WO2012150962A1

WO2012150962A1 - Full wave ac/dc voltage divider

Info

Publication number: WO2012150962A1
Application number: PCT/US2011/062825
Authority: WO
Inventors: Vladimir Borisov; Sudhir Thumaty
Original assignee: Itron, Inc.
Priority date: 2011-05-04
Filing date: 2011-12-01
Publication date: 2012-11-08
Also published as: CA2738844A1; CA2738844C

Abstract

Disclosed is apparatus and methodology for providing a capacitive voltage divider power supply. A plurality of full wave rectifiers each including a capacitor are coupled in series so that an applied AC source charges the capacitors in series. Switches associated with each of the plurality of full wave rectifiers are configured to be conductive during a time period spanning a period on either side of and including the zero crossing point of the applied AC source voltage. During this period of conduction, the switches provide discharge paths to discharge the capacitors in parallel into one or more load capacitors.

Description

TITLE: Full Wave AC/DC Voltage Divider

FIELD OF THE INVENTION

[0001] The present subject matter relates to voltage dividers. More particularly, the present subject matter relates to a full wave, series charge, parallel discharge capacitive voltage divider configured to provide a DC voltage from an AC supply.

BACKGROUND OF THE INVENTION [0002] Power supplies constructed using the known concept of serially charging a series of capacitors and discharging the series in parallel are known in the art. Such configurations may be used, for example, with variations in excitation, for a variety of configurations. In one example, U.S. Pat. No. 5,446,644 (Zhou) discloses a direct current (DC) voltage divider configuration employing a diode and capacitor configuration. In such '644 patent configuration, a DC supply is applied as the input to a diode and capacitor series circuit by way of a first switch. A second switch is configured to couple a number of diodes to the series connected capacitors to provide a parallel discharge path, Generally, such arrangement operates as a voltage divider in order to convert a relatively higher DC voltage to a relatively lower DC voltage. With an input DC voltage to such circuit, Zhou operates the switches alternately at a frequency chosen to produce a desired output voltage level. Such form of operation results in a somewhat selectively variable output voltage but at the cost of complex variable frequency alternating operation of such two switches.

[00031 Cubbison, Jr. (U.S. Pat. No. 4,649,468) discloses a voltage divider circuit employing a series charge/parallel discharge diode/capacitor circuit where the diodes provide the switching without additional switches. The circuit in such Cubbison, Jr. arrangement, however, provides sub-divided capacitors, with varying numbers of capacitors used directly connected in series to provide desired low voltage outputs. [0004] An "Analog Devices" article illustrates the use of a capacitor divider power supply in an electric meter. See, Analog Devices Application Note AN-687, "A Low Cost Tamper-Resistant Energy Meter Based on the ADE7761 with Missing Neutral Function" by English and Moulin, 2004, including material starting on page 7 of such publication under the title "Power Supply Design." A Linear Technology Magazine article illustrates a switch capacitor voltage regulator that is configured to provide current gain. See, Design Ideas, "Switched Capacitor Voltage Regulator Provides Current Gain" Linear Technology Magazine, February 1999.

[0005] Despite some benefits offered by such configurations and others, it would, nevertheless, be beneficial to provide a simplified series-parallel capacitor- rectifier voltage dividing circuit that was able to produce a regulated DC voltage from an alternating current (AC) input source.

[0006] While various implementations of series-parallel capacitor-rectifier voltage dividing circuits have been developed, and while various combinations of voltage divider circuits have been developed, no design has emerged that generally encompasses all of the desired characteristics as hereafter presented in accordance with the subject technology.

SUMMARY OF THE INVENTION

[0007] In view of the recognized features encountered in the prior art and addressed by the present subject matter, improved apparatus and methodology are provided for converting an AC source voltages to a DC voltage.

