_R5, a third lower rectification switch S_R6, a fourth upper rectification switch S_R7and a fourth lower rectification switch S_R8. The third upper rectification switch S_R5and the third lower rectification switch S_R6are connected in series to form a third rectification bridge. The fourth upper rectification switch S_R7and the fourth lower rectification switch S_R8are connected in series to form a fourth rectification bridge. The third rectification bridge and the fourth rectification bridge are connected in parallel. The third synchronous rectification switch group includes a fifth upper rectification switch S_R9, a fifth lower rectification switch S_R10, a sixth upper rectification switch S_R11and a sixth lower rectification switch S_R12. The fifth upper rectification switch S_R9and the fifth lower rectification switch S_R10are connected in series to form a fifth rectification bridge. The sixth upper rectification switch S_R11and the sixth lower rectification switch S_R12are connected in series to form a sixth rectification bridge. The fifth rectification bridge and the sixth rectification bridge are connected in parallel. In some other embodiments, the first upper rectification switch S_R1, the first lower rectification switch S_R2, the second upper rectification switch S_R3, the second lower rectification switch S_R4, the third upper rectification switch S_R5, the third lower rectification switch S_R6, the fourth upper rectification switch S_R7, the fourth lower rectification switch S_R8, the fifth upper rectification switch S_R9, the fifth lower rectification switch S_R10, the sixth upper rectification switch S_R11and the sixth lower rectification switch S_R12are respectively formed by an active switch, such as a metal oxide semi-conductor field effect transistor. Since the first synchronous rectification switch group, the second synchronous rectification switch group and the third synchronous rectification switch group of the output switch group 3 in the three-phase LLC power conversion circuit 1 are full bridge topologies, the voltage stress of each rectification switch in the first synchronous rectification switch group, the second synchronous rectification switch group and the third synchronous rectification switch group can be reduced, and the control freedom of the output switch group 3 can be increased. In the above embodiment, the first input switch bridge, the first transformer T₁, the first resonant element RE_A1, the second resonant element RE_A2and the first synchronous rectification switch group collaboratively form the first phase of the three-phase LLC power conversion circuit 1. The second input switch bridge, the second transformer T₂, the first resonant element RE_B1, the second resonant element RE_B2and the second synchronous rectification switch group collaboratively form the second phase of the three-phase LLC power conversion circuit 1. The third transformer T₃, the first resonant element RE_C1, the second resonant element RE_C2and the third synchronous rectification switch group collaboratively form the third phase of the three-phase LLC power conversion circuit 1.

The control unit 4 is electrically connected to the input switch group 2 and the output switch group 3 for detecting each zero-crossing point of the input voltage V_in, the output voltage V_oand the output current in each phase. Based on the detection results, the control unit 4 controls the first upper input switch Q₁to the third lower input switch Q₆of the input switch group 2 to perform switching operation, and controls the first upper rectification switch S_R1to the sixth lower rectification switch S_R12of the output switch group 3 to perform synchronous rectification switching operation. Preferably but not exclusively, the switching actions of any two upper input switches in the input switch group 2 are interleaved with 120 degrees from each other, and the switching actions of the upper input switch and the lower input switch in each input switch bridge of the input switch group 2 are complementary with reasonable deadtime to prevent shoot-through. The switching actions of the upper rectification switch and the lower rectification switch in each rectification bridge of the output switch group 3 are complementary with reasonable deadtime to prevent shoot-through. In addition, according to a ratio of the output voltage V_oand the input voltage V_in, the control unit 4 further controls a switching state of at least one rectification switch of the synchronous rectification switch group in each phase of the output switch group 3 to lead or lag the corresponding input switch in the input switch bridge with the same phase (i.e., the input switch is corresponding to the at least one rectification switch to lead or lag at turned on phase angle), and/or adjusts all input switches in each input switch bridge of the input switch group 2 to increase a duty cycle, so that the ratio of the output voltage V_oto the input voltage V_inis increased. In addition, the control unit 4 further adjusts the switching frequency of all input switches in the input switch group 2 according to the output voltage V_o, a reference voltage V_refand the soft switching setting condition, so that all input switches of the input switch group 2 perform soft switching.

In an embodiment, the three-phase LLC power conversion circuit 1 has each phase to be operated with a phase difference of 120 degrees, and the two switches of the switch bridge in each phase are operated complementary. Therefore, FIG. 3 only illustrates some operating parameters of the three-phase LLC power conversion circuit 1 to describe the technology of the present disclosure. In FIG. 3 to FIG. 6, symbols Q_1A, Q_3A, Q_5Arespectively represent the switching states of the first upper input switch Q₁, the second upper input switch Q₃and the third upper input switch Q₅in the input switch group 2. Symbols Q_7A, Q_8Arespectively represent the switching states of the synchronous rectification switches (i.e., the diagonal first upper rectification switch S_R1and the second lower rectification switch S_R4) which are in the same phase with and corresponding to the first upper input switch Q₁. The switching state of the first upper rectification switch S_R1leads the switching state of the first upper input switch Q₁by a first time ΔT₁, and the switching state of the second lower rectification switch S_R4lags the switching state of the first upper input switch Q₁by a second time ΔT₂. Symbols Q_9A, Q_10Arespectively represent the switching states of the synchronous rectification switches (i.e., the diagonal third upper rectification switch S_R5and the fourth lower rectification switch S_R8) which are in the same phase with and corresponding to the second upper input switch Q₃. The switching state of the third upper rectification switch S_R5leads the switching state of the second upper input switch Q₃, and the fourth lower rectification switch S_R8lags the switching state of the second upper input switch Q₃. Symbols Q_11A, Q_12Arespectively represent the switching states of the synchronous rectification switches (i.e., the diagonal fifth upper rectification switch S_R9and the sixth lower rectification switch S_R12) which are in the same phase with and corresponding to the third upper input switch Q₅. The switching state of the fifth upper rectification switch S_R9leads the switching state of the third upper input switch Q₅, and the switching state of the sixth lower rectification switch S_R12lags the switching state of the third upper input switch Q₅. Symbol I_p1is the current flowing through the primary winding of the first transformer T₁in the first phase of the three-phase LLC power conversion circuit 1. Symbol I_M1is the current flowing through the magnetizing inductance L_m1of the first transformer T₁in the first phase of the three-phase LLC power conversion circuit 1. Symbol I_s1is the current flowing through the secondary winding of the first transformer T₁in the first phase of the three-phase LLC power conversion circuit 1.

