Patent Publication Number: US-2022220931-A1

Title: Wave energy conversion device and dual-axial wave energy conversion device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an energy conversion device, and more specifically, to a wave energy conversion device and dual-axial wave energy conversion device. 
     2. Description of the Prior Art 
     Wave energy conversion technology is used for converting wave energy into electricity. The wave energy is unstable and irregular but is inexhaustible in supply and always available for use. Therefore, wave energy conversion has a greater potential than any other ocean energy conversion, and it becomes an important topic in the field to reduce maintenance cost, improve reliability, and stabilize an amount of electricity generation of the wave energy conversion. 
     SUMMARY OF THE INVENTION 
     Therefore, it is an objective of the present invention to provide a wave energy conversion device and dual-axial wave energy conversion device for solving the aforementioned problem. 
     In order to achieve the aforementioned objective, the present invention discloses a wave energy conversion device including a permanent magnet generator, a first driving component and a second driving component. The permanent magnet generator includes a stator structure and a rotor structure. The stator structure includes a stator body. The rotor structure includes a rotor body. The rotor body is disposed inside the stator body in a swinging manner or a rotating manner. The first driving component is coupled to the rotor structure. The second driving component is coupled to the stator structure. 
     According to an embodiment of the present invention, a plurality of stator slots are formed on the stator body. A plurality of rotor slots are formed on the rotor body. A central axis of the stator body is coincided with a central axis of the rotor body. The plurality of stator slots are arranged along a circumferential direction of the stator body, and the plurality of rotor slots are arranged along a circumferential direction of the rotor body. 
     According to an embodiment of the present invention, the rotor structure further includes a plurality of permanent magnets respectively disposed inside the plurality of rotor slots. A number of the plurality of permanent magnets is identical to a number of the plurality of rotor slots, and the stator structure further includes a plurality of stator coils wrapped around the plurality of stator slots. 
     According to an embodiment of the present invention, the stator structure further includes a shell, and the stator body is fixedly disposed inside the shell. 
     According to an embodiment of the present invention, the rotor structure further includes a connecting shaft coupled to the rotor body. The connecting shaft passes through the shell and is coupled to the first driving component, and the shell is coupled to the second driving component. 
     According to an embodiment of the present invention, each of the stator body and the rotor body is formed by a plurality of silicon steel sheets. 
     According to an embodiment of the present invention, each of the first driving component and the second driving component is a floating component. 
     According to an embodiment of the present invention, the floating component includes a first portion and a second portion, and the second portion is movable relative to the first portion to increase or reduce a total length of the floating component. 
     In order to achieve the aforementioned objective, the present invention further discloses a dual-axial wave energy conversion device including a first permanent magnet generator, a second permanent magnet generator, a first driving component and a second driving component. The first permanent magnet generator includes a first stator structure and a first rotor structure. The first stator structure includes a first stator body. The first rotor structure includes a first rotor body. The first rotor body is disposed inside the first stator body in a swinging manner or in a rotating manner. The second permanent magnet generator includes a second stator structure and a second rotor structure. The second stator structure includes a second stator body. The second rotor structure includes a second rotor body. The second rotor body is disposed inside the second stator body in a swinging manner or in a rotating manner. A swinging direction or a rotating direction of the second rotor body is different from a swinging direction or a rotating direction of the first rotor body. The first driving component is coupled to the first permanent magnet generator. The second driving component is coupled to the second permanent magnet generator. 
     According to an embodiment of the present invention, a plurality of first stator slots are formed on the first stator body. A plurality of first rotor slots are formed on the first rotor body. A central axis of the first stator body is coincided with a central axis of the first rotor body. The plurality of first stator slots are arranged along a circumferential direction of the first stator body. The plurality of first rotor slots are arranged along a circumferential direction of the first rotor body. A plurality of second stator slots are formed on the second stator body. A plurality of second rotor slots are formed on the second rotor body. A central axis of the second stator body is coincided with a central axis of the second rotor body. The plurality of second stator slots are arranged along a circumferential direction of the second stator body, and the plurality of second rotor slots are arranged along a circumferential direction of the second rotor body. 