[0008] In an exemplary configuration, a full wave capacitive voltage divider power supply for reducing an alternating current (AC) from an AC source to a direct current (DC) is provided comprising at least one pair of full wave rectifiers each comprising a plurality of rectifiers and a capacitor. The pair of full wave rectifiers may be coupled in series such that the capacitors are charged in series during portions of both a positive and negative half cycle of an applied AC source. A pair of switches may be associated with each of the pair of full wave rectifiers and configured to be non-conductive during the charging portions of both a positive and negative half cycle of an applied AC source and conductive during a time period spanning a period on either side of and including the zero crossing point of the applied AC source. A load capacitor is provided and the switches are configured to provide parallel discharge paths from each of the capacitors to the load capacitor.

[0009] In selected embodiments, a resistor is coupled in series with the applied AC source and the pair of full wave rectifiers. In certain embodiments a second load capacitor is couple in series with the load capacitor and a common terminal between the second load capacitor and the load capacitor is coupled to a common line of the applied AC source so that both positive and negative direct current voltage relative to the common line of the applied AC source may be provided.

[0010] In particular embodiments at least one additional full wave rectifier and capacitor is coupled in series with the at least one pair of full wave rectifiers and at least one additional pair of switches is associated with said at least on additional full wave rectifier. The additional pair of switches is configured to be non-conductive during the charging portions of both a positive and negative half cycle of an applied AC source and conductive during a time period spanning a period on either side of and including the zero crossing point of the applied AC source.

[0011] In other embodiments of the present subject matter, a full wave capacitive voltage divider is provided comprising a plurality of full wave rectifiers each corresponding to a plurality of rectifiers and a capacitor. The plurality of full wave rectifiers are coupled in series such that the capacitors of each of the plurality of full wave rectifiers are charge in series during portions of both a positive and negative half cycle of an applied AC source. A pair of switches is associated with each of the plurality of full wave rectifiers and configured to be non-conductive during the charging portions of both a positive and negative half cycle of an applied AC source and conductive during a time period spanning a period on either side of and including the zero crossing point of the applied AC source. A load capacitor is coupled to the pair of switches so that when the pair of switches is conductive, each of the capacitors of each of the plurality of full wave rectifiers is discharged in parallel into the load capacitor.

[0012] The present subject matter also relates to power supply methodology for converting an alternating current (AC) from an AC source to a direct current (DC). An exemplary method comprises providing at least one pair of full wave rectifiers each configured as a plurality of rectifiers and a capacitor. The full wave rectifier pairs are coupled in series and an AC source is applied to the pair such that the capacitors are charged in series during portions of both a positive and negative half cycle of the applied AC source. A pair of switches is associated with each of the pair of full wave rectifiers and configured to be non-conductive during the charging portions of both a positive and negative half cycle of an applied AC source and conductive during a time period spanning a period on either side of and including the zero crossing point of the applied AC source. A load capacitor is provided and the switches are configured to provide parallel discharge paths from each of the capacitors to the load capacitor.

[0013] In certain embodiments, the methodology provides for coupling a resistor in series with the applied AC source and the pair of full wave rectifiers. In particular embodiments, the methodology provides for coupling a second load capacitor in series with the load capacitor, and coupling a common terminal between the second load capacitor and the load capacitor to a common line of the applied AC source.

[0014] One present exemplary embodiment in accordance with the present subject matter relates to a full wave capacitive voltage divider power supply for converting an alternating current (AC) from an AC source to a direct current (DC). Such present exemplary power supply preferably may comprise at least one pair of full wave rectifiers, each comprising a plurality of rectifiers and a rectifier capacitor, such pair of full wave rectifiers coupled in series such that such rectifier capacitors are charged in series during portions of both a positive and negative half cycle of an applied AC source; a pair of switches associated with each of such pair of full wave rectifiers, such switches configured to be non-conductive during the charging portions of both a positive and negative half cycle of an applied AC source, and configured to be conductive during a time period spanning a period on either side of and including the zero crossing point of the applied AC source; and a load capacitor, wherein such switches are configured to provide parallel discharge paths from each of such rectifier capacitors to such load capacitor.

