Abstract:
The invention relates to electrical power conversion and more specifically to a high power direct current-to-direct current (DC-DC) power converter. The DC-DC converter includes a plurality of input ports for receiving a plurality of inputs, each having current, voltage, and power, which can be selectively configured by a user. The DC-DC converter further includes a plurality of output channels for outputting current, voltage, and power, which may be selectively configured by a user. By allowing a user to configure both the inputs and outputs, the DC-DC converter may be utilized with wide variation of power conversion applications.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the priority benefit of U.S. provisional patent application Ser. No. 60/943,860, filed Jun. 14, 2007. The 60/943,860 provisional application is incorporated herein by reference, in its entirety, for all purposes. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention pertains generally to the field of direct current-to-direct current (or “DC-DC”) converter circuits, and more particularly to a DC-DC converter that is reconfigurable to accept input electrical power at plural different DC voltages, and reconfigurable to produce output electrical power at plural different DC voltages. 
       BACKGROUND INFORMATION 
       [0003]    A DC-DC converter receives as an input DC electrical power at a nominal input voltage and provides as an output DC electrical power at an output voltage that is different from, and typically higher than, the nominal input voltage. 
         [0004]    Conventionally, a given converter is designed for manufacture so as to accept a predetermined input voltage and will operate correctly only so long as the input voltage remains substantially at that predetermined value. If DC-DC conversion of a new, different input voltage is required, a different converter suitable to the new input voltage must be obtained, either purchased on the market or designed and manufactured from scratch. 
         [0005]    Likewise, if it is desired to change the output voltage of a given DC-DC converter, conventional converters do not function this way readily. Nor has the combination of both a changeable input voltage and a changeable output voltage been conventionally available in a DC-DC converter. 
         [0006]    What is needed is a DC-DC converter that is automatically reconfigurable to accept input electrical power at plural different DC voltages, and to produce output electrical power at plural, selectable different DC voltages. 
       SUMMARY OF THE INVENTION 
       [0007]    According to one embodiment of the present invention, a multi-output DC-DC converter has the ability for each of the outputs to configure respective input parameters, such as maximum input power and maximum and minimum input voltage ranges and the ability for each of the outputs to configure output parameters, such as output voltage, output current, and output power. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0008]    Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing. 
           [0009]    The FIGURE shows a schematic diagram of a DC-DC converter having multiple input voltages and multiple output voltages. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0010]    Referring to  FIG. 1 , wherein like numerals indicate corresponding parts throughout the several views, a direct current-to-direct current (DC-DC) power converter  20  is generally shown. The DC-DC power converter  20  includes an analog-to-digital (A-D) converter  22 , a processor module  24 , and a pulse width modulation (PWM) module  58 . The A-D converter  22  receives a plurality of analog power signals and analog current signals and electronically converts them into a plurality of digital power signals and digital current signals. The A-D converter  22  includes a plurality of first channel ports  32 ,  34 ,  36 ,  38 ,  40 , a plurality of second channel ports  42 ,  44 ,  46 ,  48 ,  50 , and a plurality of third channel ports  52 ,  54 ,  56 . Additionally, the A-D converter  22  includes an FET temperature port  26  for receiving a field effect transistor (FET) temperature signal, an ambient temperature port  28  for receiving an ambient temperature signal and a fuel cell voltage port  30  for receiving a fuel cell input voltage signal from a fuel cell (not shown). Although the FIGURE illustrates a fuel cell input voltage port for receiving a fuel cell input voltage, other DC voltage sources may be used including, but not limited to, fuel cells, batteries, flywheels, solar energy, ultra-capacitors, electric generator, etc. 
         [0011]    The plurality of first channel  32 ,  34 ,  36 ,  38 ,  40  includes a first channel low input current port  32  for receiving an analog first channel low input current signal and a first channel high input current port  34  for receiving an analog first channel high input current signal. A first channel low output current port  36  receives an analog first channel low output current signal and a first channel high output current port  38  receives an analog first channel high output current signal. A first channel output power port  40  is included for receiving a first channel output power signal, which may be utilized in a feedback control system to monitor and regulate the first channel output power, as discussed further below. 
         [0012]    The plurality of second channel ports  42 ,  44 ,  46 ,  48 ,  50  includes a second channel low input current port  42  for receiving an analog second channel low input current signal and a second channel high input current port  44  for receiving an analog second channel high input current signal. A second channel low output current port  46  receives an analog second channel low output current signal and a second channel high output current port  48  receives an analog second channel high output current signal. A second channel output power port  50  is included for receiving a second channel output power signal, which may be used utilized in a similar feedback manner as that of the first channel output power signal. 
