Power converter, multi-leg transformer, charger, and vehicle

Abstract

To provide a power converter capable of downsizing magnetic components with which a plurality of LLC resonant converters are provided, respectively.SOLUTION: A power converter comprises the N number of LLC circuits provided with transformers, respectively (where N is a natural number of 2 or more). The transformers of the N number of LLC circuits are integrated into a multi-leg transformer 30 where middle legs 43 each provided with a gap are arranged in a matrix-shape in X-direction and Z-direction. According to the multi-leg transformer 30, primary wirings Pan and primary wirings Pbn of the transformers are wound around the respective middle legs 43 adjacent to each other in a column direction in such a manner that directions of generated magnetic fluxes are made to be opposite to each other.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a power converter that converts a DC voltage into a desired output voltage. [Background technology]

[0002] There is a demand for higher power output from charging devices that charge storage batteries mounted on electric vehicles, etc. A known power converter that achieves this is a multiphase power converter that drives LLC resonant converters with a number of phases (number of operating phases) with a phase shift (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6696617 Summary of the Invention [Problem to be solved by the invention]

[0004] LLC resonant converters have magnetic components such as resonant inductors and transformers, which have larger loss and occupancy rates than other components, hindering the miniaturization of power converters equipped with multiple LLC resonant converters.

[0005] One aspect of the present invention is to provide a power converter, a multi-leg transformer, a charging device, and a vehicle that can reduce the size of magnetic components included in each of a plurality of LLC resonant converters. [Means for solving the problem]

[0006] A power converter according to one aspect of the present invention includes N LLC resonant converters (N is a natural number equal to or greater than 2) each having a transformer. The transformers of the N LLC resonant converters are integrated into a multi-leg transformer in which center legs having gaps are arranged in a matrix in the row and column directions. In the multi-leg transformer, primary windings of the transformer are wound on center legs adjacent to each other in at least one of the row and column directions so that the directions of the generated magnetic flux are opposite to each other. A power converter according to one embodiment of the present invention includes N LLC resonant converters (N is a natural number equal to or greater than 2) each having a transformer. The transformers of the N LLC resonant converters are integrated into a multi-legged transformer in which center legs having gaps are arranged in a matrix in the row and column directions. The transformer includes a first primary winding and a second primary winding connected in series. In the multi-legged transformer, adjacent center legs in the column direction are wound such that the magnetic flux generated by the first primary winding and the second primary winding have opposite directions. A multi-leg transformer according to one embodiment of the present invention has gapped center legs arranged in a matrix in the row and column directions. The multi-leg transformer integrates the transformers of N LLC resonant converters (N is a natural number of 2 or greater). Primary windings of the transformers are wound around adjacent center legs in at least either the row or column direction so that the directions of the generated magnetic flux are opposite. [Effects of the Invention]

[0007] According to one aspect of the present invention, the transformers provided in each of multiple LLC resonant converters can be integrated into a multi-legged transformer, and the large leakage inductance of the multi-legged transformer can be used as a resonant inductor, thereby making it possible to miniaturize the magnetic components provided in each of the multiple LLC resonant converters. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 10 is a diagram illustrating an example of use of a power converter as a charging device. [Figure 2] FIG. 1 is a diagram illustrating a configuration example of a power converter. [Figure 3]FIG. 4 is a diagram illustrating a drive signal output by a control unit. [Figure 4] FIG. 1 is a diagram illustrating a configuration example of a full-bridge circuit compatible with HVDC input. [Figure 5] 1A and 1B are diagrams illustrating an example of the configuration of a magnetic core of a multi-leg transformer. [Figure 6] FIG. 1 is a diagram showing a winding arrangement of a multi-leg transformer. [Figure 7] FIG. 1 is a simplified circuit diagram of a multi-leg transformer. [Figure 8] 10A and 10B are diagrams illustrating the operation of a multi-leg transformer. [Figure 9] FIG. 10 is a diagram illustrating another example of the configuration of a power converter. [Figure 10] FIG. 10 is a diagram illustrating another example of the configuration of a power converter. [Figure 11] FIG. 10 is a diagram illustrating another example of the configuration of a power converter. [Figure 12] 12A and 12B are diagrams illustrating the iron loss reduction effect of the multi-leg transformer shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following embodiments, components having similar functions will be given the same reference numerals and descriptions thereof will be omitted as appropriate.

