Patent Publication Number: US-2022230798-A1

Title: Power conversion module and magnetic device thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to China Patent Application No. 202110075991.X, filed on Jan. 20, 2021, the entire content of which is incorporated herein by reference for all purposes. 
     FIELD OF THE INVENTION 
     The present disclosure relates to a power electronic device, and more particularly to a power conversion module and a magnetic device thereof. 
     BACKGROUND OF THE INVENTION 
     Nowadays, power electronic devices are used as important parts of power conversion and widely used in power, electronics, electrical and energy industries. It is an important goal for those skilled in the art to ensure the long-term stable operations of the power electronic devices and improve the power conversion efficiency of the power electronic devices. 
     With the rapid development of mobile communication technologies and cloud computing technologies, high-power DC/DC power conversion modules have also been widely used in communication products. Due to the high power and miniaturization of the communication products, it is a challenge to increase the power conversion efficiency of the power conversion module and reduce the volume of the power conversion module. Therefore, how to design a reasonable structure and layout for the power conversion module, improve the power conversion efficiency of the power conversion module and reduce the volume of the power conversion module is one of the important issues in this technical field. 
     For reducing the volume of the output filter and expanding the system output power, the conventional power conversion module usually uses a parallel-connected circuit topology. That is, the conventional power conversion module includes two power conversion circuits connected in parallel. For example, the conventional power conversion module includes two buck-type power conversion circuits connected in parallel. In order to optimize the ripple characteristics of the output current of a plurality of parallel-connected circuits, a magnetic integration technology is used to make a plurality of inductors in the two power conversion circuits of the power conversion module to form a magnetic integration coupling relationship. That is, two inductors of the two power conversion circuits are formed as two coupled inductors. 
     In accordance with the magnetic integration technology, the magnetic device of the conventional power conversion module is usually equipped with an E-shaped core. The E-shaped core has two winding grooves. The two opposite ends of each winding groove are exposed to two opposite lateral sides of the E-shaped core. Since the installation positions of the two coupled inductors formed by two windings and the E-shaped core are different, the distances from the two coupled inductors to the output terminal of the power conversion module respectively are different. Under this circumstance, the equivalent series resistances of the two coupled inductors are not symmetric, and the currents flowing through the two coupled inductors are not uniformly distributed. Since the DC magnetic fluxes flowing through the lateral legs of the E-shaped core are larger, the lateral legs of the E-shaped core are readily subjected to magnetic saturation. In other words, it is difficult to increase the performance of the power conversion module. 
     Therefore, the present disclosure provides a power conversion module and a magnetic device of the power conversion module in order to overcome the drawbacks of the conventional technologies. 
     SUMMARY OF THE INVENTION 
     An object of the present disclosure provides a power conversion module to address the issues encountered by the prior arts. As previously described for the conventional power conversion module, the two opposite ends of each winding groove are exposed to two opposite lateral sides of the E-shaped core, the installation positions of the two coupled inductors formed by two windings and the E-shaped core are different, and the distances from the two coupled inductors to the output terminal of the power conversion module respectively are different. Under this circumstance, the equivalent series resistances of the two coupled inductors are not symmetric, and the currents flowing through the two coupled inductors are not uniformly distributed. Since the DC magnetic fluxes flowing through the lateral legs of the E-shaped core are larger, the lateral legs of the E-shaped core are readily subjected to magnetic saturation. It is difficult to increase the performance of the power conversion module. 
     In accordance with an aspect of the present disclosure, a magnetic device is provided. The magnetic device includes a magnetic core assembly, a first winding and a second winding. The magnetic core assembly includes a top surface, a bottom surface, a first lateral side, a second lateral side, a third lateral side, a fourth lateral side, a middle leg and two lateral legs. The first lateral side, the second lateral side, the third lateral side and the fourth lateral side are disposed between the top surface and the bottom surface. The first lateral side and the third lateral side are opposed to each other. The second lateral side and the fourth lateral side are opposed to each other. The middle leg is disposed between the two lateral legs. A first winding groove is defined by the middle leg and one of the two lateral legs collaboratively. A second winding groove is defined by the middle leg and the other of the two lateral legs collaboratively. Moreover, two opposite ends of the first winding groove are respectively exposed to the first lateral side and the fourth lateral side, and two opposite ends of the second winding groove are respectively exposed to the second lateral side and the third lateral side. At least a part of the first winding is disposed within the first winding groove. At least a part of the second winding is disposed within the second winding groove. 
