Magnetic component for three-phase llc power conversion circuit

Abstract

This case discloses a magnetic component suitable for a three-phase LLC power conversion circuit, comprising a magnetic core assembly, a three-phase transformer, and a three-phase resonant inductor. The three-phase transformer comprises three transformers. The three-phase resonant inductor comprises three resonant inductors, each electrically connected to the primary winding of its corresponding transformer. The three transformers and three resonant inductors are mounted on the magnetic core assembly, and the primary windings of the three transformers are connected in a star, delta, or independent configuration, each 120 degrees out of phase. The three resonant inductors are also connected in a star, delta, or independent configuration, each 120 degrees out of phase. The resonant inductors in the same phase or different phases are adjacent to the transformers, and the phase angle between the magnetic flux direction of the adjacent resonant inductors and the magnetic flux direction of the transformers is greater than 90 degrees and less than 270 degrees, or between -90 degrees and +90 degrees.

Description

Technical Field

[0001] This case pertains to the field of power conversion circuits, and more particularly to a magnetic component suitable for three-phase power conversion circuits. Prior Technology

[0002] With the rapid development of information technology, especially cloud computing, big data, and artificial intelligence, the energy consumption of data centers is increasing. Therefore, the power rating and power density of power conversion circuits supplying power to data centers are also significantly increasing. Compared to single-phase power conversion circuits, three-phase LLC power conversion circuits have lower RMS current, lower peak current, and better magnetic integration, and are therefore widely used in data centers.

[0003] However, the control of three-phase LLC power conversion circuits is more complex than that of unidirectional power conversion circuits due to the interaction between the three phases. For example, in unidirectional power conversion circuits, phase shift control can be used to narrow the switching frequency range, making the circuit suitable for wide voltage range applications. However, in three-phase LLC power conversion circuits, which have two control variables, the single control variable of phase shift control cannot effectively address the change in resonant frequency. This would result in significant reactive current and make it impossible to accurately control the switch for soft switching. Therefore, there are still areas for improvement in the control of three-phase LLC power conversion circuits.

[0004] Furthermore, three-phase LLC power conversion circuits typically include a three-phase transformer and a three-phase inductor. To reduce core and copper losses, the three-phase inductor and transformer are usually integrated into a single magnetic component. However, current conventional magnetic components that integrate three-phase inductors and transformers still have room for improvement in terms of core losses and size reduction due to poor flux cancellation.

[0005] Therefore, it is necessary to develop a magnetic component suitable for three-phase power conversion circuits to solve the problems and deficiencies faced by existing technologies. Summary of the Invention

[0006] The purpose of this invention is to provide a magnetic component suitable for three-phase power conversion circuits, in order to solve the shortcomings of traditional magnetic components, such as high core loss and large size due to poor flux cancellation of three-phase inductors and three-phase transformers.

[0007] To achieve the above objectives, a preferred embodiment of this invention is a magnetic component suitable for a three-phase LLC power conversion circuit, comprising: a magnetic core assembly including at least one magnetic core; a three-phase transformer including three transformers respectively applied to the first, second, and third phases of the three phases; and a first group of three-phase resonant inductors including three resonant inductors respectively applied to the first, second, and third phases, wherein each resonant inductor is electrically connected to the primary winding of the corresponding at least one transformer; wherein the three transformers and the three first resonant inductors are disposed on the magnetic core assembly, and the primary windings of the three transformers are star-connected, delta-connected, or independent and are 120 degrees apart, and the three first resonant inductors are star-connected, delta-connected, or independent and are 120 degrees apart, and the resonant inductors in the same phase or different phases are adjacent to the transformers, and the phase angle between the magnetic flux direction of the adjacent resonant inductors and the magnetic flux direction of the transformers is greater than 90 degrees and less than 270 degrees or between -90 degrees and +90 degrees. Simple Explanation of the Diagram

[0008] Figure 1 is a schematic flowchart of the control method according to an embodiment of this case.

[0009] Figure 2 is a circuit topology diagram of a first embodiment of a three-phase LLC power conversion circuit to which the control method shown in Figure 1 is applicable.

[0010] Figures 3 through 6 are schematic diagrams of partial waveform timing of the three-phase LLC power conversion circuit when the control unit of the three-phase LLC power conversion circuit shown in Figure 2 is controlled under different implementation states.

[0011] Figure 7 is a circuit topology diagram of the second embodiment of the three-phase LLC power conversion circuit in this case.

[0012] Figure 8 is a circuit topology diagram of the third embodiment of the three-phase LLC power conversion circuit in this case.

[0013] Figure 9 is the circuit topology diagram of the fourth embodiment of the three-phase LLC power conversion circuit in this case.

[0014] Figures 10 and 11 are schematic diagrams of partial waveforms and timing of the three-phase LLC power conversion circuit when the control unit of the three-phase LLC power conversion circuit shown in Figure 9 is controlled under different implementation states.

[0015] Figure 12 is a circuit topology diagram of the fifth embodiment of the three-phase LLC power conversion circuit in this case.

[0016] Figure 13 is a waveform timing diagram of the control unit of the three-phase LLC power conversion circuit shown in Figure 12 during operation.

[0017] Figure 14 is a circuit topology diagram of the sixth embodiment of the three-phase LLC power conversion circuit in this case.

[0018] Figure 15A is a circuit topology diagram of a first embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit in this case.

[0019] Figure 15B is a schematic diagram showing the placement of the three-phase transformer and three-phase resonant inductor of the magnetic assembly shown in Figure 15A.

[0020] Figure 15C is a schematic diagram of a portion of the magnetic flux vector of the magnetic component shown in Figure 15B.

[0021] Figure 16A is a schematic diagram showing another variation of the placement of the three-phase transformer and three-phase resonant inductor in the magnetic assembly shown in Figure 15A.

[0022] Figure 16B is a schematic diagram of a portion of the magnetic flux vector of the magnetic component shown in Figure 16A.

[0023] Figure 17A is a circuit topology diagram of a second embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit in this invention.

[0024] Figure 17B is a circuit topology diagram of a third embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit in this invention.

[0025] Figure 17C is a schematic diagram showing the placement of the three-phase transformer and three-phase resonant inductor of the magnetic assembly shown in Figure 17A or Figure 17B.

[0026] Figure 17D is a schematic diagram of a portion of the magnetic flux vector of the magnetic component shown in Figure 17C.

[0027] Figure 18A is a schematic diagram of another variation of the placement of the three-phase transformer and three-phase resonant inductor in the magnetic components shown in Figure 17A or Figure 17B.

[0028] Figure 18B is a schematic diagram of a portion of the magnetic flux vector of the magnetic component shown in Figure 18A.

[0029] Figure 19A is a circuit topology diagram of a fourth embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit in this invention.

[0030] Figure 19B is a schematic diagram showing the placement of the three-phase transformer and three-phase resonant inductor of the magnetic assembly shown in Figure 19A.

[0031] Figure 19C is a schematic diagram of a portion of the magnetic flux vector of the magnetic component shown in Figure 19B.

[0032] Figure 20A is a schematic diagram showing another variation of the placement of the three-phase transformer and three-phase resonant inductor in the magnetic assembly shown in Figure 19A.

[0033] Figure 20B is a schematic diagram of a portion of the magnetic flux vector of the magnetic component shown in Figure 20A.

[0034] Figure 21A is a circuit topology diagram of the fifth embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit in this case.

[0035] Figure 21B is a schematic diagram showing the placement of the three-phase transformer and three-phase resonant inductor of the magnetic components shown in Figure 21A.

[0036] Figure 21C is a schematic diagram of a portion of the magnetic flux vector of the magnetic component shown in Figure 21B.

[0037] Figure 22A is a schematic diagram showing another variation of the placement of the three-phase transformer and three-phase resonant inductor in the magnetic components shown in Figure 21A.

[0038] Figure 22B is a schematic diagram of a portion of the magnetic flux vector of the magnetic component shown in Figure 22A.

[0039] Figure 23A is a circuit topology diagram of the sixth embodiment of the magnetic component applicable to the three-phase LLC power conversion circuit of this invention.

[0040] Figure 23B is a circuit topology diagram of the seventh embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit in this case.

[0041] Figure 23C is a circuit topology diagram of the eighth embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit in this case.

[0042] Figure 23D is a circuit topology diagram of the ninth embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit in this case.

[0043] Figure 23E is a schematic diagram showing the placement of the three-phase transformer and three-phase resonant inductor of the magnetic components shown in Figures 23A, 23B, 23C, or 23D.

[0044] Figure 23F is a schematic diagram of a portion of the magnetic flux vector of the magnetic component shown in Figure 23E.

[0045] Figure 24 is a schematic diagram showing another variation of the placement of the three-phase transformer and three-phase resonant inductor in the magnetic assembly shown in Figure 15A.

