Resonance transducer

Abstract

m lower conversion circuits (10 1 bis m ), which configure an LLC resonant converter operated by switching on and off an upper switching element (QH) and a lower switching element (QL) together with a resonant coil (Lr), are included. n upper conversion circuits (10 m+1 bis m+n ), which configure an LLC resonant converter in which a primary winding (T1) and a resonant capacitor (Cr) interact with a resonant coil (Lr) through switching operations of the upper switching element (QH) and the lower switching element (QL). A lower matching coil (Lpd) connected in parallel to the primary windings (T1) of the m lower conversion circuits (10) 1 bis m ) is connected, and an upper matching coil (Lpu) connected in parallel to the primary windings (T1) of the n lower conversion circuits (10 1 bis m ) is connected.

Description

Technical area

[0001] The present invention relates to a resonant converter that converts an input voltage into an output voltage. Background technology

[0002] A resonant converter comprising a conversion circuit including a resonant circuit, a transformer, and a rectifier above and below a switching leg is known (see, for example, Patent Document 1). State of the art documentPatent document

[0003] Patent Document 1: JP-B2-6161982 Summary of the inventionProblems to be solved by the invention

[0004] To achieve even higher resonant converter performance or to highly integrate the circuit while maintaining the same power, it is conceivable to increase the number of conversion circuits and expand the conversion circuits in parallel. However, if the excitation inductance of the transformer varies, the problem arises that the currents between multiple conversion circuits are not balanced.

[0005] An aspect of the present invention is to provide a resonant converter that can easily achieve high performance or high integration. Means to solve the problems

[0006] A resonant converter according to one aspect of the present invention comprises: an upper switching element and a lower switching element connected in series between a positive electrode and a negative electrode of a DC power supply; and a resonant coil having one end connected to a connection point between the upper switching element and the lower switching element.

[0007] The resonant converter comprises m, where m is an integer greater than or equal to 0, lower conversion circuits, each of which comprises a transformer having a primary winding and a secondary winding, a resonant capacitor connected in series with the primary winding, and a rectifier connected to both ends of the secondary winding.

[0008] The m lower conversion circuits configure an LLC resonant converter in which the primary winding and the resonant capacitor are connected between the other end of the resonant coil and the negative electrode of the DC power supply, the LLC resonant converter being operated by turning on and off operations of the upper switching element and the lower switching element together with the resonant coil.

[0009] The resonant converter comprises n, where n is an integer greater than or equal to 0 and at least one of m and n is greater than or equal to 2, upper conversion circuits, each of which comprises the transformer, the resonant capacitor, and the rectifier.

[0010] The n upper conversion circuits configure an LLC resonant converter in which the primary winding and the resonant capacitor are connected between the other end of the resonant coil and the positive electrode of the DC power supply, the LLC resonant converter being operated by turning on and off operations of the upper switching element together with the resonant coil.

[0011] The resonant converter comprises a lower matching coil connected in parallel to the primary windings of the m lower conversion circuits and an upper matching coil connected in parallel to the primary windings of the n upper conversion circuits. Short description of the drawings Fig. 1 is a view illustrating a circuit configuration of a resonant converter according to an embodiment. Fig. 2 is a view showing a configuration example of a transformer in the Fig. 1 represents. Fig. 3 is a view showing a configuration example of a matching coil in the Fig. 1 represents. Fig. 4 is a view showing a configuration example in which the outputs of conversion circuits are connected in parallel. Fig. 5 is a view showing a configuration example in which the outputs of conversion circuits are connected in series. Fig. 6 is a view showing a configuration example of a multi-output converter. Fig. 7 is a view showing a configuration example of a multi-output converter. Fig. 8 is a view showing a configuration example of a current measuring circuit that detects the current flowing through a resonance coil. Mode of implementation of the invention

[0012] An embodiment will be described below with reference to the drawings. In the following embodiment, the configuration indicating the same function is assigned the same reference numeral, and the description thereof is omitted accordingly.

[0013] Referring to the Fig. 1, in a resonant converter 1 of the embodiment, an upper switching element QH and a lower switching element QL are connected in series as switching legs between a positive electrode of a DC power supply Vin and a negative electrode of the DC power supply Vin. For example, each of the upper switching elements QH and the lower switching elements QL includes a field-effect transistor (FET). Each of the upper switching elements QH and the lower switching elements QL has a body diode between a source and a drain.

