Power management circuit and power supply system

Abstract

The invention relates to the technical field of energy, in particular to a power management circuit and a power supply system, which are used for reducing circuit loss and improving output performance and output efficiency of an energy device at low output voltage. The power management circuit comprises a rectifying circuit, a primary step-down circuit and at least one secondary step-down circuit which are connected in sequence, the input end of the rectifying circuit is connected with the energy device, the rectifying circuit is used for converting alternating current output by the energy device into direct current with a first voltage value, and the first voltage value is determined in advance according to a charge-voltage output characteristic curve of the energy device; the primary step-down circuit is used for reducing the direct current of the first voltage value into a second voltage value, and the second voltage value is determined according to the output power of the energy device under each voltage value; and the at least one secondary step-down circuit is used for reducing the direct current of the second voltage value to a target output voltage.

Description

Technical Field

[0001] This application relates to the field of energy technologies, and particularly to a power management circuit and a power supply system. Background Art

[0002] With the rapid development of the Internet of Things and distributed sensor technologies, miniaturized and self-powered energy solutions have become a core requirement for driving technological innovation.

[0003] The triboelectric nanogenerator (TENG) has been widely used due to its advantages such as simple preparation, wide material selection, and high mechanical energy conversion efficiency. The TENG can convert low-frequency mechanical energy in the environment (such as human motion, wind energy, wave energy) into electrical energy to provide sustainable energy supply for sensing devices. However, the output characteristics of the TENG show a high open-circuit voltage (up to several thousand volts) and a low short-circuit current (microamp-level alternating current), which do not match the low-voltage requirements (usually below 10V) and direct current (milliamp-level) of most electronic devices, sensors, and electrochemical systems.

[0004] Therefore, an efficient power management circuit (PMC) has become a key technology for unlocking the application potential of TENGs. Summary of the Invention

[0005] This application discloses a power management circuit and a power supply system to reduce circuit losses and improve the output performance and output efficiency of energy devices at low output voltages.

[0006] To achieve the above object, this application provides the following technical solutions: In a first aspect, this application provides a power management circuit, which includes: a rectification circuit, a primary buck circuit, and at least one secondary buck circuit connected in sequence; The rectification circuit, with its input terminal connected to the energy device, is used to convert the alternating current output by the energy device into direct current with a first voltage value, and the first voltage value is determined in advance according to the charge-voltage output characteristic curve of the energy device; The primary buck circuit is used to step down the direct current with the first voltage value to a second voltage value, and the second voltage value is determined according to the output power of the energy device at each voltage value; The at least one secondary buck circuit is used to step down the direct current with the second voltage value to a target output voltage.

[0007] In the embodiment of the present application, the output voltage of the energy device is step-down graded through a primary step-down circuit and at least one secondary step-down circuit. On the one hand, the output voltage of the primary step-down circuit is higher than the target output voltage, avoiding the problem that the circuit loss on the internal impedance of the step-down circuit increases rapidly due to too low output voltage. On the other hand, the output voltage of the primary step-down circuit is much smaller than the output voltage of the energy device, and the energy loss of the secondary step-down circuit is less. Therefore, the step-down grading method can reduce the circuit loss of the entire step-down process, improve the output efficiency at low output voltage. At the same time, the first voltage value is determined according to the charge-voltage output characteristic curve of the energy device, so that the output characteristic of the energy device can reach the best matching state with the power management circuit, and the output performance of the power management circuit at low output voltage is improved.

[0008] Further, the first voltage value is determined according to the relationship curve between the output voltage and output energy of the energy device, and the relationship curve between the output voltage and output energy is determined according to the charge-voltage output characteristic curve of the energy device.

[0009] Further, the second voltage value is the voltage value corresponding to the maximum output power among the output powers of the energy device at each voltage value.

