Energy collection circuit and equipment based on current ripple tracking and phase self-adaption

Abstract

The invention provides an energy collection circuit and device based on current ripple tracking and phase self-adaption, and the circuit comprises a generator input end which is used for being connected with an electromagnetic generator; the sampling unit is used for collecting output current of the electromagnetic generator and outputting sampling current; the reference current generation unit is used for sensing the output voltage of the electromagnetic generator and generating a reference current according to the output voltage; the three-mode controller is used for extracting current ripple envelope information from the reference current, judging the working mode of the circuit according to the current ripple envelope information and the sampling current, and generating a control signal according to the working mode; the power conversion unit is used for adjusting input impedance and an input current phase according to the control signal so as to realize conjugate matching; the energy storage unit is used for storing the electric energy adjusted by the power conversion unit; and the energy output unit is used for outputting the electric energy stored by the energy storage unit.

Description

Energy harvesting circuit and device based on current ripple tracking and phase adaptation Technical Field

[0001] This application relates to the field of power harvesting technology, and in particular to a power harvesting circuit and device based on current ripple tracking and phase adaptation. Background Technology

[0002] With the increasing demand for long-term, maintenance-free power supplies from IoT nodes, environmental monitoring sensors, and wearable devices, electromagnetic vibration energy harvesting technology has become an important direction for supplying low-power loads. The equivalent source impedance of an electromagnetic generator contains a significant reactive component, and this reactance varies significantly with the excitation frequency and environmental conditions. When the output reactance is on the same order of magnitude as the equivalent resistance, traditional resistance matching methods cannot achieve maximum power transfer. In this case, conjugate impedance matching must be considered to simultaneously adjust the amplitude and phase, so that the source voltage and current are in phase to obtain maximum power.

[0003] In related technologies, common practices include using resistance matching or control strategies based on zero crossover / polarity detection, as well as power converters using two-quadrant or simple rectifier topologies. These methods work well when the generator inductive reactance is negligible, but when the inductive reactance is high or the frequency drift is significant, it is difficult to meet the conjugate matching requirements because the input current phase cannot be flexibly adjusted. Summary of the Invention

[0004] In view of this, it is necessary to provide an energy harvesting circuit and device based on current ripple tracking and phase adaptation, which can at least overcome one of the above defects.

[0005] In a first aspect, embodiments of this application provide an energy harvesting circuit based on current ripple tracking and phase adaptation, connected to an electromagnetic generator. The circuit includes: a generator input terminal for connecting to the electromagnetic generator; a sampling unit for acquiring the output current of the electromagnetic generator and outputting a sampled current; a reference current generation unit for sensing the output voltage of the electromagnetic generator and generating a reference current based on the output voltage; and a three-mode controller for extracting current ripple envelope information from the reference current, determining the operating mode of the circuit based on the current ripple envelope information and the sampled current, and generating control signals based on the operating mode. The system includes: a signal; a power conversion unit for adjusting the input impedance and input current phase according to the control signal to achieve conjugate matching; an energy storage unit for storing the electrical energy regulated by the power conversion unit; and an energy output unit for outputting the electrical energy stored in the energy storage unit. The three-mode controller employs a constant on-time modulation strategy. When the sampled current equals the reference current, the control circuit enters the first mode and maintains a constant on-time. After the on-time ends, it automatically switches to the second or third mode based on the deviation direction between the sampled current and the reference current, achieving current ripple envelope tracking and phase adaptation without the need for zero-crossover detection.

[0006] In one embodiment, the power conversion unit includes a full-bridge AC-DC conversion circuit; the full-bridge AC-DC conversion circuit includes a first upper bridge arm switch, a second upper bridge arm switch, a first lower bridge arm switch, and a second lower bridge arm switch, wherein the first upper bridge arm switch and the second upper bridge arm switch are PMOS transistors, and the first lower bridge arm switch and the second lower bridge arm switch are NMOS transistors.

[0007] In one embodiment, when the circuit is in the first mode, both the first lower bridge arm switch and the second lower bridge arm switch are turned on, the input voltage is zero, and energy is not transferred to the energy output unit; when the circuit is in the second mode, both the first upper bridge arm switch and the second lower bridge arm switch are turned on, the input voltage equals the output voltage, the energy of the electromagnetic generator is transferred to the energy output unit, and the input current decreases; when the circuit is in the third mode, both the first lower bridge arm switch and the second upper bridge arm switch are turned on, the input voltage equals the negative output voltage, the energy of the energy output unit is transferred to the equivalent inductance of the electromagnetic generator, and the input current increases.

[0008] In one embodiment, the three-mode controller applies a constant on-time modulation strategy; when the sampled current is equal to the reference current, the circuit is controlled to enter the first mode and maintain a constant on-time; after the constant on-time ends: if the sampled current is greater than the reference current, the circuit switches to the second mode; if the sampled current is less than the reference current, the circuit switches to the third mode; if the sampled current is equal to the reference current again, the circuit returns to the first mode.

[0009] In one embodiment, the three-modal controller includes: a first comparator, a second comparator, a first rising edge delay circuit, a second rising edge delay circuit, a first inverter, and a second inverter; the first comparator and the second comparator are used to compare the sampled current with the reference current; the first rising edge delay circuit and the second rising edge delay circuit are used to generate the constant on-time; the first inverter and the second inverter are used for signal shaping and logic output; wherein, the first comparator, the first rising edge delay circuit, and the first inverter constitute a first control path; the second comparator, the second rising edge delay circuit, and the second inverter constitute a second control path; the first control path and the second control path form a complementary structure so that the first control path and the second control path do not output control signals simultaneously.

[0010] In one embodiment, the circuit further includes a dead time generator connected between the tri-mode controller and the power conversion unit; the dead time generator forms a dead time to prevent shoot-through of the upper and lower bridge arms by performing different delay processing on the rising and falling edges of the switching signal; wherein the dead time length is set to be greater than the turn-off time of the PMOS transistor and the NMOS transistor, and less than 10% of the constant on time.

[0011] In one embodiment, the dead time generator includes: a first AND gate and a second AND gate, respectively used to process a first switch signal and a second switch signal; a first RC delay unit connected to the input of the first AND gate; and a second RC delay unit connected to the input of the second AND gate. The dead time generator generates a dead time to prevent shoot-through between the upper and lower bridge arms by performing different delay processing on the rising and falling edges of the first switch signal and the second switch signal.

[0012] In one embodiment, the reference current generation unit includes an auxiliary winding and a filtering circuit; the auxiliary winding is wound around the main winding of the electromagnetic generator and is used to sense a voltage signal in phase with the main winding; the filtering circuit is a low-pass filter and is used to filter out high-frequency noise in the signal output by the auxiliary winding to generate a stable reference current.

