the input voltage Vin is 300 V and fixed correction is used.

[0045] Figure 10G This is a diagram showing an example of currents flowing through two switching elements in the embodiment when the input voltage Vin is 350 V and variable correction is used.

[0046] Fig. 10H This is a diagram showing an example of currents flowing through two diodes according to the embodiment when the input voltage Vin is 350 V and variable correction is used.

[0047] Fig.10I This is a diagram showing an example of currents flowing through two switching elements according to the embodiment when the input voltage Vin is 300 V and variable correction is used.

[0048] Fig.10J This is a diagram showing an example of currents flowing through two diodes according to the embodiment when the input voltage Vin is 300 V and variable correction is used.

[0049] Fig.11 It is a diagram showing an example of a variable correction table according to the embodiment.

[0050] Description of Reference Numerals

[0051] 1…switching power supply device; 11…DC power supply; 12, 63…capacitor; 13…inductor; 14…primary winding; 61, 62…secondary winding; 64…load; 111…controller; 131…memory; 211…printed substrate; 231-232…core material; 261-262, 271-272 winding pattern; A1, A2, A11-A12, A21-A22…control voltage; B1-B2, B11-B12, B101-B102, B111-B112, B121-B122, B131-B132, B141-B142, B1 51~B152、B201~B202、B211~B212、B221~B222、B301~B302、B311~B312、C1~C2、C11~C12、C101、C102、C111~C112、C121~C122、C131~C132、C141~C142、C151~C152、C201~C202、C211~C212、C221~C222、C301~C302、C311~C312…current;1011…variable correction meter;D1、D2…diode;H1…air gap;J1…core;Q1、Q2…transistor;G1、G2…grounding portion;Tr1…transformer DETAILED DESCRIPTION

[0052] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0053] [Switching power supply device]

[0054] Figure 1 1 is a diagram showing a configuration example of a circuit of the switching power supply device 1 according to the embodiment.

[0055] Figure 2 1 is a diagram showing a schematic configuration example of a planar transformer configuration of a winding of the switching power supply device 1 according to the embodiment.

[0056] In the present embodiment, a switching power supply device 1 using a center-tapped half-bridge (HB)-LLC converter is described as an example.

[0057] <Example of a circuit for a switching power supply device>

[0058] Reference Figure 1 , a configuration example of a circuit of the switching power supply device 1 according to the present embodiment will be described.

[0059] The switching power supply device 1 includes: a DC power supply 11, a transistor Q1, a transistor Q2, a capacitor 12, an inductor 13, a primary winding 14 constituting a transformer Tr1, two secondary windings constituting the transformer Tr1, namely, a secondary winding 61 and a secondary winding 62, a diode D1, a diode D2, a capacitor 63, a load 64, and a controller 111.

[0060] The controller 111 has a memory 131 .

[0061] Here, in this embodiment, the transistor Q1 and the transistor Q2 are both field effect transistors (FET: Field Effect Transistor), but they may also be other switching devices.

[0062] The connection relationship of the circuit is described.

[0063] The positive (+) terminal of the DC power supply is connected to the drain (D) terminal of the transistor Q1.

[0064] In the present embodiment, the voltage of the positive (+) terminal of the DC power supply is referred to as an input voltage Vin.

[0065] A source (S) terminal of the transistor Q1 , a drain (D) terminal of the transistor Q2 , and one end of the capacitor 12 are connected.

[0066] The other end of the capacitor 12 is connected to one end of the inductor 13 .

[0067] The other end of the inductor 13 is connected to one end of the primary winding 14 .

[0068] A negative (−) terminal of the DC power source, a source (S) terminal of the transistor Q2 , and the other end of the primary winding 14 are connected.

[0069] In the present embodiment, the negative electrode (−) terminal of the DC power supply is connected to the ground portion G1 and is grounded.

[0070] One end of the secondary winding 62 is connected to the cathode of the diode D2.

[0071] The other end of the secondary winding 62 , one end of the secondary winding 61 , one end of the capacitor 63 , and one end of the load 64 are connected.

[0072] The other end of the secondary winding 61 is connected to the cathode of the diode D1 .

[0073] The anode of the diode D1 , the anode of the diode D2 , the other end of the capacitor 63 , and the other end of the load 64 are connected.

[0074] In this embodiment, the other end of the load 64 is connected to the ground portion G2 and grounded. Here, in this embodiment, the ground portion G1 and the ground portion G2 are separate ground potentials, and are separated into a primary circuit and a secondary circuit.

[0075] The controller 111 is connected to the gate (G) terminal of the transistor Q1 , and has a function of outputting (applying) a control voltage to the gate (G) terminal of the transistor Q1 .

[0076] In addition, the controller 111 is connected to the gate (G) terminal of the transistor Q2 and has a function of outputting (applying) a control voltage to the gate (G) terminal of the transistor Q2.

[0077] The controller 111 is connected to one end of the load 64 and has a function of detecting a voltage at the connection point (referred to as an output voltage Vo in the present embodiment).

[0078] Here, the function of the controller 111 may be implemented by using, for example, a microcomputer.

[0079] In this embodiment, the control voltage is a value that can change with time and has parameters of time and level (voltage). In addition, the control voltage in this embodiment can also be called a control signal, a voltage signal, or a control voltage signal.

[0080] In this embodiment, for convenience of description, one transistor Q1 is described as a high-side transistor and the other transistor Q2 is described as a low-side transistor.

[0081] In the present embodiment, the controller 111 has a function of performing fixed correction control or variable correction control on the control voltages of the two transistors Q1 and Q2.

[0082] Here, the fixed correction control is a control in which the correction amount is fixed, and the variable correction control is a control in which the correction amount is variable according to a predetermined index value.

[0083] <Example of operation of a switching power supply device>

[0084] The controller 111 performs control in the primary side circuit in a manner that repeats the following states, namely, a state in which the transistor Q1 is turned on and the transistor Q2 is turned off, a state in which the transistor Q1 and the transistor Q2 are turned off together, a state in which the transistor Q1 is turned off and the transistor Q2 is turned on, and a state in which the transistor Q1 and the transistor Q2 are turned off together.

[0085] By this control, a predetermined current flows through the primary winding 14 of the transformer Tr1 in each state (mode), and a corresponding current flows through the two secondary windings 61 and 62, thereby obtaining a predetermined output voltage Vo.

