Switched capacitor converter with multi-tap autotransformer

Abstract

Embodiments of the present disclosure generally relate to a switched capacitor converter with a multi-tap autotransformer. A power supply system includes a switched capacitor converter, a multi-tap autotransformer, and an output stage. The multi-tap autotransformer includes multiple primary windings. The switched capacitor converter includes multiple circuit paths coupled to the primary windings. For example, the first circuit path includes a first capacitor; the second circuit path includes a second capacitor. The power supply also includes a controller that controllably switches an input voltage to the first circuit path and the second circuit path, thereby transferring energy to the primary winding of the multi-tap autotransformer. The output stage of the power supply is coupled to receive energy from a combination of the first primary winding and the second primary winding of the multi-tap autotransformer. Via the received energy, the output stage generates an output voltage that supplies power to a load.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to a switched capacitor converter with a multi-tap autotransformer. Background Art

[0002] As the name implies, a conventional switched capacitor DC-DC converter converts a received DC input voltage into a DC output voltage.

[0003] In a conventional application, the input voltage of a conventional switched capacitor converter falls within a range of 40 VDC to 60 VDC. In this instance, the switches in the switched capacitor converter are controlled to transfer the charge stored in the corresponding capacitors, thereby converting the input voltage (such as 48 VDC) of the so-called 4:1 switched capacitor converter to an output voltage (such as 12 VDC). In other words, the conventional switched capacitor converter can be configured to convert a 48 VDC voltage to a 12 VDC voltage.

[0004] In order to avoid so-called hard switching in a switched capacitor converter, the switches in the switched capacitor converter are preferably switched when the voltage across them is close to zero and the current flowing through them is close to zero.

[0005] The undesirable hard switching in conventional switched-capacitor converters can be mitigated by placing a separate inductor in series with the corresponding capacitor in each stage of the switched-capacitor converter. This results in a resonant (or semi-resonant) switching converter. Such a switched-capacitor converter is sometimes referred to as a switched resonant tank converter (STC). The resonant tank circuit formed by the series connection of the inductor and capacitor has an associated resonant frequency that is based on the inductance and capacitance of these components.

[0006] Switching the switches in a conventional switched capacitor converter at the respective resonant frequencies results in so-called zero current switching (ZCS), which reduces switching losses and provides good power conversion efficiency. Summary of the Invention

[0007] The present disclosure includes the observation that the power conversion efficiency of conventional switched capacitor converters can be improved. For example, to this end, embodiments herein include providing novel ways to improve the performance of switched capacitor converters and efficiently generate a corresponding output voltage.

[0008] More specifically, according to one embodiment, a device (such as a power supply) includes a switched capacitor converter, a multi-tap autotransformer, and an output stage. The multi-tap autotransformer includes multiple primary windings and at least one secondary winding (such as multiple secondary windings). The switched capacitor converter includes multiple circuit paths coupled to the primary winding. For example, the first circuit path of the switched capacitor converter includes a first capacitor; the second circuit path of the switched capacitor converter includes a second capacitor. The power supply also includes a controller that controllably switches an input voltage to a first circuit path and a second circuit path (such as at a primary stage) to transfer energy to the primary winding of the multi-tap autotransformer. The output stage (such as a secondary stage) of the power supply is coupled to receive energy transferred from a combination of the first primary winding and the second primary winding of the multi-tap autotransformer. Via the received energy, the output stage generates an output voltage that supplies power to a load.

[0009] It should be noted that any one or more of the components of the power supply (such as a switched capacitor converter, a transformer, a multi-tap autotransformer, a voltage converter, a controller, etc.) can be implemented as hardware (such as a circuit), software (and corresponding execution instructions), or a combination of hardware and software.

[0010] According to other embodiments, a power supply as described herein includes a unique multi-tap autotransformer in which a first primary winding and a second primary winding are connected in series with respect to a secondary winding. More specifically, the first primary winding is connected in series with the secondary winding; and the second primary winding is connected in series with the secondary winding.

[0011] It should also be noted that the multi-tap autotransformer described herein can be configured such that the secondary winding is inductively coupled to the first and second primary windings. In one embodiment, the first, second, and secondary windings are magnetically coupled to one another. If desired, the secondary windings are center-tapped to facilitate generating an output voltage from the output of the center-tapped winding.

[0012] According to other embodiments, a power supply as described herein includes an inductor connected across a node of a multi-tap autotransformer. In one embodiment, the inductor is connected in parallel with one or more secondary windings of the multi-tap autotransformer. The inductor provides zero voltage switching (ZVS) of the switches in the switched capacitor converter. Additionally or alternatively, it should be noted that the zero voltage switching capability as described herein can be provided by the magnetizing inductance associated with the multi-tap autotransformer.

[0013] According to other embodiments, a switched capacitor converter includes a plurality of switches operable to transfer energy from a voltage source (such as an input voltage) to each of a first primary winding and a second primary winding during different portions of a control cycle for controlling the plurality of switches. In one embodiment, the switched capacitor converter includes a plurality of resonant circuit paths operable to transfer energy from the input voltage source to the first primary winding and the second primary winding. The first switch(es) of the switched capacitor converter selectively couples the first resonant circuit path to the input voltage; the second switch(es) of the switched capacitor converter couples the second resonant circuit path to the input voltage.

[0014] According to other embodiments, a switched capacitor converter includes a plurality of capacitors, such as a first capacitor and a second capacitor; a first resonant circuit path includes a combination of the first capacitor and a first primary winding; and a second resonant circuit path includes a combination of the second capacitor and the second primary winding. A controller switches between: i) coupling the first resonant circuit path (the combination of the first capacitor and the first primary winding) to an input voltage; and ii) coupling the second resonant circuit path (the combination of the second capacitor and the second primary winding) to an input voltage. In this example, the secondary winding of the multi-tap autotransformer receives energy from the plurality of different resonant circuit paths during different portions of a control cycle.

[0015] According to yet other embodiments, the first capacitor in the first resonant circuit path is a first flying capacitor of the switched capacitor converter; and the second capacitor in the second resonant circuit path is a second flying capacitor of the switched capacitor converter.

[0016] The embodiments herein are more useful than conventional techniques. For example, the novel power supply includes a switched capacitor converter, a multi-tap autotransformer, and a voltage converter, which together provide higher efficiency in converting an input voltage to a corresponding output voltage compared to conventional techniques. Such embodiments also provide lower energy losses during generation of the corresponding output voltage.

[0017] These and other more specific embodiments are disclosed in greater detail below.