As shown in FIG. 3, the control unit 4 controls the switching state of at least one rectification switch of the synchronous rectification switch group in each phase of the output switch group 3 to lead the switching state of the synchronous rectification switch in the same phase according to the ratio of the output voltage V_oto the input voltage V_in. In addition, the control unit 4 controls the switching state of the corresponding input switch in the input switch bridge, and the switching state of at least one remaining rectification switch of the synchronous rectification switch group in each phase of the output switch group 3 lags the switching state of the corresponding input switch of the input switch bridge in the same phase. As shown in FIG. 4, alternatively, the control unit 4 can also be changed to control at least one rectification switch of the synchronous rectification switch group in each phase of the output switch group 3 to perform synchronous rectification switching, and control the switching state of at least one remaining rectification switch of the synchronous rectification switch group in each phase of the output switch group 3 lags the switching state of the corresponding input switch of the input switch bridge in the same phase. As shown in FIG. 5 and FIG. 6, alternatively, the control unit 4 can also be changed to control at least one rectification switch of the synchronous rectification switch group in each phase of the output switch group 3 to perform synchronous rectification switching, and control the switching state of at least one remaining rectification switch of the synchronous rectification switch group in each phase of the output switch group 3 leads the switching state of the corresponding input switch of the input switch bridge in the same phase by a third time ΔT. In addition, as shown in FIG. 6, the control unit 4 further adjusts the switching frequencies of all input switches of the input switch group 2 according to the soft switch setting conditions. All input switches of the input switch group 2 perform soft switching.

From the above, the three-phase LLC power conversion circuit 1 of the present disclosure can not only reduce the frequency range of the switch, but also has lower RMS current, lower peak current and better magnetic integration. Furthermore, since the control unit 4 controls two control freedoms, namely the phase-shift and the switching frequency of the switch, the reactive current increased due to the change of the resonant frequency can be solved, and the switch can be accurately controlled for soft switching.

In some embodiments, the control unit 4 includes a zero current detection (ZCD) circuit 41, a gain control circuit 42, a first driver 43, a subtractor 44, a compensation circuit 45, a voltage-controlled oscillator (VCO) 46 and a second driver 47. The first driver 43 is configured to drive the first upper rectification switch S_R1to the sixth lower rectification switch S_R12 of the output switch group 3 to operate. The zero current detection circuit 41 is electrically connected to the secondary windings of the first transformer T₁, the second transformer T₂and the third transformer T₃, and configured to detect the zero-crossing point of the output current in each phase of the three-phase LLC power conversion circuit 1. The gain control circuit 42 is configured to detect the input voltage V_inreceived by the three-phase LLC power conversion circuit 1 and the output voltage V_ooutputted by the three-phase LLC power conversion circuit 1, and receives the detection result of the zero current detection circuit 41. The first driver 43 is controlled to drive the first upper rectification switch S_R1to the sixth lower rectification switch S_R12of the output switch group 3 according to the detection results of the input voltage V_in, the output voltage V_oand the zero-crossing point of the output current in each phase, so as to perform synchronous rectification switching operation. The gain control circuit 42 further controls the switching state of at least one rectification switch of the synchronous rectification switch group in each phase of the output switch group 3 to lead or lag the switching state of the corresponding input switch of the input switch bridge in the same phase according to the ratio of the output voltage V_oand the input voltage V_in. (i.e., the input switch is corresponding to the at least one rectification switch to lead or lag at turned on phase angle), and/or adjusts all input switches in each input switch bridge of the input switch group 2 to increase a duty cycle, so that the ratio of the output voltage V_oto the input voltage V_inis increased. The subtractor 44 is configured to perform a subtraction operation on the output voltage V_oand the reference voltage V_ref. The compensation circuit 45 is configured to receive the soft switch setting condition and the operation result of the subtractor 44, and output a compensation signal according to the soft switching setting condition and the calculation result of the subtractor 44. The voltage-controlled oscillator 46 generates a switching signal having frequencies of the first upper input switch Q₁to the third lower input switch Q₆according to the compensation signal. The second driver 47 is configured to drive the first upper input switch Q₁to the third lower input switch Q₆of the input switch group 2 to perform soft switching according to the switching signal.

Please refer to FIG. 1 again. The control method of the present disclosure includes the following steps.

In a step S1, the control unit 4 detects each zero-crossing point of the input voltage V_inreceived by the three-phase LLC power conversion circuit 1, the output voltage V_ooutputted by the three-phase LLC power conversion circuit 1 and the output current in each phase of the three-phase LLC power conversion circuit 1.