[0086] In addition, the controller 111 may detect the output voltage Vo, for example, and perform feedback control on the primary side based on the detection result.

[0087] <Planar Transformer Structure>

[0088] Figure 2 1 is a diagram showing a schematic configuration example of a planar transformer configuration of a winding of the switching power supply device 1 according to the embodiment.

[0089] exist Figure 2 In the figure, for the convenience of explanation, the three-dimensional rectangular coordinate axes, namely the XYZ rectangular coordinate axes, are shown. Figure 2 In the example of FIG. 1 , an example of the shape of a cross section viewed from the side when an E-shaped core material 231 and an I-shaped core material 232 are arranged to face each other in the up-down direction is schematically shown.

[0090] In the planar transformer structure of the present embodiment, winding patterns 261 to 262 and 271 to 272 are printed on a printed substrate 211. The printed substrate 211 is combined with the core J1 to assemble the transformer.

[0091] exist Figure 2 In the example of FIG. 1 , the core J1 is an EI type core. The core J1 is formed by using a plurality of core materials 231 to 232. An air gap H1 is provided between the core material 231 and the core material 232.

[0092] exist Figure 2 In the example of FIG. 1 , the air gap H1 becomes asymmetric with respect to the vertical direction, thereby causing an unbalance.

[0093] The winding patterns 261 - 262 form a primary winding 14 .

[0094] The winding pattern 271 forms a secondary winding 61 .

[0095] The winding pattern 272 forms another secondary winding 62 .

[0096] In the present embodiment, the two secondary windings 61 and 62 are arranged at symmetrical positions with respect to the primary winding 14 .

[0097] In addition, in the present embodiment, the two secondary windings 61 and 62 have the same structure, for example, the number of turns, the length of the wire, and the winding radius are the same.

[0098] Here, the planar transformer is described.

[0099] A planar transformer is a transformer that is assembled by printing a winding pattern on a printed circuit board and inserting it into a core. Since the winding pattern is printed on a planar transformer, there is an advantage that there is less deviation than, for example, a transformer that actually winds wires.

[0100] In addition, when actually winding the wire, there may be a tendency of deviation, but it is difficult to determine the tendency because the deviation occurs due to accidental factors (for example, the thickness of the wire, the batch, the operator, etc.). That is, in this case, the relationship (for example, the size relationship) between the L values ​​(inductance) of the two secondary windings is uncertain.

[0101] In contrast, generally speaking, in a planar transformer, a variation in design is likely to occur, but a variation in manufacturing is unlikely to occur.

[0102] Therefore, when a planar transformer is used, the relationship (for example, magnitude relationship) between the L values ​​(inductance) of the two secondary windings can be known in advance, and the L value (inductance) of one of the secondary windings is always larger.

[0103] exist Figure 2 In the structure shown, two secondary windings 61 and 62 are symmetrically formed with respect to one primary winding 14, and the structure is well balanced.

[0104] In addition, Figure 2 In the structure shown in the figure, since the position of the air gap H1 of the core J1 is offset, the secondary winding (in Figure 2 In the example of FIG. 2 , the secondary winding of the winding pattern 272 on the lower side has a tendency to have a higher inductance. That is, the L value of the secondary winding may be changed depending on the printing of the winding pattern and the position of the air gap.

[0105] For example, the relationship (eg, size relationship) between the L values ​​(inductances) of the two secondary windings may be changed by the position of the air gap H1 .

[0106] In this way, in a planar transformer, the deviation tends to be biased in one direction, so it is easy to control the deviation. Therefore, for example, the deviation can be confirmed in advance and the deviation of the duty ratio can be set in advance.

[0107] Such a control method is highly compatible with digital control. For example, the amount that causes the duty cycle to be unbalanced can be set to a fixed value, and the correction method (correction value, etc.) can be specified by a program. Thus, for example, there is no loss or cost caused by the deviation detection function, and there is no need to change the control of the correction method, and the advantage of improving the current imbalance can be enjoyed.

[0108] In addition, in a planar transformer, for example, it is possible to reduce the height, reduce the gap, and improve the power density.

[0109] Here, in this embodiment, the position of the air gap of the core is shown to be asymmetrical, but as another example, the position of the air gap of the core may be symmetrical. As a specific example, Figure 2 In the example shown in FIG. 1 , there is an air gap at the center in the vertical direction.

[0110] [Principle of Transformer]

[0111] Here, the principle of the transformer is explained.

[0112] In principle, the output of a transformer is determined by the turns ratio of the windings, and the characteristics change depending on the positional relationship of the windings, etc.

[0113] For example, the ratio of the voltage V1 of the primary winding to the voltage V2 of the secondary winding is equal to the ratio of the number of turns N1 of the primary winding to the number of turns N2 of the secondary winding (V2 / V1=N2 / N1).

[0114] The product of the voltage V1 and the current I1 of the primary winding is equal to the product of the voltage V2 and the current I2 of the secondary winding (I1×V1=I2×V2).

[0115] Thus, in a transformer, the output is determined by the turns ratio of the windings. This is also the case when multiple secondary windings are provided.

[0116] In addition, the output on the secondary side also changes depending on, for example, the positional relationship of the secondary winding with respect to the primary winding, the length of the electric wire, the winding radius, and the like.

[0117] In the case where a plurality of secondary windings are provided, basically, if the structure of these plurality of secondary windings is made unbalanced, disadvantages may occur.

[0118] Examples of such disadvantages include reduced efficiency, reduced element margin, deterioration of output ripple noise, changes in heat generation distribution, and increased costs for countermeasures against such disadvantages.

[0119] In addition, most existing transformers are made by manually winding wires. In this case, large structural deviations in winding resistance are likely to occur. Specifically, for example, the overlapping locations of wires and the gaps (intervals between wires) are often observed randomly, so the length of the wires and the winding positions cannot be managed, which becomes the main cause of the deviation.

[0120] <Duty ratio of two transistors>

[0121] Reference Figure 3 to Figure 5 , the duty ratio of the two transistors Q1 and Q2 is explained.

[0122] exist Figure 3 to Figure 5 In the graph shown in the example of , the horizontal axis represents time and the vertical axis represents the voltage level.