[0015] In some present alternative, such an exemplary power supply may further comprise a resistor coupled in series with the applied AC source and such pair of full wave rectifiers. In other present alternatives, a present exemplary power supply may further comprise a second load capacitor couple in series with such load capacitor, wherein a common terminal between such second load capacitor and such load capacitor may be coupled to a common line of the applied AC source, whereby both positive and negative direct current voltage relative to the common line of the applied AC source may be provided.

[0016] Still other present alternative power supplies may further comprise at least one additional full wave rectifier and rectifier capacitor coupled in series with such at ieast one pair of full wave rectifiers; and at least one additional pair of switches associated with such at Ieast one additional full wave rectifier, such at Ieast one additional pair of switches configured to be non-conductive during the charging portions of both a positive and negative half cycle of an applied AC source and conductive during a time period spanning a period on either side of and including the zero crossing point of the applied AC source.

[0017] Another present exemplary embodiment of the present technology may relate to a full wave capacitive voltage divider, comprising a plurality of full wave rectifiers each comprising a plurality of rectifiers, and a rectifier capacitor, the plurality of full wave rectifiers coupled in series such that such capacitors of each of the plurality of full wave rectifiers are charged in series during portions of both a positive and negative half cycle of an applied AC source; a pair of switches associated with each of such plurality of full wave rectifiers, such pair of switches configured to be non-conductive during the charging portions of both a positive and negative half cycle of an applied AC source and conductive during a time period spanning a period on either side of and including the zero crossing point of the applied AC source; and a load capacitor coupled to such pair of switches. Per such present exemplary arrangement, advantageously, when such pair of switches is conductive, each of such rectifier capacitors of each of the plurality of full wave rectifiers may be discharged in parallel into such load capacitor.

[0018] Variations of such present voltage divider embodiments may further comprise a resistor coupled in series with the applied AC source and such pair of full wave rectifiers. Still further, optionally, such load capacitor may comprise a pair of capacitors connected in series. [0019] Those of ordinary skill in the art should understand from the complete disclosure herewith that the present subject matter equally relates to both apparatus as well as to corresponding and related methodology. One present exemplary method relates to power supply methodology for converting an alternating current (AC) from an AC source to a direct current (DC). Such an exemplary method may preferably comprise providing at least one pair of full wave rectifiers each configured as a plurality of rectifiers and a capacitor; coupling the pair of full wave rectifiers in series; applying an AC source to the pair of full wave rectifiers such that the capacitors are charged in series during portions of both a positive and negative half cycle of the applied AC source; associating a pair of switches with each of the pair of full wave rectifiers; configuring the pair of switches to be non-conductive during the charging portions of both a positive and negative half cycle of an applied AC source and conductive during a time period spanning a period on either side of and including the zero crossing point of the applied AC source; providing a load capacitor; and configuring the switches to provide parallel discharge paths from each of the respective capacitors of the rectifiers to the load capacitor.

[0020] Other present variations of such exemplary power supply

methodology may further comprise coupling a resistor in series with the applied AC source and the pair of full wave rectifiers. Other variations may further comprise coupling a second load capacitor in series with the load capacitor; and coupling a common terminal between the second load capacitor and the load capacitor to a common line of the applied AC source.

[0021] Still further, other optionally present exemplary methodology may further include coupling at least one additional full wave rectifier and capacitor in series with the at least one pair of full wave rectifiers; associating at least one additional pair of switches with the at least one additional full wave rectifier; and configuring the at least one additional pair of switches to be non-conductive during the charging portions of both a positive and negative half cycle of an applied AC source and conductive during a time period spanning a period on either side of and including the zero crossing point of the applied AC source.