     In accordance with another aspect of the present disclosure, a power conversion module is provided. The power conversion module includes a magnetic device and a power device. The magnetic device includes a main frame, a magnetic core assembly and a conductive structure. The main frame has a first surface and a second surface, which are opposed to each other. The magnetic core assembly includes a top surface, a bottom surface, a first lateral side, a second lateral side, a third lateral side, a fourth lateral side, a middle leg and two lateral legs. The first lateral side, the second lateral side, the third lateral side and the fourth lateral side are disposed between the top surface and the bottom surface. The first lateral side and the third lateral side are opposed to each other. The second lateral side and the fourth lateral side are opposed to each other. The middle leg is disposed between the two lateral legs. A first winding groove is defined by the middle leg and one of the two lateral legs collaboratively. A second winding groove is defined by the middle leg and the other of the two lateral legs collaboratively. Moreover, two opposite ends of the first winding groove are respectively exposed to the first lateral side and the fourth lateral side, and two opposite ends of the second winding groove are respectively exposed to the second lateral side and the third lateral side. The conductive structure is embedded between the first surface and the second surface of the main frame. The conductive structure is partially exposed to the first lateral side, the second lateral side, the third lateral side or the fourth lateral side of the magnetic core assembly. A portion of the conductive structure is formed as a first winding and a second winding. Moreover, at least a part of the first winding is disposed within the first winding groove, and at least a part of the second winding is disposed within the second winding groove. The power device is disposed on the first surface of the main frame. The power device includes at least one power component. The at least one power component is electrically connected with the conductive structure. A direction of a current flowing the first winding and a direction of a current flowing through the second winding are opposite. 
     From the above descriptions, the present disclosure provides the power conversion module and the magnetic device. In one embodiment, the magnetic core assembly of the magnetic device is specially designed. That is, the two opposite ends of the first winding groove are respectively exposed to the first lateral side and the fourth lateral side. The two opposite ends of the second winding groove are respectively exposed to the second lateral side and the third lateral side. In other words, the two opposite ends of the first winding groove and the two opposite ends of the second winding groove are exposed to four different lateral sides of the magnetic core assembly, respectively. After the two windings are disposed within the two winding grooves to be formed as the coupled inductors, the coupled inductors can be distributed more uniformly. Consequently, the distances of the output terminals from the two coupled inductors to the output positive terminal of the power conversion module respectively are nearly equal. Consequently, the asymmetry of the equivalent series resistances of the two coupled inductors is reduced, and the currents flowing through the two coupled inductors are nearly equal. Since the DC magnetic fluxes flowing through the lateral legs of the magnetic core assembly are reduced, the lateral legs of the magnetic core assembly are not readily subjected to magnetic saturation. Consequently, the performance of the power conversion module is enhanced. 
     The above contents of the present disclosure will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic assembled view illustrating a power conversion module according to a first embodiment of the present disclosure; 
         FIG. 1B  is a schematic assembled view illustrating the power conversion module as shown in  FIG. 1A  and taken along another viewpoint; 
         FIG. 2A  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 1A ; 
         FIG. 2B  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 2A  and taken along another viewpoint; 
         FIG. 3A  is a schematic assembled view illustrating a first exemplary structure of a magnetic core assembly of the power conversion module according to the first embodiment of the present disclosure; 
         FIG. 3B  is a schematic perspective view illustrating the magnetic core assembly as shown in  FIG. 3A ; 
         FIG. 4  is a schematic circuit diagram illustrating a circuitry structure of the power conversion module according to the first embodiment of the present disclosure; 
         FIG. 5A  schematically illustrates a pre-formed structure of the conductive structure in the power conversion module according to the first embodiment of the present disclosure; 
         FIG. 5B  schematically illustrates the conductive structure in the power conversion module according to the first embodiment of the present disclosure; 
         FIG. 6  is a schematic assembled view illustrating a second exemplary structure of a magnetic core assembly of the power conversion module according to the first embodiment of the present disclosure; 
         FIG. 7  is a schematic assembled view illustrating a third exemplary structure of a magnetic core assembly of the power conversion module according to the first embodiment of the present disclosure; 
         FIG. 8A  is a schematic exploded view illustrating a variant example of the magnetic core assembly of  FIG. 2A ; 
         FIG. 8B  is a schematic exploded view illustrating the magnetic core assembly as shown in  FIG. 8A  and taken along another viewpoint; 
         FIG. 9A  is a schematic assembled view illustrating a power conversion module according to a second embodiment of the present disclosure; 
         FIG. 9B  is a schematic assembled view illustrating the power conversion module as shown in  FIG. 9A  and taken along another viewpoint; 
         FIG. 10A  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 9A ; 
         FIG. 10B  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 10A  and taken along another viewpoint; 
         FIG. 11A  is a schematic perspective view illustrating a power conversion module according to a third embodiment of the present disclosure; 
         FIG. 11B  is a schematic assembled view illustrating the power conversion module as shown in  FIG. 11A  and taken along another viewpoint; 
         FIG. 12A  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 11A ; 
         FIG. 12B  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 12A  and taken along another viewpoint; 
         FIG. 13A  is a schematic assembled view illustrating a power conversion module according to a fourth embodiment of the present disclosure; 
         FIG. 13B  is a schematic assembled view illustrating the power conversion module as shown in  FIG. 13A  and taken along another viewpoint; 
         FIG. 14A  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 13A ; 
         FIG. 14B  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 14A  and taken along another viewpoint; 
         FIG. 15A  is a schematic assembled view illustrating a power conversion module according to a fifth embodiment of the present disclosure; 
         FIG. 15B  is a schematic assembled view illustrating the power conversion module as shown in  FIG. 15A  and taken along another viewpoint; 
         FIG. 16A  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 15A ; 
         FIG. 16B  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 16A  and taken along another viewpoint; 
         FIG. 17A  is a schematic perspective view illustrating a power conversion module according to a sixth embodiment of the present disclosure; and 
         FIG. 17B  is a schematic assembled view illustrating the power conversion module as shown in  FIG. 17A  and taken along another viewpoint. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present disclosure will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this disclosure are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed. 
