Self-commutated dc-dc converter with switching connections and reconfigurable elements enabling switching

Abstract

Systems and apparatus for enabling efficient energy harvesting are disclosed. A power conversion apparatus includes at least first and second inductors, a rectifier, a load, and at least first and second energy storage capacitors. The first inductor is galvanically isolated from the second inductor, and each of the first inductor and the second inductor is an output inductor of the power conversion device, and the rectifier is configured to charge at least the first energy storage capacitor and the second energy storage capacitor. Each of the at least first energy storage capacitor and the second energy storage capacitor is coupled to a load, and an interconnection of the at least first energy storage capacitor and the second energy storage capacitor is switched between at least one of an electrical series connection to an electrical parallel connection and an electrical parallel connection to an electrical series connection.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of two U.S. provisional applications, namely, U.S. provisional application serial number 63 / 478,403, entitled “RECONFIGURABLE ELEMENT FOR ENERGY HARVESTING,” and U.S. provisional application serial number 63 / 520,966, entitled “IMPROVED SWITCHING POWER CONVERTER.” The contents of U.S. provisional application serial number 63 / 478,403 and U.S. provisional application serial number 63 / 520,966 are incorporated herein by reference in their entireties. Technical Field

[0003] The subject matter described herein generally relates to enabling efficient energy harvesting. Background Art

[0004] Energy harvesting has been used with a number of devices of various shapes, sizes, and capabilities. In particular, energy harvesting has been used in association with sensors and controls that are mobile, operate without batteries, and have the ability to perform wireless communications. For example, improvements have been made related to devices that operate in a continuous low-power operating mode with intermittent power drawn from a quasi-continuous power source. These power sources are associated with lower wattage and voltage. Advances and improvements have been made with respect to the collection and transmission of information related to transient conditions (e.g., conditions that occur after a switching action). Note that, in contrast to steady-state conditions, transient conditions can occur in time periods ranging from microseconds to hundreds of milliseconds and depend on various circuit parameters such as resistance, inductance, capacitance, etc. The amplitude of the transient voltage fluctuates until a steady-state condition is achieved.

[0005] However, some challenges associated with transient energy harvesting sources include relatively low resonant frequencies and high source impedances. One challenge is that there can be relatively deep and wide losses of the available power generated by the transient energy harvesting source due to the multiple zero crossings of the resonant waveform on a specific time scale that is larger than the time scale of filtering by standard capacitive storage methods.

[0006] Therefore, transient energy harvesting devices and systems that address and overcome the above-mentioned deficiencies would be desirable. Summary of the Invention

[0007] Aspects and examples described in this disclosure address and overcome the aforementioned challenges of current transient energy harvesting devices and systems. In particular, aspects and examples of this disclosure describe a technique that improves energy transfer efficiency during transient conditions by varying the characteristics of an inductive source and a capacitive load within a specific time frame to optimize the voltage ratio.

[0008] This article describes systems and devices for optimizing voltage ratios and improving energy transfer efficiency. Furthermore, this article describes systems and devices related to DC-DC converters that facilitate commutation of recovered energy to an array of storage capacitors, regardless of their connection state, and enable more consistent current flow across source impedances. Related devices and techniques are also described.

[0009] In one aspect, a power conversion device may include at least a first inductor and a second inductor, a rectifier, a load, and at least a first energy storage / bulk capacitor and a second energy storage / bulk capacitor. In some aspects, the first inductor may be galvanically isolated from the second inductor, and each of the first inductor and the second inductor may be an output inductor of the power conversion device. In some aspects, the rectifier may be configured to charge at least the first energy storage capacitor and the second energy storage capacitor, and each of at least the first energy storage capacitor and the second energy storage capacitor may be coupled to the load, and the interconnection of at least the first energy storage capacitor and the second energy storage capacitor may be switched between at least one of an electrical series connection to an electrical parallel connection and an electrical parallel connection to an electrical series connection. In various aspects, the power conversion device may further include a third inductor, wherein the third inductor may be an input inductor galvanically isolated from at least the first inductor and the second inductor, and may be coupled to at least the first inductor and the second inductor via an isolation functional coupling.

[0010] In some aspects, the power conversion device of Example 1 may further include a third inductor and a fourth inductor, wherein each of the third inductor and the fourth inductor may be an input inductor. In some aspects, each of at least the first inductor and the second inductor may be galvanically isolated from each of the third inductor and the fourth inductor, and at least the first inductor may be galvanically isolated from at least the second inductor. In some aspects, each of the first inductor and the second inductor may be coupled to at least one of the third inductor and the fourth inductor via a magnetic field-based connection. Alternatively, in some aspects, each of at least the first inductor and the second inductor may be coupled to at least one of the third inductor and the fourth inductor via a capacitive connection. In some aspects, the power conversion device may include an input source. In some aspects, each of at least the first inductor and the second inductor is coupled to an input source, and the coupling to the input source is switched in an alternating manner so that only one input inductor is connected to the input source at a time. In some aspects, the power conversion device may also include multiple switching input inductors, wherein each of the multiple switching input inductors can be coupled to a corresponding output inductor via an isolation function coupling, and each of at least the first inductor and the second inductor can be coupled to a corresponding energy storage capacitor via a rectifying element.

[0011] In another aspect, a system may include at least two output inductors, a rectifier, a plurality of switches, at least two energy storage capacitors, and a load. In some aspects, each of the at least two output inductors may be coupled to one of the at least two energy storage capacitors via a rectifier, and the plurality of switches may be operable to commutate the at least two energy storage capacitors to the output in an electrical series connection or an electrical parallel connection. In various aspects, the system may be based on a DC-DC converter.

[0012] In another aspect, a device includes a plurality of windings magnetically coupled to an energy source. In various aspects, each of the plurality of windings can have a characteristic and a plurality of switches, where the characteristic can correspond to inductance, current, or stored energy. In various aspects, each of the plurality of switches can be communicatively coupled to the windings to place the windings in a plurality of combinations of series and parallel connections. In some aspects, control logic can operate the plurality of switches to control the plurality of windings. In some aspects, the characteristic can be uniform across the plurality of windings, the plurality of windings can include two windings, and the plurality of switches can include three switches, the three switches being configurable to place the plurality of windings in a series configuration and a parallel configuration relative to a load.

[0013] In some aspects, the plurality of windings may include four windings, and the plurality of switches may include nine switches for configuring the plurality of windings and the plurality of switches in a 4-series, 4-parallel, and 2×2 configuration relative to the load. In some aspects, the plurality of windings may include two windings, and the plurality of switches may include seven switches for providing series and parallel connection states of the windings and a positive or negative connection of the plurality of windings relative to the load. In some aspects, at least one of the plurality of switches may be modulated to control power to the load.

[0014] On the other hand, a system may include multiple capacitors, multiple switches, and control logic. In various aspects, each of the multiple capacitors may have a characteristic corresponding to capacitance, voltage, or stored energy. In various aspects, each of the multiple switches may be communicatively coupled to the multiple capacitors so as to place the multiple capacitors in multiple combinations of series and parallel connections. In various aspects, the control logic may operate the multiple switches to control the connection of the multiple capacitors. In some aspects, the characteristic may be uniform for the multiple capacitors. In various aspects, each of the multiple capacitors may include two capacitors, and the multiple switches may provide series and parallel connection states of the multiple capacitors to the source. In various aspects, the multiple capacitors may include four capacitors, and the multiple switches may include nine switches. In various aspects, the capacitors and switches may be configured in 4 series, 4 parallel, and 2×2 configurations.

