Abstract:
An energy conversion system transfers energy between an energy source, or storage unit, and an electric device via a first port and a second port and at least one of receives and provides energy via a third port.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of application Ser. No. 13/484,679, filed May 31, 2012, which is a divisional of application Ser. No. 11/537,083, filed Sep. 29, 2006, the disclosures of which are hereby incorporated by reference in their entirety herein. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The invention relates to energy conversion systems for vehicles. 
     2. Background Discussion 
     Direct current to direct current (DC/DC) buck, boost, or bi-directional converters may transfer energy between an energy source, or storage unit, e.g., a high-voltage battery, via a first port at a first voltage and an electric device, e.g., motor drive, via a second port at a second voltage higher than the first voltage. 
     A vehicle system may require energy to be transferred between several energy storage units and electric devices at differing voltages. Several DC/DC converters may be necessary to facilitate such energy transfer. 
     An energy conversion system is desired that can facilitate the transfer of energy between one or more energy storage units and one or more electric devices at differing voltages. 
     SUMMARY 
     In at least one embodiment, the invention takes the form of an energy conversion system for a vehicle. The system includes an energy source, or storage unit, an electric device, and an energy conversion arrangement. The arrangement transfers energy between the energy storage unit and the electric device via a first port and a second port. The arrangement also at least one of receives and provides energy via a third port. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an energy conversion system in accordance with an embodiment of the invention. 
         FIG. 2  shows an energy conversion arrangement in accordance with an embodiment of the invention. 
         FIG. 3  shows an energy conversion arrangement in accordance with an embodiment of the invention. 
         FIG. 4  shows a transformer in accordance with an embodiment of the invention. 
         FIG. 5  shows a transformer in accordance with an embodiment of the invention. 
         FIG. 6  shows a transformer in accordance with an embodiment of the invention. 
         FIGS. 7 a -7 d    show circuits in accordance with embodiments of the invention. 
         FIG. 8  shows an energy conversion arrangement in accordance with an embodiment of the invention. 
         FIG. 9  shows an energy conversion arrangement in accordance with an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows energy conversion system  10  for vehicle  12 . System  10  includes energy sources, or storage units,  14 ,  15 , energy conversion arrangement  16 , and electric devices  18 ,  19 . Arrangement  16  is electrically connected with units  14 ,  15  and devices  18 ,  19 . Arrangement  16  may receive energy from or provide energy to units  14 ,  15 , as will be explained in detail below. Arrangement  16  may also receive energy from or provide energy to devices  18 ,  19 , as will be explained in detail below. 
       FIG. 2  shows an embodiment of arrangement  16 . In this embodiment, arrangement  16  receives energy from unit  14  and provides energy to device  18  and acts, inter alia, as a DC/DC boost converter. 
     Arrangement  16  includes capacitors  20 ,  22 , switch  24 , diode  26 , and transformer  28  as shown in  FIG. 2 . Switch  24  is an insulated gate bipolar transistor (IGBT). Switch  24 , however, may be implemented in any suitable fashion, such as with field effect transistors (FETs). Transformer  28  may be an isolated transformer or a non-isolated transformer, as will be explained in detail below. 
     Arrangement  16  also includes terminals  30 ,  31 ,  32 . Terminal  31  is common relative to terminal  30  and terminal  32 . Unit  14 , capacitor  20 , and transformer  28  are electrically connected with terminal  30 . Unit  14  and capacitor  20  are also electrically connected with terminal  31 . Terminal  30  and terminal  31  are a port. Device  18  is electrically connected with terminal  31  and terminal  32 . Terminal  31  and terminal  32  are a port. The voltage, Vy, at terminal  32  relative to terminal  31  is greater than the voltage, Vx, at terminal  30  relative to terminal  31 . Arrangement  16  further includes node  33 . 
     Arrangement  16  passes current between terminal  30  and terminal  32  in a manner typical of DC/DC boost converters through the selective opening and closing of switch  24 , e.g., pulse width modulation. When switch  24  is conducting, the current through transformer  28  increases thereby increasing the energy stored in transformer  28 . When switch  24  is not conducting, the energy stored in transformer  28  forces diode  26  to conduct thereby delivering current to terminal  32 . 
     Arrangement  16  also includes one or more terminals  36 , i.e.,  36   a - 36   n . Terminals  36   a - 36   n  are electrically connected to transformer  28 , as will be explained in detail below. Terminal  36   a  may be electrically connected with unit  15 . Terminal  36   b  may be electrically connected with device  19 . If transformer  28  is a non-isolated transformer, unit  15  and device  19  may share a common reference terminal, e.g., terminal  31 . Terminal  31  and any of terminals  36   a - 36   n  may be a port. If transformer  28  is an isolated transformer, unit  15  and device  19  may or may not share a common reference terminal. Preferably, unit  15  and device  19  would not share a common reference terminal if transformer  28  is an isolated transformer. Any two of terminals  36   a - 36   n  may be a port. 