[0123] exist Figure 3 to Figure 5 In the example, the high level (in this embodiment, the level when turned on) and the low level (in this embodiment, the level when turned off) of the control voltages of the two transistors Q1 and Q2 are respectively set to be constant for explanation. For example, the high level can change according to the change of the on time.

[0124] Figure 3 This is a diagram showing an example of a control voltage when the high-side and low-side duty ratios are equal according to the embodiment.

[0125] exist Figure 3 In the example of FIG. 1 , the control voltage A1 is an example of a control voltage applied by the controller 111 as a gate-source voltage (Vgs) of the high-side transistor Q1 .

[0126] The control voltage A2 is an example of a control voltage applied by the controller 111 as a gate-source voltage (Vgs) of the low-side transistor Q2 .

[0127] exist Figure 3 In the example, control is performed in a manner that repeats the following states, namely, a state in which the high-side control voltage A1 and the low-side control voltage A2 are disconnected together (a specified low-level voltage), a state in which the high-side control voltage A1 is connected (a specified high-level voltage) and the low-side control voltage A2 is disconnected, a state in which the low-side control voltage A2 is connected and the high-side control voltage A1 is disconnected, and a state in which the high-side control voltage A1 and the low-side control voltage A2 are disconnected together.

[0128] Here, the period during which the high-side control voltage A1 is maintained on and the period during which the low-side control voltage A2 is maintained on are equal, for example, 400 [nsec]. In the present embodiment, such control voltages A1 and A2 can be controlled by the controller 111 .

[0129] Figure 4 1 is a diagram showing an example of a control voltage when the high side is corrected according to the embodiment. In this example, the duty ratio is different between the high side and the low side.

[0130] exist Figure 4 In the example of FIG. 1 , the control voltage A11 is an example of a control voltage applied by the controller 111 as a gate-source voltage (Vgs) of the high-side transistor Q1 .

[0131] The control voltage A12 is an example of a control voltage applied by the controller 111 as a gate-source voltage (Vgs) of the low-side transistor Q2 .

[0132] exist Figure 4 In the example, control is performed in a manner that repeats the following states, namely, a state in which the high-side control voltage A11 and the low-side control voltage A12 are disconnected together (a specified low-level voltage), a state in which the high-side control voltage A11 is connected (a specified high-level voltage) and the low-side control voltage A12 is disconnected, a state in which the low-side control voltage A12 is connected and the high-side control voltage A11 is disconnected, and a state in which the high-side control voltage A11 and the low-side control voltage A12 are disconnected together.

[0133] Here, the period during which the high-side control voltage A11 is maintained on and the period during which the low-side control voltage A12 is maintained on are different from each other, for example, 390 [nsec] and 400 [nsec], respectively.

[0134] In this embodiment, such control voltages A11 and A12 may be controlled by the controller 111 .

[0135] exist Figure 4 In the example, Figure 3 Compared with the example of FIG. 1 , the time T1 from when the high-side control voltage A11 drops to when the low-side control voltage A12 rises becomes longer.

[0136] Figure 5 1 is a diagram showing an example of control voltage when the high side and the low side are corrected according to the embodiment. In this example, the duty ratio is different between the high side and the low side.

[0137] exist Figure 5 In the example of FIG. 1 , the control voltage A21 is an example of a control voltage applied by the controller 111 as the gate-source voltage (Vgs) of the high-side transistor Q1 .

[0138] The control voltage A22 is an example of a control voltage applied by the controller 111 as a gate-source voltage (Vgs) of the low-side transistor Q2 .

[0139] exist Figure 5 In the example, control is performed in a manner that repeats the following states, namely, a state in which the high-side control voltage A21 and the low-side control voltage A22 are disconnected together (a specified low-level voltage), a state in which the high-side control voltage A21 is connected (a specified high-level voltage) and the low-side control voltage A22 is disconnected, a state in which the low-side control voltage A22 is connected and the high-side control voltage A21 is disconnected, and a state in which the high-side control voltage A21 and the low-side control voltage A22 are disconnected together.

[0140] Here, the period during which the high-side control voltage A21 is maintained on and the period during which the low-side control voltage A22 is maintained on are different from each other, for example, 390 [nsec] and 410 [nsec], respectively.

[0141] In this embodiment, such control voltages A21 and A22 may be controlled by the controller 111 .

[0142] exist Figure 5 In the example, Figure 4 Compared with the example of FIG. 1 , the time T11 from the high-side control voltage A21 falling to the low-side control voltage A22 rising is shortened, for example, to become Figure 3 Example of the situation at the same time.

[0143] Here, basically, in LLC converter, as Figure 3 As in the example of , the high-side switch and the low-side switch are alternately turned on with a duty ratio of 50:50.

[0144] On the other hand, in the present embodiment, such duty ratios are made unbalanced such as 49:51, thereby eliminating the imbalance of the currents flowing through the two secondary windings 61 and 62 .

[0145] For example, when the high-side switch and the low-side switch are turned on alternately for 400 [nsec] each with a duty ratio of 50:50, if the current in the secondary winding is observed, it is believed that more current flows during the period when the low side is turned on than during the period when the high side is turned on.

[0146] In order to resolve such a situation, in the present embodiment, control is performed that dares to destroy the duty ratio balance between the high side and the low side.

[0147] As a method of such control, for example, Figure 4 As in the example of the high side, only the on-time is shortened, or only the low side is extended, or Figure 5 In the example of FIG. 1 , the on-time of the low side and the on-time of the high side are adjusted simultaneously by increasing or decreasing. In these methods, for example, the same effect is obtained.

[0148] Here, the case where more current flows during the period when the low side is connected than during the period when the high side is connected is described, but conversely, in the case where more current flows during the period when the high side is connected than during the period when the low side is connected, it is also possible to use a method of shortening the connection time only on the low side, or a method of extending the connection time only on the high side, or a method of increasing or decreasing the connection time of the high side and the connection time of the low side at the same time.

[0149] As described above, in the present embodiment, in the case of the LLC converter (LLC resonant converter), correction is performed so as to shorten the ON width of the side with less current flowing on the high side and the low side.

[0150] Furthermore, strictly speaking, if only the on-time of one switch is shortened, a dead time change or a frequency change will occur. In order to avoid these changes, a method of increasing or decreasing the on-time of both switches may be used.