[0013] In one embodiment, the sampling unit is provided with a common-mode voltage filter at its input terminal; the common-mode voltage filter is used to suppress common-mode interference in the input signal; the cutoff frequency of the common-mode filter is higher than the switching frequency of the power conversion unit.

[0014] In a second aspect, embodiments of this application provide an electronic device, including: an electromagnetic generator; and an energy harvesting circuit based on current ripple tracking and phase adaptation as described in the first aspect.

[0015] The energy harvesting circuit and electronic device based on current ripple tracking and phase adaptation provided in this application introduce a current ripple envelope tracking and three-mode constant on-time control strategy. This enables automatic conjugate matching and phase synchronization with the internal impedance of the electromagnetic generator without relying on a zero-crossover detection circuit and a processor such as an MCU, thereby significantly improving the power conversion efficiency of micro-energy harvesting. At the same time, the circuit adopts a full hardware architecture to implement the core control function, which greatly reduces the static power consumption and overall complexity of the system. This allows it to provide more stable and longer-lasting power support for low-power wireless sensing nodes, wearable devices and other electronic devices under limited environmental vibration energy. Attached Figure Description

[0016] Figure 1 is a schematic diagram of an energy harvesting circuit based on current ripple tracking and phase adaptation provided in an embodiment of this application.

[0017] Figure 2 is a schematic diagram of a module of an energy harvesting circuit based on current ripple tracking and phase adaptation provided in another embodiment of this application.

[0018] Figure 3 is a schematic diagram of a three-modal controller circuit provided in an embodiment of this application.

[0019] Figure 4 is a schematic diagram of the equivalent impedance network for electromagnetic vibration energy harvesting provided in an embodiment of this application.

[0020] Figure 5 is a schematic diagram of the voltage and current waveforms of the equivalent circuit under conjugate matching provided in an embodiment of this application.

[0021] Figure 6 is a schematic diagram of a conjugate impedance matching circuit provided in an embodiment of this application.

[0022] Figure 7a is a waveform diagram of the working mode provided in an embodiment of this application.

[0023] Figure 7b is a diagram showing the transition of working modes provided in an embodiment of this application.

[0024] Figure 8 is a schematic diagram of the equivalent circuit in the first mode provided in an embodiment of this application.

[0025] Figure 9 is a comparison diagram of voltage polarity and optimal input voltage waveform provided in an embodiment of this application.

[0026] Figure 10 is a schematic diagram of an electronic device provided in an embodiment of this application.

[0027] Figure 11a is a schematic diagram of the dead time generation circuit provided in an embodiment of this application.

[0028] Figure 11b is a waveform signal schematic diagram of a dead time generation circuit provided in an embodiment of this application.

[0029] Key Component Symbol Explanation: Energy Harvesting Circuit Based on Current Ripple Tracking and Phase Adaptation 10 Generator Input Terminal 11 Sampling Unit 12 Reference Current Generation Unit 13 Three-Mode Controller 14 Power Conversion Unit 15 Energy Storage Unit 16 Energy Output Unit 17 Electronic Equipment 20 Electromagnetic Generator 21 Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of the invention described below can be combined with each other as long as they do not conflict with each other.

[0031] It should be noted that, in the embodiments of this application, "at least one" refers to one or more, and "more than one" refers to two or more. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0032] It should be noted that in the embodiments of this application, the terms "first," "second," etc., are used only for descriptive purposes and should not be construed as indicating or implying relative importance, nor as indicating or implying order. Features specified as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0033] Based on the embodiments described in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] With the increasing demand for long-term, maintenance-free power supplies from IoT nodes, environmental monitoring sensors, and wearable devices, electromagnetic vibration energy harvesting technology has become an important direction for supplying low-power loads. The equivalent source impedance of an electromagnetic generator contains a significant reactive component, which varies considerably with the excitation frequency and environmental conditions. When the output reactance is on the same order of magnitude as the equivalent resistance, traditional resistance matching methods cannot achieve maximum power transfer. In this case, conjugate impedance matching must be considered to simultaneously adjust the amplitude and phase, thereby ensuring that the source voltage and current are in phase to obtain maximum power. However, existing implementation methods often rely on complex detection (such as precise zero-crossing determination and polarity detection) or MCU-based software control, leading to a significant increase in implementation cost and control energy consumption, which is unfavorable for vibration energy harvesting scenarios where the energy itself is extremely limited.

[0035] In related technologies, common approaches include using resistance matching or control strategies based on zero-crossing / polarity detection, as well as power converters employing two-quadrant or simple rectifier topologies. These methods work well when the generator's inductive reactance is negligible, but when inductive reactance is dominant or frequency drift is significant, they struggle to meet conjugate matching requirements due to the inability to flexibly adjust the input current phase. On the other hand, using MCUs or digital controllers can achieve finer phase and impedance regulation, but at the expense of system energy efficiency and simplicity—in many practical applications, control consumption may even exceed the energy harvested. Therefore, reducing the implementation complexity and power consumption of conjugate matching circuits, and achieving phase adaptation and four-quadrant current control without the need for high-power processors, has become a pressing technical challenge in this field.

[0036] The energy harvesting circuit and device based on current ripple tracking and phase adaptation provided in this application introduces a current ripple envelope tracking and three-mode constant on-time control strategy. This enables automatic conjugate matching and phase synchronization with the internal impedance of the electromagnetic generator without relying on a zero-crossover detection circuit and a processor such as an MCU, thereby significantly improving the power conversion efficiency of micro-energy harvesting. At the same time, the circuit adopts a full hardware architecture to implement the core control function, which greatly reduces the static power consumption and overall complexity of the system. This allows it to provide more stable and longer-lasting power support for low-power wireless sensing nodes, wearable devices and other electronic devices under limited environmental vibration energy.

[0037] Figure 1 is a schematic diagram of a current ripple tracking and phase adaptation energy harvesting circuit according to an embodiment of this application. As shown in Figure 1, the current ripple tracking and phase adaptation energy harvesting circuit 10 includes at least the following components: a generator input terminal 11, a sampling unit 12, a reference current generation unit 13, a three-mode controller 14, a power conversion unit 15, an energy storage unit 16, and an energy output unit 17. Please also refer to Figure 2, which is a schematic diagram of another embodiment of this application of a current ripple tracking and phase adaptation energy harvesting circuit.

[0038] In this embodiment, the generator input terminal 11 is used to connect to the electromagnetic generator 21. The sampling unit 12 is used to collect the output current of the electromagnetic generator 21 and output a sampled current signal. The reference current generation unit 13 is used to sense the output voltage of the electromagnetic generator and generate a reference current signal based on the output voltage. The three-mode controller 14 is used to extract current ripple envelope information from the reference current, determine the circuit's operating mode based on the current ripple envelope information and the sampled current, and generate a control signal based on the operating mode. The power conversion unit 15 is used to adjust the input impedance and input current phase according to the control signal to achieve conjugate matching. The energy storage unit 16 is used to store the electrical energy regulated by the power conversion unit 15. The energy output unit 17 is used to output the electrical energy stored in the energy storage unit 16.