[0010] Referring to FIG. 1, a power converter 1 according to this embodiment is used as a charging device for charging a storage battery 3 (battery) mounted on a vehicle 2 such as an electric car.

[0011] 1(a), when the power supplied to the vehicle 2 from outside the vehicle is an alternating current (AC) voltage such as a commercial power supply, the power converter 1 is mounted on the vehicle 2 together with a power factor correction (PFC) circuit 4. The PFC 4 converts the AC voltage supplied to the vehicle 2 into a direct current (DC) voltage, and the power converter 1 converts the DC voltage converted by the PFC 4 into a desired output voltage to charge the storage battery 3.

[0012] 1(b), when the power supplied from outside the vehicle to the vehicle 2 is a DC voltage, the power converter 1 is installed in a facility outside the vehicle 2, such as a charging station, together with a power factor correction (PFC) circuit 4. The PFC 4 converts the AC voltage supplied from a commercial power source or the like into a direct current (DC) voltage, and the power converter 1 converts the DC voltage converted by the PFC 4 into a desired DC voltage and supplies it to the vehicle 2 to charge the storage battery 3.

[0013] Referring to FIG. 2, the power converter 1 is an N-phase multiphase LLC resonant converter. N is a natural number equal to or greater than 2, and FIG. 2 shows an example where N=3. The power converter 1 is made up of N full-bridge LLC resonant converters (hereinafter referred to as LLC circuits 10) whose input and output sides are connected in parallel and which operate in N-phase multiphase with a phase difference of 360° / N. n The subscript n indicates the number of phases (1 to N).

[0014] LLC circuit 10 n The inverter includes a full-bridge circuit 11. The full-bridge circuit 11 has a first switching leg (upper switching element QH1 and lower switching element QL1) and a second switching leg (upper switching element QH2 and lower switching element QL2) connected in parallel between the positive and negative poles of a DC voltage Vin. In the following description, when there is no distinction to be made based on the number of phases or the switching legs, the subscripts will be omitted as appropriate.

[0015] The upper switch element QH and the lower switch element QL are configured, for example, by field-effect transistors (MOSFETs: metal-oxide-semiconductor field-effect transistors). The upper switch element QH and the lower switch element QL have a body diode between the source and drain. The upper switch element QH and the lower switch element QL may be switching elements such as IGBTs (insulated gate bipolar transistors), GaN devices, and SiC (silicon carbide) devices.

[0016] The upper switch element QH connected to the positive terminal of the DC voltage Vin is the upper arm of the switching leg, and the lower switch element QL connected to the negative terminal of the DC voltage Vin is the lower arm of the switching leg.

[0017] LLC circuit 10 n are the resonant inductors Lra and Lrb and the transformer T n and resonance capacitors Cr, Cra, and Crb. n is the primary winding Pa connected in series through the resonant capacitor Cr. n , Pb n and the secondary winding Sa connected in series n , Sb n And, it is equipped with.

[0018] The resonant inductor Lra has one end connected to the output point of the first switching leg (the connection point between the upper switch element QH1 and the lower switch element QL1) and the other end connected to the primary winding Pa. n The resonant inductor Lrb has one end connected to the output point of the second switching leg (the connection point between the upper switch element QH2 and the lower switch element QL2) and the other end connected to the primary winding Pb n The primary winding Pa is connected to one end of the n The other end of the primary winding Pb n The other end of the resistor 11 is connected to the other end of the resistor 11 via a resonant capacitor Cr.

[0019] Primary winding Pa n The connection point between the primary winding Pb and the resonant capacitor Cr is connected to the first neutral point A via the inter-phase resonant capacitor Cra. n The connection point between the resonant capacitor Cr and the phase-to-phase resonant capacitor Crb is connected to the second neutral point B. n via the first neutral point A and the second neutral point B, the power converter 1 can balance the current between the phases.

