Patent Document

CROSS-REFERENCE TO RELATED APPLICATION 
     This Application is a Section 371 National Stage Application of International Application No. PCT/KR2013/011996, filed Dec. 23, 2013 and published, not in English, as WO 2014/104676 A1 on Jul. 3, 2014. 
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to a power supply device for hybrid construction machinery and a method for the same, and more particularly, to a power supply device for hybrid construction machinery, which is capable of reducing engine loads and facilitating improvement of engine efficiency by excluding a starting motor used in general hybrid construction machinery and an alternator for charging a battery from hybrid construction machinery, such as a hybrid excavator or vehicle, which commonly uses an engine and an electric motor as a power source and includes an electric energy storage device, and a method for the same. 
     BACKGROUND OF THE DISCLOSURE 
     Recently, researches on hybrid construction machinery, which improves fuel efficiency by storing surplus power of an engine in a battery, and supplying power from the battery to the engine that does not have sufficient power so as to cope with a rapid increase in oil price, are being actively conducted. 
     A system, which uses the engine and an electric motor as a common power source as described above, and has an electrical energy storage device, refers to a hybrid system. For example, as the hybrid system, there is a hybrid system for heavy equipment, such as a hybrid vehicle, and an excavator. 
     In the meantime, a general excavator system performs an operation of driving, and turning or travelling or a boom, an arm, and a bucket, which are final loads, by using an engine as a power source through a medium, that is, hydraulic pressure. By contrast, a hybrid excavator system may improve total efficiency of the excavator system by additionally installing two motors and an electric storage device to a general excavator. Main components added to the hybrid excavator system include a motor, an electric storage device, an inverter, and a converter. Here, the electric storage device includes a battery and an ultra-capacitor (UC). 
       FIG. 1A  illustrates a hydraulic excavator system in the related art and  FIG. 1B  illustrates a hybrid excavator system in the related art. 
     The hybrid excavator system of  FIG. 1B  additionally uses an electric motor as a power source, in addition to an engine, so that the hybrid excavator system of  FIG. 1B  has the same basic configuration as that of the hybrid excavator system of  FIG. 1A  except for the addition of the configuration related to the driving of the electric motor and storage of electrical energy, that is, an engine auxiliary motor  103 , an engine auxiliary motor inverter  130 , a rotary motor  104 , a rotary motor inverter  140 , a DC link capacitor  150 , a UC  105  for storing electric energy, and a UC converter  160  for supplying electric energy to the UC  105 . 
     That is, both systems commonly and essentially requires mounting of a starting motor  10  for starting the engine  30  and an alternator  20  for charging a battery  101  for supplying electric energy to an excavator electric system  106 . 
     In the meantime, the hybrid excavator in the related art includes two methods, that is, a converter method ( FIG. 2A ) using a UC converter as a means for supplying electric energy to a UC for storing electric energy, and a converterless method ( FIG. 2B ) utilizing an initial charging unit instead of a converter. 
       FIG. 2A  illustrates the converter method and  FIG. 2B  illustrates the converterless methods. 
     First, a power supply device  100  of the hybrid excavator system according to the converter method of  FIG. 2A  includes a Switched-Mode Power Supply (SMPS)  110 , a logic control board  120 , an engine auxiliary motor inverter  130 , a rotary motor inverter  140 , a DC link capacitor  150 , and a UC converter  160  that is DC-DC converter. Here, the SMPS  110 , the logic control board  120 , the engine auxiliary motor inverter  130 , the rotary motor inverter  140 , and the UC converter  160  are connected to a control board battery  101 , an excavator electric device  102 , an engine auxiliary motor  103 , a rotary motor  104 , and a UC  105 , respectively. 
     The SMPS  110  is connected to the control board battery  101  to supply power to the logic control board  120 . 
     The logic control board  120  performs a function of sensing a voltage of the UC  105  and a voltage of the DC link capacitor  150  and controlling an initial driving logic. 
     The engine auxiliary motor inverter  130  performs a function of charging the DC link capacitor  150  by the engine auxiliary motor  103 . Here, the engine auxiliary motor  103  is directly connected to the engine  30 , and rotates at the same rpm as that of the engine  30  when the engine is driven. 