[0014] The upper switching element QH, connected to the positive electrode of the DC power supply Vin, is an upper arm of the switching leg. The lower switching element QL, connected to the negative electrode of the DC power supply Vin, is a lower arm of the switching leg.

[0015] The resonant converter 1 comprises a resonant coil Lr, one end of which is connected to a connection point between the upper switching element QH and the lower switching element QL.

[0016] The resonant converter 1 comprises m+n conversion circuits 101 to 10m+n , each of which contains a transformer T, a resonant capacitor Cr, and a rectifier RE. m and n are integers greater than or equal to 0, and one of m and n is greater than or equal to 2.

[0017] In the m conversion circuits 101 to 10 mA primary winding T1 of each transformer T and the resonance capacitor Cr are connected in series between the other end of the resonance coil Lr and the negative electrode of the DC power supply Vin. In the m conversion circuits 101 to 10 m One end of the primary winding T1 of each transformer T is connected to the other end of the resonance coil Lr, and the other end of the primary winding T1 of the transformer T is connected to the negative electrode of the DC power supply Vin through the resonance capacitor Cr. That is, the primary winding T1 and the resonance capacitor Cr of each transformer T of the conversion circuits 101 to 10 m configure an LLC resonant converter that is operated by a switching leg on and off operation using the common resonant coil Lr. The m conversion circuits 101 to 10 m , which are provided in the lower arm, as lower conversion circuits 10 1 bis mdesignated.

[0018] In the m conversion circuits 10 m+1 until 10m+n , a primary winding T1 of each transformer T and the resonance capacitor Cr are connected in series between the other end of the resonance coil Lr and the positive electrode of the DC power supply Vin. In the n conversion circuits 10 m+1 up to 10 m+n One end of the primary winding T1 of each transformer T is connected to the other end of the resonance coil Lr, and the other end of the primary winding T1 of the transformer T is connected to the positive electrode of the DC power supply Vin through the resonance capacitor Cr. That is, the primary winding T1 and the resonance capacitor Cr of each transformer T of the conversion circuits 101 to 10 mconfigure an LLC resonant converter that is operated by a switching leg on and off operation using the common resonant coil Lr. The m conversion circuits 10 m+1 until 10m+n , which are provided in the upper arm, as upper conversion circuits 10 m+1 bis m+n designated.

[0019] In the m+n conversion circuits 101 to 10 m+n the rectifier RE rectifies an alternating current output from a secondary winding T2 of the transformer T and outputs the rectified alternating current from a high-potential output terminal V out + and a low-potential output terminal V out- off. A circuit system such as center-tap rectification, bridge rectification, voltage doubler rectification, and Cockcroft-Walton rectification can be used as the rectifier RE. In addition, the rectifier RE can also perform synchronous rectification using an FET instead of a diode. Each of the m+n conversion circuits 101 to 10 m+n includes an output capacitor Co connected between the high-potential output terminal V out + and the low-potential output terminal V out - is connected, and the rectifier RE and the output capacitor Co form a rectifier smoothing circuit.

[0020] If the m+n conversion circuits 101 to 10 m+nare provided, the resonant converter 1 can achieve high performance or highly integrate the circuits while maintaining the performance. However, if the excitation inductance of the transformer T between the m+n conversion circuits 101 to 10 m+n varies, the currents between the m+n conversion circuits 101 to 10 m+n not balanced. For example, if the excitation inductance of the transformer T of the conversion circuit 101 is lower than that of the other conversion circuits 10, a period is generated immediately after switching during which a load current I PL only flows in the conversion circuit 101. This is because an excitation current I m , which flows through the transformer T of the conversion circuit 101, is greater than that of the other conversion circuits 10 and the resonance capacitor Cr of the conversion circuit 101 is more heavily charged. The excitation current I mis a current that does not send any power to the secondary winding T2 of the transformer T, except for the load current I PL in the current flowing through the primary winding T1 of the transformer T.

[0021] Accordingly, the resonant converter 1 comprises a matching coil Lpd and a matching coil Lpu and adjusts a circulating current I CC corresponding to the excitation current of the conventional LLC resonant converter. In the resonant converter 1, the excitation inductance of the transformer T of each of the m+n conversion circuits 101 to 10 m+n set so that it is sufficiently larger (for example, greater than or equal to 10 times) than the inductance of the matching coil, and the excitation current I m is sufficiently smaller than the circulating current I CC .

