A novel DC energy collection and management chip and its operation method

Abstract

The present invention proposes a novel DC energy collection and management chip and its operating method, wherein the chip includes: a low-voltage cold start loop, a novel MPPT algorithm energy collection circuit, and an energy management circuit; the low-voltage cold start loop is used to stimulate the internal voltage conversion circuit at a low voltage level, so that the circuit transitions to a normal working state; the novel MPPT algorithm energy collection circuit is used to collect energy, convert the collected ambient energy into electrical energy, and achieve maximum power tracking through a transient enhanced MPPT algorithm circuit; the energy management circuit is used to judge the state of CSTOR, input the judgment result into a control module to generate different enable signals UV and EN, and activate the corresponding management modes Q1 and Q2. The present invention activates the charging management circuit to store excess energy in a secondary energy storage element, a supercapacitor or lithium-ion battery, and activates the DC-DC buck converter to output a stable voltage for the system load, thereby achieving high-efficiency management of DC environmental energy such as photovoltaic and thermoelectric energy.

Description

Technical Field

[0001] The present invention relates to a novel direct current energy collection and management chip and an operating method thereof, belonging to the technical field of energy collection. Background Art

[0002] With the continuous development of Internet of Things (IoT) technology, portable devices, and wireless sensors, how to efficiently power them has become a key issue. As we all know, traditional battery-powered devices have disadvantages such as low energy density, limited battery life, large size, and difficulty in portability. Furthermore, they require regular manual maintenance and replacement. Therefore, a new technology has been proposed to power devices: energy harvesting. Energy harvesting technology collects energy from the environment and converts it into electrical energy. Because environmental energy is sustainable, it reduces the manual intervention and maintenance costs associated with battery-powered devices. Therefore, environmental energy harvesting technology has received increasing attention and research, and is widely used in various fields such as military, agriculture, industry, medicine, and scientific research.

[0003] Currently, common energies that can be harvested from the environment include light, heat, and vibration. Light energy harvesting technology has been developed for a long time and is relatively mature, with a wide range of applications. However, it is limited by the intensity of light. Thermal energy, or thermal gradient energy harvesting, is based on the magnitude of the temperature gradient. The greater the temperature difference, the higher the harvesting efficiency. Wherever there is a temperature difference, there is an energy difference, and its energy generation is rarely affected by external interference. Vibration energy is ubiquitous and can be found everywhere. It has a high energy density and high conversion efficiency, making it easy to harvest. For example, the vibration of the human body when walking, the vibration of the engine when a car is driving, and the vibration of the train body when a train is running, all generate vibration energy, which can serve as an energy source for the energy harvesting system and can be harvested and converted into electricity to power micro-devices.

[0004] Energy harvesting and management circuits are crucial components of energy harvesting technology. Current research focuses on maximizing output power to power the load and efficiently managing energy. Maximum power point tracking (MPPT) circuits typically harvest and utilize weak ambient energy or gradually dissipated energy. However, input power is typically low and significantly affected by the environment. Therefore, MPPT circuits are often incorporated into the design process to maximize the output power. In MPPT circuits, a fast response time, a wide input voltage range for the converter, and precise and efficient voltage tracking are essential to maximize power. Energy harvesting circuits typically have a low starting voltage and cannot be used directly for power supply. Therefore, a low-voltage startup circuit is required, incorporating MOSFETs with low impedance and a low threshold voltage to enable startup even at low input voltages.

[0005] To sum up, the performance of energy harvesting technology is crucial. Low power consumption, high efficiency, high integration and stability are the future development directions of energy harvesting systems. Energy harvesting technology is still in a gradually rising stage in the chip field, and its future prospects have great application scenarios.

[0006] To address this issue, this patent proposes a new DC energy collection and management chip and its operating method. Compared with other energy collection systems, the new maximum power point tracking is adopted, which can achieve higher-speed open-circuit voltage sampling, reduce sampling time, and reduce system losses; add an energy storage system to store excess energy in energy storage elements such as supercapacitors or lithium batteries, integrate charging management and protection circuits, and improve energy utilization; use low-power, high-efficiency BUCK converters to manage energy, and can directly generate stable voltage for the system load. Summary of the Invention

[0007] The present invention aims to solve the technical problems of being able to start the circuit under low input voltage in the existing energy collection system, low energy utilization and long sampling time, and further proposes a new DC energy collection and management chip and its operation method.

