Decentralized Successive Approximation Power Management Method for STC Converter Arrays

Abstract

The present invention discloses a decentralized successive approximation power management method applicable to an STC converter array, belonging to the technical field of power generation, power transformation or power control management. Aiming at the defect that a single switched-capacitor converter can only achieve a fixed-ratio voltage transformation function during normal operation and cannot achieve flexible voltage regulation like a switched-inductor converter, by modularizing and arraying the STC converters, according to different levels of power output requirements or voltage requirements, the number of working phases and stages of the modular converters is adjusted horizontally or vertically, and the working state of the STC converter array is adjusted successively by approximation until the output voltage is within the target range. For the STC converter array, the decentralized successive approximation power management strategy proposed by the present invention can increase the working states of the unit converters and enhance the voltage regulation ability of the modular STC converter array without reducing the efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of power generation, power transformation or power control management, and particularly relates to a decentralized successive approximation power management method applicable to an STC converter array. Background Art

[0002] In modern power electronics technology, the power supply miniaturization technology has gradually become a very important technology with strategic and forward-looking significance. Power supply miniaturization refers to reducing the volume of existing traditional power supplies from the brick-like size to the size of a conventional chip through highly integrated and packaging technologies. The output of a micro-power module at the chip scale can reach the kilowatt level, enabling ultra-high power density output. Micro-power supplies will play an indispensable role in the future in fields such as aviation, aerospace drones, and robots that are sensitive to the volume and weight of power supplies.

[0003] Google Labs proposed the high-frequency switched capacitor STC converter (Switched Tank Converter) and its cascaded topology. By connecting multiple STC converter modules in series at the input and in parallel at the output, large current output and high voltage input can be achieved simultaneously. The input-series output-parallel topology of this high-frequency switched capacitor converter provides a certain possibility for realizing miniaturized power supplies.

[0004] In terms of the control of power supply architectures composed of multiple power modules, related research mainly focuses on the control technology of multi-phase interleaved parallel buck converters. However, traditional multi-phase parallel technologies can only achieve low-voltage large-current output and cannot handle high input voltage stress, while the input-series output-parallel STC array can handle such problems. At the same time, multi-phase interleaved parallel buck converters usually use the phase shedding technology to improve the light-load efficiency of the system. Different from the multi-phase parallel structure, the input-series output-parallel structure naturally has a power distribution function and will not have a power mismatch phenomenon. Therefore, for the input-series output-parallel STC array, only common duty cycle control is required, reducing the control complexity.

[0005] The above-mentioned current sharing control technology and phase shedding technology of multi-phase interleaved parallel buck converters, as well as the related STC converter cascaded control technology proposed by Google Labs, all have the defect of requiring unified control by a central controller, which limits the scalability when combining a large number of power modules, that is, the integrable degree of micro-power supplies. Therefore, under the premise of decentralized control in the input-series output-parallel architecture of STC modules, it is necessary to study the functions of independent voltage regulation and power distribution of STC modules.

[0006] Since the switched-capacitor converter has the defect that it can only achieve a fixed-ratio voltage conversion function during normal operation and cannot achieve flexible voltage regulation like the switched-inductor converter. To enhance the voltage regulation ability of the STC modular array system architecture, it is necessary to study the voltage regulation and power distribution control strategies for individual modules to make the output voltage approach the desired output range and optimize the efficiency. Ultimately, under the condition of optimal efficiency, the operating states of the unit STC converters need to be increased to achieve the voltage regulation function of the STC array. Summary of the Invention

[0007] The object of the present invention is to provide a decentralized successive approximation power management method applicable to an STC converter array in view of the deficiencies of the above-mentioned existing technologies. By decentralizing the adjustment of the number of normal working stages and phases in the array composed of M×N groups of STC modules, the output voltage of the entire system gradually approaches the desired value, and at the same time, the output efficiency of the entire system gradually approaches the optimal efficiency. The functions of independent voltage regulation and power distribution of a single STC module are realized, and the technical problem that the existing STC module array lacks a decentralized control scheme and cannot be extended to achieve high-power density power output is solved.