     When a power connector of the UC  105  is in an on state, the rotary motor inverter  140  performs a function of driving the rotary motor  104  according to a charged voltage. Here, the rotary motor  104  generates power necessary for a rotary operation of an excavator. 
     The DC link capacitor  150  charges a DC voltage converted by the engine auxiliary motor inverter  130 . The DC link capacitor  150  is connected to the UC converter  160 . 
     The UC converter  160  performs a function of charging the UC  105  by using electric energy stored in the DC link capacitor  150 . The UC converter  160  is connected between the DC link capacitor  150  and the UC  105 . Here, the UC  105  is charged with the voltage converted by the UC  105 . 
     The power converting device  100  including the DC-DC converter including the aforementioned configuration includes an inverter (for example, the engine auxiliary motor inverter  130  and the rotary motor inverter  140 ) driving a motor and a converter (for example, the UC converter  160 ) driving the UC. Here, the UC converter  160  accompanies an operation loss during a process of converting a voltage of a DC link to be charged in the UC  105 . 
     However, the UC converter  160  exists, so that there occurs a problem in that an operation loss is generated during the process of converting the voltage of the DC link to be charged in the UC  105 , a size of the power converting device  100  is increased, and excessive cost is generated, and in order to solve the problem, a converterless power conversion device, in which the UC converter  160  is omitted, as illustrated in  FIG. 2B  has been suggested. 
     Referring to  FIG. 2B , the converterless power conversion device has the same configuration as that of the converter method of  FIG. 2A , but is different from the converter method of  FIG. 2A  in that the UC converter  160  is omitted, but an initial charging unit  260  is provided between a DC link capacitor  250  and a UC  105  to charge the UC  105 . Further, a small capacity relay (SR 1  and SR 2 )  270  for initial charging and a large capacity connector (MC 1  and MC 2 )  280  for conducting a high current are provided in order to make a voltage of the UC  105  correspond to a voltage of the DC link capacitor  250 , so that the UC  105  makes a voltage of the UC  105  correspond to a voltage of the DC link capacitor  250  according to the operations of the small capacity relay (SR 1  and SR 2 )  270  for initial charging and the large capacity connector (MC 1  and MC 2 )  280  for conducting a high current controlled by an initial charging controller  220 . The converterless method solves the problem (cost, size, and the like) caused by the existence of the converter. 
     However, both the converter method of  FIG. 2A  and the converterless method of  FIG. 2B  commonly have a problem in that it is necessary to mount a starting motor for starting an engine and an alternator for charging a battery (see  FIG. 1B ). That is, there are problems in that the starting motor is high-priced, charging/discharging of the battery is repeated through the alternator to cause energy loss, a high current is output to the battery during starting, so that a lifespan of the battery is decreased, and engine efficiency deteriorates due to existence of the alternator, so that it is necessary to solve the problems. 
     The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. 
     SUMMARY 
     The summary and the abstract are provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. The summary and the abstract are not intended to identify key features or essential features of the claimed subject matter. 
     An embodiment of the present disclosure is conceived to solve the aforementioned problems, and an object of an embodiment of the present disclosure provides a power supply device for hybrid construction machinery capable of efficiently supplying power while a starting motor for starting an engine and an alternator for charging a battery are removed in hybrid construction machinery, and a method for the same. 
     In order to achieve the above object, a power supply device for hybrid construction machinery and a method for the same according to the present disclosure facilitate cost reduction and improve engine operation efficiency by removing a starting motor for starting an engine and an alternator for charging a battery, and facilitate an energy reduction effect by enabling electric energy to be supplied to an electric system without a process of charging/discharging the battery. 