[0022] As transformer T a gapless transformer can be used, as in the Fig. 2, since no gap needs to be provided in the core to reduce the excitation inductance. Fig. Figure 2(a) is a perspective view of the core. The Fig. Figure 2(b) is a sectional view showing a shaded section in the Fig. 2(a). When the transformer T is used without a gap, productivity is improved because adjustment of the gap is not required. In the example shown in the Fig. In the example shown in Figure 2, the primary winding T1 and the secondary winding T2 are sandwiched and wound around a gapless EER core (two E-type cores with cylindrical center legs overlap, and there is no gap between the center legs). The core of the transformer T is not limited but can be an EI core or a PQ core.

[0023] The matching coil Lpd is parallel to the primary winding T1 of the transformers T of the lower conversion circuits 10 1 bis mand represents the circulating current I CC the m LLC resonant converter formed in the lower arm. In other words, the transformers T of the lower conversion circuits share 10 1 bis m the matching coil Lpd, which controls the circulating currents I CC which adjusts m LLC resonant converters formed in the lower arm.

[0024] The matching coil Lpu is parallel to the primary winding T1 of the transformer T of the upper conversion circuits 10 m+1 bis m+n and adjusts the circulating current ICC of the n LLC resonant converters formed in the upper arm. In other words, the transformers T of the upper conversion circuits share 10 m+1 bis m+n the matching coil Lpu, which controls the circulating current I CC which adjusts n LLC resonant converters formed in the upper arm.

[0025] The resonant converter 1 comprises an external terminal M which is connected to a connection point between the other end of the resonant coil Lr and one end of the primary winding T1 of the transformers T of the m+n conversion circuits 10 1 bis 10 m+n The resonant converter 1 comprises an external terminal A which is connected to a connection point between the other ends of the primary windings T1 of the transformers T of the m lower conversion circuits 10 1 bis m and one end of the resonant capacitor. The resonant converter 1 comprises an external terminal B connected to a connection point between the other end of the primary winding T1 of the transformer T of the n upper conversion circuits 10 m+1 bis m+nand one end of the resonant capacitor. The matching coil Lpd is connected as an external coil between the external terminal M and the external terminal A. The matching coil Lpu is connected as an external coil between the external terminal M and the external terminal B.

[0026] The resonant converter 1 can convert the circulating currents I CC the m+n conversion circuits 101 to 10 m+n collectively by adjusting only the inductances of the matching coil Lpd and the matching coil Lpu. Consequently, the currents in the resonant converter 1 are balanced, even if the conversion circuits 10 1 bis 10 m+n be expanded in parallel so that high performance or high integration can be easily achieved.

[0027] The resonant converter 1 can convert the circulating current I CCby the matching coil Lpd and the matching coil Lpu, so that the specification of the resonant converter 1 can be easily changed without rewinding the m+n transformers T.

[0028] In the resonant converter 1, a resonance current ir, which flows through the primary side of the m+n conversion circuits 101 to 10 m+n flows through a resonance coil Lr, and the current of (m+n)ir flows in the resonance coil Lr. Consequently, the following formula (1) is obtained when the inductance L1 of the resonance coil Lr in the case where the number of conversion circuits 10 is one, and the inductance L2 of the resonance coil Lr in the case where the number of conversion circuits 10 is (m+n), for the voltage v applied to the resonance coil Lr L be compared with each other. [Mathematical Formula 1] νL=L1dirdt=L2d(m+n)irdt=L1(m+n)d(m+n)irdt

[0029] The inductance L2 of the resonance coil Lr can be reduced to 1 / (m+n) of the inductance L1 of the resonance coil Lr when the number of conversion circuits is 10 (m+n), and when the number of conversion circuits is 10 (m+n). Therefore, when the number of conversion circuits is 10 (m+n), the size of the resonance coil Lr can be reduced, and a planar structure or a coreless structure can be obtained.

[0030] In the resonant converter 1, the current balance is not greatly affected, since the resonant coil Lr is connected to the m+n conversion circuits 101 to 10 m+n is common, even if the capacity C1 to C m+n of the resonance capacitor Cr varies. As shown in the following formula (2), a resonance frequency ωr is unified. In formula (2), Cr is an average value of the capacitances C1 to C m+n . [Mathematical Formula 2] ωr=1Lrm+n∑j=1m+nCj≈1LrCr

[0031] As in the Fig. 3(a), the matching coil Lpd and the matching coil Lpu may be independent coils whose winding is wound around each core, or, as shown in the Fig. As shown in Figure 3(b), the matching coil Lpd and the matching coil Lpu may be a coupling coil whose winding is wound around the same core. Although the schematic view of the coupling coil is shown in Fig. 3(b) is shown as a split winding for simplicity, in practice a sandwich winding or a bifilar winding can be used.

