Automatic charging and power supply system based on radio frequency capture

Abstract

The invention provides an automatic charging and power supply system based on radio frequency capture. The automatic charging and power supply system comprises an LC tuning circuit and a rectification collection circuit connected with the LC tuning circuit. The LC tuning circuit comprises an antenna SMA interface, a first gear shifting sheet of the antenna SMA interface, a second gear switching circuit connected with the first gear switching circuit, and a voltage-multiplying detection circuit and a field effect transistor circuit which are respectively connected with the first gear shifting sheet; the voltage-multiplying detection circuit comprises a first capacitor, a second capacitor, a first diode and a second diode, one end of the first capacitor is connected with the anode of the second diode, the cathode of the second diode is connected with the second capacitor, and the anode of the first diode is connected with the first capacitor and the second capacitor; the cathode of the second diode is connected with the first capacitor and the second diode. Through a radio frequency energy self-capture technology and an intelligent control system, automatic charging and continuous power supply of sensor equipment are realized, dependence on a battery with limited service life is reduced, and energy utilization efficiency and equipment reliability are improved.

Description

Technical Field

[0002] The present invention relates to the field of automatic charging, and particularly to an automatic charging power supply system based on radio frequency capture. Background Art

[0004] After researching the radio waves in the environment, it is found that radio waves may be used as a potential energy source. Although the energy density of electromagnetic waves in nature is low, radio frequency signals such as broadcasts, mobile phone signals, and wireless local area networks are widely distributed in the surrounding environment, and the power density is continuously increasing.

[0005] Moreover, as a core component of the Internet of Things, sensor devices have faced problems such as short lifespan, high energy consumption, and high maintenance costs under the limitation of relying on batteries with limited lifespan in the past. The aim is to solve the problem of energy supply for sensor devices by using radio waves in the environment, and improve energy utilization efficiency and sustainability. Summary of the Invention

[0007] In view of this, the main object of the present invention is to reduce the dependence on batteries with limited lifespan, and improve energy utilization efficiency and device reliability.

[0008] The present invention provides an automatic charging power supply system based on radio frequency capture, including an LC tuning circuit and a rectifying and collecting circuit connected to the LC tuning circuit; The LC tuning circuit includes an antenna SMA interface and a first gear switch of the antenna SMA interface, a second gear switch circuit connected to the first gear switching circuit, and a voltage doubling detection circuit and a field effect transistor circuit respectively connected to the first gear switch; The voltage doubling detection circuit includes a first capacitor, a second capacitor, a first diode, and a second diode. One end of the first capacitor is connected to the anode of the second diode, the cathode of the second diode is connected to the second capacitor, the anode of the first diode is connected to the first capacitor and the second capacitor, and the cathode of the second diode is connected to the first capacitor and the second diode; Wherein, when the input signal is in the negative half-wave, the first diode conducts, and charges are accumulated in the first capacitor; when the input signal becomes the positive half-wave, the charges accumulated in the first capacitor are loaded into the signal, so that the output voltage is doubled, and the second capacitor undertakes the filtering function.

[0009] In some embodiments of the present invention, the first gear switching circuit is a circuit for switching between the voltage-doubling detection circuit and the field-effect transistor circuit; in a medium-wave environment, the first gear switching circuit is switched to the voltage-doubling circuit gear so that the first capacitor is fully charged. When the input signal is in the negative half-wave, the first diode conducts, and charges are accumulated in the first capacitor; when the input signal becomes the positive half-wave, the charges accumulated in the first capacitor are loaded onto the input signal, doubling the output voltage; if the first capacitor is not fully charged, the output voltage is much lower than twice the input voltage.

[0010] In some embodiments of the present invention, the second gear switching circuit is a switching circuit for changing the inductance value currently connected to the LC tuning circuit; The second gear switching circuit includes a medium-wave circuit gear and a short-wave circuit gear. The medium-wave circuit gear is used to collect electromagnetic waves of 300 - 30 MHz, and the short-wave circuit gear is used to collect electromagnetic waves of 3 - 30 MHz.

[0011] An automatic charging and power supply system based on radio frequency capture provided by the present invention has the following beneficial effects: Through radio frequency energy self-capture technology and an intelligent control system, automatic charging and continuous power supply of sensor devices are realized, reducing the dependence on limited-life batteries and improving energy utilization efficiency and device reliability. Description of the Drawings

[0013] Figure 1 It is the circuit diagram of the LC tuning circuit in the automatic charging and power supply system based on radio frequency capture according to an embodiment of the present invention; Figure 2 It is the schematic diagram of the radio frequency collection circuit according to an embodiment of the present invention; Figure 3 It is the voltage-doubling detection circuit according to an embodiment of the present invention; Figure 4 It is the schematic diagram of the filtered waveform according to an embodiment of the present invention; Detailed Embodiments

[0014] The following further details the present application with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only for explaining the related invention and not for limiting the invention. Additionally, it should be noted that for the sake of description, only parts related to the relevant invention are shown in the drawings. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The following will detail the present application with reference to the drawings and embodiments.