[0018] It should be noted that any of the resources discussed herein may include one or more computerized devices, apparatuses, hardware, etc., which perform and / or support any or all of the method operations disclosed herein. In other words, one or more computerized devices or processors may be programmed and / or configured to operate as explained herein to perform the various embodiments described herein.

[0019] Other embodiments herein include software programs for performing the steps and / or operations outlined above and disclosed in detail below. One such embodiment includes a computer program product comprising a non-transient computer-readable storage medium (i.e., any computer-readable hardware storage medium) on which software instructions are encoded for subsequent execution. When the instructions are executed in a computerized device (hardware) having a processor, the processor (hardware) is programmed and / or caused to perform the operations disclosed herein. Typically, such an arrangement is provided as software, code, instructions, and / or other data (e.g., a data structure) or as an application-specific integrated circuit (ASIC), and the above-mentioned software, code, instructions, and / or other data are arranged or encoded on a non-transient computer-readable storage medium (such as an optical medium (e.g., CD-ROM), a floppy disk, a hard disk, a memory stick, a memory device, etc.) or other medium (such as firmware in one or more ROMs, RAMs, PROMs, etc.). Software or firmware or other such configurations can be installed on a computerized device so that the computerized device performs the technology described herein.

[0020] Thus, embodiments herein are directed to a method, system, computer program product, etc., that support the operations discussed herein.

[0021] One embodiment includes a computer-readable storage medium and / or system having instructions stored thereon to facilitate generation of an output voltage to power a load. The instructions, when executed by computer processor hardware, cause the computer processor hardware (such as one or more processor devices or hardware located in the same location or in different locations) to: receive energy from an input voltage source; controllably switch a plurality of capacitor circuit paths to transfer energy from the input voltage source to a first primary winding and a second primary winding of a multi-tap autotransformer operable to transfer energy to an output stage; and generate an output voltage at the output stage via the energy received from the multi-tap autotransformer to power the load.

[0022] For the sake of clarity, the order of the above steps has been added.It should be noted that any of the processing steps as discussed herein may be performed in any suitable order.

[0023] Other embodiments of the present disclosure include software programs and / or corresponding hardware to perform any of the method embodiment steps and operations summarized above and disclosed in detail below.

[0024] It should be understood that, as discussed herein, the systems, methods, apparatus, instructions on computer-readable storage media, and the like may also be embodied strictly as a software program, firmware, as a mixture of software, hardware, and / or firmware, or as hardware alone (such as within a processor (hardware or software), or within an operating system, or within a software application).

[0025] Further, it should be noted that although the embodiments discussed herein may be applied to controlling the operation of a switched capacitor converter, the concepts disclosed herein may be advantageously applied to any other suitable voltage converter topology.

[0026] Additionally, it should be noted that while each of the various features, techniques, configurations, etc. herein may be discussed at various locations within the disclosure, it is intended that each of the concepts may be optionally implemented independently of one another or in combination with one another, where appropriate. Thus, one or more of the present inventions described herein may be embodied and viewed in many different ways.

[0027] Furthermore, it should be noted that the preliminary discussion of the embodiments herein (Summary of the Embodiments) purposefully does not specify every embodiment and / or additional novel aspect of the present disclosure or the claimed invention(s). Instead, this Summary of the Invention provides only general embodiments and corresponding novel aspects relative to conventional techniques. For additional details and / or possible viewpoints (arrangements) of the invention(s), the reader is directed to the "Detailed Description" section of the present disclosure (which is an overview of the embodiments) and the corresponding figures, as further discussed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is an example diagram illustrating a power supply including a switched capacitor converter and a multi-tap autotransformer according to embodiments herein.

[0029] Figure 2 is an example diagram illustrating a more detailed rendering of a controller and a power supply including a switched capacitor converter and a multi-tap autotransformer according to embodiments herein.

[0030] Figure 3 is an example timing diagram illustrating the timing of control signals according to embodiments herein.

[0031] Figure 4 is an example diagram illustrating a timing diagram of control signals and output signals according to embodiments herein.

[0032] Figure 5 is an example diagram illustrating a first mode of controlling switches in a switched capacitor converter according to embodiments herein.

[0033] Figure 6 is an example graph illustrating dead time or deactivation of switches in a switched capacitor converter according to embodiments herein.

[0034] Figure 7 is an example diagram illustrating a second mode of controlling switches in a switched capacitor converter according to embodiments herein.

[0035] Figure 8 is an example graph illustrating dead time or deactivation of switches in a switched capacitor converter according to embodiments herein.

[0036] Figure 9 is an example diagram illustrating details of a multi-tap autotransformer according to embodiments herein.

[0037] Figure 10 is an example diagram illustrating details of a multi-tap matrix autotransformer (with 2 basic autotransformers) according to embodiments herein.

[0038] Figure 11 is an example diagram illustrating details of a (matrix) multi-tap autotransformer (with M elementary autotransformers) according to embodiments herein.

[0039] Figure 12 is an example diagram illustrating a computer architecture operable to perform one or more operations according to embodiments herein.

[0040] Figure 13 is an example diagram illustrating a general method according to embodiments herein.

[0041] The foregoing and other objects, features, and advantages of the embodiments herein will become apparent from the following more particular description thereof, as illustrated in the accompanying drawings, in which like reference numerals refer to the same parts throughout the different views. The drawings are not necessarily drawn to scale, emphasis instead being placed upon illustrating the embodiments, principles, concepts, etc. DETAILED DESCRIPTION

[0042] According to one embodiment, as further discussed herein, a device such as a power supply system includes a switched capacitor converter, a novel multi-tap autotransformer, and an output stage. The multi-tap autotransformer includes multiple primary windings and at least one secondary winding (such as multiple secondary windings). The switched capacitor converter includes multiple circuit paths coupled to the primary winding. For example, the first circuit path of the switched capacitor converter includes a first capacitor; the second circuit path of the switched capacitor converter includes a second capacitor. The power supply also includes a controller that controllably switches an input voltage to the first circuit path and the second circuit path to transfer energy to the primary winding of the multi-tap autotransformer. The output stage of the power supply (such as comprising the second winding of the multi-tap autotransformer) is coupled to receive energy transferred from a combination of the first primary winding and the second primary winding of the multi-tap autotransformer. Via the energy received at the secondary winding, the output stage generates an output voltage that supplies power to a load.

[0043] Now, more specifically, Figure 1 is an example diagram illustrating a power supply including a switched capacitor converter and a multi-tap autotransformer according to embodiments herein.