[0039] Among them, the three-mode controller 14 adopts a constant on-time modulation strategy. When the sampled current is equal to the reference current, the control circuit enters the first mode and maintains a constant on-time. After the on-time ends, it automatically switches to the second or third mode according to the deviation direction between the sampled current and the reference current, so as to realize current ripple envelope tracking and phase adaptation without the need for zero crossover detection.

[0040] Specifically, in actual operation, the three-modal controller 14 coordinates with various functional units to achieve current ripple tracking and phase adaptation as follows: the sampling unit 12 samples the output current and output voltage of the generator 21 in real time. The sampling can be performed by a sampling resistor or a Hall sensor and input to the three-modal controller 14 after anti-aliasing filtering; the three-modal controller 14 performs envelope extraction on the sampled current signal; the reference current generation unit 13 generates a reference current according to the sampled voltage (or the amplitude / average of the voltage) according to a preset mapping relationship or control law (e.g., according to the ratio of instantaneous voltage to desired power or lookup table mapping), and the reference current serves as the comparison benchmark within the three-modal controller 14. The three-modal controller 14 adopts a constant-on-time modulation strategy: when the sampled current equals the reference current, the control path is activated. The power conversion unit 15 is placed in the first mode (equivalent no-load / holding state) and maintained for a constant on-time. ;when After completion, the controller determines whether to switch to the second or third mode based on the deviation direction between the current sampled current and the reference current. If the sampled current is greater than the reference current, it switches to the second mode (enabling energy transfer from the generator to the energy output / storage unit, with the input current showing a decreasing trend), achieving the specified voltage polarity and conduction path by activating switches such as the first upper bridge arm and the second lower bridge arm. If the sampled current is less than the reference current, it switches to the third mode (enabling energy feedback from the energy storage unit or conversion circuit to the generator's equivalent inductance, with the input current showing an increasing trend), achieving the opposite voltage polarity and energy loop by activating the first lower bridge arm and the second upper bridge arm. The design of alternating first / second / third modes and constant conduction time allows for fine-tuning of the input current waveform slope and phase by changing the conduction start time and subsequent mode selection, thus achieving phase adaptation and approximate conjugate matching without relying on voltage zero crossover or polarity detection. To ensure safe and stable operation of the device, a dead-time generation circuit, reverse connection protection, and over / under voltage detection circuits are connected in parallel in the control path, and the three-mode controller is adjustable during tracking. Step size, sampling rate, and mode switching threshold are used to constrain and control energy consumption and achieve optimization.

[0041] It is understood that the specific implementation of the above modules does not limit the scope of protection of this invention: current and voltage sampling can be performed using analog peak hold or digitized and processed in a low-power MCU / dedicated mixed-signal controller; current ripple envelope tracking can be achieved by analog integral control or by digital algorithms in a low-speed MCU (such as a PID control strategy based on constant on-time); the specific time constant, comparator threshold, and mapping relationship of the reference current generation of the constant on-time strategy can be optimized according to the equivalent impedance and operating spectrum of the generator; the device type of the full-bridge switch (PMOS / NMOS, bidirectional transistor, MOSFET, or IGBT) and the power conversion topology (full-bridge, half-bridge, bidirectional buck-boost, etc.) can be replaced according to the application scenario without departing from the concept of this invention; the first, second, and third modes can correspond to no-load hold, positive energy extraction, and feedback / regeneration behavior, respectively, in different implementations. Thus, this invention achieves a balance between hardware complexity and control energy consumption, enabling near-conjugate matching with extremely low control overhead under conditions of micro-vibration and weak excitation, and facilitating its application in maintenance-free low-power power supply scenarios such as power transmission line inspection, wearable sensing, and long-term environmental monitoring.

[0042] In this embodiment, the power conversion unit 15 includes a full-bridge AC-DC conversion circuit; the full-bridge AC-DC conversion circuit includes a first upper bridge arm switch. Second upper bridge arm switch tube First lower bridge arm switch tube Second lower bridge arm switch tube The first upper bridge arm switch tube Second upper bridge arm switch tube It is a PMOS transistor, the first lower bridge arm switching transistor. Second lower bridge arm switch tube It is an NMOS transistor.

[0043] In this embodiment, when the circuit is in the first mode, the first lower bridge arm switching transistor... With the second lower bridge arm switch tube All are on, input voltage When the voltage is zero, no energy is transferred to the energy output unit 17. When the circuit is in the second mode, the first upper bridge arm switching transistor... Second lower bridge arm switch tube On, input voltage equal to output voltage Energy from the electromagnetic generator 21 is transferred to the energy output unit 17, and the input current decreases. When the circuit is in the third mode, the first lower bridge arm switch transistor... Second upper bridge arm switch tube On, input voltage equal to negative output voltage The energy from the energy output unit 17 is transferred to the equivalent inductance of the electromagnetic generator 21, and the input current increases.

[0044] Specifically, please refer to Figure 6, which is a schematic diagram of a conjugate impedance matching circuit provided in an embodiment of this application. The full-bridge AC-DC converter circuit is driven by the control signals (i.e., S1 and S2) output by the three-mode controller 14, and can switch between three operating modes to regulate the input voltage. polarity and input current The direction is used to simulate the RC input impedance required to achieve conjugate matching. In the first mode, the first lower bridge arm switch... With the second lower bridge arm switch tube At the same time, the circuit is turned on, short-circuiting the input terminal to ground. ≈0, energy is not transferred between the generator and the output terminal; in the second mode, the first upper bridge arm switching transistor... With the second lower bridge arm switch tube Conduction occurs, forming a circuit from the generator through the inductor, Output energy storage capacitor , The return loop, at this time Equal to positive output voltage Energy is transferred from the generator to the output terminal; in the third mode, the first lower bridge arm switch transistor... With the second upper bridge arm switch tube When the circuit is turned on, it forms a circuit from the output energy storage capacitor. through Generator inductance The returned loop is now equal to the negative output voltage. Energy can be instantly fed back from the output end to the generator inductor or the current can be rapidly established.

[0045] Understandably, using a full-bridge topology with PMOS transistors forming the upper arm and NMOS transistors forming the lower arm simplifies the high-side drive design compared to a topology using only NMOS transistors (e.g., eliminating the need for a bootstrap circuit), which is beneficial for reducing drive losses and complexity in low-voltage, low-power scenarios. More importantly, this four-switch full-bridge structure supports input voltage... Switching between positive, zero, and negative voltage levels, and input current. The bidirectional flow (four-quadrant operation) provides the necessary hardware foundation for flexibly and dynamically adjusting the phase (i.e., imaginary part characteristic) of the equivalent input impedance presented by the converter to the generator, enabling it to overcome the functional limitations of traditional rectifiers and actively track and meet the phase conditions required for conjugate matching.