In a step S2, based on detection results of the input voltage V_in, the output voltage V_oand the output current in each phase of the three-phase LLC power conversion circuit 1, the control unit 4 controls the first upper input switch Q₁to the third lower input switch Q₆of the input switch group 2 to perform switching operation, and controls the first upper rectification switch S_R1to the sixth lower rectification switch S_R12of the output switch group 3 to perform synchronous rectification switching operation. Moreover, according to a ratio of the output voltage V_oand the input voltage V_in, the control unit 4 further controls a switching state of at least one rectification switch of the synchronous rectification switch group in each phase of the output switch group 3 to lead or lag the corresponding input switch in the input switch bridge with the same phase, and/or adjusts all input switches in each input switch bridge of the input switch group 2 to increase a duty cycle, so that the ratio of the output voltage V_oto the input voltage V_inis increased. In addition, the control unit 4 further adjusts the switching frequencies of all input switches in the input switch group 2 according to the output voltage V_o, the reference voltage V_refand the soft switching setting condition, so that all input switches of the input switch group 2 perform soft switching.

FIG. 7 is a schematic diagram of a circuit topology of a three-phase LLC power conversion circuit according to a second embodiment of the present disclosure. In the embodiment, the structures, elements and functions of the three-phase LLC power conversion circuit 1a are similar to those of the three-phase LLC power conversion circuit 1 in FIG. 2, and are not redundantly described herein. In the embodiment, the first upper input switch Q₁, the first lower input switch Q₂, the second upper input switch Q₃, the second lower input switch Q₄, the third upper input switch Q₅and the third lower input switch Q₆in the input switch group 2 of the three-phase LLC power conversion circuit 1a are electrically connected in a cascade manner.

FIG. 8 is a schematic diagram of a circuit topology of a three-phase LLC power conversion circuit according to a third embodiment of the present disclosure. In the embodiment, the structures, elements and functions of the three-phase LLC power conversion circuit 1b are similar to those of the three-phase LLC power conversion circuit 1 in FIG. 2, and are not redundantly described herein. In the embodiment, the first synchronous rectification switch group of the output switch group 3 in the three-phase LLC power conversion circuit 1b is changed to include a first upper rectification switch S_R1aand a first lower rectification switch S_R2aconnected in series to form a half-bridge topology. The second synchronous rectification switch group of the output switch group 3 in the three-phase LLC power conversion circuit 1b is changed to include a second upper rectification switch S_R3aand a second lower rectification switch S_R4aconnected in series to form a half-bridge topology. The third synchronous rectification switch group of the output switch group 3 in the three-phase LLC power conversion circuit 1b is changed to include a third upper rectification switch S_R5aand a third lower rectification switch S_R6aconnected in series to form a half-bridge topology.

Please refer to FIG. 9, FIG. 10 and FIG. 11. FIG. 9 is a schematic diagram of a circuit topology of a three-phase LLC power conversion circuit according to a fourth embodiment of the present disclosure. FIG. 10 and FIG. 11 show the operating waveforms of the three-phase LLC power conversion circuit when the control unit of the three-phase LLC power conversion circuit is performed in different implementation modes. In the embodiment, the structures, elements and functions of the three-phase LLC power conversion circuit 1c are similar to those of the three-phase LLC power conversion circuit 1b in FIG. 8, and are not redundantly described herein. In the embodiment, the plurality of primary windings T_1p, T_2p, T_3pof the three-phase transformer T in the three-phase LLC power conversion circuit 1c are delta-connected (i.e., Δ connection), and the plurality of secondary windings T_1s, T_2s, T_3sare delta-connected (i.e., Δ connection).

As shown in FIG. 10, the control unit 4 controls the switching state of at least one rectification switch of the synchronous rectification switch group in each phase of the output switch group 3 to lead the switching state of the corresponding input switch in the input switch bridge in the same phase according to the ratio of the output voltage V_oand the input voltage V_in(i.e., the switching states of the first upper rectification switch S_R1a, the second upper rectification switch S_R3a, and the third upper rectification switch S_R5alead the switching states of the first upper input switch Q₁, the second upper input switch Q₃and the third upper input switch Q₅, respectively.) As shown in FIG. 11, the control unit 4 is changed to control at least one rectification switch of the synchronous rectification switch group in each phase of the output switch group 3 to perform synchronous operation according to a ratio of the output voltage V_oand the input voltage V_in, and control the switching state of at least one remaining rectification switch of the synchronous rectification switch group in each phase of the output switch group 3 to lag the switching state of the corresponding input switch in the same phase of the input switch bridge (i.e., the switching state of the first upper rectification switch S_R1alags the switching state of the first upper input switch Q₁).

Please refer to FIG. 12 and FIG. 13. FIG. 12 is a schematic diagram of a circuit topology of a three-phase LLC power conversion circuit according to a fifth embodiment of the present disclosure. FIG. 13 shows the operating waveforms of the three-phase LLC power conversion circuit when the control unit of the three-phase LLC power conversion circuit is operated. In the embodiment, the three-phase LLC power conversion circuit 1d shows the detailed circuit topology of the three-phase LLC power conversion circuit 1b shown in FIG. 8. The plurality of first resonant elements RE_A1, ER_B1, RE_C1in the three-phase LLC power conversion circuit 1c shown in FIG. 8 are star-connected (i.e., Y-connected) and can be respectively formed by capacitors C_r1, C_r2, C_r3, as shown in FIG. 12. The plurality of second resonant elements RE_A2, ER_B2, RE_C3are delta-connected (i.e., Δ connection) and can be respectively formed by resonant inductors L_r1, L_r2, L_r3. Symbol I_c1, I_c2, I_c3are the currents flowing through the capacitors C_r1, C_r2, C_r3, respectively. Symbol I_L1, I_L2, I_L3are the currents flowing through resonant inductors L_r1, L_r2, L_r3, respectively. Symbol I_s1, I_s2, I_s3are the currents flowing through the secondary windings of the first transformer T₁, the second transformer T₂, the third transformer T₃, respectively.

