referring to fig1 as described above , the power conversion system 10 of evs , fuel cell vehicles , and hevs typically includes a separate , discrete tim assembly 12 and dc / dc converter assembly 14 . the tim 12 inverts the high - voltage dc bus voltage to an ac voltage suitable for powering the motor 16 , such as a 3 - phase ac voltage . this power is inverted for driving and controlling the motor 16 , i . e ., for generating torque . the motor 16 , in combination with the transaxle , converts the electrical energy into mechanical energy which turns the wheels of the vehicle . the dc / dc converter 14 uses pwm to step the voltage associated with the vehicle &# 39 ; s high - voltage energy source 18 , such as a battery , fuel cell , ultracapacitor , flywheel , or superconducting energy storage device down to that which the alternator of an ice - powered vehicle would typically generate ( 13 . 5 - 14v ). the dc / dc converter 14 , which may be unidirectional or bi - directional , may be used to charge an auxiliary energy source 20 such as a 12v auxiliary battery , which is typically separated from the high - voltage energy source 18 . the dc / dc converter 14 may also be used to transfer power from the auxiliary energy source 20 to the high - voltage energy source 18 to , for example , start the vehicle . in general , the dc / dc converter 14 is operable for matching a plurality of voltages . the tim 12 and the dc / dc converter 14 typically comprise separate , discrete assemblies , including a 3 - phase assembly for the tim 12 and an h - bridge assembly for the dc / dc converter 14 . the tim 12 and the dc / dc converter 14 may also utilize separate , discrete high - voltage dc bus capacitors 22 and dc bus bars 24 . in this configuration , high - voltage cables must be utilized to connect the tim 12 and the dc / dc converter 14 . separate , discrete thermal management systems must be utilized to cool the tim 12 and the dc / dc 14 converter . the result is a complex , bulky , costly configuration . referring to fig2 in one embodiment , a system 30 including an integrated tim 12 ( fig1 ) and dc / dc converter 14 ( fig1 ) includes two integrated assemblies : a high - voltage assembly 32 , including the tim 12 and the high - voltage stage of the dc / dc converter 14 , and a low - voltage assembly 34 , including the low - voltage stage of the dc / dc converter 14 and a filter . the high - voltage assembly 32 is operatively connected to the low - voltage assembly 34 by a high - frequency transformer 36 . specifically , the method may include removing the high - voltage power transistors from the dc / dc converter 14 and integrating them with the tim &# 39 ; s transistor module . this configuration allows the tim 12 and the dc / dc converter 14 to share a high - voltage dc bus capacitor 38 and to utilize a simplified dc bus bar 40 . the integrated system 30 also includes the motor 16 , the high - voltage energy source 18 , and the auxiliary energy source 20 , while the high - voltage energy source 18 will typically take the form of a battery or fuel cell stack and the auxiliary energy source 20 will typically take the form of a battery , these energy sources may take the form of any or a combination of batteries , fuel cell stacks , ultracapacitors , flywheels , and / or superconducting magnetic storage devices . in this configuration , high - voltage cables utilized to connect the tim 12 and the dc / dc converter 14 may be eliminated and a common thermal management system may be utilized to cool the high - voltage power stage of the tim 12 and the dc / dc converter 14 . the result is a simple , compact , inexpensive configuration . referring to fig3 in another embodiment , a tim 12 , such as a 55 kw tim inverter , may be integrated with a dc / dc converter 14 , such as a 3 kw boost 2 kw buck bi - directional dc / dc converter . the integrated system 50 includes a high - voltage bridge module 52 for the tim 12 and the dc / dc converter 14 and a low - voltage bridge module 54 for the dc / dc converter 14 . the high - voltage bridge module 52 is operatively connected to the low - voltage bridge module 54 by a high - frequency transformer 36 . the integrated system 50 may also include the motor 16 , a 250 - 420v high - voltage energy source 18 , and the auxiliary energy source 20 . the integrated system 50 may further include a plurality of switches 56 , such as insulated gate bipolar transistors ( igbts ) 58 or mosfets . in this configuration , high - voltage cables utilized to connect the tim 12 and the dc / dc converter 14 may be eliminated and a common thermal management system may be utilized to cool the high - voltage power stage of the tim 12 and the dc / dc converter 14 . again , the result is a simple , compact , inexpensive configuration . referring to fig4 in a further embodiment , a tim 12 , such as a 55 kw tim inverter , may be integrated with a dc / dc converter 14 , such as a 2 kw buck converter for 12v loads . the integrated system 60 includes a high - voltage bridge module 52 for the tim 12 and the dc / dc converter 14 and a low - voltage rectifier 62 for the dc / dc converter 14 . the high - voltage bridge module 52 is operatively connected to the low - voltage rectifier 62 by a high - frequency transformer 36 . the integrated system 60 may also include the motor 16 , the 250 - 420v high - voltage energy source 18 , and the 12v auxiliary energy source 20 . the integrated system 60 may further include a plurality of switches 56 such as igbts 58 or mosfets . in this configuration , high - voltage cables utilized to connect the tim 12 and the dc / dc converter 14 may be eliminated and a common thermal management system may be utilized to cool the tim 12 and the dc / dc converter 14 . again , the result is a simple , compact , inexpensive configuration . referring to fig5 in a further embodiment , a tim 12 , such as a 55 kw tim inverter , may be integrated with a dc / dc converter 14 , such as a 45 - 55 kw bi - directional dc / dc converter . the integrated system 70 includes a high - voltage bridge module 52 for the tim 12 and the dc / dc converter 14 . the integrated system 70 may also include the motor 16 , the 250 - 420v high - voltage energy source 18 , and a 150 - 190v auxiliary energy source 20 . the integrated system 70 may further include a plurality of igbts 58 or mosfets . in this configuration , high - voltage cables utilized to connect the tim 12 and the dc / dc converter 14 may be eliminated and a common thermal management system may be utilized to cool the tim 12 and the dc / dc converter 14 . again , the result is a simple , compact , inexpensive configuration . all of the above u . s . patents , u . s . patent application publications , u . s . patent applications , foreign patents , foreign patent applications and non - patent publications referred to in this specification and / or listed in the application data sheet , including , but not limited to u . s . serial no . 60 / 319 , 116 filed feb . 20 , 2002 , are incorporated herein by reference , in their entirety . from the foregoing it will be appreciated that , although specific embodiments of the invention have been described herein for purposes of illustration , various modifications may be made without deviating from the spirit and scope of the invention . accordingly , the invention is not limited except as by the appended claims .