[0008] The technical solution adopted by the present invention to solve the above problems is: the present invention proposes a new type of DC energy collection and management chip, comprising:

[0009] Low-voltage cold start loop, new MPPT algorithm energy harvesting circuit and energy management circuit;

[0010] The input end of the low-voltage cold start loop is connected to the DC voltage VIN_DC, and the output end is connected to the MOS transistor MN1, which is used to stimulate the internal voltage conversion circuit at a low voltage level to make the circuit transition to a normal working state;

[0011] The new MPPT algorithm energy harvesting circuit has its input connected to the DC voltage VIN_DC and its output connected to the gates of the power transistors MN2 and MP1. It is used to harvest energy and uses a fixed on-time control mode to stabilize the input voltage, converting ambient energy into electrical energy. Maximum power point tracking is achieved through a transient-enhanced MPPT algorithm circuit.

[0012] The input end of the energy management circuit is connected to the primary energy storage element CSTOR, and the output end is connected to the secondary energy storage element ports VBAT and VOUT respectively. It is used to judge the status of the primary energy storage element CSTOR, input the judgment result into the control module to generate different enable signals UV and EN, and start the corresponding management modes Q1 and Q2 to achieve high-efficiency management of the collected energy.

[0013] Optionally, the low-voltage cold start loop includes a clamping circuit, an optimal oscillator, a clock multiplier, and a logic control circuit;

[0014] The clamping circuit is used to increase the input voltage;

[0015] Optimal oscillator for improved cold start efficiency;

[0016] The clock multiplier is used to increase the gate voltage of the switch tube, enhance the driving ability of the switch tube, and stimulate the circuit to transition to normal working state;

[0017] The logic control circuit is used to generate a POR signal to disable cold start.

[0018] Optional, the new MPPT algorithm energy harvesting circuit includes an energy harvester, an MPPT circuit module, a reference voltage generation module, an undervoltage and overvoltage protection circuit, a COT clock generator, a control circuit, a gate driver, and a zero-crossing detection circuit;

[0019] The energy harvester is used to collect ambient energy and convert the collected ambient energy into electrical energy;

[0020] The MPPT module is used to sample the open circuit to obtain the VMPPT voltage;

[0021] The reference voltage generation module uses the VMPPT voltage as a reference voltage signal;

[0022] The undervoltage and overvoltage protection circuit is used to detect abnormal voltage of the primary energy storage element CSTOR;

[0023] The COT clock generator is used to generate the clock;

[0024] The control circuit is used to compare and detect the voltage of the primary energy storage element CSTOR;

[0025] Gate driver for control signals Φ1 and Φ2

[0026] The zero-crossing detection circuit is used to detect zero inductor current.

[0027] Optionally, the energy management circuit includes a detection module, a control module, a charging management module, a secondary energy storage element, a system load COUT and a buck converter;

[0028] The detection module is used to determine the status of the primary energy storage element CSTOR;

[0029] The control module is used to receive the judgment result and generate enable signals UV and EN through the notification logic;

[0030] The charging management module is used to receive the enable signal UV to execute the Q1 management mode;

[0031] The secondary energy storage element is used to store excess energy exceeding the undervoltage threshold;

[0032] The system load COUT is used to detect the output voltage of the DC-DC buck converter so that the output voltage is equal to the system load COUT;

[0033] The DC-DC buck converter is configured to receive an enable signal EM to execute a Q2 management mode.

[0034] Optionally, the charging management module includes a soft start, a power monitoring module, a constant current-constant voltage control loop, a state control module, an automatic recharging module and a reference circuit;

[0035] Soft start is used to reduce the starting current of the charging management module and achieve smooth starting of the charging management module;

[0036] The power detection module is used to monitor the voltage of the secondary energy storage element in real time during the charging process;

[0037] The constant current-constant voltage control loop is used to charge the secondary energy storage element at a constant current and constant voltage;

[0038] The state control module is used to select the charging mode of the secondary energy storage element;

[0039] The automatic recharging module is used to charge the secondary energy storage element in the standby state;

[0040] The reference circuit is used to provide a reference voltage.

[0041] Optionally, the DC-DC buck converter includes a power stage circuit, a compensation module and an auxiliary module;

[0042] The power stage circuit is used to control the power of the output voltage;

[0043] The compensation module is used to correct the output voltage offset error;

[0044] The auxiliary module is used to perform over-temperature protection and zero-crossing detection ZCD on the system load COUT.

[0045] A novel method for operating a DC energy harvesting and management chip, comprising:

[0046] Step 1: When the initial voltage is insufficient to stimulate the internal circuit, the optimal oscillator in the low-voltage cold start loop generates a clock. The clock multiplier generates a clock square wave, which drives the MOS transistor MN1. The clamp circuit increases the initial input voltage to 2.5V. The logic control circuit generates a POR signal to shut down the cold start, allowing the circuit to transition to normal operation.