FIG. 14 is a schematic diagram of a circuit topology of a three-phase LLC power conversion circuit according to a sixth embodiment of the present disclosure. In the embodiment, the structures, elements and functions of the three-phase LLC power conversion circuit 1e are similar to those of the three-phase LLC power conversion circuit 1b in FIG. 8, and are not redundantly described herein. In the embodiment, the first upper input switch Q₁, the first lower input switch Q₂, the second upper input switch Q₃, the second lower input switch Q₄and the third upper input switch Q₅and the third lower input switch Q₆in the input switch group 2 of the three-phase LLC power conversion circuit 1e are electrically connected in a cascade manner.

From the above, it can be seen that the input switch group 2 of the three-phase LLC power conversion circuit can be one of the circuit topology of the input switch group 2 of the three-phase LLC power conversion circuit 1 shown in FIG. 2 and the circuit topology of the input switch group 2 of the three-phase LLC power conversion circuit 1a shown in FIG. 7. Moreover, the output switch group 3 of the three-phase LLC power conversion circuit can be one of the circuit topology of the output switch group 3 of the three-phase LLC power conversion circuit 1 shown in FIG. 2 and the circuit topology of the output switch group 3 of the three-phase LLC power conversion circuit 1b shown in FIG. 8. Preferably but not exclusively, the plurality of first resonant elements RE_A1, RE_B1, RE_C1are star-connected (i.e., Y-connected) or delta-connected (i.e., A connection), and respectively formed by capacitors or respectively formed by resonant inductors. Preferably but not exclusively, the plurality of second resonant elements RE_A2, RE_B2, RE_C2are star-connected (i.e., Y-connected) or delta-connected (i.e., Δ connection), and respectively formed by capacitors or respectively formed by resonant inductors. It is noted that the circuit topologies of the input switch group 2, the output switch group 3 and the resonant circuit group are not limited to the above-mentioned embodiments, and can be varied according to the practical requirements.

In some embodiments, the control unit 4 of the three-phase LLC power conversion circuit can perform at least one of the aforementioned control methods. The control unit 4 can be preset by the user to perform at least one of the aforementioned control methods according to the practical requirements.

In order to improve the three-phase transformer (e.g., the three-phase transformer T shown in FIG. 2) and the three-phase resonant inductor (e.g., the second inductor shown in FIG. 2) in the three-phase LLC power conversion circuit of the above-mentioned embodiments, the magnetic flux of the resonant elements RE_A2, RE_B2, RE_C2is cancelled out to improve the core loss and reduce the volume. In the present disclosure, the three-phase transformer is matched with the resonant inductor in the resonant element to achieve the magnetic flux cancellation, thereby achieving the above purposes. Different implementations of arrangement positions of the three-phase transformer and the three-phase resonant inductor in the three-phase LLC power conversion circuit are illustrated in the following. The marks of A, B, C in the following descriptions represent a first phase A, a second phase B, and a third phase C of the three phases, respectively. The first phase A is 120 degrees leading to the second phase B, the second phase B is 120 degrees leading to the third phase B, and the third phase C is 120 degrees leading to the first phase A.

Please refer to FIG. 15A, FIG. 15B and FIG. 15C. FIG. 15A is a circuit diagram of a magnetic component for a three-phase LLC power conversion circuit according to a first embodiment of the present disclosure. FIG. 15B is a schematic diagram showing the arrangement positions of the three-phase transformer and the three-phase resonant inductor of the magnetic component shown in FIG. 15A. FIG. 15C is a schematic diagram showing a partial magnetic flux vector of the magnetic component shown in FIG. 15B. In the embodiment, the magnetic component 5 includes a three-phase transformer, a three-phase resonant inductor and a magnetic core set. The magnetic core set includes a single magnetic core 6. The three-phase transformer includes a first transformer T_A, a second transformer T_Band a third transformer T_C. The primary windings of the first transformer T_A, the second transformer T_Band the third transformer T_Care star-connected (i.e., Y-connected). The three-phase resonant inductor includes a first resonant inductor L_rBC(BC phase inductor), a second resonant inductor L_rCA(CA phase inductor) and a third resonant inductor L_rAB(AB phase inductor), which are respectively electrically connected to the primary windings of the corresponding transformers in the first transformer T_A, the second transformer T_Band the third transformer T_C. Furthermore, the first resonant inductor L_rBC, the second resonant inductor L_rCAand the third resonant inductor L_rABare delta-connected in a triangle (i.e., A connection). In some embodiments, the three-phase transformer further includes a first magnetizing inductor L_mA, a second magnetizing inductor L_mBand a third magnetizing inductor L_mC, which are respectively connected in parallel with the primary windings of corresponding transformers in the first transformer T_A, the second transformer T_Band the third transformer T_C.