[0015] In another aspect, a system includes a plurality of capacitors and three switches, and the plurality of capacitors can be electrically coupled in a subcircuit based on multiple recursive stages. In some aspects, the first stage can include a subset of the plurality of capacitors and three switches, and the three switches can be operable to change the connection of the subset of the plurality of capacitors from a series connection to a parallel connection and vice versa. In some aspects, the system can also include a plurality of galvanically isolated output inductors. In some aspects, each of the plurality of galvanically isolated output inductors can be coupled to a corresponding one of the plurality of capacitors using a rectifying component. In some aspects, the system can also include at least one input inductor. In some aspects, the plurality of galvanically isolated output inductors can be coupled to the at least one input inductor via an isolated functional coupling connection.

[0016] In yet another aspect, a system includes a plurality of capacitors, a rectifier, a controller, and a plurality of switches. In various aspects, the plurality of switches can be operably connected to the plurality of capacitors, and the controller can be operated to control each of the plurality of switches to change the connection state of the plurality of capacitors from a series configuration to a parallel configuration, and from a parallel configuration to a series configuration. In some aspects, the system can also include a plurality of galvanically isolated output inductors. In some aspects, each of the plurality of galvanically isolated output inductors can be coupled to a corresponding one of the plurality of capacitors via a rectifier. In some aspects, the system can also include at least one input inductor. In some aspects, the plurality of galvanically isolated output inductors can be coupled to the at least one input inductor via an isolated functional coupling connection.

[0017] Details regarding various aspects and examples based on varying characteristics of inductive sources and capacitive loads are provided in greater detail throughout this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate certain aspects of the subject matter disclosed herein and, together with the description, help explain some of the principles associated with the disclosed embodiments.

[0019] Figure 1 depicts an example graphical representation of the rectified output of a damped sinusoidal output inductive energy harvester according to some aspects described and illustrated herein;

[0020] Figure 2 depicts an example graphical representation of power values ​​dissipated from a damping source in a resistive load according to some aspects described and illustrated herein;

[0021] Figure 3 depicts an example graphical representation depicting energy stored in an energy storage capacitor according to some aspects described and illustrated herein;

[0022] Figure 4 depicts an example circuit representation of components included as part of an improved energy harvester of the present disclosure according to some aspects described and illustrated herein;

[0023] Figure 5 shows an example circuit having two identical rectifier blocks according to some aspects described and illustrated herein;

[0024] Figure 6 An example circuit is shown having winding feed connectors such that a first winding connects A and B and a second winding connects C and D according to some aspects described and illustrated herein;

[0025] Figure 7shows a number of circuit arrangements capable of connecting capacitors in series and in parallel according to some aspects described and illustrated herein;

[0026] Figure 8 A high-level circuit is shown that is recursively configured according to some aspects described and illustrated herein, wherein Figure 7 The two capacitors shown are replaced with lower value capacitors and a set of six switches;

[0027] Figure 9 depicts example graphical representations of normalized capacitance values ​​across a fully parallel configuration for various array sizes in accordance with some aspects described and illustrated herein;

[0028] Figure 10 Depicts example circuit configurations according to some aspects described and illustrated herein, wherein multiple energy harvesting windings can be combined in various configurations via switching elements to provide an optimal voltage range to a DC-DC converter;

[0029] Figure 10 Further illustrated is the DC-DC converter for charging a switched array of capacitors according to other aspects described and illustrated herein;

[0030] Figure 11 depicts example graphical representations according to some aspects described and illustrated herein that include voltage characteristics of various conventional devices relative to voltage characteristics of devices utilizing a capacitor matrix or capacitor configuration as described in the present disclosure;

[0031] Figure 12 shows a conventional circuit configuration including a single-phase SEPIC DC-DC converter charging an array of four capacitors configured according to aspects described herein;

[0032] Figure 13 A SEPIC DC-DC converter with multiple outputs is shown, wherein each capacitor of a switchable capacitor array can be electrically connected to a specific output coil and rectifier diode according to some aspects described and illustrated herein;

[0033] Figure 14 A multiple-input, multiple-output circuit configuration is shown according to some aspects described and illustrated herein, wherein the charging source for each capacitor is energized sequentially from the input terminal, and each capacitor has a specific output coil and diode;

[0034] Figure 15 shows a circuit configuration based on a single input with two galvanically separated output loops, for example, at least before interconnection through a switch matrix, according to some aspects described and illustrated herein;

[0035] Figure 16A circuit configuration is shown according to some aspects described and illustrated herein, wherein two input inductors, which may be galvanically isolated from two output inductors but coupled via mutual inductive and capacitive coupling elements, are sequentially operated using separate switching phases, and the output inductors may be configured to charge a storage capacitor via a rectifier;

[0036] Figure 17 illustrates a circuit configuration according to some aspects described and illustrated herein in which an input voltage can be sampled through a resistor to generate a reference current for voltage-dependent current limiting;

[0037] Figure 18 shows an example graphical representation representing a baseline level of energy extraction efficiency according to some aspects described and illustrated herein;

[0038] Figure 19 illustrates an example graphical representation showing the level of improvement in energy extraction efficiency associated with a circuit configuration that may have an input controlled current mirror according to some aspects described and illustrated herein;

[0039] Figure 20 shows an example graphical representation representing a baseline level of energy extraction efficiency according to a circuit configuration that does not employ a capacitive switching feature according to some aspects described and illustrated herein; and

[0040] Figure 21 Illustrated are example graphical representations showing improved energy extraction efficiency levels based on the use of capacitive switching features according to some aspects described and illustrated herein. DETAILED DESCRIPTION

[0041] As described above, aspects and examples described in this disclosure relate to a technique for improving the efficiency of energy transfer and regulation during transient conditions by varying the characteristics of an inductive energy source and a capacitive energy storage device within a specific time frame in order to increase the harvested energy that can be utilized by a load device. In various aspects, a load device can be associated with an overvoltage limit, an undervoltage limit, and a suitable operating voltage. In various aspects, a voltage ratio represents a specific undervoltage (V UV ) with respect to the device’s input overvoltage (V OV ), which is expressed as, for example, r = V UV / V OV Broadly speaking, the energy harvesting and power conversion industry is focused on providing continuous power to operate various devices within certain operating limits and within the threshold of a desired operating voltage. However, the technologies implemented by this industry have not adequately addressed improving energy recovery from limited, transient energy sources.

[0042] Non-battery-based systems (e.g., capacitor-based systems) have a nearly linear relationship between the square of the voltage and the stored energy, enabling the storage and delivery of small amounts of energy, i.e., amounts of energy with values ​​between undervoltage and overvoltage values. Furthermore, this linear relationship between the square of the voltage and the stored energy results in an amount of unused stored energy, as it is associated with the capacitor voltage being below the undervoltage limit of the load device. In various aspects, energy recovered from a finite source is stored in a storage capacitor and input into a regulator. The finite source operates to increase or decrease the capacitor voltage between a specific overvoltage threshold level and a specific undervoltage threshold level. However, in various aspects, the storage capacitor cannot be charged above a specific input overvoltage value, such as 5.4 volts (V), at the point of regulator use. Furthermore, if the value of the storage capacitor discharged falls below the undervoltage lockout voltage of 1.8V, the regulator cannot provide the desired output voltage. In various aspects, if the variable r has a value of 1 / 3, a capacitor fully charged to 5.4V and then discharged to the load may have a value of r2 of 1 / 9 of the specific residual charge. In various aspects, this unused energy may be lost due to leakage current before the capacitor is recharged. Certain characteristics of the capacitor (e.g., capacitor nonlinearity, capacitance-to-voltage curve, etc.) further reduce the energy available to the load during the charge and discharge cycles. In various aspects, even if the regulator operates at 100% efficiency, a fully charged capacitor with a capacity of 5.4V can only be drained to 1.8V, leaving approximately 11% of the harvested energy on the storage capacitor unused. In various aspects, certain circuit configurations of the present disclosure utilize a portion of this approximately 11% unused energy by changing the connection state of the circuit (e.g., from a series circuit connection to a parallel circuit connection), thereby enabling the recovery of approximately 75% of the unused energy and reducing the total loss to approximately 3%.