       FIG. 3  shows an embodiment of arrangement  16 . In this embodiment, arrangement  16  receives energy from device  18  and provides energy to unit  14  and acts, inter alia, as a DC/DC buck converter. 
     Arrangement  16  includes capacitors  20 ,  22 , switch  24 , diode  26 , and transformer  28 . Switch  24  is an IGBT. Switch  24 , however, may be implemented in any suitable fashion, such as with FETs. Transformer  28  may be an isolated transformer or a non-isolated transformer as explained above. Arrangement  16  also includes terminals  30 ,  31 ,  32 . Terminal  31  is common relative to terminal  30  and terminal  32 . Unit  14 , capacitor  20 , and transformer  28  are electrically connected with terminal  30 . Unit  14  and capacitor  20  are also electrically connected with terminal  31 . Device  18  is electrically connected with terminal  31  and terminal  32 . The voltage, Vy, at terminal  32  relative to terminal  31  is greater than the voltage, Vx, at terminal  30  relative to terminal  31 . Arrangement  16  further includes node  33 . 
     Arrangement  16  passes current between terminal  30  and terminal  32  in a manner typical of DC/DC buck converters through the selective opening and closing of switch  24 , e.g., pulse width modulation. When switch  24  is conducting, current flows from terminal  32  to terminal  30 . When switch  24  is not conducting, current flows from terminal  31  to terminal  30 . 
     Arrangement  16  also includes one or more terminals  36 , i.e.,  36   a - 36   n . Terminals  36  are electrically connected to transformer  28  as will be explained in detail below. Terminal  36   a  may be electrically connected with unit  15 . Terminal  36   b  may be electrically connected with device  19 . 
       FIG. 4  shows an isolated version of transformer  28 . This isolated transformer  28  includes primary winding  38  and secondary winding  40 , both being wound around magnetic core  42 . The transformer  28  may have multiple mutually isolated secondary windings  40 . Terminals  36   a - 36   n  have voltages with no offset. The amplitude of the voltage difference between terminals  36   a  and  36   x  is less than the amplitude of the voltage difference between terminals  36   a  and  36   n . Current coming from any of terminals  36   a - 36   n  may be rectified in any suitable fashion, such as with a full-wave rectifier or half-wave rectifier, as will be explained in detail below. 
       FIG. 5  shows a non-isolated version of transformer  28 . This non-isolated transformer  28  includes primary winding  44  wound around magnetic core  46 . Terminals  36   a - 36   n  have voltages, with respect to terminal  31  or any other common reference terminal, with offset. Terminal  30  may be connected with any of terminals  36   a - 36   n . Node  33  may be connected with any of terminals  36   a - 36   n . Terminal  30  and node  33 , however, may not be connected to the same terminal. Current coming from any of terminals  36   a - 36   n  may be rectified in any suitable fashion, such as with a full-wave rectifier or half-wave rectifier, as will be explained in detail below. This non-isolated transformer  28  may also include isolated secondary windings. Therefore, it may have non-isolated as well as isolated outputs. 
       FIG. 6  shows an isolated version of transformer  28 . Switches  48 ,  50 ,  52 , and  54  may be selectively opened or closed. If switch  54  is closed and switches  48 ,  50 , and  52  are open, secondary winding  40  is isolated from primary winding  38 . It provides power to a load with galvanic isolation with respect to the primary side. If secondary winding  40  is not used, it can be incorporated with primary winding  38  to increase the power rating or inductance. For example, if switches  48 ,  50 , and  54  are closed and switch  52  is open, primary winding  38  and secondary winding  40  are connected in parallel, thus increasing the current rating of transformer  28 . If switches  50  and  52  are closed and switches  48  and  54  are open, primary winding  38  and secondary winding  40  are connected in series, thus increasing the inductance of transformer  28 . Switches  48 ,  50 ,  52 , and  54  may be implemented in any suitable fashion. In the embodiment of  FIG. 6 , switches  48 ,  50 ,  52 , and  54  are relays. 
       FIG. 7 a    shows rectifier circuit  56  that may be used with transformer  28 . Circuit  56  includes diodes  58 ,  60  electrically connected, as shown, along with output terminals  62 ,  64 . If the voltage at terminal  36  is greater than the voltage at terminal  62 , diode  58  will conduct. If the voltage at terminal  36  is less than the voltage at terminal  64 , diode  60  will conduct. 
       FIG. 7 b    shows rectifier circuit  66  that may be used in conjunction with transformer  28 . Circuit  66  includes diodes  68 ,  70 ,  72 , and  74  electrically connected as shown. Circuit  66  also includes terminals  76 ,  78 ,  80 , and  82 . Terminal  76  and terminal  82  are a port. Terminal  78  and terminal  80  are another port. The ports do not share a common reference terminal and they deliver two output voltages with different amplitudes. 