[0046] Figure 25 is a schematic diagram of another variation of the placement of the three-phase transformer and three-phase resonant inductor of the magnetic components shown in Figure 23E. Implementation

[0047] Some typical embodiments that embody the features and advantages of this case will be described in detail in the following description. It should be understood that this case can have various variations in different forms, all of which do not depart from the scope of this case, and the descriptions and drawings therein are essentially for illustrative purposes and not for limiting this case.

[0048] Figure 1 is a flowchart illustrating the steps of a control method according to an embodiment of this invention. Figure 2 is a circuit topology diagram of a first embodiment of a three-phase LLC power conversion circuit to which the control method shown in Figure 1 is applicable. Figures 3 to 6 are schematic diagrams of partial waveform timing of the three-phase LLC power conversion circuit when the control unit of the three-phase LLC power conversion circuit shown in Figure 2 is controlled under different implementations. As shown in Figures 1, 2, 3, 4, 5, and 6, in this embodiment, the control method of this invention can be applied to common three-phase LLC power conversion circuits, or to the three-phase LLC power conversion circuit 1 shown in Figure 2. Since there are various implementations of three-phase LLC power conversion circuits, they cannot all be described in detail. Therefore, the control method of this invention will be described below using the three-phase LLC power conversion circuit 1 shown in Figure 2 as an exemplary embodiment. The input terminal of the three-phase LLC power conversion circuit 1 is electrically connected to the input power supply DC to receive the input voltage Vin, and the output terminal of the three-phase LLC power conversion circuit 1 is electrically connected to the load R to provide the output voltage Vo to the load R. The three-phase LLC power conversion circuit 1 includes a three-phase transformer T, an input switch group 2, an output switch group 3, a control unit 4, and a resonant circuit group.

[0049] Input switch group 2 is electrically connected to the input terminal of the three-phase LLC power conversion circuit 1, and includes a first upper input switch Q1, a first lower input switch Q2, a second upper input switch Q3, a second lower input switch Q4, a third upper input switch Q5, and a third lower input switch Q6. The first upper input switch Q1 and the first lower input switch Q2 are connected in series to form the first input switch bridge arm, and they share a first contact. The second upper input switch Q3 and the second lower input switch Q4 are connected in series to form the second input switch bridge arm, and they share a second contact. The third upper input switch Q5 and the third lower input switch Q6 are connected in series to form the third input switch bridge arm, and they share a third contact. Furthermore, the first, second, and third input switch bridge arms are connected in parallel with each other.

[0050] The three-phase transformer T includes a first transformer T1, a second transformer T2, and a third transformer T3. Each of the first transformer T1, second transformer T2, and third transformer T3 includes a primary winding and a secondary winding. In some embodiments, the first transformer T1, second transformer T2, and third transformer T3 respectively include magnetizing inductors Lm1, Lm2, and Lm3, which are connected in parallel with the primary windings of the first transformer T1, second transformer T2, and third transformer T3, respectively.

[0051] The resonant circuit group is electrically connected between the input switch group 2 and a plurality of primary windings of the three-phase transformer T, and includes a plurality of first resonant elements RE A1, RE B1, RE C1 and a plurality of second resonant elements RE A2, RE B2, RE C2. The plurality of first resonant elements RE A1, RE B1, RE C1 are star-connected (i.e., Y-connected) and can be composed of inductors or capacitors respectively. The first resonant element RE A1 is electrically connected between the first contact and the first end of the primary winding of the first transformer T1, the first resonant element RE B1 is electrically connected between the second contact and the first end of the primary winding of the second transformer T2, and the first resonant element RE C1 is electrically connected between the third contact and the first end of the primary winding of the third transformer T3. The plurality of second resonant elements RE A2, RE B2, and RE C2 are connected in a delta configuration (Δ connection) and are each composed of inductors. The endpoints of any two second resonant elements are electrically connected to each other and to the second terminal of the primary winding of the corresponding transformer in the first transformer T1, second transformer T2, or third transformer T3. Because the plurality of second resonant elements RE A2, RE B2, and RE C2 are connected in a delta configuration (Δ connection) and are each composed of inductors, the inductance of the second resonant elements RE A2, RE B2, and RE C2 is increased by three times compared to the star connection configuration, while the current is reduced compared to the star connection configuration. The conductor cross-sectional area is reduced by three times compared to the star connection, while the number of winding turns only increases by a factor of two. The loss and volume remain the same compared to a star connection. In some embodiments, the plurality of second resonant elements RE A2, RE B2, RE C2 may also be composed of capacitors.

[0052] Output switch group 3 is electrically connected between the plurality of secondary windings of the three-phase transformer T and the output terminal of the three-phase LLC power conversion circuit 1. Output switch group 3 includes a first synchronous rectifier switch group, a second synchronous rectifier switch group, and a third synchronous rectifier switch group, which are respectively coupled to the secondary windings of the corresponding transformers in the first transformer T1, the second transformer T2, and the third transformer T3. In some embodiments, the first synchronous rectifier switch group includes a first upper rectifier switch SR1, a first lower rectifier switch SR2, a second upper rectifier switch SR3, and a second lower rectifier switch SR4. The first upper rectifier switch SR1 and the first lower rectifier switch SR2 are connected in series to form a first rectifier bridge arm, and the second upper rectifier switch SR3 and the second lower rectifier switch SR4 are connected in series to form a second rectifier bridge arm, wherein the first rectifier bridge arm and the second rectifier bridge arm are connected in parallel. The second synchronous rectifier switch group includes a third upper rectifier switch SR5, a third lower rectifier switch SR6, a fourth upper rectifier switch SR7, and a fourth lower rectifier switch SR8. The third upper rectifier switch SR5 and the third lower rectifier switch SR6 are connected in series to form the third rectifier bridge arm, and the fourth upper rectifier switch SR7 and the fourth lower rectifier switch SR8 are connected in series to form the fourth rectifier bridge arm. The third and fourth rectifier bridge arms are connected in parallel. The third synchronous rectifier switch group includes a fifth upper rectifier switch SR9, a fifth lower rectifier switch SR10, a sixth upper rectifier switch SR11, and a sixth lower rectifier switch SR12. The fifth upper rectifier switch SR9 and the fifth lower rectifier switch SR10 are connected in series to form the fifth rectifier bridge arm, and the sixth upper rectifier switch SR11 and the sixth lower rectifier switch SR12 are connected in series to form the sixth rectifier bridge arm. The fifth and sixth rectifier bridge arms are connected in parallel. In other embodiments, the first upper rectifier switch SR1, the first lower rectifier switch SR2, the second upper rectifier switch SR3, the second lower rectifier switch SR4, the third upper rectifier switch SR5, the third lower rectifier switch SR6, the fourth upper rectifier switch SR7 and the fourth lower rectifier switch SR8, the fifth upper rectifier switch SR9, the fifth lower rectifier switch SR10, the sixth upper rectifier switch SR11, and the sixth lower rectifier switch SR12 can all be active switches, such as metal-oxide-semiconductor field-effect transistors. Since the first synchronous rectifier switch group, the second synchronous rectifier switch group, and the third synchronous rectifier switch group of the output switch group 3 of the three-phase LLC power conversion circuit 1 are all full-bridge structures, the voltage stress of each rectifier switch in the first synchronous rectifier switch group, the second synchronous rectifier switch group, and the third synchronous rectifier 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 arm, the first transformer T1, the first resonant element RE A1, the second resonant element RE A2 and the first synchronous rectifier switch group constitute the first phase of the three-phase LLC power conversion circuit 1.The second input switch bridge arm, the second transformer T2, the first resonant element REB1, the second resonant element REB2, and the second synchronous rectifier switch group constitute the second phase of the three-phase LLC power conversion circuit 1. The third input switch bridge arm, the third transformer T3, the first resonant element REC1, the second resonant element REC2, and the third synchronous rectifier switch group constitute the third phase of the three-phase LLC power conversion circuit 1.

[0053] Control unit 4 is electrically connected to input switch group 2 and output switch group 3 to detect the zero-crossing point of input voltage Vin, output voltage Vo, and output current of each phase. Based on the detection results, it controls the switching operation of the first upper input switch Q1 to the third lower input switch Q6 of input switch group 2, and controls the synchronous rectification switching operation of the first upper rectifier switch SR1 to the sixth lower rectifier switch SR12 of output switch group 3. Preferably, but not limited to, the switching actions of any two upper input switches in input switch group 2 are 120 degrees apart; the switching actions of the upper and lower input switches in each input switch bridge arm of input switch group 2 are complementary and have a dead time; the switching actions of the upper and lower rectifier switches in each rectifier bridge arm of output switch group 3 are complementary and have a dead time. Furthermore, the control unit 4 controls the switching state of at least one rectifier switch in the synchronous rectifier switch group of each phase's output switch group 3 to lead or lag the switching state of the corresponding input switch in the input switch bridge arm of the same phase (i.e., the phase angle of the input switch corresponding to the lead or lag of at least one rectifier switch conduction) based on the ratio of the output voltage Vo to the input voltage Vin, and / or adjusts the duty cycle of all input switches in each input switch bridge arm of the input switch group 2 to increase the ratio of the output voltage Vo to the input voltage Vin. In addition, the control unit 4 adjusts the switching frequency of all input switches in the input switch group 2 based on the output voltage Vo, the reference voltage Vref, and the soft-switching setting conditions, enabling all input switches in the input switch group 2 to perform soft-switching switching.