[0010] Further, the primary step-down circuit includes: a gas discharge tube, a diode, an inductor, and a capacitor; The gas discharge tube is connected in series with the inductor between the positive output terminal of the rectifier circuit and the positive input terminal of the at least one secondary step-down circuit. The middle node of the gas discharge tube and the inductor is connected to the cathode of the diode. The anode of the diode is connected to the ground wire. The first end of the capacitor is connected to the positive input terminal of the at least one secondary step-down circuit, and the second end of the capacitor is connected to the ground wire.

[0011] Further, there are multiple secondary step-down circuits, and the multiple secondary step-down circuits are connected in series.

[0012] Further, the secondary step-down circuit includes a step-down chip.

[0013] Further, the power management circuit further includes: an energy storage circuit, connected between the rectifier circuit and the primary step-down circuit, for storing the electric energy output by the rectifier circuit.

[0014] Further, the output voltage of the energy device is greater than a preset threshold.

[0015] Further, the energy device at least includes: a triboelectric nanogenerator.

[0016] In a second aspect, an embodiment of the present application provides a power supply system, including: an energy device and the power management circuit described in the first aspect; The power management circuit is connected to the energy device and the electrical appliance device, and is configured to step down the output voltage of the energy device and supply the stepped-down electric energy to the electrical appliance device. Description of the Drawings

[0017] Figure 1 It is a schematic architecture diagram of a power management circuit provided by an embodiment of the present application; Figure 2 It is a relationship curve diagram of the output charge and output voltage of an energy device provided by an embodiment of the present application; Figure 3 It is a relationship curve diagram of the output voltage and output energy of an energy device provided by an embodiment of the present application; Figure 4 It is a circuit topology schematic diagram of a primary step-down circuit provided by an embodiment of the present application; Figure 5 It is an output power curve diagram of an energy device provided by an embodiment of the present application; Figure 6 It is a schematic diagram of the principle of circuit loss provided by an embodiment of the present application; Figure 7 It is a schematic architecture diagram of another power management circuit provided by an embodiment of the present application; Figure 8 It is a schematic diagram of the circuit efficiency comparison with or without a secondary step-down circuit provided by an embodiment of the present application; Figure 9 It is a schematic diagram of the circuit efficiency comparison with or without another secondary step-down circuit provided by an embodiment of the present application; Figure 10 It is a schematic diagram of the circuit efficiency comparison with or without yet another secondary step-down circuit provided by an embodiment of the present application. Detailed Embodiments

[0018] In order to make the objectives, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0019] The application scenarios described in the embodiments of the present application are for more clearly illustrating the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided by the embodiments of the present application. Those of ordinary skill in the art can know that with the emergence of new application scenarios, the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems. Among them, in the description of the present application, unless otherwise specified, the meaning of "a plurality" is two or more.

[0020] Before introducing the power management circuit and power supply system provided by the embodiments of the present application, for the convenience of understanding, the technical background of the embodiments of the present application will be introduced in detail first.

[0021] With the rapid development of the Internet of Things and distributed sensor technologies, miniaturized and self-powered energy solutions have become the core demand for promoting technological innovation.

[0022] Due to its advantages such as simple preparation, wide material selection, and high mechanical energy conversion efficiency, TENG has been widely used. TENG can convert low-frequency mechanical energy in the environment (such as human movement, wind energy, wave energy) into electrical energy to provide sustainable energy supply for sensing devices. However, the output characteristics of TENG show high open-circuit voltage (up to thousands of volts) and low short-circuit current (microamp-level alternating current), which do not match the low-voltage requirements (usually below 10 volts V) and direct current (milliamp level) of most electronic devices, sensors, and electrochemical systems. Therefore, an efficient PMC has become the key technology to unlock the application potential of TENG.

[0023] Most of the PMC architectures in the related technologies (such as inductance-capacitance oscillation circuits, transformer-coupled circuits, switched-capacitor converters) are committed to obtaining the maximum energy conversion efficiency by optimizing energy storage components and reducing switching losses. However, these solutions lack a detailed study of the output characteristics of TENG, and the actual efficiency in the low-voltage range (<10V) is significantly lower than the claimed optimal value. Therefore, the PMC architectures proposed in the related technologies still cannot meet the working requirements of most sensors, electrochemical systems, and energy storage systems.

