Novel direct current energy collection and management chip and operation method thereof

Abstract

The invention provides a novel direct-current energy collection and management chip and an operation method thereof. The chip comprises 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 for exciting an internal voltage conversion circuit at a low voltage level, so that the circuit is transited to a normal working state; the novel MPPT algorithm energy collection circuit is used for collecting energy, collecting and converting environment energy into electric energy, and realizing maximum power tracking through the transient enhanced MPPT algorithm circuit; and the energy management circuit is used for judging the state of the CSTOR, inputting a judgment result into the control module to generate different enable signals UV and EN, and starting corresponding management modes Q1 and Q2. According to the invention, the charging management circuit is started to store excess energy in a secondary energy storage element super capacitor or a lithium ion battery, and the DC-DC step-down converter is started to output a stable voltage for a system load, so that high-efficiency management of photovoltaic, thermoelectric and other direct-current environment energy is realized.

Description

Technical Field

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

[0002] With the continuous development of Internet of Things technology, portable devices and wireless sensors, how to efficiently power them has become a key issue. As we all know, traditional battery power supply has the disadvantages of low energy density, limited battery life, large size, and difficulty in carrying, and requires regular manual maintenance and replacement. Therefore, people have proposed a new technology to power the equipment, namely energy harvesting technology. Energy harvesting technology collects energy in the environment and then converts the collected energy into electrical energy. Since the energy in the environment is sustainable, it reduces the manual intervention and maintenance costs associated with battery power supply. Therefore, environmental energy harvesting technology has received more and more attention and research, and has been widely used in military, agriculture, industry, medical, scientific research and other fields.

[0003] At present, the energy that can be collected in common environments includes: light energy, thermal energy and vibration energy. Among them, light energy collection technology has been developed for a long time and the technology is relatively mature, and it has many application fields, but it is affected by the light intensity factor, which limits its application scope. Thermal energy, also known as thermal gradient energy collection technology, is based on the size of the temperature gradient. The greater the temperature difference, the higher the collection efficiency. As long as there is a temperature difference, there will be an energy difference, and its energy generation is rarely affected by external interference. Vibration energy is everywhere and can be seen everywhere. It has high energy density and high conversion efficiency and is easy to collect. For example, the vibration of the human body when walking, the vibration of the engine when the car is driving, the vibration of the car body when the train is driving, etc., will generate vibration energy, which can be used as the energy source of the energy collection system, and can be collected and converted into electrical energy to power micro devices.

[0004] Energy harvesting circuits and energy management circuits are important components of energy harvesting technology. How to maximize the output power to provide power to the load and how to efficiently manage energy are the current research focuses. In the maximum power tracking circuit, generally weak energy in the environment or gradually lost energy is collected and utilized. However, the input power is generally low and is greatly affected by the environment. Therefore, the MPPT circuit is generally used in the design process to maximize the input power output. In the MPPT circuit, the response speed is as fast as possible, the voltage input to the converter has a wide input range, and the accuracy and efficiency of voltage tracking are all guarantees of maximum power. The starting voltage of the energy harvesting circuit is generally low and cannot be used directly for power supply. A low-voltage startup circuit needs to be designed, and a MOS tube with low impedance and low threshold voltage is added to realize the startup circuit under low input voltage conditions.

[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 direction of energy harvesting systems. Energy harvesting technology is still in a gradual rising stage in the chip field, and its future prospects have great application scenarios.

[0006] To this end, this patent proposes a new type of DC energy collection and management chip and its operating method. Compared with other energy collection systems, the new maximum power point tracking 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 a low-power, high-efficiency BUCK converter to manage energy, which can directly generate a 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 novel 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, including:

[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 tube 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 input end of the new 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 use a fixed on-time control mode to stabilize the input voltage, convert the environmental energy into electrical energy, and realize maximum power tracking through the 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, which is used to judge the state of the primary energy storage element CSTOR, input the judgment result to the control module to generate different enable signals UV and EN, and start the corresponding management modes Q1 and Q2 to achieve efficient 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 clamp circuit is used to increase the input voltage;

[0015] Optimum 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 a normal working state;

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

[0018] Optionally, 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] The gate driver is used to control the signals Φ1 and Φ2

[0026] The zero-crossing detection circuit is used to detect the 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 state 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 to make the output voltage equal to the system load COUT;

[0033] The DC-DC buck converter is used for receiving the enable signal EM to execute the 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 realize 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 operation method of a DC energy collection and management chip, comprising:

[0046] Step 1: When the initial voltage is insufficient to stimulate the internal circuit to work, the optimal oscillator in the low-voltage cold start loop generates a clock, and the clock square wave is obtained through the clock multiplier. The MOS tube MN1 is driven based on the clock square wave, and the initial input voltage is increased to 2.5V by the clamp circuit. The logic control circuit generates a POR signal to turn off the cold start, so that the circuit transitions to a normal working state;

[0047] Step 2: Based on the new MPPT algorithm, the energy collector in the energy collection 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, boosts the output voltage, and realizes maximum power point tracking;

[0048] 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, so as to realize efficient 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 new MPPT algorithm energy collection 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 switch 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 off the power tube MP to prevent the inductor current from flowing back. The two working 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 to achieve a smooth conversion from constant current to constant voltage with low static current. If the voltage of the secondary energy storage element during charging is lower than 3V, it enters the 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 the transition stage and uses a constant voltage charging method. If the charging current is reduced to 0.1C, the secondary energy storage element is in standby mode 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] Turn on the DC-DC buck converter and design three modes of 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 the 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.