[0151] For example, in Figure 4 In the example of , only the high side shortens the on-time, and it can be seen that the dead time is extended. In this case, if the dead time is shortened accordingly, a change in period (≈ frequency) occurs.

[0152] In the following specific examples, for the sake of convenience, the case where the method of increasing and decreasing the on-time of two switches is used is described as an example.

[0153] <Balance of current flowing through two diodes>

[0154] Reference Figure 6A to Figure 6D , the balance of the current flowing in the two diodes will be described. Here, in this embodiment, the two diodes correspond to the two diodes D1 and D2.

[0155] exist Figure 6A to Figure 6D In the graph shown in the example of , the horizontal axis represents time and the vertical axis represents the current value.

[0156] Fig. 6A : is a diagram showing an example of current flowing in two switching elements of a comparative example. Here, in this embodiment, the two switching elements correspond to two transistors (transistors Q1 and Q2).

[0157] exist Fig. 6A , a current B1 flowing through the drain of one transistor and a current B2 flowing through the drain of another transistor are shown.

[0158] Figure 6B This is a diagram showing an example of current flowing through two diodes of a comparative example.

[0159] exist Figure 6B , a current C1 flowing through one diode and a current C2 flowing through another diode are shown.

[0160] exist Fig. 6A and Figure 6B In the example of FIG. 1 , the currents C1 and C2 flowing between the two diodes have different values, and thus become unbalanced.

[0161] In contrast, in this embodiment, the controller 111, such as Figure 5 As in the example of , control is performed to make the levels of the control voltages of the two transistors Q1 and Q2 different. By such control, in this embodiment, it is possible to suppress the imbalance of the values ​​of the currents flowing through the two diodes D1 and D2 and obtain a balance between them.

[0162] Figure 6C This is a diagram showing an example of current flowing through two switching elements (transistors Q1 and Q2 ) according to the embodiment.

[0163] exist Figure 6C , a current B11 flowing through the drain of one transistor Q1 and a current B12 flowing through the drain of the other transistor Q2 are shown.

[0164] Fig.6D This is a diagram showing an example of current flowing through two diodes D1 and D2 according to the embodiment.

[0165] exist Fig.6D , a current C11 flowing through one diode D1 and a current C12 flowing through another diode D2 are shown.

[0166] exist Figure 6C and Fig.6D In the example, the values ​​of the currents C11 and C12 flowing between the two diodes D1 and D2 are the same (or substantially the same).

[0167] [Load dependency]

[0168] Reference FIG. 7A to FIG. 7D , Figures 8A to 8D ,and FIG. 9A to FIG. 9D , the load dependency is described. In addition, in the present embodiment, when the load changes due to the frequency modulation method in the LLC converter, the frequency (switching frequency) may also change.

[0169] exist FIG. 7A to FIG. 7D , Figures 8A to 8D ,and FIG. 9A to FIG. 9D In the graph shown, the horizontal axis represents time and the vertical axis represents the current value.

[0170] <Example of the case where load current Io = 21 [A]>

[0171] Reference FIG. 7A to FIG. 7D , the case where the frequency (switching frequency) of the LLC converter is 1.2 [MHz], the output voltage Vo = 48 [V], and the load current Io = 21 [A] is described.

[0172] Fig. 7A 1 is a diagram showing an example of currents flowing through two switching elements of a comparative example when the load current Io is 21A.

[0173] Here, in the present embodiment, the two switching elements correspond to two transistors (transistors Q1 and Q2 ).

[0174] exist Fig. 7A , a current B101 flowing through the drain of one transistor and a current B102 flowing through the drain of another transistor are shown.

[0175] Figure 7B 1 is a diagram showing an example of currents flowing through two diodes of a comparative example when the load current Io is 21A.

[0176] Here, in the present embodiment, the two diodes correspond to the two diodes D1 and D2.

[0177] exist Figure 7B , a current C101 flowing through one diode and a current C102 flowing through another diode are shown.

[0178] exist Fig. 7A and Figure 7B In the example of FIG. 1 , the currents C101 and C102 flowing between the two diodes have different values, and thus become unbalanced.

[0179] Here, in Fig. 7A and Figure 7B In the example, Figure 3 As in the example, the length of the on-period (duty ratio) of the control voltages of the two transistors is the same.

[0180] In contrast, in this embodiment, the controller 111, such as Figure 5 As in the example of FIG. 1 , the lengths (duty ratios) of the on-times of the control voltages of the two transistors Q1 and Q2 are controlled to be different. By such control, in this embodiment, the imbalance of the current values ​​flowing through the two diodes D1 and D2 can be suppressed and their balance can be obtained.

[0181] Figure 7C This is a diagram showing an example of currents flowing through two switching elements (transistors Q1 and Q2 ) of the embodiment when the load current Io is 21A.

[0182] exist Figure 7C , a current B111 flowing through the drain of one transistor Q1 and a current B112 flowing through the drain of another transistor Q2 are shown.

[0183] Fig.7D 1 is a diagram showing an example of currents flowing through the two diodes D1 and D2 according to the embodiment when the load current Io is 21A.

[0184] exist Fig.7D , a current C111 flowing through one diode D1 and a current C112 flowing through another diode D2 are shown.

[0185] exist Figure 7C and Fig.7D In the example, the values ​​of currents C111 and C112 flowing between the two diodes D1 and D2 are the same (or substantially the same).

[0186] Here, in Figure 7C and Fig.7D In the example, the period during which the high-side control voltage is maintained on is set to -10 [nsec], that is, shortened by 10 [nsec], and the period during which the low-side control voltage is maintained on is set to +10 [nsec], that is, extended by 10 [nsec].

[0187] <Example of the case where load current Io = 10 [A]>

[0188] Reference Figures 8A to 8D , the case where the frequency (switching frequency) of the LLC converter is 1.25 [MHz], the output voltage Vo = 48 [V], and the load current Io = 10 [A] is described.

[0189] Fig. 8A 1 is a diagram showing an example of currents flowing through two switching elements of a comparative example when the load current Io is 10A.

[0190] Here, in the present embodiment, the two switching elements correspond to two transistors (transistors Q1 and Q2 ).

[0191] exist Fig. 8A , a current B121 flowing through the drain of one transistor and a current B122 flowing through the drain of another transistor are shown.

