Reconfigurable self-clamping continuous conversion ratio switched capacitor converter

Abstract

The invention belongs to the technical field of power management, and discloses a reconfigurable self-clamping continuous conversion ratio switched capacitor converter which comprises an odd number of continuous conversion ratio switched capacitor converter units, and each continuous conversion ratio switched capacitor converter unit comprises a flying capacitor CF, an output switch SOUT, input switches SINT and SINB and a grounding switch SVSS. The middle virtual level switch clamps voltage planes ST and SB, auxiliary switches SCT and SCB of a plurality of clamping voltage planes are realized, mode change is realized by changing the sequence of the switches, and an appropriate reconfigurable self-clamping mode is determined according to a voltage conversion ratio. According to the switched capacitor converter with the continuous conversion ratio, the high-efficiency voltage conversion ratio can be realized by using a small number of capacitors, and meanwhile, the voltage stress borne by the capacitors is reduced, so that the capacitors with higher density can be used. The mode is changed by changing the sequence of the switches, the mode corresponding to the input voltage is preset, and the mode with the highest efficiency can be determined by judging the magnitude of the input voltage.

Description

Technical Field

[0001] This invention belongs to the field of power management technology, specifically relating to a reconfigurable self-clamping continuous conversion ratio switched capacitor converter. Background Technology

[0002] IoT edge sensor devices, such as road monitoring sensors and environmental monitoring nodes for smart cities, portable physiological parameter monitoring devices for healthcare, and distributed vibration, temperature, and pressure sensors in industrial automation scenarios, are being deployed more and more widely in various environments. These devices are often installed in remote, dispersed, or hard-to-reach locations (such as inside bridge structures, around large equipment, in the field, or in implantable medical environments), making it difficult to conveniently and economically replace batteries at any time. To ensure long-term, stable, and autonomous operation of these devices, it is essential to rely on efficient and reliable self-powered systems to harvest and manage energy from the environment.

[0003] Currently, one common solution utilizes the photovoltaic effect to convert solar energy into electrical energy, which is then stored in small rechargeable lithium batteries or supercapacitors via power management circuits, continuously powering sensor nodes. This approach alleviates the challenge of battery replacement to some extent. However, with the continuous enhancement of IoT node functions (such as increased data transmission frequency, integration of more sensor modules, and edge computing processing), the overall energy consumption of the system has increased significantly. Traditional small-area, low-efficiency photovoltaic data collection systems often struggle to generate sufficient electrical energy under limited sunlight conditions, especially indoors, in cloudy or rainy environments, or under shady conditions. The unstable energy supply can easily lead to frequent device hibernation or interruptions, severely limiting its application scope and reliability.

[0004] Against this backdrop, photovoltaic energy harvesting systems are facing higher demands: on the one hand, they need to achieve higher energy harvesting density per unit area or volume to adapt to increasingly miniaturized sensor devices; on the other hand, they need to maximize energy conversion efficiency to maintain effective output under low-light conditions. Simultaneously, to adapt to short-term operation of high-power loads (such as the instantaneous transmission of wireless communication), the system also needs to have high instantaneous power output capability. However, existing systems often achieve higher power density and efficiency while incurring problems such as more complex circuit structures, increased components, increased static losses, and higher costs, leading to a decline in overall reliability and economic efficiency. Furthermore, the complex management circuitry itself consumes considerable energy, especially in standby or low-load states, reducing the system's net energy gain.

[0005] In photovoltaic (PV) energy harvesting systems, continuously scalable-conversion-ratio (CSCR-SCC) switched-capacitor converters play a crucial role. Specifically, the output characteristics of PV cells are highly susceptible to environmental influences. To extract every bit of energy, the system must operate at its maximum power point (MPP). The limitation of traditional SCCs: Ordinary switched-capacitor converters only have discrete voltage conversion ratios (VCRs). When changes in illumination cause a shift in the PV cell's optimal operating point voltage, the discrete ratio often fails to precisely "align" with this point, leading to a significant decrease in energy harvesting efficiency. The role of continuous conversion ratio: CSCR-SCCs, by adjusting the switching frequency, phase width, or employing a hybrid topology, make the conversion ratio quasi-continuously adjustable within a certain range. This allows the system to finely adjust the input impedance, perfectly matching the PV cell's MPP under any illumination conditions.