[0054] Since each phase of the three-phase LLC power conversion circuit 1 operates with a 120-degree phase difference, and the two switches of each phase's switching bridge arm operate complementaryly, Figure 3 only illustrates some operating parameters of the three-phase LLC power conversion circuit 1 to demonstrate the technology of this application. In Figures 3 to 6, symbols Q1, Q3, and Q5 represent the switching states of the first upper input switch Q1, the second upper input switch Q3, and the third upper input switch Q5 in the input switch group 2, respectively. Symbols Q7A and Q8A represent the switching states of the synchronous rectifier switches (i.e., the diagonally opposite first upper rectifier switch SR1 and the second lower rectifier switch SR4) that are in phase with the first upper input switch Q1, respectively. The switching state of the first upper rectifier switch SR1 leads the switching state of the first upper input switch Q1 by a first time ΔT1, and the switching state of the second lower rectifier switch SR4 lags the switching state of the first upper input switch Q1 by a second time ΔT2. Symbols Q9A and Q10A represent the switching states of the synchronous rectifier switches (i.e., the diagonally opposite third upper rectifier switch SR5 and fourth lower rectifier switch SR8) that are in phase with the second upper input switch Q3. The switching state of the third upper rectifier switch SR5 precedes the switching state of the second upper input switch Q3, and the switching state of the fourth lower rectifier switch SR8 lags behind the switching state of the second upper input switch Q3. Symbols Q11A and Q12A represent the switching states of the synchronous rectifier switches (i.e., the diagonally opposite fifth upper rectifier switch SR9 and sixth lower rectifier switch SR12) that are in phase with the third upper input switch Q5. The switching state of the fifth upper rectifier switch SR9 precedes the switching state of the third upper input switch Q5, and the switching state of the sixth lower rectifier switch SR12 lags behind the switching state of the third upper input switch Q5. Ip1 is the current flowing through the primary winding of the first transformer T1 in the first phase of the three-phase LLC power conversion circuit 1, IM1 is the current flowing through the magnetizing inductance Lm1 of the first transformer T1 in the first phase of the three-phase LLC power conversion circuit 1, and Is1 is the current flowing through the secondary winding of the first transformer T1 in the first phase of the three-phase LLC power conversion circuit 1.

[0055] As shown in Figure 3, the control unit 4 controls the switching state of at least one rectifier switch in the synchronous rectifier switch group of each phase's output switch group 3 to lead the switching state of the corresponding input switch in the input switch bridge arm of the same phase, based on the ratio of the output voltage Vo to the input voltage Vin. Furthermore, the control unit 4 controls the switching state of the remaining at least one rectifier switch in the synchronous rectifier switch group of each phase's output switch group 3 to lag the switching state of the corresponding input switch in the input switch bridge arm of the same phase. As shown in Figure 4, the control unit 4 can also be modified to control at least one rectifier switch in the synchronous rectifier switch group of each phase's output switch group 3 to perform synchronous rectification switching, and control the switching state of the remaining at least one rectifier switch in the synchronous rectifier switch group of each phase's output switch group 3 to lag the switching state of the corresponding input switch in the input switch bridge arm of the same phase. As shown in Figures 5 and 6, the control unit 4 can also be modified to control at least one rectifier switch in the synchronous rectifier switch group of each phase's output switch group 3 to perform synchronous rectification switching, and the switching state of the remaining at least one rectifier switch in the synchronous rectifier switch group of each phase's output switch group 3 is ahead of the switching state of the corresponding input switch in the input switch bridge arm of the same phase by a third time ΔT. Furthermore, as shown in Figure 6, the control unit 4 further adjusts the switching frequency of all input switches in the input switch group 2 according to the soft-switching setting conditions, so that all input switches in the input switch group 2 perform soft-switching switching.

[0056] As can be seen from the above, the three-phase LLC power conversion circuit 1 in this case can not only reduce the frequency range of the switch, but also has lower RMS current, peak current and better magnetic integration. Furthermore, because the control unit 4 controls the two control variables of the switch phase and switching frequency, it can solve the problem of increased reactive current due to the change of resonant frequency, and enable the switch to perform soft switching more accurately.

[0057] In some embodiments, the control unit 4 includes a zero-current detection circuit 41, a gain control circuit 42, a first driver 43, a subtractor 44, a compensation circuit 45, a voltage-controlled oscillator 46, and a second driver 47. The first driver 43 is configured to drive the first upper rectifier switch SR1 to the sixth lower rectifier switch SR12 of the output switch group 3. The zero-current detection circuit 41 is electrically connected to the secondary windings of the first transformer T1, the second transformer T2, and the third transformer T3, and is used to detect the zero-crossing point of the output current of each phase of the three-phase LLC power conversion circuit 1. The gain control circuit 42 is configured to detect the input voltage Vin and the output voltage Vo received by the three-phase LLC power conversion circuit 1, and receive the detection results of the zero-current detection circuit 41, and control the first driver 43 to perform synchronous rectification switching operation corresponding to the first upper rectifier switch SR1 to the sixth lower rectifier switch SR12 of the output switch group 3 based on the detection results of the input voltage Vin, the output voltage Vo, and the zero-crossing point of the output current of each phase. The gain control circuit 42 further controls the switching state of at least one rectifier switch in the synchronous rectifier switch group of each phase's output switch group 3 to lead or lag the switching state of the corresponding input switch in the input switch bridge arm of the same phase (i.e., the phase angle of the input switch corresponding to the lead or lag of at least one rectifier switch in conduction) based on the ratio of the output voltage Vo to the input voltage Vin, and / or adjusts the duty cycle of all input switches in each input switch bridge arm of the input switch group 2 to increase, thereby increasing the ratio of the output voltage Vo to the input voltage Vin. The subtractor 44 is configured to perform a subtraction operation between the output voltage Vo and the reference voltage Vref. The compensation circuit 45 is configured to receive the soft-switching setting conditions and the operation result of the subtractor 44, and output a compensation signal based on the soft-switching setting conditions and the operation result of the subtractor 44. The voltage-controlled oscillator 46 generates a switching signal with the frequency of the first upper input switch Q1 to the third lower input switch Q6 based on the compensation signal. The second driver 47 is configured to perform soft switching operation on the first upper input switch Q1 to the third lower input switch Q6 of the input switch group 2 of the output switch group 3 according to the switching signal.

[0058] Please refer to Figure 1 again. The control method in this case includes the following steps.

[0059] Step S1: Control unit 4 detects the input voltage Vin received by the three-phase LLC power conversion circuit 1, the output voltage Vo output by the three-phase LLC power conversion circuit 1, and the zero crossover point of the output current of each phase of the three-phase LLC power conversion circuit.

[0060] In step S2, the control unit 4 controls the switching operation of the first upper input switch Q1 to the third lower input switch Q6 of the input switch group 2 based on the detection results of the input voltage Vin, the output voltage Vo, and the zero-crossing point of the output current of each phase of the three-phase LLC power conversion circuit. It also controls the synchronous rectification switching operation of the first upper rectifier switch SR1 to the sixth lower rectifier switch SR12 of the output switch group 3. Furthermore, based on the ratio of the output voltage Vo to the input voltage Vin, the control unit 4 controls the switching state of at least one rectifier switch in the synchronous rectification switch group of each phase's output switch group 3 to lead or lag the switching state of the corresponding input switch in the same phase's input switch bridge arm, and / or adjusts the duty cycle of all input switches in all input switch bridge arms of each phase's input switch group 2 to increase the ratio of the output voltage Vo to the input voltage Vin. In addition, the control unit 4 adjusts the switching frequency of all input switches in the input switch group 2 based on the output voltage Vo, the reference voltage Vref, and the soft-switching setting conditions, enabling all input switches in the input switch group 2 to perform soft-switching switching.

[0061] Figure 7 is a circuit topology diagram of the second embodiment of the three-phase LLC power conversion circuit of this case. In this embodiment, the circuit structure of the three-phase LLC power conversion circuit 1a is similar to that of the three-phase LLC power conversion circuit 1 shown in Figure 2, so its circuit structure will not be described again. However, in this 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 Q5, and the third lower input switch Q6 in the input switch group 2 of the three-phase LLC power conversion circuit 1a are electrically connected in a cascaded manner.