       FIG. 1A  is a schematic assembled view illustrating a power conversion module according to a first embodiment of the present disclosure.  FIG. 1B  is a schematic assembled view illustrating the power conversion module as shown in  FIG. 1A  and taken along another viewpoint.  FIG. 2A  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 1A .  FIG. 2B  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 2A  and taken along another viewpoint.  FIG. 3A  is a schematic assembled view illustrating a first exemplary structure of a magnetic core assembly of the power conversion module according to the first embodiment of the present disclosure.  FIG. 3B  is a schematic perspective view illustrating the magnetic core assembly as shown in  FIG. 3A .  FIG. 4  is a schematic circuit diagram illustrating a circuitry structure of the power conversion module according to the first embodiment of the present disclosure. As shown in  FIGS. 1 to 4 , the power conversion module  1  includes two buck-type power conversion circuits, which are connected with each other in parallel. The power conversion module  1  includes a magnetic device  2  and a power device  5 . 
     The magnetic device  2  includes a magnetic core assembly  20 , a first winding  231   a  and a second winding  231   b.    
     The magnetic core assembly  20  includes a top surface  21 , a bottom surface  22 , a first lateral side  23 , a second lateral side  24 , a third lateral side  25 , a fourth lateral side  26 , a middle leg  27  and two lateral legs  28 . The top surface  21  and the bottom surface  22  are opposed to each other. The first lateral side  23 , the second lateral side  24 , the third lateral side  25  and the fourth lateral side  26  are disposed between the top surface  21  and the bottom surface  22 . The first lateral side  23  and the third lateral side  25  are opposed to each other. The second lateral side  24  and the fourth lateral side  26  are opposed to each other. The second lateral side  24  and the fourth lateral side  26  are disposed between the first lateral side  23  and the third lateral side  25 . The term “two opposed lateral sides” generally refers to that at least one lateral side is formed between the two opposed lateral sides. Preferably but not exclusively, at least one lateral side of the two opposed lateral sides has a flat surface or a curved surface. The middle leg  27  is disposed between the two lateral legs  28 . A first winding groove  29   a  is defined by the middle leg  27  and one of the two lateral legs  28  collaboratively. A second winding groove  29   b  is defined by the middle leg  27  and the other of the two lateral legs  28  collaboratively. The two opposite ends of the first winding groove  29   a  are exposed to the first lateral side  23  and the fourth lateral side  26 , respectively. The two opposite ends of the second winding groove  29   b  are exposed to the second lateral side  24  and the third lateral side  25 , respectively. 
     At least a part of the first winding  231   a  is disposed within the first winding groove  29   a . At least a part of the second winding  231   b  is disposed within the second winding groove  29   b . The directions of the currents flowing through the first winding  231   a  and the second winding  231   b  are opposite. Consequently, the DC magnetic fluxes are superimposed, and the AC magnetic fluxes are cancelled out. In this way, the current ripple is largely decreased, and the equivalent inductance is largely increased. In the embodiment of  FIG. 4 , the first winding  231   a  and the second winding  231   b  are collaboratively formed as two coupled inductors L OA  and L ON . In other embodiment, the two windings  231   a  and  231   b  and the magnetic core assembly  20  are collaboratively formed as a transformer. 
     In an embodiment, the magnetic device  2  further includes a main frame  30  and a conductive structure  40 . For example, the main frame  30  has a hollow box structure or a board structure. In addition, the shape of the main frame  30  matches the shape of the magnetic core assembly  20 . The main frame  30  has a first surface  31  and a second surface  32 , which are opposed to each other. The magnetic core assembly  20  is disposed within the main frame  30 . The top surface  21  of the magnetic core assembly  20  is located beside the first surface  31  of the main frame  30 . The bottom surface  22  of the magnetic core assembly  20  is located beside the second surface  32  of the main frame  30 . The conductive structure  40  is embedded in the main frame  30  and disposed between the first surface  31  and the second surface  32  of the main frame  30 . The conductive structure  40  is arranged around the magnetic core assembly  20 , and partially exposed to the first lateral side  23 , the second lateral side  24 , the third lateral side  25  and the fourth lateral side  26  of the magnetic core assembly  20 . In addition, a portion of the conductive structure  40  is formed as the two windings  231   a  and  231   b.    