     That is, the starting motor, which has been used to start the engine is removed, and instead, the engine is started by using an engine auxiliary motor. Further, a power conversion device (DC/DC converter) directly connected to a first capacitor means (DC link capacitor) storing energy generated by the engine auxiliary motor is provided, so that the battery is charged without the alternator and the power conversion device (DC/DC converter), instead of the battery, supplies energy to the electric system. 
     More particularly, an exemplary embodiment of the present disclosure provides a power supply device for hybrid construction machinery including an engine, a load motor, a battery, and an electric system, including: an engine auxiliary motor configured to start the engine when the hybrid construction machinery starts; a first capacitor means positioned between a first inverter connected to the engine auxiliary motor and a second inverter connected to the load motor, and accumulate generated electric energy; a second capacitor means configured to supply electric energy to the engine auxiliary motor through the first capacitor means when the hybrid construction machinery starts; a power conversion means positioned between a converter connected to the second capacitor means and the battery, and connected to the first capacitor means and the electric system to convert power; and a controller configured to charge the second capacitor means by using electric energy of the battery when a voltage of the second capacitor means is smaller than a reference voltage necessary for initially starting the engine when the hybrid construction machinery starts, and supply the electric energy accumulated in the first capacitor means to the electric system when the hybrid construction machinery is normally operated. 
     Another exemplary embodiment of the present disclosure provides a power supply method for hybrid construction machinery, including: checking a voltage of a second capacitor means when the hybrid construction machinery starts; accumulating electric energy in the second capacitor means by using electric energy of a battery when a voltage of the second capacitor means is smaller than a reference voltage necessary for initially starting the engine when the hybrid construction machinery starts; supplying electric energy to an engine auxiliary motor from the second capacitor means and starting an engine when the voltage of the second capacitor means is equal to or larger than a reference voltage necessary for initially starting the engine; and performing a normal operation of supplying electric energy accumulated in a first capacitor means to an electric system when the hybrid construction machinery normally operates. 
     The power supply device for hybrid construction machinery and the method for the same according to the present disclosure facilitate cost reduction and improve engine operation efficiency by removing a starting motor for starting an engine and an alternator for charging a battery, and facilitate an energy reduction effect by enabling electric energy to be supplied to an electric system without a process of charging/discharging the battery. 
     That is, the starting motor, which has been used for start the engine is removed, and instead, the engine is started by using an engine auxiliary motor. Further, a power conversion device (DC/DC converter) directly connected to a first capacitor means (DC link capacitor) storing energy generated by the engine auxiliary motor is provided, so that the battery is charged without the alternator and the power conversion device (DC/DC converter), instead of the battery, supplies energy to the electric system. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a configuration diagram of a hydraulic excavator system in the related art. 
         FIG. 1B  is a configuration diagram of a hybrid excavator system in the related art. 
         FIG. 2A  is a detailed diagram of a hybrid excavator system according to a converter method in the related art. 
         FIG. 2B  is a detailed diagram of a hybrid excavator system according to a converterless method in the related art. 
         FIG. 3  is a conceptual diagram of a power supply device for hybrid construction machinery according to the present disclosure. 
         FIG. 4A  is a detailed diagram of a hybrid excavator system according to a converter method according to the present disclosure. 
         FIG. 4B  is a detailed diagram of a hybrid excavator system according to a converterless method according to the present disclosure. 
         FIG. 5  is a flowchart for describing a power supply method by the power supply device for hybrid construction machinery according to the present disclosure. 
         FIGS. 6 and 7  are diagrams for describing an operation state for each operation mode of the device according to the present disclosure. 
     