[0008] The technical solution for achieving the object of the present invention is: a decentralized successive approximation power management method applicable to an STC converter array, the method includes:

[0009] By controlling the number of normal working stages of the power switched-capacitor resonant tank converter in the STC converter array, that is, the STC module, the output voltage is adjusted to achieve successive approximation voltage regulation;

[0010] By controlling the number of normal working phases of the system architecture, similar to the output voltage adjustment method, the output efficiency is adjusted to achieve successive approximation phase regulation;

[0011] The overall system architecture does not include a central controller. Each STC module directly samples its own output voltage and inductor current, and combines the states of the surrounding STC modules, and adjusts its own working state through a control circuit to achieve the adjustment of the number of stages and phases of the entire system.

[0012] Further, the STC converter array is formed by connecting M×N groups of STC modules in series at the input and in parallel at the output. The state of each STC module is divided into three types: normal working state, ON state, and OFF state;

[0013] When the STC module is in the ON state, the two switching tubes S1 and S2 of the half-bridge at the input end of the power module are always on as wires, and the two switching tubes S3 and S4 of the half-bridge at the output end are always off; when the STC module is in the OFF state, all the switching tubes of the power module are turned off, and the entire power module does not participate in the work.

[0014] Further, the number of stages for controlling the normal operation of the STC module is adjusted to regulate the output voltage, achieving successive approximation voltage regulation. The specific process is as follows:

[0015] During soft start, all power STC modules operate normally. Subsequently, based on the result of output voltage sampling, the operating state of the modules is adjusted in a successive approximation manner. Specifically: The output voltage is compared with the set upper and lower window thresholds. When the output voltage is within the hysteresis window, the operating state of the module remains unchanged; when the output voltage is lower than the lower window threshold, if the upper-level module is in the ON state, the operating state of this module is switched to the ON state, otherwise the operating state remains unchanged; when the output voltage is higher than the upper window threshold, check whether the lower-level module is in the ON state. If so, keep the operating state of this module as the ON state, otherwise switch the operating state of this module to the non-ON state; By adjusting the number of series operating stages through the above control logic, the output voltage is adjusted to the target range.

[0016] Further, the number of phases for the normal operation of the control system architecture is adjusted to regulate the output efficiency, achieving successive approximation phase modulation. The specific process is as follows:

[0017] During load switching, the STC module in the OFF state waits for the enable signal from the previous-phase module. When the enable signal is received, the current module switches to the normal operating state; Each STC module in the normal operating state can sample the peak current of this module and compare it with the set upper and lower limit thresholds. When the peak current is within the hysteresis window, the operating state of the module remains unchanged; when the peak current is lower than the lower limit threshold, the operating state of the module is switched to the OFF state; when the peak current is higher than the upper limit threshold, check whether the next-phase module is in the OFF state. If so, the operating state of the current-phase module remains unchanged, otherwise a normal operating signal is sent to the next-phase module. By combining the operating states of the previous and next-phase modules, in a scheme similar to successive approximation voltage regulation, the number of phases of the participating operating modules is adaptively adjusted in a successive approximation manner to optimize the total efficiency and make the efficiency optimal.

[0018] Further, each STC module independently uses a high-speed current sampling circuit to directly sample the inductor current and simultaneously sample the output voltage. By combining the states of the four STC modules adjacent above, below, left, and right, the logical operating state of a single STC module is obtained through the control circuit, and the conduction and cutoff of the power transistor of this module are controlled by the logical operating state to adjust the operating state of this module.

[0019] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the following steps are implemented:

[0020] By controlling the number of stages for the normal operation of the power switch-capacitor resonant tank converters, i.e., STC modules, in the STC converter array, the output voltage is regulated to achieve successive approximation voltage regulation;

[0021] Adjust the output efficiency by controlling the number of phases in which the control system architecture operates normally, and achieve phase modulation by successive approximation;

[0022] The overall system architecture does not include a central controller. Each STC module directly samples its own output voltage and inductor current, and combines the states of the surrounding STC modules to adjust its own operating state through a control circuit, thereby achieving the adjustment of the number of stages and the number of phases of the entire system.

[0023] A computer-readable storage medium stores a computer program thereon. When the computer program is executed by a processor, the following steps are implemented:

[0024] Adjust the output voltage by controlling the number of stages in which the power switch-capacitor resonant tank converter, i.e., the STC module, in the STC converter array operates normally, and achieve voltage regulation by successive approximation;

[0025] Adjust the output efficiency by controlling the number of phases in which the control system architecture operates normally, and achieve phase modulation by successive approximation;

[0026] The overall system architecture does not include a central controller. Each STC module directly samples its own output voltage and inductor current, and combines the states of the surrounding STC modules to adjust its own operating state through a control circuit, thereby achieving the adjustment of the number of stages and the number of phases of the entire system.