[0015] In the present application, an automatic charging and power supply system based on radio frequency capture includes an LC tuning circuit and a rectifying and collecting circuit connected to the LC tuning circuit; The LC tuning circuit includes an antenna SMA interface and a first gear selector for the antenna SMA interface, a second gear switching circuit connected to the first gear switching circuit, and a voltage doubling detection circuit and a field effect transistor circuit respectively connected to the first gear selector; The voltage doubling detection circuit includes a first capacitor, a second capacitor, a first diode and a second diode. One end of the first capacitor is connected to the anode of the second diode, the cathode of the second diode is connected to the second capacitor, the anode of the first diode is connected to the first capacitor and the second capacitor, and the cathode of the second diode is connected to the first capacitor and the second diode; Wherein, when the input signal is in the negative half-wave, the first diode conducts, and charges are accumulated in the first capacitor; when the input signal becomes the positive half-wave, the charges accumulated in the first capacitor are loaded into the signal, doubling the output voltage, and the second capacitor undertakes the filtering function.

[0016] Please refer to Figure 1 , which shows the circuit diagram of the LC tuning circuit in the automatic charging and power supply system based on radio frequency capture of the present application.

[0017] As Figure 1 shown, analysis of the LC tuning, filtering and rectifying circuit: Medium wave and short wave tuning switching: The medium wave and short wave switching is divided into five gears, namely medium wave 1, medium wave 2, short wave 1, short wave 2, and short wave 3. The medium wave circuit gear is responsible for collecting electromagnetic waves of 300K~30MHz, and the short wave gear is responsible for collecting electromagnetic waves of 3~30MHz. After switching gears, the inductance value L in the currently connected LC tuning circuit will change.

[0018] Voltage doubling circuit and field effect transistor switching: In a medium wave environment or an environment with strong overall electromagnetic waves, the voltage doubling circuit gear can be used, so that the capacitor C4 in the figure can be fully charged. When the signal is in the negative half-wave, the diode conducts, and charges are accumulated in C4; when the signal becomes the positive half-wave, the charges accumulated in C4 are loaded into the signal, doubling the output voltage. If C4 is not fully charged, the output voltage will be much lower than twice the input voltage.

[0019] In a short-wave environment or an environment with weak signals, the field-effect transistor gear can be used. For an N-channel field-effect transistor, when there is no voltage on the gate, no current will flow between the source and the drain. At this time, the field-effect transistor is in the cut-off state. When a positive voltage is applied to the gate of the N-channel MOS field-effect transistor, due to the effect of the electric field, the negative electrons in the source and drain of the N-type semiconductor are attracted and rush towards the gate. However, due to the blocking of the oxide film, electrons accumulate in the P-type semiconductor between the two N-channels, thus forming a current, making the source and drain conduct, and thus realizing the high-frequency rectification part after the LC tuning circuit.

[0020] It should be noted that for the micro-current collection part of BQ25570: If the device operates normally, the VBAT_OK pin of the BQ25570 chip will continuously output a high-level signal. If this pin is directly connected to an LED, it will consume too much electrical energy stored in the lithium-ion battery / ultracapacitor, which will slightly affect the efficiency and battery life of the device. Therefore, we use a momentary switch to prevent the indicator light from consuming excessive power, and it is also convenient to quickly observe the working state of the device by pressing the momentary switch during device maintenance.

[0021] In a situation where the electromagnetic environment is relatively complex, multiple devices can also be connected in parallel using CN2 to simultaneously cover multi-band electromagnetic waves and perform the power collection circuit.

[0022] In a specific embodiment, an energy conversion and storage system is provided. Through the radio-frequency energy self-capture technology, we can convert the captured micro-electrical energy into a stable DC power supply for use by sensor devices. At the same time, we adopt advanced energy storage technologies such as supercapacitors or lithium batteries to store and release electrical energy to ensure that the sensor devices can still operate normally when the radio wave energy is unstable or temporarily missing.