[0044] As shown in this example embodiment, a power supply 100 (such as a device, electronic device, etc.) includes a controller 140 and a voltage converter 135. The voltage converter 135 includes a primary stage 101 and a secondary stage 102.

[0045] The primary stage 101 includes a switched capacitor converter 131, which includes a switch 125, a first primary winding 161-1 and a second primary winding 161-2 of a multi-tap autotransformer 160. It should be noted that the multi-tap autotransformer 160 is shown by way of a non-limiting example embodiment and can be exemplified as any suitable device, such as a transformer, a transformer device, a transformer assembly, etc. The secondary stage includes a secondary winding 162 of the multi-tap autotransformer 160 and associated circuitry that generates an output voltage 123 (Vout, such as typically a DC voltage). The secondary winding 162 includes a first secondary winding 162-1 and a second secondary winding 162-2.

[0046] It should be noted that each of the resources described herein may be instantiated in any suitable manner. For example, each of the controller 140, the switched capacitor converter 131, the multi-tap autotransformer 160, etc. may be instantiated as hardware (such as a circuit), software (executable instructions), or a combination of hardware and software resources or include hardware (such as a circuit), software (executable instructions), or a combination of hardware and software resources.

[0047] During operation, the controller 140 generates control signals 105 (such as one or more pulse width modulated signals) that control the states of corresponding control switches 125 in the switched capacitor converter 150 .

[0048] Further, as shown, switched capacitor converter 150 receives input voltage 120 (Vin, such as a DC input voltage) supplied to switched capacitor converter 131. As previously discussed, multi-tap autotransformer 160 includes a first primary winding 161-1 and a second primary winding 162-1. In one embodiment, primary winding 161 is at least inductively coupled to secondary winding 162. According to other embodiments, primary winding 161 is connected in series with secondary winding 162.

[0049] Further, as discussed herein, the controller 140 of the power supply 100 can controllably switch multiple capacitors and corresponding resonant circuit paths including the primary winding 161 of the multi-tap autotransformer 160 to transfer energy from the input voltage (Vin) through the primary winding 161 to the secondary winding 162 to generate the output voltage 123.

[0050] Figure 2 is an example diagram illustrating a switched capacitor converter according to embodiments herein.

[0051] As shown, the power supply 100 includes a voltage source Vin, a switched capacitor converter 131 , and a multi-tap autotransformer 160 .

[0052] The switched capacitor converter 131 (such as hardware, circuitry, etc.) includes a plurality of switches Q1, Q2, Q3, Q4, Q5, and Q6 (such as field-effect transistors or any other suitable type of switch). Additionally, the switched capacitor converter 150 includes a plurality of circuit components, including an inductor Lzvs, a capacitor Cres1, and a capacitor Cres2.

[0053] Furthermore, in this exemplary embodiment, multi-tap autotransformer 160 includes a primary winding 161-1 (e.g., N1 turns), a primary winding 161-2 (e.g., N1 turns), a secondary winding 162-1 (e.g., N2 turns), and a secondary winding 162-2 (e.g., N2 turns). The number of windings associated with primary winding 161 and / or secondary winding 162 (N1, N2, etc.) can be any suitable value and varies depending on the embodiment.

[0054] In one embodiment, the primary winding and the secondary winding of the multi-tap autotransformer 160 are connected in series. For example, the primary winding 161-1 is connected in series with the secondary winding 162-1; the secondary winding 162-1 is connected in series with the secondary winding 162-2; and the secondary winding 162-2 is connected in series with the primary winding 161-2.

[0055] According to other embodiments, the secondary winding 162 (such as a tapped secondary winding or multiple secondary windings connected in series) is inductively coupled to the first primary winding 161-1 and the second primary winding 161-2. In other words, as shown, the first primary winding 161-1, the second primary winding 161-2, and the secondary winding (s) 162 are magnetically coupled to each other. If desired, the secondary winding 162 can be a center-tapped winding, thereby facilitating the generation of the output voltage 123 from the corresponding output of the center-tapped winding.

[0056] Further, in this example embodiment, the drain node (D) of the switch Q1 and the drain node (D) of the switch Q4 are connected to the input voltage source Vin.

[0057] Furthermore, the source node (S) of switch Q1 is coupled to the drain node (D) of switch Q2 (node 213). The source node (S) of switch Q4 is coupled to the drain node (D) of switch Q5 (node 214). The source node (S) of switch Q2 is coupled to node 211. The source node (S) of switch Q5 is coupled to node 212.

[0058] Capacitor Cres1 is connected between node 213 and a corresponding node of primary winding 161-2. Capacitor Cres2 is connected between node 214 and a corresponding node of primary winding 161-1.

[0059] Inductor Lzvs is coupled in parallel to primary winding 161 and is provided between nodes 211 and 212 .

[0060] The drain (D) of the switch Q3 is connected to the node 211; the source (S) of the switch Q3 is connected to the ground. The drain (D) of the switch Q6 is connected to the node 212; the source (S) of the switch Q6 is connected to the ground.

[0061] The center tap (com node) of the secondary winding 162 outputs a current Iout and a corresponding output voltage 123 to drive a load 118 (also referred to as Ro).

[0062] In one embodiment, the amplitude of output voltage 123 is Vin / 8. Thus, if Vin = 48 VDC, the amplitude of output voltage 123 is 6 volts. However, as discussed herein, the settings of the components in power supply 100 can be adjusted to produce any suitable value of output voltage 123 (Vout). In general, output voltage 123 is: Vout = Vin*(N2 / (2*(2N2+N1))), where N1 = the number of turns on primary winding 161, and N2 is the number of turns on each of secondary windings 162.

[0063] In one embodiment, N1 is defined as the number of turns of each primary winding, while N2 is defined as the number of turns of each secondary winding; in this case, Vout=Vin*N2 / (2*(2*N2+N1)).

[0064] Further, as shown, during operation, controller 110 generates control signals 105 - 1 and 105 - 2 .

[0065] Further, in this example embodiment, the control signal 105-1 generated by the controller 140 drives the gates (G) of the respective switches Q1, Q3, and Q5. Thus, the control signal 105-1 controls the state of each of the switches Q1, Q3, and Q5.

[0066] Control signal 105-1 drives the respective gates (G) of switches Q1, Q3, and Q5. Thus, control signal 105-2 controls the state of each of switches Q2, Q4, and Q6.

[0067] It should be noted that each of the switches as described herein may be any suitable device, such as a (metal oxide semiconductor) field effect transistor, a bipolar junction transistor, or the like.

