Energy storage and hold-up method and apparatus for high density power conversion

Abstract

A method and apparatus for adaptively configuring an array of voltage transformation modules is disclosed. The aggregate voltage transformation ratio of the adaptive array is adjusted to digitally regulate the output voltage for a wide range of input voltages. An integrated adaptive array having a plurality of input cells, a plurality of output cells, or a plurality of both is also disclosed. The input and output cells may be adaptively configured to provide an adjustable transformer turns ratio for the adaptive array or in the case of an integrated VTM, an adjustable voltage transformation ratio for the integrated VTM. A controller is used to configure the cells and provide digital regulation of the output. A converter having input cells configured as a complementary pair, which are switched out of phase, reduces common mode current and noise. Series connected input cells are used for reducing primary switch voltage ratings in a converter and enabling increased operating frequency or efficiency. An off-line auto-ranging power supply topology is disclosed. An auto-ranging converter module (“ACM”) includes 2 or more input cells magnetically coupled to an output cell providing auto-ranging, isolation, and voltage transformation. The ACM converts a rectified line voltage to a low DC bus voltage. The topology allows regulation and power factor correction to be provided at a low voltage increasing energy density and efficiency and reducing cost. A fully integrated PCM may also include a hold-up circuit, a DC input, and a power regulator with or without power factor correction. A PCM with PFC may combine the hold-up and smoothing capacitors for further increases in power density.

What is claimed is: 
     
       1. A method of converting power from a source at a source voltage for delivery to a load at a load voltage, where the source voltage may vary between a high line voltage and a low line voltage in a normal operating range, comprising:
 providing DC-DC voltage transformation and isolation in a first power conversion stage, the first stage having a CA input for receiving power from the source and a CA output; 
 providing power regulation in a second power conversion stage having a PR input for receiving power from the CA output of the first stage, regulation circuitry, and a PR output for delivering power to the load, the regulation circuitry being adapted to maintain the load voltage within a regulation range while the PR input voltage remains within a normal operating range; 
 providing a hold-up circuit having a charge path and a discharge path for connection to a hold-up capacitance, the discharge path providing a low impedance connection between the hold-up capacitance and the PR input for supplying power to the regulation circuitry, the charge path providing a charge current to charge the hold-up capacitance; 
 configuring the hold-up circuit to charge the hold-up capacitance when a first predetermined condition is satisfied and to provide power to the PR input when a second predetermined condition is satisfied. 
 
     
     
       2. The method of  claim 1  wherein the providing DC-DC voltage transformation and isolation further comprises providing an integrated adaptive converter array having a first input cell and a second input cell, each input cell having a respective number, P x , of turns, an output cell having a respective number, S x , of turns, magnetic coupling between the turns to form a transformer common to the first and second input cells and the output cell; and further comprising:
 configuring the input cells in a parallel connection for operation at the low line voltage and in a series connection for operation at the high line voltage. 
 
     
     
       3. The method of  claim 1  wherein the providing DC-DC voltage transformation and isolation further comprises:
 providing an array of two or more VTMs, each VTM having an input, an output, and a substantially fixed voltage transformation ratio, K=V out /V in , over the normal operating range, where V in  is the voltage across the respective VTM input and V out  is the voltage across the respective VTM output, and providing isolation between its input and its output; and 
 configuring the inputs of the VTMs in a parallel connection for operation at the low line voltage and in a series connection for operation at the high line voltage. 
 
     
     
       4. The method of  claim 1 ,  2 , or  3  further comprising providing circuitry for performing the method in a self-contained assembly having terminals for connecting to the CA input, the PR output, and the hold-up circuit, for installation as a unit, and providing the hold-up capacitor as a component external to the assembly. 
     
     
       5. The method of  claim 1  further comprising providing control circuitry adapted to detect the first and second predetermined conditions and to configure the hold-up circuit. 
     