     The power device  5  has a plate structure. In an embodiment, the power device  5  is attached on the first surface  31  of the main frame  30 . In addition, the power device  5  includes at least one power component, e.g., two power components  50   a  and  50   b . Each of the power components  50   a  and  50   b  include a half-bridge arm with two switches. As shown in  FIG. 4 , the power component  50   a  includes a half-bridge arm with two switches Q 1A  and Q 2A , and the power component  50   b  includes a half-bridge arm with two switches Q 1N  and Q 2N . Each half-bridge arm is electrically connected with an input capacitor Cin. The power device  5  further includes a controller  51  and a circuit board  52 . The circuit board  52  has a first surface  520  and a second surface  521 , which are opposed to each other. The second surface  521  of the circuit board  52  is located beside the first surface  31  of the main frame  30 . The controller  51  and the power components  50   a  and  50   b  are disposed on the first surface  520  of the circuit board  52 . The controller  51  can control the operations of the power components  50   a  and  50   b.    
     In an embodiment, the two power components  50   a  and  50   b  are symmetrically disposed on the first surface  520  of the circuit board  52  along a diagonal line. In an embodiment, the two power components  50   a  and  50   b  are located at the topmost side of the power conversion module  1  in order to facilitate the installation of a heat sink (not shown). Moreover, at least one power component contact pad  531 , at least one input positive terminal contact pad  532 , at least one output negative terminal contact pad  534 , at least one control signal contact pad  535  and at least one feedback signal contact pad  536  are disposed on the second surface  521  of the circuit board  52 . The at least one power component contact pad  531  is electrically connected with the power component pins SW of the power components  50   a  and  50   b . The input positive terminal contact pad  532  is used as an input positive terminal Vin+. The output negative terminal contact pad  534  is used as an output negative terminal Vo− (i.e., the ground terminal GND of the power conversion module  1 ). The control signal contact pad  535  is used for transferring control signals. The feedback signal contact pad  536  is used for transferring sampling signals. 
     In an embodiment, the power conversion module  1  further includes a pin layer  6 . The pin layer  6  is located beside the second surface  32  of the main frame  30 . In addition, the pin layer  6  is attached on the bottom surface  22  of the magnetic core assembly  20 . The pin layer  6  has a first surface  60  and a second surface  61 , which are opposed to each other. The pin layer  6  includes at least one input positive terminal  62 , at least one output positive terminal  63 , at least one output negative terminal  64 , at least one control signal pin  65  and at least one feedback signal pin  66 , which are disposed on the first surface  60  of the pin layer  6 . The at least one input positive terminal  62  is used as the input positive terminal Vin+. The output negative terminal  64  is used as the output negative terminal Vo− (i.e., the ground terminal GND of the power conversion module  1 ). The output positive terminal  63  is used as an output positive terminal Vo+. These terminals  62 ,  63  and  64  are electrically connected with corresponding external pins that are disposed on the second surface  32  of the main frame  30 . Consequently, the power conversion module  1  can be electrically connected with an external circuit. The control signal pin  65  is used for transferring control signals. The feedback signal pin  66  is used for transferring sampling signals. 
     In an embodiment, the power conversion module  1  further includes an input capacitor Cin. The input capacitor Cin is connected between the input positive terminal and the input negative terminal of the power conversion module  1 . It is preferred that the input capacitor Cin is located near the power components  50   a  and  50   b . In an embodiment, the input capacitor Cin is disposed between the power device  5  and the magnetic device  2 . For example, the input capacitor Cin is disposed on the second surface  521  of the circuit board  52  of the power device  5  and disposed between the power device  5  and the magnetic core assembly  20  of the magnetic device  2 . Alternatively, the input capacitor Cin is disposed between the power device  5  and the main frame  30  of the magnetic device  2 . Generally, during the switching processes of the power components  50   a  and  50   b , the parasitic parameters between the input capacitor Cin and the power components  50   a ,  50   b  and the power components equivalent parameters may result in high-frequency parasitic oscillation. The high-frequency parasitic oscillation affects the switching processes and the power loss of the power components  50   a  and  50   b . Since the input capacitor Cin is located near the power components  50   a  and  50   b , the influence of the parasitic parameters can be reduced. In this way, the volume of the power conversion module  1  can be reduced, and the overall power density of the power conversion module  1  can be increased. For reducing the distributed inductance between the input capacitor Cin and each half-bridge arm, the input capacitor Cin is disposed between the two half-bridge arms and the two coupled inductors. Moreover, the projection region of the input capacitor Cin with respect to the horizontal plane and the projection region of the magnetic core assembly  20  with respect to the horizontal plane are partially overlapped with each other. 
     In an embodiment, the power conversion module  1  further includes an output capacitor Co. Preferably, the output capacitor Co is disposed between the magnetic device  2  and the pin layer  6 . It is noted that the installation position of the output capacitor Co is not restricted. For example, in other embodiment, the output capacitor Co is disposed on a system board (not shown). That is, the output capacitor Co is located outside the power conversion module  1 . In an embodiment, the second terminal of the output capacitor Co is connected with the output positive terminal  63 , and the first terminal of the output capacitor Co is connected with the output negative terminal  64 . 