[0068] The capacitors Cres1 and Cres2 can be set to any suitable value. In one embodiment, the voltage converter 135 described herein provides better performance when Cres1=Cres2 and can work well even if Cres1≠Cres2.

[0069] The inductor Lzvs can be of any suitable value. Figure 4 The discussion in the associated text Figure 4 An example arrangement of an inductor Lzvs that provides zero voltage switching to switches in the power supply 100 is indicated.

[0070] Reference again Figure 2In one embodiment, there is optionally an additional inductor (such as an inductor Lzvs) connected in parallel with the multi-tap autotransformer 160 to achieve zero voltage switching (ZVS) of one or more switches Q1-Q6. As discussed further below, the Lzvs inductor can alternatively be integrated into the multi-tap autotransformer 161 (such as by gaps in the corresponding cores or by using a core with lower magnetic permeability).

[0071] As previously discussed, the switches in the power supply 100 are divided into two switch groups: the first switch group includes switches Q1, Q3 and Q5 controlled by corresponding control signals 105-1, and the second switch group includes switches Q2, Q4 and Q6 controlled by corresponding control signals 105-2, which are generally 180 degrees phase-shifted relative to the timing of the control signal 105-1.

[0072] In one embodiment, the pulse width modulation of the control signal 105 is approximately 50% to obtain the minimum RMS current.

[0073] The magnitude of the output voltage 123 depends on the number of turns (# of windings ratio N1 / N2 of primary winding to secondary winding). In one embodiment, the switching frequency does not directly change the magnitude of the output voltage, but generally speaking, it is changing the magnitude of the output voltage because the losses increase or decrease based on the difference between Fres and Fsw and the leakage of the multi-tap autotransformer when Cres1=Cres2, where Fres is the resonant frequency of the resonant tank formed by Cres1 or Cres2.

[0074] The embodiments herein include utilizing the leakage inductance Lk of the multi-tap autotransformer 160 to (soft) charge the capacitors Cres1 and Cres2 during different control cycles. For example, in one embodiment, the capacitors Cres1 and Cres2 act as flying capacitors, thereby enabling the use of lower voltage field effect transistors (switched capacitor converter 131) on the primary side compared to the classic LLC topology.

[0075] It should be noted that another benefit of the switched capacitor converter 131 as discussed herein is the symmetrical behavior of such a circuit. For example, as further discussed herein, via the implementation of power supply 100: i) compared to other techniques, the switched capacitor converter 131 is powered nearly continuously from the input power supply Vin at different times during the corresponding control cycle, thereby reducing input current ripple; ii) in the equivalent resonant tank switching circuit paths of the switched capacitor converter (such as the first resonant circuit path including capacitor Cres1 and primary winding 161-2 and the second resonant circuit path including capacitor Cres2 and primary winding 161-1), both resonant capacitors resonate with the leakage inductance Lk of the multi-tap autotransformer. In one embodiment, if Cres1≠Cres2, the resonant transition is unbalanced, which is not a practical operational issue. Generally speaking, if the difference is the maximum difference between Cres1 and Cres2 based on tolerance (i.e., ±10% ±20%), the converter still operates with high efficiency. In this example, the converter still operates normally due to ZVS operation.

[0076] It should also be noted that one enabler of the high efficiency and high power density of the proposed power supply 100 is the ability to implement lower voltage rated field effect transistors and to implement Class II ceramic capacitors (such as capacitors Cres1 and Cers2) that inherently provide high capacitance density.

[0077] Furthermore, as previously discussed, the additional inductor Lzvs provides inductive energy to ensure, for example, ZVS transitions of all field effect transistors in the switched capacitor converter 131 during all switching conditions. For example, the energy stored in the inductor Lzvs supplies charge to the parasitic capacitors of the corresponding switches during dead times, such as between times T1 and T2, between times T3 and T4, etc., as discussed further below.

[0078] Figure 3 is an example diagram illustrating generation of control signals to control a switched capacitor converter and a corresponding voltage converter according to embodiments herein.

[0079] Generally speaking, the controller 110 generates the control signal 105-2 as the inverse of the control signal 105-1 as shown in the graph 300. The pulse width of each control signal is approximately 49% or other suitable pulse width modulation value.

[0080] Between time T0 and time T1, when control signal 105-1 (at a logic high level) controls the set of switches Q1, Q3, and Q5 to an ON state (low impedance or short circuit), control signal 105-2 (logic low) controls the set of switches Q2, Q4, and Q6 to an OFF state (very high impedance or open circuit).

[0081] Conversely, between time T2 and time T3, when control signal 105-2 (logic high) controls the set of switches Q2, Q4, and Q6 to the ON state, control signal 105-1 (logic low) controls the set of switches Q1, Q3, and Q5 to the OFF state.

[0082] It should be noted that the duration between time T1 and time T2, the duration between time T3 and time T4, the duration between T5 and T6, etc. represent so-called dead times, during which each of the switches (Q1-Q6) in the power supply 100 is disabled to the OFF state.

[0083] Furthermore, as shown, the control signal 105 is periodic. For example, the settings of the control signal 105 in subsequent periods are the same as the settings of the control signal in the period between time T0 and time T4. More specifically, the settings of the control signal 105 generated by the controller 110 between time T3 and time T7 are the same as the settings of the control signal 105 between time T0 and time T3, etc.

[0084] In one embodiment, the controller 110 controls the frequency of the control signal (the period being the time between T0 and T4 ) which may be generated at any suitable frequency.

[0085] Additionally, as previously mentioned, although the control signal 105 may be generated with any suitable pulse width modulation value, the controller 110 controls the pulse duration of the control signal 105 to be approximately 49% in accordance with the dead time.

[0086] The magnitude of the output voltage 123 depends on the turns ratio (N1 / N2) of the multi-tap autotransformer 160. The ratio between the input voltage Vin and the output voltage Vout is given by: Vin / Vout = 4 + [(2*N1) / N2]

[0087] Therefore, by designing only the ratio between N1 and N2, the power converter described in this article can be extended to different conversion ratios, which actually leads to the claim of a new family of non-adjustable hybrid dc-dc converters with different possible ratios of Vin / Vout (such as 5:1, 6:1, 7:1, 8:1, etc.).

[0088] It should be noted that other embodiments herein utilize the leakage inductance of the multi-tap autotransformer 160 to softly charge capacitors Cres1 and Cres2, which act as flying capacitors, thereby enabling the use of lower voltage-dependent MOSFETs in the primary side (primary stage 101) compared to conventional (classic) LLC converter topologies. Switches Q1 and Q4 block a portion of the input voltage, which can be defined by the following equation: Vmax(Q1, Q4) = Vin / 2 + Vout*N1 / N2

[0089] During operation, switches Q2 and Q5 must block the entire input voltage Vin, while switches Q3 and Q6 must block 2*Vout.