[0046] In this embodiment, the three-mode controller employs a constant on-time modulation strategy. Specifically, when the sampled current equals the reference current, the control circuit enters the first mode and maintains a constant on-time. After the constant on-time ends: if the sampled current is greater than the reference current, it switches to the second mode; if the sampled current is less than the reference current, it switches to the third mode; and if the sampled current equals the reference current again, it returns to the first mode.

[0047] Specifically, please refer to Figures 7a and 7b together. Figure 7a is a waveform diagram of the operating mode provided in an embodiment of this application. In Figure 7a, the voltage signal at the generator input terminal 11 changes between three levels through the switching control of the AC-DC converter 15. Since the internal resistance of the electromagnetic generator exhibits inductive reactance characteristics, the equivalent capacitive reactance of the converter input impedance is used to cancel the output inductive reactance of the electromagnetic generator. Therefore, its average voltage Vavg and the reference current Iref show a certain phase difference as shown in Figure 7a. Figure 7b is a transition diagram of the operating mode provided in an embodiment of this application. The current comparator contained inside the three-mode controller continuously samples the current. With reference current The comparison is performed. When the two are equal, the controller triggers a timing period determined by the RC delay circuit, during which the circuit is forced to operate in the first mode. After the timing ends, the controller latches the comparator's output state: if the comparator indicates... If the output drive signal causes the circuit to enter the second mode, then the output drive signal will cause the circuit to enter the second mode; otherwise, if the output drive signal is not output, the circuit will enter the second mode. Then it enters the third mode. Afterward, the controller continues to monitor the current comparison result, and once it detects again... If the current mode is terminated immediately, the first mode is re-entered and a new timing cycle is started, thus forming a closed-loop control sequence that combines event triggering and time triggering.

[0048] Understandably, the core of the control strategy lies in transforming the complex input voltage phase tracking problem into determining the instantaneous deviation direction between the easily sampled input current ripple and a given reference signal. This mode-switching mechanism based on the current deviation direction essentially achieves automatic capture of the optimal polarity switching point of the input voltage without relying on any direct detection circuitry for the zero-crossing point of the voltage waveform. Therefore, it can effectively overcome the phase shift caused by generator inductance ( This eliminates the detection and current tracking challenges posed by the system, and the entire judgment and switching logic can be implemented in pure hardware using low-power analog comparators and digital gate circuits. This ensures that while pursuing high energy extraction efficiency, the system maintains extremely low control power consumption, perfectly meeting the fundamental needs of micro-energy harvesting scenarios.

[0049] In this embodiment, the three-modal controller 14 includes: a first comparator CMP1, a second comparator CMP2, a first rising edge delay circuit, a second rising edge delay circuit, a first inverter U1, and a second inverter U2. The first comparator CMP1 and the second comparator CMP2 are used to compare the sampled current with a reference current. The first rising edge delay circuit and the second rising edge delay circuit are used to generate a constant on-time. The first inverter U1 and the second inverter U2 are used for signal shaping and logic output. The first comparator CMP1, the first rising edge delay circuit, and the first inverter U1 constitute a first control path. The second comparator CMP2, the second rising edge delay circuit, and the second inverter U2 constitute a second control path. The first control path and the second control path form a complementary structure so that the first control path and the second control path do not output control signals simultaneously.

[0050] Specifically, please refer to Figure 3, which is a schematic diagram of a three-mode controller circuit provided in an embodiment of this application. In this circuit, the inverting input of the first comparator CMP1 and the non-inverting input of the second comparator CMP2 jointly receive the sampled current signal. The non-inverting input of the first comparator CMP1 and the inverting input of the second comparator CMP2 both receive the reference current. Signal. This cross-input configuration makes the output logic of the two comparators complementary: when When CMP1 outputs a low level, CMP2 outputs a high level; when At this time, CMP1 outputs a high level, and CMP2 outputs a low level. The outputs of the two comparators are respectively connected to the corresponding rising edge delay circuit (usually composed of resistors, capacitors, and diodes, such as an RC circuit with diodes to achieve rising edge triggering and fast discharge). This circuit is configured to generate a fixed-width positive pulse only when a low-to-high transition (rising edge) of the input signal is detected. This pulse width corresponds to the constant on-time. This pulse signal is then shaped and logically inverted by a subsequent inverter (U1 or U2), ultimately outputting two switch control signals, S1 and S2, to drive the corresponding bridge arms in the power conversion unit. Due to the symmetrical and complementary design of the two paths, it is ensured that S1 and S2 will never be simultaneously active (e.g., high level), thus eliminating the possibility of shoot-through between the upper and lower bridge arms of the full-bridge circuit at the logic level.

[0051] Understandably, the hardware circuit implements complex tri-modal control logic using a minimalist set of analog and digital components (two comparators, two RC delay units, and two inverters). It cleverly integrates current tracking, timing decision-making, and logic interlocking functions into a single unit, requiring no software intervention or clock synchronization throughout, demonstrating significant advantages in high reliability, low latency, and ultra-low static power consumption. In particular, by adjusting the values ​​of resistors or capacitors in the delay circuit, the constant on-time can be precisely set. This achieves an optimal balance between current ripple amplitude and switching frequency, enabling the energy harvesting circuit to adapt to different vibration frequencies and generator parameters. This all-hardware solution perfectly meets the stringent power consumption requirements of micro-energy harvesting scenarios and is key to achieving efficient, autonomous, and long-term maintenance-free energy harvesting.

[0052] In this embodiment, the circuit further includes a dead-time generator connected between the tri-mode controller 14 and the power conversion unit 15. The dead-time generator generates a dead time to prevent shoot-through of the upper and lower bridge arms by applying different delays to the rising and falling edges of the switching signal. The dead-time length is set to be greater than the turn-off time of the PMOS and NMOS transistors, but less than 10% of the constant on-time.

[0053] Specifically, the core function of the dead-time generator is to perform edge delay processing on the raw switching signals (i.e., S1 and S2) from the tri-mode controller 14 to generate the final signal driving the power conversion unit switching transistors. Its basic principle is to introduce asymmetrical delays to the rising and falling edges of the signal using an RC delay unit: typically, to prevent transistor shoot-through, it is necessary to ensure that the upper transistor can only turn on after the lower transistor of one bridge arm is completely turned off, and vice versa. Therefore, the RC network is usually configured to appropriately delay the "turn-on edges" (such as the edges of the upper and lower transistors turning on) of the effective drive signal, while the "turn-off edges" have virtually no delay or minimal delay, thus artificially inserting a "both are off" safety interval, i.e., dead time, between consecutive switching actions.