     As previously described, the magnetic device of the conventional power conversion module is usually equipped with an E-shaped core, and the E-shaped core has two winding grooves. Since two opposite ends of each winding groove are exposed to two opposite lateral sides of the E-shaped core, some drawbacks occur. In one embodiment, the magnetic core assembly  20  of the magnetic device  2  of the power conversion module  1  is specially designed. That is, the two opposite ends of the first winding groove  29   a  are respectively exposed to the first lateral side  23  and the fourth lateral side  26 , and the two opposite ends of the second winding groove  29   b  are respectively exposed to the second lateral side  24  and the third lateral side  25 . In other words, the two opposite ends of the first winding groove  29   a  and the two opposite ends of the second winding groove  29   b  are exposed to four different lateral sides of the magnetic core assembly  20 , respectively. After the two windings  231   a  and  231   b  are disposed within the two winding grooves  29   a  and  29   b  to be formed as the coupled inductors, the coupled inductors can be distributed more uniformly. Consequently, the distances from the output terminals of the two coupled inductors (e.g., the output positive terminal contact surfaces  43 ) to the output positive terminal Vo+ of the power conversion module  1  (e.g., the output terminal  613  as shown in  FIG. 2B ) are nearly equal. In addition, the asymmetry of the equivalent series resistances of the two coupled inductors is reduced, and the currents flowing through the two coupled inductors are nearly equal. Since the DC magnetic fluxes flowing through the lateral legs of the magnetic core assembly are reduced, the lateral legs of the magnetic core assembly are not readily subjected to magnetic saturation. Consequently, the performance of the power conversion module  1  is enhanced. 
     Moreover, the first terminal of the first winding  231   a  is electrically connected with one of the two power components  50   a  and  50   b  (i.e., one of the two half-bridge arms), and the first terminal of the second winding  231   b  is electrically connected with the other of the two power components  50   a  and  50   b  (i.e., the other of the two half-bridge arms). Moreover, the projection region of one half-bridge arm with respect to the circuit board  52  and the projection region of the other half-bridge arm with respect to the circuit board  52  are partially overlapped with each other. 
     In this embodiment, the magnetic core assembly  20  has a hexahedral structure. That is, a second side of the first lateral side  23  is connected with a first side of the second lateral side  24 , a second side of the second lateral side  24  is connected with a first side of the third lateral side  25 , a second side of the third lateral side  25  is connected with a first side of the fourth lateral side  26 , and a second side of the fourth lateral side  26  is connected with a first side of the first lateral side  23 . Preferably but not exclusively, the angle between the first lateral side  23  and the second lateral side  24  or the angle between the first lateral side  23  and the fourth lateral side  26  is smaller than or equal to 120 degrees. Preferably but not exclusively, the first winding groove  29   a  and the second winding groove  29   b  are in parallel with each other. As shown in  FIG. 3B , the line A passing through the two opposite ends of the first winding groove  29   a  are not perpendicular to the first lateral side  23  and the fourth lateral side  26 , and the line B passing through the two opposite ends of the second winding groove  29   b  are not perpendicular to the second lateral side  24  and the third lateral side  25 . 
       FIG. 5A  schematically illustrates a pre-formed structure of the conductive structure in the power conversion module according to the first embodiment of the present disclosure.  FIG. 5B  schematically illustrates the conductive structure in the power conversion module according to the first embodiment of the present disclosure. In accordance with a feature of the present disclosure, the conductive structure  40  includes at least one copper layer or at least one copper block, and the conductive structure  40  is previously embedded in the main frame  30 . As shown in  FIG. 5A , a pre-formed structure  23   a  (e.g., a copper block) is embedded in a circuit board (not shown). After the pre-formed structure  23   a  undergoes a controlled deep milling process, the pre-formed structure  23   a  is milled as the conductive structure  40  as shown in  FIG. 5B . 
     Please refer to  FIG. 5B . The conductive structure  40  includes two first connection parts  241  and two second connection parts  242 . The first connection parts  241  and the two second connection parts  242  are embedded in at least two sidewalls of the main frame  30  and disposed between the first surface  31  and the second surface  32  of the main frame  30 . The first winding  231   a  and the second winding  231   b  are connected between the corresponding first connection parts  241  and the corresponding second connection parts  242 , respectively. The first end surfaces of the first connection parts  241  are partially exposed to the first surface  31  of the main frame  30  and formed as power component terminal contact surfaces  41 . The power component terminal contact surfaces  41  are connected with the power component pins SW of the power components  50   a  and  50   b . The second end surfaces of the first connection parts  241  are selectively exposed to the second surface  32  of the main frame  30 . The second end surfaces of the second connection parts  242  are partially exposed to the second surface  32  of the main frame  30  and formed as the output positive terminal contact surfaces  43  of the power conversion module  1 . The output positive terminal contact surfaces  43  are connected with the output positive terminal Vo+ of the power conversion module  1  and connected with the second terminal of the output capacitor Co. The first end surfaces of the second connection parts  242  are selectively exposed to the first surface  31  of the main frame  30 , but not limited thereto. 