[0090] As previously discussed, another benefit of the power supply as described herein is its symmetrical behavior, which provides the benefit of providing power to the dynamic load 118 from the input power supply Vin at all times during each phase, thereby reducing current / voltage ripple on the output voltage 123 .

[0091] It should also be noted that the magnitude of the output voltage 123 (Vout) depends on the number of turns (the number of windings N1 and N2 associated with the primary winding 161 and the secondary winding 162; N1 is the number of turns of each primary winding, and N2 is the number of turns of each secondary winding. In this example, the following relationship exists between the input and output: Vin / Vout=4+[(2*N1) / N2]). These can be selected to any suitable setting. Thus, the properties of the switched capacitor converter 120 can be modified to convert any input voltage level to a corresponding desired (such as unregulated) output voltage level.

[0092] Figure 4 is an example diagram illustrating a timing diagram of output signals according to embodiments herein.

[0093] In this example embodiment, as previously discussed, voltage Vx indicates the voltage at node 211 between primary winding 161 - 1 and secondary winding 162 - 1 ; voltage Vy indicates the voltage at node 212 between primary winding 161 - 2 and secondary winding 162 - 2 .

[0094] Icres1 represents the current passing through the series combination of the capacitor Cres1 and the primary winding 161 - 2 ; Icres2 represents the current passing through the series combination of the capacitor Cres2 and the primary winding 161 - 1 .

[0095] Izvs represents the current passing through the inductor Lzvs.

[0096] Is1 represents the current passing through the secondary winding 162 - 1 ; Is2 represents the current passing through the secondary winding 162 - 2 .

[0097] Iout (the sum of current Is1 and current Is2) represents the output current (Iout) supplied to the dynamic load 118 by the center tap of the secondary winding 162 of the multi-tap autotransformer 160. Between time T0 and time T1, when the resonant circuit path including capacitor Cres1 and primary winding 161-2 is coupled to the input voltage via the activated switch Q1, the corresponding generated current Is1 contributes the majority of the current to generate the current Iout. Conversely, between time T2 and time T3, when the resonant circuit path including capacitor Cres2 and primary winding 161-1 is coupled to the input voltage via the activated switch Q2, the corresponding generated current Is2 contributes the majority of the current to generate the current Iout.

[0098] Figure 5 is an example diagram illustrating a first mode (Phase #1) of controlling switches in a switched capacitor converter and a voltage converter according to embodiments herein.

[0099] For phase #1, between time T0 and time T1, in ZVS and zero current switching (ZCS), switches Q2, Q4 and Q6 are turned off; switches Q1, Q3 and Q5 are turned on, and the first resonant mode transition occurs between capacitor Cres1 and the leakage inductance of the multi-tap autotransformer, while the second resonant mode transition occurs between capacitor Cres2 and the leakage inductance of the multi-tap autotransformer 160.

[0100] In this example, during phase #1, capacitor Cres1 is soft charged from the input voltage source Vin, while capacitor Cres2 is soft discharged.

[0101] More specifically, as previously discussed, the primary winding 161 of the multi-tap autotransformer 160 includes a first node 211 and a second node 212. During time T0 to time T1 (the first resonant frequency mode), the controller 140 generates a first switching circuit path connecting capacitor Cres1 to the input voltage Vin. The controller 140 also generates a second switching circuit path by connecting capacitor Cres2 to node 212. As previously discussed, in this example, capacitor Cres1 is soft-charged via the input voltage Vin, and capacitor Cres2 (the flying capacitor is charged to Vin / 2) is soft-discharged. Thus, during phase #1, both resonant circuit paths contribute to varying degrees to the generation of the output voltage 123 that supplies power to the load 118.

[0102] When the capacitance is substantially equal, such as the capacitance of Cres1 = the capacitance of Cres2, the RMS (root mean square) current through each capacitor is approximately equal. If there is a perfect balance between the actual resonant current through capacitor Cres1 and capacitor Cres2, then i(Cres1)(t) = -i(Cres2)(t), and considering i(Cres1)(t) = Ires(t), it can be concluded that Is2(t) = 2*Ires(t). In this scenario, the following equation is valid in phase #1:

[0103] N1*Ires(t)+N1*Ires(t)=N2*Is1(t)-N2*Is2(t)

[0104] It can be written as:

[0105] Is1(t)=[(2*N1) / N2+2]*Ires(t), such as Figure 4 shown.

[0106] Generally speaking, in this phase #1, the converter exhibits two resonant modes based on the actual values of Cres1 and Cres2. For example, Cres1 faces a resonant current, where the resonant switch is defined by Fres1 = 1 / (2*pi*sqrt(Cres1*Lk)), where Lk is the leakage of the multi-tap autotransformer.

[0107] At the same time, Cres2 faces the resonant current, where the resonant switch is defined by Fres2 = 1 / (2*pi*sqrt(Cres2*Lk)), where Lk is the leakage of the multi-tap autotransformer.

[0108] Figure 6 is an example graph illustrating dead time or deactivation of all switches in a switched capacitor converter and a voltage converter according to embodiments herein.

[0109] Between time T1 and time T2, the controller 140 turns off switches Q1, Q3, and Q5. The parasitic capacitance of Q1 is charged to Vin / 2+Vout*N1 / N2; switch Q3 is charged to 2*Vout; switch Q5 is charged at the input voltage Vin, and the parasitic capacitance of switches Q2, Q4, and Q6 is discharged to zero using the inductive energy stored in inductor Lzvs. When the capacitance of switches Q2, Q4, and Q6 is discharged to zero, their body diodes begin to conduct to enable ZVS to turn on. The current Izvs(T1) that enables ZVS operation is represented as i(Lzvs,pk), as shown in Figure 4 As shown, it is given by the following equation:

[0110]

[0111] In one embodiment, the value of Lzvs depends largely on the application, and it basically depends on the input voltage, output voltage, and the MOSFET used in the application.

[0112] Figure 7 is an example diagram illustrating a second mode (also referred to as phase #3) of controlling switches in a switched capacitor converter and a voltage converter according to embodiments herein.

[0113] For phase #3, between time T2 and time T3, at t=T2, switches Q2, Q4 and Q6 are turned on in ZVS and ZCS; switches Q1, Q3 and Q5 are turned off in ZVS and zero current switching (ZCS), and the first resonant mode transition occurs between capacitor Cres1 and the leakage inductance of the multi-tap autotransformer, while the second resonant mode transition occurs between capacitor Cres2 and the leakage inductance of the multi-tap autotransformer 160.

