CN111555428B - A charging and discharging and energy management circuit for micro energy harvesting system - Google Patents

Abstract

The invention relates to a charge-discharge and energy management circuit for a micro-energy collection system, which belongs to the technical field of integrated circuits. The micro-energy harvesting system uses a micro-energy source to supply power to the load, and provides auxiliary power supply for energy storage components. The charge-discharge and energy management circuit proposed by the present invention controls the charge and discharge of the energy storage element according to the load voltage to manage the energy in the micro-energy collection system. When the energy is sufficient, the energy storage element is charged, and the excess energy is stored in the energy storage element. When the energy is insufficient, the energy storage element is discharged, and the energy storage element is used to provide additional energy to supply power to the load. The invention has the functions of charging and discharging protection and energy management of the energy storage element, and can reasonably manage the micro energy collected by the micro energy collection system; in addition, it also provides undervoltage protection and overvoltage protection, and the current discharge path of the energy storage element when undervoltage and the overpressure relief path is closed, and the overpressure relief path is opened during overpressure, which improves the stability of the system.

Description

A charging and discharging and energy management circuit for micro energy harvesting system

technical field

The invention belongs to the technical field of integrated circuits, and relates to a charging and discharging and energy management circuit used in a micro energy collection system.

Background technique

Micro-energy harvesting technology is a technology that collects weak energy that is ubiquitous in the environment to power electronic devices, such as solar energy, thermoelectric energy, and piezoelectric energy. In order to meet the power supply needs of electronic loads in different situations, it is usually necessary to use energy storage elements for assistance. When the energy is sufficient, the excess energy is stored in the energy storage elements. When the energy is insufficient, the energy storage elements are required to provide additional energy to supply power to the load. , at this time, the problem of charge and discharge management of energy storage components for micro energy harvesting systems becomes the key. Compared with the charge and discharge management circuit of traditional energy storage components, because such energy sources are usually weak and unstable, the charge and discharge and energy management circuits for micro energy not only need to consider the charge and discharge protection of energy storage components, but also Energy needs to be managed in relation to load demand and energy supply.

Contents of the invention

Aiming at the characteristics of weak and unstable energy in the micro-energy collection system, the present invention proposes a charging, discharging and energy management circuit for the micro-energy collection system, which can effectively and reasonably manage the micro-energy according to the load and energy supply requirements.

Technical scheme of the present invention is:

A charging and discharging and energy management circuit for a micro energy collection system, the micro energy collection system includes a micro energy source, a current limiting resistor, a filter capacitor and an energy storage element, the micro energy source is connected to the The output terminal of the micro-energy collection system, the load is connected between the output terminal of the micro-energy collection system and the ground, the filter capacitor is connected in parallel at both ends of the load, the voltage on the load is the load voltage, and the charge and discharge and energy The management circuit controls the charge and discharge of the energy storage element according to the load voltage to manage the energy in the micro energy harvesting system;

The charge-discharge and energy management circuit includes a first PMOS switch tube, a second PMOS switch tube and a charge-discharge and energy management module, the source of the first PMOS switch tube is grounded, and the drain is connected to the drain of the second PMOS switch tube and The load voltage; one end of the energy storage element is connected to the source of the second PMOS switch tube, and the other end is connected to one end of the load and grounded;

The charging and discharging and energy management module is used to control the opening and closing of the first PMOS switching tube and the second PMOS switching tube according to the load voltage, including a voltage dividing unit, a voltage reference source, a first comparator, a second comparator device, phase splitter, first inverter, second inverter, first buffer, second buffer and OR gate,

The voltage division unit is used to divide the load voltage to obtain a first load voltage division signal and a second load voltage division signal, wherein the voltage value of the first load voltage division signal is greater than the second load voltage division signal Signal;

The positive input terminal of the first comparator is connected to the first load voltage dividing signal, the negative input terminal is connected to the reference voltage generated by the voltage reference source, and the output terminal is connected to the input terminal of the phase splitter;

The phase splitter generates a first split output signal that is in phase with the output signal of the first comparator to the input of the first inverter, and generates a second split output signal that is inverted to the output signal of the first comparator to the second inverter The input terminal of the phase device;

The input end of the first buffer is connected to the output end of the first inverter, and its output end generates an overvoltage control signal and is connected to the gate of the first PMOS switch tube;

The positive input terminal of the second comparator is connected to the reference voltage, the negative input terminal thereof is connected to the second load dividing signal, and the output terminal thereof is connected to the first input terminal of the OR gate;

The second input terminal of the OR gate is connected to the output terminal of the second inverter, and the output terminal thereof passes through the second buffer to generate a control signal and is connected to the gate of the second PMOS switch transistor.