     In an embodiment, the first surface  31  of the main frame  30  is higher than the top surface  21  of the magnetic core assembly  20 , and the second surface  32  of the main frame  30  is lower than the bottom surface  22  of the magnetic core assembly  20 . In an embodiment, the conductive structure  40  and the main frame  30  are integrated as a one-piece structure by using a plastic molding process. Preferably but not exclusively, the main frame  30  is made of epoxy resin or PCB material. 
     The conductive structure  40  further includes two third connection parts  243  and two fourth connection parts  244 . The two third connection parts  243  and the two fourth connection parts  244  are embedded in at least two sidewalls of the main frame  30  and disposed between the first surface  31  and the second surface  32  of the main frame  30 . The first end surfaces of the third connection parts  243  are partially exposed to the first surface  31  of the main frame  30  and formed as input positive terminal contact surfaces  42 . The first end surfaces of the fourth connection parts  244  are partially exposed to the first surface  31  of the main frame  30  and formed as output negative terminal contact surfaces  44 . The second end surfaces of the third connection parts  243  are partially exposed to the second surface  32  of the main frame  30  and formed as the input positive terminal contact surfaces  42 . The second end surfaces of the fourth connection parts  244  are partially exposed to the second surface  32  of the main frame  30  and formed as the output negative terminal contact surfaces  44 . The input positive terminal contact surfaces  42  are connected with the input positive terminal Vin+. The output negative terminal contact surfaces  44  are connected with the output negative terminal Vo−. In addition, the output negative terminal contact surfaces  44  are connected with the GND mesh of the power device  5  and connected with the GND mesh of the pin layer  6 . 
     The conductive structure  40  further includes some additional connection parts. The first end surfaces of the additional connection parts are partially exposed to the first surface  31  of the main frame  30 . The second end surfaces of the additional connection parts are partially exposed to the second surface  32  of the main frame  30 . Consequently, control signal pin contact surfaces  45  and feedback signal pin contact surfaces  46  (see  FIG. 2A ) are formed. The power device  5  and the pin layer  6  of the power conversion module  1  (or the at least one power component and the system board) are in communication with each other through the control signal pin contact surfaces  45 . The feedback signal pin contact surfaces  46  are used for transferring sampling signals. 
     The at least one input positive terminal  62  of the pin layer  6  is electrically connected with the corresponding input positive terminal contact surface  42 . The at least one output positive terminal  63  is electrically connected with the corresponding output positive terminal contact surface  43 . The at least one output negative terminal  64  is electrically connected with the corresponding output negative terminal contact surface  44 . The at least one control signal pin  65  is electrically connected with the corresponding control signal pin contact surface  45 . The at least one feedback signal pin  66  is electrically connected with the corresponding feedback signal pin contact surface  46 . The at least one input positive terminal contact pad  532  of the power device  5  is electrically connected with the corresponding input positive terminal contact surface  42 . The at least one power component contact pad  531  is electrically connected with the corresponding power component terminal contact surface  41 . The at least one output negative terminal contact pad  534  is electrically connected with the corresponding output negative terminal contact surface  44 . The at least one control signal contact pad  535  is electrically connected with the corresponding control signal pin contact surface  45 . The at least one feedback signal contact pad  536  is electrically connected with the corresponding feedback signal pin contact surface  46 . 
     In another embodiment, the output positive terminal contact surfaces  43 , the input positive terminal contact surfaces  42 , the output negative terminal contact surfaces  44 , the control signal pin contact surfaces  45  and the feedback signal pin contact surfaces  46  are used as external pins of the power conversion module  1  and directly connected with the system board. Under this circumstance, the power conversion module  1  omits the pin layer, and thus the thickness of the power conversion module  1  is reduced. 
     In one embodiment, the material of the magnetic core assembly  20  is specially determined. Preferably, the material of the middle leg  27  is different from the material of the rest of the magnetic core assembly  20 . For example, the middle leg  27  is made of iron powder with distributed air gap, and the rest of the magnetic core assembly  20  is made of ferrite. Consequently, the core loss of the magnetic core assembly  20  is decreased, and the core loss of the middle leg  27  is not obviously increased. In an embodiment, the cross section area of the middle leg  27  and the cross section area of the lateral leg  28  are equal. 
     Please refer to  FIGS. 2A, 2B and 3A  again. In this embodiment, the magnetic core assembly  20  includes two E-shaped cores  200 . Each E-shaped core  200  includes a middle post and two lateral posts. The middle post is a partial structure of the middle leg  27 . The two lateral posts are partial structures of the corresponding lateral legs  28 . The two E-shaped cores  200  are opposed to each other. The outer surface of one E-shaped core  200  is the top surface  21  of the magnetic core assembly  20 . The outer surface of the other E-shaped core  200  is the bottom surface  22  of the magnetic core assembly  20 . 