     
       6. The method of  claim 5  wherein the control circuitry is adapted to detect an error signal from the regulation circuitry and the second predetermined condition comprises the error signal being outside a predetermined range. 
     
     
       7. The method of  claim 5  wherein the second predetermined condition comprises the source voltage being below a first predetermined level and the hold-up capacitor being charged above a second predetermined level. 
     
     
       8. The method of  claim 1  further comprising providing a DC input for receiving power from an external DC source directly coupled to the second power conversion stage. 
     
     
       9. The method of  claim 8  wherein the DC input is connected to the PR input via the discharge path. 
     
     
       10. The method of  claim 8  wherein the DC input is connected to the PR input via switch circuitry capable of blocking current flow in both directions when OFF and conducting current in both directions when ON; and further comprising turning the switch circuitry ON to connect the external DC source to the PR input. 
     
     
       11. The method of  claim 5  wherein the hold-up circuit comprises switch circuitry capable of blocking current flow in both directions when OFF and conducting current in both directions when ON; and further comprising controlling the switch circuitry to provide the charge path and the discharge path. 
     
     
       12. The method of  claim 5  further comprising providing a switch in the discharge path for connecting the hold-up capacitance to the PR input when the switch is ON. 
     
     
       13. The method of  claim 12  wherein the hold-up circuit comprises a current limiting element in the charge path. 
     
     
       14. The method of  claim 5 ,  9 , or  12  further comprising providing power factor correction in the regulation circuitry and providing a smoothing capacitance at the PR output. 
     
     
       15. The method of  claim 14  further comprising providing a boost circuit having an output connected to charge the hold-up capacitance. 
     
     
       16. The method of  claim 15  wherein the boost circuit comprises an input connected to the PR output. 
     
     
       17. The method of  claim 14  further comprising providing circuitry to switch a single capacitance between a first configuration and a second configuration wherein the capacitance is connected to the PR output as the smoothing capacitance in the first configuration and is connected to the hold-up circuit as the hold-up capacitance in the second configuration. 
     
     
       18. An apparatus comprising:
 a first power conversion stage for providing DC-DC voltage transformation and isolation, the first power conversion stage having a CA input for receiving power from a source at a source voltage and a CA output in which the source voltage may vary between a high line voltage and a low line voltage in a normal operating range;   a second power conversion stage for providing power regulation, the second power conversion stage having a PR input for receiving power from the CA output of the first power conversion stage, regulation circuitry, and a PR output for delivering power to a load,
 the regulation circuitry being configured to maintain a load voltage delivered to the load within a regulation range while the PR input voltage remains within a normal operating range; and 
   a hold-up circuit having a charge path and a discharge path, the discharge path providing a low impedance connection between a hold-up capacitance and the PR input for supplying power to the second power conversion stage, the charge path providing a charge current to charge the hold-up capacitance, in which the hold-up circuit is configured to charge the hold-up capacitance when a first predetermined condition is satisfied and to provide power to the PR input when a second predetermined condition is satisfied.    
     
     
       19. The apparatus of claim 18 wherein the first power conversion stage comprises an integrated adaptive converter array having a first input cell and a second input cell, each input cell having a respective number, Px, of turns, an output cell having a respective number, Sx, of turns, and magnetic coupling between the turns to form a transformer common to the first and second input cells and the output cell.  
     
     
       20. The apparatus of claim 19 wherein the input cells are connected in series and adapted to divide the source voltage across the first and second input cells.  
     
     
       21. The apparatus of claim 19, comprising control circuitry for configuring the input cells in a parallel connection for operation at a low line voltage and in a series connection for operation at a high line voltage.  
     
     
       22. The apparatus of claim 18 wherein the first power conversion stage comprises an array of two or more voltage transformation modules (VTMs), each VTM having an input, an output, and a substantially fixed voltage transformation ratio, K=Vout/Vin, over an operating range, where V in  is the voltage across the respective VTM input and Vout is the voltage across the respective VTM output, and each VTM output is isolated from the corresponding VTM input.  
     