Specifically, the voltage dividing unit includes a first voltage dividing resistor, a second voltage dividing resistor and a third voltage dividing resistor, one end of the first voltage dividing resistor is connected to the load voltage, and the other end is connected to the second voltage dividing resistor. One end of the third voltage-dividing resistor is connected to the other end of the second voltage-dividing resistor to generate the second load voltage-dividing signal, and the other end of the third voltage-dividing resistor is connected to the ground.

Working process of the present invention is:

State ①: When the load voltage is lower than the undervoltage protection voltage, the control signal generated by the charging and discharging and energy management circuit and the overvoltage control signal both output high level, and control the second PMOS switch MP2 and the first MPOS switch MP1. disconnect, the current discharge path and overvoltage discharge path of the energy storage element are closed, and enter the undervoltage protection stage.

State ②: When the load voltage rises above the undervoltage protection voltage, the undervoltage protection state is released. If the energy collected by the micro-energy harvesting system is not enough to supply power to the load, it is now in the power supply stage of the energy storage element, charging and discharging and energy The control signal generated by the management circuit is low, the overvoltage control signal is high, the second PMOS switch tube MP2 is controlled to be in the open state, the first MPOS switch tube MP1 is turned off, and the energy storage element is discharged, and the micro energy source and the energy storage element jointly Supplying power to the load, the voltage of the energy storage element drops.

State ③: When the energy collected by the micro-energy harvesting system is sufficient to supply power, it is in the charging stage of the energy storage element at this time, the control signal generated by the charging and discharging and energy management circuit is low, and the overvoltage control signal is high, controlling the second PMOS The switch tube MP2 is turned on, the first MPOS switch tube MP1 is turned off, the micro energy source supplies power to the load and charges the energy storage element at the same time, the voltage of the energy storage element rises, and the load voltage also rises.

State ④: When the load voltage rises to exceed the set charging voltage, it indicates that the voltage charged to the energy storage element is greater than the overvoltage protection voltage. At this time, it enters the overvoltage protection stage and needs to be discharged to the ground. At this time, charge and discharge and energy management The control signal generated by the circuit is high, the overvoltage control signal is low, the second PMOS switch tube MP2 is controlled to be in the off state, the first MPOS switch tube MP1 is in the open state, and the load voltage is discharged to the ground through the first MPOS switch tube MP1, and at the same time The current charging and discharging path of the energy storage element is closed.

State ⑤: When the load voltage drops below the set charging voltage, the control signal generated by the charging and discharging and energy management circuit is low, and the overvoltage control signal is high, controlling the second PMOS switch MP2 to be in the open state, and the first The MPOS switch tube MP1 is in the off state, and so repeated, so that the voltage of the energy storage element remains unchanged and is below the overvoltage protection voltage, which plays an overvoltage protection role.

The beneficial effects of the present invention are: the present invention aims at the weak and unstable characteristics of the energy obtained by the micro-energy collection system, adopts the energy storage element as an auxiliary element, stores excess energy in the energy storage element when the energy is sufficient, and stores the excess energy in the energy storage element when the energy is insufficient The energy storage element is used to provide additional energy to supply power to the load; the invention has both the charge and discharge protection and energy management functions of the energy storage element, solves the energy management problem applicable to micro-energy collection, and can provide technology for the rational use of collected micro-energy support.

Description of drawings

Fig. 1 is a block diagram of the overall structure of a charging and discharging and energy management circuit for a micro energy harvesting system proposed by the present invention.

Fig. 2 is a circuit structure diagram of the charge-discharge and energy management module.

Fig. 3 is a simulation result diagram of a charging and discharging and energy management circuit for a micro energy harvesting system proposed by the present invention.

Detailed ways

The specific implementation manner of the present invention will be described below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, the micro energy collection system includes a micro energy source, a current limiting resistor, a filter capacitor and an energy storage element. Input, the micro energy source is an available green energy source, such as solar energy, thermoelectric energy or piezoelectric energy; the current limiting resistor plays the role of current limiting protection, and the filter capacitor is used to reduce the ripple of the load voltage; the energy storage element and The load is used to consume and store energy, and energy storage components include batteries, supercapacitors, etc.