[0062] Figure 8 is a circuit topology diagram of the third embodiment of the three-phase LLC power conversion circuit of this case. In this embodiment, the circuit structure of the three-phase LLC power conversion circuit 1b is similar to that of the three-phase LLC power conversion circuit 1 shown in Figure 2, so its circuit structure will not be described again. However, in this embodiment, the first synchronous rectifier switch group of the output switch group 3 of the three-phase LLC power conversion circuit 1b is changed to a half-bridge structure, which includes a first upper rectifier switch SR1a and a first lower rectifier switch SR2a connected in series; the second synchronous rectifier switch group of the output switch group 3 is changed to a half-bridge structure, which includes a second upper rectifier switch SR3a and a second lower rectifier switch SR4a connected in series; and the third synchronous rectifier switch group of the output switch group 3 is changed to a half-bridge structure, which includes a third upper rectifier switch SR5a and a third lower rectifier switch SR6a connected in series.

[0063] Please refer to Figures 9, 10, and 11. Figure 9 is the circuit topology diagram of the fourth embodiment of the three-phase LLC power conversion circuit of this invention. Figures 10 and 11 are partial waveform timing diagrams of the operation of the three-phase LLC power conversion circuit when the control unit of the three-phase LLC power conversion circuit shown in Figure 9 is controlled under different implementation states. In this embodiment, the circuit structure of the three-phase LLC power conversion circuit 1c is similar to that of the three-phase LLC power conversion circuit 1b shown in Figure 8, so its circuit structure will not be described again. However, in this embodiment, the plurality of primary windings T1p, T2p, and T3p of the three-phase transformer T of the three-phase LLC power conversion circuit 1c are delta-connected (i.e., Δ-connected), and the plurality of secondary windings T1s, T2s, and T3s are delta-connected (i.e., Δ-connected).

[0064] As shown in Figure 10, the control unit 4 controls the switching state of at least one rectifier switch in the synchronous rectifier switch group of each phase's output switch group 3 to lead the switching state of the corresponding input switch in the input switch bridge arm of the same phase based on the ratio of the output voltage Vo to the input voltage Vin. (That is, the switching states of the first upper rectifier switch SR1a, the second upper rectifier switch SR3a, and the third upper rectifier switch SR5a lead the switching states of the first upper input switch Q1, the second upper input switch Q3, and the third upper input switch Q5, respectively). As shown in Figure 11, the control unit 4 can also be modified to control at least one rectifier switch in the synchronous rectifier switch group of each phase's output switch group 3 to perform synchronous rectification switching based on the ratio of the output voltage Vo to the input voltage Vin, and control the switching state of the remaining at least one rectifier switch in the synchronous rectifier switch group of each phase's output switch group 3 to lag the switching state of the corresponding input switch in the input switch bridge arm of the same phase (the switching state of the first upper rectifier switch SR1a lags the switching state of the first upper input switch Q1).

[0065] Please refer to Figures 12 and 13, where Figure 12 is the circuit topology diagram of the fifth embodiment of the three-phase LLC power conversion circuit of this invention, and Figure 13 is a waveform timing diagram of the control unit of the three-phase LLC power conversion circuit shown in Figure 12 during operation. In this embodiment, the three-phase LLC power conversion circuit 1d shows the detailed circuit architecture of the three-phase LLC power conversion circuit 1b shown in Figure 8. That is, the plurality of first resonant elements RE A1, RE B1, RE C1 of the three-phase LLC power conversion circuit 1c shown in Figure 8 are star-connected (i.e., Y-connected) and can be composed of capacitors Cr1, Cr2, and Cr3, respectively, as shown in Figure 12. The second resonant elements RE A2, RE B2, RE C2 are delta-connected (i.e., Δ-connected) and are composed of resonant inductors Lr1, Lr2, and Lr3, respectively. Ic1, Ic2, and Ic3 are the currents flowing through capacitors Cr1, Cr2, and Cr3, respectively; IL1, IL2, and IL3 are the currents flowing through resonant inductors Lr1, Lr2, and Lr3, respectively; and Is1, Is2, and Is3 are the currents flowing through the secondary windings of the first transformer T1, the second transformer T2, and the third transformer T3, respectively.

[0066] Figure 14 is a circuit topology diagram of the sixth embodiment of the three-phase LLC power conversion circuit of this case. In this embodiment, the circuit structure of the three-phase LLC power conversion circuit 1e is similar to that of the three-phase LLC power conversion circuit 1b shown in Figure 8, so its circuit structure will not be described again. However, in this 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 Q5, and the third lower input switch Q6 in the input switch group 2 of the three-phase LLC power conversion circuit 1e are electrically connected in a cascaded manner.

[0067] As can be seen from the above, the input switch group 2 of the three-phase LLC power conversion circuit can be one of the circuit structures of the input switch group 2 of the three-phase LLC power conversion circuit 1 shown in Figure 2 and the input switch group 2 of the three-phase LLC power conversion circuit 1a shown in Figure 7. Similarly, the output switch group 3 of the three-phase LLC power conversion circuit can be one of the circuit structures of the output switch group 3 of the three-phase LLC power conversion circuit 1 shown in Figure 2 and the output switch group 3 of the three-phase LLC power conversion circuit 1b shown in Figure 8. Furthermore, the plurality of first resonant elements RE A1, RE B1, and RE C1 can be star-connected (i.e., Y-connected) or delta-connected (i.e., Δ-connected), and can be composed of capacitors or resonant inductors respectively. The second resonant elements RE A2, RE B2, and RE C2 can be star-connected (i.e., Y-connected) or delta-connected (i.e., Δ-connected), and can be composed of capacitors or resonant inductors respectively. It should be emphasized that the circuit structure of the input switch group 2, the circuit structure of the output switch group 3, and the circuit structure of the resonant circuit group are not limited to the aforementioned embodiments, and can be adjusted according to actual application requirements.

[0068] To improve the flux cancellation between the three-phase transformer (e.g., the three-phase transformer T shown in Figure 2) and the three-phase resonant inductor (e.g., the second resonant element RE A2, RE B2, RE C2 shown in Figure 2) in the three-phase LLC power conversion circuit of the aforementioned embodiments, thereby improving core loss and reducing volume, this invention further matches the positions of the three-phase transformer and the resonant inductor in the resonant element to achieve flux cancellation, thus achieving the aforementioned objective. The following will illustrate different embodiments of position matching between the three-phase transformer and the resonant inductor in the resonant element. In the subsequent specification, the reference numerals A, B, and C respectively represent the first phase A, the second phase B, and the third phase C in the three phases. The first phase A leads the second phase B by 120 degrees, the second phase B leads the third phase C by 120 degrees, and the third phase C leads the first phase A by 120 degrees.

[0069] Please refer to Figures 15A, 15B, and 15C. Figure 15A is a circuit topology diagram of the first embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit in this invention. Figure 15B is a schematic diagram of the placement of the three-phase transformer and three-phase resonant inductor in the magnetic component shown in Figure 15A. Figure 15C is a schematic diagram of a portion of the magnetic flux vector of the magnetic component shown in Figure 15B. The magnetic component 5 in this embodiment includes a three-phase transformer, a three-phase resonant inductor, and a magnetic core assembly. The magnetic core assembly includes a single magnetic core 6. The three-phase transformer includes a first transformer TA, a second transformer TB, and a third transformer TC. The primary windings of the first transformer TA, the second transformer TB, and the third transformer TC are star-connected (Y-connected). The three-phase resonant inductor includes a first resonant inductor LrBC (BC-phase inductor), a second resonant inductor LrCA (CA-phase inductor), and a third resonant inductor LrAB (AB-phase inductor), which are electrically connected to the primary windings of the corresponding transformers in the first transformer TA, the second transformer TB, and the third transformer TC, respectively. The first resonant inductor LrBC, the second resonant inductor LrCA, and the third resonant inductor LrAB are connected in a delta configuration (Δ connection). In some embodiments, the three-phase transformer further includes a first magnetizing inductor LmA, a second magnetizing inductor LmB, and a third magnetizing inductor LmC, which are connected in parallel to the primary windings of the corresponding transformers in the first transformer TA, the second transformer TB, and the third transformer TC, respectively.

[0070] In the magnetic assembly 5, the first resonant inductor LrBC, the second resonant inductor LrCA, and the third resonant inductor LrAB are horizontally adjacent to each other on the first side of the magnetic core 6, and the first transformer TA, the second transformer TB, and the third transformer TC are horizontally adjacent to each other on the second side of the magnetic core 6, with the first side and the second side opposite to each other. Furthermore, when the ratio of the inductance value of the resonant inductor to the inductance value of the corresponding excitation inductor is greater than a set value, for example, 10, the resonant inductors and transformers located in different phases are arranged adjacent to each other; that is, the first transformer TA and the first resonant inductor LrBC are horizontally adjacent, the second transformer TB and the second resonant inductor LrCA are horizontally adjacent, and the third transformer TC and the third resonant inductor LrAB are horizontally adjacent. Additionally, the phase angle between the magnetic flux direction of the adjacent resonant inductors and the magnetic flux direction of the transformers is greater than 90 degrees and less than 270 degrees. Since the adjacent resonant inductors and transformers are horizontally arranged, the winding direction of the adjacent resonant inductors is opposite to the winding direction of the transformers.