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

[0056] 1. The present invention improves the traditional low-voltage cold start loop, adopts a power-on reset circuit based on Native NMOS tube, an input voltage clamping circuit and an optimal oscillator frequency setting. If the frequency of the ring oscillator is too fast, the gate driving capability of the power tube will be insufficient and the energy transmission efficiency will be reduced. However, since the conduction degree of the power tube at the initial startup is limited, the ring oscillator frequency is too slow, which will cause the inductor current to be clamped and unable to change normally, and the output voltage cannot rise normally. Therefore, a suitable oscillator frequency setting is performed.

[0057] 2. The present invention improves the traditional open-circuit voltage method, adopts a reference voltage generating circuit, 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 generating 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 manages the collected energy efficiently through an energy management circuit and executes different management modes according to the state of the primary energy storage element: when the Q1 management mode is in progress, 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 the Q2 management mode is in progress, 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 to the preset value as possible for the system load. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0060] Figure 2 A schematic diagram of the structure of a novel MPPT algorithm energy collection circuit provided by the present invention;

[0061] Figure 3 A schematic diagram of the structure 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 To illustrate this embodiment, 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 tube MN1. During the cold start stage, the MOS tube MP1 is connected in the form of a diode. The cold start circuit can excite the internal voltage conversion circuit at a low voltage level, sacrificing efficiency to make the circuit transition to the normal operation stage.

[0067] The present invention improves the traditional low-voltage cold start loop, adopts a power-on reset circuit based on a Native NMOS tube, an input voltage clamping circuit and an optimal oscillator frequency setting. If the frequency of the ring oscillator is too fast, the gate driving capability of the power tube will be insufficient and the energy transmission efficiency will be reduced. However, since the conduction degree of the power tube at the initial startup is limited, the ring oscillator frequency is too slow, which will cause the inductor current to be clamped and unable to change normally, and the output voltage cannot rise normally. Therefore, a suitable oscillator frequency setting is performed.

[0068] The input end VIN_DC of the new MPPT algorithm energy collection circuit and the output end are connected to the gates of the power tubes 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 a 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 collection circuit is connected to the gates of MN2 and MP1 respectively, and a fixed on-time control mode is adopted. The switch control signal has a fixed on-time in each cycle. The input voltage is stabilized by changing the duty cycle, the output is boosted, and the maximum power point tracking is achieved.

[0069] like Figure 2As shown in the figure, the new MPPT algorithm energy harvesting circuit is mainly composed 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 losses and improves conversion efficiency. One end of the input capacitor CIN is connected to one end of the inductor LBOOST and 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 a 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 zero-crossing detection circuit input 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: 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 sampling rate of the open-circuit voltage is significantly improved. When VIN_DC is pre-charged to a voltage 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 energy collection circuit of the new MPPT algorithm. 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 shutdown 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 the power tube MP is turned off to prevent the inductor current from flowing back. The two working modes of continuous conduction mode CCM and discontinuous conduction mode DCM can be automatically switched to improve the conversion efficiency of the energy collection circuit of the new MPPT algorithm.

[0071] The present invention improves the traditional open-circuit voltage method, adopts a reference voltage generating circuit, 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 generating 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 charging 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 to store 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 a SW point connected to one end of the inductor Lbuck, and the other end of Lbuck is connected to the output end of the BUCK buck converter, and 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, and a reference current source generates a 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, wherein 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, the output terminal is connected to the MOS tube Mp, and 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 to M1 is 1:1000. The operational amplifier MA modulates the feedback tube M2 to make the VDS of M0 and M1 equal, which 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 a 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, the gates of MN and MP are connected to the switch control signal provided by the control circuit, and an adaptive on-time control mode is adopted to realize constant frequency output in CCM mode and realize automatic switching of 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, connected to the positive terminal of the comparator COMP, the negative terminal of COMP is connected to the inductor current sampling circuit output Va, Va and the inductor current change in phase, and the COMP output is connected to the control circuit to generate a switch control signal; 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, while 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 to work, the optimal oscillator in the low-voltage cold start loop generates a clock, and the clock square wave is obtained through the clock multiplier. The MOS tube MN1 is driven based on the clock square wave, and the initial input voltage is increased to 2.5V by the clamp circuit. The logic control circuit generates a POR signal to turn off the cold start, so that the circuit transitions to a normal working state;