[0054] Understandably, precise setting of the dead time is crucial. An excessively long dead time unnecessarily shortens the effective on-time, reducing switching efficiency and potentially affecting current tracking accuracy; an excessively short dead time is insufficient to cover the actual turn-off delay of the switch, failing to reliably prevent shoot-through. Setting it to be greater than the maximum turn-off time of the switch (PMOS / NMOS) ensures safety redundancy, while limiting it to less than the constant on-time (…). The 10% dead time is allocated to ensure that the dead time has a negligible impact on the time proportion of the main operating modes (especially the second and third modes of energy transfer), thereby maximizing the efficient operation of the circuit while ensuring absolute safety. This hardware-implemented dead time management mechanism is also a key component for achieving low-power, high-reliability, and autonomous operation of the entire system. It does not require processor intervention in timing and has a rapid and stable response.

[0055] Please refer to Figures 11a and 11b together. Figure 11a is a connection diagram of a dead-time generation circuit provided in an embodiment of this application. Figure 11b is a waveform signal diagram of a dead-time generation circuit provided in an embodiment of this application.

[0056] In this embodiment, the dead-time generator includes a first AND gate AND1 and a second AND gate AND2, used to process a first switch signal and a second switch signal, respectively. A first RC delay unit is included, connected to the input of the first AND gate AND1. A second RC delay unit is connected to the input of the second AND gate. The dead-time generator generates a dead time to prevent shoot-through between the upper and lower bridge arms by applying different delays to the rising and falling edges of the first and second switch signals.

[0057] Specifically, the original pulse modulation signal (PWM_in) is processed in two paths: one path passes through a delay network composed of resistor Rd1 and capacitor Cd1, generating a small symmetrical delay T1, before being input to the second AND gate AND2 for shaping, and the output is used as the lower bridge arm drive signal PWM_L; the other path enters a rising edge delay path composed of the first AND gate AND1 and its specially designed RC network (resistor Rd2 and capacitor Cd2) at its front end. When the rising edge of PWM_in arrives, the lower input terminal of the first AND gate AND1 immediately becomes high, but its upper input terminal is connected to capacitor Cd2, and the voltage needs to be slowly increased by charging through Rd2 until it exceeds the logic threshold of the AND gate. Only then does the output PWM_H of the first AND gate AND1 jump to a high level. This process generates an adjustable rising edge delay T2 (T2>T1). When the falling edge of PWM_in arrives, the lower input terminal of the first AND gate AND1 is immediately pulled low, causing PWM_H to become low almost synchronously, with no significant delay in the falling edge. By carefully setting the parameters of Rd2 and Cd2, the delay time T2 can be precisely controlled, thereby setting the required dead time.

[0058] Understandably, this pure hardware dead-time generation scheme has significant advantages. First, it achieves reliable asymmetric delay control using extremely simple analog and digital components (two AND gates and four RC components), requiring no processor or complex state machine intervention. Its own power consumption is extremely low, perfectly meeting the ultra-low power constraints of micro-energy harvesting systems. Second, the design cleverly binds the dead-time to the critical "turn-on" action (rising edge), naturally generating a delay through RC charging. This ensures that in any switching cycle, the lower transistor drive (PWM_L) is always effective before the upper transistor drive (PWM_H), thus safely guiding the turn-on sequence of the lower transistor turning on first and the upper transistor turning on later. Conversely, during turn-off, the upper transistor drive can be almost immediately removed, achieving a safe sequence of the upper transistor turning off first and the lower transistor turning off later. This mechanism proactively eliminates shoot-through risk at the logic level. Finally, the length of the dead time can be flexibly and stably adjusted through the parameters of passive components, which facilitates the optimization and matching of the actual turn-off time of different types of switching transistors. Under the premise of ensuring absolute safety, the negative impact of the dead time on power transmission efficiency is minimized, which is an important guarantee for achieving high reliability, high efficiency and fully autonomous operation of the entire system.

[0059] In this embodiment, the reference current generation unit 13 includes an auxiliary winding and a filtering circuit. The auxiliary winding is wound around the main winding of the electromagnetic generator 21 and is used to sense a voltage signal in phase with the main winding. The filtering circuit is a low-pass filter used to filter out high-frequency noise in the signal output from the auxiliary winding and generate a stable reference current. .

[0060] Specifically, the auxiliary winding, through tight magnetic coupling, can reproduce the induced voltage across the main winding with almost no phase difference. The induced voltage signal first passes through a passive pre-filtering network composed of resistors and capacitors to attenuate excessively high-frequency spikes. Subsequently, the signal is fed into a multiple-feedback (MFB) active second-order low-pass filter. This filter is carefully designed with a cutoff frequency set much higher than the ambient vibration frequency. However, this is located far below the switching frequency of the power conversion unit. This design fully preserves the fundamental sinusoidal voltage information characterizing the energy source, while completely filtering out high-frequency switching noise and stray interference coupled to the auxiliary winding by the switching action, ultimately outputting a pure, smooth, and consistent signal. A strictly in-phase sinusoidal voltage. This voltage signal, through a precise transconductance circuit or scaling circuit, can generate a reference current signal with appropriate amplitude and ideal waveform. .

[0061] Understandably, using an auxiliary winding to indirectly obtain voltage information, rather than sampling directly on the main power circuit, avoids introducing additional series impedance or losses into the sampling circuit, thus ensuring the efficiency of the main circuit. The MFB type active filter is chosen because it provides a steep out-of-band attenuation characteristic while maintaining good phase linearity within the passband, which is crucial for generating a filter without additional phase distortion. Crucially, this ensures the accuracy of the reference for subsequent phase-matching control. The power consumption of the entire reference current generation path is designed to be extremely low, perfectly meeting the ultra-low power consumption constraints of micro-energy harvesting systems.

[0062] In this embodiment, the sampling unit 12 has a common-mode voltage filter at its input. The common-mode voltage filter is used to suppress common-mode interference in the input signal. The cutoff frequency of the common-mode filter is higher than the switching frequency of the power conversion unit.

[0063] Specifically, the current sampling circuit in the sampling unit typically employs a differential amplification architecture based on a high-precision operational amplifier. A common-mode voltage filter, consisting of a common-mode choke and / or a matched RC network, is connected before each of its two differential input terminals. This filter presents high impedance to common-mode interference signals of equal magnitude and in the same direction, thus significantly attenuating them; while allowing differential-mode signals of equal magnitude and in opposite directions (i.e., the current signal to be sampled) to pass through with almost no loss. By appropriately selecting the parameters of the filter components, its cutoff frequency (… The frequency is set at a frequency approximately one order of magnitude higher than the switching frequency (fsw) of the power conversion unit. This effectively suppresses common-mode noise caused by the switching frequency and its harmonics, while ensuring that the bandwidth of the differential-mode signal containing current ripple information is not compressed, thus achieving high signal-to-noise ratio and high fidelity current sampling.