         [0013]    The plurality of third channel ports  52 ,  54 ,  56  includes a third channel input current port  52  for receiving an analog third channel input current signal and a third channel output current port  54  for receiving an analog third channel output current signal. A third channel output power port  56  is included for receiving a third channel output power signal, which may be used in a similar feedback manner as that of the first and second channel output power signals. 
         [0014]    The processor module  24  is in electrical communication with the A-D converter  22  for receiving the digital power and digital current signals. The processor module  24  may output a plurality of electrical signals including a first channel select signal, a second channel select signal, a third channel select signal and a PWM frequency signal. The digital signals electrically may control various electrical modules  22 ,  58 ,  60 ,  62 ,  64 ,  66  included in the DC-DC power converter  20 , as discussed in greater detail below. Additionally, a crystal oscillator  68  is in communication with the processor module  24  for operating the processor module  24  at a predetermined frequency. 
         [0015]    The PWM module  58  is in communication with the processor module  24  and is responsive to the PWM frequency in order to output a PWM power signal. The processor module  24  generates the PWM frequency signal such that power level of the PWM power signal is substantially equal to the power level of the remotely connected fuel cell. Accordingly, the input voltage delivered to the DC-DC power converter  20  by the fuel cell (or other electrical power source) is substantially equal to the power level output by the PWM module  58 . 
         [0016]    The DC-DC converter  20  further includes a first channel field effect transistor (FET)  70  and second channel FET  72  and a third channel FET  74 . The first channel FET  70  is in communication with the PWM module  58  for filtering the PWM power signal and for outputting a first channel filtered PWM power signal The second channel FET  72  is in communication with the PWM module  58  for filtering the PWM power signal and for outputting a second channel filtered PWM power signal. The third channel FET  74  is in communication with the PWM module  58  for filtering the PWM power signal and for outputting a third channel filtered PWM power signal. Each of the first, second and third PWM power signals can be used to independently power individual DC loads, such as a DC motor, that require a power level being different from that of the fuel cell, as discussed in greater detail below. 
         [0017]    The DC-DC converter  20  further includes a first boost power circuit  76  and a buck power circuit  78 . The first boost power circuit  76  is in communication with the first channel FET  70  for receiving the first channel filtered PWM power signal. When enabled by the processor module  24 , the first boost power circuit  76  can increases the power level of the first channel filtered PWM power signal to output a first channel output power signal to be used by a first DC load. Specifically, the first channel output power signal has a power level ranging from 0 W to 3000 W. The buck boost power circuit is in communication with the first boost power circuit  76  and the first channel FET  70  for receiving the first channel filtered PWM power signal similar to the first boost power circuit  76 . When enabled by the processor module  24 , however, the buck power circuit  78  can decrease the power level of the first channel filtered PWM signal. Accordingly an output power signal can be utilized by a DC load requiring a lower power level than the power level provided by the fuel cell. The power level of the first channel output power signal delivered by the buck power circuit  78  ranges from 0 W to 3000 W. The first channel output power signal generated by either of the first boost power circuit  76  or the buck power circuit  78  is returned to the processor module  24  through the first channel output power port  40 . The feedback path allows the processor module  24  to monitor the first channel output power signal and to adjust the operation of the PWM module  58 , the first boost power circuit  76  and the buck power circuit  78 . The first boost power circuit  76  and the buck power circuit  78  are connected in a manner that each operate independent from one another, i.e., a buck-boost circuit  80 , while still outputting the first channel output power signal that may be utilized by a DC load. the processor module  24  being in communication with the first boost power circuit  76  and the buck power circuit  78  for receiving the first channel output power signal indicating the power output by one of the first boost power circuit  76  and the buck power circuit  78 . 
         [0018]    The DC-DC converter  20  further includes a second boost power circuit  82  being in communication with the PWM module  58  for receiving the second channel filtered PWM power signal. Similar to the first boost power circuit  76 , the second boost power circuit  82  increases the power level of the second channel filtered PWM power signal. Accordingly, the second boost power circuit  82  can output a second channel output power signal having a power level ranging from 0 W to 5000 W. The second channel output power signal generated by the second boost power circuit  82  is returned to the processor module  24  through the second channel output power port  50 . The feedback path allows the processor module  24  to monitor the second channel output power signal and to adjust the operation of the PWM module  58  and the second boost power circuit  82 . 
         [0019]    The DC-DC converter  20  includes a third boost power circuit  84  being in communication with the PWM module  58  for receiving the third channel filtered PWM power signal. Similar to the first and second boost power circuit  76 ,  82 , the third boost power circuit  84  increases the power level of the third channel filtered PWM power signal. Accordingly, the third boost power circuit  84  can output a third channel output power signal having a power level ranging from 0 W to 400 W. The third channel output power signal generated by the third boost power circuit  84  is returned to the processor module  24  through the third channel output power port  56 . The feedback path allows the processor module  24  to monitor the third channel output power signal and to adjust the operation of the PWM module  58  and the third boost power circuit  84 . 