[0006] In micro-photovoltaic data collection (such as IoT sensors and wearable devices), the energy is extremely weak and typically does not require large inductors (which are bulky and have high EMI). Switched-capacitor circuits primarily use capacitors for energy storage, which are easily integrated on CMOS chips, significantly reducing system size. Reducing "hard charging" losses: Continuous conversion ratio technology is often combined with soft-charging or multi-phase interleaving technology to reduce energy losses during capacitor charging and discharging, maintaining high conversion efficiency over a wide voltage range (typically improving it by 5%–10%). Photovoltaic cells have extremely low output voltages under low indoor light conditions and higher voltages under strong outdoor light conditions. Continuous conversion ratio converters can automatically switch modes based on the input voltage. When the input voltage is too low, it can operate with a higher boost ratio; when the light intensity increases, it smoothly reduces the conversion ratio. This "seamless switching" capability ensures that the system can continuously charge the energy storage medium (such as lithium batteries or supercapacitors) under all-weather lighting conditions.

[0007] Therefore, designing a photovoltaic energy harvesting and management solution that achieves high energy density, high efficiency, and high power output while optimizing system architecture, control complexity, and static power consumption under limited space and light resource constraints has become a key technological challenge for promoting the large-scale, long-life, and autonomous deployment of IoT edge sensors. Existing solutions have not yet achieved an ideal balance between performance, complexity, and cost, and further research and innovation are urgently needed. Summary of the Invention

[0008] The purpose of this invention is to overcome at least one deficiency of the prior art and provide a reconfigurable self-clamping continuous conversion ratio switched capacitor converter.

[0009] The technical solution adopted in this invention is: A first aspect of the invention provides: a reconfigurable, self-clamped, continuously variable ratio (CVR) switched-capacitor converter, comprising N CVR switched-capacitor converter units, wherein N is an odd number not less than 5, and each CVR switched-capacitor converter unit includes a flying capacitor C. F Output switch S OUT Connect to input switch S INT and S INB Grounding switch S VSS Intermediate virtual level switch clamping voltage plane S T and S B The continuous conversion ratio switched capacitor converter units are further provided with auxiliary switches S to realize multiple clamping voltage planes. CT and S CB Flying capacitor C F Top plate connection S OUT S INT S T S CT Base plate connection switch S INB S VSS S B S CB Each switch is controlled by an independent control signal; The auxiliary switch is controlled by a clamping mode selection module. The mode is changed by changing the order of the switches, and a suitable reconfigurable self-clamping mode is determined according to the voltage conversion ratio.

[0010] In some instances, the continuous conversion ratio is higher than the flying capacitance C of the switched capacitor converter unit. F A virtual node V is provided in the top plate. T A virtual intermediate node V is provided on the base plate. B Each continuous conversion ratio switched capacitor converter unit operates in one of the following four phases: Phase B: Top plate fixed, bottom plate connected to virtual node V B ; T-phase: Top plate connects to virtual node V T The base plate is fixed; C-phase: clamping; and Phase D: Foundation.

[0011] In some instances, each flying capacitor enters its operating phase with a two-phase delay relative to the previous capacitor, forming an inter-clamping-stage out-of-phase configuration, which splits each virtual node into two virtual levels.

[0012] In some instances, when the input voltage V IN Less than the output voltage V OUT At 1 / 3, by stacking two flying capacitors in series, the capacitor voltage stress is reduced, and two clamping plane voltages V are generated. clampT2 = 2V OUT / 3 and V clampT1 = V OUT / 3.

[0013] In some instances, when the output voltage V OUT 1 / 3 ≤ Input voltage V IN Less than or equal to the output voltage V OUT At 1 / 2, under clamping phase, the top plates of each flying capacitor are sequentially connected to V. OUT Its base plate serves as the output of other continuous conversion ratio switched capacitor converter units, generating a clamping plane voltage V. clampT equals V OUT / 2.