[0064] Understandably, in switching power converters, rapid voltage transitions generate significant common-mode noise current through parasitic capacitance, severely interfering with sensitive current sampling signals. Setting a common-mode voltage filter is an economical and effective means of noise suppression. Setting its cutoff frequency above the switching frequency ensures that the closed-loop control bandwidth of the current loop is unrestricted, a prerequisite for achieving fast and accurate current ripple tracking control. Simultaneously, the selected operational amplifier itself has low quiescent current and high common-mode rejection ratio, working in conjunction with the common-mode filter to jointly guarantee the accuracy of the sampling signal and the control performance of the system with extremely low power consumption.

[0065] In this embodiment, please refer to Figures 2 and 3. Figure 2 shows a modular schematic diagram of another embodiment of this application. Its energy harvesting circuit based on current ripple tracking and phase adaptation includes core modules such as a generator input, sampling unit, reference current generation unit, three-mode controller, power conversion unit, energy storage unit, and energy output unit. It also clearly indicates several auxiliary modules for engineering implementation: including a frequency / amplitude estimation module, an analog-to-digital conversion and anti-aliasing filter module, a dead-time generation and switch drive interface, protection circuits (overvoltage / undervoltage / overcurrent / reverse connection), and input filter inductors and bypass capacitors in the power path. In Figure 2, the modules coordinate with each other through signal lines and control lines: the current signal acquired by the sampling unit... With voltage signal After anti-aliasing filtering, the signal is input to the three-mode controller 14, which simultaneously sends the signal to the three-mode controller 14 to achieve envelope tracking of the reference current signal. The reference current generation unit takes the sampled voltage or its amplitude / average as input and generates the reference current according to a preset mapping or algorithm. The signal is then fed into a three-mode controller. The switching control signal output from the three-mode controller is generated by a dead-time generation unit to form a bridge arm drive signal, which then drives the full bridge or other power conversion topologies. This achieves adjustment of the equivalent input impedance and the phase of the input current, thereby completing approximate conjugate matching and maximum power point tracking (MPPT). Simultaneously, the frequency estimation module estimates the vibration angular frequency. Feedback is sent to the reference current generation unit and the three-mode controller 14 to adjust the reference and envelope detection parameters during frequency drift; the protection circuit can directly command the three-mode controller to enter sleep / disconnect mode to protect the device and memory unit in abnormal conditions.

[0066] Specifically, Figure 3 illustrates the circuit implementation of the three-modal controller in this embodiment. The circuit consists of a first comparator, a second comparator, a first rising edge delay circuit, a second rising edge delay circuit, a first inverter, a second inverter, and complementary logic. It works in conjunction with a dead-time generation circuit to drive the four switches of the power conversion unit. The sampled current and the reference current are input to the first and second comparators, respectively, to generate comparison outputs. When the sampled current and the reference current are equal (the comparator outputs form a specific combination state), the first rising edge delay circuit or the second rising edge delay circuit is triggered, thereby generating a constant on-time. The pulse is shaped by the first / second inverter and output as the turn-on command for the bridge arm. After the constant on-time expires, the real-time output of the comparator (the magnitude of the sampled current relative to the reference current) determines whether the first control path or the second control path continues to maintain the next on-state: if the sampled current is greater than the reference current, the second mode output is enabled first (corresponding to the bridge arm combination that enables energy extraction in the figure); if the sampled current is less than the reference current, the third mode output is enabled first (corresponding to the bridge arm combination that enables feedback / boost input current in the figure). The first and second control paths are complementary, and the logic and dead-time generation unit ensure that the two paths will not output simultaneously, causing the upper and lower bridge arms to shoot through; the dead-time generation circuit applies a controllable delay to the rising edge and falling edge respectively, and the delay value is set to be greater than the turn-off time of the PMOS / NMOS device used and less than the constant on-time. The value is 10% (or adjusted according to the specific device characteristics) to ensure safety without significantly affecting the conduction period and control accuracy. Figure 3 also shows the filtering / hysteresis components for signal shaping and the short pulse suppression circuit for jitter reduction to avoid frequent mode switching caused by sampling noise.

[0067] It is understood that the module division and circuit implementation shown in Figures 2 and 3 above are preferred embodiments, and their specific structures, device types, and implementation parameters can be replaced in various equivalent ways while still falling within the protection scope of this invention. The comparator and delay circuit shown in Figure 3 can be constructed using discrete analog devices, or the corresponding functions can be implemented in the peripherals of a dedicated mixed-signal control chip or a low-power MCU; the full-bridge device can be PMOS / NMOS, bidirectional MOSFET, or other reversible switching elements, and the power conversion topology can also be replaced with a half-bridge, bidirectional buck-boost, etc., to adapt to different voltage / power levels; constant on-time Parameters such as comparison threshold, dead time, sampling rate, and mode switching threshold can be determined based on the equivalent parameters of the specific electromagnetic generator. , Engineering optimizations are performed based on the application scenarios (vibration spectrum, load characteristics). The above substitutions and parameter adjustments are variations that can be achieved by those skilled in the art in conventional testing and design, and should not be considered as limitations on the scope of protection of this invention.

[0068] Please refer to Figures 4 and 5 together. Figure 4 is a schematic diagram of the equivalent impedance network for electromagnetic vibration energy harvesting provided in an embodiment of this application. Figure 5 is a schematic diagram of the voltage and current waveforms of the equivalent circuit under conjugate matching provided in an embodiment of this application.

[0069] In this embodiment, the electromagnetic vibration energy generator can be modeled using the Thevenin equivalent circuit, as shown in Figure 4. This equivalent model consists of an ideal voltage source V... EH Equivalent impedance Z EH With the input impedance Z of the converter in Composition, in which V EH Z represents the induced voltage of the coil. EH From the equivalent output resistance R EH With output inductor L EH Series connection, Z in The equivalent input resistance R of the converter in With input bypass / output capacitor C in It is connected in series. For ease of analysis, V EH Considered to have an angular frequency of ω vib Peak value is V p The sinusoidal excitation has the following mathematical expression: The equivalent impedance and the load impedance are respectively and From this equivalent circuit, the expression for the input active power at the converter terminal can be obtained:

[0070] In theory, when the conjugate matching condition is satisfied Maximum power transfer can be achieved at this time. and The matching conditions can be obtained directly from the form. and Under this matching condition, the loop is equivalent to a pure resistor, and the total equivalent resistance is... The corresponding optimal input current, interface voltage, and maximum input power can be expressed as:

[0071] The phase amplitude and phase are determined by , and A decision can be written as

[0072]

[0073] in Indicates induced voltage relative interface voltage The leading phase angle. Figure 5 shows the phase angle under the conjugate matching condition. , and The schematic waveform.