[0047] Step 2: Based on the new MPPT algorithm, the energy harvester in the energy harvesting circuit converts ambient energy into electrical energy. The converted electrical energy is used to charge the primary energy storage element CSTOR. The input voltage is stabilized by changing the duty cycle, and the output voltage is boosted to achieve maximum power point tracking.

[0048] Step 3: Based on the detection module in the energy management circuit, the status of the primary energy storage element CSTOR is judged, and the judgment result is input into the control module. The control logic of the control module generates enable signals UV and EN. The enable signal UV is input into the charging management module and the secondary energy storage element to execute the Q1 management mode. The enable signal EN is input into the system load COUT and the buck converter to execute the Q2 management mode, thereby realizing high-efficiency management of the collected energy.

[0049] Optionally, implementing maximum power point tracking in step 2 specifically includes:

[0050] The VMPPT voltage obtained by sampling the open-circuit voltage of the MPPT module is used as the reference voltage signal of the energy harvesting circuit of the new MPPT algorithm. The reference voltage signal is compared with the DC voltage VIN_DC to generate a square wave signal with a certain duty cycle to drive the switching tubes MN2 and MP1 to work. According to the proportional relationship between the input and output voltages and the duty cycle, the duty cycle is changed until VIN_DC is equal to the reference voltage. The zero-crossing detection circuit detects zero inductor current and shuts down the power tube MP to prevent the inductor current from flowing back. The two operating modes of continuous conduction mode (CCM) and discontinuous conduction mode (DCM) are automatically switched to achieve maximum power point tracking.

[0051] Optionally, the Q1 management mode in step 3 specifically includes:

[0052] When the primary energy storage element CSTOR exceeds the undervoltage threshold, the excess energy is stored in the secondary energy storage element, and a unified operational amplifier is used for three-stage charging management, achieving smooth conversion from constant current to constant voltage with low quiescent current. If the voltage of the secondary energy storage element during charging is lower than 3V, it enters trickle mode and uses a small current of 0.1C for charging; when the voltage of the secondary energy storage element is higher than 3V, it uses a constant large current of 1C for charging; when the voltage of the secondary energy storage element is higher than 4.1V, it enters a transition stage and uses a constant voltage charging method. If the charging current decreases to 0.1C, the secondary energy storage element is in standby state and stops charging. When the voltage of the secondary energy storage element drops to 4.05V, it automatically recharges.

[0053] Optionally, the Q2 management mode in step 3 specifically includes:

[0054] The DC-DC buck converter is turned on and designed with three modes: PWM, PFM, and PSM, achieving high energy conversion efficiency under all load conditions. During operation, when the input voltage is lower than the preset output voltage, the DC-DC buck converter enters 100% duty cycle mode, forming a direct path from power supply to inductor to load, making the output voltage close to the preset value for the system load COUT.

[0055] The beneficial effects of the present invention are:

[0056] 1. This invention improves the traditional low-voltage cold-start loop by employing a native NMOS-based power-on reset circuit, an input voltage clamping circuit, and an optimal oscillator frequency setting. A ring oscillator frequency that is too fast will result in insufficient gate drive capability at the power tube, reducing energy transfer efficiency. However, due to the limited conduction of the power tube at the initial startup, a ring oscillator frequency that is too slow will clamp the inductor current and prevent it from changing normally, preventing the output voltage from rising normally. Therefore, an appropriate oscillator frequency setting is required.

[0057] 2. The present invention improves the traditional open-circuit voltage method, adopts a reference voltage generation circuit and a transient enhanced MPPT algorithm circuit, and combines the power stage loop current to charge the input capacitor, which significantly improves the open-circuit voltage sampling rate, making it suitable for the collection of weak energy; at the same time, in the VMPPT voltage selection process, the reference voltage generation circuit is used to first pull up and pull down the input voltage to achieve a smooth transition from sampling to stable state.

[0058] 3. The present invention proposes a new energy management strategy, which efficiently manages the collected energy through an energy management circuit and executes different management modes according to the status of the primary energy storage element: when in the Q1 management mode, the charging management module based on the unified operational amplifier is turned on to store excess energy in the secondary energy storage element supercapacitor or lithium-ion battery; when in the Q2 management mode, the DC-DC buck converter is turned on, and the three modes of PWM / PFM / PSM and 100% duty cycle mode are adopted to improve the energy conversion efficiency and make the output voltage as close as possible to the preset value for the system load. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is a structural diagram of a novel DC energy collection and management chip provided by the present invention;

[0060] Figure 2 This is a schematic diagram of the structure of the new MPPT algorithm energy harvesting circuit provided by the present invention;