[0114] In this example, during phase #3, capacitor Cres2 is soft charged from the input voltage source Vin, while capacitor Cres1 is soft discharged.

[0115] More specifically, as previously discussed, the primary winding 161 of the multi-tap autotransformer 160 includes a first node 211 and a second node 212. During time T2 to time T3 (the second resonant frequency mode), the controller 140 generates a first switching circuit path connecting capacitor Cres2 to the input voltage Vin via switch Q4. The controller 140 also generates a second switching circuit path by connecting capacitor Cres1 to node 211. As previously discussed, in this example, capacitor Cres1 (the flying capacitor) is soft-discharged, and capacitor Cres2 (charged to Vin / 2) is soft-charged. Thus, during phase #3, both resonant circuit paths contribute, to varying degrees, to the generation of the output voltage 123 that supplies power to the load 118.

[0116] When the capacitance is substantially equal, such as the capacitance of Cres1 = the capacitance of Cres2, the RMS (root mean square) current through each capacitor is approximately equal. If there is a perfect balance between the actual resonant currents through capacitors Cres1 and Cres2, then I Cres1 (t) = - I Cres2 (t), and considering I Cres1 (t) = I Res (t), it can be concluded that Is1 (t) = 2 * I Res (t). In this example, the following equation is valid in phase #3:

[0117] -N1*Ires(t)-N1*Ires(t)=N2*Is1(t)-N2*Is2(t)

[0118] It can be written as:

[0119] Is2(t)=[(2*N1) / N2+2]*Ires(t), such as Figure 4 shown.

[0120] The converter includes two separate resonant tank circuits. In this example, there are two resonant frequencies based on the actual values of Cres1 and Cres2. For example, Cres1 faces a resonant current where the resonant switch is defined by Fres1 = 1 / (2*pi*sqrt(Cres1*Lk)), where Lk is the leakage of the multi-tap autotransformer.

[0121] At the same time, Cres2 faces the resonant current, where the resonant switch is defined by Fres2 = 1 / (2*pi*sqrt(Cres2*Lk)), where Lk is the leakage of the multi-tap autotransformer.

[0122] Figure 8 is an example graph illustrating dead time or deactivation of all switches in a switched capacitor converter and a voltage converter according to embodiments herein.

[0123] Between time T3 and time T4, the controller 140 turns off switches Q2, Q4, and Q6, and the parasitic capacitance of switch Q4 is charged to Vin / 2+Vout*N1 / N2, switch Q2 is charged at the input voltage Vin, Q6 is charged to 2*Vout, and the parasitic capacitance of switches Q1, Q3, and Q5 is discharged to zero.

[0124] When the capacitance of switches Q1, Q3, and Q5 is discharged to zero, their respective body diodes begin to conduct, enabling ZVS to turn on. The current that enables ZVS is Izvs(t3), which corresponds to -IL(zvs,pk). Therefore, IL(zvs,pk) is a good indicator of when the ZVS condition is achieved for all switches.

[0125] At t= T4 , the switches Q1 , Q3 , and Q5 are turned on in ZVS and ZCS (zero current switching), thereby ending the switching period (ie, time T0 to time T4 ).

[0126] As emphasized in the operation of the power supply 100 in different phases ( Figures 5 to 8 ), the Power Supply 100 converter achieves ZVS conditions under all load conditions regardless of component tolerances.

[0127] In one embodiment, if the expected ZVS condition is designed for the worst case (Vin=V(in,min) and Lzvs+tolerance(Lzvs)), the converter described herein can achieve soft switching operation under all input voltage and load conditions, which makes the embodiments herein suitable for mass production. Moreover, as previously reported, the multi-tap autotransformer of the voltage converter 135 described herein can be implemented using a multi-tap matrix (also known as MMTA), resulting in reduced losses in the windings and core.

[0128] Figure 9 is an example diagram illustrating details of a multi-tap autotransformer according to embodiments herein.

[0129] In the voltage converter 135 ( Figure 2 ) is high efficiency and high power density, thereby enabling the use of lower voltage rated MOSFETs (such as for switches Q1-Q6) compared to a classic LLC converter, and thereby enabling the option of implementing Class II ceramic capacitors (such as for Cres1 and Cres2), which inherently provide high capacitance density.

[0130] Furthermore, as previously discussed, the additional inductor Lzvs (alternatively implemented via the magnetizing inductance of a multi-tap autotransformer) provides inductive energy to ensure ZVS transition of all switches (such as MOSFETs) in the voltage converter 135 .

[0131] In addition to these benefits, another benefit of the multi-tap autotransformer 160 is that it reduces inherent winding losses compared to a classic LLC converter; it reduces the total conduction stress of all FETs (such as switches Q1-Q6), thereby providing more reliable power.

[0132] like Figure 2 and Figure 9 As shown, an example of the proposed multi-tap autotransformer 160 includes four windings. All windings are arranged in series, starting from the terminal node in1 (node a) and ending at the terminal node in2 (node h). More specifically, the primary winding 161-1 (between nodes a and b), the secondary winding 162-1 (between nodes c and d), the secondary winding 162-2 (between nodes e and f), and the primary winding 161-2 (between nodes g and h) are connected in series between nodes in1 and in2. The multi-tap autotransformer 160 includes a node in1, a tap node ph1, a tap node com, a tap node ph2, and a so-called tap at node in2.

[0133] The following discussion provides further understanding associated with the magnetic structure of embodiments of the multi-tap autotransformer 160 .

[0134] More specifically, in Figure 9 In this example embodiment, the four windings of the multi-tap autotransformer 161 are wound on or around a common magnetic core 910, thereby forming a multi-tap autotransformer. As previously discussed, the windings of the multi-tap autotransformer 160 include: i) a first winding group (any suitable number of windings) formed by the primary windings between nodes in1 and ph1 and between nodes in2 and ph2; ii) a second winding group (any suitable number of windings) including, for example, the secondary winding 162-1 and the secondary winding 162-2 between nodes PH1 and PH2.

[0135] Based on this assumption and if we consider an ideal multi-tap autotransformer, and considering that the magnetomotive force (MMF) is established on the secondary side by Is1 (also known as Iph1) and Is2 (also known as Iph2), it must be offset by the MMF in the primary side established by Iin1 and Iin2. In this scenario, the following equation is always valid:

[0136] N1*Iin1+N1*Iin2=N2*iph1+N2*iph2

[0137] Figure 10 is an example diagram illustrating details of a multi-tap autotransformer according to embodiments herein.