[0027] Compared with the prior art, the remarkable advantages of the present invention are:

[0028] (1) The strategy of the present invention uses a decentralized control scheme to control the STC array, solving the defect that the switched-capacitor converter can only achieve a fixed-ratio voltage conversion function during normal operation and cannot achieve flexible voltage regulation like the switched-inductor converter. By self-adaptive adjustment of each module to control the effective number of stages, the voltage regulation ability of the STC array is enhanced.

[0029] (2) The strategy of the present invention uses a decentralized control scheme to control the STC array, optimizing the problem of system efficiency reduction during load switching. Through self-adaptive adjustment of each module, combined with the states of the surrounding modules, and through simple control circuits such as comparators and logic gates, the effective number of phases of the STC module is controlled, enhancing the efficiency optimization of the STC array.

[0030] (3) The strategy of the present invention uses a decentralized control scheme to control the STC array, breaking the limitation of traditional centralized control. By using simple inter-module communication, the control of its own state can be achieved, which is efficient and simple, enhancing the scalability of the STC module, and providing a control strategy for realizing a high-power-density miniaturized power supply.

[0031] The present invention will be further described in detail below with reference to the accompanying drawings. Brief Description of the Drawings

[0032] Figure 1 is the structural block diagram of the STC array control strategy of the present invention.

[0033] Figure 2 is the circuit diagram of the STC array for realizing decentralized successive approximation control of the present invention.

[0034] Figure 3 is the schematic diagram of three working states of the STC module of the present invention, where (a) - (c) are the normal working state, ON state, and OFF state respectively.

[0035] Figure 4 is the block diagram of the stage-by-stage successive approximation voltage regulation logic of the STC module of the present invention.

[0036] Figure 5 is the block diagram of the phase-by-phase successive approximation efficiency optimization logic of the STC module of the present invention.

[0037] Figure 6 is the schematic diagram of the system-level voltage regulation of the present invention.

[0038] Figure 7 is the schematic diagram of the system-level current regulation of the present invention.

[0039] Figure 8 is the graph of the voltage and working current variation during the voltage regulation process of the simulated four-phase three-stage STC array of the present invention.

[0040] Figure 9 is the graph of the voltage and working current variation during the load variation process of the simulated four-phase three-stage STC array of the present invention. Detailed Embodiment

[0041] In order to make the objectives, technical solutions and advantages of this application clearer, the following further details this application in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0042] As Figure 1 shown, the decentralized successive approximation power management strategy proposed by the present invention is applicable to an STC array composed of M×N groups of STC modules. The STC array can be divided into three regions, namely the normal working region, the off-state working region, and the on-state working region. In the normal working region, all STC modules are adaptively adjusted. In the off-state working region, all STC modules are in the OFF state. In the on-state working region, all STC modules are in the ON state.

[0043] As Figure 2 shown, in the M×N-stage STC array applicable to the present invention, all STC modules are connected in series at the input and in parallel at the output. InFigure 2 In the shown circuit connection, each power STC module individually uses a high-speed current sampling circuit to directly sample its own inductor current and simultaneously sample the output voltage. By combining the states of surrounding modules, the control circuit such as comparators and logic gates obtains the logical working state of a single module, and determines the working state of the module by controlling the conduction and cutoff of the power transistors of the module.

[0044] As Figure 3 shown, after the STC module obtains its own state control logic through comparators and gate circuits, and by combining the states of surrounding modules, it can obtain three working states. First is the normal working state. In this working state, the STC module realizes the voltage transformation function. The voltage transformation ratio of a single STC module is 1:1, and a cascaded STC array can realize the voltage regulation function. When the STC module is in the ON state, the two switching transistors S1 and S2 of the half-bridge at the input end of the power module are always on, short-circuiting the STC as a wire, and the two switching transistors S3 and S4 of the half-bridge at the output end are always off. When the STC module is in the OFF state, all the switching transistors of the power module are turned off, and the entire power module does not participate in the work. By controlling the respective numbers of STC modules in these three working states in the M×N group of STC arrays, the regulation of the output voltage and the regulation of the working efficiency are achieved.