[0061] Figure 3 This is a structural diagram of the charging management module provided by the present invention;

[0062] Figure 4A schematic diagram of the structure of the DC-DC buck converter provided by the present invention

[0063] Figure 5 A schematic diagram of an operating method of a novel DC energy collection and management chip provided by the present invention. DETAILED DESCRIPTION

[0064] Specific implementation method 1: Combination Figure 1-4 This embodiment is described as follows. Figure 1 As shown, the structure of a novel DC energy collection and management chip described in this embodiment includes:

[0065] Low-voltage cold start loop, new MPPT algorithm energy harvesting circuit and energy management circuit;

[0066] The input end of the low-voltage cold start loop is connected to the DC voltage VIN_DC, and the output end is connected to the MOS transistor MN1. During the cold start phase, the MOS transistor MP1 is connected in the form of a diode. The cold start circuit can stimulate the internal voltage conversion circuit at a low voltage level, sacrificing efficiency to allow the circuit to transition to normal operation.

[0067] The present invention improves the traditional low-voltage cold start loop by adopting a power-on reset circuit based on a native NMOS transistor, an input voltage clamping circuit, and an optimal oscillator frequency setting. If the ring oscillator frequency is too fast, the gate drive capability of the power tube will be insufficient, reducing energy transmission efficiency. On the other hand, due to the limited conduction degree of the power tube at the initial startup, if the ring oscillator frequency is too slow, the inductor current will be clamped and unable to change normally, and the output voltage will not rise normally. Therefore, an appropriate oscillator frequency setting is required.

[0068] The input end of the new MPPT algorithm energy harvesting circuit is VIN_DC, and the output end is connected to the gate of the power tube MN2 and MP1. One end of the inductor LBOOST is connected to the DC voltage VIN_DC, and the other end is connected to the drain of the power tube MN2 and the drain of MP1 and serves as the SW node. The source of MN2 is grounded, the source of MP1 is connected to one end of the capacitor CSTOR, and the other end of CSTOR is grounded. The output switch control signal of the new MPPT algorithm energy harvesting circuit is connected to the gate of MN2 and MP1 respectively, and adopts a fixed on-time control mode. The switch control signal has a fixed on-time in each cycle. By changing the duty cycle, the input voltage is stabilized, the output is boosted, and maximum power point tracking is achieved.

[0069] like Figure 2As shown in the figure, the new MPPT algorithm energy harvesting circuit mainly consists of two parts: the main power stage circuit and the control stage circuit. It also integrates undervoltage, overvoltage and other protection modules to ensure the safety of the chip in sudden abnormal situations. It adopts a fixed on-time COT control mode. The switch control signal has a fixed on-time in each cycle. COT modulation solves the problems existing in PWM because its on-time is constant and the off-time is controlled by the loop. It has strong adjustability and faster transient response speed. In addition, the switching frequency of COT modulation will change with the change of load conditions. The switching frequency is reduced under light load, which reduces switching loss and improves conversion efficiency. One end of the input capacitor CIN is connected to one end of the inductor LBOOST and is connected to the DC voltage VIN_DC. The other end of the input capacitor CIN is grounded. The other end of LBOOST is connected to the drain of the power tube MN and the drain of MP and serves as the SW node. The source of MN is grounded. The source of MP is connected to one end of the capacitor CSTOR. The other end of CSTOR is grounded. The gates of MN and MP are respectively connected to the switch control signals Φ1 and Φ2 provided by the logic control circuit. The COT clock generator generates a clock connected to the control circuit. The MPPT circuit generates a VMPPT voltage connected to the comparator input of the control circuit. The input of the zero-crossing detection circuit is connected to SW, and the output is to the control circuit to control the gate of MP.

[0070] The function of the new MPPT algorithm energy harvesting circuit in this embodiment is as follows: when sampling the open circuit voltage, the new MPPT algorithm energy harvesting circuit starts PWM control, and the PWM control will automatically generate an inductor current I flowing from the output terminal CSTOR to the input terminal. L To charge the input capacitor, due to the input capacitor charging current I CIN is the input current I PV and the inductor current I L The sum of this reverse I L The open-circuit voltage sampling rate is significantly improved. When VIN_DC is pre-charged to a value close to the open-circuit voltage, the power tubes MN and MP are turned off, and VIN_DC can be stabilized to VOC in a very short time. The VMPPT obtained by sampling and dividing the voltage is used as the loop reference voltage signal of the new MPPT algorithm energy harvesting circuit. It is compared with the DC voltage VIN_DC to generate a square wave signal with a certain duty cycle to drive the switch tube to work. According to the proportional relationship between the input and output voltages and the duty cycle, the off time is changed, and the duty cycle is changed until VIN_DC is equal to the reference voltage. The loop is stable, the zero-crossing detection circuit detects zero inductor current, and turns off the power tube MP to prevent the inductor current from flowing back. The two operating modes of continuous conduction mode (CCM) and discontinuous conduction mode (DCM) can be automatically switched, thereby improving the conversion efficiency of the new MPPT algorithm energy harvesting circuit.