         [0020]    A plurality of transistors  70 ,  86 ,  88 ,  90 ,  92 ,  94  is included to enable i.e., switch on and off the first boost power circuit  76 , the buck boost power circuit, the second boost power circuit  82  and the third boost power circuit  84 . Specifically, a first channel transistor  86  is in communication with the processor module  24  and the first channel FET  70 . The boost transistor  88  is in communication with the processor module  24  and the first boost power circuit  76 . The buck transistor  90  is in communication with the processor module  24  and the buck power circuit  78 . The processor module  24  enables the first channel FET  70  by outputting the first channel select signal to the first channel transistor  86 , which switches on the first channel FET  70  to deliver the first channel filtered PWM signal to the buck-boost circuit  80 . After enabling the first channel FET  70 , the processor module  24  determines whether to enable the first boost power circuit  76  or the buck power circuit  78 . When a DC load attached to the buck-boost circuit  80  requires power being less than power provided by the fuel cell, the processor module  24  outputs the buck signal to enable the buck power circuit  78  for decreasing the power level of the first channel filtered PWM signal. However, if the DC load requires power being greater than power provided by the fuel cell, the processor module  24  outputs a boost signal to enable the first boost power circuit  76  for increasing the power level of the first channel filtered PWM signal. 
         [0021]    The second channel transistor  92  is in communication with the processor module  24  and the second channel FET  72 . When a DC load is connected to the second boost power circuit  82 , the processor module  24  outputs the second channel select signal to the second channel transistor  92  to switch on the second channel FET  72 , thereby delivering the second channel filtered PWM signal to the second boost power circuit  82 . 
         [0022]    The third channel transistor  94  is in communication with the processor module  24  and the third channel FET  74 . When a DC load is connected to the third boost power circuit  84 , the processor module  24  outputs the third channel select signal to the third channel transistor  94  to switch on the third channel FET  74 , thereby delivering the third channel filtered PWM signal to the third boost power circuit  84 . 
         [0023]    The DC-DC converter  20  includes a plurality of sensors  96 ,  98 ,  100 ,  102 ,  104 ,  106 ,  108 ,  110 ,  112 ,  114  for sensing input currents, output currents at various locations of the DC-DC converter  20 . In regards to the first channel sub-circuit, the DC-DC converter  20  includes a first channel high input current sensor  98 , a first channel low input currents sensor, a first channel high output sensor, and a first channel low output sensor. The first channel high input current sensor  98  is in communication with the buck power circuit  78  and the first channel high input current port  34  for sensing high level current output from the fuel cell. The first channel high input current sensor  98  outputs an analog first channel high input current signal to the first channel high input current port  34  of the A-D converter  22 . The first channel low input sensor is in communication with the buck power circuit  78  and the first channel low input current port  32 . The sensor detects low level current output from the fuel cell and, in response, outputs an analog first channel low input current signal to the first channel low input port. The first channel high output current sensor  100  is in communication with the first boost power circuit  76  and the first channel high output current port  38 . The sensor detects high level current output by the first boost power circuit  76  and, in response, outputs an analog first channel high output current signal to first channel high output current port  38  of the A-D converter  22 . The first channel low output current sensor  102  is in communication with the first boost power circuit  76  and the first channel output current port. The sensor detects low level current output by the first boost power circuit  76  and, in response, outputs the analog first channel low output current signal to the first channel low output current port  36 . 
         [0024]    In regards to the second channel sub-circuit, the DC-DC converter  20  includes a second channel high input current sensor  104 , a second channel low input currents sensor, a second channel high output sensor, and a second channel low output sensor. The second channel high input current sensor  104  is in communication with the second boost power circuit  82  and the second channel high input current port  44 . The sensor detects high level current output from the fuel cell and, in response, outputs the analog second channel low input current signal to the A-D converter  22 . The second channel low input current sensor  106  is in communication with the second boost power circuit  82  and the second channel low input current port  42 . The sensor detects low level current output from the fuel cell and, in response, outputs the analog second channel low range input current signal to A-D converter  22 . The second channel high output current sensor  108  is in communication with the second boost power circuit  82  and the second channel high output current port  48 . The sensor detects high level current output by the second boost power circuit  82  and, in response, outputs the analog second channel high output current signal to the A-D converter  22 . The second channel low output current sensor  110  is in communication with the second boost power circuit  82  and the second channel low output current port  46 . The sensor detects low level current output by the second boost power circuit  82  and, in response, outputs the analog second channel low output current signal to the A-D converter  22 . 