     
       23. The apparatus of claim 22 wherein the inputs of the VTMs are connected in series and adapted to divide the source voltage across the VTM inputs of at least two of the two or more VTMs.  
     
     
       24. The apparatus of claim 22, comprising control circuitry for configuring the VTMs in a parallel connection for operation at a low line voltage and in a series connection for operation at a high line voltage.  
     
     
       25. The apparatus of claim 18 wherein the first power conversion stage, the second power conversion stage, and the hold-up circuit are configured as a self-contained assembly having terminals for connecting to the CA input, the PR output, and the hold-up circuit, for installation as a unit, in which the hold-up capacitor is a component external to the assembly.  
     
     
       26. The apparatus of claim 18, comprising control circuitry configured to detect the first and second predetermined conditions and to configure the hold-up circuit.  
     
     
       27. The apparatus of claim 18, comprising control circuitry configured to detect an error signal from the regulation circuitry, and the second predetermined condition comprises the error signal being outside a predetermined range.  
     
     
       28. The apparatus of claim 18 wherein the second predetermined condition comprises the source voltage being below a first predetermined level and the hold-up capacitor being charged above a second predetermined level.  
     
     
       29. The apparatus of claim 18, comprising a DC input for receiving power from an external DC source directly coupled to the second power conversion stage.  
     
     
       30. The apparatus of claim 18 wherein the DC input is connected to the PR input via the discharge path.  
     
     
       31. The apparatus of claim 18 wherein the hold-up circuit comprises switch circuitry capable of blocking current flow in both directions when OFF and conducting current in both directions when ON, and a control circuitry controls the switch circuitry to provide the charge path and the discharge path.  
     
     
       32. The apparatus of claim 18, comprising a switch in the discharge path for connecting the hold-up capacitance to the PR input when the switch is ON.  
     
     
       33. The apparatus of claim 18 wherein the hold-up circuit comprises a current limiting element in the charge path.  
     
     
       34. The apparatus of claim 18 wherein the second power conversion stage provides power factor correction, and the apparatus comprises a smoothing capacitance at the PR output.  
     
     
       35. The apparatus of claim 18, comprising a boost circuit having an output connected to charge the hold-up capacitance.  
     
     
       36. The apparatus of claim 35 wherein the boost circuit comprises an input connected to the PR output.  
     
     
       37. The apparatus of claim 18, comprising circuitry to switch a single capacitance between a first configuration and a second configuration wherein the capacitance is connected to the PR output as the smoothing capacitance in the first configuration and is connected to the hold-up circuit as the hold-up capacitance in the second configuration.  
     
     
       38. A method comprising:
 operating a power conversion module having a first power conversion stage, a second power conversion stage, and a hold-up circuit, including
 using the first power conversion stage to receive power from a source at a source voltage and provide DC-DC transformation and isolation, in which the source voltage may vary between a high line voltage and a low line voltage in a normal operating range; 
 using the second power conversion stage to deliver power to a load and regulate a load voltage at the load to be within a regulation range; 
 selectively connecting a single capacitance to (i) an output of the second power conversion stage such that the single capacitance functions as a smoothing capacitance, or (ii) the hold-up circuit such that the single capacitance functions as a hold-up capacitance; and 
 when the single capacitance functions as the hold-up capacitance,
 monitoring whether a first predetermined condition is satisfied, and charging the hold-up capacitance through a charge path in the hold-up circuit if the first predetermined condition is satisfied, and 
 monitoring whether a second predetermined condition is satisfied, and discharging the hold-up capacitance through a discharge path in the hold-up circuit if the second predetermined condition is satisfied, the discharge path providing a low impedance connection between the hold-up capacitance and an input of the second power conversion stage.  
 
   
     
     
       39. The method of claim 38 wherein the providing DC-DC voltage transformation and isolation further comprises using an integrated adaptive converter array having a first input cell and a second input cell, each input cell having a respective number, Px, of turns, an output cell having a respective number, Sx, of turns, and magnetic coupling between the turns to form a transformer common to the first and second input cells and the output cell.  
     