[0071] The present invention improves the traditional open-circuit voltage method by adopting a reference voltage generation circuit and a transient enhanced MPPT algorithm circuit, and combining the power stage loop current to charge the input capacitor, thereby significantly improving the open-circuit voltage sampling rate, making it suitable for the collection of weak energy. At the same time, during the VMPPT voltage selection process, the reference voltage generation circuit is used to first pull up and pull down the input voltage to achieve a smooth transition from sampling to stable state.

[0072] The energy management circuit includes a detection module, a control module, a charge management module, a secondary energy storage element, a system load COUT and a buck converter;

[0073] The energy management circuit input voltage is connected to VSTOR, and the overvoltage (OV) signal generated is connected to the control end of the new MPPT algorithm energy collection circuit. The output signal StandBy is used to display the charging status, and the output signal VBAT is connected to the lithium battery. The charging management module performs charging and protection functions and stores excess energy in the lithium battery; the DC-DC buck converter output switch control signal is connected to the gates of MP3 and MN3 respectively, the source of MP3 is connected to VSTOR, and the drain is connected to the drain of MN3 as the SW point connected to one end of the inductor Lbuck, the other end of Lbuck is connected to the output end of the BUCK buck converter, the output end is connected to one end of the capacitor COUT, and the other end of COUT is grounded; a band gap is used to generate a reference voltage, and an output voltage completion signal BAG_OK signal is provided. The reference current source generates the reference current required by the circuit.

[0074] like Figure 3 As shown, the charging management module includes a soft start, a power monitoring module, a constant current-constant voltage control loop, a state control module, an automatic recharging module, and a reference circuit. The constant current-constant voltage control loop is mainly composed of a feedback loop formed by a unified operational amplifier CMP and power tubes M0 and M1. The battery voltage divider DIV is connected to the positive input terminal of CV, the constant voltage reference VREF_VC generated by the reference circuit is connected to the negative input terminal of CV, the constant current reference VREF_CC generated by the reference circuit is connected to the negative input terminal of CC, and the output terminal is connected to the MOS tube Mp. The drain of Mp is connected to PowerG, the source is connected to the power supply to form a control feedback loop. The input of the operational amplifier MA is connected to the drains of M0 and M1 respectively, and the output is connected to the gate of the MOS tube M2. The drain of M2 is connected to MON, and the source is connected to the drain of M0. The PMOS tube M1 is a power tube that outputs charging current to the battery. The function of M0 is to copy and monitor the current of M1. The ratio of M0 and M1 is 1:1000. The operational amplifier MA modulates the feedback tube M2 to make the VDS of M0 and M1 equal. This can ensure that the current of the M0 branch and the current of the M1 branch are in an accurate 1:1000 ratio.

[0075] like Figure 4As shown, the DC-DC buck converter includes a power stage circuit, an ACOT architecture voltage quadratic control loop, a compensation module and an auxiliary module, wherein the source of MP is connected to the output terminal CSTOR of the DC-DC boost charger, one end of the inductor L is connected to the drain of the power tube MN and the drain of MP and serves as the SW node, the source of MN is grounded, the other end of the inductor L is connected to the output capacitor COUT, the other end of COUT is grounded, and the gates of MN and MP are connected to the switching control signal provided by the control circuit. Adaptive on-time control mode is adopted to achieve constant frequency output in CCM mode and automatic switching between PWM / PFM. The output voltage divider vfb is connected to the negative terminal of the error amplifier EA, the positive terminal of EA is connected to the soft-start reference voltage Vref_ss, the output terminal of EA is connected to the type II compensation circuit, and then to the positive terminal of the comparator COMP. The negative terminal of COMP is connected to the inductor current sampling circuit output Va. Va changes in phase with the inductor current, and the COMP output is connected to the control circuit to generate a switch control signal. The path from Va to the negative terminal of COMP is a fast path, which can quickly respond to output voltage changes and ensure good transient response of the system. The path with the type II compensation network is a slow path, which corrects the output voltage offset error and improves the output voltage adjustment accuracy.