[0014] In some instances, when the input voltage V IN Greater than the output voltage V OUT At 1 / 2, under clamping phase, the base plates of each flying capacitor are sequentially connected to V. SS Its top plate serves as the reference ground node for other continuous-ratio switched-capacitor converter units, generating a clamping plane voltage V. clampT equals V OUT / 2.

[0015] In some instances, 7 ≤ N ≤ 21.

[0016] In some instances, the number of clamping voltage planes is no less than two.

[0017] In some instances, the number of clamping voltage planes is three.

[0018] In some instances, the intermediate virtual level switch clamping voltage plane S T and S B The number of groups is 2 to 5.

[0019] In some instances, the intermediate virtual level switch clamping voltage plane S T and S B There are 3 groups.

[0020] The above features can be combined arbitrarily as long as they do not conflict with each other.

[0021] A second aspect of the present invention provides: a photovoltaic energy harvesting device having the continuous conversion ratio switched capacitor converter described in the first aspect of the present invention.

[0022] The beneficial effects of this invention are: The continuous conversion ratio switched capacitor converters of some embodiments of the present invention can achieve high-efficiency voltage conversion ratios using a small number of capacitors, while reducing the voltage stress on the capacitors, thereby enabling the use of higher-density capacitors.

[0023] In some embodiments of this invention, the continuous conversion ratio switched capacitor converter achieves mode change by altering the switching sequence. By pre-setting the mode corresponding to the input voltage, the appropriate mode can be determined by judging the input voltage magnitude. The suitability of the mode is determined by the calculated efficiency; the mode with the highest efficiency in this case is used.

[0024] The continuous conversion ratio switched capacitor converter of some embodiments of the present invention achieves a high efficiency voltage conversion ratio of up to 3.83 using only 13 capacitors, while reducing the voltage stress on the capacitors, thereby enabling the use of higher density capacitors and achieving 17.1 mW / mm². 2 It has a high power density and a peak power conversion efficiency of 90%. Attached Figure Description

[0025] Figure 1 This is a circuit diagram of a reconfigurable self-clamped continuous conversion ratio (CSCR) switched capacitor converter.

[0026] Figure 2 This is a schematic diagram of the operation of a self-clamping continuous conversion ratio switched capacitor converter (×2T clamping mode).

[0027] Figure 3 This is a schematic diagram of the ×2B clamp mode operation.

[0028] Figure 4 This is a schematic diagram of the ×3T clamping mode.

[0029] Figure 5 This is a schematic diagram of the operation of clamp-stage out-of-phase (CSO).

[0030] Figure 6 It is the result of the power conversion efficiency (PCE) variation of each clamping mode individually within a limited voltage ratio (VCR) range.

[0031] Figure 7 This is a schematic diagram illustrating the working principle of a reconfigurable self-clamping continuous ratio switched capacitor converter in ×2T clamping mode.

[0032] Figure 8This is a circuit waveform diagram in ×2T clamp mode without using inter-clamp stage out-of-phase (CSO) technology.

[0033] Figure 9 This is a circuit waveform diagram using the ×2T clamping mode with CSO technology. Detailed Implementation

[0034] A reconfigurable, self-clamped, continuously variable ratio (CVR) switched-capacitor converter includes N CVR switched-capacitor converter units, where N is an odd number not less than 5. Each CVR switched-capacitor converter unit includes a flying capacitor C. F Output switch S OUT Connect to input switch S INT and S INB Grounding switch S VSS Intermediate virtual level switch clamping voltage plane S T and S B The continuous conversion ratio switched capacitor converter units are further provided with auxiliary switches S to realize multiple clamping voltage planes. CT and S CB Flying capacitor C F Top plate connection S OUT S INT S T S CT Base plate connection switch S INB S VSS S B S CB Each switch is controlled by an independent control signal; The auxiliary switch is controlled by a clamping mode selection module. The mode is changed by changing the order of the switches, and a suitable reconfigurable self-clamping mode is determined according to the voltage conversion ratio.

[0035] Auxiliary switch S CT and S CB The number of groups can be arbitrary, with one group of switches corresponding to one clamping plane.