     
       40. The method of claim 39, comprising configuring the input cells in a parallel connection for operation at the low line voltage and in a series connection for operation at the high line voltage.  
     
     
       41. The method of claim 38 wherein the providing DC-DC voltage transformation and isolation further comprises using an array of two or more VTMs, each VTM having an input, an output, and a substantially fixed voltage transformation ratio, K=Vout/Vin, over the normal operating range, where Vin is the voltage across the respective VTM input and Vout is the voltage across the respective VTM output.  
     
     
       42. The method of claim 41, comprising configuring the inputs of the VTMs in a parallel connection for operation at the low line voltage and in a series connection for operation at the high line voltage.  
     
     
       43. The method of claim 41, comprising providing isolation between each VTM input and the corresponding VTM output.  
     
     
       44. The method of claim 38 further comprising using circuitry in a self-contained assembly having terminals for connecting to an input of the first power conversion stage, the output of the second power conversion stage, and the hold-up circuit, and using the hold-up capacitor as a component external to the assembly.  
     
     
       45. The method of claim 38, comprising using control circuitry to detect the first and second predetermined conditions and to configure the hold-up circuit.  
     
     
       46. The method of claim 38, comprising using a control circuitry to detect an error signal from the second power conversion stage, and wherein the second predetermined condition comprises the error signal being outside a predetermined range.  
     
     
       47. The method of claim 38 wherein the second predetermined condition comprises the source voltage being below a first predetermined level and the hold-up capacitor being charged above a second predetermined level.  
     
     
       48. The method of claim 38 further comprising receiving power from an external DC source, and coupling the external DC source directly to the second power conversion stage.  
     
     
       49. The method of claim 48, comprising connecting the external DC source to the input of the second power conversion stage via the discharge path.  
     
     
       50. The method of claim 38 wherein the hold-up circuit comprises switch circuitry capable of blocking current flow in both directions when OFF and conducting current in both directions when ON; and further comprising controlling the switch circuitry to provide the charge path and the discharge path.  
     
     
       51. The method of claim 38 further comprising using a switch in the discharge path for connecting the hold-up capacitance to the input of the second power conversion stage when the switch is ON.  
     
     
       52. The method of claim 38 wherein the hold-up circuit comprises a current limiting element in the charge path.  
     
     
       53. The method of claim 38 further comprising using the second power conversion stage to provide power factor correction and using a smoothing capacitance at the PR output.  
     
     
       54. The method of claim 38 further comprising using a boost circuit to charge the hold-up capacitance.  
     
     
       55. The method of claim 54, comprising connecting an input of the boost circuit to the output of the second power conversion stage.  
     
     
       56. The method of claim 1 in which the hold-up circuit comprises circuitry in the charge path to allow current to conduct in a single direction when charging the hold-up capacitance and blocking current from flowing in a reverse direction from the hold-up capacitance through the charge path.  
     
     
       57. The method of claim 1 wherein the providing DC-DC voltage transformation and isolation further comprises:
 providing an array of two or more VTMs, each VTM having an input, an output, and a substantially fixed voltage transformation ratio, K=V out /V in , over the normal operating range, where V in  is the voltage across the respective VTM input and V out  is the voltage across the respective VTM output, and   providing isolation between its input and its output,   the inputs of the VTMs being connected in series and adapted to divide the source voltage across the VTM inputs of at least two of the two or more VTMs.    
     
     
       58. The method of claim 1 wherein the providing DC-DC voltage transformation and isolation further comprises providing an integrated adaptive converter array having a first input cell and a second input cell, each input cell having a respective number, P x , of turns, an output cell having a respective number, S x , of turns, magnetic coupling between the turns to form a transformer common to the first and second input cells and the output cell, the input cells being connected in series and adapted to divide the source voltage across the first and second input cells.