[0138] In order to further improve the performance of the proposed converter 135, Figure 2 The multi-tap autotransformer 160 can be used as Figure 10 The enhanced multi-tap autotransformer 160-10 is shown as a replacement.

[0139] exist Figure 10 In this exemplary embodiment, multi-tap autotransformer 160-10 is a multi-tap matrix autotransformer comprising two interconnected elements. It should be noted that the number of interconnected winding elements may vary depending on the embodiment. For example, multi-tap autotransformer 160 described herein may include any number of primary windings connected in series; and multi-tap autotransformer 160 may include any number of secondary windings connected in parallel.

[0140] exist Figure 10In this example embodiment, the multi-tap matrix autotransformer 160-10 includes: i) multiple (two) primary windings 161-11 and 161-12 (each winding has N1 turns), which are connected in series between nodes a and b; ii) multiple secondary windings 162-11 and 162-12 (each winding has N2 turns), which are connected in parallel between nodes c and d; iii) multiple secondary windings 162-21 and 162-22 (each winding has N2 turns), which are connected in parallel between nodes e and f; iv) multiple primary windings 161-21 and 161-22 (each winding has N1 turns), which are connected in series between nodes g and h.

[0141] As previously discussed, the actual ratio between the input and output voltages depends on the ratio between the windings N1 and N2 and the number of windings connected in series or in parallel. Figure 10 When the multi-tap autotransformer 160-10 is used, the ratio between the input voltage Vin and the output voltage Vout is given by the following equation:

[0142] Vin / Vout=4+2*(2N1) / N2

[0143] Figure 11 is an example diagram illustrating details of a multi-tap matrix autotransformer according to embodiments herein.

[0144] In order to further improve the performance of the proposed converter 135, a multi-tap autotransformer 160 may be used as shown in FIG. Figure 11 The enhanced multi-tap autotransformer 160-11 is shown as a replacement.

[0145] like Figure 11 As shown, the number of primary windings and secondary windings in the multi-tap autotransformer 160-11 may vary depending on the embodiment. Figure 10 In the above case, there are M=2 primary windings and secondary windings.

[0146] It should also be noted that the multi-tap autotransformer 160 implemented in the power supply 100 as described herein may include any number M (any integer value, such as M=2, M=3, M=4, etc.) of primary windings (connected in series) and M (any integer value, such as M=2, M=3, M=4, etc.) of second windings (connected in parallel).

[0147] For example, the multi-tap matrix autotransformer 160-11 includes multiple primary windings (N1M=N12=N11=…=N1), which are coupled in series between node a and node b; multiple secondary windings (N2M=N21=N22=…=N2), which are coupled in parallel between node c and node d; multiple secondary windings (N21, N22,…N2M), which are coupled in parallel between node e and node f; and multiple primary windings (N11, N12,…N1M), which are coupled in series between node g and node h.

[0148] In this case, the ratio between the input voltage Vin and the output voltage Vout is given by the following equation:

[0149] Vin / Vout=4+2(M*N1) / N2

[0150] Where M (such as any integer value 1, 2, 3, 4, 5, 6, etc.) is the number of windings connected in series on the primary side and the number of windings connected in parallel on the secondary side.

[0151] The benefit of using the multi-tap autotransformer 160 described herein in the proposed topology is that it can distribute the current among the secondary windings connected in parallel, thereby reducing the leakage inductance of the secondary loop inductance and reducing the overall winding losses; and, if designed properly, can eliminate flux.

[0152] In one embodiment, X=Y. It should be noted that multi-tap autotransformer 160 can be configured to include X primary windings connected in series between nodes a and b, and X primary windings connected in series between nodes g and h. In the same circuit, transformer 160 can be configured to include X secondary windings connected in parallel between nodes c and d, and X secondary windings connected in parallel between nodes e and f.

[0153] Figure 12 is an example block diagram of a computer system for implementing any of the operations as previously discussed according to embodiments herein.

[0154] Any of the resources discussed herein (such as the controller 140 , the voltage converter 135 , the switched capacitor converter 131 , etc.) may be configured to include computer processor hardware and / or corresponding executable instructions to perform the various operations discussed herein.

[0155] As shown, the computer system 1050 of this example includes an interconnect 1011 that provides coupling of a computer readable storage medium (CRSM) 1012, such as a non-transitory type of medium (which may be any suitable type of hardware storage medium in which digital information may be stored and retrieved), a processor 1013 (computer processor hardware), an I / O interface 1014, and a communication interface 1017.

[0156] I / O interface(s) 1014 support connections to repositories 1080 and input resources 1092 .

[0157] The computer readable storage medium 1012 may be any hardware storage device, such as a memory, optical storage, hard drive, floppy disk, etc. In one embodiment, the computer readable storage medium 1012 stores instructions and / or data.

[0158] As shown, the computer-readable storage medium 1012 may be encoded with the controller application 140 - 1 (eg, including instructions) to perform any of the operations discussed herein.

[0159] During operation of one embodiment, processor 1013 accesses computer-readable storage medium 1012 via use of interconnect 1011 to launch, run, execute, interpret, or otherwise perform instructions in controller application 140-1 stored on computer-readable storage medium 1012. Execution of controller application 140-1 generates controller process 140-2 to perform any of the operations and / or processes discussed herein.

[0160] Those skilled in the art will appreciate that the computer system 1050 may include other processes and / or software and hardware components, such as an operating system that controls allocation and usage of hardware resources to execute the controller application 140 - 1 .

[0161] According to various embodiments, it should be noted that the computer system can reside in any of a variety of types of devices, including, but not limited to, a power supply, a switched capacitor converter, a power converter, a mobile computer, a personal computer system, a wireless device, a wireless access point, a base station, a telephone device, a desktop computer, a laptop computer, a notebook computer, a mainframe computer system, a handheld computer, a workstation, a network computer, an application server, a storage device, a consumer electronic device (such as a camera), a camcorder, a set-top box, a mobile device, a video game console, a handheld video game device, a peripheral device (such as a switch), a modem, a router, a set-top box, a content management device, a handheld remote control device, any type of computing or electronic device, etc. The computer system 1050 can reside in any location or be included in any suitable resource in any network environment to implement the functionality as discussed herein.

[0162] Now, through Figure 13 The flowcharts in the following discuss the functions supported by different resources. It should be noted that the steps in the following flowcharts can be performed in any suitable order.