       FIG. 6  is a schematic assembled view illustrating a second exemplary structure of a magnetic core assembly of the power conversion module according to the first embodiment of the present disclosure. In this embodiment, the middle leg  27  of the magnetic core assembly  20  includes an air gap  270 . For example, the air gap  270  is located at an upper portion of the middle leg  27  and located near the top surface  21  of the magnetic core assembly  20 . Alternatively, the air gap  270  is located at a lower portion of the middle leg  27  and located near the bottom surface  22  of the magnetic core assembly  20 . Alternatively, the air gap  270  is located at a middle region of the middle leg  27 . Due to this structural design, the magnetic resistance of the middle leg  27  is increased, and the magnetic densities of the middle leg  27  and the lateral legs  28  are increased. Consequently, the performance of the magnetic device  2  to withstand the current saturation is enhanced. 
       FIG. 7  is a schematic assembled view illustrating a third exemplary structure of a magnetic core assembly of the power conversion module according to the first embodiment of the present disclosure. In this embodiment, the magnetic core assembly  20  includes an I-shaped core  201  and an E-shaped core  202 . The E-shaped core  202  includes a middle post and two lateral posts. The middle post is the middle leg  27 . The two lateral posts are the corresponding lateral legs  28 . The I-shaped core  201  and the E-shaped core  202  are opposed to each other. The outer surface of one of the I-shaped core  201  and the E-shaped core  202  is the top surface  21  of the magnetic core assembly  20 . The outer surface of the other of the I-shaped core  201  and the E-shaped core  202  is the bottom surface  22  of the magnetic core assembly  20 . 
       FIG. 8A  is a schematic exploded view illustrating a variant example of the magnetic core assembly of  FIG. 2A .  FIG. 8B  is a schematic exploded view illustrating the magnetic core assembly as shown in  FIG. 8A  and taken along another viewpoint. It is noted that the configuration of the magnetic core assembly is not restricted to the hexahedral structure. In the embodiment of  FIGS. 8A and 8B , the magnetic core assembly  20   a  has an octahedral structure. The magnetic core assembly  20   a  has a top surface  80 , a bottom surface  81 , a first lateral side  82 , a second lateral side  83 , a third lateral side  84 , a fourth lateral side  85 , a fifth lateral side  86  and a sixth lateral side  87 . The fifth lateral side  86  and the sixth lateral side  87  are disposed between the top surface  80  and the bottom surface  81 . The fifth lateral side  86  is disposed between the first lateral side  82  and the second lateral side  83 . The sixth lateral side  87  is disposed between the third lateral side  84  and the fourth lateral side  85 . 
     The present disclosure further provides other possible embodiments of the power conversion modules. Component parts and elements corresponding to those of the first embodiment are designated by identical numeral references, and detailed descriptions thereof are omitted. 
       FIG. 9A  is a schematic assembled view illustrating a power conversion module according to a second embodiment of the present disclosure.  FIG. 9B  is a schematic assembled view illustrating the power conversion module as shown in  FIG. 9A  and taken along another viewpoint.  FIG. 10A  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 9A .  FIG. 10B  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 10A  and taken along another viewpoint. In comparison with the power conversion module  1  of the first embodiment, the two power components  50   a  and  50   b  (i.e., the two half-bridge arms) of the power conversion module  1   a  in this embodiment are included in a package unit  7 . The package unit  7  is welded on the first surface  520  of the circuit board  52  of the power device  5 . Moreover, the power conversion module  1   a  further includes at least one output capacitor  70  (i.e., the output capacitor Co as shown in  FIG. 4 ). The output capacitor  70  is disposed on the first surface  60  of the pin layer  6 . That is, the output capacitor  70  is disposed between the magnetic core assembly  20  and the pin layer  6 . Consequently, the ripple of the output voltage is reduced. Moreover, the projection region of the output capacitor Co with respect to the horizontal plane and the projection region of the magnetic core assembly  20  with respect to the horizontal plane are partially overlapped with each other. 
       FIG. 11A  is a schematic perspective view illustrating a power conversion module according to a third embodiment of the present disclosure.  FIG. 11B  is a schematic assembled view illustrating the power conversion module as shown in  FIG. 11A  and taken along another viewpoint.  FIG. 12A  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 11A .  FIG. 12B  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 12A  and taken along another viewpoint. In comparison with the power conversion module  1  of the first embodiment, the two power components  50   a  and  50   b  (i.e., the two half-bridge arms) and the controller  51  of the power conversion module  1   b  in this embodiment are embedded in the circuit board  52 . Consequently, the difficulty of performing the printed circuit board assembly (PCBA) is reduced. Since no other electronic components are disposed on the first surface  520  of the circuit board  52 , a heat sink (not shown) can be disposed on the first surface  520  of the circuit board  52  more easily. 