In the magnetic component 5, the first resonant inductor L_rBC, the second resonant inductor L_rCAand the third resonant inductor L_rABare arranged horizontally adjacent to a first side of the magnetic core 6, and the first transformer T_A, the second transformer T_Band the third transformer T_Care horizontally disposed close to a second side of the magnetic core 6. The first side is opposite to the second side. In addition, when the ratio of the inductance of the resonant inductor to the inductance of the corresponding magnetizing inductor is greater than a set value, such as 10, the resonant inductor and the transformer located of different phases are disposed close to each other. That is, the first transformer T_Ais disposed horizontally adjacent to the first resonant inductor L_rBC, the second transformer T_Bis disposed horizontally adjacent to the second resonant inductor L_rCA, and the third transformer T_Cis disposed horizontally adjacent to the third resonant inductor L_rAB. In addition, the phase angle between the magnetic flux direction of the adjacent resonant inductor and the magnetic flux direction of the transformer is greater than 90 degrees and less than 270 degrees. Since the resonant inductor and the transformer disposed side-by-side are arranged horizontally, the winding direction of the resonant inductor is opposite to the winding direction of the adjacent transformer.

In FIG. 15C, it shows the magnetic fluxes Φ_LrBC, Φ_LrCA, Φ_LrABof the first resonant inductor L_rBC, the second resonant inductor L_rCAand the third resonant inductor L_rAB, respectively, shows the magnetic fluxes Φ_mA, Φ_mB, Φ_mCof the first transformer T_A, the second transformer T_Band the third transformer T_C, and also shows the magnetic fluxes Φ_LrA, Φ_LrB, Φ_LrCof the resonant inductor in phase A, phase B and phase C, respectively. By configuring the arrangement positions of the first transformer T_A, the second transformer T_Band the third transformer T_C, and the arrangement positions of the first resonant inductor L_rBC, the second resonant inductor L_rCAand the third resonant inductor L_rAB, the resonant inductor and the transformer disposed side-by-side can achieve magnetic flux cancellation. For example, the magnetic flux of the first transformer T_Ais partially cancelled out by the magnetic flux of the first resonant inductor L_rBCto form the total magnetic flux Φ_ΣAof the A phase, thereby improving the loss of the magnetic core 6 and reducing the volume of the magnetic core 6.

Please refer to FIG. 16A and FIG. 16B. FIG. 16A is a schematic diagram showing another example of the arrangement positions of the three-phase transformer and the three-phase resonant inductor of the magnetic component shown in FIG. 15A. FIG. 16B is a schematic diagram showing a partial magnetic flux vector of the magnetic component shown in FIG. 16A. In some embodiments, when the ratio of the inductance of the resonant inductor to the inductance of the corresponding magnetizing inductor is less than a set value, the resonant inductor and the transformer of the same phase are disposed close to each other. That is, the first transformer T_Ais arranged horizontally adjacent to the second resonant inductor L_rCA, the second transformer T_Bis arranged horizontally adjacent to the third resonant inductor L_rAB, and the third transformer T_Cis arranged horizontally adjacent to the first resonant inductor L_rBC. In addition, the phase angle between the magnetic flux direction of the resonant inductor and the magnetic flux direction of the adjacent transformer arranged is greater than 90 degrees and less than 270 degrees. Since the resonant inductor and the transformer disposed side-by-side are arranged horizontally, the winding direction of the resonant inductor is opposite to the winding direction of the adjacent transformer.

Please refer to FIG. 17A, FIG. 17B, FIG. 17C and FIG. 17D. FIG. 17A is a circuit diagram of a magnetic component for a three-phase LLC power conversion circuit according to a second embodiment of the present disclosure. FIG. 17B is a circuit diagram of a magnetic component for a three-phase LLC power conversion circuit according to a third embodiment of the present disclosure. FIG. 17C is a schematic diagram showing the arrangement positions of the three-phase transformer and the three-phase resonant inductor of the magnetic component shown in FIG. 17A or FIG. 17B. FIG. 17D is a schematic diagram showing a partial magnetic flux vector of the magnetic component shown in FIG. 17C. In the magnetic component 5a shown in FIG. 17A, the primary windings of the first transformer T_A, the second transformer T_Band the third transformer T_Cof the three-phase transformer are star-connected (i.e., Y-connected). The first resonant inductor L_rA, the second resonant inductor L_rBand the third resonant inductor L_rCof the three-phase resonant inductor are electrically connected to the primary windings of the corresponding transformers in the first transformer T_A, the second transformer T_Band the third transformer T_Crespectively. Furthermore, the first resonant inductor L_rA, the second resonant inductor LIB and the third resonant inductor L_rCare star-connected (i.e., Y-connected).

In the magnetic component 5b shown in FIG. 17B, the first transformer T_A, the second transformer T_Band the third transformer T_Cof the three-phase transformer are independent and have a phase difference of 120 degrees. The first resonant inductor L_rA, the second resonant inductor L_rBand the third resonant inductor L_rCof the three-phase resonant inductor are independent and have a phase difference of 120 degrees. The first resonant inductor L_rA, the second resonant inductor LIB and the third resonant inductor L_rCare electrically connected to the primary windings of the corresponding transformers in the first transformer T_A, the second transformer T_Band the third transformer T_C, respectively.

In the magnetic component 5a or the magnetic component 5b, the first resonant inductor L_rA, the second resonant inductor L_rBand the third resonant inductor L_rCare arranged horizontally adjacent to a first side of the magnetic core 6, and the first transformer T_A, the second transformer T_Band the third transformer T_Care arranged horizontally adjacent to a second side of the magnetic core 6. The first side is opposite to the second side, and the resonant inductor and the transformer of different phases are disposed close to each other. That is, the first transformer T_Ais disposed horizontally adjacent to the third resonant inductor L_rC, the second transformer T_Bis disposed horizontally adjacent to the first resonant inductor L_rA, and the third transformer T_Cis disposed horizontally adjacent to the second resonant inductor L_rB. In addition, the phase angle between the magnetic flux direction of the adjacent resonant inductor and the magnetic flux direction of the transformer is greater than 90 degrees and less than 270 degrees. Since the resonant inductor and the transformer disposed side-by-side are arranged horizontally, the winding direction of the adjacent resonant inductor is opposite to the winding direction of the transformer.