[0043] In various aspects, another circuit configuration is described herein that relates to an improved version of a DC-DC converter in which the current in the source impedance can be maintained at a more constant value. Furthermore, the improved version of the converter commutates recovered energy to an array of storage capacitors regardless of their connection state (e.g., whether the capacitors are connected in series or in parallel), thereby improving the overall output commutation circuit.

[0044] Figure 1An example graphical representation 100 of a damped sinusoidal output of an inductive energy harvester with ideal rectification is depicted. As shown in the example graphical representation 100, the x-axis corresponds to time values ​​102, and the y-axis corresponds to voltage values ​​104. The example graphical representation 100 can be associated with a 25 Hz mechanical energy source that can be obtained by an inductive pick-up. Such a mechanical energy source can have a nominal inductance of 100 mH (15.7 ohms reactance at 25 Hz) and a source resistance of 100 ohms. Furthermore, the rectified energy can be represented as a pulsed half-sine wave having a period of 20 milliseconds (ms) and an open circuit voltage of 9 V at a first peak 106.

[0045] In various aspects, techniques that may be implemented may include charging a capacitor with a decaying voltage, as shown in example graphical representation 100, thereby enabling energy storage for the future. However, as the capacitor charges, the voltage across the capacitor can increase, and as such, the decaying waveform may not be able to passively push charge into the capacitor beyond a certain threshold. While using a capacitor with greater capacitance can mitigate this issue, the greater capacitance of the capacitor may present a lower impedance at a given frequency. Additionally, losses due to the source resistance may increase based on the square of this current, while the charging rate only increases linearly. This can result in significant losses, for example, during device startup. Such losses may not be consequential for devices functioning in continuous operation, but for operations performed using transient energy harvesting sources, such losses can be significant and may disrupt or prevent the operation of various device functions.

[0046] Note that applying a harvester to a load can be operative to cause losses in the winding. Applying a harvester to a load also serves to shorten the window of time during which energy is available. For a continuous energy source with low reactance relative to the winding resistance, the load is equal to the winding resistance (e.g., given by the expression R LOAD =R WINDING denoted as , a specific power value and a specific energy transfer are both achieved. However, for a finite energy source, removing energy under certain power transfer conditions (e.g., high power transfer conditions) may not provide suitable energy transfer (e.g., high energy transfer). For example, in various aspects, a load resistance equal to approximately 1.5 times the parasitic winding resistance may operate to improve energy recovery. Furthermore, any deviation from the expected 1:1 matched load required for suitable power transfer (e.g., high or maximum power transfer) can be explained by a reduced power transfer duration due to limited energy. The higher the value of the load resistance during the duration of the damped sinusoidal waveform, the greater the reduction in the power transfer rate, with a suitable or desired range being approximately between 1.5 and 1.

[0047] Figure 2An example graphical representation 200 depicts the amount of power dissipated in a resistive load from a damping source. The graphical representation 200 represents the maximum energy value that can be extracted during a particular transient event, for example, by integrating the area under the curve. With respect to the example graphical representation 200, an upper limit of 4.3 millijoules (mJ) of energy can be applied to a resistive load by an ideal rectifier. A practical rectifier may have losses and yield approximately 3.4 to 4 mJ of energy.

[0048] Figure 3 An example graphical representation 300 is depicted depicting energy stored in a storage capacitor. The example graphical representation 300 includes an x-axis corresponding to time values ​​302 and a y-axis corresponding to voltage values ​​304. Note that the energy stored in the storage capacitor is limited by the falling source voltage relative to the rising capacitor voltage. It should be noted that, unlike the above-described techniques (i.e., Figures 1 to 3 A particular problem associated with the technique described in the accompanying drawings (corresponding to the diagrams depicted in FIG) is that there may be a mismatch between the inductive source voltage distribution, the capacitive load distribution, and the parasitic resistance. In various aspects, the source voltage may decrease as the load voltage increases, resulting in a significant portion of the source energy being unrecoverable. Furthermore, when the source voltage is high and the capacitor voltage is low, a large current may flow through the device (e.g., a device including a capacitor and a buck-boost regulator). As a result, power may be dissipated in the parasitic resistance, which in turn may result in inefficient energy extraction from the mechanical resonator.

[0049] In various aspects, the use of a buck-boost or single-ended primary inductor converter ("SEPIC") (a type of DC-DC converter) or AC-to-DC converter provides improved efficiency. However, these devices also have various disadvantages. For example, these converters provide efficiencies exceeding 90% for steady-state operation near a suitable voltage ratio of input to output. However, the 90% efficiency drops significantly for values ​​above and below this ratio. In particular, the efficiency values ​​are negligible (e.g., approaching values ​​of approximately 0) below the undervoltage lockout of the DC-DC controller. In various aspects, while the use of piezoelectric transducers having a relatively high resonant frequency, a relatively short zero width, and a wide range of voltages also helps to alleviate some of the above-mentioned problems, the use of piezoelectric transducers is only a partial solution. The above-mentioned techniques can produce signals with an initial rise time and a long decay from the maximum voltage to the zero value. As such, all of the above-mentioned techniques are, at best, partial and imperfect solutions.

[0050] Figure 4 An exemplary circuit representation 400 of components included as part of the improved energy harvester of the present disclosure is depicted. In various aspects, it should be noted that in most inductive sources, the output voltage and parasitic resistance can be proportional to or matched to the winding inductance. In various aspects, by using multiple windings (represented by the term "N"), each winding has a 1 / Nth By adjusting the inductance and resistance of the windings, the connection of the windings can be switched or modified from a series configuration to a parallel configuration, and vice versa, particularly when the voltage exceeds or falls below a certain set of thresholds. The manner of operating the circuit can be used to maintain the winding voltage within the operating range of the DC-DC converter for a greater proportion of the waveform and to maintain the voltage closer to the desired voltage.

[0051] Additionally, to avoid high currents during switching operations, each element of the circuit corresponding to example circuit representation 400 can be designed to have the same stored energy and inductance. series ×J parallel There are N elements in an arrangement or configuration such that I and J are factors of N, and I / J is a numerical rating representing the degree of connectivity of a series circuit. In various aspects, if the element inductance is Lo, the array inductance is ILo / J, and connectivity serves as a scaling ratio of the inductance at a constant stored energy. In various aspects, circuit losses due to the relatively slow FET switches interrupting the current in the inductor are advantageous in commutating the switches at voltage peaks. Such voltage peaks can be represented by "V = Ldi / dt". The value of "V" is maximum when the stored energy of the inductive element is zero. In various aspects, the fast switches can also operate to efficiently commutate the current while maintaining switching losses at a small value, which is advantageous because it reduces instances of voltage variations.

[0052] In various aspects, such a parallel connection can reduce the voltage range from the rectifier, as a series combination can provide higher voltage at lower load currents, while a parallel combination can allow higher currents when the load voltage is low. Note that a parallel combination can be used when the voltage of a single winding is high, and a series combination can be used when the voltage of a single winding is low. In this way, the voltage range can be reduced. Because the two inductors have continuity in I and dI / dt through fast switching events, the transition resistance and duration of the switching losses can be maintained. In various aspects, additional details of the circuit configuration as described in the present disclosure are provided in the following paragraphs.

[0053] In one aspect, the circuit configuration can be implemented to include two windings with connectivity states corresponding to 2Lo and 0.5Lo. In addition, the circuit configuration can include a p-channel FET with a high-side switch that closes for series connection and opens for parallel connection, while additional 4 p-channel field effect transistors ("FETs") and 4 n-channel FETs form a commutated bridge rectifier. Although the example circuit ignores the potential backflow of current from the load, this can be addressed by controlling one or more comparators of the p-channel FETs. In various aspects, if the series connection switch is open, the parallel enablement of the FET pair completes the parallel connection. A third Lo state can be obtained by disabling one of the two windings and extracting energy from only one of the two coupled winding inductors. Alternatively, in various aspects, if the lower R ds Or if the drain on-resistance exceeds the losses in the charge pump, a charge pump gate driver and an n-channel FET can be used.