[0163] Figure 13 is a flowchart 1300 illustrating an example method according to embodiments herein. It should be noted that there may be some conceptual overlap with that discussed above.

[0164] In process operation 1310 , the voltage converter 135 receives energy from an input voltage source Vin.

[0165] In process operation 1320, the controller 140 controllably switches the plurality of capacitor circuit paths to transfer energy from the input voltage source Vin to the first primary winding 161-1 and the second primary winding 161-2 of the multi-tap autotransformer 160. As previously discussed, the multi-tap autotransformer 160 transfers energy to the secondary windings of the multi-tap autotransformer in the secondary stage (output stage) 102 of the voltage converter 135.

[0166] In process operation 1330 , the secondary stage 102 of the voltage converter generates an output voltage 123 to power the load 118 via energy received from the multi-tap autotransformer 160 .

[0167] It should also be noted that the techniques herein are well suited for use in power supply applications. However, it should be noted that the embodiments herein are not limited to use in such applications, and the techniques discussed herein are also suitable for other applications.

[0168] Although the present invention has been specifically shown and described with reference to the preferred embodiments of the present invention, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the present application as defined by the appended claims. Such changes are intended to be covered by the scope of the present application. Thus, the foregoing description of the embodiments of the present application is not intended to be restrictive. On the contrary, any limitations to the present invention are set forth in the appended claims.

Claims

1. A power supply comprising: a switched capacitor converter comprising a first flying capacitor and a second flying capacitor; a multi-tap autotransformer comprising a first primary winding and a second primary winding, the first flying capacitor and the second flying capacitor of the switched capacitor converter controllably switched in a circuit path including the first primary winding and the second primary winding; as well as an output stage coupled to receive energy from a combination of the first primary winding and the second primary winding of the multi-tap autotransformer, the output stage operable to generate an output voltage to power a load, wherein the switched capacitor converter comprises a first switch and a second switch connected in series between a voltage source and a first circuit node, and a third switch and a fourth switch connected in series between the voltage source and a second circuit node, wherein the first flying capacitor is connected to a circuit node between the first switch and the second switch, and the second flying capacitor is connected to a circuit node between the third switch and the fourth switch, wherein the first flying capacitor is connected in series with the second primary winding, and the second flying capacitor is connected in series with the first primary winding, and The first primary winding and the second primary winding are connected in series via a secondary winding, such that the first primary winding and the secondary winding are connected at the first circuit node, and the second primary winding and the secondary winding are connected at the second circuit node. 2 . The power supply of claim 1 , wherein the first primary winding, the second primary winding, and the secondary winding are magnetically coupled to each other.

3. The power supply of claim 1, wherein the secondary winding is center-tapped, the output of the secondary winding generating the output voltage in the output stage.

4. The power supply according to claim 1, further comprising: An inductor is connected in parallel with the secondary winding of the multi-tap autotransformer.

5. The power supply of claim 4, wherein the secondary winding is center-tapped, the output of the secondary winding generating the output voltage.

6. The power supply of claim 5, wherein the inductor is operable to provide zero voltage switching of the first, second, third, and fourth switches in the switched capacitor converter.

7. The power supply of claim 1 , further comprising: A controller operable to switch between: i) coupling a first resonant circuit path comprising the first flying capacitor and the second primary winding to an input voltage, and ii) coupling a second resonant circuit path including the second flying capacitor and the first primary winding to the input voltage.

8. A power supply method, comprising: receiving energy from an input voltage source; controllably switching a plurality of capacitor circuit paths in a switched capacitor converter to transfer said energy from said input voltage source to a first primary winding and a second primary winding of a multi-tap autotransformer, said multi-tap autotransformer being operable to transfer said energy to an output stage; as well as At the output stage, an output voltage is generated to supply power to a load via the energy received from the multi-tap autotransformer, wherein the switched capacitor converter comprises: a first switch and a second switch connected in series between a voltage source and a first circuit node; and a third switch and a fourth switch connected in series between the voltage source and a second circuit node; a first flying capacitor connected to a circuit node between the first switch and the second switch; and a second flying capacitor connected to a circuit node between the third switch and the fourth switch, wherein the first flying capacitor is connected in series with the second primary winding of the autotransformer, and the second flying capacitor is connected in series with the first primary winding of the autotransformer, and The first primary winding and the second primary winding are connected in series via a secondary winding, such that the first primary winding and the secondary winding are connected at the first circuit node, and the second primary winding and the secondary winding are connected at the second circuit node.

9. The method of claim 8, wherein controllably switching the plurality of capacitor circuit paths comprises: The output of the multi-tap autotransformer is rectified to generate the output voltage.

10. The method of claim 8, wherein the multi-tap autotransformer includes a center-tapped secondary winding that generates the output voltage.

11. The method according to claim 8, further comprising: Zero voltage switching of the first switch, the second switch, the third switch, and the fourth switch in the switched capacitor converter is provided via an inductor.

12. The method of claim 8, wherein the plurality of capacitor circuit paths comprises: i) a first resonant circuit path comprising a combination of a first capacitor and the first primary winding; and ii) a second resonant circuit path comprising a combination of a second capacitor and the second primary winding; as well as wherein controllably switching the plurality of capacitor circuit paths comprises: switching between: i) coupling the first resonant circuit path to an input voltage; and ii) coupling the second resonant circuit path to the input voltage.

13. The method of claim 8, wherein generating the output voltage to power the load comprises: The output of the multi-tap autotransformer is converted into the output voltage.

14. Computer-readable storage hardware having instructions stored thereon, said instructions, when executed by computer processor hardware, causing said computer processor hardware to: controllably switching a plurality of capacitor circuit paths in a switched capacitor converter to transfer energy from an input voltage source to a first primary winding and a second primary winding of a multi-tap autotransformer operable to transfer the energy to an output stage of a voltage converter; as well as At the output stage, an output voltage is generated to supply power to a load via the energy received from the multi-tap autotransformer, wherein the switched capacitor converter comprises: a first switch and a second switch connected in series between a voltage source and a first circuit node; and a third switch and a fourth switch connected in series between the voltage source and a second circuit node; a first flying capacitor connected to a circuit node between the first switch and the second switch; and a second flying capacitor connected to a circuit node between the third switch and the fourth switch, wherein the first flying capacitor is connected in series with the second primary winding of the autotransformer, and the second flying capacitor is connected in series with the first primary winding of the autotransformer, and The first primary winding and the second primary winding are connected in series via a secondary winding, such that the first primary winding and the secondary winding are connected at the first circuit node, and the second primary winding and the secondary winding are connected at the second circuit node.

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