[0045] As Figure 4 shown, the decentralized STC array stage-by-stage approximation voltage regulation control strategy logic is that during soft start, all power STC modules work normally. Subsequently, according to the result of the output voltage sampling, the working states of the modules are adjusted in a stage-by-stage approximation manner. The modules in the OFF state remain unchanged. For the modules in the normal working state, after the system starts working, the sampled output voltage is compared with the upper and lower window thresholds. When the output voltage is between the hysteresis windows, the working state of the module remains unchanged. When the output voltage is lower than the lower threshold, if the upper-level module is in the ON state, the working state of this module is switched to the ON state, otherwise the working state remains unchanged. When the output voltage is higher than the upper threshold, check whether the lower-level module is in the ON state. If it is in the ON state, keep this module also in the ON state, otherwise the working state of the module is switched to a non-ON state. By adjusting the series working stages through such control logic, the output voltage is adjusted to the target range.

[0046] As Figure 5As shown in the figure, the decentralized STC array stage-by-stage approximation regulation efficiency control strategy logic means that when the load switches, the modules in the OFF state wait for the enable signal of the previous-phase module. When the enable signal is received, the current module switches to the normal working state. The modules in the ON state remain unchanged. The power STC module in the normal working state can sample the peak current of the module and compare it with the upper and lower threshold values. When the peak current is within the hysteresis window, the working state of the module remains unchanged. When the peak current is lower than the lower threshold value, the working state of the module switches to the OFF state. When the peak current is higher than the upper threshold value, it is read whether the next-phase module is in the OFF state. If so, the working state of the current module remains unchanged. Otherwise, a normal working signal is sent to the next-phase module. By combining the working states of the previous-phase and next-phase power modules, in a scheme similar to the successive approximation voltage regulation, the number of phases of the participating working modules is adaptively adjusted step by step to optimize the total efficiency and make the efficiency optimal.

[0047] As Figure 6 shown in the figure, it is the change process of the output voltage when the input voltage gradually increases. When the input voltage gradually increases, the logic control signal obtained by sampling the output voltage is processed, and the number of normal working stages N increases, reflecting that the output voltage shows a state of successive approximation regulation when the input voltage gradually increases. In theory, when N can be very large and vin can also be very large, precise voltage regulation can be achieved. When N and the input VIN are limited, the effective number of working stages N is adaptively adjusted to make the output voltage of the entire system enter the target threshold range.

[0048] As Figure 7 shown in the figure, it is the change process of the module working current during the change of the load current. When the load current gradually increases, the logic control signal obtained by sampling the output voltage is processed, and the number of normal working phases M increases, reflecting that when the load current gradually increases, the number of normal working phases M gradually increases, presenting a state of successive approximation regulation of the optimal working efficiency, that is, the strategy of the present invention achieves the effect of good decentralized successive approximation regulation efficiency applicable to the STC array.

[0049] As a specific example, as Figure 8 shown in the figure, a 4-phase 3-stage STC array system-level architecture is built in the SIMPLIS simulation software to simulate and verify the present invention. It is set that the input voltage undergoes a step mutation, changing from 48V to 24V. The upper and lower threshold values of the voltage comparison are set to 11V and 14V respectively, and it is expected that the output voltage can be stabilized near 12V, and the expected number of enabled module stages switches from 3 stages to 1 stage. It can be seen that the input voltage mutates at 1ms, and after a short adjustment, the output voltage still stabilizes near 12V. The second-stage module and the third-stage module are in the ON state, and the inductor current of the corresponding module drops to zero. That is, the simulation proves that the strategy of the present invention achieves the effect of good decentralized successive approximation regulation voltage applicable to the STC array.

[0050] As a specific example, as Figure 9 shown, a 4-phase 3-level STC array system-level architecture was built in the SIMPLIS simulation software for simulation verification. The output load was set to experience a step change, from 6 A to 30 A. The upper and lower thresholds for current comparison were set to 9 A and 18 A respectively, and it was expected that the inductor current could be stabilized within the threshold range. It can be seen that when the system was just started, all the power modules of each phase were in the on state. At this time, the load was 6 A, and the current flowing through each phase was 1.2 A, which was much less than the lower threshold of 9 A. When the fourth phase, the third phase, and the second phase modules were turned off in sequence, and only the last first-phase STC module array remained, the sampled inductor current was 5 A but was not turned off anymore. When the load changed from 6 A to 30 A, the working current in the first-phase module increased rapidly to 25 A, exceeding the upper threshold. Then the second-phase module was turned on to share the working current, and it could be obtained that the working current of both phases was about 12 A. That is, the simulation proved that the strategy of the present invention achieved the effect of good decentralized successive approximation regulation efficiency applicable to the STC array.

