Abstract:
A power module for medium and high-voltage frequency converter and a frequency converter comprising same. The power module has a three-phase alternating current input and a single-phase alternating current output, and comprises a circuit board ( 100 ), a rectifying module ( 120 ), a capacitor bank ( 130 ), and an inverting module ( 140 ), wherein the rectifying module, the capacitor bank and the inverting module are all mounted on the circuit board. The power module has a compact structure and is convenient to cool.

Description:
FIELD OF INVENTION 
       [0001]    The present application relates to a power module for medium and high-voltage frequency converter, and more specifically, relates to a power module for medium and high-voltage frequency converter with three-phase AC input and single-phase AC output. The present application also relates to a converter including the power module. 
       BACKGROUND OF INVENTION 
       [0002]    Power module is an integrated component or module capable of processing electricity, and it is integrated by different components and technology according to optimum electrical circuit structure and system structure. Multiple power modules can work together to constitute a power electronics system, so as to achieve systematic functions such as voltage transformation, energy storage and conversion, and impedance matching. For medium and high-voltage frequency converter, multiple power modules in a cabinet are usually connected in series to regulate power. In order to make the system structure compact, it is necessary to compact the structure of power module in the cabinet while optimizing cooling of the power module. 
       SUMMARY OF INVENTION 
       [0003]    The present application provides a power module for medium and high-voltage frequency converter, having a three-phase AC input and a single-phase AC output, characterized in that the power module includes a circuit board, a rectifying module, a capacitor bank, and an inverting module, wherein the rectifying module, the capacitor bank and the inverting module are all mounted on the circuit board. 
         [0004]    In one embodiment, at least part of capacitors in the capacitor bank are welded on the circuit board. 
         [0005]    In one embodiment, the power module further includes a control board mounted on the circuit board. 
         [0006]    In one embodiment, in use, capacitors in the capacitor bank stand on the circuit board. 
         [0007]    In one embodiment, the power module further includes a supporting structure for supporting the circuit board. 
         [0008]    In one embodiment, the power module further includes a housing with a recess provided at rear end thereof. 
         [0009]    In one embodiment, the housing is further provided with a positioner thereon. 
         [0010]    In one embodiment, the circuit board is further provided with a relay and a charging resistor thereon. 
         [0011]    In one embodiment, the power module further includes at least two fuses arranged in parallel with the circuit board and in parallel with each other. 
         [0012]    In one embodiment, in use, air flows through the rectifying module, the capacitor bank and the inverting module in order, to have them cooled. 
         [0013]    In one embodiment, the power module is further provided with an auxiliary computer. 
         [0014]    The above structure can make the power module more compact and reduce spurious emission interference, thus make the module more efficient. In addition, the structure is beneficial for cooling the rectifying module, the capacitor bank and the inverting module. Further, through this structure, the capacitor bank and the circuit board can be securely fastened, increasing the reliability of the power module. 
         [0015]    The present application further provides a converter, characterized by including the power module according to any one of above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  shows a schematic view of internal structure of a power module according to one embodiment of present application; 
           [0017]      FIG. 2  shows a front view of internal structure of a power module according to one embodiment of present application; 
           [0018]      FIG. 3  shows a schematic view of internal structure and its supporting structure, and partial housing of a power module according to one embodiment of present application; 
           [0019]      FIG. 4  shows a schematic view of internal structure of a power module according to another embodiment of present application; 
           [0020]      FIG. 5  shows a schematic view of external structure of a power module according to one embodiment of present application; and 
           [0021]      FIG. 6  shows an assembled view of a power module according to one embodiment of present application. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0022]    Detailed description of embodiments of present application is given below with reference to the drawings. 
         [0023]      FIG. 1  shows an internal structure of a power module having three-phase AC input and single-phase AC output. The power module includes a power assembly  100  and a housing  300  (see  FIG. 3  and  FIG. 5 ). The power assembly  100  includes a circuit board  110 , and a rectifying module  120 , a capacitor bank  130 , and an inverting module  140  mounted on the circuit board  110 , and a control board  150  inserted on the circuit board  110 . The rectifying module for example can be a six-pulse rectifier bridge, the inverting module for example can be an H-bridge IGBT, and the control board  150  can be provided with a main controller etc. to control the power module. In addition, the power module can be further provided with an auxiliary computer to provide redundancy and backup for the main controller. 