[0022] Additional objects and advantages of the present subject matter are set forth in, or will be apparent to, those of ordinary skill in the art from the detailed description herein. Also, it should be further appreciated that modifications and variations to the specifically illustrated, referred and discussed features and elements hereof may be practiced in various embodiments and uses of the present subject matter without departing from the spirit and scope of the subject matter. Variations may include, but are not limited to, substitution of equivalent means, features, or steps for those illustrated, referenced, or discussed, and the functional, operational, or positional reversal of various parts, features, steps, or the like.

[0023] Still further, it is to be understood that different embodiments, as well as different presently preferred embodiments, of the present subject matter may include various combinations or configurations of presently disclosed features, steps, or elements, or their equivalents (including combinations of features, parts, or steps or configurations thereof not expressly shown in the figures or stated in the detailed description of such figures). Additional embodiments of the present subject matter, not necessarily expressed in the summarized section, may include and incorporate various combinations of aspects of features, components, or steps referenced in the summarized objects above, and/or other features, components, or steps as otherwise discussed in this application. Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the remainder of the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] A full and enabling disclosure of the present subject matter, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

[0025] Figure 1 is a schematic representation of a pair of full wave rectifier circuits coupled together in accordance with present technology to provide a voltage divider circuit and illustrating the charging paths for associated capacitors;

[0026] Figure 2 duplicates Figure 1 but illustrates the discharging paths for the associated capacitors;

[0027] Figure 3 is a schematic representation of a second embodiment of the present subject matter illustrating a pair of full wave rectifier circuits coupled together to provide a voltage divider circuit having both positive and negative outputs and illustrating the discharging paths for the associated capacitors; and [0028] Figure 4 is a schematic representation of a plurality of full wave rectifier circuits coupled together to provide higher levels of voltage rectification and division.

[0029] Repeat use of reference characters throughout the present specification and appended drawings is intended to represent same or analogous features, elements, or steps of the present subject matter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

10030] As discussed in the Summary of the Invention section, the present subject matter is particularly concerned with a full wave, series charge, parallel discharge capacitive voltage divider configured to provide a DC voltage from an AC supply.

[0031] Selected combinations of aspects of the disclosed technology correspond to a plurality of different embodiments of the present subject matter. It should be noted that each of the exemplary embodiments presented and discussed herein should not insinuate limitations of the present subject matter. Features or steps illustrated or described as part of one embodiment may be used in combination with aspects of another embodiment to yield yet further

embodiments. Additionally, certain features may be interchanged with similar devices or features not expressly mentioned which perform the same or similar function.

[0032] Reference will now be made in detail to the presently preferred embodiments of the subject full wave voltage divider. Referring now to the drawings, Figure 1 illustrates a schematic representation of a pair of full wave rectifier circuits coupled together in accordance with present technology to provide a voltage divider circuit 100 and illustrates charging paths 102, 104 for associated capacitors C-i, C₂ within the pair of full wave rectifiers.

[0033] As will be appreciated by those of ordinary skill in the art from an inspection of the schematic illustrated in Figure 1 , a first full wave rectifier is formed by a plurality of rectifier elements, herein illustrated as diodes Di, D2, Dg, and D ₀ that are configured to provide charge to capacitor Ci from an alternating current (AC) line source coupled across line input terminals 106, 108. Similarly, a second full wave rectifier is formed by a plurality of rectifiers herein illustrated as diodes D₃, D₄, D7g, and Ds that are configured to provide charge to capacitor C₂ from the AC line source coupled across line input terminals 106, 108. For reference purposes, line terminal 108 is representatively designated as a common potential terminal for all schematic diagrams herein illustrated.

[0034] Those of ordinary skill in the art should appreciate that rectification of an AC source may be provided in a number of ways, generally by using what may be commonly referred to as a "rectifier." For present purposes, such rectifiers may be provided in a number of ways using diodes as described in the remainder of the specification, but may also be provided using electro-mechanical and electro- magnetically operated switches, MOSFET devices, SCRs, TRIACs, and other types of solid state switching devices as well as such items as vacuum tube devices.