[0071] Figure 15C shows the magnetic fluxes ΦLrBC, ΦLrCA, and ΦLrAB of the first resonant inductor LrBC, the second resonant inductor LrCA, and the third resonant inductor LrAB, respectively. It also shows the magnetic fluxes ΦmA, ΦmB, and ΦmC of the first transformer TA, the second transformer TB, and the third transformer TC, respectively. Furthermore, it shows the magnetic fluxes ΦLrA, ΦLrB, and ΦLrC of the resonant inductors in phases A, B, and C. By configuring the first transformer TA, the second transformer TB, and the third transformer TC with the first resonant inductors LrBC, the second resonant inductors LrCA, and the third resonant inductors LrAB, the magnetic fluxes of the resonant inductors and transformers in different phases can be canceled out. For example, the magnetic flux of the first transformer TA partially cancels out the magnetic flux of the first resonant inductor LrBC, thus forming the total magnetic flux ΦΣA in phase A. This improves the loss of the magnetic core 6 and reduces its volume.

[0072] Please refer to Figures 16A and 16B, where Figure 16A is a schematic diagram of another variation of the arrangement of the three-phase transformer and three-phase resonant inductor in the magnetic component shown in Figure 15A, and Figure 16B is a schematic diagram of a portion of the magnetic flux vector of the magnetic component shown in Figure 16A. In some embodiments, when the ratio of the inductance value of the resonant inductor to the inductance value of the corresponding excitation inductor is less than a set value, the resonant inductors and transformers located in the same phase are arranged adjacent to each other, that is, the first transformer TA and the second resonant inductor LrCA are arranged horizontally adjacent, the second transformer TB and the third resonant inductor LrAB are arranged horizontally adjacent, and the third transformer TC and the first resonant inductor LrBC are arranged horizontally adjacent. In addition, the phase angle between the magnetic flux direction of the adjacent resonant inductors and the magnetic flux direction of the transformer is greater than 90 degrees and less than 270 degrees. Furthermore, since the adjacent resonant inductors and transformers are arranged horizontally, the winding direction of the adjacent resonant inductors is opposite to the winding direction of the transformers.

[0073] Please refer to Figures 17A, 17B, 17C, and 17D. Figure 17A is a circuit topology diagram of a second embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit, Figure 17B is a circuit topology diagram of a third embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit, Figure 17C is a schematic diagram of the placement of the three-phase transformer and three-phase resonant inductor in the magnetic component shown in Figures 17A or 17B, and Figure 17D is a schematic diagram of a portion of the magnetic flux vector of the magnetic component shown in Figure 17C. In the magnetic component 5a shown in Figure 17A, the primary windings of the first transformer TA, the second transformer TB, and the third transformer TC of the three-phase transformer are connected in a star configuration (Y-connection). The first resonant inductor LrA, the second resonant inductor LrB, and the third resonant inductor LrC of the three-phase resonant inductors are electrically connected to the primary windings of the corresponding transformers in the first transformer TA, the second transformer TB, and the third transformer TC, respectively, and the first resonant inductor LrA, the second resonant inductor LrB, and the third resonant inductor LrC are connected in a star configuration (Y connection).

[0074] In the magnetic component 5b shown in Figure 17B, the first transformer TA, the second transformer TB, and the third transformer TC of the three-phase transformers are independent and each is 120 degrees out of phase. The first resonant inductor LrA, the second resonant inductor LrB, and the third resonant inductor LrC of the three-phase resonant inductors are also independent and each is 120 degrees out of phase. The first resonant inductor LrA, the second resonant inductor LrB, and the third resonant inductor LrC are electrically connected to the primary windings of the corresponding transformers in the first transformer TA, the second transformer TB, and the third transformer TC, respectively.

[0075] In magnetic components 5a or 5b, the first resonant inductor LrA, the second resonant inductor LrB, and the third resonant inductor LrC are horizontally adjacent to each other on the first side of the magnetic core 6, and the first transformer TA, the second transformer TB, and the third transformer TC are horizontally adjacent to each other on the second side of the magnetic core 6, with the first side and the second side opposite to each other. Furthermore, resonant inductors and transformers located in different phases are arranged adjacent to each other; that is, the first transformer TA and the third resonant inductor LrC are horizontally adjacent, the second transformer TB and the first resonant inductor LrA are horizontally adjacent, and the third transformer TC and the second resonant inductor LrB are horizontally adjacent. Moreover, the phase angle between the magnetic flux direction of the adjacent resonant inductors and the magnetic flux direction of the transformers is greater than 90 degrees and less than 270 degrees. Additionally, because the adjacent resonant inductors and transformers are horizontally arranged, the winding direction of the adjacent resonant inductors is opposite to the winding direction of the transformers.

[0076] Figure 17D shows the magnetic fluxes ΦLrA, ΦLrB, and ΦLrC of the first resonant inductor LrA, the second resonant inductor LrB, and the third resonant inductor LrC, respectively. It also shows the magnetic fluxes ΦmA, ΦmB, and ΦmC of the first transformer TA, the second transformer TB, and the third transformer TC. By configuring the first transformer TA, the second transformer TB, and the third transformer TC with the first resonant inductor LrA, the second resonant inductor LrB, and the third resonant inductor LrC, magnetic flux cancellation can be achieved between the resonant inductors and transformers of different phases. For example, the magnetic flux of the first transformer TA partially cancels out the magnetic flux of the third resonant inductor LrC, thus forming the total magnetic flux ΦΣA of phase A. This improves the loss of the magnetic core 6 and reduces its volume.

[0077] Please refer to Figures 18A and 18B, where Figure 18A is a schematic diagram of another variation of the arrangement of the three-phase transformer and three-phase resonant inductor in the magnetic assembly shown in Figures 17A or 17B, and Figure 18B is a schematic diagram of a portion of the magnetic flux vector of the magnetic assembly shown in Figure 18A. In some embodiments, the resonant inductors and transformers located in phase are arranged adjacent to each other, that is, the first transformer TA and the first resonant inductor LrA are arranged horizontally adjacent, the second transformer TB and the second resonant inductor LrB are arranged adjacent, and the third transformer TC and the third resonant inductor LrC are arranged horizontally adjacent. Furthermore, the phase angle between the magnetic flux direction of the adjacent resonant inductors and the magnetic flux direction of the transformer is greater than 90 degrees and less than 270 degrees. In addition, since the adjacent resonant inductors and transformers are arranged horizontally, the winding direction of the adjacent resonant inductors is opposite to the winding direction of the transformers.

[0078] Please refer to Figures 19A, 19B, and 19C. Figure 19A is a circuit topology diagram of the fourth embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit in this invention. Figure 19B is a schematic diagram of the placement of the three-phase transformer and three-phase resonant inductor in the magnetic component shown in Figure 19A. Figure 19C is a schematic diagram of a portion of the magnetic flux vector of the magnetic component shown in Figure 19B. The magnetic component 5c in this embodiment includes a three-phase transformer, a three-phase resonant inductor, and a magnetic core 6. The three-phase transformer includes a first transformer TAB, a second transformer TBC, and a third transformer TCA. The primary windings of the first transformer TAB, the second transformer TBC, and the third transformer TCA are delta-connected (Δ-connected). The three-phase resonant inductor includes a first resonant inductor LrA, a second resonant inductor LrB, and a third resonant inductor LrC, which are electrically connected to the primary windings of two corresponding transformers in the first transformer TAB, the second transformer TBC, and the third transformer TCA, respectively. The first resonant inductor LrA, the second resonant inductor LrB, and the third resonant inductor LrC are connected in a star (Y) configuration. In some embodiments, the three-phase transformer further includes a first magnetizing inductor LmAB, a second magnetizing inductor LmBC, and a third magnetizing inductor LmCA, which are connected in parallel to the primary windings of the corresponding transformers in the first transformer TAB, the second transformer TBC, and the third transformer TCA, respectively.

[0079] In the magnetic assembly 5c, the first resonant inductor LrA, the second resonant inductor LrB, and the third resonant inductor LrC are horizontally adjacent to each other on the first side of the magnetic core 6, and the first transformer TAB, the second transformer TBC, and the third transformer TCA are horizontally adjacent to each other on the second side of the magnetic core 6, with the first side and the second side opposite to each other. Furthermore, resonant inductors and transformers located in different phases are arranged adjacent to each other; that is, the first transformer TAB and the third resonant inductor LrC are horizontally adjacent, the second transformer TBC and the first resonant inductor LrA are horizontally adjacent, and the third transformer TCA and the second resonant inductor LrB are horizontally adjacent. Moreover, the phase angle between the magnetic flux direction of the adjacent resonant inductors and the magnetic flux direction of the transformers is greater than 90 degrees and less than 270 degrees. Additionally, because the adjacent resonant inductors and transformers are horizontally arranged, the winding direction of the adjacent resonant inductors is opposite to the winding direction of the transformers.