[0076] Specific implementation method 2: Figure 5 As shown, the steps of the operation method of a novel DC energy collection and management chip described in this embodiment include:

[0077] S1: When the initial voltage is insufficient to stimulate the internal circuit, the optimal oscillator in the low-voltage cold start loop generates a clock, which is then multiplied by a clock multiplier to generate a clock square wave. This square wave drives the MOS transistor MN1, and the clamp circuit raises the initial input voltage to 2.5V. The logic control circuit generates a POR signal to shut down the cold start, allowing the circuit to transition to normal operation.

[0078] S2: Based on the new MPPT algorithm, the energy collector in the energy harvesting circuit converts ambient energy into electrical energy, and charges the primary energy storage element CSTOR based on the converted electrical energy. The VMPPT voltage obtained by sampling the open-circuit voltage of the MPPT module is used as the reference voltage signal of the new MPPT algorithm energy harvesting circuit. The reference voltage signal is compared with the DC voltage VIN_DC to generate a square wave signal with a certain duty cycle, which drives the switching tubes MN2 and MP1 to work. According to the proportional relationship between the input and output voltages and the duty cycle, the duty cycle is changed until VIN_DC is equal to the reference voltage. The zero-crossing detection circuit detects zero inductor current, shuts down the power tube MP to prevent the inductor current from flowing back, and automatically switches between the continuous conduction mode CCM and the discontinuous conduction mode DCM to achieve maximum power point tracking.

[0079] S3: Based on the detection module in the energy management circuit, the status of the primary energy storage element CSTOR is judged, and the judgment result is input into the control module. The control logic of the control module generates enable signals UV and EN, and the enable signal UV is input into the charging management module and the secondary energy storage element to execute the Q1 management mode. The enable signal EN is input into the system load COUT and the buck converter to execute the Q2 management mode, thereby realizing high-efficiency management of the collected energy.

[0080] The Q1 management mode includes: when VSTOR exceeds the undervoltage (UV) threshold, the excess energy is stored in the secondary energy storage element, and a unified operational amplifier is used for three-stage charging management, achieving smooth conversion from constant current to constant voltage with low quiescent current. If the battery voltage during charging is lower than 3V, it enters trickle mode and uses a small current of 0.1C for charging; when the voltage of the secondary energy storage element is higher than 3V, it uses a constant large current of 1C for charging; when the voltage of the secondary energy storage element is higher than 4.1V, it enters a transition stage and then uses a constant voltage charging method. If the charging current is reduced to 0.1C, the charger is in standby state and stops charging. In standby state, when the voltage of the secondary energy storage element drops to 4.05V, it automatically recharges, and the StandBy signal displays the charging status. The state control module determines whether to use trickle mode, enter standby mode, or pause charging. In trickle mode, Vref_CC is set to 0.1V, while in normal constant-current-constant-voltage charging, Vref_CC is set to 1V. A reference circuit provides a 1.2V reference voltage for other modules and implements a soft-start at the beginning of charging to avoid inrush current. The power monitoring module detects whether the power supply voltage is valid, while the temperature protection module implements over-temperature protection at 120°C. A unified op amp (CMP) is used for state transitions. By utilizing an unbalanced input differential pair and tail current sharing, a smooth transition from constant current to constant voltage with low quiescent current is achieved, while a unified high-gain loop provides fast regulation.

[0081] The Q2 management mode includes: turning on the DC-DC buck converter and designing three modes: PWM / PFM / PSM, to achieve high energy conversion efficiency under all load conditions. During operation, when the input voltage is lower than the preset output voltage, the DC-DC buck converter enters 100% duty cycle mode, forming a direct path from power supply to inductor to load, so that the output voltage is close to the preset value for the system load COUT.

[0082] During the off-time period, MP turns off and MN turns on, discharging the energy storage inductor and gradually decreasing the inductor current. The inductor current information is transmitted to the PWM comparator via the current sampling module. The EA output voltage Vc is compared with the current sampling signal Va in the PWM comparator. When the sampling current reaches the valley current, the PWM output pulse is sent to the set terminal of the RS flip-flop, turning off MN and turning on MP. The off-time period ends and the on-time period begins. At this point, the adaptive on-time module activates, causing the inductor current to rise. After a certain time, a narrow pulse is output to the clear terminal of the RS flip-flop, signaling the system to enter the off-time period and simultaneously clearing the timer, completing a full control cycle. If the buck converter's load current decreases to a certain level, the hysteresis comparator compares the error amplifier EA output Vc with a reference voltage VREFB. The comparator's output, Sleep, is directly input into the system's logic circuitry to control the power transistor's on / off. During sleep mode, only the bandgap reference, hysteresis comparator, error amplifier, and zero-crossing detection circuit operate; all other circuits are deactivated, significantly reducing system power consumption and improving efficiency.