         [0025]    Regarding the third channel sub-circuit, the DC-DC converter  20  includes a third channel input current sensor  112  and a third channel output sensor. The third channel input current sensor  112  is in communication with the third boost power circuit  84  and the third channel input current port  52 . The sensor detects current output by the fuel cell and, in response, outputs the analog third channel input current signal to the A-D converter  22 . The third channel output current sensor  114  is in communication with the third boost power circuit  84  and the third channel output current port  54 . The sensor detects current output by the third boost power circuit  84  and, in response, outputs the analog third channel output current signal to the A-D converter  22 . 
         [0026]    The DC-DC converter  20  allows for configurable predetermined input limits and configurable predetermined output limits to provide a user with maximum flexibility for applications requiring AC and DC power. Specifically, the DC-DC converter  20  allows a user to specify the maximum power to be delivered to the DC-DC converter  20  from the fuel cell. Additionally, a user can specify fuel cell operating voltage and a minimum fuel cell operating voltage. Accordingly, if the voltage of the fuel cell increases above or decreases below the specified voltage ranges, the processor module  24  will take safety measures to prevent damage to the DC-DC converter  20 , such as disenabling one of the first, second, or third channel sub-circuits or shutting down the entire DC-DC converter  20 . The DC-DC converter  20  also provides for user configurable first, second, and third output power levels depending on the desired electrical application. Specifically, a user can select the first channel output power signal to have a power level from 0 W to 3000 W, the second channel output power signal to have a power level from 0 W to 5000 W, and the third channel output power signal to have a power level from 0 W to 400 W. Additionally, a user can select which channel sub-circuit takes priority and can assign a ratio value for the available power to be shared between the first boost power circuit  76 , the buck power circuit  78 , the second boost power circuit  82 , and the third boost power circuit  84  if the maximum input power limit is exceeded. The DC-DC converter  20  further allows a user to input a power ramp rate, which may protect the fuel cell from damaging slew rates. Specifically, a user can input the range of voltage gain or decrease and the amount of time in which the DC-DC converter  20  will achieve that voltage gain or decrease. 
         [0027]    The DC-DC converter  20  includes a serial communications module  60 , a broadcast communications module  62  and an LCD module  64 , each allowing a user to configure the input parameters and output parameters mentioned above. The serial communications module  60 , such as a RS-232 and/or SC10 module, is in communication with the processor module  24  for receiving the predetermined inputs and predetermined outputs from a first remotely located input device. After receiving the predetermined inputs and outputs, the serial communications module  60  delivering the predetermined signals to the processor module  24 . 
         [0028]    The broadcast communications module  62 , such as a controller area network (CAN) module, is in communication with the processor module  24 . Similar to the serial communications module  60  above, the broadcast communications module  62  receives receiving the predetermined inputs and predetermined outputs from a first remotely located input device. After receiving the predetermined inputs and outputs, the serial communications module  60  delivering the predetermined signals to the processor module  24 . 
         [0029]    The liquid crystal display (LCD  116 ) module is in communication with the processor module  24 . The LCD module  64  includes a LCD interface  118  and a LCD  116 . The LCD interface  118  allows a user to select the predetermined inputs and outputs. Subsequently, the LCD interface  118  delivers the predetermined input and outputs to the processor module  24 . The LCD  116  is in communication with the LCD interface  118  and may display the predetermined inputs and outputs selected by the user. 
         [0030]    The DC-DC converter  20  includes a memory module  66  for storing values associated with the predetermined inputs and outputs. The processor module  24  is in communication with the memory module  66  reading the user selected predetermined inputs and outputs from memory. Furthermore, the processor module  24  compares at least one of the predetermined stored values to at least one of the plurality of digital power and current signals that are returned to the A-D converter  22  and ultimately the processor module  24 . Based on the comparison between the predetermined inputs and outputs selected by the user and the feedback digital power and current signals indicating the real time power levels and currents levels output by the DC-DC converter  20 , the processor module  24  can generate one of the select signals to initiate at least one of the first channel, the second channel and the third channel FETs to achieve an output power signal specified by the predetermined stored values. Accordingly, a multi-output DC-DC converter  20  is provided allowing for configurable input parameters for each output, such as maximum input power and maximum and minimum input voltage ranges and configurable output parameters for each output, such as output voltage, output current, and output power. 
         [0031]    As would be understood by persons of ordinary skill in the art, many modifications and variations of the described embodiments are possible in light of the above teachings and the invention may be practiced otherwise than as specifically described while within the scope of the appended claims. These described embodiments should be interpreted to cover any combination in which the inventive novelty exercises its utility.