[0054] In various aspects, in operation, by connecting a particularly high value resistor between the positive terminals of the two windings and another resistor between the negative terminals of the two windings, the potential relative to the positive terminals of the two windings and the negative terminals of the windings can be established. In addition, commutation and rectification can be achieved using 8 Schottky diodes and p-channel FET series switches. In various aspects, in the series connection, the FETs in the on state can overrule the resistors with a small loss of conductor current. In addition, the diodes in the inner windings can never be forward biased in this state. In various aspects, when the FETs are in the off position, the resistors can cause the winding terminal potentials to track and all appropriate diodes to conduct. In various aspects, the combination of diodes in parallel with the comparator-driven FETs provides the desired efficiency and early onset of useful power.

[0055] In various aspects, the implementation of the winding switches can be further simplified. In particular, in various aspects, the simplification can involve individual rectification of the windings so that the polarity of the windings is identified and known. However, this situation results in doubling the rectification losses of the series combination in the circuit, which in turn negates the desired result of increasing the output voltage relative to the diode voltage drop or the MOSFET conduction voltage. In various aspects, the windings are individually rectified so that the polarity is known. In this case, the rectification losses of the series combination may increase (e.g., double). In various aspects, if a MOSFET bridge is utilized, the losses in the bridge rectifier can be reduced. In various aspects, it should be noted that reverse current can be avoided. In this case, an active bridge control can be used to control the FET state.

[0056] Figure 5Such an example circuit 500 is shown with two identical rectifier blocks 510 and 520. In various aspects, closing FET Q5 531 while opening FETs Q6 532 and Q7 533 creates a series combination. Conversely, flipping the FET states creates a parallel combination. This approach allows for a 2-phase rectifier with m+1 states. m Recursive DC commutation of an array of windings.

[0057] In various aspects, the two windings may be AC ​​commutated in series or parallel, and the array may be rectified. Figure 6 Such a circuit 600 is shown with winding feed connectors 610 such that the first winding connects A and B and the second winding connects C and D. The FETs in the series connected closed commutation circuit 620 and the FETs in the parallel commutation 630 are open. The parallel state is obtained by reversing the FET states. This method allows a 2-phase circuit with m+1 states. m The AC commutation of an array of windings is recursive. In this example, each simplified FET in the illustrated series commutation circuit 620 and parallel commutation circuit 630 requires at least a back-to-back FET to commutate the AC waveform. In addition, separate gate drivers may be required for P- and N-FET operation over the entire AC voltage range.

[0058] In other aspects, a configuration with four windings can be utilized. For example, the configuration can include an arrangement of 1×4, 2×2, or 4×1 windings that provide three states. Alternatively, if some windings are disconnected, five states can be provided. In various aspects, using twelve windings can enable the creation of the following states: 1×12, 2×6, 3×4, 4×3, 6×2, and 12×1. Based on the numerical ordering of the number of series elements divided by the number of parallel elements, the progression across the various states can be characterized as less series to more series. In various aspects, the upper limit of the number of windings and the number of states may be limited by the reproducibility of the winding inductance and the mutual coupling across the winding set, as well as the switching implementation and losses relative to the improved efficiency of the system. On the other hand, a single matching set of windings consisting of N wires can be used to create N nearly identical windings. And, on the other hand, bifilar windings can be used for a dual-winding system with nearly identical inductance and high mutual coupling.

[0059] In various aspects, by starting at zero volts in the series combination, a specific forward voltage (e.g., a minimum forward voltage) can be quickly met in the rectifier and subsequent stages. Furthermore, the control logic can bootstrap or operate from this rapid rise in voltage. In other words, the control logic, implemented and accessed using a microcontroller, such as a chip installed in the device, can start (start) and operate from this rapid rise in voltage. As higher currents become necessary, the high source resistance of the series connection may be undesirable. Furthermore, the voltage of the series connection may not be desirable for proper operation or may exceed the ratings of the relevant components. In various aspects, an arrangement with fewer series connections can reduce voltage and allow current to be drawn more efficiently from a lower impedance source. In various aspects, when the waveform of an individual winding reaches a peak and then decreases, the voltage may drop to a level that is no longer optimal for subsequent stages. At this point, a more series arrangement can provide a higher level of efficiency. In some aspects, even a fixed connectivity time sequence may be desirable. In some aspects, a state machine or microprocessor program can be operated to track the ideal operating point.

[0060] In various aspects, arrays of capacitive sources, such as arrays of piezoelectric elements, may also be commutated using similar circuits, where the winding inductors may be replaced by piezoelectric capacitors.

[0061] The same principles discussed above for commutating the source array can be applied to the storage capacitor array. In various aspects, if the load capacitance values ​​are split or separated in a similar manner, initial charging can be achieved at relatively low current values, or a faster voltage rise can be achieved at a given current value by using a series combination of capacitors. However, it should be further noted that the later stages of charging can occur in parallel at a lower voltage, which can allow the load voltage presented by the capacitors to approximately match the source voltage provided by the windings, for example, over a large portion of the waveform. In this way, direct passive charging can be improved.

[0062] An example method of arranging switches for a capacitor array uses recursive parallel and / or series switching with N=2m+1 capacitors, where m is the recursive number and m=0 is a single capacitor. This recursive control provides for the array capacitance relative to the element capacitance 2 -m , 2 2-m ,…2 m-2 , 2 m The array has m+1 states and lacks the finer resolution of more complex commutation structures of switches. However, it allows the operating voltage of the charge array to be controlled within a roughly 2:1 voltage range over a charge range that is m times wider than a single capacitor. Such an array can feed a DC-DC converter more efficiently than a single fixed capacitor.

[0063] Figure 7Multiple circuit arrangements are shown that can connect capacitors in series and in parallel according to one or more aspects described and illustrated herein. Circuit 700 is a storage capacitor, while circuit 702 is a circuit that enables connecting two capacitors in series, and circuit 704 is a circuit that enables connecting two capacitors in parallel. With respect to circuit 702, when first switch 710 and second switch 712 are turned on and third switch 714 is turned off, first capacitor 706 is connected to second capacitor 708. Conversely, in circuit 704, if first switch 710 and second switch 712 are turned off and third switch 714 is turned on, third capacitor 716 and fourth capacitor 718 can be connected in series.

[0064] Figure 8 A recursively configured higher order circuit 800 is shown, where Figure 7 The two capacitors shown are replaced with lower value capacitors and a set of six switches. A higher order circuit (a second order switch matrix) of this recursive configuration has Figure 11 The voltage characteristics of the curves shown and described later in this disclosure.

[0065] Figure 9 An example graphical representation 900 of normalized capacitance values ​​on a fully parallel configuration for various array sizes is depicted. For example, with respect to the example graphical representation 900, there can be two methods that can be used for the purpose of manufacturing a digitally tunable capacitor. In various aspects, an array of ceramic capacitors (e.g., N capacitors) can be printed on a substrate having 2N pads, each of which has a stud bump or other wafer-to-wafer MEMS bonding component. In various aspects, an internal area of ​​the integrated circuit can have matching pads to which the capacitor array can be bonded, and can have external pads that are wire-bonded to the external leads of the package. In other aspects, an array of micro-supercapacitors can be printed directly onto a semiconductor controller, for example, in a monolithic solution.

[0066] In various aspects, it should be noted that the capacitor switching thresholds can be selected based on the ratings of the individual capacitors or the power requirements of subsequent associated circuits. Control logic can be used to divide the array into sub-segments for the purpose of forming an adjustable ratio charge pump. In addition, the control logic can also be operated to monitor the net capacitance of the elements and adjust I / J to maintain a near constant voltage as energy is added to or removed from the system. Furthermore, unlike switched capacitors and charge pumps, charge may not be commutated from one element to another, and the I×J capacitor array will have an IC o / J of capacitance, where the equivalent series resistance is I / J*(ESR cap +R ds_switch ). In short, such an aspect corresponds to a digitally controlled solid-state battery.