[0192] Figure 8B 1 is a diagram showing an example of currents flowing through two diodes of a comparative example when the load current Io is 10A.

[0193] Here, in the present embodiment, the two diodes correspond to the two diodes D1 and D2.

[0194] exist Figure 8B , a current C121 flowing through one diode and a current C122 flowing through another diode are shown.

[0195] exist Fig. 8A and Figure 8B In the example of FIG. 1 , the currents C121 and C122 flowing between the two diodes have different values, and thus become unbalanced.

[0196] Here, in Fig. 8A and Figure 8B In the example, Figure 3 As in the example, the length of the on-period (duty ratio) of the control voltages of the two transistors is the same.

[0197] In contrast, in this embodiment, the controller 111, such as Figure 5 As in the example of FIG. 1 , the lengths (duty ratios) of the on-times of the control voltages of the two transistors Q1 and Q2 are controlled to be different. By such control, in this embodiment, the imbalance of the current values ​​flowing through the two diodes D1 and D2 can be suppressed and their balance can be obtained.

[0198] Figure 8C This is a diagram showing an example of currents flowing through two switching elements (transistors Q1 and Q2 ) of the embodiment when the load current Io is 10A.

[0199] exist Figure 8C , a current B131 flowing through the drain of one transistor Q1 and a current B132 flowing through the drain of another transistor Q2 are shown.

[0200] Fig.8D 1 is a diagram showing an example of currents flowing through the two diodes D1 and D2 according to the embodiment when the load current Io is 10A.

[0201] exist Fig.8D , a current C131 flowing through one diode D1 and a current C132 flowing through another diode D2 are shown.

[0202] exist Figure 8C and Fig.8D In the example, the values ​​of currents C131 and C132 flowing between the two diodes D1 and D2 are the same (or substantially the same).

[0203] Here, in Figure 8C and Fig.8D In the example, the period during which the high-side control voltage is maintained on is set to -10 [nsec], that is, shortened by 10 [nsec], and the period during which the low-side control voltage is maintained on is set to +10 [nsec], that is, extended by 10 [nsec].

[0204] <Example of the case where load current Io=5[A]>

[0205] Reference FIG. 9A to FIG. 9D , the case where the frequency (switching frequency) of the LLC converter is 1.28 [MHz], the output voltage Vo = 48 [V], and the load current Io = 5 [A] is described.

[0206] Fig.9A 1 is a diagram showing an example of currents flowing through two switching elements of a comparative example when the load current Io is 5A.

[0207] Here, in the present embodiment, the two switching elements correspond to two transistors (transistors Q1 and Q2 ).

[0208] exist Fig.9A , a current B141 flowing through the drain of one transistor and a current B142 flowing through the drain of another transistor are shown.

[0209] Fig. 9B 1 is a diagram showing an example of currents flowing through two diodes of a comparative example when the load current Io is 5A.

[0210] Here, in the present embodiment, the two diodes correspond to the two diodes D1 and D2.

[0211] exist Fig. 9B , a current C141 flowing through one diode and a current C142 flowing through another diode are shown.

[0212] exist Fig.9A and Fig. 9B In the example of FIG. 1 , the values ​​of the currents C141 and C142 flowing between the two diodes are different, and thus the currents become unbalanced.

[0213] Here, in Fig.9A and Fig. 9B In the example, Figure 3 As in the example, the length of the on-period (duty ratio) of the control voltages of the two transistors is the same.

[0214] In contrast, in this embodiment, the controller 111, such as Figure 5 As in the example of FIG. 1 , the lengths (duty ratios) of the on-times of the control voltages of the two transistors Q1 and Q2 are controlled to be different. By such control, in this embodiment, the imbalance of the current values ​​flowing through the two diodes D1 and D2 can be suppressed and their balance can be obtained.

[0215] Fig. 9C This is a diagram showing an example of currents flowing through two switching elements (transistors Q1 and Q2 ) of the embodiment when the load current Io is 5 A.

[0216] exist Fig. 9C , a current B151 flowing through the drain of one transistor Q1 and a current B152 flowing through the drain of another transistor Q2 are shown.

[0217] Fig.9D1 is a diagram showing an example of currents flowing through the two diodes D1 and D2 according to the embodiment when the load current Io is 5A.

[0218] exist Fig.9D , a current C151 flowing through one diode D1 and a current C152 flowing through another diode D2 are shown.

[0219] exist Fig. 9C and Fig.9D In the example, the values ​​of currents C151 and C152 flowing between the two diodes D1 and D2 are the same (or substantially the same).

[0220] Here, in Fig. 9C and Fig.9D In the example, the period during which the high-side control voltage is maintained on is set to -10 [nsec], that is, shortened by 10 [nsec], and the period during which the low-side control voltage is maintained on is set to +10 [nsec], that is, extended by 10 [nsec].

[0221] In the above FIG. 7A to FIG. 7D , Figures 8A to 8D ,and FIG. 9A to FIG. 9D In the example of , even when the load changes, the correction method (correction amount of the on time) of the control voltage on the high side and the low side can be made the same, eliminating the current imbalance. That is, in this example, the correction method can be said to have no load dependence (or little load dependence), and a fixed correction can be applied to multiple loads.

[0222] Furthermore, as another example, control in which the correction method has load dependency may be performed.

[0223] [Input voltage dependence]

[0224] Reference FIG. 10A to FIG. 10J , the input voltage dependency is described. In addition, in the present embodiment, when the input voltage changes due to the frequency modulation method in the LLC converter, the frequency (switching frequency) may also change.

[0225] exist FIG. 10A to FIG. 10J In the graph shown, the horizontal axis represents time and the vertical axis represents the current value.

[0226] First, refer to Figures 10A to 10F , showing a case where the correction amount (correction amount of the duty ratio) of the on-off period of the control voltage of the two transistors Q1 and Q2 is fixed.

[0227] exist Figures 10A to 10FIn the example, the period during which the high-side control voltage is maintained on is set to -10 [nsec], that is, shortened by 10 [nsec], and the period during which the low-side control voltage is maintained on is set to +10 [nsec], that is, extended by 10 [nsec].

[0228] <Example of the case where the input voltage Vin=400 [V]>

[0229] Reference Figure 10A to Figure 10B , the case where the frequency (switching frequency) of the LLC converter is 1.2 [MHz] and the input voltage Vin = 400 [V] is described.