     According to an embodiment of the present invention, the first rotor structure further includes a plurality of first permanent magnets respectively disposed inside the plurality of first rotor slots. A number of the plurality of first permanent magnets is identical to a number of the plurality of first rotor slots. The first stator structure further includes a plurality of first stator coils wrapped around the plurality of first stator slots. The second rotor structure further includes a plurality of second permanent magnets respectively disposed inside the plurality of second rotor slots. A number of the plurality of second permanent magnets is identical to a number of the plurality of second rotor slots, and the second stator structure further includes a plurality of second stator coils wrapped around the plurality of second stator slots. 
     According to an embodiment of the present invention, the first stator structure further includes a first shell. The first stator body is fixedly disposed inside the first shell. The second stator structure further includes a second shell, and the second stator body is fixedly disposed inside the second shell. 
     According to an embodiment of the present invention, the first rotor structure further includes a first connecting shaft coupled to the first rotor body. The first connecting shaft passes through the first shell. The second rotor structure further includes a second connecting shaft coupled to the second rotor body, and the second connecting shaft passes through the second shell. 
     According to an embodiment of the present invention, each of the first stator body, the first rotor body, the second stator body and the second rotor body is formed by a plurality of silicon steel sheets. 
     According to an embodiment of the present invention, each of the first driving component and the second driving component is a floating component. 
     According to an embodiment of the present invention, the floating component includes a first portion and a second portion, and the second portion is movable relative to the first portion to increase or reduce a total length of the floating component. 
     According to an embodiment of the present invention, the dual-axial wave energy conversion device further includes at least one extending and retracting assembly configured to move at least one of the first driving component and the second driving component for increasing or reducing a distance between the first driving component and the second driving component. 
     In summary, the wave energy conversion device of the present invention utilizes a coupling connection of the first driving component and the rotor structure and a coupling connection of the second driving component and the stator structure to convert a wave movement into a rotating movement or a swinging movement of the rotor body relative to the stator body by the first driving component and the second driving component. Furthermore, a ratio of the number of the plurality of rotor slots to a number of the plurality of stator slots can be 8:9, and the number of the plurality of the rotor slots and the number of the plurality of the stator slots can be at least equal to 64 and 72, respectively. Due to the aforementioned configuration, the wave energy conversion device only requires a low speed and a small angle of the rotating movement or the swinging movement of the rotor body relative to the stator body, for generating electricity. Therefore, even if amplitude of the wave movement is small, the wave energy conversion device can generate electricity stably, which improves reliability and stability of electricity generation. Besides, the wave energy conversion device has simple structure, which reduces maintenance cost. In addition, the dual-axial wave energy conversion of the present invention utilizes a coupling connection of the first driving component and the first permanent magnet generator, a coupling connection of the second driving component and the second permanent magnet generator and a coupling connection of the first permanent magnet generator and the second permanent magnet generator to convert wave movements along different directions into a rotating movement or a swinging movement of the first rotor body relative to the first stator body and a rotating movement or a swinging movement of the second rotor body relative to the second stator body by the first driving component and the second driving component. Moreover, the structure of each of the first permanent magnet generator and the second permanent magnet generator of the dual-axial wave energy conversion device is similar to the one of the permanent magnet generator of the wave energy conversion device. Due to the aforementioned configuration, the dual-axial wave energy conversion device only requires a low speed and a small angle of the rotating movement or the swinging movement of the first rotor body relative to the first stator body and a low speed and a small angle of the rotating movement or the swinging movement of the second rotor body relative to the second stator body but does not require a fixed wave direction, for generating electricity. Therefore, even if amplitude of the wave movement is small and the wave direction is changed by wind, the dual-axial wave energy conversion device still can generate electricity stably, which improves reliability and stability of electricity generation. Besides, the dual-axial wave energy conversion device has simple structure, which reduces maintenance cost. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a wave energy conversion device according to a first embodiment of the present invention. 
         FIG. 2  is an exploded diagram of the wave energy conversion device according to the first embodiment of the present invention. 
         FIG. 3  is a diagram of a permanent magnet generator according to the first embodiment of the present invention. 
         FIG. 4  is a partial diagram of the permanent magnet generator according to the first embodiment of the present invention. 
         FIG. 5  is a partial exploded diagram of the permanent magnet generator according to the first embodiment of the present invention. 