[0080] Figure 19C shows the magnetic fluxes ΦLrA, ΦLrB, and ΦLrC of the first resonant inductor LrA, the second resonant inductor LrB, and the third resonant inductor LrC, respectively. It also shows the magnetic fluxes ΦmAB, ΦmBC, and ΦmCA of the first transformer TAB, the second transformer TBC, and the third transformer TCA, respectively. Furthermore, it shows the magnetic fluxes ΦLrAB, ΦLrBC, and ΦLrCA of the resonant inductors in phases AB, BC, and CA. By configuring the first transformer TAB, the second transformer TBC, and the third transformer TCA with the first resonant inductor LrA, the second resonant inductor LrB, and the third resonant inductor LrC, the magnetic fluxes of the resonant inductors and transformers in different phases can be canceled out. For example, the magnetic flux of the first transformer TAB partially cancels out the magnetic flux of the third resonant inductor LrC, thereby improving the loss of the magnetic core 6 and reducing its volume.

[0081] Please refer to Figures 20A and 20B, where Figure 20A is a schematic diagram of another variation of the arrangement of the three-phase transformer and three-phase resonant inductor in the magnetic assembly shown in Figure 19A, and Figure 20B is a schematic diagram of a portion of the magnetic flux vector of the magnetic assembly shown in Figure 20A. In some embodiments, the resonant inductors and transformers located in phase are arranged adjacent to each other, that is, the first transformer TAB and the first resonant inductor LrA are horizontally adjacent, the second transformer TBC and the second resonant inductor LrB are horizontally adjacent, and the third transformer TCA and the third resonant inductor LrC are horizontally adjacent. Furthermore, the phase angle between the magnetic flux direction of the adjacent resonant inductors and the magnetic flux direction of the transformers is greater than 90 degrees and less than 270 degrees. In addition, since the adjacent resonant inductors and transformers are arranged horizontally, the winding direction of the adjacent resonant inductors is opposite to the winding direction of the transformers.

[0082] Please refer to Figures 21A, 21B, and 21C. Figure 21A is a circuit topology diagram of the fifth embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit in this invention. Figure 21B is a schematic diagram of the placement of the three-phase transformer and three-phase resonant inductor in the magnetic component shown in Figure 21A. Figure 21C is a schematic diagram of a portion of the magnetic flux vector of the magnetic component shown in Figure 21B. The magnetic component 5d in this embodiment includes a three-phase transformer, a three-phase resonant inductor, and a magnetic core 6. The three-phase transformer includes a first transformer TAB, a second transformer TBC, and a third transformer TCA. The primary windings of the first transformer TAB, the second transformer TBC, and the third transformer TCA are delta-connected (Δ-connected). The three-phase resonant inductor includes a first resonant inductor LrBC, a second resonant inductor LrCA, and a third resonant inductor LrAB. The third resonant inductor LrAB, the first resonant inductor LrBC, and the second resonant inductor LrCA are electrically connected to the primary windings of two corresponding transformers among the first transformer TAB, the second transformer TBC, and the third transformer TCA, respectively. The first resonant inductor LrBC, the second resonant inductor LrCA, and the third resonant inductor LrAB are connected in a delta configuration (Δ connection). In some embodiments, the three-phase transformer further includes a first magnetizing inductor LmAB, a second magnetizing inductor LmBC, and a third magnetizing inductor LmCA, which are connected in parallel to the primary windings of the corresponding transformers among the first transformer TAB, the second transformer TBC, and the third transformer TCA, respectively.

[0083] In the magnetic assembly 5d, the third resonant inductor LrAB, the first resonant inductor LrBC, and the second resonant inductor LrCA are horizontally adjacent to each other on the first side of the magnetic core 6, and the first transformer TAB, the second transformer TBC, and the third transformer TCA are horizontally adjacent to each other on the second side of the magnetic core 6, with the first side and the second side opposite to each other. Furthermore, resonant inductors and transformers located in different phases are arranged adjacent to each other; that is, the first transformer TAB and the second resonant inductor LrCA are horizontally adjacent, the second transformer TBC and the third resonant inductor LrAB are horizontally adjacent, and the third transformer TCA and the first resonant inductor LrBC are horizontally adjacent. Moreover, the phase angle between the magnetic flux direction of the adjacent resonant inductors and the magnetic flux direction of the transformers is greater than 90 degrees and less than 270 degrees. Additionally, because the adjacent resonant inductors and transformers are horizontally arranged, the winding direction of the adjacent resonant inductors is opposite to the winding direction of the transformers.

[0084] Figure 21C shows the magnetic fluxes ΦLrAB, ΦLrBC, and ΦLrCA of the third resonant inductor LrAB, the first resonant inductor LrBC, and the second resonant inductor LrCA, respectively. It also shows the magnetic fluxes ΦmAB, ΦmBC, and ΦmCA of the first transformer TAB, the second transformer TBC, and the third transformer TCA, respectively. By configuring the first transformer TAB, the second transformer TBC, and the third transformer TCA with the third resonant inductor LrAB, the first resonant inductor LrBC, and the second resonant inductor LrCA, magnetic flux cancellation can be achieved between the resonant inductors and transformers of different phases. For example, the magnetic flux of the first transformer TAB partially cancels out the magnetic flux of the second resonant inductor LrCA, thereby improving the loss of the magnetic core 6 and reducing its volume.

[0085] Please refer to Figures 22A and 22B, where Figure 22A is a schematic diagram of another variation of the arrangement of the three-phase transformer and three-phase resonant inductor in the magnetic component shown in Figure 21A, and Figure 22B is a schematic diagram of part of the magnetic flux vector of the magnetic component shown in Figure 22A. In some embodiments, the resonant inductors and transformers located in phase are arranged adjacent to each other, that is, the first transformer TAB and the third resonant inductor LrAB are horizontally adjacent, the second transformer TBC and the first resonant inductor LrBC are horizontally adjacent, and the third transformer TCA and the second resonant inductor LrCA are horizontally adjacent. In addition, the phase angle between the magnetic flux direction of the adjacent resonant inductors and the magnetic flux direction of the transformers is greater than 90 degrees and less than 270 degrees. Furthermore, since the adjacent resonant inductors and transformers are arranged horizontally, the winding direction of the adjacent resonant inductors is opposite to the winding direction of the transformers.

[0086] Please refer to Figures 23A, 23B, 23C, 23D, 23E, and 23F. Figure 23A is a circuit topology diagram of the sixth embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit, Figure 23B is a circuit topology diagram of the seventh embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit, Figure 23C is a circuit topology diagram of the eighth embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit, Figure 23D is a circuit topology diagram of the ninth embodiment of the magnetic component applicable to a three-phase LLC power conversion circuit, Figure 23E is a schematic diagram of the placement of the three-phase transformer and three-phase resonant inductor of the magnetic component shown in Figures 23A, 23B, 23C, or 23D, and Figure 23F is a schematic diagram of a portion of the magnetic flux vector of the magnetic component shown in Figure 23E. The magnetic component 5e shown in Figure 23A includes a three-phase transformer, a first set of three-phase resonant inductors, a second set of three-phase resonant inductors, and a magnetic core 6. The primary windings of the first transformer TA, the second transformer TB, and the third transformer TC of the three-phase transformer are connected in a star (Y-connection), and the secondary windings of the first transformer TA, the second transformer TB, and the third transformer TC are also connected in a star (Y-connection). The first set of three-phase resonant inductors includes a first resonant inductor LrA1, a second resonant inductor LrB1, and a third resonant inductor LrC1. The first resonant inductor LrA1, the second resonant inductor LrB1, and the third resonant inductor LrC1 are electrically connected to the primary windings of the corresponding transformers in the first transformer TA, the second transformer TB, and the third transformer TC, and the first resonant inductor LrA1, the second resonant inductor LrB1, and the third resonant inductor LrC1 are connected in a star (Y-connection). The second group of three-phase resonant inductors includes the fourth resonant inductor LrA2, the fifth resonant inductor LrB2, and the sixth resonant inductor LrC2. The fourth resonant inductor LrA2, the fifth resonant inductor LrB2, and the sixth resonant inductor LrC2 are electrically connected to the secondary windings of the corresponding transformers in the first transformer TA, the second transformer TB, and the third transformer TC, respectively. The fourth resonant inductor LrA2, the fifth resonant inductor LrB2, and the sixth resonant inductor LrC2 are connected in a star configuration (Y connection).