[0020] When the inductance of the resonant inductors Lra and Lrb is Lr, the capacitance of the resonant capacitor Cr is Cr0, and the capacitance of the resonant capacitors Cra and Crb is Cr1, the resonant frequency f is calculated by the following equation (1).

[0021]

number

[0022] LLC circuit 10 n is a transformer T n Secondary winding Sa n , Sb n The rectifying and smoothing circuit 12 is connected to the secondary winding Sa. n , Sb n The AC current output from the output terminal is rectified by an output capacitor to output an output voltage Vo. The rectifying and smoothing circuit 12 can employ a circuit method such as center tap rectification, bridge rectification, voltage doubler rectification, or Cock-Walton rectification. The rectifying and smoothing circuit 12 can also employ synchronous rectification using FETs instead of diodes.

[0023] The control unit 20 is a semiconductor device integrated on a substrate. As shown in FIG. 3, the control unit 20 generates a driving signal G having a phase difference of 120 degrees between the first, second, and third phases. n1 , G n2 Generates and outputs the drive signal G n1 is the upper switch element QH of the first switching leg. n1 and lower switch element QL n1 The drive signal G is a pulse signal (gate signal) with a duty of 50%. n2 is the upper switch element QH of the second switching leg. n2 and lower switch element QL n2 A drive signal G n1 The upper switch element QH of the first switching leg is a complementary pulse signal (gate signal) with a duty cycle of 50% and an inverted polarity. n1 and the lower switch element QL of the second switching leg n2 and the lower switching element QL of the first switching legn1 and the upper switch element QH of the second switching leg n2 The two operate complementary with a duty of 50%.

[0024] The control unit 20 controls the frequency of the drive signal G n1 , G n2 By increasing the switching frequency, the output voltage Vo is decreased, and by decreasing the switching frequency, the output voltage Vo is increased.

[0025] LLC circuit 10 n The full-bridge circuit 11 may be a full-bridge circuit 11a compatible with HVDC (High Voltage Direct Current) input, as shown in Fig. 4. The full-bridge circuit 11a is a full-bridge LLC resonant converter in which a first switching leg (upper switch element QH1 and lower switch element QL1) and a second switching leg (upper switch element QH2 and lower switch element QL2) are connected in series. Capacitors Cin1 and Cin2 are connected in series between the positive and negative poles of a DC voltage Vin. The first switching leg is connected in parallel with capacitor Cin1, and the second switching leg is connected in parallel with capacitor Cin2.

[0026] The first to third phase transformers T1 to T3 are integrated as a multi-leg transformer 30. The multi-leg transformer 30 can be configured as a planar transformer. The multi-leg transformer 30 includes a magnetic core 40 shown in FIG. 5(a). The magnetic core 40 includes a pair of bases 41, two outer legs 42, and six center legs 43. The pair of bases 41 are substantially rectangular plate-like bodies, and are arranged opposite each other with a gap in the Y direction by the two outer legs 42. The two outer legs 42 are gapless leg cores, and are arranged on both sides in the X direction, which is perpendicular to the Y direction. The six center legs 43 are leg cores with gaps (GAPs), and are arranged in a 3-row x 2-column matrix, with three in the X direction (row direction) and two in the Z direction (column direction), which is perpendicular to the X and Y directions.

[0027] Referring to FIG. 6(a), the three center legs 43 in the first row arranged in the X direction are provided with the primary windings Pa of the first to third phases. n and secondary winding Sa n Similarly, the three center legs 43 in the second row arranged in the X direction are wound with the primary windings Pb n and secondary winding Sb n Referring to FIG. 6(b), the two center legs 43 arranged in the Z direction are wound with the primary winding Pa of the same phase. n and secondary winding Sa n and primary winding Pb n and secondary winding Sb n The two are wound so that the directions of the magnetic flux are opposite.