[0024] In view of this, in the embodiments of the present application, a power management circuit and a power supply system are provided. Through a primary buck circuit and at least one secondary buck circuit, the output voltage of the energy device is step-down voltage graded. On the one hand, the output voltage of the primary buck circuit is higher than the target output voltage, avoiding the problem that the circuit loss on the internal impedance of the buck circuit increases rapidly due to too low output voltage. On the other hand, the output voltage of the primary buck circuit is much smaller than the output voltage of the energy device, and the energy loss of the secondary buck circuit is less. Therefore, the step-down voltage graded method can reduce the circuit loss in the whole buck process and improve the output efficiency at low output voltage. At the same time, the first voltage value is determined according to the charge-voltage output characteristic curve of the energy device, so that the output characteristic of the energy device can reach the best matching state with the power management circuit, and the output performance of the power management circuit at low output voltage is improved.

[0025] It should be noted that the embodiments of the present application are applicable to fields such as self-powered sensors, electrochemical systems, lithium-ion battery charging, and distributed energy management. The energy device mentioned in the embodiments of the present application refers to an energy device with a high output voltage characteristic, that is, the output voltage of the energy device is greater than a preset threshold (which can be set according to experience specifically), and it can include but is not limited to triboelectric nanogenerators. In the following embodiments of the present application, the triboelectric nanogenerator is taken as an example for illustration, and the structure and preparation materials of the triboelectric nanogenerator are not limited.

[0026] After introducing the background technology of the embodiments of the present application, the overall inventive concept of the embodiments of the present application will be described below.

[0027] Taking the TENG as an example of the energy device, the inventors of the present application found that the PMC architecture proposed in the related technology cannot meet the working requirements of most sensors, electrochemical systems, and energy storage systems. On the one hand, the reason is the lack of precise regulation of the key nodes of the circuit, resulting in the output characteristic of the TENG not being able to reach the best matching state with the PMC, and the output energy of the TENG being severely limited. On the other hand, affected by the internal resistance of the circuit and the voltage drop of the diode, huge energy losses occur at low output voltages, resulting in a reduction in the efficiency of the circuit, which severely limits the practical application of the TENG.

[0028] The embodiments of the present application propose a segmented buck PMC architecture to solve the problems of low output performance and low efficiency in the low voltage range caused by the application of the traditional buck circuit to the TENG. Specifically, on the one hand, the embodiments of the present application adopt a step-down voltage graded strategy to solve the problem of reduced efficiency of the PMC in the low voltage range. On the other hand, the charge-voltage output characteristic curve of the TENG is used as the direct data reference benchmark of the power management circuit to solve the problem that the output characteristic of the TENG cannot reach the best matching state with the PMC.

[0029] After introducing the background art and the overall inventive concept of the embodiments of the present application, the power management circuit and the power supply system provided by the embodiments of the present application will be described in detail below with reference to specific embodiments.

[0030] Referring to Figure 1 As shown, it is a schematic structural diagram of a power management circuit in an embodiment of the present application, including: a rectification circuit 10, a primary step-down circuit 11, and at least one secondary step-down circuit 12 connected in sequence.

[0031] The rectification circuit 10, with its input terminal connected to the energy device, is used to convert the alternating current output by the energy device into direct current with a first voltage value, where the first voltage value is determined in advance according to the charge-voltage output characteristic curve of the energy device.

[0032] The primary step-down circuit 11 is used to step down the direct current with the first voltage value to a second voltage value, and the second voltage value is determined according to the output power of the energy device at each voltage value.

[0033] At least one secondary step-down circuit 12 is used to step down the direct current with the second voltage value to the target output voltage.

[0034] In practical applications, the rectification circuit is used to rectify the alternating current output by the energy device into direct current. After the rectification circuit, an energy storage circuit, such as an energy storage capacitor, can also be connected to store the electric energy output by the rectification circuit and serve as the excitation source of the primary step-down circuit.