[0035] As may be seen from further inspection of Figure 1 , when line terminal 06 goes positive with respect to common terminal 108, charging current will flow through resistor R ₍ and then along a path 102 including diodes D₂, capacitor Ci, diodes D3, D₄, capacitor C₂, diode D₅ and back to common terminal 108. Through such charging path, capacitors Ci, C2 are charged in series during the positive half cycles of the voltage applied to line terminals 106, 108.

[0036] Resistor R_{1 p} in addition to providing current control of the charging path, provides efficient surge protection for the voltage divider circuit since, with capacitors Ci, C₂ being charged, the overall circuit represents a low-pass filter. In such manner, capacitors C-,, C₂ provide transient protection for the semiconductor devices during line surges. Due to the transient protection inherently provided by the present subject matter, other commonly used transient suppression devices such as metal oxide varistors (MOV), gas discharge tubes (GDT), and other transient voltage suppressor (TVS) devices are not as necessary but may be optionally provided.

[0037] In similar fashion, on the negative half cycles of the line voltage, a charging current will flow from common terminal 108 along a path 104 including diode D₆, capacitor C₂, diodes D₇, D₈, capacitor C-,, diodes D₉, D10 and back to line terminal 106. Again capacitors C₂ are charged in series from the AC line voltage applied across terminals 106, 108.

[0038] A further inspection of Figure 1 reveals the presence of four switching devices identified as switches Si, S2, S₃, and S₄. In the exemplary configuration illustrated in Figure 1 , such switching devices may correspond to transistors, and, in particular, to paired complimentary MOSFET transistors. It should be appreciated, however, that other types of switching device may be used. During the majority of both the positive and negative half cycles of the AC line voltage applied to terminals 106, 108, each of such switches Si, S2, S3, S₄ are in a non-conductive state.

[0039] During a portion of the time, in particular, a time period spanning a period on either side of and including the zero crossing point of the AC voltage applied across line terminals 06, 108, switches Si , S₂, S₃, and S₄ become conductive and provide discharge paths for the charge stored in capacitors C-i , C₂. As switches S-i, S₂, S₃, and S₄ become conductive, capacitors C _t C₂ are then discharged in parallel to provide an output voltage for the full wave voltage divider.

[0040] With reference now to Figure 2, it will be seen that Figure 2

duplicates Figure 1 but illustrates discharge paths 202, 204 for the associated capacitors C-i, C₂. In such instance, when the line voltage applied across terminals 106, 108 approaches the zero crossing point, switches Si, S₂, S_3l and S₄ all become conductive and provide first and second discharge paths 202, 204 that effectively discharge capacitors Ci , C₂ in parallel into output (Le., load) capacitor C₃ that has one terminal thereof coupled to an output terminal OUT and a second terminal thereof coupled to common potential at terminal 108.

[0041] With further reference to Figure 2, it will be seen that first discharge path 202 is formed from capacitor C s relatively positive side through now conductive switches S₃, S , diode D₁₃, through capacitor C₃ and back to the relatively negative terminal of capacitor Ci by way of path 206 through common potential terminal 08, diode D ₂ and switch S-i . In similar fashion, second discharge path 204 is formed from capacitor C₂ through conductive switch S₄, diode Di3 and capacitor C₃ and back to the relative negative terminal of capacitor C₂ by way of path 208 through common potential terminal 108, diode Dn and switch S₂. [0042] In such manner, capacitors Ci, C2 are charged in series as previously described with respect to Figure 1 and discharged in parallel into capacitor C3. Such process results in a divide by two operation so that the AC voltage applied to terminals 106, 108 is converted to direct current (DC) and applied to capacitor C₃ at about half the original level of the applied line voltage. One advantage of the divide by two operation is that the various component's voltage ratings require only one half that of the voltage applied to line terminals 106, 108. As will be seen in further embodiments, such ratio may be further reduced to the point that the component voltage ratings may be significantly lower than the voltage applied to line terminals 06, 08.