[0067] Figure 10 An example circuit configuration 1000 is depicted in which multiple energy harvesting windings 1001 and 1002 can be combined in various configurations via switching elements 1011, 1012, and 1013 to provide an optimal voltage range to a DC-DC converter 1020. In various aspects, such a DC-DC converter can charge a digitally controlled capacitor 1030. In various aspects, a winding configuration control 1040 can be controlled solely by the voltage of the windings. Additionally, in various aspects, a capacitor configuration control 1050 can be controlled solely by the voltage of the capacitors. In other aspects, the control mechanism can be operable such that the ratio V of the DC-DC converter can be controlled. IN / V OUT , thereby improving the operating efficiency of the device. In various aspects, such an example harvester can be input into a second DC / DC regulator with sufficiently fine-tuned capacitors. The capacitors can maintain a constant voltage until their maximum charge, and the windings can be adjusted to optimally feed the capacitors.

[0068] In various aspects, the DC-DC converter may include a buck-boost and SEPIC converter, and / or other similar converters. In other aspects, all winding switching and active rectification may be incorporated into the power converter. In various aspects, once the capacitor is charged, the goal may be to utilize the charged capacitor to supply charge to the circuit. In various aspects, as a non-limiting example, a 330μF capacitor may be charged to 4.92V (4mJ). This charge may then be utilized to supply 25mA of current to a 2V load using a buck-boost converter with an average efficiency of 83.3%. It should be noted that a drain of 60mW may exist on the capacitor. In particular, in various aspects, the capacitor voltage may be allowed to drop through the optimal voltage until it reaches the dropout voltage of the converter. In various aspects, assuming a voltage lower limit of 1V, approximately 0.165mJ of energy may be retained on the capacitor, and the circuit may be powered for a time frame of almost 64ms. On the other hand, the remaining energy on the capacitor may represent an additional 2.75ms of operation. In various aspects, the percentage losses of 16.7% in the converter (668 μJ) may represent another 16.7 ms of operating time during which the circuit may operate with ideal conversion.

[0069] In various aspects, the steady-state and transient efficiency of a particular buck-boost regulator (e.g., represented by the ISL9122A) was evaluated. Using the steady-state efficiency relative to the input voltage from a 4mJ charge on a 330μF capacitor, the buck-boost regulator was able to supply 2.875mJ to the load without switching, which corresponds to an average efficiency level of 71.9%. Additionally, in various aspects, using four 165μF capacitors in a 660μF / 165μF / 21.5μF configuration, the same 4mJ input supplies 3.4mJ to the load without switching, which corresponds to an 18.2% load. This improvement in percentage is achieved due to rearranging the components into more series connections. A brief description of Table 1 provided below is helpful.

[0070] Eo Vin eff dE dEin Eo Vin eff dE dEin 4 4.92366 0.763 0.25 0.327654 4 3.481553 0.829 0.25 0.301568 3.672346 4.717695 0.774 0.25 0.322997 3.698432 3.347741 0.84 0.25 0.297619 3.349349 4.50545 0.785 0.25 0.318471 3.400813 3.210217 0.848 0.25 0.294811 3.030877 4.285902 0.796 0.25 0.31407 3.106001 3.067919 0.853 0.25 0.293083 2.716807 4.05777 0.807 0.25 0.309789 2.812918 2.919588 0.853 0.25 0.293083 2.407018 3.819422 0.812 0.25 0.307882 2.519835 2.763307 0.868 0.25 0.288018 2.099136 3.566796 0.829 0.25 0.301568 2.231817 2.600592 0.88 0.25 0.284091 1.797568 3.300659 0.84 0.25 0.297619 1.947726 2.429444 0.89 0.25 0.280899 1.499949 3.015062 0.853 0.25 0.293083 1.666827 2.247441 0.91 0.25 0.274725 1.206865 2.704503 0.868 0.25 0.288018 1.392102 2.053896 0.929 0.25 0.269107 0.918847 2.359824 0.9 0.25 0.277778 1.122995 3.689453 0.83 0.25 0.301205 0.641069 1.971108 0.929 0.125 0.134553 0.82179 3.15612 0.85 0.25 0.294118 0.506516 1.752082 0.527672 2.529037 0.868 0.25 0.288018 0.506516 1.752082 0.239654 <![CDATA[ 3.408752 ]]> 0.848 0.1 0.117925 0.506516 1.752082 0.12173 <![CDATA[ 2.429411 ]]> 0.875 0.05 0.057143 0.064587 <![CDATA[ 1.769597 ]]> 2.875 3.4

[0071] Table 1

[0072] Table 1 above shows the voltage values ​​relative to energy consumption for a buck-boost regulator represented by the ISL9122A, with a fixed 4mJ input for a 330μF capacitor and a switched four-element 165μF capacitor array. As shown in the table, the amount of energy extracted improves by 18%. It should be noted that while ideal conversion may not occur, reorganizing energy from a parallel configuration when fully charged to a series configuration when fully depleted can result in a desirable efficiency improvement. In this case, the remaining energy on the capacitor is negligible. Furthermore, the capacitor voltage can be kept closer to the optimal input voltage of the subsequent power supply, thereby improving average efficiency. In short, using the above-described techniques, devices, and configurations, an average efficiency of 91.6% can be maintained, resulting in a 50% reduction in conversion losses. Furthermore, using the techniques described herein, 8ms of additional air time can be obtained from, for example, low-power radio circuits.

[0073] Figure 11 An example graphical representation 1100 is depicted that includes voltage characteristics of various conventional devices relative to voltage characteristics of devices utilizing a capacitor matrix or capacitor configuration as described in the present disclosure, in accordance with one or more aspects described and illustrated herein. In particular, Figure 11A graph is shown having an x-axis representing a plurality of energy values ​​on a logarithmic scale 1102 and a y-axis representing a plurality of voltage values ​​1104. A first voltage curve 1106 represents the voltage versus energy characteristic of a typical battery having a relatively constant (2:1) voltage from 0.06 mJ to 8 mJ. A first curve 1110 shows a conventional capacitive device, such as a conventional supercapacitor, having a similar voltage range, i.e., from 1 mJ to 4 mJ. A second curve 1112 shows that the disclosed switched capacitor array with m=1 and two capacitors extends the comparable voltage range to approximately 0.25 mJ. A third curve 1114 shows that the disclosed switched capacitor array (with m=2 and four capacitors) extends the comparable voltage range down to 0.25 mJ. Assuming an initial input of energy and a constant amount of power drawn, the voltage characteristic of the supercapacitor will exhibit a monotonically decreasing voltage over time, which rapidly drops below the undervoltage limit of the load circuit. In various aspects, to counteract and overcome this drawback, various techniques can be implemented, including the use of regulators (e.g., buck-boost regulators). Buck-boost regulators operate to generate a DC output voltage that is greater than or less than the DC input voltage, and thus enable a constant output voltage to be maintained. However, such regulators have some drawbacks, including, for example, design and implementation complexity and approximately 10-20% power loss during conversion.

[0074] The capacitor matrix design as described herein addresses and overcomes these drawbacks. Specifically, the design enables stable operating voltages over an increased range of charge energy states. The stabilization of operating voltages using the capacitor matrix design of the present disclosure is illustrated by a first curve 1110 and a second curve 1112, which indicate stable voltage levels for a wider range of charge states. As the recursion order m or the number of elements m in the switch array increases, the voltage relative to energy curve of the switched capacitor array operates in a manner similar to a battery. Additionally, it is noted that the capacitor matrix design does not suffer from the drawbacks associated with batteries having short lifespans and buck-boost regulators used with a single capacitor.