         [0024]    Mounting the rectifying module  120 , the capacitor bank  130 , and the inverting module  140  on the same circuit board  110  can make the structure more compact and reduce spurious emission interference, thus make the module more efficient. In addition, the structure is beneficial for cooling the rectifying module, the capacitor bank and the inverting module. As shown by arrow A in  FIG. 1 , the cooling air flows through the rectifying module, the capacitor bank and the inverting module in order, to effectively cool the module. Further, through this structure, the capacitor bank  130  can stand upright on the circuit board  110  instead of being cantilevered when the power module is installed into a converter, thus securely fastening the capacitor bank  130  and the circuit board  110  and increasing the reliability of the power module. 
         [0025]    The capacitor bank includes certain number of electrolytic capacitors, every three of which are connected in series to form a sub-group, and all sub-groups are connected in parallel. Preferably, all these capacitors have snap-in terminal and are welded onto the circuit board  110 . Comparing with traditional mounting using screws, it is more efficient and allows use of many small size capacitors to increase capacitor surface area and improve heat dissipation. Further, welded capacitor is hard to get loosed and thus module reliability can be increased. 
         [0026]    As shown in  FIG. 2 , the power module can also include a relay  160  and a charging resistor  165  mounted on the circuit board  110 , and the relay  160  is used to bypass the charging resistor  165 . The circuit board  110  can also be provided with an equalizing resistance (not shown) to balance the voltage between those capacitors connected in series. 
         [0027]      FIG. 3  and  FIG. 4  show the supporting structure  180  of the power assembly  100 . Since the rectifying module, the capacitor bank, and the inverting module are all mounted on the same circuit board  110 , the circuit board  110  is heavily loaded. In order to protect the circuit board  100  from being damaged, the present application proposes a supporting structure  180  to support the whole power assembly  100 . As shown in  FIG. 3  and  FIG. 4 , the supporting structure  180  is in U-shape, to support the circuit board  110  along its width direction and connect with housing  300  of the power module. Certainly, it should be understood that the supporting structure  180  can be in other form based on the supporting requirement and shall be not be limited to the drawings as shown. For example, the supporting structure  180  can support the circuit board  110  from its two sides in the way of cantilever. 
         [0028]      FIG. 4  shows a schematic view of a power module according to another embodiment of present application. As shown in  FIG. 4 , besides the above described structure, the power module further includes three fuses  210 ,  220  and  230  which are arranged in parallel with the circuit board and in parallel with each other. As shown, the three fuses are stacked in the direction perpendicular with the circuit board, and they are used for protecting the semiconductor components in the power module from being damaged. 
         [0029]      FIG. 5  schematically shows the external structure of a power module according to one embodiment of present application, while  FIG. 6  shows the assembled structure of two power modules. In order to compact the design of whole converter, distance between power modules needs to be reduced. However, the distance cannot be too short due to the requirement of clearance and creepage. Therefore, by restructuring the power module, the present application proposes a structure which can compactly arrange power modules while meeting the requirement of clearance and creepage. As shown in  FIG. 5  and  FIG. 6 , a recess  320  is provided at rear end of the housing  300 , so the creepage distance can be increased from S to S 1  with same arrangement of power modules. In addition, a positioner  330  can be provided on the housing  300  to accurately position the power module. The positioner  330  can engage with a corresponding positioner on cabinet when the power module is installed into the cabinet. The positioner  330  can be for example two protrusions while the corresponding positioners on the cabinet can be two grooves. The positioner  330  can also be a plate extending beyond the housing while the corresponding positioner on the cabinet can be a stopper for preventing the power module from vibrating. 
         [0030]    The present application also provides a converter including any one of the above described power module. 
         [0031]    Though the present invention has been described on the basis of some preferred embodiments, those skilled in the art should appreciate that those embodiments should by no way limit the scope of the present invention. Without departing from the spirit and concept of the present invention, any variations and modifications to the embodiments should be within the apprehension of those with ordinary knowledge and skills in the art, and therefore fall in the scope of the present invention which is defined by the accompanied claims.