[0043] With reference to Figure 3, there is illustrated a schematic

representation of a second embodiment 300 of the present subject matter illustrating a pair of full wave rectifier circuits coupled together to provide a voltage divider circuit having both positive POS and negative NEG outputs and illustrating the discharging paths 202, 204, 306, 308 for the associated capacitors Ci, C₂.

[0044] By reference to both Figures 2 and 3, it will be noted that one additional component, capacitor C4, has been added to the circuit illustrated in Figure 2. By so doing, the common point connection 108 connecting diode Dn has been modified by placing capacitor C₄ in the series circuit through diode D-n and switch S₂. An important advantage is gained by this relatively simple addition in that a more symmetrical bipolar output can be provided while the division ratio increases two times so that the circuit operates as a divide by four circuit. A further advantage as alluded to above comes from the fact that now the individual component's voltage ratings need only be one fourth that of the voltage applied to line terminals 106, 108.

[0045] As the only change made in to the circuit illustrated in Figure 2 is within the discharge paths for capacitors Ci, C₂, it should be appreciated that the charging paths 202, 204 for capacitors C-i, C₂ in the embodiment illustrated in Figure 3 are identical to that illustrated in Figure 2 and so are designated by identical identifications. The discharge paths 306, 308 in this embodiment, however, have shifted somewhat as follows.

[0046] The discharge paths 202, 306 for capacitor C-i as noted are identical to path 202 of Figure 2, but changed in the Figure 3 embodiment so that after the discharge current flows from path 202 through capacitor C_3l the discharge path continues as discharge path 306 though common terminal 108, capacitor C₄, through diode Dn, switch S2, diode D12, and back to capacitor Ci through switch S-i. On the other hand, discharge path 204 from capacitor C₂ continues through capacitor C₃ and back to capacitor C2, as discharge path 308 by way of common terminal 108, capacitor C , diode Dn, and switch S₂.

[0047] In the instance of both discharge paths 306 and 308, charging voltage that was applied to capacitors Ci, C-2 in series has been discharged into capacitors C₃, C₄ in a series configuration by parallel discharge from capacitors Ci , C2. Such operation produces the previously mentioned divide by four effect.

[0048] With reference to Figure 4, there is illustrated a schematic

representation of a plurality of full wave rectifier circuits 400 coupled together to provide higher levels of voltage rectification and division. As illustrated in Figure 4, four cells are configured such that capacitors C₅, C₆, C₇, and CQ are charged in series and then discharged in parallel into capacitor C₉. Such functionality produces a full wave divide by four effect. In such instance, a low-voltage power supply is created where 240 VAC may be supplied to the line input and 60 VDC may be provided from the output terminal OUT.

[0049] Carrying such process forward, substantially any number of cells may be strung together in a manner identical to that of Figure 3. In one example, stringing twenty four cells together would provide a power supply where application of a 4.4 kVAC input to the line input terminals would provide 600 VDC at the output terminal OUT.

[0050] The present subject matter provides additional benefits from the fact that the switching frequency of the various switches is very low, generally only double the power line frequency of, for example, 50Hz or 60Hz. Further, the cost of implementing the full wave capacitive voltage divider in accordance with present technology is very low as the semiconductor and capacitor components are less expensive at the lower voltage ratings required.

[0051] It is also possible to fully integrate the present subject matter with the exception of the capacitors and, as noted with respect to Figure 4, the technology is very scalable so as to be able to provide a wide range of voltage supplies from an equally wide range of input voltages. Other features may also be easily implemented. For example, low-side voltage regulation may be achieved by controlled interruption of the discharge current from the string of cells into a load coupled across the output,

[0052] While the present subject matter has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.