[0075] In all aspects, Figure 11The voltage characteristics shown may correspond to the voltage behavior of a 500 μF capacitor that can be charged to 4 mJ of energy at a voltage of 4 V. In various aspects, such a capacitor may require 1 mJ of energy to obtain a voltage level (e.g., 1.8 V) for standard operation of various devices. In various aspects, if the 500 μF capacitor operates like multiple smaller capacitors, less total unusable energy (wasted energy) is involved in initiating and maintaining operation of the device. The first curve 1110 shows the voltage characteristics of a single (m=0) 500 μF capacitor, while the second curve 1112 and the third curve 1114 depict the voltage characteristics of an array of, for example, two (m=1) 250 μF capacitors and four (m=2) 125 μF capacitors, respectively, as part of a recursive switching array. Thus, the voltage characteristics represented by the second curve 1112 and the third curve 1114 indicate a more uniform voltage that can be maintained by a device that is different from the device having the voltage characteristics represented by the first curve 1110. While the simpler m-recursive approach can have a 2:1 voltage range, adding another non-switched capacitor in parallel can reduce the voltage range. The more general I×J structure of switches also provides a reduced granularity voltage relative to the energy curve.

[0076] Figure 12 A circuit configuration 1200 is shown in which a single-phase DC-DC power converter circuit charges a switched dynamic capacitor. Figure 12 The circuit includes coupled input and output inductors, diodes, capacitors, and a plurality of switches configured such that the switches can change the connection of the various capacitors from series to parallel based on an operating state of the switches. Figure 12 The circuit shown in FIG represents a SEPIC topology and has the advantage of having a series rectifier element at the output to prevent discharge of the bulk storage capacitor. Other DC-DC topologies may also have desirable and similar features. In various aspects, although diodes are shown, synchronous switching FETs may also improve overall efficiency.

[0077] Figure 13 A circuit configuration 1300 is shown in which each capacitor of the switchable capacitor array can be electrically connected to a specific output coil and rectifier diode. Note that in various aspects, Figure 13 In the circuit configuration, all phases switch simultaneously from a single input inductor, and all capacitors receive incremental energy approximately simultaneously.

[0078] Figure 14Circuit configuration 1400 is shown, in which the charging source for each capacitor is energized sequentially from the input, and each capacitor has a specific output coil and diode. This configuration provides the advantage of a more constant source current flow (less ripple or nearly ripple-free source current flow). In circuit configuration 1400, the diodes can be replaced with field-effect transistors (FETs). Furthermore, circuit configuration 1400 can be implemented with multiple capacitors and switches that facilitate connecting the capacitors in series and parallel connections. Note that while circuit configuration 1400 is a circuit based on m-stage recursive switches connecting 2^m (e.g., four) capacitors, different switch arrangements can be used to connect any number or array of capacitors to implement a larger or smaller number of parallel arrangements. For example, in various aspects, an array of 12 capacitors can be implemented with 6 combinations of parallel and series arrangements, while an array of 60 capacitors can be implemented with 12 combinations of parallel and series arrangements.

[0079] Figure 15 1 shows a circuit configuration 1500 based on two galvanically separated output loops, for example, at least before being interconnected by a switch matrix, according to one or more aspects described and illustrated herein. Figure 15 As shown, circuit configuration 1500 includes multiple capacitors, inductors, diodes, and FETs. The inductor is a 1:1:1 input inductor 1502 (inductive coil). In addition, the high switching current spikes of the input inductor 1502 can have efficiency losses in the impedance source. These current transients can be caused by a specific input capacitor 1504 (C in ) (e.g., relatively small capacitors). Note that slowly varying input currents can charge such capacitors. Additionally, when internal switch 1506 is grounded, these slowly varying input currents discharge through the input coil of the 1:1:1 input inductor 1502. Capacitors 1508 and 1510 provide capacitive coupling of the switching current into the inductor's output coils 1512 and 1514, which enables coupling of the input and output signals and galvanic isolation of the inductor during the power-up phase of the input inductor 1502. Note that diodes 1516 and 1518 direct current to the energy storage capacitors 1520 and 1522 regardless of the connection state of these capacitors (e.g., whether these capacitors are connected in series or in parallel). In operation, when internal switch 1506 is in the off state, the magnetic energy stored therein discharges from the output coils 1512 and 1514 and is pushed through diodes 1516 and 1518 until the coils are completely depleted of energy. In various aspects, the addition of the non-switched tank capacitor 1524 operates as a stabilizing component when transients are switched. Additionally, the addition of the non-switched tank capacitor 1524 reduces the voltage ratio by 2:1.

[0080] In various aspects, storage capacitors 1520 and 1522 are connected in a series configuration during the charging phase of diode DSER 1526. Additionally, V CELL Comparator 1528 selects the PAR 1530 or SER 1532 gate voltage to control connectivity of the storage capacitor to the load. Circuit configuration 1500 includes many advantages, such as the ability to quickly ramp up the output voltage. Other advantages include simple gate drive circuitry and switching currents, as well as a reduction in the number of FETs involved in the circuit. Note that charging of the storage capacitor is independent of the FET switches because the charging loop is galvanically isolated except for being connected by the FETs. In various aspects, a 5-winding X:1:1:1:1 coupled inductor is used, where an "X" turns ratio is utilized on the input, resulting in a 1:1:1:1 output. Furthermore, the example circuit demonstrates that it can be implemented with series, neutral, or parallel connections.

[0081] Figure 16 A circuit configuration 1600 is shown, according to one or more aspects described and illustrated herein, in which multiple inductors are operated sequentially using separate switching phases. In various aspects, it should be noted that loading the generator's inductive winding with a DC-DC converter results in a high resistance in the winding. The resulting losses are based on the average square of the current in the source winding, while energy transfer is based on the average current. It is advantageous to extract energy while maintaining the current at a specific level to improve energy extraction efficiency. Conventional DC-DC converters operate such that they charge the inductor to a peak current value or maximum "on" time at a constant voltage and then dump the stored energy into a second circuit with zero input current. This results in higher peak currents and energy losses. Input capacitance mitigates these energy losses to some extent, but leaves wasted energy at the input with each voltage dip in the rectified waveform. Sequential switching achieves a more uniform input current and facilitates modifying the on-time of each switch to maintain a balance in the associated capacitor voltages in a series connection.

[0082] In various aspects, minimizing the input capacitance is beneficial because doing so reduces wasted energy. In various aspects, a converter having N phases can be operated sequentially and can have an input duty cycle that is less than (e.g., slightly less than) 1 / N, such that the net input duty cycle can be close to 100%. Circuit configuration 1600 is a sawtooth input based circuit with non-uniform current. However, at a specific (e.g., the same) power transfer level, the current distribution of circuit configuration 1600 is more uniform than that of a low duty cycle single phase switcher. In various aspects, it should be noted that a buck-boost based circuit as described in the present disclosure can use 2 M Phase and X:(1+2 J ) winding coupled inductor to implement, which can be used to implement N = M + J recursive levels in FET switching and obtain 2N Capacitor state.

[0083] Figure 17 Circuit configuration 1700 is shown. With this configuration, input voltage 1702 can be sampled via a resistor to generate a reference current for voltage-dependent current limiting. In operation, the peak current of the input inductor can be controlled, which controls the average current associated with the winding. In various aspects, the regulating resistor is replaced by a current mirror. As a result, the current limit of the integrated circuit (IC) depends on the input voltage. In addition, for a portion of the input voltage waveform where the voltage is greater than the undervoltage lockout value, the input has an approximately constant resistance. In various aspects, the inductive winding of the electromechanical power supply 1704 generates maximum power transfer when the equivalent resistance of the DC-DC input is equal to the resistance of the winding of the electromechanical power supply. Furthermore, maximum energy is extracted when the equivalent resistance of the DC-DC input is approximately 1.5 times the resistance of the winding of the electromechanical power supply. Furthermore, circuit configuration 1700 also includes an inductive coil coupled to a rectifier (1706) for operating as a filter.