[0036] In some instances, the continuous conversion ratio is higher than the flying capacitance C of the switched capacitor converter unit. F A virtual node V is provided in the top plate. T A virtual intermediate node V is provided on the base plate. B Each continuous conversion ratio switched capacitor converter unit operates in one of the following four phases: Phase B: Top plate fixed, bottom plate connected to virtual node V B ; T-phase: Top plate connects to virtual node V T The base plate is fixed; C-phase: clamping; and Phase D: Foundation.

[0037] In some instances, each flying capacitor enters its operating phase with a two-phase delay relative to the previous capacitor, forming an inter-clamping-stage out-of-phase configuration, which splits each virtual node into two virtual levels.

[0038] In some instances, when the input voltage V IN Less than the output voltage V OUT At 1 / 3, by stacking two flying capacitors in series, the capacitor voltage stress is reduced, and two clamping plane voltages V are generated. clampT2 = 2V OUT / 3 and V clampT1 = V OUT / 3.

[0039] In some instances, when the output voltage V OUT 1 / 3 ≤ Input voltage V IN Less than or equal to the output voltage V OUT At 1 / 2, under clamping phase, the top plates of each flying capacitor are sequentially connected to V. OUT Its base plate serves as the output of other continuous conversion ratio switched capacitor converter units, generating a clamping plane voltage V. clampT equals V OUT / 2.

[0040] In some instances, when the input voltage V IN Greater than the output voltage V OUT At 1 / 2, under clamping phase, the base plates of each flying capacitor are sequentially connected to V. SS Its top plate serves as the reference ground node for other continuous-ratio switched-capacitor converter units, generating a clamping plane voltage V. clampT equals V OUT / 2.

[0041] The more continuous switching capacitor converter units there are, the higher the efficiency, but the corresponding chip area is also larger. Considering both cost and conversion efficiency, in some instances, 7≤N≤21, preferably 11 to 15 units, and in particular, 13 units.

[0042] The more clamping voltage planes there are, the finer the clamping voltage plane division can be achieved, which is beneficial for more precise control. However, a greater number of clamping voltage planes also means a larger chip area and higher cost. In some examples, the number of clamping voltage planes is no less than two.

[0043] In some instances, the number of clamping voltage planes is three.

[0044] In some instances, the intermediate virtual level switch clamping voltage plane S T and S B The number of groups is 2 to 5.

[0045] In some instances, the intermediate virtual level switch clamping voltage plane S T and S B There are 3 groups.

[0046] The technical solution of the present invention will be further illustrated below with examples.

[0047] Figure 1 shows a circuit diagram of a reconfigurable self-clamping continuous conversion ratio (CSCR) switched-capacitor converter composed of N (N≥7) subunits. In addition to the switches required for operation of a conventional continuous conversion ratio switched-capacitor converter (connected to output switch S),... OUT Connect to input switch S INT and S INB Grounding switch S VSS Intermediate virtual level switch S T1-3 and S B1-3 In addition to the above, an auxiliary switch (clamping voltage plane S) was also used. CT1-3 and S CB1-3 This allows for the implementation of three clamping voltage planes. The circuit also includes a clamping mode selection module to determine the appropriate reconfigurable self-clamping mode based on the voltage conversion ratio.

[0048] Figure 2 shows a schematic diagram of the proposed self-clamping continuous conversion ratio switched capacitor converter in operation. The flying capacitors, connected in a specific order to the upper and lower plates of other flying capacitors, undergo continuous charging and discharging processes to transfer charge from the input to the output. The capacitor charging process is the same as in traditional continuous conversion ratio switched capacitor converters, using several small phases to achieve step-by-step charging of the capacitor from a small voltage to V. calmpT Next comes the clamping phase, where the top plate of the capacitor is connected to V. OUT The base plate serves as the output for other sub-units, and then returns to the phase operation of a traditional continuous-current switching capacitor converter for small-voltage step discharge. Whenever one capacitor completes its clamping action, another capacitor immediately takes over and performs the clamping action. All capacitors operate identically, differing only in sequence. Each flying capacitor simultaneously acts as a clamping capacitor at a specific stage, for example, C... F1 and C F2 The remaining sub-units are clamped during phases 2 and 3, respectively, before resuming normal operation of the continuous conversion ratio switched capacitor converter. These operations form a virtual clamping voltage plane V throughout the duty cycle. clamp .