[0078] S2: Based on the new MPPT algorithm, the energy collector in the energy collection circuit converts ambient energy into electrical energy, charges the primary energy storage element CSTOR based on the converted electrical energy, and uses the VMPPT voltage obtained by sampling the open-circuit voltage of the MPPT module as the reference voltage signal of the new MPPT algorithm energy collection 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 switch 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 off 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 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, so as to realize efficient 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, and a smooth conversion from constant current to constant voltage is achieved with low quiescent current. If the battery voltage during charging is lower than 3V, it enters the 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, a constant large current of 1C is used for charging; when the voltage of the secondary energy storage element is higher than 4.1V, a transition phase is carried out, and then a constant voltage charging method is used. If the charging current is reduced to 0.1C, the charger is in standby state and stops charging. In the standby state, when the voltage of the secondary energy storage element drops to 4.05V, it is automatically recharged, and the StandBy signal displays the charging status. Whether to apply trickle mode, whether it is in standby mode, and whether charging should be suspended are all determined by the state control module. In trickle mode, Vref_CC is set to 0.1V. In normal constant current-constant voltage charging mode, Vref_CC is set to 1V. The reference circuit provides a reference voltage of 1.2V for other modules and implements soft start at the beginning of charging to avoid surge charging current at the beginning of charging. The power monitoring module is responsible for detecting whether the power supply voltage is valid. The temperature protection module implements 120℃ over-temperature protection. The unified op amp CMP is used to realize state conversion. The unbalanced input differential pair and tail current sharing can realize low static current constant current-constant voltage smooth transition, and fast adjustment is performed with a unified high-gain loop.

[0081] The Q2 management mode includes: turning on the DC-DC buck converter, designing three modes of PWM / PFM / PSM, and 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 the 100% duty cycle mode, forming a direct path of power supply-inductor-load, so that the output voltage is close to the preset value for the system load COUT.

[0082] During the off time period, MP is off, MN is on, the energy storage inductor is discharged, and the inductor current gradually decreases. The inductor current information is transmitted to the PWM comparator through the current sampling module, and the EA output voltage Vc is compared with the current sampling signal Va in the PWM comparator. When the sampling current touches the valley current, the PWM output pulse is sent to the RS trigger set end, thereby driving the MN to be turned off and the MP to be turned on. The off period ends and enters the on period. At this time, the adaptive on time module works, and the inductor current rises. When the timing passes a certain time, a narrow pulse is output to the RS trigger clear end, and the system enters the off period. At the same time, the timer is cleared to complete a complete control cycle. If the load current of the Buck converter is reduced to a certain extent, the output Vc of the error amplifier EA is compared with a reference voltage VREFB through the hysteresis comparator. The output Sleep of the comparator is directly input into the logic circuit of the system to control the switch of the power tube. In addition, during the SLEEP mode, only the bandgap reference source, hysteresis comparator, error amplifier and zero-crossing detection circuit work, and other circuits stop working, which can greatly reduce the system power consumption and improve efficiency.

[0083] The present invention manages the collected energy efficiently through an energy management circuit, and executes different management modes according to the state 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 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 to the preset value as possible for the system load.

[0084] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A new type of DC energy collection and management chip, characterized in that: 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 tube 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; The input end of the novel MPPT algorithm energy collection 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 adopts a fixed on-time control mode to stabilize the input voltage, convert the environmental energy collection into electrical energy, and realize maximum power tracking through the transient enhanced MPPT algorithm circuit; The input end of the energy management circuit is connected to the primary energy storage element CSTOR, and the output end is respectively connected to the secondary energy storage element ports VBAT and VOUT, and is used to judge the state of the primary energy storage element CSTOR, input the judgment result to the control module to generate different enable signals UV and EN, and start the corresponding management modes Q1 and Q2 to 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 shut down 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 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 abnormal 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 inductance 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 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 used 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 to achieve smooth starting of the charging management module; The power supply detection 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 of 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 for providing 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 as claimed in any one of claims 1 to 6, characterized in that: The steps of the operation method of the novel DC energy collection and management chip include: Step 1: When the initial voltage is insufficient to stimulate the internal circuit to work, the optimal oscillator in the low-voltage cold start loop generates a clock, and a clock square wave is obtained through a clock multiplier. The MOS tube MN1 is driven based on the clock square wave, and the initial input voltage is increased to 2.5V by a clamping circuit. The logic control circuit generates a POR signal to turn off the cold start, so that the circuit transitions to a normal working state; Step 2: Based on the novel MPPT algorithm, the energy collector in the energy collection circuit converts the 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, boosts the output voltage, and realizes 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 enable signals UV and EN are generated through the control logic of the control module. The enable signal UV is input into the charging management module and the secondary energy storage element to execute the Q1 management mode, and the enable signal EN is input into the system load COUT and the buck converter to execute the Q2 management mode, so as to realize efficient 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 module is used as the reference voltage signal of the new MPPT algorithm energy collection 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 switch 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 off the power tube MP to prevent the inductor current from flowing back. The two working 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 mode in step 3 specifically includes: 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 to achieve a smooth conversion from constant current to constant voltage with low static current. If the voltage of the secondary energy storage element during charging is lower than 3V, it enters the 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 the transition stage and uses a constant voltage charging method. If the charging current is reduced to 0.1C, the secondary energy storage element is in 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 mode in step 3 specifically includes: Turn on the DC-DC buck converter and design three modes of 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 the 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.

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