[0035] Specifically, the charge-voltage output characteristic curve of the energy device can be obtained by pre-measurement. The charge-voltage output characteristic curves of different energy devices are different, and the corresponding first voltage values are also different.

[0036] When specifically determining the first voltage value according to the charge-voltage output characteristic curve of the energy device, first, according to the charge-voltage output characteristic curve of the energy device, the relationship curve between the output voltage and the output energy of the energy device can be determined, and then, according to the relationship curve between the output voltage and the output energy of the energy device, the first voltage value can be determined. For example, the voltage value corresponding to the maximum output energy in the relationship curve between the output voltage and the output energy is determined as the first voltage value.

[0037] In one example, the energy device is a TENG for example, as Figure 2 shown, Figure 2 shows the charge-voltage output characteristic curve of the TENG. This curve can accurately describe the output charge of the TENG at different output voltages. The product of the abscissa and ordinate of each point on the curve represents the output energy of the TENG at this output voltage.

[0038] Based on this, the relationship curve between the output voltage and the output energy of the TENG can be determined, such asFigure 3 As shown, from Figure 3 it can be seen that the output energy reaches the maximum when the output voltage is about 1500 V. Therefore, the first voltage value can be selected as 1500 V.

[0039] In practical applications, the main function of the primary step-down circuit is to step down the direct current of the first voltage value to the second voltage value and generate a relatively stable high output current.

[0040] In some possible implementation manners, as Figure 4 shown, the primary step-down circuit includes: a gas discharge tube 41, a diode 42, an inductor 43, and a capacitor 44.

[0041] The gas discharge tube 41 is connected in series with the inductor 43 between the positive output terminal of the rectifier circuit and the positive input terminal of at least one secondary step-down circuit. The middle node of the gas discharge tube 41 and the inductor is connected to the cathode of the diode 42. The anode of the diode 42 is connected to the ground wire. The first end of the capacitor 44 is connected to the positive input terminal of at least one secondary step-down circuit, and the second end of the capacitor 44 is connected to the ground wire.

[0042] It should be noted that the structure of the primary step-down circuit shown above is only an example. In other embodiments of the present application, the primary step-down circuit can also adopt other topological structures, but it is necessary to ensure that the threshold voltages of various components in the primary step-down circuit match the first voltage value. Figure 4 When specifically implemented, the second voltage value is determined according to the output power of the energy device at each voltage value. The output power of the energy device at each voltage value can be obtained by measurement after connecting the primary step-down circuit. Specifically, the second voltage value can be the voltage value corresponding to the maximum output power among the output powers of the energy device at each voltage value.

[0043] In one example, taking the TENG as the energy device and the primary step-down circuit as

[0044] shown as an example, as Figure 4 shown, Figure 5 shown, Figure 5 shows the output power of the TENG at each voltage value. From Figure 5 it can be seen that when the input power is 14.3 milliwatts (mW), the output power at an output voltage of 16 V is 12.9 mW, and the conversion efficiency of the circuit reaches 90.9% at this time.

[0045] Figure 6 Analyzed the energy dissipation situation inside the primary step-down circuit. From Figure 6It can also be seen that in the low output voltage range, the conversion efficiency of the circuit is relatively low, which is not conducive to the practical application of the TENG. This is because too low output voltage will cause the energy loss on the diode and internal impedance to increase rapidly, which is also the fundamental reason for the low efficiency of the PMC architecture in the related technology at low output voltage.

[0046] In practical applications, the secondary buck circuit is used to further step down the direct current of the second voltage value to the target output voltage. Herein, the target output voltage refers to the voltage required by the electrical device, and the target output voltage can be 5V, 3.6V, 1.8V, etc., and the embodiments of the present application do not make any limitations thereto.

[0047] When specifically implemented, in the case of multiple secondary buck circuits, the multiple secondary buck circuits can be connected in series to step down voltage step by step, and the embodiments of the present application do not make any limitations to the number of secondary buck circuits. The secondary buck circuit can be implemented by using a buck chip or a buck circuit, and the embodiments of the present application do not make any limitations thereto.