[0074] Specifically, when the generator's equivalent resistance Much larger than the resistance term (Right now When phase shift occurs... The source voltage can be approximated as zero. With interface voltage Essentially in phase, this can be detected by... Zero crossover is used to determine the interface voltage. The polarity is determined and the converter is controlled accordingly; at this low inductive reactance-dominated operating point, polarity determination based on zero voltage crossover has the advantages of simple implementation and low control overhead. However, in inductive reactance-dominated or inductive reactance-resistance-on-order (i.e., when the inductive reactance is on the same order of magnitude as the resistance) In the case of (or greater), It cannot be ignored and varies with the vibration frequency Obvious change - at this time and There is a significant phase difference, and it depends solely on Zero crossover cannot be reliably determined The instantaneous polarity of the capacitor can lead to misjudgments of the converter's switching timing and conduction polarity, reducing the efficiency of instantaneous active power acquisition and increasing the complexity of control implementation. Furthermore, due to the matching capacitor... The theoretical value is When the vibration frequency drifts or the equivalent parameters change, the static passive matching element is difficult to maintain conjugate matching, which causes the harvestable power to drop significantly with the frequency shift. Therefore, in practical engineering, it is necessary to adjust the equivalent input impedance and input current phase of the converter to compensate for the above phase and impedance mismatch, so as to ensure that the maximum power transmission is approximately achieved in a wide bandwidth or dynamic environment.

[0075] It is understood that the above equivalent models and formulas are the basis for idealized analysis and design. In specific implementation, various equivalent substitutions and engineering implementations can be made without departing from the concept of this invention: sampling can use current sampling resistors or Hall sensors in conjunction with anti-aliasing filtering and ADC digitization; current envelope extraction can be achieved by analog peak hold / rectification + low-pass filtering, or by low-speed digital algorithms (sliding window peak / valley detection, exponential weighted averaging, or short-time analysis methods); phase compensation and impedance adjustment can be achieved by the duty cycle / constant on-time strategy and mode switching of controllable switches, or by combining variable active / passive components; in addition, device parasitic parameters, drive dead time, protection circuits (overvoltage / undervoltage / overcurrent / reverse connection) and low-power sleep mechanisms are all necessary supplements for engineering implementation, but do not constitute a limitation on the scope of protection claimed in this application. In summary, this embodiment illustrates the influence of inductive reactance on phase and matching through theoretical modeling, and provides a design basis for subsequent control strategies based on current ripple envelope tracking and phase adaptation.

[0076] Please refer to Figures 8 and 9 together. Figure 8 is a schematic diagram of the equivalent circuit in the first mode provided by an embodiment of this application. Figure 9 is a comparison diagram of voltage polarity and optimal input voltage waveform provided by an embodiment of this application.

[0077] In this embodiment, the polarity switching point is the optimal switching point required by the circuit. Due to the conduction time T... on Much smaller than the period T of the sine wave vib For the kth switching cycle, when the circuit is in the "first mode", the circuit can be equivalent to the s-domain circuit model shown in Figure 8.

[0078] Let the starting time of the k-th switching cycle be . The initial value of the input current at this time is denoted as... Then there is

[0079] During this period, the time-domain expression of the induced voltage source VEH is:

[0080] Specifically, expressing the above equation in the Laplace domain, we get: Expression in the s domain (for) Perform Laplace transform and use (for parameter offset):

[0081] According to Kirchhoff's voltage law (for equivalent circuits: With series And the converter input circuit), the expression for the input current in the s-domain can be derived as follows:

[0082] Performing an inverse Laplace transform on the above equation yields the input current. The analytical expression in the time domain (in the form of...) And with (Timed from the starting point)

[0083] The substitutions and parameters used in the formula are defined as follows:

[0084] Because this embodiment uses constant on-time control, the controller is at time... A logical judgment will be executed once: comparing the magnitude of the reference current with the sampled input current, and then constructing the constructor.

[0085] Note Always satisfied ,Right now Therefore, the sign judgment can be transformed into the difference quotient. The sign determination. If the conduction time is constant. If it is small enough, it can be approximated by the derivative. To determine the sign of the difference quotient. Calculation yields (the limit). The derivative is expressed as:

[0086] As can be seen from the above equation, the derivative The symbol is composed of Decision. Based on the derivative sign, this embodiment constructs a voltage polarity determination quantity:

[0087] Based on this, the controller decides whether to switch to the second mode (forward decimation) or the third mode (feedback / boost) in the next step, thereby fine-tuning the slope and phase of the input current through mode selection and a constant on-time mechanism. The simulation / illustration results shown in Figure 9 indicate that the controller is based on The voltage polarity sequence obtained from the determination Phase-to-the-theoretical optimal input voltage By maintaining consistency, the feasibility of the proposed control strategy in determining the polarity of the input voltage and achieving phase adaptation without the need for direct zero-crossover detection is verified from a mathematical and theoretical perspective.

[0088] Understandably, the above derivation and judgment are based on several approximations and engineering premises: First, using derivatives... The condition for the approximate difference quotient to hold is a constant on-time. The transient time constant of the circuit must be sufficiently small relative to the vibration period; secondly, actual circuits have sampling noise, comparator hysteresis, device on-state voltage drop, parasitic parameters, and dead time, all of which will affect... The actual time-domain waveform deviates from the ideal analytical expression described above. Therefore, in engineering implementation, appropriate thresholds, filtering, or hysteresis need to be introduced for the determination (to avoid frequent mode switching caused by noise). Furthermore, this application provides a quantitative description of the theoretical analytical structure of the input current over time and its phase relationship, which is helpful for designing constant on-time. The comparison threshold, sampling rate, and three-mode switching strategy provide guiding engineering parameter selection criteria. Finally, although this embodiment demonstrates the theoretical basis of the control strategy through analytical derivation, in practical implementation, the above-mentioned judgment and switching control can be equivalently implemented using analog circuits (comparator + delay / inverting / dead-time circuits) or peripherals and software logic of a low-power mixed-signal controller / MCU. Furthermore, frequency estimation, envelope smoothing, and MPPT modules can be combined to adjust parameters online, thereby improving robustness and adapting to different electromagnetic generator parameters and operating conditions. All the above-mentioned alternative implementations and engineering optimizations fall within the protection scope of this invention.

[0089] Figure 10 shows an electronic device 20 provided in an embodiment of this application. As shown in Figure 10, the electronic device 20 includes at least the following components: an electromagnetic generator 21 and an energy harvesting circuit 10 based on current ripple tracking and phase adaptation.

[0090] Furthermore, the electronic device 20 in the above embodiments can also be implemented as an assembly (device group) composed of multiple devices. Each device constituting the device group can possess some or all of the functions or functional blocks of the electronic device 20 in the above embodiments. As a device group, it is sufficient to have all the functions or functional blocks of the electronic device 20.