[0083] The present invention efficiently manages the collected energy through an energy management circuit and executes different management modes according to the status of the primary energy storage element: when in the Q1 management mode, the charging management circuit based on the unified operational amplifier is turned on to store excess energy in the secondary energy storage element, a supercapacitor or lithium-ion battery; when in the Q2 management mode, the DC-DC buck converter is turned on, using three modes of PWM / PFM / PSM and a 100% duty cycle mode to improve energy conversion efficiency and make the output voltage as close as possible to the preset value for system load.

[0084] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement of the above embodiments made according to the technical essence of the present invention, within the spirit and principles of the present invention, without departing from the content of the technical solution of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A new type of DC energy collection and management chip, characterized by: The structure of the novel DC energy collection and management chip includes: Low-voltage cold start loop, new MPPT algorithm energy harvesting circuit and energy management circuit; The input end of the low-voltage cold start loop is connected to the DC voltage VIN_DC, and the output end is connected to the MOS transistor MN1, which is used to stimulate the internal voltage conversion circuit at a low voltage level to transition the circuit to a normal working state. The circuit is a new MPPT algorithm energy collection circuit and energy management circuit. The internal voltage conversion circuit is a power stage circuit composed of passive components, MOS transistor MN1, power transistor MN2 and power transistor MP1; The input end of the novel MPPT algorithm energy harvesting circuit is connected to the DC voltage VIN_DC, and the output end is connected to the gate of the power tube MN2 and MP1, which is used to collect energy and adopt a fixed on-time control mode to stabilize the input voltage, convert the ambient energy into electrical energy, and realize maximum power tracking through the novel MPPT algorithm energy harvesting circuit; The energy management circuit has an input connected to a primary energy storage element CSTOR, and outputs connected to ports VBAT and VOUT of the secondary energy storage element, respectively. The circuit is used to determine the state of the primary energy storage element CSTOR, input the determination result into a control module to generate different enable signals UV and EN, and activate corresponding management modes Q1 and Q2. When the Q1 management mode is activated, a charging management module based on a unified operational amplifier is activated to store excess energy in a secondary energy storage element, a supercapacitor or a lithium-ion battery. When the Q2 management mode is activated, a DC-DC buck converter is activated, employing three modes: PWM / PFM / PSM, and a 100% duty cycle mode, to improve energy conversion efficiency, keep the output voltage as close as possible to a preset value for the system load, and achieve efficient management of collected energy.

2. A novel DC energy collection and management chip according to claim 1, characterized in that: The low-voltage cold start loop includes a clamping circuit, an optimal oscillator, a clock multiplier and a logic control circuit; The clamping circuit is used to increase the input voltage; The optimal oscillator is used to improve cold start efficiency; The clock multiplier is used to increase the gate voltage of the switch tube, enhance the driving ability of the switch tube, and stimulate the circuit to transition to a normal working state; The logic control circuit is used to generate a POR signal to disable cold start.

3. A novel DC energy collection and management chip according to claim 1, characterized in that: The novel MPPT algorithm energy harvesting circuit includes an energy harvester, an MPPT circuit module, a reference voltage generation module, an undervoltage and overvoltage protection circuit, a COT clock generator, a control circuit, a gate driver, and a zero-crossing detection circuit; The energy collector is used to collect environmental energy and convert the collected environmental energy into electrical energy; The MPPT circuit module is used to sample the open circuit to obtain the VMPPT voltage; The reference voltage generating module uses the VMPPT voltage as a reference voltage signal; The undervoltage and overvoltage protection circuit is used to detect abnormalities in the voltage of the primary energy storage element CSTOR; The COT clock generator is used to generate a clock; The control circuit is used to compare and detect the voltage of the primary energy storage element CSTOR; The gate driver is used to control signals Φ1 and Φ2; The zero-crossing detection circuit is used to detect zero inductor current.

4. A novel DC energy collection and management chip according to claim 1, characterized in that: The energy management circuit includes a detection module, a control module, a charging management module, a secondary energy storage element, a system load COUT and a buck converter; The detection module is used to determine the state of the primary energy storage element CSTOR; The control module is used to receive the judgment result and generate enable signals UV and EN through the notification logic; The charging management module is used to receive an enable signal UV to execute a Q1 management mode; The secondary energy storage element is used to store excess energy exceeding the undervoltage threshold; The system load COUT is used to detect the output voltage of the DC-DC buck converter so that the output voltage is equal to the system load COUT; The DC-DC buck converter is configured to receive an enable signal EM to execute a Q2 management mode.