[0230] Fig. 10A This is a diagram showing an example of current flowing through two switching elements (transistors Q1 and Q2 ) of the embodiment when the input voltage Vin is 400 V and fixed correction is used.

[0231] exist Fig. 10A , a current B201 flowing through the drain of one transistor Q1 and a current B202 flowing through the drain of another transistor Q2 are shown.

[0232] Fig. 10B 1 is a diagram showing an example of currents flowing through two diodes D1 and D2 according to the embodiment when the input voltage Vin is 400 V and fixed correction is used.

[0233] exist Fig. 10B , a current C201 flowing through one diode D1 and a current C202 flowing through another diode D2 are shown.

[0234] exist Fig. 10A and Fig. 10B In the example, the values ​​of currents C201 and C202 flowing between the two diodes D1 and D2 are the same (or substantially the same).

[0235] <Example of the case where the input voltage Vin=350 [V]>

[0236] Reference FIG. 10C to FIG. 10D , the case where the frequency (switching frequency) of the LLC converter is 0.9 [MHz] and the input voltage Vin = 350 [V] is described.

[0237] Fig. 10C This is a diagram showing an example of current flowing through two switching elements (transistors Q1 and Q2 ) of the embodiment when the input voltage Vin is 350 V and fixed correction is used.

[0238] exist Fig. 10C, a current B211 flowing through the drain of one transistor Q1 and a current B212 flowing through the drain of another transistor Q2 are shown.

[0239] Fig. 10D This is a diagram showing an example of currents flowing through two diodes D1 and D2 according to the embodiment when the input voltage Vin is 350 V and fixed correction is used.

[0240] exist Fig. 10D , a current C211 flowing through one diode D1 and a current C212 flowing through another diode D2 are shown.

[0241] exist Fig. 10C and Fig. 10D In the example of , the values ​​of the currents C211 and C212 flowing between the two diodes D1 and D2 are different. Fig. 10C and Fig. 10D In the example, even if the control voltages of transistors Q1 and Q2 are Fig. 10A and Fig. 10B Even with the same correction as in the case of , the imbalance in the values ​​of the currents flowing through the two diodes D1 and D2 cannot be sufficiently suppressed.

[0242] <Example of the case where the input voltage Vin=300 [V]>

[0243] Reference Figure 10E to Figure 10F , the case where the frequency (switching frequency) of the LLC converter is 0.73 [MHz] and the input voltage Vin = 300 [V] is described.

[0244] Fig.10E This is a diagram showing an example of current flowing through two switching elements (transistors Q1 and Q2 ) of the embodiment when the input voltage Vin is 300 V and fixed correction is used.

[0245] exist Fig.10E , a current B221 flowing through the drain of one transistor Q1 and a current B222 flowing through the drain of another transistor Q2 are shown.

[0246] Fig.10F 1 is a diagram showing an example of currents flowing through two diodes D1 and D2 according to the embodiment when the input voltage Vin is 300 V and fixed correction is used.

[0247] exist Fig.10F , a current C221 flowing through one diode D1 and a current C222 flowing through another diode D2 are shown.

[0248] exist Fig.10E and Fig.10FIn the example of , the values ​​of the currents C221 and C222 flowing between the two diodes D1 and D2 are different. Fig.10E and Fig.10F In the example, even if the control voltages of transistors Q1 and Q2 are Fig. 10A and Fig. 10B Even with the same correction as in the case of , the imbalance in the values ​​of the currents flowing through the two diodes D1 and D2 cannot be sufficiently suppressed.

[0249] Here, in Fig. 10C and Fig. 10D Examples, and Fig.10E and Fig.10F In the example, for Fig. 10A and Fig. 10B Compared with the example of , the case where the correction amount (correction amount of the duty ratio) during the on and off periods of the control voltages of the two transistors Q1 and Q2 is fixed and made the same (the case of fixed correction) is described.

[0250] In contrast, the case where the correction amount (duty ratio correction amount) of the on-off period of the control voltage of the two transistors Q1 and Q2 is changed according to the input voltage (variable correction case) is described. In this embodiment, the controller 111 can suppress the imbalance of the value of the current flowing through the two diodes D1 and D2 through such control and obtain their balance.

[0251] <Example of the case where the input voltage Vin=350 [V]>

[0252] Reference Figure 10G to Figure 10H , the case where the frequency (switching frequency) of the LLC converter is 0.9 [MHz] and the input voltage Vin = 350 [V] is described.

[0253] Figure 10G This is a diagram showing an example of current flowing through two switching elements (transistors Q1 and Q2 ) of the embodiment when the input voltage Vin is 350 V and variable correction is used.

[0254] exist Figure 10G , a current B301 flowing through the drain of one transistor Q1 and a current B302 flowing through the drain of another transistor Q2 are shown.

[0255] Fig. 10H This is a diagram showing an example of currents flowing through two diodes D1 and D2 according to the embodiment when the input voltage Vin is 350 V and variable correction is used.

[0256] exist Fig. 10H, a current C301 flowing through one diode D1 and a current C302 flowing through another diode D2 are shown.

[0257] exist Figure 10G and Fig. 10H In the example, the values ​​of currents C301 and C302 flowing between the two diodes D1 and D2 are the same (or substantially the same).

[0258] Here, in Figure 10G and Fig. 10H In the example, the period during which the high-side control voltage is maintained on is set to -20 [nsec], that is, shortened by 20 [nsec], and the period during which the low-side control voltage is maintained on is set to +20 [nsec], that is, extended by 20 [nsec].

[0259] <Example of the case where the input voltage Vin=300 [V]>

[0260] Reference Figure 10I to Figure 10J , the case where the frequency (switching frequency) of the LLC converter is 0.73 [MHz] and the input voltage Vin = 300 [V] is described.

[0261] Fig.10I This is a diagram showing an example of current flowing through two switching elements (transistors Q1 and Q2 ) of the embodiment when the input voltage Vin is 300 V and variable correction is used.

[0262] exist Fig.10I , a current B311 flowing through the drain of one transistor Q1 and a current B312 flowing through the drain of another transistor Q2 are shown.

[0263] Fig.10J This is a diagram showing an example of currents flowing through two diodes D1 and D2 according to the embodiment when the input voltage Vin is 300 V and variable correction is used.