[0084] Figure 18 An example graphical representation 1800 illustrating the level of improvement in energy extraction efficiency according to one or more aspects described and illustrated herein is shown. Specifically, the example graphical representation 1800 is associated with power delivered to a regulator with a 1.8V undervoltage and a resistive load powered by a DC-DC converter and a non-switched energy storage capacitor, for example, when the DC-DC converter has a fixed resistor limit resistance of 14.7K and results in 3.08mJ of recovered energy. The example graphical representation 1800 includes an x-axis corresponding to time 1802 and a y-axis corresponding to power values ​​1804 represented in watts (W).

[0085] Figure 19 An example graphical representation 1900 is shown representing the energy extraction efficiency level associated with a circuit configuration that may not have a current mirror or capacitor switching feature. Specifically, based on replacing the fixed resistor current limit with a suitable resistor from the input voltage to the current mirror, the example graphical representation 1900 may be associated with 3.19 mJ of recovered energy.

[0086] Figure 20 An example graphical representation 2000 is shown representing energy extraction efficiency levels according to a circuit configuration that may also not have a current mirror or capacitor switching feature. Specifically, the example graphical representation 2000 is associated with 3.12 mJ of recovered energy or increased available energy for the switched capacitor relative to the single-state capacitor. This amount of recovered energy is related to Figure 21 The situation described in is quite similar.

[0087] Figure 21An example graphical representation 2100 illustrating the level of improvement in energy extraction efficiency according to one or more aspects described and illustrated herein is shown. Specifically, the example graphical representation 2100 is associated with 3.7 mJ of recovered energy when switching capacitors from a parallel configuration to a series configuration to recover some of the forgone energy.

[0088] In the following examples and claims, the term "isolated functional coupling" shall mean magnetic coupling between two or more inductors, capacitive coupling between two series-connected capacitors, or a combination of both.

[0089] In view of the above embodiments of the subject matter, the present application discloses the following list of examples, wherein one feature of an individual example or a combination of more than one feature of the example, and optionally in combination with one or more features of one or more further examples, are further examples that also fall within the disclosure of the present application:

[0090] Additional non-limiting aspect or aspects are set forth in the following numbered examples:

[0091] Example 1: A power conversion device comprising at least a first inductor and a second inductor, a rectifier, a load, and at least a first energy storage capacitor and a second energy storage capacitor, wherein: the first inductor is galvanically isolated from the second inductor, each of the first inductor and the second inductor is an output inductor of the power conversion device, the rectifier is configured to charge at least the first energy storage capacitor and the second energy storage capacitor, each of at least the first energy storage capacitor and the second energy storage capacitor is coupled to the load, and the interconnection of at least the first energy storage capacitor and the second energy storage capacitor is switched between at least one of an electrical series connection to an electrical parallel connection and an electrical parallel connection to an electrical series connection.

[0092] Example 2: A power conversion device according to Example 1, wherein the power conversion device further comprises a third inductor, wherein the third inductor is an input inductor galvanically isolated from at least the first inductor and the second inductor, and the third inductor is coupled to at least the first inductor and the second inductor via an isolation functional coupling.

[0093] Example 3: The power conversion device according to Example 1 also includes a third inductor and a fourth inductor, wherein each of the third inductor and the fourth inductor is an input inductor, at least each of the first inductor and the second inductor is electrically isolated from each of the third inductor and the fourth inductor, and at least the first inductor is electrically isolated from at least the second inductor.

[0094] Example 4: The power conversion device of Example 3, further wherein each of the first inductor and the second inductor is coupled to at least one of the third inductor and the fourth inductor via a magnetic field-based connection.

[0095] Example 5: The power conversion device of Example 3, wherein at least each of the first inductor and the second inductor is coupled to at least one of the third inductor and the fourth inductor via a capacitive connection.

[0096] Example 6: The power conversion device according to Example 3, further comprising an input source.

[0097] Example 7: The power conversion device of Example 6, wherein each of at least the first inductor and the second inductor is coupled to an input source, and the coupling to the input source is switched in an alternating manner such that only one input inductor is connected to the input source at a time.

[0098] Example 8: The power conversion device according to Example 6 also includes a plurality of switching input inductors, wherein each of the plurality of switching input inductors is coupled to a corresponding output inductor via an isolation function coupling, and each of at least the first inductor and the second inductor is coupled to a corresponding energy storage capacitor through a rectifying element.

[0099] Example 9: A system comprising at least two output inductors, a rectifier, a plurality of switches, at least two energy storage capacitors, and a load; and wherein each of the at least two output inductors is coupled to one of the at least two energy storage capacitors via the rectifier, and the plurality of switches are operable to commutate the at least two energy storage capacitors to an output in an electrically series connection or an electrically parallel connection.

[0100] Example 10: The system of Example 9, wherein the system of Example 9 is a DC-DC converter.

[0101] Example 11: A device comprising: a plurality of windings, the plurality of windings being magnetically coupled to an energy source, each of the plurality of windings having a characteristic, wherein the characteristic corresponds to inductance, current, or stored energy; a plurality of switches, each of the plurality of switches being communicatively coupled to the windings so as to place the windings in multiple combinations of series and parallel connections; and control logic that operates the plurality of switches to control the plurality of windings.

[0102] Example 12: The apparatus of Example 11, wherein the characteristic is uniform for the plurality of windings, and the plurality of windings includes two windings, and the plurality of switches includes three switches, the three switches being configurable to place the plurality of windings in a series configuration and a parallel configuration relative to a load.

[0103] Example 13: The apparatus of Example 11, wherein the plurality of windings comprises four windings and the plurality of switches comprises nine switches for configuring the plurality of windings and the plurality of switches in a 4-series, 4-parallel, and 2×2 configuration relative to a load.

[0104] Example 14: The apparatus of Example 11, wherein the plurality of windings comprises two windings, and the plurality of switches comprises seven switches for providing series and parallel connection states of the windings and positive or negative connection of the plurality of windings relative to a load.

[0105] Example 15: The apparatus of Example 11, wherein at least one switch of the plurality of switches is modulated to control power to the load.

[0106] Example 16: A system comprising: a plurality of capacitors, each of the plurality of capacitors having a characteristic, wherein the characteristic corresponds to capacitance, voltage, or stored energy; a plurality of switches, each of the plurality of switches communicatively coupled to the plurality of capacitors to place the plurality of capacitors in a plurality of combinations of series connections and parallel connections; and control logic that operates the plurality of switches to control the connection of the plurality of capacitors.

[0107] Example 17: The system of Example 16, wherein the characteristic is uniform for the plurality of capacitors; and each of the plurality of capacitors comprises two capacitors, and the plurality of switches provide series and parallel connection states of the plurality of capacitors to a source.

[0108] Example 18: The system of Example 17, wherein the plurality of capacitors includes four capacitors and the plurality of switches includes nine switches, wherein the capacitors and switches are configurable in 4-series, 4-parallel, and 2×2 configurations.

[0109] Example 19: A system comprising: a plurality of capacitors and three switches, wherein the plurality of capacitors are electrically coupled in a subcircuit based on multiple recursive stages, wherein a first stage comprises a subset of the plurality of capacitors and the three switches, and wherein the three switches are operable to change the connection of the subset of the plurality of capacitors from a series connection to a parallel connection, and from the parallel connection to the series connection.

[0110] EXAMPLE 20: The system of Example 19, further comprising a plurality of galvanically isolated output inductors, wherein each galvanically isolated output inductor of the plurality of galvanically isolated output inductors is coupled to a corresponding one of the plurality of capacitors using a rectifying component.