         FIG. 6  is a partial sectional diagram of the permanent magnet generator according to the first embodiment of the present invention. 
         FIG. 7  is a schematic diagram of a wave energy conversion device according to a second embodiment of the present invention. 
         FIG. 8  is an exploded diagram of the wave energy conversion device according to the second embodiment of the present invention. 
         FIG. 9  is a schematic diagram of a dual-axial wave energy conversion device according to a third embodiment of the present invention. 
         FIG. 10  is an exploded diagram of the dual-axial wave energy conversion device according to the third embodiment of the present invention. 
         FIG. 11  is a schematic diagram of a dual-axial wave energy conversion device according to a fourth embodiment of the present invention. 
         FIG. 12  is an exploded diagram of the dual-axial wave energy conversion device according to the fourth embodiment of the present invention. 
         FIG. 13  and  FIG. 14  are schematic diagrams of a dual-axial wave energy conversion device in different states according to a fifth embodiment of the present invention. 
         FIG. 15  is a schematic diagram of a dual-axial wave energy conversion device according to a sixth embodiment of the present invention. 
         FIG. 16  is a diagram of a first driving component and a second driving component according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top”, “bottom”, “front”, “back”, etc., is used with reference to the orientation of the Figure(s) being described. The components of the present invention can be positioned in a number of different orientations. As such, the directional terminology is used for purposes of illustration and is in no way limiting. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. Also, the term “connect” or “couple” is intended to mean either an indirect or direct electrical/mechanical connection. Thus, if a first device is connected to or coupled to a second device, that connection may be through a direct electrical/mechanical connection, or through an indirect electrical/mechanical connection via other devices and connections. 
     Please refer to  FIG. 1  to  FIG. 6 .  FIG. 1  is a schematic diagram of a wave energy conversion device  1 A according to a first embodiment of the present invention.  FIG. 2  is an exploded diagram of the wave energy conversion device  1 A according to the first embodiment of the present invention.  FIG. 3  is a diagram of a permanent magnet generator  11 A according to the first embodiment of the present invention.  FIG. 4  is a partial diagram of the permanent magnet generator  11 A according to the first embodiment of the present invention.  FIG. 5  is a partial exploded diagram of the permanent magnet generator  11 A according to the first embodiment of the present invention.  FIG. 6  is a partial sectional diagram of the permanent magnet generator  11 A according to the first embodiment of the present invention. As shown in FIG.  1  to  FIG. 2 , the wave energy conversion device  1 A includes the permanent magnet generator  11 A, a first driving component  12 A and a second driving component  13 A. The permanent magnet generator  11 A includes a stator structure  111 A and a rotor structure  112 A. The rotor structure  112 A can rotate or swing relative to the stator structure  111 A. The first driving component  12 A is coupled to the rotor structure  112 A. The second driving component  13 A is coupled to the stator structure  111 A. Each of the first driving component  12 A and the second driving component  13 A can be a floating component, such as a buoy. However, the present invention is not limited thereto. A wave movement can drive the first driving component  12 A and the second driving component  13 A to move to drive the rotor structure  112 A to rotate or swing relative to the stator structure  111 A, so that the stator structure  111 A can generate an electrical current by a magnetic field variation during a rotating movement or a swinging movement of the rotor structure  112 A relative to the stator structure  111 A, so as to achieve a purpose of electricity generation. 
     As shown in  FIG. 4  to  FIG. 6 , the stator structure  111 A includes a stator body  1111 A, a plurality of stator coils  1112 A and a shell  1113 A. The stator body  1111 A is fixedly disposed inside the shell  1113 A. A plurality of stator slots  1114 A are formed on the stator body  1111 A. The plurality of stator coils  1112 A are wrapped around the plurality of stator slots  1114 A for generating the electrical current. Preferably, the stator body  1111 A can be a circular column and made of magnetically conductive material, such as silicon steel. Specifically, the stator body  1111 A can be formed by a plurality of stacked ring-shaped silicon steel sheets. 