[0049] The topology proposed in this invention supports the reconstruction of multiple clamping configurations to adapt to performance optimization requirements under different input conditions. Specifically, when the voltage V OUT 1 / 3 ≤ Input voltage V IN ≤Voltage V OUT At 1 / 2, under clamping phase, the top plates of each flying capacitor are sequentially connected to V. OUT Their base plates serve as the outputs for other sub-units. This configuration is called the ×2T clamp mode (Figure 2), which generates a clamping plane voltage V. clampT equals V OUT / 2.

[0050] When the input voltage V IN Greater than the output voltage V OUT At half the time, under the clamping phase, the base plates of each flying capacitor are sequentially connected to V. SS Their top plates serve as reference ground nodes for other sub-units. This configuration is called the ×2B clamping mode. Figure 3 The resulting clamping plane voltage V clampB equals V OUT / 2.

[0051] When the input voltage V IN Less than the output voltage V OUT At one-third of the capacity, the ×3T clamping mode (Figure 4) further reduces capacitor voltage stress and generates two clamping plane voltages V by stacking two flying capacitors in series. clampT2 = 2V OUT / 3 and V clampT1 = V OUT / 3.

[0052] Furthermore, this invention divides the virtual node into finer steps (Figure 5) by interleaving the phases of clamping capacitors (i.e., capacitors in clamped phase operating state) and non-clamping capacitors (capacitors in normal CSCR operating state), a process known as Clamp stage out-phasing (CSO). Specifically, the ×2B clamping mode separates the VT node (the virtual intermediate level obtained by connecting the upper plates of the capacitors in CSCR operating state), while the ×2T and ×3T clamping modes separate the V node. B The node (i.e., the virtual intermediate level obtained by connecting the lower plate of the capacitor to the lower plate in the CSCR working state).

[0053] As shown in Figure 6, each clamping mode achieves high power conversion efficiency (PCE) within a limited voltage ratio (VCR) range. Reconfigurability extends the high PCE range beyond the conventional CSCR, while CSO improves PCE across the entire VCR range.

[0054] Figure 7 shows a schematic diagram of the proposed 13-subunit reconfigurable self-clamping continuous-ratio switched-capacitor converter in ×2T clamping mode. This structure has two intermediate nodes (V...) on the top plate. T1-2 The base plate has three intermediate nodes (V). B1-3 Each sub-unit operates in one of the following four phases: Phase B (top plate fixed, bottom plate connected to virtual node V). B1-3 ), T phase (top plate connection V) T1-2 The system consists of a base plate (fixed), a C phase (clamping), and a D phase (foundation). Each flying capacitor enters its operating phase with a two-phase delay relative to the previous capacitor. This out-of-phase configuration splits each virtual node into two virtual levels, resulting in 26 effective operating phases.

[0055] Figure 8 shows the circuit waveforms in ×2T clamp mode without the use of clamp-stage out-of-phase (CSO) technology. The critical node voltage is the clamp plane voltage V. clampT V, the voltage at the top node of the flying capacitor Ts Bottom node voltage V Bs Due to the presence of out-of-phase voltage, each voltage node is split into two virtual levels. The simulation diagram shows the capacitor bottom voltage V with three bottom nodes. B There will be 6 virtual levels, as theoretically analyzed.

[0056] Figure 9 shows the circuit waveforms in the ×2T clamping mode using CSO technology. The C phase (clamping) and D phase (foundation) are rearranged in a phase-interleaved manner to achieve the effect of phase interleaving between clamping and non-clamping capacitors, dividing the virtual node into finer steps. Due to the presence of CSO technology, V Bs The original two virtual voltage levels were split into four virtual voltage levels. The simulation diagram shows that, using CSO technology, the voltage V at the bottom of the capacitor... B There will be 12 smaller virtual levels, as in the theoretical analysis.