[0028] The center leg 43 has a gap with a magnetic permeability of approximately 1, and therefore has a magnetic permeability several hundred to several thousand times greater than that of the base 41 and the outer legs 42. Since magnetic reluctance is the reciprocal of magnetic permeability, the center leg 43 has an extremely large magnetic reluctance Rmg compared to the base 41 and the outer legs 42. Therefore, the multi-leg transformer 30 can be simplified into a circuit having an electromotive force and magnetic reluctance Rmg, as shown in FIG.

[0029] If the magnetic fluxes generated in the primary windings Pa1 to Pa3 are Φa1 to Φa3 and the magnetic fluxes generated in the primary windings Pb1 to Pb3 are Φb1 to Φb3, Φa1 to Φa3 and Φb1 to Φb3 do not interfere with each other because the magnetic resistance Rmg of the center leg 43 is high. Φa1 to Φa3 and Φb1 to Φb3 pass through the base 41 and outer leg 42, which have low magnetic resistance, as magnetic paths, as shown in Figure 7. Because the magnetic fluxes generated in the first row Φa1 to Φa3 and the second row Φb1 to Φb3 are opposite in direction, Φa1 to Φa3 and Φb1 to Φb3 are canceled out by the two outer legs 42 with no gap and the upper and lower bases 41, reducing core loss.

[0030] 8(a) and 8(b) show the current path in the LLC circuit 101 and the flow of magnetic flux in the multi-leg transformer 30 when the upper switch element QH1 of the first switching leg and the lower switch element QL2 of the second switching leg are turned on. The windings through which current flows are the primary windings Pa1 and Pb1 and the secondary winding Sa1. The primary winding Pa1 and the secondary winding Sa1 are wound around the same center leg 43 and are tightly coupled. The primary winding Pb1 and the secondary winding Sa1, and the primary winding Pa1 and the primary winding Pb1, which are wound around different center legs 43, are tightly coupled. 、 The multi-leg transformer 30 is loosely coupled and has a large leakage inductance.

[0031] 8(c) and (d) show the current path in the LLC circuit 101 and the flow of magnetic flux in the multi-leg transformer 30 when the lower switch element QL1 of the first switching leg and the upper switch element QH2 of the second switching leg are turned on. The windings through which current flows are the primary windings Pa1 and Pb1 and the secondary winding Sb1. The primary winding Pb1 and the secondary winding Sba1 are wound on the same center leg 43 and are tightly coupled. The primary winding Pa1 and the secondary winding Sb1, and the primary winding Pa1 and the primary winding Pb1, which are wound on different center legs 43, are tightly coupled. 、 The multi-leg transformer 30 is loosely coupled and has a large leakage inductance.

[0032] The leakage inductance of the multi-leg transformer 30 can be used as the inductance of the resonant inductors Lra and Lrb, making it possible to reduce the number of parts.

[0033] The multi-leg transformer 30 can also be applied to a power converter 1a configured with N half-bridge LLC resonant converters (hereinafter referred to as LLC circuits 50n) as shown in Fig. 9. Fig. 9 shows an example where N=3. The control unit 20a controls N LLC circuits 50n in a multiphase configuration with N phases having a phase difference of 360° / N. n Activate the.

[0034] LLC circuit 50 nThe inverter includes a half-bridge circuit 51. In the half-bridge circuit 51, an upper switch element QH1 and a lower switch element QL1 are connected between the positive and negative poles of a DC voltage Vin.

[0035] LLC circuit 50 n are the resonant inductors Lra and Lrb and the transformer T n and resonance capacitors Cr, Cra, and Crb. n is the primary winding Pa connected in series n , Pb n Equipped with.

[0036] One end of the multi-leg transformer 30 is connected to the output point of the half-bridge circuit 51 (the connection point between the upper switch element QH1 and the lower switch element QL1). n One end of the primary winding Pa is connected to n The other end of the primary winding Pb is connected so that the direction of the generated magnetic flux is reversed. n It is connected to one end of the primary winding Pb n The other end of each of the resonant inductors Lra and Lrb is connected to the negative pole of the DC voltage Vin. This allows the resonant inductors Lra and Lrb shown in Fig. 9 to use the leakage inductance of the multi-leg transformer 30, thereby reducing the number of components.