     The rotor structure  112 A includes a rotor body  1121 A and a plurality of permanent magnets  1122 A. The rotor body  1121 A is disposed inside the stator body  1111 A in a swinging manner or a rotating manner. A plurality of rotor slots  1123 A are formed on the rotor body  1121 A. The plurality of permanent magnets  1122 A are disposed inside the plurality of rotor slots  1123 A, respectively, and the plurality of permanent magnets  1122 A are configured to cause a magnetic flux variation when the rotor body  1121 A rotates or swings. Preferably, a number of the plurality of permanent magnets  1122 A can be identical to a number of the plurality of rotor slots  1123 A, that is, each of the plurality of permanent magnets  1122 A is installed inside the corresponding rotor slot  1123 A. However, in another embodiment, the number of the plurality of permanent magnets can be less than the number of the plurality of rotor slots. Preferably, the rotor body  1121 A can be a circular column and made of magnetically conductive material, such as silicon steel. Specifically, the rotor body  1121 A can be formed by a plurality of stacked ring-shaped silicon steel sheets. 
     A central axis of the stator body  1111 A is collided with a central axis of the rotor body  1121 A. The plurality of stator slots  1114 A are arranged along a circumferential direction C 1  of the stator body  1111 A, and the plurality of rotor slots  1123 A are arranged along a circumferential direction C 2  of the rotor body  1121 A. Preferably, the plurality of stator slots  1114 A can be arranged along the circumferential direction C 1  of the stator body  1111 A at equal intervals, and the plurality of rotor slots  1123 A can be arranged along the circumferential direction C 2  of the rotor body  1121 A at equal intervals. 
     It should be noticed that, in the present invention, as shown in  FIG. 6 , a ratio of the number of the plurality of rotor slots  1123 A to a number of the plurality of stator slots  1114 A is 8:9. Preferably, the number of the plurality of rotor slots  1123 A is at least equal to 64, and the number of the plurality of stator slots  1114 A is at least equal to 72. Due to the aforementioned configuration, the permanent magnet generator  11 A of the present invention not only can generate electricity stably even in a condition of a low speed and a small angle of the rotating movement or the swinging movement of the rotor body  1121 A relative to the stator body  1111 A but also has better efficiency of electricity generation, which facilitates wave energy conversion. 
     However, the structure of the permanent magnet generator is not limited to the aforementioned embodiment. It depends on practical demands. For example, in another embodiment, each of the rotor body and the stator body can be formed by a plurality of stacked sector-shaped silicon steel sheets. 
     As shown in  FIG. 1  to  FIG. 5 , in order to achieve a coupling connection of the first driving component  12 A and the rotor structure  112 A, the rotor structure  112 A further includes a connecting shaft  1124 A coupled to the rotor body  1121 A. The connecting shaft  1124 A passes through the shell  1113 A and is connected to the first driving component  12 A. Furthermore, in order to achieve a coupling connection of the second driving component  13 A and the stator structure  111 A, the shell  1113 A of the stator structure  111 A is connected to the second driving component  13 A. 
     In this embodiment, the wave energy conversion device  1 A utilizes the coupling connection of the first driving component  12 A and the rotor structure  112 A and the coupling connection of the second driving component  13 A and the stator structure  111 A to convert the wave movement into the rotating movement or the swinging movement of the rotor body  1121 A relative to the stator body  1111 A by the first driving component  12 A and the second driving component  13 A. Furthermore, the ratio of the number of the plurality of rotor slots  1123 A to the number of the plurality of stator slots  1114 A can be 8:9, and the number of the plurality of the rotor slots  1123 A and the number of the plurality of the stator slots  1114 A can be at least equal to 64 and 72, respectively. Due to the aforementioned configuration, the wave energy conversion device  1 A only requires a low speed and a small angle of the rotating movement or the swinging movement of the rotor body  1121 A relative to the stator body  1111 A, for generating electricity. In other words, in the condition of the low speed and the small angle of the rotating movement or the swinging movement of the rotor body  1121 A relative to the stator body  1111 , the magnetic flux variation of the permanent magnet generator  11 A of the wave energy conversion device  1 A still can cause the stator structure  111 A to generate an electrical current. Therefore, even if amplitude of the wave movement is small, the wave energy conversion device  1 A still can generate electricity stably, which improves reliability and stability of electricity generation. Besides, the wave energy conversion device  1 A has simple structure, which reduces maintenance cost. 