Claims

WHAT IS CLAIMED IS:

1. A full wave capacitive voltage divider power supply for reducing an alternating current (AC) from an AC source to a direct current (DC), comprising: at least one pair of full wave rectifiers, each comprising a plurality of rectifiers and a rectifier capacitor, said pair of full wave rectifiers coupled in series such that said rectifier capacitors are charged in series during portions of both a positive and negative half cycle of an applied AC source;

a pair of switches associated with each of said pair of full wave rectifiers, said switches configured to be non-conductive during the charging portions of both a positive and negative half cycle of an applied AC source, and configured to be conductive during a time period spanning a period on either side of and including the zero crossing point of the applied AC source; and

a load capacitor,

wherein said switches are configured to provide parallel discharge paths from each of said rectifier capacitors to said load capacitor.

2. A power supply as in claim 1 , further comprising a resistor coupled in series with the applied AC source and said pair of full wave rectifiers.

3. A power supply as in claim 1 , further comprising:

a second load capacitor couple in series with said load capacitor, wherein a common terminal between said second load capacitor and said load capacitor is coupled to a common line of the applied AC source,

whereby both positive and negative direct current voltage relative to the common line of the applied AC source may be provided.

4. A power supply as in claim 1 , further comprising:

at least one additional full wave rectifier and rectifier capacitor coupled in series with said at least one pair of full wave rectifiers; and

at least one additional pair of switches associated with said at least one additional full wave rectifier, said at least one additional pair of switches configured to be non-conductive during the charging portions of both a positive and negative half cycle of an applied AC source and conductive during a time period spanning a period on either side of and including the zero crossing point of the applied AC source.

5. A full wave capacitive voltage divider, comprising:

a plurality of full wave rectifiers each comprising a plurality of rectifiers, and a rectifier capacitor, the plurality of full wave rectifiers coupled in series such that said capacitors of each of the plurality of full wave rectifiers are charged in series during portions of both a positive and negative half cycle of an applied AC source; a pair of switches associated with each of said plurality of full wave rectifiers, said pair of switches configured to be non-conductive during the charging portions of both a positive and negative half cycle of an applied AC source and conductive during a time period spanning a period on either side of and including the zero crossing point of the applied AC source; and

a load capacitor coupled to said pair of switches,

wherein, when said pair of switches is conductive, each of said rectifier capacitors of each of the plurality of full wave rectifiers are discharged in parallel into said load capacitor.

6. A voltage divider as in claim 5, further comprising a resistor coupled in series with the applied AC source and said pair of full wave rectifiers.

7. A voltage divider as in claim 5, wherein said load capacitor comprises a pair of capacitors co nected in series.

8. Power supply methodology for reducing an alternating current (AC) from an AC source to a direct current (DC), comprising:

providing at least one pair of full wave rectifiers each configured as a plurality of rectifiers and a capacitor;

coupling the pair of full wave rectifiers in series; applying an AC source to the pair of full wave rectifiers such that the capacitors are charged in series during portions of both a positive and negative half cycle of the applied AC source;

associating a pair of switches with each of the pair of full wave rectifiers; configuring the pair of switches to be non-conductive during the charging portions of both a positive and negative half cycle of an applied AC source and conductive during a time period spanning a period on either side of and including the zero crossing point of the applied AC source;

providing a load capacitor; and

configuring the switches to provide parallel discharge paths from each of the respective capacitors of the rectifiers to the load capacitor.

9. Power supply methodology as in claim 8, further comprising:

coupling a resistor in series with the applied AC source and the pair of full wave rectifiers.

10. Power supply methodology as in claim 8, further comprising:

coupling a second load capacitor in series with the load capacitor; and coupling a common terminal between the second load capacitor and the load capacitor to a common line of the applied AC source.

11. Power supply methodology as in claim 8, further comprising:

coupling at least one additional full wave rectifier and capacitor in series with the at least one pair of full wave rectifiers;

associating at least one additional pair of switches with the at least one additional full wave rectifier; and

configuring the at least one additional pair of switches to be non-conductive during the charging portions of both a positive and negative half cycle of an applied AC source and conductive during a time period spanning a period on either side of and including the zero crossing point of the applied AC source.