5. A novel DC energy collection and management chip according to claim 4, characterized in that: The charging management module includes a soft start, a power monitoring module, a constant current-constant voltage control loop, a state control module, an automatic recharging module and a reference circuit; The soft start is used to reduce the starting current of the charging management module and achieve smooth starting of the charging management module; The power supply monitoring module is used to monitor the voltage of the secondary energy storage element in real time during the charging process; The constant current-constant voltage control loop is used to charge the secondary energy storage element in a constant current and constant voltage manner; The state control module is used to select a charging mode for the secondary energy storage element; The automatic recharging module is used to charge the secondary energy storage element in the standby state; The reference circuit is used to provide a reference voltage.

6. A novel DC energy collection and management chip according to claim 4, characterized in that: The DC-DC buck converter includes a power stage circuit, a compensation module and an auxiliary module; The power stage circuit is used to control the power of the output voltage; The compensation module is used to correct the output voltage offset error; The auxiliary module is used to perform over-temperature protection and zero-crossing detection ZCD on the system load COUT.

7. A method for operating a novel DC energy collection and management chip, applied to a novel DC energy collection and management chip according to any one of claims 1 to 6, characterized in that: The operation method of the novel DC energy collection and management chip includes the following steps: Step 1: When the initial voltage is insufficient to stimulate the internal circuit, the optimal oscillator in the low-voltage cold start loop generates a clock, which is then multiplied by a clock multiplier to generate a clock square wave. The clock square wave drives the MOS transistor MN1, and the clamp circuit increases the initial input voltage to 2.5V. The logic control circuit generates a POR signal to shut down the cold start, allowing the circuit to transition to normal operation. Step 2: Based on the novel MPPT algorithm, the energy harvester in the energy harvesting circuit converts ambient energy into electrical energy, charges the primary energy storage element CSTOR based on the converted electrical energy, stabilizes the input voltage by changing the duty cycle, and boosts the output voltage to achieve maximum power point tracking. Step 3: Based on the detection module in the energy management circuit, the state of the primary energy storage element CSTOR is judged, and the judgment result is input into the control module. The control logic of the control module generates enable signals UV and EN, and the enable signal UV is input into the charging management module and the secondary energy storage element to execute the Q1 management mode. The enable signal EN is input into the system load COUT and the buck converter to execute the Q2 management mode, thereby realizing high-efficiency management of the collected energy.

8. The method for operating a novel DC energy collection and management chip according to claim 7, characterized in that: The implementation of maximum power point tracking in step 2 specifically includes: The VMPPT voltage obtained by sampling the open-circuit voltage of the MPPT circuit module is used as the reference voltage signal of the new MPPT algorithm energy harvesting circuit. The reference voltage signal is compared with the DC voltage VIN_DC to generate a square wave signal with a certain duty cycle to drive the switching tubes MN2 and MP1 to work. According to the proportional relationship between the input and output voltages and the duty cycle, the duty cycle is changed until VIN_DC is equal to the reference voltage. The zero-crossing detection circuit detects zero inductor current and shuts down the power tube MP to prevent the inductor current from flowing back. The two operating modes of continuous conduction mode (CCM) and discontinuous conduction mode (DCM) are automatically switched to achieve maximum power point tracking.

9. The method for operating a novel DC energy collection and management chip according to claim 7, characterized in that: The Q1 management model in step 3 specifically includes: When the CSTOR of the primary energy storage element exceeds the undervoltage threshold, the excess energy is stored in the secondary energy storage element, and a unified operational amplifier is used for three-stage charging management, achieving smooth conversion from constant current to constant voltage with low quiescent current. If the voltage of the secondary energy storage element during charging is lower than 3V, it enters trickle mode and uses a small current of 0.1C for charging; when the voltage of the secondary energy storage element is higher than 3V, it uses a constant large current of 1C for charging; when the voltage of the secondary energy storage element is higher than 4.1V, it enters a transition stage and uses a constant voltage charging method. If the charging current decreases to 0.1C, the secondary energy storage element enters standby mode and stops charging. When the voltage of the secondary energy storage element drops to 4.05V, it automatically recharges.

10. The method for operating a novel DC energy collection and management chip according to claim 7, characterized in that: The Q2 management model in step 3 specifically includes: The DC-DC buck converter is turned on and designed with three modes: PWM, PFM, and PSM, achieving high energy conversion efficiency under all load conditions. During operation, when the input voltage is lower than the preset output voltage, the DC-DC buck converter enters 100% duty cycle mode, forming a direct path from power supply to inductor to load, making the output voltage close to the preset value for the system load COUT.

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