       FIG. 7 c    shows rectifier circuit  84  that may be used in conjunction with transformer  28 . Circuit  84  includes diodes  86 ,  88 ,  90 , and  92  electrically connected as shown. Circuit  84  also includes terminals  94 ,  96 , and  98 . Terminal  94  and terminal  98  are a port. Terminal  96  and terminal  98  are another port. The ports share common negative-side reference terminal  98 . The outputs of the ports are of the same polarity but may have different output voltage amplitudes. 
       FIG. 7 d    shows rectifier circuit  100  that may be used in conjunction with transformer  28 . Circuit  100  includes diodes  102 ,  104 ,  106 , and  108  electrically connected as shown. Circuit  100  also includes terminals  110 ,  114 , and  116 . Terminal  114  and terminal  110  are a port. Terminal  116  and terminal  110  are another port. The ports share common positive-side reference terminal  110 . The outputs of the ports are of the same polarity but may have different output voltage amplitudes. 
       FIG. 8  shows an embodiment of arrangement  16 . This embodiment includes capacitors  118 ,  120 , terminals  122 ,  123 ,  124 , node  126 , diodes  128 ,  130 , active switches  132 ,  134 , and non-isolated transformer  136 . In this configuration, arrangement  16  can act as either a buck or boost converter. If switch  132  is disabled, arrangement  16  acts, inter alia, as a boost converter. If switch  134  is disabled, arrangement  16  acts, inter alia, as a buck converter. The voltage at terminal  122  is less than the voltage at terminal  124  relative to terminal  123 . 
     Non-isolated transformer  136  includes terminals  138 , e.g.,  138   a - 138   j . Terminals  140 , e.g.,  140   a - 140   h , and terminals  142 , e.g.,  142   a - 142   h , are also shown. Other embodiments may have more or less terminals. The diodes may or may not be included. 
     If arrangement  16  acts as a buck converter, i.e., switch  134  is disabled, the voltage at terminals  142   g - 142   h  is less than the voltage at terminal  122 , the voltage at terminals  142   e - 142   f  is less than the voltage at terminal  122  but greater than zero, and the voltage at terminals  142   a - 142   d  is less than zero. Furthermore, the voltage at terminals  140   g - 140   h  is greater than the voltage at terminal  122 , the voltage at terminals  140   e - 140   f  is greater than the voltage at terminal  122  but less than the voltage at terminal  124 , and the voltage at terminals  140   a - 140   d  is greater than the voltage at terminal  124 . 
     In this configuration, arrangement  16  can receive energy from unit  15  or device  19  if unit  15  or device  19  are suitably electrically connected with any of terminals  142   e - 142   h . Arrangement  16  can provide energy to unit  15  or device  19  if unit  15  or device  19  are suitably electrically connected to any of terminals  140   a - 140   h  or  142   a - 142   d.    
     If arrangement  16  acts as a boost converter, i.e., switch  132  is disabled, the voltage at terminals  142   g - 142   h  is less than the voltage at terminal  122 , the voltage at terminals  142   e - 142   f  is less than the voltage at terminal  122  but greater than zero, and the voltage at terminals  142   a - 142   d  is less than zero. Furthermore, the voltage at terminals  140   g - 140   h  is greater than the voltage at terminal  122 , the voltage at terminals  140   e - 140   f  is greater than the voltage at terminal  122  but less than the voltage at terminal  124 , and the voltage at terminals  140   a - 140   d  is greater than the voltage at terminal  124 . 
     In this configuration, arrangement  16  can receive energy from unit  15  or device  19  if unit  15  or device  19  are suitably electrically connected with any of terminals  142   e - 142   h . Arrangement  16  can provide energy to unit  15  or device  19  if unit  15  or device  19  are suitably electrically connected to any of terminals  140   a - 140   h  or  142   a - 142   d.    
       FIG. 9  shows an embodiment of arrangement  16 . This embodiment includes capacitors  118 ,  120 , terminals  122 ,  123 ,  124 , node  126 , diodes  128 ,  130 , active switches  132 ,  134 , and isolated transformer  144 . In this configuration, arrangement  16  can act as either a buck or boost converter. If switch  132  is disabled, arrangement  16  acts, inter alia, as a boost converter. If switch  134  is disabled, arrangement  16  acts, inter alia, as a buck converter. The voltage at terminal  122  is less than the voltage at terminal  124  relative to terminal  123 . 
     Isolated transformer  144  includes terminals  146 , e.g.,  146   a - 146   j . Terminals  148 , e.g.,  148   a - 148   j , and terminals  150 , e.g.,  150   a - 150   j , are also shown. Other embodiments may have more or less terminals. The diodes may or may not be included. The diodes may also be shorted. 
     In this configuration, arrangement  16  can provide energy to unit  15  or device  19  if unit  15  or device  19  are suitably electrically connected to any of terminals  150   a - 150   j  or  148   a - 148   j.    
     While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.