[0087] In the magnetic assembly 5f shown in Figure 23B, the first transformer TA, the second transformer TB, and the third transformer TC of the three-phase transformers are independent and each is 120 degrees out of phase. The first resonant inductor LrA1, the second resonant inductor LrB1, and the third resonant inductor LrC1 of the first group of three-phase resonant inductors are also independent and each is 120 degrees out of phase. Furthermore, the first resonant inductor LrA1, the second resonant inductor LrB1, and the third resonant inductor LrC1 are electrically connected to the primary windings of the corresponding transformers in the first transformer TA, the second transformer TB, and the third transformer TC, respectively. The fourth resonant inductor LrA2, the fifth resonant inductor LrB2, and the sixth resonant inductor LrC2 of the second group of three-phase resonant inductors are also independent and each is 120 degrees out of phase. Furthermore, the fourth resonant inductor LrA2, the fifth resonant inductor LrB2, and the sixth resonant inductor LrC2 are electrically connected to the secondary windings of the corresponding transformers in the first transformer TA, the second transformer TB, and the third transformer TC, respectively.

[0088] In the magnetic component 5g shown in Figure 23C, the magnetic component 5g includes a three-phase transformer, a first set of three-phase resonant inductors, a second set of three-phase resonant inductors, and a magnetic core 6. The primary windings of the first transformer TA, the second transformer TB, and the third transformer TC of the three-phase transformer are connected in a star configuration (Y-connection). The first set of three-phase resonant inductors includes a first resonant inductor LrA1, a second resonant inductor LrB1, and a third resonant inductor LrC1. The first resonant inductor LrA1, the second resonant inductor LrB1, and the third resonant inductor LrC1 are electrically connected to the primary windings of the corresponding transformers in the first transformer TA, the second transformer TB, and the third transformer TC, and the first resonant inductor LrA1, the second resonant inductor LrB1, and the third resonant inductor LrC1 are connected in a star configuration (Y-connection). The second group of three-phase resonant inductors includes a fourth resonant inductor LrA2, a fifth resonant inductor LrB2, and a sixth resonant inductor LrC2. The fourth resonant inductor LrA2, the fifth resonant inductor LrB2, and the sixth resonant inductor LrC2 are respectively electrically connected between the corresponding resonant inductors of the first resonant inductor LrA1, the second resonant inductor LrB1, and the third resonant inductor LrC1 and the primary windings of the corresponding transformers of the first transformer TA, the second transformer TB, and the third transformer TC. The fourth resonant inductor LrA2, the fifth resonant inductor LrB2, and the sixth resonant inductor LrC2 are connected in a star configuration (Y connection).

[0089] In the magnetic assembly 5h shown in Figure 23D, the first transformer TA, the second transformer TB, and the third transformer TC of the three-phase transformers are independent and are 120 degrees apart. The first resonant inductor LrA1, the second resonant inductor LrB1, and the third resonant inductor LrC1 of the first group of three-phase resonant inductors are also independent and are 120 degrees apart. The first resonant inductor LrA1, the second resonant inductor LrB1, and the third resonant inductor LrC1 are electrically connected to the primary windings of the corresponding transformers in the first transformer TA, the second transformer TB, and the third transformer TC. The fourth resonant inductor LrA2, the fifth resonant inductor LrB2, and the sixth resonant inductor LrC2 of the second group of three-phase resonant inductors are independent and 120 degrees apart. The fourth resonant inductor LrA2, the fifth resonant inductor LrB2, and the sixth resonant inductor LrC2 are electrically connected to the primary windings of the corresponding resonant inductors of the first resonant inductor LrA1, the second resonant inductor LrB1, and the third resonant inductor LrC1, respectively, and the primary windings of the corresponding transformers of the first transformer TA, the second transformer TB, and the third transformer TC.

[0090] In magnetic components 5e, 5f, 5g, or 5h, the first resonant inductor LrA1, the second resonant inductor LrB2, and the third resonant inductor LrC2 are horizontally adjacent to each other on the first side of the magnetic core 6; the fourth resonant inductor LrA2, the fifth resonant inductor LrB2, and the sixth resonant inductor LrC2 are horizontally adjacent to each other on the second side of the magnetic core 6; and the first transformer TA, the second transformer TB, and the third transformer TC are horizontally positioned between the first and second sides of the magnetic core 6, between the first group of three-phase resonant inductors and the second group of three-phase resonant inductors, with the first side opposite to the second side. Furthermore, resonant inductors and transformers located in different phases are arranged adjacent to each other; that is, the first transformer TA is horizontally adjacent to the third resonant inductor LrC1 and the sixth resonant inductor LrC2, the second transformer TB is horizontally adjacent to the first resonant inductor LrA1 and the fourth resonant inductor LrA2, and the third transformer TC is horizontally adjacent to the second resonant inductor LrB1 and the fifth resonant inductor LrB2. Furthermore, 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. Additionally, because the adjacent resonant inductor and transformer are horizontally positioned, the winding direction of the adjacent resonant inductor is opposite to that of the transformer.

[0091] Figure 23F shows the magnetic fluxes ΦLrA1, ΦLrB1, ΦLrC1, ΦLrA2, ΦLrB2, and ΦLrC2 of the first resonant inductor LrA1, the second resonant inductor LrB1, the third resonant inductor LrC1, the fourth resonant inductor LrA2, the fifth resonant inductor LrB2, and the sixth resonant inductor LrC2. It also shows the magnetic fluxes ΦmA, ΦmB, and ΦmC of the first transformer TA, the second transformer TB, and the third transformer TC. By configuring the first transformer TA, the second transformer TB, and the third transformer TC with the first resonant inductor LrA1, the second resonant inductor LrB1, the third resonant inductor LrC1, the fourth resonant inductor LrA2, the fifth resonant inductor LrB2, and the sixth resonant inductor LrC2, the magnetic flux of the resonant inductors of different phases can be canceled out. For example, the magnetic flux of the first transformer TA partially cancels out the magnetic flux of the third resonant inductor LrC1 and the sixth resonant inductor LrC2 to form the total magnetic flux ΦΣA of phase A; the magnetic flux of the second transformer TB partially cancels out the magnetic flux of the first resonant inductor LrA1 and the fourth resonant inductor LrA2 to form the total magnetic flux ΦΣB of phase B; and the magnetic flux of the third transformer TC partially cancels out the magnetic flux of the second resonant inductor LrB1 and the fifth resonant inductor LrB2 to form the total magnetic flux ΦΣC of phase C. This improves the loss of the magnetic core 6 and reduces its volume.

[0092] In the aforementioned embodiments, the three-phase transformer and three-phase resonant inductor of the magnetic component can also be stacked and vertically arranged on the core assembly, with the winding direction of adjacent resonant inductors being the same as the winding direction of the transformer. Several possible embodiments will be listed below for illustrative purposes. Please refer to Figure 24, which is a schematic diagram of another variation in the arrangement position of the three-phase transformer and three-phase resonant inductor of the magnetic component in the embodiment shown in Figure 15A. As shown in Figure 24, the circuit architecture of the magnetic component in this embodiment is similar to that of the magnetic component 5 shown in Figure 15A. In this embodiment, the core assembly of the magnetic component includes a first core 6a and a second core 6b, with the first core 6a vertically arranged above the second core 6b. The first resonant inductor LrBC, the second resonant inductor LrCA, and the third resonant inductor LrAB are arranged on the first core 6a. The first transformer TA, the second transformer TB, and the third transformer TC are arranged on the second core 6b. Furthermore, resonant inductors and transformers located in different phases are arranged adjacent to each other. Specifically, the first transformer TA is perpendicularly adjacent to the first resonant inductor LrBC, the second transformer TB is perpendicularly adjacent to the second resonant inductor LrCA, and the third transformer TC is perpendicularly adjacent to the third resonant inductor LrAB. The phase angle between the magnetic flux direction of the perpendicularly adjacent resonant inductors and the magnetic flux direction of the transformers is between -90 degrees and +90 degrees. The positive direction of the magnetic flux is from bottom to top, and the winding direction of the adjacent resonant inductors is the same as the winding direction of the transformers.