[0264] exist Fig.10J , a current C311 flowing through one diode D1 and a current C312 flowing through another diode D2 are shown.

[0265] exist Fig.10I and Fig.10J In the example, the values ​​of currents C311 and C312 flowing between the two diodes D1 and D2 are the same (or substantially the same).

[0266] Here, in Fig.10I and Fig.10JIn the example, the period during which the high-side control voltage is maintained on is set to -25 [nsec], that is, shortened by 25 [nsec], and the period during which the low-side control voltage is maintained on is set to +25 [nsec], that is, extended by 25 [nsec].

[0267] In the above FIG. 10A to FIG. 10J In the example of , when the input voltage changes, the current imbalance can be eliminated by changing the correction method of the control voltage on the high side and the low side (correction amount of the on time). That is, in this example, the correction method can be said to be input voltage dependent, and variable correction can be applied to multiple input voltages.

[0268] Furthermore, as another example, control in which the correction method has no input voltage dependency may be performed.

[0269] [Control of fixed correction and variable correction by controller]

[0270] <Fixed Fixes>

[0271] In the fixed correction, the controller 111 sets the correction amount of the on-off period of the control voltage of the two transistors Q1 and Q2 (correction amount of the duty ratio) to be always the same, and performs on-off control of the control voltage.

[0272] In addition, the correction amount may be set in advance when the switching power supply device 1 is shipped, or may be fixed after the product is shipped.

[0273] <Variable correction>

[0274] In the variable correction, the controller 111 changes the correction amount of the on-off period of the control voltage of the two transistors Q1 and Q2 (correction amount of the duty ratio) according to a predetermined index value, and performs on-off control of the control voltage.

[0275] In addition, the correspondence relationship between the index value and the correction amount may be preset when the switching power supply device 1 is shipped, or may be fixed after the product is shipped.

[0276] Such a correspondence relationship may also be stored in the memory 131 of the controller 111, for example.

[0277] Here, various values ​​may be used as the index value, for example, input voltage, frequency (switching frequency), load, etc. may be used.

[0278] As the index value, for example, when the index value changes, if it is fixed at the same correction value, an index value that cannot sufficiently suppress the imbalance of the values ​​of the currents flowing through the two diodes D1 and D2 may be used.

[0279] The controller 111 has a function of acquiring a predetermined index value.

[0280] As an example, when the value set by the controller 111 itself (the controller 111) is used as the index value, the controller 111 acquires the value.

[0281] As another example, the controller 111 may acquire the result of detecting a predetermined index value by itself (controller 111) or an external circuit. Here, the circuit for detecting the index value may be configured arbitrarily.

[0282] The controller 111 obtains the correction amount corresponding to the obtained index value based on the correspondence between the index value and the correction amount. The controller 111 corrects the on-off period of the control voltage of the two transistors Q1 and Q2 from the reference value using the obtained correction amount, and performs on-off control of the control voltage.

[0283] For example, Figure 3 As shown, the reference value is a value when the on and off periods of the two transistors Q1 and Q2 are the same, but values ​​in other cases may also be used.

[0284] <Variable correction table>

[0285] Fig.11 This is a diagram showing an example of the variable correction table 1011 according to the embodiment.

[0286] The variable correction table 1011 is an example of the correspondence relationship between the index value and the correction amount.

[0287] exist Fig.11 In the example, frequency is used as the indicator value.

[0288] In addition, the variable correction table 1011 may be called a map instead of a table, for example.

[0289] The variable correction table 1011 stores the relationship between the frequency (switching frequency) corresponding to the index value and the adjustment width (high-side on-time correction width) corresponding to the correction amount. Fig.11 In the example of , the frequency corresponding to the index value is specified using the frequency width.

[0290] Specifically, when the frequency is 500 to 700 kHz, the adjustment amplitude is -10 [nsec], when the frequency is 701 to 1000 kHz, the adjustment amplitude is -5 [nsec], when the wave number is 1001 to 1500 kHz, the adjustment amplitude is -2 [nsec], and when the frequency is 1501 to 2000 kHz, the adjustment amplitude is 0 [nsec].

[0291] Here, the adjustment width of -10 [nsec] means that the on-time of the high side is shortened by 10 [nsec], and the same applies to other adjustment widths.

[0292] Furthermore, the plurality of adjustment ranges may also include a case where no adjustment (correction) is performed. Fig.11 In the example, an adjustment width of 0 [nsec] means that no adjustment (correction) is performed on the reference value.

[0293] Here, use Fig.11 The structure in which the table (map) shown above is variably corrected is suitable for combination with a structure using digital control (digital controller), for example.

[0294] Generally, LLC converters perform output control by frequency modulation. Therefore, for example, by storing a correction table (e.g., duty cycle unevenness map) in the controller according to conditions such as frequency, output voltage, or load, a more detailed balance improvement effect can be obtained.

[0295] As described above, in the switching power supply device 1 of the present embodiment, the coupling coefficients of the two secondary windings 61 and 62 of the transformer Tr1 with respect to the primary winding 14 can be made equal, and the current imbalance can be eliminated.

[0296] The switching power supply device 1 of the present embodiment can achieve various advantages such as improving current imbalance caused by variation in secondary-side inductance of the transformer Tr1 , balancing energy output from the secondary windings 61 and 62 , improving efficiency, and enhancing performance.

[0297] In the switching power supply device 1 of the present embodiment, by using different on-times for the bridges on the primary side, current balance can be achieved in the secondary windings 61 and 62 of the center-tapped structure on the secondary side.

[0298] In the switching power supply device 1 of the present embodiment, for example, by performing fixed correction or variable correction control to make the duty ratios of the two transistors Q1 and Q2 unbalanced in a predetermined manner, it is possible to eliminate the need for additional circuits and other controls.

[0299] Here, in this embodiment, the problem caused in the structure of the transformer is solved by a control method.

[0300] Furthermore, in the present embodiment, the problems occurring in the structure of the transformer are solved while suppressing the cost and the labor.

[0301] Here, in the present embodiment, a structure in which two windings (secondary windings) are arranged on the secondary side relative to one winding (primary winding) on ​​the primary side is shown, but as another example, a structure in which three or more windings (secondary windings) are arranged on the secondary side relative to one winding (primary winding) on ​​the primary side may also be used.