[0091] In this embodiment, the electronic device 20 can be any low-power device that relies on micro-energy harvesting technology to achieve self-powering or extended battery life, including but not limited to: wireless sensor nodes for environmental monitoring (such as temperature, humidity, light, and vibration monitoring), wearable health monitoring devices (such as smart bracelets and body temperature patches), self-powered sensors in the Industrial Internet of Things, and implantable medical devices. The high efficiency and low self-power consumption of the energy harvesting circuit 10 enable such devices to break free from dependence on traditional batteries or greatly extend their maintenance cycle, achieving long-term, autonomous operation.

[0092] The energy harvesting circuit and device based on current ripple tracking and phase adaptation provided in this application introduces a current ripple envelope tracking and three-mode constant on-time control strategy. This enables automatic conjugate matching and phase synchronization with the internal impedance of the electromagnetic generator without relying on a zero-crossover detection circuit and a processor such as an MCU, thereby significantly improving the power conversion efficiency of micro-energy harvesting. At the same time, the circuit adopts a full hardware architecture to implement the core control function, which greatly reduces the static power consumption and overall complexity of the system. This allows it to provide more stable and longer-lasting power support for low-power wireless sensing nodes, wearable devices and other electronic devices under limited environmental vibration energy.

[0093] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An energy harvesting circuit based on current ripple tracking and phase adaptation, connected to an electromagnetic generator, characterized in that, The circuit includes: a generator input terminal for connecting to the electromagnetic generator; a sampling unit for acquiring the output current of the electromagnetic generator and outputting a sampled current; a reference current generation unit for sensing the output voltage of the electromagnetic generator and generating a reference current based on the output voltage; a three-mode controller for extracting current ripple envelope information from the reference current, determining the operating mode of the circuit based on the current ripple envelope information and the sampled current, and generating a control signal based on the operating mode; a power conversion unit for adjusting the input impedance and input current phase according to the control signal to achieve conjugate matching; an energy storage unit for storing electrical energy regulated by the power conversion unit; and an energy output unit for outputting the electrical energy stored in the energy storage unit. The three-mode controller employs a constant on-time modulation strategy. When the sampled current equals the reference current, the control circuit enters the first mode and maintains a constant on-time. After the on-time ends, it automatically switches to the second or third mode based on the deviation direction between the sampled current and the reference current, achieving current ripple envelope tracking and phase adaptation without the need for zero-crossover detection.

2. The energy harvesting circuit based on current ripple tracking and phase adaptation according to claim 1, characterized in that, The power conversion unit includes a full-bridge AC-DC conversion circuit; the full-bridge AC-DC conversion circuit includes a first upper bridge arm switch, a second upper bridge arm switch, a first lower bridge arm switch, and a second lower bridge arm switch, wherein the first upper bridge arm switch and the second upper bridge arm switch are PMOS transistors, and the first lower bridge arm switch and the second lower bridge arm switch are NMOS transistors.

3. The energy harvesting circuit based on current ripple tracking and phase adaptation according to claim 2, characterized in that, When the circuit is in the first mode, both the first lower bridge arm switch and the second lower bridge arm switch are turned on, the input voltage is zero, and energy is not transferred to the energy output unit; when the circuit is in the second mode, both the first upper bridge arm switch and the second lower bridge arm switch are turned on, the input voltage is equal to the output voltage, the energy of the electromagnetic generator is transferred to the energy output unit, and the input current decreases. When the circuit is in the third mode, the first lower bridge arm switch and the second upper bridge arm switch are turned on, the input voltage is equal to the negative output voltage, the energy of the energy output unit is transferred to the equivalent inductance of the electromagnetic generator, and the input current increases.

4. The energy harvesting circuit based on current ripple tracking and phase adaptation according to claim 3, characterized in that, The three-mode controller employs a constant on-time modulation strategy; when the sampled current is equal to the reference current, the circuit is controlled to enter the first mode and maintain a constant on-time. After the constant conduction time ends: if the sampled current is greater than the reference current, switch to the second mode; if the sampled current is less than the reference current, switch to the third mode; if the sampled current is equal to the reference current again, return to the first mode.

5. The energy harvesting circuit based on current ripple tracking and phase adaptation according to claim 4, characterized in that, The three-mode controller includes: a first comparator, a second comparator, a first rising edge delay circuit, a second rising edge delay circuit, a first inverter, and a second inverter; the first comparator and the second comparator are used to compare the sampled current with the reference current; the first rising edge delay circuit and the second rising edge delay circuit are used to generate the constant on-time; the first inverter and the second inverter are used for signal shaping and logic output; wherein, the first comparator, the first rising edge delay circuit, and the first inverter constitute a first control path; the second comparator, the second rising edge delay circuit, and the second inverter constitute a second control path; the first control path and the second control path form a complementary structure so that the first control path and the second control path do not output control signals simultaneously.

6. The energy harvesting circuit based on current ripple tracking and phase adaptation according to claim 5, characterized in that, The circuit further includes a dead time generator connected between the tri-mode controller and the power conversion unit. The dead time generator generates a dead time to prevent shoot-through of the upper and lower bridge arms by performing different delay processing on the rising and falling edges of the switching signal. The dead time length is set to be greater than the turn-off time of the PMOS transistor and the NMOS transistor, and less than 10% of the constant on time.

7. The energy harvesting circuit based on current ripple tracking and phase adaptation according to claim 6, characterized in that, The dead time generator includes: a first AND gate and a second AND gate, used to process the first switch signal and the second switch signal, respectively; a first RC delay unit connected to the input of the first AND gate; and a second RC delay unit connected to the input of the second AND gate. The dead time generator generates a dead time to prevent shoot-through between the upper and lower bridge arms by performing different delay processing on the rising and falling edges of the first switch signal and the second switch signal.

8. The energy harvesting circuit based on current ripple tracking and phase adaptation according to claim 1, characterized in that, The reference current generation unit includes an auxiliary winding and a filtering circuit; the auxiliary winding is wound around the main winding of the electromagnetic generator and is used to sense a voltage signal in phase with the main winding; the filtering circuit is a low-pass filter, used to filter out high-frequency noise in the signal output by the auxiliary winding and generate a stable reference current.

9. The energy harvesting circuit based on current ripple tracking and phase adaptation according to claim 1, characterized in that, The sampling unit is equipped with a common-mode voltage filter at its input terminal; the common-mode voltage filter is used to suppress common-mode interference in the input signal; the cutoff frequency of the common-mode filter is higher than the switching frequency of the power conversion unit.

10. An electronic device, characterized in that, include: Electromagnetic generator; And, the energy harvesting circuit based on current ripple tracking and phase adaptation as described in any one of claims 1 to 9.

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