     Specifically, for example, when the number of the plurality of the rotor slots  1123 A and the number of the plurality of the stator slots  1114 A are equal to 64 and 72, respectively, the stator coils  1112 A can generate the electrical current as long as the angle of the rotating movement or the swinging movement of the rotor body  1121 A relative to the stator body  1111 A reaches 22.5 degrees. Therefore, even if the rotor body  1121 A is driven by the waves to swing relative to the stator body  1111 A at a small angle back and forth instead of rotating relative to the stator body  1111 A along a fixed direction, the permanent magnet generator  11 A still can generate electricity. Furthermore, understandably, when the number of the plurality of the rotor slots  1123 A and the number of the plurality of the stator slots  1114 A are greater than 64 and 72, respectively, the angle of the rotating movement or the swinging movement of the rotor body  1121 A relative to the stator body  1111 A which is required for the stator coils  1112 A to generate the electrical current is less than 22.5 degrees, which allows the permanent magnet generator  11 A to generate electricity when the rotor body  1121 A is driven by the waves to swing relative to the stator body  1111 A at a smaller angle back and forth. 
     However, the structures of the first driving component and the second driving component are not limited to the ones illustrated in the figures of the aforementioned embodiment. For example, please refer to  FIG. 7  to  FIG. 8 .  FIG. 7  is a schematic diagram of a wave energy conversion device  1 B according to a second embodiment of the present invention.  FIG. 8  is an exploded diagram of the wave energy conversion device  1 B according to the second embodiment of the present invention. As shown in  FIG. 7  to  FIG. 8 , in this embodiment, the wave energy conversion device  1 B includes a permanent magnet generator  11 B, a first driving component  12 B and a second driving component  13 B. The structure of the permanent magnet generator  11 B of this embodiment is similar to the one of the permanent magnet generator  11 A of the first embodiment. Detailed description is omitted herein for simplicity. Different from the first embodiment, in this embodiment, the first driving component  12 B is connected to a connecting shaft  1124 B of a rotor structure  112 B of the permanent magnet generator  11 B by a connecting frame  14 B. The wave energy conversion device  1 B utilizes a connection of the connecting frame  14 B and the connecting shaft  1124 B to achieve a coupling connection of the first driving component  12 B and the rotor structure  112 B and further utilizes the coupling connection of the first driving component  12 B and the rotor structure  112 B and a coupling connection of the second driving component  13 B and a stator structure  111 B to convert a wave movement into a rotating movement or a swinging movement of a rotor body of the rotor structure  112 B relative to a stator body of the stator structure  111 B by the first driving component  12 B and the second driving component  13 B, so as to achieve a purpose of electricity generation by the wave energy conversion. 
     Besides, please refer to  FIG. 9  to  FIG. 10 .  FIG. 9  is a schematic diagram of a dual-axial wave energy conversion device  1 C according to a third embodiment of the present invention.  FIG. 10  is an exploded diagram of the dual-axial wave energy conversion device  1 C according to the third embodiment of the present invention. As shown in  FIG. 9  to  FIG. 10 , the dual-axial wave energy conversion device  1 C includes a first permanent magnet generator  11 C, a second permanent magnet generator  12 C, a first driving component  13 C and a second driving component  14 C. Each of the first driving component  13 C and the second driving component  14 C can be a floating component. However, the present invention is not limited thereto. The internal structure of each of the first permanent magnet generator  11 C and the second permanent magnet generator  12 C is similar to the one of the permanent magnet generator  11 A of the first embodiment. Detailed description for the internal structures of the first permanent magnet generator  11 C and the second permanent magnet generator  12 C is omitted herein for simplicity, and related illustration can be referred to the first embodiment. Different from the first embodiment, in this embodiment, a second stator structure  121 C of the second permanent magnet generator  12 C is coupled to a first rotor structure  112 C of the first permanent magnet generator  11 C. The first driving component  13 C is coupled to a first stator structure  111 C of the first permanent magnet generator  11 C. The second driving component  14 C is coupled to a second rotor structure  122 C of the second permanent magnet generator  12 C. A swinging direction or a rotating direction of a second rotor body, which is not shown in the figures, of the second rotor structure  122 C of the second permanent magnet generator  12 C is different from a swinging direction or a rotating direction of a first rotor body, which is not shown in the figures, of the first rotor structure  112 C of the first permanent magnet generator  11 C. Preferably, a first central axis R 1 C of the first rotor body can be perpendicular to a second central axis R 2 C of the second rotor body, so that the swinging direction or the rotating direction of the second rotor body of the second rotor structure  122 C of the second permanent magnet generator  12 C can be different from the swinging direction or the rotating direction of the first rotor body of the first rotor structure  112 C of the first permanent magnet generator  11 C. Therefore, the first permanent magnet generator  11 C and the second permanent magnet generator  12 C can convert wave energy transmitted along different directions into electricity. 