[0032] If the matching coil Lpd and the matching coil Lpu are independent coils, it is required that the number of lower conversion circuits is 10 1 bis m and the number of upper conversion circuits 10 m+1 bis m+n are equal (m = n). The inductance L ind can be calculated using the number of turns Nind and the magnetic resistance R of the core as L ind = N ind 2 / R can be expressed.

[0033] In the case where the matching coil Lpd and the matching coil Lpu are the coupling coil, the matching coil Lpd and the matching coil Lpu are formed into a union connection in which magnetic fluxes are applied when the current flows from the connection point of the windings to each of the windings (M → A, B). Even if the number of lower conversion circuits is 10 1 bis m of the number of upper conversion circuits 10 m+1 bis m+n differs (even if m≠ n), the currents between m+n conversion circuits 101 to 10 m+n be balanced.

[0034] When the matching coil Lpd and the matching coil Lpu are the coupling coil, the resonant converter 1 also has the following effects.

[0035] The inductance variation between the matching coil Lpd and the matching coil Lpu can be reduced.

[0036] The number of cores used for the matching coil Lpd and the matching coil Lpu can be one.

[0037] The number of windings of the matching coil Lpd and the matching coil Lpu can be reduced compared to independent coils.

[0038] In the case of the coupling coil, the self-inductance L CP and the mutual inductance M of each winding using the number of turns N CP and the magnetic resistance R of the core, and assuming that the self-inductance L CP and the mutual inductance M are tightly coupled (k = 1), the self-inductance L CP and the mutual inductance M is expressed as follows. LCP=NCP2 / R M=kNCPNCP / R=LCP

[0039] When current i flows from the connection point of the windings to each of the windings, the voltages between the terminals V MA , V MB the coupling coil of the following equation: VMA=VMB=(LCP+M)di / dt=2LCPdi / dt, and the combined inductance for the current i in each winding is twice the self-inductance L CP .

[0040] Consequently, to obtain an inductance equal to that of the independent coil in the coupling coil (L ind = 2L CP ), the number of turns N CP the winding in the coupling coil N CP = N ind / √2. This means that if the magnetization curves are linear and the magnetic resistance is the same, the number of turns N CP of the windings in the coupling coil compared to the number of turns N ind of the windings in the independent coil can be reduced to 1 / √2 (= 0.71).

[0041] In one in the Fig. The outputs of the m+n conversion circuits 101 to 10 m+n connected in parallel, and an output capacitor Co is connected to a common output Vo. The matching coil Lpd and the matching coil Lpu can be independent coils or the coupling coil. The output capacitor Co can be divided and connected to each of the m+n conversion circuits 101 to 10 m+n The resonant converter 1a can easily achieve the high output current by connecting the outputs of the m+n conversion circuits 101 to 10 m+n be connected in parallel.

[0042] In one in the Fig. The outputs of the m+n conversion circuits 101 to 10 m+nconnected in parallel, and an output capacitor Co is commonly connected to a total output Vo. The matching coil Lpd and the matching coil Lpu can be independent coils or the coupling coil. The output capacitor Co can be divided and connected to each of the m+n conversion circuits 101 to 10 m+n The resonant converter 1b can easily achieve the high output voltage by connecting the outputs of the m+n conversion circuits 101 to 10 m+n be connected in series.

[0043] A resonant converter 1c in the Fig. 6 is a multi-output converter that implements multiple outputs (Vo1, Vo2, Vo3) in which parallel output and series output are mixed by the m+n conversion circuits 101 to 10 m+n are divided into three sets. The resonant converter 1c comprises a first output circuit in which the lower conversion circuit 101 and the upper conversion circuit 10 m+1connected in parallel and which outputs the output Vo1. The resonant converter 1c comprises a second output circuit in which the lower conversion circuits 10 2 bis j and the upper conversion circuits 10 m+1 bis m+j connected in series to output Vo2. The resonant converter 1c includes a third output circuit in which the lower conversion circuits 10 j+1 bis m and the upper conversion circuits 10 m+j+1 bis m+n are connected in parallel to output Vo3. j is an integer from 1 to m, n.In the Fig. 6, output capacitors Co1 to Co3 are provided in each output circuit. The output capacitors Co1 to Co3 can be integrated into the m+n conversion circuits 101 to 10 m+n be divided.