[0302] In addition, the number of turns of the multiple secondary windings may also be the same.

[0303] In addition, in this embodiment, the Figure 5 As an example, the structure of controlling the on-time of both the high side and the low side is as follows, but as another example, it is also possible to Figure 4 As in the example of , a structure for controlling the on period of either the high side or the low side is used.

[0304] In addition, in this embodiment, the Figure 5 As in the example of FIG. 1 , a control structure that takes the dead time into consideration is performed. However, as another example, Figure 4 As in the example of , a structure is used to perform control without considering the dead time.

[0305] In addition, in this embodiment, a structure in which a half-bridge circuit (a circuit using two transistors Q1 and Q2) is provided on the primary side of the switching power supply device 1 is shown, but as another example, a structure in which a full-bridge circuit (for example, four transistors) is provided may also be used.

[0306] In addition, in the present embodiment, a configuration in which a center tap method is used on the secondary side of the switching power supply device 1 is shown, but as another example, a configuration other than the center tap method may be used.

[0307] In the present embodiment, for example, correction may be performed by digital control, or correction may be performed by analog control.

[0308] In addition, in the present embodiment, for example, the number of legs of the transformer may be arbitrary, and three legs, four legs, or five legs may be used.

[0309] Here, the leg is a core portion, indicating a portion that passes through the substrate.

[0310] In addition, as for setting the resonant inductance, for example, there are a case where an external inductor is used and a case where a small leakage inductance is utilized.

[0311] For example, in the switching power supply device 1 of the present embodiment, the resonant inductor and the transformer are integrated into one structure, and an external inductor is basically unnecessary.

[0312] In addition, a program for realizing the functions of any structural part (for example, controller 111) of any device described above can also be recorded in a computer-readable storage medium, and the program can be read into a computer system and executed. In addition, the "computer system" mentioned here includes hardware such as an operating system or peripheral devices. In addition, "computer-readable storage medium" refers to a storage device such as a removable medium such as a floppy disk, a magneto-optical disk, a ROM, a CD (Compact Disc)-ROM (Read Only Memory), and a hard disk built into the computer system. Moreover, "computer-readable storage medium" also includes a storage medium that keeps the program for a certain period of time, such as a volatile memory inside a computer system of a server or client in the case of sending a program via a network such as the Internet or a communication line such as a telephone line. The volatile memory can also be, for example, a RAM (Random Access Memory). The storage medium can also be, for example, a non-temporary storage medium.

[0313] In addition, the above-mentioned program can also be transmitted from a computer system storing the program in a storage device, etc., to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the "transmission medium" for transmitting the program refers to a medium having the function of transmitting information, such as a network such as the Internet or a communication line such as a telephone line.

[0314] In addition, the above-mentioned program may also be a program for realizing a part of the above-mentioned functions. Moreover, the above-mentioned program may also be so-called differential software that realizes the above-mentioned functions by combining with a program already stored in the computer system. Differential software may also be called differential program.

[0315] In addition, the functions of any structural parts (for example, controller 111) of any device described above can also be implemented by a processor. For example, each process of the embodiment can also be implemented by a processor that acts based on information such as a program and a computer-readable storage medium that stores information such as a program. Here, in the processor, for example, the functions of each part can also be implemented by individual hardware, or the functions of each part can also be implemented by integrated hardware. For example, it is also possible that the processor includes hardware, and the hardware includes at least one of a circuit for processing digital signals and a circuit for processing analog signals. For example, the processor can also be composed of one or more circuit devices mounted on a circuit substrate, or one or both of one or more circuit elements. As a circuit device, an IC (Integrated Circuit) or the like can also be used, and as a circuit element, a resistor or a capacitor or the like can also be used.

[0316] Here, the processor may be, for example, a CPU. However, the processor is not limited to the CPU, and various processors such as a GPU (Graphics Processing Unit) or a DSP (Digital Signal Processor) may also be used. In addition, the processor may be, for example, a hardware circuit based on an ASIC (Application Specific Integrated Circuit). In addition, the processor may be, for example, composed of a plurality of CPUs, or may be composed of a hardware circuit based on a plurality of ASICs. In addition, the processor may be, for example, composed of a combination of a plurality of CPUs and a hardware circuit based on a plurality of ASICs. In addition, the processor may include, for example, one or more of an amplifier circuit or a filter circuit for processing analog signals.

[0317] As mentioned above, although the embodiment of this disclosure is described in detail with reference to the drawings, the specific structure is not limited to this embodiment, and also includes the design etc. within the scope which does not deviate from the summary of this disclosure.

[0318] [Configuration Example 1] to [Configuration Example 4] are shown below.

[0319] [Structural Example 1]

[0320] A switching power supply device, wherein:

[0321] Equipped with: Planar transformer,

[0322] The primary side of the transformer includes: a bridge having a plurality of switching elements connected in series, and a primary winding.

[0323] The switching element includes: the switching element controlled with a first on-time, and the switching element controlled with a second on-time different from the first on-time.

[0324] [Structural Example 2]

[0325] The switching power supply device according to [Configuration Example 1], wherein:

[0326] On the secondary side of the transformer, there are two secondary windings with a center-tapped structure.

[0327] [Structural Example 3]

[0328] The switching power supply device according to [Configuration Example 1] or [Configuration Example 2], wherein:

[0329] The transformer has an air gap located at an asymmetrical position.

[0330] [Structural Example 4]

[0331] A switching power supply device according to any one of [Configuration Example 1] to [Configuration Example 3], wherein:

[0332] Based on the correspondence between the first on-time and the second on-time and a predetermined index value, the first on-time and the second on-time are set according to the index value.

Claims

1. A switching power supply device, wherein: Equipped with: Planar transformer, The primary side of the transformer includes: a bridge having a plurality of switching elements connected in series, and a primary winding. The switching element includes: the switching element controlled with a first on-time, and the switching element controlled with a second on-time different from the first on-time.

2. The switching power supply device according to claim 1, wherein: On the secondary side of the transformer, there are two secondary windings with a center-tapped structure.

3. The switching power supply device according to claim 1 or 2, wherein: The transformer has an air gap located at an asymmetrical position.

4. The switching power supply device according to claim 1 or 2, wherein: Based on the correspondence between the first on-time and the second on-time and a predetermined index value, the first on-time and the second on-time are set according to the index value.

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