In FIG. 17D, it shows the magnetic fluxes Φ_LrA, Φ_LrB, Φ_LrCof the first resonant inductor L_rA, the second resonant inductor L_rBand the third resonant inductor L_rC, respectively, and also shows the magnetic fluxes Φ_mA, Φ_mB, Φ_mCof the first transformer T_A, the second transformer T_Band the third transformer T_C. By configuring the arrangement positions of the first transformer T_A, the second transformer T_Band the third transformer T_C, and the arrangement positions of the first resonant inductor L_rA, the second resonant inductor LIB and the third resonant inductor L_rC, the resonant inductor and the transformer disposed side-by-side can achieve magnetic flux cancellation. For example, the magnetic flux of the first transformer T_Ais partially cancelled out by the magnetic flux of the third resonant inductor L_rCto form the total magnetic flux Φ_ΣAof the A phase, thereby improving the loss of the magnetic core 6 and reducing the volume of the magnetic core 6.

Please refer to FIG. 18A and FIG. 18B. FIG. 18A is a schematic diagram showing another example of the arrangement positions of the three-phase transformer and the three-phase resonant inductor of the magnetic component shown in FIG. 17A or FIG. 17B. FIG. 18B is a schematic diagram showing a partial magnetic flux vector of the magnetic component shown in FIG. 18A. In some embodiments, the resonant inductor and the transformer of the same phase are disposed close to each other. That is, the first transformer T_Aand the first resonant inductor L_rAare arranged horizontally side-by-side. The second transformer T_Bis adjacent to the second resonant inductor L_rB. The third transformer T_Cis arranged horizontally adjacent to the third resonant inductor L_rC. In addition, the phase angle between the magnetic flux direction of the resonant inductor and the magnetic flux direction of the adjacent transformer is greater than 90 degrees and less than 270 degrees. Since the resonant inductor and the transformer disposed side-by-side are arranged horizontally, the winding direction of the resonant inductor is opposite to the winding direction of the adjacent transformer.

Please refer to FIG. 19A, FIG. 19B and FIG. 19C. FIG. 19A is a circuit diagram of a magnetic component for a three-phase LLC power conversion circuit according to a fourth embodiment of the present disclosure. FIG. 19B is a schematic diagram showing the arrangement positions of the three-phase transformer and the three-phase resonant inductor of the magnetic component shown in FIG. 19A. FIG. 19C is a schematic diagram showing a partial magnetic flux vector of the magnetic component shown in FIG. 19B. In the embodiment, the magnetic component 5c includes a three-phase transformer, a three-phase resonant inductor and a magnetic core 6. The three-phase transformer includes a first transformer T_AB, a second transformer T_BCand a third transformer T_CA. The primary windings of the first transformer T_AB, the second transformer T_BCand the third transformer T_CAare delta-connected in a triangle (i.e., Δ connection). The three-phase resonant inductor includes a first resonant inductor L_rA, a second resonant inductor L_rBand a third resonant inductor L_rC, which are respectively electrically connected to the primary windings of the corresponding two transformers in the first transformer T_AB, the second transformer T_BCand the third transformer T_CA. Furthermore, the first resonant inductor L_rA, the second resonant inductor L_rBand the third resonant inductor L_rCare star-connected (i.e., Y-connected). In some embodiments, the three-phase transformer further includes a first magnetizing inductor L_mAB, a second magnetizing inductor L_mBCand a third magnetizing inductor L_mCA, which are respectively connected in parallel with the primary windings of corresponding transformers in the first transformer T_AB, the second transformer T_BCand the third transformer T_CA.

In the magnetic component 5c, the first resonant inductor L_rA, the second resonant inductor L_rBand the third resonant inductor L_rCare arranged horizontally adjacent to a first side of the magnetic core 6, and the first transformer T_AB, the second transformer T_BCand the third transformer T_CAare horizontally disposed close to a second side of the magnetic core 6. The first side is opposite to the second side. In the embodiment, the resonant inductor and the transformer of different phases are disposed close to each other. That is, the first transformer T_ABand the third resonant inductor L_rCare arranged horizontally and disposed side-by-side. The second transformer T_BCis arranged horizontally adjacent to the first resonant inductor L_rA. The third transformer T_CAis arranged horizontally adjacent to the second resonant inductor L_rB. In addition, the phase angle between the magnetic flux direction of the adjacent resonant inductor and the magnetic flux direction of the transformer is greater than 90 degrees and less than 270 degrees. Since the resonant inductor and the transformer disposed side-by-side are arranged horizontally, the winding direction of the adjacent resonant inductor is opposite to the winding direction of the transformer.

In FIG. 19C, it shows the magnetic fluxes Φ_LrA, Φ_LrB, Φ_LrCof the first resonant inductor L_rA, the second resonant inductor L_rBand the third resonant inductor L_rC, respectively, shows the magnetic fluxes Φ_mAB, Φ_mBC, Φ_mCAof the first transformer T_AB, the second transformer T_BCand the third transformer T_CA, and also shows the magnetic fluxes Φ_LrAB, Φ_LrBC, Φ_LrCAof the resonant inductor in phase AB, phase BC and phase CA, respectively. By configuring the arrangement positions of the first transformer T_AB, the second transformer T_BCand the third transformer T_CA, and the arrangement positions of the first resonant inductor L_rA, the second resonant inductor LIB and the third resonant inductor L_rC, the resonant inductor and the transformer disposed side-by-side can achieve magnetic flux cancellation. For example, the magnetic flux of the first transformer T_ABis partially cancelled out by the magnetic flux of the third resonant inductor L_rC, thereby improving the loss of the magnetic core 6 and reducing the volume of the magnetic core 6.