[0093] Figure 25 is a schematic diagram showing another variation of the placement of the three-phase transformer and three-phase resonant inductor in the magnetic component shown in Figure 23E. As shown in Figure 25, the circuit architecture of the magnetic component in this embodiment is similar to that of magnetic components 5e, 5f, 5g, or 5h shown in Figures 23A, 23B, 23C, or 23D. In this embodiment, the magnetic core assembly includes a first magnetic core 6a, a second magnetic core 6b, and a third magnetic core 6c. The first magnetic core 6a is vertically positioned above the second magnetic core 6b, and the second magnetic core 6b is vertically positioned above the third magnetic core 6c. The first resonant inductor LrA1, the second resonant inductor LrB1, and the third resonant inductor LrC1 are disposed on the first magnetic core 6a. The first transformer TA, the second transformer TB, and the third transformer TC are disposed on the second magnetic core 6b, and the fourth resonant inductor LrA2, the fifth resonant inductor LrB2, and the sixth resonant inductor LrC2 are disposed on the third magnetic core 6c. Furthermore, resonant inductors and transformers located in different phases are arranged adjacent to each other. Specifically, the first transformer TA is perpendicularly adjacent to the third resonant inductor LrC1 and the sixth resonant inductor LrC2; the second transformer TB is perpendicularly adjacent to the first resonant inductor LrA1 and the fourth resonant inductor LrA2; and the third transformer TC is perpendicularly adjacent to the second resonant inductor LrB1 and the fifth resonant inductor LrB2. The phase angle between the magnetic flux direction of the perpendicularly adjacent resonant inductors and the magnetic flux direction of the transformer is between -90 degrees and +90 degrees, wherein the positive magnetic flux direction is from bottom to top, and the winding direction of the adjacent resonant inductors is the same as the winding direction of the transformers.

[0094] In summary, this invention provides a magnetic component suitable for three-phase power conversion circuits. The three transformers in the magnetic component are connected in a star, delta, or independent configuration, each 120 degrees phase apart. Similarly, the three resonant inductors in the magnetic component are also connected in a star, delta, or independent configuration, each 120 degrees phase apart. The resonant inductors in the same or different phases are arranged adjacent to the transformers. For horizontally adjacent resonant inductors, the phase angle between their magnetic flux direction and the transformer's magnetic flux direction is greater than 90 degrees and less than 270 degrees. For vertically adjacent resonant inductors, the phase angle between their magnetic flux direction and the transformer's magnetic flux direction is between -90 degrees and +90 degrees, with the positive magnetic flux direction being from bottom to top. Therefore, the adjacent resonant inductors and transformers can achieve magnetic flux cancellation, thereby improving core losses and reducing core volume.

[0095] 1, 1a, 1b, 1c, 1d, 1e: Three-phase LLC power conversion circuit DC: Input power V in: Input voltage R: Load V o: Output voltage V ref: Reference voltage T: Three-phase transformer 2: Input switch group 3: Output switch group 4: Control Unit Q1: First upper input switch Q2: First input switch Q3: Second upper input switch Q4: Second input switch Q5: Third upper input switch Q6: Third input switch T1, TA, TAB: First transformer T2, TB, TBC: Second transformer T3, TC, TCA: Third transformer Lm1, Lm2, Lm3: Magnetizing inductors RE A1, RE B1, RE C1: First resonant element RE A2, RE B2, RE C2: Second resonant elements SR1, SR1a: First upper rectifier switch SR2, SR2a: First lower rectifier switch SR3, SR3a: Second upper rectifier switch SR4, SR4a: Second lower rectifier switch SR5, SR5a: Third upper rectifier switch SR6, SR6a: Third lower rectifier switch SR7: Fourth upper rectifier switch SR8: Fourth lower rectifier switch SR9: Fifth upper rectifier switch SR10: Fifth lower rectifier switch SR11: Sixth upper rectifier switch SR12: Sixth lower rectifier switch △T 1: First time △T 2: Second time I p1, I M1, I s1, I s2, I s3, I C1, I C2, I C3, I L1, I L2, I L3: current 41: Zero Current Detection Circuit 42: Gain Control Circuit 43: First Driver 44: Subtractor 45: Compensation Circuit 46: Voltage-controlled oscillator 47: Second Driver S1~S2: Steps of the control method T1p, T2p, T3p: Primary winding T1s, T2s, T3s: Secondary windings Cr1, Cr2, Cr3: Capacitors Lr1, Lr2 and Lr3: Resonant inductors LrBC, LrA, LrA1: First resonant inductor LrCA, LrB, LrB1: Second resonant inductor LrAB, LrC, LrC1: Third resonant inductor 5, 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h: Magnetic components 6: Magnetic core 6a: First magnetic core 6b: Second magnetic core 6c: Third magnetic core L mA, L mAB: First magnetizing inductance LmB, LmBC: Second magnetizing inductance LmC, LmCA: Third magnetizing inductor Φ LrBC, Φ LrCA, Φ LrAB, Φ mA, Φ mB, Φ mC, Φ LrA, Φ LrB, Φ LrC, Φ ΣA, Φ ΣB, Φ ΣC, Φ mAB, Φ mBC, Φ mCA, Φ LrA1, Φ LrB1, Φ LrC1, Φ LrA2, Φ LrB2, Φ LrC2: magnetic flux L rA2: Fourth resonant inductor L rB2: Fifth resonant inductor LrC2: Sixth resonant inductor

Claims

1. A magnetic component suitable for a three-phase LLC power conversion circuit, comprising: a magnetic core assembly including at least one magnetic core; a three-phase transformer including three transformers respectively applied to a first phase, a second phase and a third phase of the three phases; and a first group of three-phase resonant inductors including three resonant inductors respectively applied to the first phase, the second phase and the third phase, wherein each of the resonant inductors is electrically connected to the primary winding of the corresponding at least one transformer; The three transformers and the three resonant inductors of the first group of three-phase resonant inductors are disposed on the magnetic core assembly. The primary windings of the three transformers are connected in a star, delta, or independent configuration, and are 120 degrees apart. The three resonant inductors of the first group of three-phase resonant inductors are connected in a star, delta, or independent configuration, and are 120 degrees apart. The resonant inductors in the same phase or different phases are disposed adjacent to the transformers. 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, or between -90 degrees and +90 degrees.

2. The magnetic assembly as claimed in claim 1, wherein the three transformers and the three resonant inductors are horizontally disposed on the magnetic core assembly, and the winding direction of the adjacent resonant inductors is opposite to the winding direction of the transformers.

3. The magnetic component as claimed in claim 2, wherein the phase angle between the magnetic flux direction of the horizontally adjacent resonant inductor and the magnetic flux direction of the corresponding transformer is greater than 90 degrees and less than 270 degrees.

4. The magnetic assembly as claimed in claim 1, wherein the three transformers and the three resonant inductors are stacked perpendicularly on the magnetic core assembly, and the winding direction of adjacent resonant inductors is the same as the winding direction of the transformers.

5. The magnetic assembly as claimed in claim 4, wherein the phase angle between the magnetic flux direction of the perpendicularly adjacent resonant inductor and the magnetic flux direction of the corresponding transformer is between -90 degrees and +90 degrees, wherein, The positive direction of the magnetic flux is from bottom to top.

6. The magnetic assembly as claimed in claim 1, wherein the three-phase transformer includes three magnetizing inductors, each connected in parallel with the primary winding of the corresponding transformer among the three transformers.

7. The magnetic component as claimed in claim 6, wherein the resonant inductor in phase is disposed adjacent to the transformer, and the ratio of the inductance value of the resonant inductor to the inductance value of the corresponding excitation inductor is less than a predetermined value.

8. The magnetic component as claimed in claim 6, wherein the resonant inductor in a different phase is disposed adjacent to the transformer, and the ratio of the inductance value of the resonant inductor to the inductance value of the corresponding magnetizing inductor is greater than a predetermined value.

9. The magnetic assembly as claimed in claim 1, wherein the primary winding system of the three transformers is star-connected and the three resonant inductors are delta-connected.

10. The magnetic assembly as claimed in claim 1, wherein the primary winding system of the three transformers is star-connected and the three resonant inductors are star-connected.

11. The magnetic assembly as claimed in claim 1, wherein the primary winding system of the three transformers is delta-connected and the three resonant inductors are star-connected.

12. The magnetic assembly as claimed in claim 1, wherein the primary windings of the three transformers are delta-connected and the three resonant inductors are delta-connected.

13. The magnetic assembly as claimed in claim 1, wherein the primary windings of the three transformers are independent and 120 degrees apart, and the three resonant inductors are independent and 120 degrees apart.

14. The magnetic assembly as claimed in claim 1, wherein the magnetic assembly includes a second set of three-phase resonant inductors, the second set of three-phase resonant inductors comprising three resonant inductors, each of the second set of three-phase resonant inductors being electrically connected to a corresponding secondary winding of at least one of the transformers.

15. The magnetic assembly as claimed in claim 14, wherein the three resonant inductors of the second group of three-phase resonant inductors are respectively electrically connected to the secondary winding of at least one of the corresponding transformers, and the three resonant inductors of the second group of three-phase resonant inductors are connected in a star, delta, or independently and are 120 degrees apart, and the resonant inductors of the second group of three-phase resonant inductors in the same phase or different phases are adjacent to the transformer, and the phase angle between the magnetic flux direction of the adjacent resonant inductors of the second group of three-phase resonant inductors and the magnetic flux direction of the transformer is greater than 90 degrees and less than 270 degrees or between -90 degrees and +90 degrees.

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