[0044] The resonant converter 1c can convert the currents between the conversion circuits 101 to 10 m+nEven with multiple outputs, the matching coil Lpd and the matching coil Lpu can be compensated. The matching coil Lpd and the matching coil Lpu of the resonant converter 1c are independent coils. Consequently, the number of lower conversion circuits is 10. 1 bis m equal to the number of upper conversion circuits 10 m+1 bis m+n (m = n). A partial sum of the 10 1 bis m output power and a partial sum of the upper conversion circuits 10 m+1 bis m+n output power are adjusted so that they are equal.

[0045] Since the current between the conversion circuits 101 to 10 m+n can be compensated by the matching coil Lpd and the matching coil Lpu, a turns ratio of the transformer T of each output circuit may be different.

[0046] A resonant converter 1d in the Fig. 7 is a multi-output converter that implements multiple outputs (Vo1, Vo2, Vo3, Vo4) in which single output, parallel output and series output are mixed by the m+n conversion circuits 10 1 bis 10 m+n be divided into four sets. The resonant converter 1d comprises the lower conversion circuit 101, which outputs the output Vo1 as the first output circuit. The resonant converter 1d comprises the upper conversion circuit 10 m+1 , which outputs the output Vo2 as a second output circuit. The resonant converter 1d comprises a third output circuit in which the lower conversion circuits 10 2 bis j and the upper conversion circuits 10 m+1 bis m+j connected in series to output Vo3. The resonant converter 1d comprises a fourth output circuit in which the lower conversion circuits 10 +1 bis m and the upper conversion circuits 10 m+j+1 bis m+nare connected in parallel to output Vo4. In the Fig. 6, output capacitors Co1 to Co4 are provided in each output circuit. The output capacitors Co1 to Co4 can be integrated into the m+n conversion circuits 101 to 10 m+n be divided.

[0047] The matching coil Lpd and the matching coil Lpu of the resonant converter 1d are the coupling coils. Consequently, the number of lower conversion circuits can be 10. 1 bis m and the number of upper conversion circuits 10 m+1 bis m+n be different (m≠ n). In each output circuit, the currents between the conversion circuits 101 to 10 m+n be balanced, even if the number of conversion circuits used is 10 from the lower conversion circuits 1 bis m and the upper conversion circuits 10 m+1 bis m+nbetween the upper and lower sides or even if the subtotal of the power delivered by the conversion circuits is different between the upper and lower sides.

[0048] Since the current between the conversion circuits 101 to 1 0m+n can be compensated by the matching coil Lpd and the matching coil Lpu, a turns ratio of the transformer T of each output circuit may be different.

[0049] The resonant converters 1 to 1d include the external terminals M, A, B, which connect the matching coil Lpd and the matching coil Lpu as external coils. The external terminals A, B can be used as the connection terminal of a current measuring circuit 2 in the Fig. 8 can be used.

[0050] The current measuring circuit 2 includes two parallel capacitors Cs connected in series between the external connection terminals A, B. The parallel capacitor Cs is set to have a capacitance sufficiently smaller than that of the resonant capacitor Cr so as not to affect the operation of the resonant converter 1. The current measuring circuit 2 includes a measuring resistor Rs connected between a junction point of two parallel capacitors Cs and the negative electrode of the DC power supply Vin. The current flowing through the measuring resistor Rs is shunted by a resonant coil current between the m+n resonant capacitors Cr and the two parallel capacitors Cs. The voltage vs generated by the current is in the measuring resistor Rs is input as a current measurement value to a control unit, which controls the switching on and off of the upper switching element QH and the lower switching element QL.

[0051] The current flowing through the measuring resistor Rs is determined by a capacitance ratio between the resonance capacitor Cr and the parallel capacitor Cs, regardless of the number of conversion circuits 101 to 10 m+n . Consequently, the current measuring circuit 2 can easily detect the current flowing through the resonant coil Lr. A current measuring circuit 2 can be used regardless of the number of conversion circuits 101 to 10 m+n be provided and it is not necessary that a gain adjustment of the control circuit according to the number of conversion circuits 101 to 10 m+n is changed.