[0037] FIG. 10(a) shows a configuration of N half-bridge LLC resonant converters (hereinafter referred to as LLC circuits 50a n FIG. 10 shows an example where N=2. The control unit 20b controls N LLC circuits 50a in a multiphase configuration with N phases having a phase difference of 360° / N. n Activate the.

[0038] LLC circuit 50 n is the resonant inductor Lra and the transformer T n and resonance capacitors Cr and Cra. n is the primary winding Pa n and secondary winding Sa nThe first-phase and second-phase transformers T1 and T2 are integrated as a multi-leg transformer 30a. The multi-leg transformer 30a can be configured as a planar transformer. The multi-leg transformer 30a includes a magnetic core 40a shown in FIG. 10(b). The magnetic core 40a includes a pair of bases 41 and two center legs 43. The pair of bases 41 are substantially rectangular plate-like bodies and are arranged opposite to each other with a gap in the Y direction. The two center legs 43 are leg cores with a gap (GAP) and are arranged in a 1 row x 2 column matrix, with one in the X direction and two in the Z direction perpendicular to the X and Y directions. A primary winding Pa1 and a secondary winding Sa1, and a primary winding Pa2 and a secondary winding Sa2 of the same phase are wound around the two center legs 43 arranged in the Z direction, respectively, so that the directions of magnetic flux generation are opposite to each other. The leakage inductance of the multi-leg transformer 30a can be used as the inductance of the resonant inductor Lra, making it possible to reduce the number of parts.

[0039] FIG. 11(a) shows an N-stage full-bridge LLC resonant converter (hereinafter referred to as LLC circuit 10 n The power converter 1c is a power converter 1c configured with a control unit 20c and an N-stage LLC circuit 10. N is a natural number equal to or greater than 2, and FIG. 11 shows an example where N=2. The power converter 1c is a power converter 1c configured with a control unit 20c and an N-stage LLC circuit 10. n are operated in synchronization with the same drive signals G1 and G2.

[0040] The first-stage transformer T1 and the second-stage transformer T2 are integrated into a multi-leg transformer 30b. The multi-leg transformer 30b can be configured as a planar transformer. The multi-leg transformer 30b includes a magnetic core 40b shown in FIG. 11(b). The magnetic core 40b includes a pair of bases 41 and four center legs 43. The pair of bases 41 are substantially rectangular plate-like bodies and are arranged opposite each other with a gap in the Y direction. The four center legs 43 are leg cores with gaps (GAPs) and are arranged in a 2-row x 2-column matrix, with two in the X direction and two in the Z direction perpendicular to the X and Y directions. A primary winding Pa1 and a secondary winding Sa1, and a primary winding Pb2 and a secondary winding Sb2 of the same stage are wound around the two center legs 43 arranged in the Z direction, respectively, so that the directions of magnetic flux generation are opposite to each other. The leakage inductance of the multi-leg transformer 30b can be used as the inductance of the resonant inductor Lra, making it possible to reduce the number of parts.

[0041] The windings of the two center legs 43 arranged in the X direction are also wound so that the directions of magnetic flux generated are opposite to each other, so that the directions of magnetic flux generated in the center legs 43 adjacent to each other in the X direction and the Y direction are opposite to each other.

[0042] Steinmetz's iron loss formula is W=k·f 2.3~2.7 ·B 1.6~2 This iron loss formula can be simplified by using the square of the magnetic flux density B to obtain W=αB 2 Let's say.

[0043] As shown in Figure 12(a), when the first stage transformer T1 and the second stage transformer T2 are installed separately, if the magnetic flux density is B=4, then W=α·4 2 ×2 = 32α.

[0044] As shown in Figure 12(b), the orientation of the second-stage transformer T2 is reversed in the Z direction, and they are combined into a multi-leg transformer 30b as shown in Figure 12(b). In the multi-leg transformer 30b, the magnetic flux from one center leg 43 is halved to a magnetic flux density B = 2, as shown by the arrows, and there are two paths. Therefore, W = α2 2 ×2 paths ×2 pieces=16α, and the iron loss of the upper and lower substrates 41 is reduced by half.