    
    
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Description of Main Reference Numerals of the Drawings 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                  10: Starting motor 
                  30: Engine 
               
               
                   
                  20: Alternator 
                 101: Battery 
               
               
                   
                 106: Electric system 
                 103: Engine auxiliary motor 
               
               
                   
                 280: Controller 
                 130: Engine auxiliary motor inverter 
               
               
                   
                 150: DC link 
                 140: Rotary motor inverter 
               
               
                   
                 104: Rotary motor 
                 160: UC converter 
               
               
                   
                 105: Ultra capacitor 
                 290: DC/DC converter 
               
               
                   
                 291: Switching means 
                 292: Diode 
               
               
                   
                   
               
             
          
         
       
     
     DETAILED DESCRIPTION 
     Hereinafter, an exemplary embodiment of the present disclosure will be described in detail with reference to the accompanying drawing. A configuration of the present disclosure and an operation and an effect according to the configuration of the present disclosure will be clearly understood by the detailed description below. In the following description, the same elements will be designated by the same reference numerals although the elements are illustrated in different drawings, and a detailed explanation of known related constitutions may be omitted so as to avoid unnecessarily obscuring the subject matter of the present disclosure. 
       FIG. 3  is a conceptual diagram of a power supply device for hybrid construction machinery according to the present disclosure. The power supply device of  FIG. 3  is different from the power supply device for hybrid construction machinery in the related art of  FIG. 1B  in that the existing starting motor  10  and alternator  20  are removed. That is, the starting motor  10  used for starting an engine is removed, and instead, the engine starts by using an engine auxiliary motor  103 . 
     Further, a first charge storing means (DC link capacitor)  150  storing energy generated by the engine auxiliary motor  103  is directly connected to a power conversion means (DC/DC converter)  290 . The power conversion means (DC/DC converter)  290  performs charging of the battery  101  instead of the alternator, and supplies energy to an electric system  106 , instead of the battery  101 . 
     Further, the switching means  291  makes the battery  101  and a second capacitor means  105  be electrically conducted only when a voltage of the second capacitor means (UC)  105  is smaller than a reference voltage necessary for initially starting the engine when the hybrid construction machinery starts, so that the power supply device for hybrid construction machinery charges the second capacitor means  105  by the battery  101 . 
     Further, the power supply device for hybrid construction machinery may also include a current control means (diode)  292 , and when the power conversion means (DC/DC converter)  290  has a defect, the current control means  292  makes the battery  101  instead of the power conversion means (DC/DC converter)  290  supply electric energy to the electric system  106 . 
     Hereinafter, an exemplary embodiment of the present disclosure will be described in detail with reference to  FIGS. 4A and 4B . Detailed descriptions of the same contents as those of the related art are omitted, and different matters will be mainly described. 
       FIG. 4A  illustrates an exemplary embodiment of the present disclosure for a converter method, and  FIG. 4B  illustrates an exemplary embodiment of the present disclosure for a converterless method. 
     The converter method of  FIG. 4A  is different from the converter method in the related art illustrated in  FIG. 2A  in that the existing starting motor  10  and alternator  20  are omitted. 
     That is, the starting motor  10  used for starting the engine is removed, and instead, the engine starts by using the engine auxiliary motor  103 . 
     Further, the converter method of  FIG. 4A  is different from an existing converter method in that the power conversion means (DC/DC converter)  290  is provided. The power conversion means (DC/DC converter)  290  is directly connected to the first capacitor means (DC link capacitor)  150  storing energy generated by the engine auxiliary motor  103 . The power conversion means (DC/DC converter)  290  performs charging of the battery  101  instead of the alternator, and supplies energy to the electric system  106 , instead of the battery  101 . 
     Further, the switching means  291  makes the battery  101  and the second capacitor means (UC)  105  be electrically conducted only when a voltage of the second capacitor means (UC)  105  is smaller than a reference voltage necessary for initially starting the engine when the hybrid construction machinery starts, so that the second capacitor means (UC)  105  is charged by the battery  101 . 
     In the meantime, when the voltage of the second capacitor means (UC)  105  is equal to or larger than the reference voltage necessary for initially starting the engine, the switching means  291  is off, and instead, the second capacitor means  105  supplies electric energy to the engine auxiliary motor  103  to start the engine. 
     The aforementioned control is performed by a controller  280 . That is, when the voltage of the second capacitor means (UC)  105  is smaller than the reference voltage necessary for initially starting the engine when the hybrid construction machinery starts, the controller  280  controls the battery  101  to supply charging energy to the second capacitor means  105 , and when the voltage of the second capacitor means  105  is equal to or larger than the reference voltage necessary for initially starting the engine, the controller controls the second capacitor means  105  to supply electric energy to the engine auxiliary motor  103  to start the engine  30 . 
     The converterless method of  FIG. 4B  is different from the converterless method in the related art illustrated in  FIG. 2B  in that the existing starting motor  10  and alternator  20  are omitted. 