[0048] The above has separately described each part of the power management circuit provided by the embodiments of the present application. Next, in combination with Figure 7 , taking the energy device as the TENG as an example and the primary buck circuit as Figure 4 shown as an example, and taking the case of including one secondary buck circuit as an example, the overall architecture of the power management circuit provided by the embodiments of the present application will be described.

[0049] As Figure 7 shown, the power management circuit provided by the embodiments of the present application is connected between the energy device and the electrical device, and its overall architecture includes: a rectification and energy storage circuit 71, a primary buck circuit 72, and a secondary buck circuit 73.

[0050] The rectification and energy storage circuit 71 is used to rectify the alternating current output by the TENG into direct current and store the energy in the energy storage capacitor as the excitation source of the primary buck circuit 72.

[0051] The primary buck circuit 72 includes a gas discharge tube, a freewheeling diode, an inductor, and an output capacitor, and its main function is to reduce the input voltage with the first voltage value to the second voltage value and generate a relatively stable high output current.

[0052] The secondary buck circuit 73 is used to further adjust the input voltage with the second voltage value to the target output voltage and supply it to the electrical device.

[0053] Based on Figure 7 the power management circuit architecture shown, taking the first voltage value as 1500 V and the target output voltage as 5V as an example. The traditional buck circuit directly steps down the input voltage from 1500 V to 5 V, which will cause a large amount of energy loss.

[0054] In the power management circuit provided by the embodiment of the present application, the voltage reduction path of the hierarchical voltage reduction circuit is to first reduce the voltage from 1500V to 16V, and then from 16V to 5V. The primary voltage reduction circuit first reduces the 1500V input to 16V to ensure its high efficiency, and the secondary voltage reduction circuit reduces the 16V input voltage to 5V to match the backend application.

[0055] In a specific experiment, before and after the introduction of the secondary voltage reduction circuit, for the output performance of the triboelectric nanogenerator, at output voltages of 5V, 3.6V, and 1.8V, the output currents are increased from 2.05 mA, 2.52 mA, and 3.31 mA to 2.41 mA, 3.34 mA, and 5.84 mA respectively, and the output powers are increased from 10.53 mW, 9.25 mW, and 6.05 mW to 12.12 mW, 12.27 mW, and 10.75 mW respectively. The overall efficiency of the circuit is also increased from 73.5%, 64.6%, and 42.2% to 84.6%, 85.6%, and 75% respectively.

[0056] Specifically, according to different output voltages, it can be divided into the following three cases: Case 1, as Figure 8 shown, when the input voltage is 1500V, the input power is 14.03 mW, and the output voltage is set to 5V. The voltage reduction path of the traditional voltage reduction circuit is from 1500V to 5V, the final output current is 2.05 mA, the output power is 10.53 mW, and the circuit efficiency is 73.5%.

[0057] In the power management circuit provided by the embodiment of the present application, the voltage reduction path of the hierarchical voltage reduction circuit is from 1500V to 16V and then to 5V, the final output current is increased to 2.41 mA, the output power is increased to 12.12 mW, and the circuit efficiency is increased to 84.6%.

[0058] Case 2, as Figure 9 shown, when the input voltage is 1500V, the input power is 14.03 mW, and the output voltage is set to 3.6V. The voltage reduction path of the traditional voltage reduction circuit is from 1500V to 3.6V, the final output current is 2.52 mA, the output power is 9.25 mW, and the circuit efficiency is 64.6%.

[0059] In the power management circuit provided by the embodiment of the present application, the voltage reduction path of the hierarchical voltage reduction circuit is from 1500V to 16V and then to 3.6V, the final output current is increased to 3.34 mA, the output power is increased to 12.27 mW, and the circuit efficiency is increased to 85.6%.

[0060] Case 3, as Figure 10As shown, when the input voltage is 1500 V, the input power is 14.03 mW, and the output voltage is set to 1.8 V. The voltage reduction path of the traditional buck circuit is from 1500 V to 1.8 V, and the final output current is 3.31 mA, the output power is 6.05 mW, and the circuit efficiency is 42.2%.