[0052] As described above, the embodiment includes the upper switching element QH and the lower switching element QL, which are connected in series to both ends of the DC power supply Vin. The embodiment includes the resonance coil Lr, one end of which is connected to the connection point between the upper switching element QH and the lower switching element QL. The embodiment includes the m lower conversion circuits 10. 1 bis m , which include the transformer T, which includes the primary winding T1 and the secondary winding T2, the resonant capacitor Cr, which is connected in series with the primary winding T1, and the rectifier RE, which is connected to both ends of the secondary winding T2. In the m lower conversion circuits 10 1 bis mThe primary winding T1 and the resonant capacitor Cr are connected between the other end of the resonant coil Lr and the negative electrode of the DC power supply Vin, and configure the LLC resonant converter, which is operated by the on / off operations of the upper switching element QH and the lower switching element QL together with the resonant coil Lr. The embodiment includes the n upper conversion circuits 10 m+1 bis m+n , which include the transformer T, the resonant capacitor Cr and the rectifier RE. In the n upper conversion circuits 10 m+1 bis m+nThe primary winding T1 and the resonance capacitor Cr are connected between the other end of the resonance coil Lr and the positive electrode of the DC power supply Vin, and configure the LLC resonant converter, which is operated by the on / off operations of the upper switching element QH and the lower switching element QL together with the resonance coil Lr. The embodiment includes the matching coil Lpd (lower matching coil) connected in parallel with the primary windings T1 of the m lower conversion circuits 10. 1 bis m The embodiment comprises the matching coil Lpu (upper matching coil) connected in parallel to the primary windings T1 of the n lower conversion circuits 10 1 bis m is connected.

[0053] With this configuration, the currents are balanced even if the lower conversion circuits 10 1 bis m and the upper conversion circuits 10 m+1 bis m+nbe expanded in parallel so that high performance or high integration can be easily achieved.

[0054] Furthermore, in the embodiment, the matching coil Lpd and the matching coil Lpu may be the coupling coil.

[0055] Even if the number of lower conversion circuits is 10 1 bis m of the number of upper conversion circuits 10 m+1 bis m+n differs (even if m≠ n), with this configuration the currents between the m+n conversion circuits 101 to 10 m+n The matching coil Lpd and the matching coil Lpu can reduce inductance fluctuations. The number of cores used for the matching coil Lpd and the matching coil Lpu can be one. The number of windings of the matching coil Lpd and the matching coil Lpu can be reduced compared to the case of the independent coil.

[0056] In addition, according to the embodiment, the excitation inductances of the transformers T of the lower conversion circuits 10 1 bis m and the upper conversion circuits 10 m+1 bis m+n set larger than the inductances of the matching coil Lpd and the matching coil Lpu, so that the gapless core can be used for the transformer T.

[0057] In addition, in the resonant converter 1a, the outputs of the m lower conversion circuits 10 1 bis m and the outputs of the n upper conversion circuits 10 m+1 bis m+n connected in parallel.

[0058] With this configuration, the resonant converter 1a can easily achieve the high current of the output.

[0059] In addition, in the resonant converter 1b, the outputs of the m lower conversion circuits 10 1 bis m and the outputs of the n upper conversion circuits 10 m+1 bis m+n connected in series.

[0060] With this configuration, the resonant converter 1b can easily achieve the high current of the output.

[0061] In addition, the resonant converters 1c, 1d are the multiple output converters in which the outputs of the m lower conversion circuits 10 1 bis m and the outputs of the n upper conversion circuits 10 m+1 bis m+n are divided into a multitude of sentences.

[0062] With this configuration, the resonant converters 1c, 1d can easily handle multiple outputs.

[0063] In addition, the embodiment includes the external terminal M (middle external terminal) connected to the connection point between the other end of the resonance coil Lr and one end of the primary winding T1 of the lower conversion circuits 10 1 bis m and the upper conversion circuits 10 m+1 bis m+nThe embodiment includes the external terminal A (lower external terminal) connected to the connection point between the other end of the primary winding T1 of each of the lower conversion circuits 10 1 bis m and one end of the resonance capacitor Cr. The embodiment includes the external terminal B (upper external terminal) connected to the connection point between the other end of the primary winding T1 of the upper conversion circuits 10 m+1 bis m+n and one end of the resonance capacitor Cr. The matching coil Lpd is connected as an external coil between the external terminal M and the external terminal A, and the matching coil Lpu is connected as an external coil between the external terminal M and the external terminal B.