[0051] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. There can be many variations in the present invention described herein, and such variations should not deviate from the spirit and scope of the present invention artificially. Therefore, all changes that are obvious to those skilled in the art should be included within the scope covered by the present invention.

Claims

1. A decentralized successive approximation power management method applicable to an STC converter array, characterized in that, The method includes: By controlling the number of normally operating stages of the power switch-capacitor resonant tank converters, i.e., the STC modules, in the STC converter array, the output voltage is regulated to achieve successive approximation voltage regulation; By controlling the number of phases of the normal operation of the control system architecture, the output efficiency is regulated to achieve successive approximation phase regulation; The overall system architecture does not include a central controller. Each STC module directly samples its own output voltage and inductor current, and combines the states of the surrounding STC modules. Through the control circuit, its own working state is adjusted to achieve the stage regulation and phase regulation of the entire system; The STC converter array is formed by connecting M×N groups of STC modules in series at the input and in parallel at the output. The state of each STC module is divided into three types: normal operating state, ON state, and OFF state; When the STC module is in the ON state, the two switching transistors S1 and S2 of the half-bridge at the input end of the power module are always on as wires, and the two switching transistors S3 and S4 of the half-bridge at the output end are always off; when the STC module is in the OFF state, all the switching transistors of the power module are turned off, and the entire power module does not participate in the work; The number of phases of the normal operation of the control system architecture is used to regulate the output efficiency to achieve successive approximation phase regulation. The specific process is as follows: During load switching, the STC modules in the OFF state wait for the enable signal from the previous-phase module. When the enable signal is received, the current module switches to the normal operating state; each STC module in the normal operating state can sample the peak current of the module and compare it with the set upper and lower threshold values. When the peak current is within the hysteresis window, the working state of the module remains unchanged; when the peak current is lower than the lower threshold value, the working state of the module switches to the OFF state; when the peak current is higher than the upper threshold value, check whether the next-phase module is in the OFF state. If so, the working state of the current-phase module remains unchanged, otherwise, a normal operating signal is sent to the next-phase module. By combining the working states of the previous and next-phase modules, the number of phases of the participating working modules is adaptively and successively approximatedly regulated in the above-mentioned way of successively approximatingly regulating the working state of the module.

2. The decentralized successive approximation power management method applicable to the STC converter array according to claim 1, wherein The above-mentioned control of the number of normally operating stages of the STC module is used to regulate the output voltage to achieve successive approximation voltage regulation. The specific process is as follows: During soft start, all power STC modules operate normally. Subsequently, according to the result of the output voltage sampling, the working state of the module is successively approximatedly regulated. Specifically: compare the output voltage with the set upper and lower window threshold values. When the output voltage is within the hysteresis window, the working state of the module remains unchanged; when the output voltage is lower than the lower window threshold value, if the upper-level module is in the ON state, the working state of this module is switched to the ON state, otherwise the working state remains unchanged; when the output voltage is higher than the upper window threshold value, check whether the lower-level module is in the ON state. If so, the working state of this module remains in the ON state, otherwise the working state of this module is switched to a non-ON state; through the above control logic, the number of series working stages is adjusted to adjust the output voltage to the target range.

3. The decentralized successive approximation power management method applicable to the STC converter array according to claim 1, wherein Each STC module independently uses a high-speed current sampling circuit to directly sample the inductor current and simultaneously sample the output voltage. By combining the states of four adjacent STC modules above, below, left, and right, the control circuit obtains the logical working state of a single STC module, and controls the conduction and cutoff of the power transistor of this module according to the logical working state to adjust the working state of this module.

4. The decentralized successive approximation power management method applicable to the STC converter array according to claim 3, characterized in that The control circuit includes a comparator and a logic gate.

5. A computer device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 4.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method according to any one of claims 1 to 4.

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