A charge-discharge and energy management circuit for a micro-energy collection system proposed by the present invention can be fabricated into an integrated circuit using a standard CMOS process, including a first PMOS switch MP1, a second PMOS switch MP2 and a charge Discharge and energy management module, the source of the first PMOS switch MP1 is grounded, the drain is connected to the drain of the second PMOS switch MP2 and the load voltage; one end of the energy storage element is connected to the source of the second PMOS switch MP2, and the other end Connect one end of the load and ground; the charging and discharging and energy management module controls the switching state of the first PMOS switching tube MP1 and the second PMOS switching tube MP2 according to the magnitude of the load voltage, so as to realize the switching of the charging and discharging control and protection status of the energy storage element. And balance the energy supply problem under different energy input states.

As shown in Figure 2, the charging and discharging and energy management module includes a voltage dividing unit, a voltage reference source, a first comparator, a second comparator, a phase splitter, a first inverter, a second inverter, and a first buffer device, a second buffer and an OR gate, and the voltage dividing unit is used to divide the load voltage to obtain a first load dividing signal and a second load dividing signal, wherein the voltage value of the first load dividing signal is greater than that of the second load Divider signal. The positive input terminal of the first comparator is connected to the first load dividing signal, the negative input terminal is connected to the reference voltage generated by the voltage reference source, and the output terminal is connected to the input terminal of the phase splitter. The phase splitter generates two non-overlapping signals with opposite phases, which are used to ensure that the overvoltage discharge path and the energy storage element charging and discharging path will not be turned on at the same time during the overvoltage stage. The first phase-splitting output signal generated by the phase splitter, which is in phase with the output signal of the first comparator, is connected to the input terminal of the first inverter, and the second phase-splitting output signal generated by the phase splitter, which is inverse to the output signal of the first comparator, is connected to the input terminal of the first inverter. The output signal is connected to the input terminal of the second inverter. The input end of the first buffer is connected to the output end of the first inverter, and its output end generates an overvoltage control signal and is connected to the gate of the first PMOS switch MP1; the positive input end of the second comparator is connected to the reference voltage, which The negative input end is connected to the second load dividing signal, and its output end is connected to the first input end of the OR gate; the second input end of the OR gate is connected to the output end of the second inverter, and its output end passes through the second buffer A control signal is generated and connected to the gate of the second PMOS switch MP2.

Since the reference voltage generally cannot reach the set charging voltage, the load voltage is usually divided by a voltage dividing unit to obtain the first load voltage dividing signal and the second load voltage dividing signal, and then the first load voltage dividing signal and the second load voltage dividing signal are obtained. The load voltage dividing signal is compared with the reference voltage to control the state switching of the circuit. As shown in FIG. One end of a voltage dividing resistor R1 is connected to the load voltage, and the other end is connected to one end of the second voltage dividing resistor R2 to generate the first load voltage dividing signal; one end of the third voltage dividing resistor R3 is connected to the other end of the second voltage dividing resistor R2 And generate a second load divided voltage signal, the other end of which is grounded.

As shown in Figure 3, it is a schematic diagram of the simulation results of a charge-discharge and energy management circuit for a micro-energy harvesting system proposed by the present invention. The signal lines in Figure 3 are from top to bottom: preset charging voltage, load Voltage, voltage on energy storage element, control signal and overvoltage control signal.

When the load voltage is lower than the undervoltage protection voltage, the first comparator in the charging and discharging and energy management circuit outputs a low level, the second comparator outputs a high level, and both the control signal and the overvoltage control signal output a high level, controlling Both the second PMOS switch MP2 and the first MPOS switch MP1 are turned off, the current discharge path and the overvoltage discharge path of the energy storage element are closed, and the undervoltage protection stage is entered.

When the load voltage is higher than the undervoltage protection voltage and lower than the charging voltage, the output of the first comparator in the charging and discharging and energy management circuit is low, so the overvoltage control signal is high, the first MPOS switch MP1 is disconnected, and the overvoltage The release path is closed. At the same time, the output of the second comparator is low, so the control signal is low, and the second PMOS switch MP2 is controlled to be in the on state, and the current charging and discharging path of the energy storage element is opened. If the energy collected by the micro energy harvesting system is not enough to supply power to the load, the energy storage element is in the power supply stage at this time, the energy storage element discharges, the micro energy source and the energy storage element jointly supply power to the load, and the voltage of the energy storage element drops. If the energy collected by the micro-energy harvesting system is sufficient to supply power, it is now in the charging stage of the energy storage element. The micro-energy source supplies power to the load and charges the energy storage element at the same time. The voltage of the energy storage element rises, and the load voltage also rises.