     The power conversion means (DC/DC converter)  290  is directly connected to the first capacitor means (DC link capacitor)  150  storing energy generated by the engine auxiliary motor  103 . The power conversion means (DC/DC converter)  290  performs charging of the battery  101  instead of the alternator, and supplies energy to the electric system  106 , instead of the battery  101 , which is similar to the converter method of  FIG. 4A . 
     Further, the switching means  291  makes the battery  101  and the second capacitor means (UC)  105  be electrically conducted only when a voltage of the second capacitor means (UC)  105  is smaller than a reference voltage necessary for initially starting the engine when the hybrid construction machinery starts, so that the second capacitor means (UC)  105  is charged by the battery  101 . 
     In the meantime, in the converterless method of  FIG. 4B , a current control means (diode)  292  may be further provided, differently from the converter method of  FIG. 4A . When the power conversion means (DC/DC converter)  290  has a defect, the current control means  292  makes the battery  101  supply electric energy to the electric system  106 , instead of the power conversion means (DC/DC converter)  290 . 
     The current control means  292  makes a voltage of the UC  105  correspond to a voltage of the DC link capacitor  250  according to an operation of a large capacitor contactor (MC)  280 - 1  for high current conduction. 
     The aforementioned control is performed by a controller  280 . That is, when the voltage of the second capacitor means (UC)  105  is smaller than the reference voltage necessary for initially starting the engine when the hybrid construction machinery starts, the controller  280  controls the battery  101  to supply charging energy to the second capacitor means  105 , and when the voltage of the second capacitor means  105  is equal to or larger than the reference voltage necessary for initially starting the engine, the controller controls the second capacitor means  105  to supply electric energy to the engine auxiliary motor  103  to start the engine  30 . 
       FIG. 5  is a flowchart for describing a power supply method by the power supply device for hybrid construction machinery according to the present disclosure. 
     When a driver initially turns a key to an on-position (S 10 ), the controller  280  checks a charging state of the second capacitor means (UC)  105  (S 20 ). 
     When a voltage of the UC  105  is equal to or larger than a reference voltage that is a minimum voltage necessary for initially starting the engine as a result of the check in operation S 20 , and energy of the UC  105  is sufficient to start the engine  30 , the controller  280  immediately enters to an engine starting mode and starts the engine  30  by using power of the UC  105  (S 40 ). 
     By contrast, when the voltage of the UC  105  is smaller than the reference voltage that is a minimum voltage necessary for initially starting the engine as the result of the check in operation S 20 , the controller  280  charges the UC  105  by using energy of the battery  101  (S 30 ), and then performs operation S 20  of checking the charging state of the UC  105  again. Then, when the voltage of the UC  105  reaches the reference voltage, the controller  280  drives in the engine starting mode (S 40 ). 
     In the meantime, when the engine  30  is started, the controller  280  supplies energy stored in the DC link capacitor  150  and  250  to the electric system  106  by using the DC/DC converter  290  as necessary power having of +24 V (S 50 ), and normally operates an excavator (S 60 ). 
       FIGS. 6 and 7  are diagrams for describing an operation state for each operation mode of the device according to the present disclosure. As described above, the power supply device according to the present disclosure includes a total of five operation modes including a UC charging mode ( FIGS. 6A and 7A ), an engine starting mode ( FIG. 6B ), a normal operation mode ( FIGS. 6C and 7B ), a battery charging mode ( FIG. 7C ), and a defect mode ( FIG. 7D ). 
     The UC charging mode will be described with reference to  FIGS. 6A and 7A . 
       FIGS. 6A and 7A  illustrate the UC charging mode, and when the UC is discharged during an initial start, so that the voltage of the UC is smaller than the reference voltage that is the minimum voltage necessary for starting an engine, the switching means  291  is on, and the UC is charged via the UC converter through the DC/DC converter  290  and the DC link  150  by using energy of the battery  101 . 
     The engine starting mode will be described with reference to  FIG. 6B . 
       FIG. 6B  illustrates the engine starting mode, and when the voltage of the UC is equal to or larger than the reference voltage, power is supplied to the inverter and the power generator through the UC converter and the DC link by using energy of the UC in order to start the engine, and the engine  30  is rotated through the supplied power to start the engine. 
     The normal operation mode will be described with reference to  FIGS. 6C and 7B . 
       FIGS. 6C and 7B  illustrate the normal operation mode after the engine starts. In the normal operation mode, the switching means  291  is off, and energy of the DC link  150  is converted into the necessary voltage (+24 V) via the DC/DC converter  290  and then necessary power is generated and supplied to the electric system  106 . 
     The battery charging mode will be described with reference to  FIG. 7C . 
       FIG. 7C  illustrates the battery charging mode, and the switching means  291  is turned on, energy stored in the DC link capacitor  150  is converted into necessary voltage (+24 V) via the DC/DC converter  290 , and then the battery  101  is charged with the necessary voltage (+24 V). 
     The defect mode will be described with reference to  FIG. 7D . 
       FIG. 7D  illustrates a defect mode, and a case where the DC/DC converter  290  has a defect. In this case, energy of the battery  101  is automatically supplied to the electric system  106  through the current control means  292 , instead of the DC/DC converter  290 . 
     From the foregoing, it will be appreciated that the exemplary embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made by those skilled in the art without departing from the scope and spirit of the present disclosure. The exemplary embodiments disclosed in the specification of the present disclosure do not limit the present disclosure. The scope of the present disclosure shall be construed on the basis of the following claims in such a manner that all of the technical ideas included within the scope equivalent to the claims belong to the present disclosure.

Technology Category: 7