[0023] As Figure 2 shown, the high-frequency signal sensed by the antenna is input into the tuning circuit to select a specific electromagnetic wave collection frequency. The tuning circuit is essentially an LC resonance circuit, and the frequency at which the electromagnetic wave collection power reaches the maximum is the resonance frequency of the LC resonance circuit.

[0024] As Figure 3 shown, the working principle of the voltage doubler detection circuit is: when the signal is in the negative half-wave, D1 conducts and charges are accumulated in C1; when the signal becomes the positive half-wave, the charges accumulated in C1 are loaded onto the signal, doubling the output voltage, and C2 undertakes the filtering function.

[0025] Figure 4 , is the waveform received on the voltage doubler detection circuit from the FM frequency-modulated radio wave emitted by the standard signal generator. The solid line part is the transmitted waveform, and the dashed line is the filtered waveform after voltage doubling.

[0026] Due to the extremely low power of electromagnetic waves in the actual environment, in order to further improve the power generation power and efficiency, we adopted the TI BQ25570 chip and designed the peripheral circuit for low-power energy harvesting.

[0027] TI BQ25570 is a series of energy harvesting and storage chips launched by Texas Instruments. BQ25570 is an energy management solution chip with ultra-low power consumption, which can harvest energy from weak energy sources and convert it into a stable power supply for application use.

[0028] The energy harvesting source must provide a minimum level of power to the integrated circuit. The minimum input power required for the integrated circuit to exit cold start can be estimated as: , where I-STR_ELM_LEAK@1.8V is the storage element leakage current at 1.8 V, RSTOR(CS) is the equivalent resistive load on VSTOR during cold start, and 0.05 is an estimate of the worst-case efficiency of the cold start circuit.

[0029] Once the integrated circuit loses cold start and the system load is activated (e.g., using the VBAT_OK signal), the energy harvesting element must provide at least enough power to the main boost charger to meet the average system load. Assuming RSTOR(AVG) represents the average resistive load on VSTOR, the following simplified formula gives an estimate of the minimum input power required during system operation: , where ηEST can be derived from the given input voltage, current, and VBAT_OV data sheet efficiency curve. The above simplified equation assumes that when the chip is still providing power, the system enters a low-power or sleep mode long enough to charge the storage element.

[0030] Through the circuit peripheral design for the BQ25570 chip, we enabled the chip to be activated when the front-end input voltage exceeds 330 mV, enter the operating state, and boost and rectify to 4.0V ± 0.05V. The startup current is from 0.1uA to 1mA.

[0031] The above are only some embodiments of the present invention. For those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention.

Claims

1. An automatic charging and power supply system based on radio frequency capture, characterized in that It includes an LC tuning circuit and a rectifying and collecting circuit connected to the LC tuning circuit; The LC tuning circuit includes an antenna SMA interface and a first-gear selector paddle of the antenna SMA interface, a second-gear switching circuit connected to the first-gear switching circuit, and a voltage-doubling detection circuit and a field-effect transistor circuit respectively connected to the first-gear selector paddle; The voltage-doubling detection circuit includes a first capacitor, a second capacitor, a first diode, and a second diode. One end of the first capacitor is connected to the anode of the second diode, the cathode of the second diode is connected to the second capacitor, the anode of the first diode is connected to the first capacitor and the second capacitor, and the cathode of the second diode is connected to the first capacitor and the second diode; Among them, when the input signal is in the negative half-wave, the first diode conducts, and charges are accumulated in the first capacitor; when the input signal becomes the positive half-wave, the charges accumulated in the first capacitor are loaded into the signal, doubling the output voltage, and the second capacitor undertakes the filtering function.

2. The automatic charging and power supply system based on radio frequency capture according to claim 1, wherein The first-gear switching circuit is a circuit for switching between the voltage-doubling detection circuit and the field-effect transistor circuit; in the medium-wave environment, the first-gear switching circuit is switched to the voltage-doubling circuit gear, so that the first capacitor is fully charged. When the input signal is in the negative half-wave, the first diode conducts, and charges are accumulated in the first capacitor; when the input signal becomes the positive half-wave, the charges accumulated in the first capacitor are loaded into the input signal, doubling the output voltage; if the first capacitor is not fully charged, the output voltage is much lower than twice the input voltage.

3. The automatic charging and power supply system based on radio frequency capture according to claim 1, wherein The second-gear switching circuit is a switching circuit for changing the inductance value currently connected to the LC tuning circuit; The second-gear switching circuit includes a medium-wave circuit gear and a short-wave circuit gear. The medium-wave circuit gear is used to collect electromagnetic waves of 300~30 MHz, and the short-wave circuit gear is used to collect electromagnetic waves of 3~30 MHz.

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