     Specifically, only one end of a second connecting shaft  1221 C of the second rotor structure  122 C of the second permanent magnet generator  12 C protrudes out of a second shell  1211 C of the second stator structure  121 C, and the end of the second connecting shaft  1221 C protruding out of the second shell  1211 C is connected to the second driving component  14 C. The second shell  1211 C of the second stator structure  121 C is connected to a first connecting shaft  1121 C of the first rotor structure  112 C of the first permanent magnet generator  11 C by a connecting frame  15 C. A first shell  1111 C of the first stator structure  111 C of the first permanent magnet generator  11 C is connected to the first driving component  13 C. However, the present invention is not limited to this embodiment. In another embodiment, another end of the second connecting shaft away from the second driving component also can be configured to be protruding out of the second shell and coupled to the connecting frame, i.e., the connecting frame is not connected to the second shell. 
     In this embodiment, the dual-axial wave energy conversion device  1 C can convert the wave movements along different directions into a rotating movement or a swinging movement of the first rotor body of the first rotor structure  112 C relative to a first stator body of the first stator structure  111 C and a rotating movement or a swinging movement of the second rotor body of the second rotor structure  122 C relative to a second stator body of the second stator structure  121 C. Therefore, even if the wave direction is changed by wind, the dual-axial wave energy conversion device  1 C still can generate electricity stably, which improves reliability and stability of electricity generation. 
     Please refer to  FIG. 11  and  FIG. 12 .  FIG. 11  is a schematic diagram of a dual-axial wave energy conversion device  1 D according to a fourth embodiment of the present invention.  FIG. 12  is an exploded diagram of the dual-axial wave energy conversion device  1 D according to the fourth embodiment of the present invention. As shown in  FIG. 11  and  FIG. 12 , the dual-axial wave energy conversion device  1 D includes a first permanent magnet generator  11 D, a second permanent magnet generator  12 D, a first driving component  13 D and a second driving component  14 D. Each of the first driving component  13 D and the second driving component  14 D can be a floating component. However, the present invention is not limited thereto. The internal structure of each of the first permanent magnet generator  11 D and the second permanent magnet generator  12 D is similar to the one of the permanent magnet generator  11 A of the first embodiment. Detailed description for the internal structures of each of the first permanent magnet generator  11 D and the second permanent magnet generator  12 D is omitted herein for simplicity, and related illustration can be referred to the first embodiment. Different from the first embodiment, in this embodiment, a second stator structure  121 D of the second permanent magnet generator  12 D is coupled to a first stator structure  111 D of the first permanent magnet generator  11 D. The second driving component  14 D is coupled to a second rotor structure  122 D of the second permanent magnet generator  12 D. A swinging direction or a rotating direction of a second rotor body, which is not shown in the figures, of the second rotor structure  122 D of the second permanent magnet generator  12 D is different from a swinging direction or a rotating direction of a first rotor body, which is not shown in the figures, of the first rotor structure  112 D of the first permanent magnet generator  11 D. Preferably, a first central axis R 1 D of the first rotor body can be perpendicular to a second central axis R 2 D of the second rotor body, so that the swinging direction or the rotating direction of the second rotor body of the second rotor structure  122 D of the second permanent magnet generator  12 D can be different from the swinging direction or the rotating direction of the first rotor body of the first rotor structure  112 D of the first permanent magnet generator  11 D. Therefore, the first permanent magnet generator  11 D and the second permanent magnet generator  12 D can convert wave energy transmitted along different directions into electricity. 