When the load voltage rises to exceed the set charging voltage, it indicates that the voltage charged to the energy storage element is greater than the overvoltage protection voltage, and at this time it enters the overvoltage protection stage and needs to be discharged to the ground. The first comparator in the charge-discharge and energy management circuit outputs a high level, so the overvoltage control signal is low, the first MPOS switch MP1 is turned on, and the overvoltage discharge path is opened. At the same time, the second inverter outputs a high level, so that the control signal outputs a high level, and the current charging and discharging path of the energy storage element is closed, thereby achieving the overvoltage protection function. When the load voltage drops below the set charging voltage, the control signal generated by the charging and discharging and energy management circuit is low, and the overvoltage control signal is high, controlling the second PMOS switch MP2 to be in the on state, and the first MPOS switch tube MP1 is in the off state, and this is repeated so that the voltage of the energy storage element remains unchanged and is below the overvoltage protection voltage, which plays the role of overvoltage protection.

Those skilled in the art can make various other specific modifications and combinations based on the technical revelations disclosed in the present invention without departing from the essence of the present invention, and these modifications and combinations are still within the protection scope of the present invention.

Claims (2)

1. A charging and discharging and energy management circuit for a micro energy harvesting system, the micro energy harvesting system includes a micro energy source, a current limiting resistor, a filter capacitor and an energy storage element, after the micro energy source passes through a current limiting resistor Connect the output terminal of the micro-energy collection system, the load is connected between the output terminal of the micro-energy collection system and the ground, the filter capacitor is connected in parallel at both ends of the load, the voltage on the load is the load voltage, and the charging and discharging And the energy management circuit controls the charge and discharge of the energy storage element according to the load voltage to manage the energy in the micro energy harvesting system; It is characterized in that the charge-discharge and energy management circuit includes a first PMOS switch tube, a second PMOS switch tube and a charge-discharge and energy management module, the source of the first PMOS switch tube is grounded, and the drain is connected to the second PMOS switch tube The drain and the load voltage; one end of the energy storage element is connected to the source of the second PMOS switch tube, and the other end is connected to one end of the load and grounded; The charging and discharging and energy management module is used to control the opening and closing of the first PMOS switching tube and the second PMOS switching tube according to the load voltage, including a voltage dividing unit, a voltage reference source, a first comparator, a second comparator device, phase splitter, first inverter, second inverter, first buffer, second buffer and OR gate, The voltage division unit is used to divide the load voltage to obtain a first load voltage division signal and a second load voltage division signal, wherein the voltage value of the first load voltage division signal is greater than the second load voltage division signal Signal; The positive input terminal of the first comparator is connected to the first load voltage dividing signal, the negative input terminal is connected to the reference voltage generated by the voltage reference source, and the output terminal is connected to the input terminal of the phase splitter; The phase splitter generates a first split output signal that is in phase with the output signal of the first comparator to the input of the first inverter, and generates a second split output signal that is inverted to the output signal of the first comparator to the second inverter The input terminal of the phase device; The input end of the first buffer is connected to the output end of the first inverter, and its output end generates an overvoltage control signal and is connected to the gate of the first PMOS switch tube; The positive input terminal of the second comparator is connected to the reference voltage, the negative input terminal thereof is connected to the second load dividing signal, and the output terminal thereof is connected to the first input terminal of the OR gate; The second input terminal of the OR gate is connected to the output terminal of the second inverter, and the output terminal thereof passes through the second buffer to generate a control signal and is connected to the gate of the second PMOS switch transistor. 2. The charge-discharge and energy management circuit for a micro-energy harvesting system according to claim 1, wherein the voltage dividing unit comprises a first voltage dividing resistor, a second voltage dividing resistor and a third voltage dividing resistor , one end of the first voltage dividing resistor is connected to the load voltage, and the other end is connected to one end of the second voltage dividing resistor to generate the first load voltage dividing signal; one end of the third voltage dividing resistor is connected to the second voltage dividing resistor The other end generates the second load divided voltage signal, and the other end is grounded.

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