Please refer to FIG. 20A and FIG. 20B. FIG. 20A is a schematic diagram showing another example of the arrangement positions of the three-phase transformer and the three-phase resonant inductor of the magnetic component shown in FIG. 19A. FIG. 20B is a schematic diagram showing a partial magnetic flux vector of the magnetic component shown in FIG. 20A. In some embodiments, the resonant inductor and the transformer of the same phase are disposed close to each other. That is, the first transformer T_ABand the first resonant inductor L_rAare arranged horizontally and disposed side-by-side. The second transformer T_BCis arranged horizontally adjacent to the second resonant inductor L_rB. The third transformer T_CAis arranged horizontally adjacent to the third resonant inductor L_rC. In addition, the phase angle between the magnetic flux direction of the resonant inductor and the magnetic flux direction of the adjacent transformer is greater than 90 degrees and less than 270 degrees. Since the resonant inductor and the transformer disposed side-by-side are arranged horizontally, the winding direction of the resonant inductor is opposite to the winding direction of the adjacent transformer.

Please refer to FIG. 21A, FIG. 21B and FIG. 21C. FIG. 21A is a circuit diagram of a magnetic component for a three-phase LLC power conversion circuit according to a fifth embodiment of the present disclosure. FIG. 21B is a schematic diagram showing the arrangement positions of the three-phase transformer and the three-phase resonant inductor of the magnetic component shown in FIG. 21A. FIG. 21C is a schematic diagram showing a partial magnetic flux vector of the magnetic component shown in FIG. 21B. In the embodiment, the magnetic component 5d includes a three-phase transformer, a three-phase resonant inductor and a magnetic core 6. The three-phase transformer includes a first transformer T_AB, a second transformer T_BCand a third transformer T_CA. The primary windings of the first transformer T_AB, the second transformer T_BCand the third transformer T_CAare delta-connected in a triangle (i.e., Δ connection). The three-phase resonant inductor includes a first resonant inductor L_rBA, a second resonant inductor L_rCAand a third resonant inductor L_rAB, which are respectively electrically connected to the primary windings of the corresponding two transformers in the first transformer T_AB, the second transformer T_BCand the third transformer T_CA. Furthermore, the first resonant inductor L_rBC, the second resonant inductor L_rCAand the third resonant inductor L_rABare delta-connected in a triangle (i.e., Δ connection). In some embodiments, the three-phase transformer further includes a first magnetizing inductor L_mAB, a second magnetizing inductor L_mBCand a third magnetizing inductor L_mCA, which are respectively connected in parallel with the primary windings of corresponding transformers in the first transformer T_AB, the second transformer T_BCand the third transformer T_CA.

In the magnetic component 5d, the first resonant inductor L_rBC, the second resonant inductor L_rCAand the third resonant inductor L_rABare arranged horizontally adjacent to a first side of the magnetic core 6, and the first transformer T_AB, the second transformer T_BCand the third transformer T_CAare horizontally disposed close to a second side of the magnetic core 6. The first side is opposite to the second side. In the embodiment, the resonant inductor and the transformer of different phases are disposed close to each other. That is, the first transformer T_ABand the second resonant inductor L_rCAare arranged horizontally and disposed side-by-side. The second transformer T_BCis arranged horizontally adjacent to the third resonant inductor L_rAB. The third transformer T_CAis arranged horizontally adjacent to the first resonant inductor L_rBC. In addition, the phase angle between the magnetic flux direction of the adjacent resonant inductor and the magnetic flux direction of the transformer is greater than 90 degrees and less than 270 degrees. Since the resonant inductor and the transformer disposed side-by-side are arranged horizontally, the winding direction of the adjacent resonant inductor is opposite to the winding direction of the transformer.

In FIG. 21C, it shows the magnetic fluxes Φ_LrAB, Φ_LrBC, Φ_LrCAof the third resonant inductor L_rAB, the first resonant inductor L_rBCand the second resonant inductor L_rCA, respectively, and also shows the magnetic fluxes Φ_mAB, Φ_mBC, Φ_mCAof the first transformer T_AB, the second transformer T_BCand the third transformer T_CA. By configuring the arrangement positions of the first transformer T_AB, the second transformer T_BCand the third transformer T_CA, and the arrangement positions of the third resonant inductor L_rAB, the first resonant inductor L_rBCand the second resonant inductor L_rCA, the resonant inductor and the transformer disposed side-by-side can achieve magnetic flux cancellation. For example, the magnetic flux of the first transformer T_ABis partially cancelled out by the magnetic flux of the second resonant inductor L_rCA, thereby improving the loss of the magnetic core 6 and reducing the volume of the magnetic core 6.

Please refer to FIG. 22A and FIG. 22B. FIG. 22A is a schematic diagram showing another example of the arrangement positions of the three-phase transformer and the three-phase resonant inductor of the magnetic component shown in FIG. 21A. FIG. 22B is a schematic diagram showing a partial magnetic flux vector of the magnetic component shown in FIG. 22A. In some embodiments, the resonant inductor and the transformer of the same phase are disposed close to each other. That is, the first transformer T_ABand the third resonant inductor L_rABare arranged horizontally and disposed side-by-side. The second transformer T_BCis adjacent to the first resonant inductor L_rBC. The third transformer T_CAis arranged horizontally adjacent to the second resonant inductor L_rCA. In addition, the phase angle between the magnetic flux direction of the resonant inductor and the magnetic flux direction of the adjacent transformer is greater than 90 degrees and less than 270 degrees. Since the resonant inductor and the transformer disposed side-by-side are arranged horizontally, the winding direction of the resonant inductor is opposite to the winding direction of the adjacent transformer.