[0057] Some embodiments of the present invention provide a continuous conversion ratio switched capacitor converter integrated into a single chip with an effective area of ​​3.52 mm². 2 On the chip, tests showed that with an input of 2V and an output of 3.8V, the maximum output power was 60.2mW, and the power density was 17.1mW / mm². 2 The peak conversion efficiency is 90% when the input is 2V and the output is 2.4V (conversion efficiency = output power / total input power).

[0058] The above is a further detailed description of the present invention and should not be considered as a limitation on the specific implementation of the present invention. For those skilled in the art, simple deductions or substitutions without departing from the concept of the present invention are all within the protection scope of the present invention.

Claims

1. A reconfigurable, self-clamping, continuously variable ratio switched-capacitor converter, characterized in that, It includes N continuously variable switching capacitor converter units, where N is an odd number not less than 5, and each continuously variable switching capacitor converter unit includes a flying capacitor C. F Output switch S OUT Connect to input switch S INT and S INB Grounding switch S VSS Intermediate virtual level switch clamping voltage plane S T and S B The continuous conversion ratio switched capacitor converter units are further provided with auxiliary switches S to realize multiple clamping voltage planes. CT and S CB Flying capacitor C F Top plate connection S OUT S INT S T S CT Base plate connection switch S INB S VSS S B S CB Each switch is controlled by an independent control signal; The auxiliary switch is controlled by a clamping mode selection module. The mode is changed by changing the order of the switches, and a suitable reconfigurable self-clamping mode is determined according to the voltage conversion ratio.

2. The continuous conversion ratio switched capacitor converter according to claim 1, characterized in that, The flying capacitor C of the continuous conversion ratio switched capacitor converter unit F A virtual node V is provided in the top plate. T A virtual intermediate node V is provided on the base plate. B Each continuous conversion ratio switched capacitor converter unit operates in one of the following four phases: Phase B: Top plate fixed, bottom plate connected to virtual node V B ; T-phase: Top plate connects to virtual node V T The base plate is fixed; C-phase: clamping; and Phase D: Foundation.

3. The continuous conversion ratio switched capacitor converter according to claim 2, characterized in that, Each flying capacitor enters its operating phase with a two-phase delay relative to the previous capacitor, forming an inter-clamping stage out-of-phase configuration. This inter-clamping stage out-of-phase configuration splits each virtual node into two virtual levels.

4. The continuous conversion ratio switched capacitor converter according to claim 1, characterized in that, When the input voltage V IN Less than the output voltage V OUT At 1 / 3, by stacking two flying capacitors in series, the capacitor voltage stress is reduced, and two clamping plane voltages V are generated. clampT2 = 2V OUT / 3 and V clampT1 = V OUT / 3.

5. The continuous conversion ratio switched capacitor converter according to claim 1, characterized in that, When the output voltage V OUT 1 / 3 ≤ Input voltage V IN Less than or equal to the output voltage V OUT At 1 / 2, under clamping phase, the top plates of each flying capacitor are sequentially connected to V. OUT Its base plate serves as the output of other continuous conversion ratio switched capacitor converter units, generating a clamping plane voltage V. clampT equals V OUT / 2.

6. The continuous conversion ratio switched capacitor converter according to claim 1, characterized in that, When the input voltage V IN Greater than the output voltage V OUT At 1 / 2, under clamping phase, the base plates of each flying capacitor are sequentially connected to V. SS Its top plate serves as the reference ground node for other continuous-ratio switched-capacitor converter units, generating a clamping plane voltage V. clampT equals V OUT / 2.

7. The continuous conversion ratio switched capacitor converter according to claim 1, characterized in that, 7≤N≤21。 8. The continuous conversion ratio switched capacitor converter according to claim 1, characterized in that, The number of clamping voltage planes is not less than two; and / or the intermediate virtual level switch clamping voltage plane S T and S B The number of groups is 2 to 5.

9. The continuous conversion ratio switched capacitor converter according to claim 8, characterized in that, The number of clamping voltage planes is 3; and / or the intermediate virtual level switch clamping voltage plane S T and S B There are 3 groups.

10. A photovoltaic energy harvesting device, characterized in that, A continuously switching ratio switched capacitor converter as described in any one of claims 1 to 9.

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