[0045] (summary) (1) The power converters 1, 1a, 1b, and 1c according to the embodiments of the present invention include a transformer T n LLC resonant converter (LLC circuit 10 n , LLC circuit 50 n , LLC circuit 50a n ) (N is a natural number of 2 or more). n are integrated into multi-leg transformers 30, 30a, and 30b, in which gapped center legs 43 are arranged in a matrix in the row direction (X direction) and column direction (Z direction). In the multi-leg transformers 30, 30a, and 30b, the center legs 43 adjacent to each other in at least one of the row direction and the column direction are arranged in such a way that the directions of the generated magnetic fluxes are opposite to each other. n Primary winding Pa n is wrapped around it.

[0046] According to the power converters 1, 1a, 1b, and 1c described above in (1), the transformers T n By integrating these as multi-leg transformers 30, 30a, and 30b, multiple LLC resonant converters (LLC circuits 10 n , LLC circuit 50 n , LLC circuit 50a n ) each have a transformer T n Since the large leakage inductance of the multi-leg transformers 30, 30a, and 30b can be used as the resonant inductors Lra and Lrb, it is possible to reduce the size of the LLC resonant converter (LLC circuit 10 n , LLC circuit 50 n , LLC circuit 50a n ) do not need to be connected as separate components.

[0047] (2) In the power converter 1c described in (1) above, in the multi-leg transformer 30b, the transformers T n Primary winding Pa nis wrapped around it.

[0048] The power converter 1c described in (2) above can reduce iron loss in the upper and lower bases 41 of the multi-leg transformer 30b.

[0049] (3) The power converters 1, 1a, and 1c according to the embodiments of the present invention include a transformer T n LLC resonant converter (LLC circuit 10 n , LLC circuit 50 n , LLC circuit 50a n ) (N is a natural number of 2 or more). n The transformer T is integrated into multi-leg transformers 30, 30a, and 30b, each of which has a gap between its center leg 43 and the center leg 43, and is arranged in a matrix in the row direction (X direction) and column direction (Z direction). n is the first primary winding Pa connected in series n and the second primary winding Pb n In the multi-leg transformer 30, 30b, the center legs 43 adjacent to each other in the column direction are provided with a first primary winding Pa n and the second primary winding Pb n The coil is wound so that the direction of the magnetic flux generated is opposite to that of the coil.

[0050] According to the power converters 1, 1a, and 1c described above in (3), the transformers T n By integrating these as multi-leg transformers 30 and 30b, multiple LLC resonant converters (LLC circuits 10 n , LLC circuit 50 n ) each have a transformer T n Since the large leakage inductance of the multi-leg transformers 30 and 30b can be used as the resonant inductors Lra and Lrb, it is possible to reduce the size of the LLC resonant converter (LLC circuit 10 n , LLC circuit 50 n ) do not need to be connected as separate components.

[0051] (4) The power converter 1, 1a, 1c described in (3) above includes a control unit 20, 20a, 20c that operates N LLC resonant converters in a multiphase operation with N phases having a phase difference of 360° / N. The multi-leg transformer 30, 30b includes center legs 43 arranged in a matrix of N rows and two columns. The first primary winding Pa arranged in the column direction n and the second primary winding Pb n The N center legs 43 arranged in the row direction are wound with first primary windings Pa of different phases. n and the second primary winding Pb n are wrapped around each other.

[0052] According to the power converters 1, 1a, and 1c described in (4) above, the magnetic path is shared and the phase difference caused by the multiphase operation is utilized to reduce the composite magnetic flux, thereby reducing core loss.

[0053] (5) A charging device for charging the storage battery 3, which charges the storage battery 3 with the output voltage Vo of the power converters 1, 1a, 1b, and 1c described above in (1) to (4).

[0054] According to the charging device described in (5) above, the device can be made smaller.

[0055] (6) A vehicle (2) equipped with a storage battery (3) includes the power converters (1, 1a, 1b, 1c) described above in (1) to (4) that convert externally supplied power into an output voltage Vo for charging the storage battery (3).

[0056] According to the vehicle 2 described in (6) above, the device can be made smaller.