[0111] EXAMPLE 21 The system of Example 19, further comprising at least one input inductor, wherein the plurality of galvanically isolated output inductors are coupled to the at least one input inductor via isolation-functional coupling connections.

[0112] Example 22: A system comprising a plurality of capacitors, a rectifier, a controller, and a plurality of switches, wherein the plurality of switches are operably connected to the plurality of capacitors, and the controller is operable to control each of the plurality of switches to change the connection state of the plurality of capacitors from a series connection configuration to a parallel connection configuration and from the parallel connection configuration to the series connection configuration.

[0113] Example 23: The system of Example 22, further comprising a plurality of galvanically isolated output inductors, each of the plurality of galvanically isolated output inductors coupled to a corresponding one of the plurality of capacitors through the rectifier.

[0114] EXAMPLE 24: The system of Example 23, further comprising at least one input inductor, wherein the plurality of galvanically isolated output inductors are coupled to the at least one input inductor via isolation-functional coupling connections.

[0115] Note that the techniques described here enable low-frequency resonant energy harvesting. Furthermore, these techniques address issues associated with any energy harvesting where the voltage and current ranges far exceed the ideal ranges for harvesting electronics. The techniques and methods described above can be applied to capacitive piezoelectric harvesters and other harvesters utilizing similar combinations and methods.

[0116] The techniques and devices described herein can also be used in applications involving energy harvesting, digitally tunable inductors and capacitors. In particular, the techniques, devices, and configurations described herein are intended to provide operation such that the commutation losses of the capacitor network are small. Furthermore, these techniques can be used for applications involving adaptive filtering of EMI, constant voltage charge accumulation (solid-state batteries), adaptive charge pumps, and many other applications.

[0117] The techniques and claims herein describe digital variable capacitors and devices for powering them from power converters and chargers based on switched inductive power conversion. As a non-limiting example, these methods are equally applicable to switched capacitor power conversion, where references to output and input inductors are replaced by the input and output connection states of a charge pump's switched capacitors.

Claims

1. A power conversion device comprising: at least a first inductor and a second inductor; rectifier; load; as well as at least a first energy storage capacitor and a second energy storage capacitor; in: the first inductor being galvanically isolated from the second inductor, Each of the first inductor and the second inductor is an output inductor of the power conversion device, The rectifier is configured to charge at least the first energy storage capacitor and the second energy storage capacitor, At least each of the first energy storage capacitor and the second energy storage capacitor is coupled to the load, and The interconnection of at least the first energy storage capacitor and the second energy storage capacitor is switched between at least one of being connected in electrical series to being connected in electrical parallel and from being connected in electrical parallel to being connected in electrical series.

2. The power conversion device according to claim 1, wherein the power conversion device further comprises a third inductor, wherein: The third inductor is an input inductor galvanically isolated from at least the first inductor and the second inductor; and The third inductor is coupled to at least the first inductor and the second inductor via an isolation functional coupling.

3. The power conversion device according to claim 1 , further comprising a third inductor and a fourth inductor, wherein: Each of the third inductor and the fourth inductor is an input inductor; at least each of the first inductor and the second inductor is galvanically isolated from each of the third inductor and the fourth inductor; and At least the first inductor is galvanically isolated from at least the second inductor.

4. The power conversion device according to claim 3, further wherein: Each of the first inductor and the second inductor is coupled to at least one of the third inductor and the fourth inductor via a magnetic field based connection.

5. The power conversion device according to claim 3, wherein: At least each of the first and second inductors is coupled to at least one of the third and fourth inductors via a capacitive connection. The power conversion apparatus according to claim 3 , further comprising an input source.

7. The power conversion device according to claim 6, wherein: At least each of the first inductor and the second inductor is coupled to the input source; and The coupling to the input source is switched in an alternating manner such that only one input inductor is connected to the input source at a time.

8. The power conversion apparatus of claim 6, further comprising a plurality of switching input inductors, wherein: Each of the plurality of switched input inductors is coupled to a corresponding output inductor via an isolation functional coupling; and At least each of the first inductor and the second inductor is coupled to a corresponding energy storage capacitor through a rectifying element.

9. A system comprising: at least two output inductors; rectifier; Multiple switches; at least two energy storage capacitors; as well as load; and wherein each of the at least two output inductors is coupled to one of the at least two energy storage capacitors via the rectifier, and The plurality of switches are operable to commutate the at least two energy storage capacitors to an output in an electrical series connection or an electrical parallel connection.

10. The system of claim 9, wherein the system of claim 9 is a DC-DC converter.

11. A device comprising: a plurality of windings magnetically coupled to an energy source, each of the plurality of windings having a characteristic, wherein the characteristic corresponds to inductance, current, or stored energy; a plurality of switches, each of the plurality of switches communicatively coupled to a winding to place the windings in a plurality of combinations of series connection and parallel connection; as well as Control logic operates the plurality of switches to control the plurality of windings.

12. The apparatus of claim 11, wherein: The characteristic is uniform across the plurality of windings; and The plurality of windings includes two windings, and the plurality of switches includes three switches configurable to place the plurality of windings in a series configuration and a parallel configuration with respect to a load.

13. The apparatus of claim 11, wherein the plurality of windings comprises four windings and the plurality of switches comprises nine switches for configuring the plurality of windings and the plurality of switches in a 4-series, 4-parallel, and 2x2 configuration relative to a load.

14. The apparatus of claim 11, wherein the plurality of windings comprises two windings, and the plurality of switches comprises seven switches for providing series and parallel connection states of the windings and positive or negative connection of the plurality of windings with respect to a load.

15. The apparatus of claim 11, wherein at least one switch of the plurality of switches is modulated to control power to a load.

16. A system comprising: a plurality of capacitors, each of the plurality of capacitors having a characteristic, wherein the characteristic corresponds to capacitance, voltage, or stored energy; a plurality of switches, each of the plurality of switches communicatively coupled to the plurality of capacitors to place the plurality of capacitors in a plurality of combinations of series connection and parallel connection; as well as Control logic operates the plurality of switches to control the connection of the plurality of capacitors.

17. The system according to claim 16, The characteristic is uniform across the plurality of capacitors; and Each of the plurality of capacitors includes two capacitors, and the plurality of switches provide series and parallel connection states of the plurality of capacitors to a source.

18. The system of claim 17, wherein the plurality of capacitors comprises four capacitors and the plurality of switches comprises nine switches, wherein the capacitors and switches are configurable in 4-series, 4-parallel, and 2x2 configurations.

19. A system comprising: multiple capacitors and three switches; and The plurality of capacitors are electrically coupled in a sub-circuit based on multiple recursive stages, wherein: The first stage includes a subset of the plurality of capacitors and the three switches, and The three switches are operable to change the connection of a subset of the plurality of capacitors from a series connection to a parallel connection, and from the parallel connection to the series connection.

20. The system of claim 19, further comprising a plurality of galvanically isolated output inductors, wherein each galvanically isolated output inductor of the plurality of galvanically isolated output inductors is coupled to a corresponding one of the plurality of capacitors using a rectifying component.

21. The system of claim 19, further comprising at least one input inductor, wherein the plurality of galvanically isolated output inductors are coupled to the at least one input inductor via isolation functional coupling connections.

22. A system comprising: Multiple capacitors; rectifier; Controller; as well as Multiple switches; in: The plurality of switches are operatively connected to the plurality of capacitors, and The controller is operable to control each of the plurality of switches to change a connection state of the plurality of capacitors from a series connection configuration to a parallel connection configuration and from the parallel connection configuration to the series connection configuration.

23. The system of claim 22, further comprising a plurality of galvanically isolated output inductors, each of the plurality of galvanically isolated output inductors coupled to a corresponding one of the plurality of capacitors through the rectifier.

24. The system of claim 23, further comprising at least one input inductor, wherein: The plurality of galvanically isolated output inductors are coupled to the at least one input inductor via an isolation functional coupling connection.

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