[0064] With this configuration, the matching coil Lpd and the matching coil Lpu can easily adjust the inductance. The external terminals A and B can be used as the terminals for connecting the current measuring circuit 2, and the current flowing through the resonant coil Lr can be easily detected by the current measuring circuit 2.

[0065] Although the present invention has been described above with reference to the specific embodiment, it is needless to say that the above-described embodiment is the example and can be changed and implemented without departing from the spirit of the present invention. Description of reference symbols 1, 1a to 1d Resonance converter 10 1 bis m lower conversion circuit 10 m+1 bis m+n upper conversion circuit Cr resonance capacitor Lpd adjustment coil (lower adjustment coil) Lpu adjustment coil (upper adjustment coil) Lr resonance coil QH upper switching element QL lower switching element RE rectifier T1 primary winding T2 secondary winding T Transformer Vin DC power supply QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP-B2-6161982

[0003]

Claims

[1] A resonant converter comprising: an upper switching element and a lower switching element connected in series between a positive electrode and a negative electrode of a DC power supply; a resonance coil having one end connected to a connection point between the upper switching element and the lower switching element; m, where m is an integer greater than or equal to 0, lower conversion circuits comprising a transformer having a primary winding and a secondary winding, a resonant capacitor connected in series with the primary winding, and a rectifier connected to both ends of the secondary winding, wherein the m lower conversion circuits configure an LLC resonant converter in which the primary winding and the resonant capacitor are connected between the other end of the resonant coil and the negative electrode of the DC power supply, the LLC resonant converter being operated by turning on and off operations of the upper switching element and the lower switching element together with the resonant coil; n, where n is an integer greater than or equal to 0 and at least one of m and n is greater than or equal to 2, upper conversion circuits, each of which includes the transformer, the resonance capacitor, and the rectifier, the n upper conversion circuits configuring an LLC resonant converter in which the primary winding and the resonance capacitor are connected between the other end of the resonance coil and the positive electrode of the DC power supply, the LLC resonant converter being operated by turning on and off operations of the upper switching element and the lower switching element together with the resonance coil; a lower matching coil connected in parallel to the primary windings of the m lower conversion circuits; and an upper matching coil connected in parallel to the primary windings of the n upper conversion circuits. [2] The resonant converter according to claim 1, wherein the lower matching coil and the upper matching coil are a coupling coil. [3] The resonant converter according to claim 1 or 2, wherein the excitation inductances of the transformers of the lower conversion circuit and the upper conversion circuit are set larger than the inductances of the lower matching coil and the upper matching coil. [4] The resonant converter according to claim 1, wherein the excitation inductances of the transformers of the lower conversion circuit and the upper conversion circuit are set to be greater than or equal to 10 times the inductances of the lower matching coil and the upper matching coil. [5] The resonant converter according to claim 1 or 2, wherein outputs of the m lower conversion circuits and outputs of the n upper conversion circuits are connected in parallel. [6] The resonant converter according to claim 1 or 2, wherein outputs of the m lower conversion circuits and outputs of the n upper conversion circuits are connected in series. [7] The resonant converter according to claim 1 or 2, wherein the resonant converter is a multi-output converter in which outputs of the m lower conversion circuits and outputs of the n upper conversion circuits are divided into a plurality of sets. [8] The resonant converter according to claim 1 or 2, comprising: a middle external connection terminal connected to a connection point between the other end of the resonance coil and one end of the primary winding of both the upper conversion circuit and the lower conversion circuit; a lower external terminal connected to a connection point between another end of the primary winding of the lower conversion circuit and one end of the resonance capacitor; and an upper external terminal connected to a connection point between another end of the primary winding of the upper conversion circuit and one end of the resonance capacitor, wherein the lower matching coil is connected as an external coil between the middle external terminal and the lower external terminal, and the upper matching coil is connected as an external coil between the middle external terminal and the upper external terminal. [9] The resonant converter according to claim 1 or 2, comprising a current measuring circuit connected between a connection point between the primary winding of the lower conversion circuit and the resonant capacitor and a connection point between the primary winding of the upper conversion circuit and the resonant capacitor, and detecting current flowing through the resonant coil.

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