     Specifically, two ends of a second connecting shaft  1221 D of the second rotor structure  122 D of the second permanent magnet generator  12 D protrude out of a second shell  1211 D of the second stator structure  121 D and are connected to the second driving component  14 D. The second shell  1211 D of the second stator structure  121 D is connected to a first shell  1111 D of the first stator structure  111 D of the first permanent magnet generator  11 D by a connecting frame  15 D. A first connecting shaft  1121 D of the first rotor structure  112 D is connected to the first driving component  13 D. 
     In this embodiment, the dual-axial wave energy conversion device  1 D can convert the wave movements along different directions into a rotating movement or a swinging movement of the first rotor body of the first rotor structure  112 D relative to a first stator body of the first stator structure  111 D and a rotating movement or a swinging movement of the second rotor body of the second rotor structure  122 D relative to a second stator body of the second stator structure  121 D. Therefore, even if the wave direction is changed by wind, the dual-axial wave energy conversion device  1 D still can generate electricity stably, which improves reliability and stability of electricity generation. 
     Please refer to  FIG. 13  and  FIG. 14 .  FIG. 13  and  FIG. 14  are schematic diagrams of a dual-axial wave energy conversion device  1 E in different states according to a fifth embodiment of the present invention. As shown in  FIG. 13  and  FIG. 14 , the dual-axial wave energy conversion device  1 E includes a first permanent magnet generator  11 E, a second permanent magnet generator  12 E, a first driving component  13 E, a second driving component  14 E and a connecting frame  15 E. Each of the first driving component  13 E and the second driving component  14 E can be a floating component. However, the present invention is not limited thereto. The structures of the first permanent magnet generator  11 E, the second permanent magnet generator  12 E, the first driving component  13 E, the second driving component  14 E and the connecting frame  15 E are similar to the ones of the fourth embodiment. Detailed description for the similar structures is omitted herein for simplicity. Different from the fourth embodiment, in this embodiment, the dual-axial wave energy conversion device  1 E further includes an extending and retracting assembly  16 E connected between the first permanent magnet generator  11 E and the first driving component  13 E and configured to move the first driving component  13 E for increasing or reducing a distance between the first driving component  13 E and the second driving component  14 E for adapting to different waves. 
     Specifically, the extending and retracting assembly  16 E includes a supporting frame  161 E and an extending and retracting rod  162 E. The supporting frame  161 E is connected to a first connecting shaft  1121 E of a first rotor structure  112 E of the first permanent magnet generator  11 E. Two ends of the extending and retracting rod  162 E are connected to the supporting frame  161 E and the first driving component  13 E, respectively. The extending and retracting rod  162  can drive the first driving component  13 E to move by hydraulic, electric or pneumatic means to increase or reduce the distance between the first driving component  13 E and the second driving component  14 E. 
     However, the present invention is not limited to this embodiment. In another embodiment, the extending and retracting assembly can be connected between the second permanent magnet generator and the second driving component to move the second driving component for increasing or reducing the distance between the first driving component and the second driving component. Alternatively, in another embodiment, the dual-axial wave energy conversion device can include two extending and retracting assemblies, wherein one of the two extending and retracting assemblies is connected between the first driving component and the first permanent magnet generator, and the other one of the two extending and retracting assemblies is connected between the second driving component and the second permanent magnet generator. 
     Please refer to  FIG. 15 .  FIG. 15  is a schematic diagram of a dual-axial wave energy conversion device  1 F according to a sixth embodiment of the present invention. As shown in  FIG. 15 , the dual-axial wave energy conversion device  1 F of this embodiment includes a first permanent magnet generator  11 F, a second permanent magnet generator  12 F, a first driving component  13 F, a second driving component  14 F and a connecting frame  15 F. Each of the first driving component  13 F and the second driving component  14 F can be a floating component. However, the present invention is not limited thereto. The structures of the first permanent magnet generator  11 F, the second permanent magnet generator  12 F, the first driving component  13 F, the second driving component  14 F and the connecting frame  15 F are similar to the ones of the third embodiment. Detailed description for the similar structures is omitted herein for simplicity. Different from the third embodiment, in this embodiment, the dual-axial wave energy conversion device  1 F further includes a extending and retracting assembly  16 F connected to the second permanent magnet generator  12 F and the second driving component  14 F and configured to move the second driving component  14 F for increasing or reducing a distance between the first driving component  13 F and the second driving component  14 F for adapting to different waves. 