       FIG. 13A  is a schematic assembled view illustrating a power conversion module according to a fourth embodiment of the present disclosure.  FIG. 13B  is a schematic assembled view illustrating the power conversion module as shown in  FIG. 13A  and taken along another viewpoint.  FIG. 14A  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 13A .  FIG. 14B  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 14A  and taken along another viewpoint. In comparison with the power conversion module  1  of the first embodiment, the magnetic device  2  and the circuit board  52  in the power conversion module  1   c  of this embodiment are included in a package structure  8 . Consequently, the height of the power conversion module  1   c  is reduced. The package structure  8  has a first surface  88  and a second surface  89 , which are opposed to each other. The first surface  88  of the package structure  8  is located near the first surface (not shown) of the circuit board  52 . In addition, the two power components  50   a  and  50   b  (i.e., the two half-bridge arms) and the controller  51  are welded on the first surface  88  of the package structure  8 . The second surface  89  of the package structure  8  is attached to the pin layer  6 . In addition, the input positive terminal contact surfaces, the output negative terminal contact surfaces, the control signal pin contact surfaces and the feedback signal pin contact surfaces are formed on the second surface  89  of the package structure  8 . 
       FIG. 15A  is a schematic assembled view illustrating a power conversion module according to a fifth embodiment of the present disclosure.  FIG. 15B  is a schematic assembled view illustrating the power conversion module as shown in  FIG. 15A  and taken along another viewpoint.  FIG. 16A  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 15A .  FIG. 16B  is a schematic exploded view illustrating the power conversion module as shown in  FIG. 16A  and taken along another viewpoint. In comparison with the power conversion module  1   c  of  FIG. 13A , the magnetic device  2 , the circuit board  52 , two power components  50   a  and  50   b  (i.e., the two half-bridge arms) and the controller  51  in the power conversion module  1   d  of this embodiment are included in a package structure  9 . Consequently, the height of the power conversion module  1   d  is further reduced. The package structure  9  has a first surface  90  and a second surface  91 , which are opposed to each other. The first surface  90  of the package structure  9  is located near the first surface (not shown) of the circuit board  52 . Since no other electronic components are disposed on the first surface  90  of the package structure  9 , a heat sink (not shown) can be disposed on the first surface  90  of the package structure  9  more easily. The second surface  91  of the package structure  9  is attached to the pin layer  6 . In addition, the input positive terminal contact surfaces, the output negative terminal contact surfaces, the control signal pin contact surfaces and the feedback signal pin contact surfaces are formed on the second surface  91  of the package structure  9 . 
       FIG. 17A  is a schematic perspective view illustrating a power conversion module according to a sixth embodiment of the present disclosure.  FIG. 17B  is a schematic assembled view illustrating the power conversion module as shown in  FIG. 17A  and taken along another viewpoint. In comparison with the power conversion module  1   d  of  FIG. 15A , the magnetic device  2 , the circuit board  52  and the pin layer  6  in the power conversion module  1   e  of this embodiment are included in a package structure  9   a . Consequently, the height of the power conversion module  1   e  is further reduced. The package structure  9   a  has a first surface  9   b  and a second surface  9   c , which are opposed to each other. The first surface  9   b  of the package structure  9   a  is located near the first surface (not shown) of the circuit board  52 . Since no other electronic components are disposed on the first surface  9   b  of the package structure  9   a , a heat sink (not shown) can be disposed on the first surface  9   b  of the package structure  9   a  more easily. 
     In an embodiment, the two power components  50   a  and  50   b  (i.e., the two half-bridge arms) and the controller  51  disposed on the circuit board  52  are also included in the package structure  9   a . Moreover, the top surface of each of the two power components  50   a  and  50   b  (i.e., the two half-bridge arms) is lower than the first surface  9   b  of the package structure  9   a . In other embodiment, the two power components  50   a  and  50   b  (i.e., the two half-bridge arms) and the controller  51  are disposed on the first surface  9   b  of the package structure  9   a.    
     From the above descriptions, the present disclosure provides the power conversion module and the magnetic device. In one embodiment, the magnetic core assembly of the magnetic device is specially designed. That is, the two opposite ends of the first winding groove are respectively exposed to the first lateral side and the fourth lateral side. The two opposite ends of the second winding groove are respectively exposed to the second lateral side and the third lateral side. In other words, the two opposite ends of the first winding groove and the two opposite ends of the second winding groove are exposed to four different lateral sides of the magnetic core assembly, respectively. After the two windings are disposed within the two winding grooves to be formed as the coupled inductors, the coupled inductors can be distributed more uniformly. Consequently, the distances between the output terminals of the two coupled inductors and the output positive terminal of the power conversion module are nearly equal. Consequently, the asymmetry of the equivalent series resistances of the two coupled inductors is reduced, and the currents flowing through the two coupled inductors are nearly equal. Since the DC magnetic fluxes flowing through the lateral legs of the magnetic core assembly are reduced, the lateral legs of the magnetic core assembly are not readily subjected to magnetic saturation. Consequently, the performance of the power conversion module is enhanced. 
     While the disclosure has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the disclosure needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.