[0061] For the power management circuit provided by the embodiment of the present application, the voltage reduction path of the hierarchical buck circuit is from 1500 V to 16 V and then to 1.8 V. The final output current is increased to 5.84 mA, the output power is increased to 10.75 mW, and the circuit efficiency is increased to 75%.

[0062] From the above experimental data, it can be seen that in the embodiment of the present application, through the primary buck circuit and at least one secondary buck circuit, the output voltage of the energy device is hierarchically bucked. On the one hand, the output voltage of the primary buck circuit is higher than the target output voltage, avoiding the problem that the circuit loss on the internal impedance of the buck circuit increases rapidly due to too low output voltage. On the other hand, the output voltage of the primary buck circuit is much smaller than the output voltage of the energy device, and the energy loss of the secondary buck circuit is less. Therefore, the hierarchical bucking method can reduce the circuit loss in the entire bucking process, improve the output efficiency at low output voltages. At the same time, according to the charge-voltage output characteristic curve of the energy device, the first voltage value is determined, so that the output characteristics of the energy device can reach the best matching state with the power management circuit, and the output performance of the power management circuit at low output voltages is improved.

[0063] Based on the same inventive concept, the embodiment of the present application also provides a power supply system, including: an energy device and the power management circuit provided by the embodiment of the present application, wherein the power management circuit is connected to the energy device and the electrical appliance device, and is used to step down the output voltage of the energy device and supply the stepped-down electric energy to the electrical appliance device.

[0064] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present application, and all should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A power management circuit applied to an energy device, characterized in that: The power management circuit comprises: a rectifier circuit, a primary buck circuit, and at least one secondary buck circuit connected in sequence; The rectifier circuit has an input end connected to the energy device, and is used to convert the alternating current output by the energy device into direct current of a first voltage value, where the first voltage value is determined in advance according to a charge-voltage output characteristic curve of the energy device; The primary step-down circuit is used to step down the DC power of the first voltage value into a second voltage value, where the second voltage value is determined according to the output power of the energy device at various voltage values; The at least one secondary step-down circuit is used to step down the direct current of the second voltage value to a target output voltage.

2. The circuit according to claim 1, characterized in that The first voltage value is determined based on a relationship curve between the output voltage and output energy of the energy device, and the relationship curve between the output voltage and output energy is determined based on a charge-voltage output characteristic curve of the energy device.

3. The circuit according to claim 1, characterized in that The second voltage value is a voltage value corresponding to the maximum output power among the output powers of the energy device at various voltage values.

4. The circuit according to claim 1, characterized in that The primary step-down circuit comprises: a gas discharge tube, a diode, an inductor and a capacitor; The gas discharge tube and the inductor are connected in series between the positive output terminal of the rectifier circuit and the positive input terminal of the at least one secondary buck circuit, the intermediate node between the gas discharge tube and the inductor is connected to the cathode of the diode, the anode of the diode is connected to the ground wire, the first end of the capacitor is connected to the positive input terminal of the at least one secondary buck circuit, and the second end of the capacitor is connected to the ground wire.

5. The circuit according to claim 1, characterized in that There are multiple secondary buck circuits, and the multiple secondary buck circuits are connected in series.

6. The circuit according to claim 1, characterized in that The secondary buck circuit includes a buck chip.

7. The circuit according to any one of claims 1 to 6, characterized in that: The power management circuit further includes: an energy storage circuit connected between the rectifier circuit and the primary step-down circuit, and used for storing the electric energy output by the rectifier circuit.

8. The circuit according to any one of claims 1 to 6, characterized in that: The output voltage of the energy device is greater than a preset threshold.

9. The circuit according to any one of claims 1 to 6, characterized in that: The energy device at least includes: a friction nanogenerator.

10. A power supply system, characterized in that: include: An energy device and a power management circuit as claimed in any one of claims 1 to 9; The power management circuit is connected to the energy device and the power-consuming device, and is used to reduce the output voltage of the energy device and provide the reduced voltage electric energy to the power-consuming device.

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