     Specifically, the extending and retracting assembly  16 F includes an extending and retracting rod  161 F connected to a second connecting shaft  1221 F of the second permanent magnet generator  12 F and the second driving component  14 F. 
     Furthermore, the structure of the dual-axial wave energy conversion device is not limited to the aforementioned embodiments. For example, in another embodiment, when the first driving component is coupled to the first rotor structure, the first stator structure and the second driving component can be coupled to one of the second rotor structure and the second stator structure and the other one of the second rotor structure and the second stator structure, respectively. Alternatively, in another embodiment, when the first driving component is coupled to the first stator structure, the first rotor structure and the second driving component can be coupled to one of the second rotor structure and the second stator structure and the other one of the second rotor structure and the second stator structure, respectively. 
     In addition, the structures of the first driving component and the second driving component are not limited to the ones illustrated in the figures of the aforementioned embodiments. The first driving component and/or the second driving component of any of the aforementioned embodiments can be modified to be extendable and retractable according to practical demands for improving adaptation to different waves. For example, please refer to  FIG. 16 .  FIG. 16  is a diagram of a first driving component  13 G and a second driving component  14 G according to another embodiment of the present invention. As shown in  FIG. 16 , each of the first driving component  13 G and the second driving component  14 G of this embodiment can be a floating component including a first portion P 1  and a second portion P 2 , wherein the second portion P 2  can be driven by hydraulic, electric or pneumatic means to move relative to the first portion P 1  for increasing or reducing a total length of the floating component. 
     Besides, the wave energy conversion device or the dual-axial wave energy conversion device of any of the aforementioned embodiments can be further coupled to another driving component, another permanent magnet generator, or another wave energy conversion device or another dual-axial wave energy conversion device with identical or different structure, to form a multi-sectional wave energy conversion apparatus. 
     In contrast to the prior art, the wave energy conversion device of the present invention utilizes the coupling connection of the first driving component and the rotor structure and the coupling connection of the second driving component and the stator structure to convert the wave movement into the rotating movement or the swinging movement of the rotor body relative to the stator body by the first driving component and the second driving component. Furthermore, the ratio of the number of the plurality of rotor slots to the number of the plurality of stator slots can be 8:9, and the number of the plurality of the rotor slots and the number of the plurality of the stator slots can be at least equal to 64 and 72, respectively. Due to the aforementioned configuration, the wave energy conversion device only requires a low speed and a small angle of the rotating movement or the swinging movement of the rotor body relative to the stator body, for generating electricity. Therefore, even if amplitude of the wave movement is small, the wave energy conversion device can generate electricity stably, which improves reliability and stability of electricity generation. Besides, the wave energy conversion device has simple structure, which reduces maintenance cost. In addition, the dual-axial wave energy conversion of the present invention utilizes the coupling connection of the first driving component and the first permanent magnet generator, the coupling connection of the second driving component and the second permanent magnet generator and the coupling connection of the first permanent magnet generator and the second permanent magnet generator to convert wave movements along different directions into a rotating movement or a swinging movement of the first rotor body relative to the first stator body and a rotating movement or a swinging movement of the second rotor body relative to the second stator body by the first driving component and the second driving component. Moreover, the structure of each of the first permanent magnet generator and the second permanent magnet generator of the dual-axial wave energy conversion device is similar to the one of the permanent magnet generator of the wave energy conversion device. Due to the aforementioned configuration, the dual-axial wave energy conversion device only requires a low speed and a small angle of the rotating movement or the swinging movement of the first rotor body relative to the first stator body and a low speed and a small angle of the rotating movement or the swinging movement of the second rotor body relative to the second stator body but does not require a fixed wave direction, for generating electricity. Therefore, even if amplitude of the wave movement is small and the wave direction is changed by wind, the dual-axial wave energy conversion device still can generate electricity stably, which improves reliability and stability of electricity generation. Besides, the dual-axial wave energy conversion device has simple structure, which reduces maintenance cost. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.