Please refer to FIG. 23A, FIG. 23B, FIG. 23C, FIG. 23D, FIG. 23E and FIG. 23F. FIG. 23A is a circuit diagram of a magnetic component for a three-phase LLC power conversion circuit according to a sixth embodiment of the present disclosure. FIG. 23B is a circuit diagram of a magnetic component for a three-phase LLC power conversion circuit according to a seven embodiment of the present disclosure. FIG. 23C is a circuit diagram of a magnetic component for a three-phase LLC power conversion circuit according to an eighth embodiment of the present disclosure. FIG. 23D is a circuit diagram of a magnetic component for a three-phase LLC power conversion circuit according to a ninth embodiment of the present disclosure. FIG. 23E is a schematic diagram showing the arrangement positions of the three-phase transformer and the three-phase resonant inductor of the magnetic component shown in FIG. 23A, FIG. 23B, FIG. 23C or FIG. 23D. FIG. 23F is a schematic diagram showing a partial magnetic flux vector of the magnetic component shown in FIG. 23E. The magnetic component 5e shown in FIG. 23A includes a three-phase transformer, a first three-phase resonant inductor, a second three-phase resonant inductor and a magnetic core 6. The primary windings of the first transformer T_A, the second transformer T_Band the third transformer T_Cof the three-phase transformer are star-connected (i.e., Y-connected). The secondary windings of the first transformer T_A, the second transformer T_Band the third transformer T_Cof the three-phase transformer are star-connected (i.e., Y-connected). The first three-phase resonant inductor includes a first resonant inductor L_rA1, a second resonant inductor L_rB1and a third resonant inductor L_rC1. The first resonant inductor L_rA1, the second resonant inductor L_rB1and the third resonant inductor L_rC1are electrically connected to the primary windings of the corresponding transformers in the first transformer T_Athe second transformer T_Band the third transformer T_C, respectively, and the first resonant inductor LAI, the second resonant inductor L_rB1and the third resonant inductor L_rC1are star-connected (i.e., Y-connected). The second three-phase resonant inductor includes a fourth resonant inductor L_rA2, a fifth resonant inductor L_rB2and a sixth resonant inductor L_rC2. The fourth resonant inductor L_rA2, the fifth resonant inductor L_rB2and the sixth resonant inductor L_rC2are electrically connected to the secondary windings of the corresponding transformers in the first transformer T_A, the second transformer T_Band the third transformer T_C, respectively. Furthermore, the fourth resonant inductor L_rA2, the fifth resonant inductor L_rB2and the sixth resonant inductor L_rC2are star-connected (i.e., Y-connected).

In the magnetic component 5f shown in FIG. 23B, the first transformer T_A, the second transformer T_Band the third transformer T_Cof the three-phase transformer are independent and have a phase difference of 120 degrees. The first resonant inductor L_rA1, the second resonant inductor L_rB1and the third resonant inductor L_rC1of the first three-phase resonant inductor are independent and have a phase difference of 120 degrees. Moreover, the first resonant inductor L_rA1, the second resonant inductor L_rB1and the third resonant inductor L_rC1are electrically connected to the primary windings of the corresponding transformers in the first transformer T_A, the second transformer T_Band the third transformer T_C, respectively. The fourth resonant inductor L_rA2, the fifth resonant inductor L_rB2and the sixth resonant inductor L_rC2of the second three-phase resonant inductor are independent and have a phase difference of 120 degrees. The fourth resonant inductor L_rA2, the fifth resonant inductor L_rB2and the sixth resonant inductor L_rC2are electrically connected to the secondary windings of the corresponding transformers in the first transformer T_A, the second transformer T_Band the third transformer T_C, respectively.

In the magnetic component 5g shown in FIG. 23C, the magnetic component 5g includes a three-phase transformer, a first three-phase resonant inductor, a second three-phase resonant inductor and a magnetic core 6. The primary windings of the first transformer T_A, the second transformer T_Band the third transformer T_Cof the three-phase transformer are star-connected (i.e., Y-connected). The first three-phase resonant inductor includes a first resonant inductor L_rA1, a second resonant inductor L_rB1and a third resonant inductor L_rC1. The first resonant inductor L_rA1, the second resonant inductor L_rB1and the third resonant inductor L_rC1are electrically connected to the primary windings of the corresponding transformers in the first transformer T_A, the second transformer T_Band the third transformer T_C, respectively. Furthermore, the first resonant inductor L_rA1, the second resonant inductor L_rB1, and the third resonant inductor L_rC1are star-connected (i.e., Y-connected). The second three-phase resonant inductor includes a fourth resonant inductor L_rA2, a fifth resonant inductor L_rB2and a sixth resonant inductor L_rC2. The fourth resonant inductor L_rA2, the fifth resonant inductor L_rB2and the sixth resonant inductor L_rC2are electrically connected between the corresponding one of the first resonant inductor L_rA1, the second resonant inductor L_rB1and the third resonant inductor L_rC1and the primary windings of the corresponding one of the first transformer T_A, the second transformer T_Band the third transformer T_C. Furthermore, the fourth resonant inductor L_rA2, the fifth resonant inductor L_rB2and the sixth resonant inductor L_rC2are star-connected (i.e., Y-connected).

In the magnetic component 5h shown in FIG. 23D, the first transformer T