[0057] (7) In the multi-leg transformers 30, 30a, and 30b according to the embodiments of the present invention, the center legs 43 having gaps are arranged in a matrix in the row and column directions, and the transformers T n The transformers T are arranged in the adjacent center legs 43 in at least one of the row and column directions so that the directions of the generated magnetic fluxes are opposite to each other. nPrimary winding Pa n is wrapped around it.

[0058] According to the multi-leg transformers 30, 30a, and 30b described above in (7), the transformers T n By integrating multiple LLC resonant converters (LLC circuits 10 n , LLC circuit 50 n , LLC circuit 50a n ) each have a transformer T n Since the large leakage inductance of the multi-leg transformers 30, 30a, and 30b can be used as the resonant inductors Lra and Lrb, it is possible to reduce the size of the LLC resonant converter (LLC circuit 10 n , LLC circuit 50 n , LLC circuit 50a n ) do not need to be connected as separate components.

[0059] Although the present invention has been described above with reference to specific embodiments, it goes without saying that the above embodiments are merely examples and can be modified and implemented without departing from the spirit of the present invention. [Explanation of symbols]

[0060] 1, 1a, 1b, 1c Power Converter 2 vehicles 3. Storage battery 10, 50, 50A LLC circuit (full-bridge LLC resonant converter) 11, 11a full bridge circuit 12 Rectifier smoothing circuit 20, 20a, 20b, 20c control unit 30, 30a, 30b multi-leg transformer 40, 40a, 40b magnetic core 41 Base 42 External legs 43 Middle leg 50an LLC circuit 50n LLC circuit 51 Half-bridge circuit Cr, Cra, Crb resonant capacitors Lra, Lrb resonant inductors Pa, Pb Primary winding QH1, QH2 upper switch element QL1, QL2 lower switch element Sa, Sb Secondary winding T transformer

Claims

1. A power converter including N LLC resonant converters (N is a natural number of 2 or more) each having a transformer, The transformers of the N LLC resonant converters are integrated into a multi-legged transformer in which gapped center legs are arranged in a matrix in row and column directions; In the multi-leg transformer, the primary winding of the transformer is wound around the middle leg adjacent to at least one of the row direction and the column direction so that the direction of the generated magnetic flux is opposite.

2. 2. The power converter according to claim 1, wherein the primary windings of the multi-leg transformer are wound on the middle legs adjacent to each other in the row direction and the column direction so that the directions of the generated magnetic fluxes are opposite to each other.

3. A power converter including N LLC resonant converters (N is a natural number of 2 or more) each having a transformer, The transformers of the N LLC resonant converters are integrated into a multi-legged transformer in which gapped center legs are arranged in a matrix in row and column directions; the transformer includes a first primary winding and a second primary winding connected in series; In the multi-leg transformer, the center legs adjacent to each other in the column direction are wound such that the directions of the magnetic flux generated by the first primary winding and the second primary winding are opposite to each other.

4. a control unit that operates the N LLC resonant converters in a multiphase operation of N phases having a phase difference of 360° / N; the multi-legged transformer has the center legs arranged in a matrix of N rows and two columns, the first primary winding and the second primary winding of the same phase are wound around the two center legs arranged in the column direction so that the directions of magnetic flux generation are opposite to each other; 4. The power converter according to claim 3, wherein the first primary winding and the second primary winding of different phases are wound around the N center legs arranged in the row direction.

5. A charging device for charging a storage battery, A charging device comprising the power converter according to claim 1, which converts a DC voltage into an output voltage for charging the storage battery.

6. A vehicle equipped with a storage battery, A vehicle comprising the power converter according to claim 1 , wherein the power converter converts power supplied from outside the vehicle into an output voltage for charging the storage battery.

7. A multi-legged transformer integrating transformers of N LLC resonant converters (N is a natural number of 2 or more), in which gapped center legs are arranged in a matrix in the row and column directions, The multi-legged transformer has a primary winding wound around the middle legs adjacent to each other in at least one of the row direction and the column direction such that the directions of the generated magnetic flux are opposite to each other.

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