Passive wireless temperature measuring device and monitoring method

Abstract

The application discloses a passive wireless temperature measuring device and a monitoring method, which comprise an electromagnetic induction, a voltage doubling rectifier circuit, a voltage stabilizing circuit, a charging circuit, an LDO, a wireless receiver and a voltage monitoring circuit, the output end of the electromagnetic induction is connected with the input end of the voltage doubling rectifier circuit, the output end of the voltage doubling rectifier circuit is connected with the input end of the charging circuit through the voltage stabilizing circuit, the output end of the voltage monitoring circuit is connected with the enable input end of the LDO, and the LDO is connected with a CPU for data acquisition and transmission; the application adopts the voltage doubling rectifier circuit which is more suitable for the scene and is optimized than the full-bridge rectifier circuit, and adopts the more controllable digital circuit to replace the complex analog circuit, so that the starting current of the device is greatly reduced, meanwhile, the smart random algorithm based on the hardware characteristics is introduced to dynamically adjust the data transmission interval, and the problem of data during wireless data transmission is effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of high voltage temperature measurement technology, and in particular to a passive wireless temperature measurement device and monitoring method. Background Technology

[0002] Currently, due to the difficulty of maintaining high-voltage environments, battery-powered temperature measurement products are rare in high-voltage temperature measurement solutions. Instead, passive temperature measurement systems powered by CT induction are used. These passive temperature measurement devices are directly installed at the measurement point, and because their energy supply is continuous, they can monitor the electrical temperature of the measurement point in real time. However, the operation of the CT induction power supply device depends on the initial starting current; the lower the minimum starting current, the more immediate the monitoring. Furthermore, with an increasing number of monitoring points and very short transmission intervals, the probability of data collisions causing packet loss increases significantly.

[0003] Moreover, in scenarios with a large number of electrical nodes, when the number of monitored electrical nodes reaches hundreds or more, packet collisions can cause packet loss, making it impossible to reliably monitor all electrical nodes. This not only renders the monitoring meaningless but may also pose a safety hazard.

[0004] Therefore, how to reduce the minimum starting current of the high-voltage passive temperature measurement system and improve the communication reliability of the high-voltage passive temperature measurement system are urgent problems to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a passive wireless temperature measurement device and monitoring method, which can reduce the minimum starting current of the passive wireless temperature measurement device and effectively improve the communication reliability in the case of a large number of monitoring points.

[0006] The technical solution adopted in this invention is as follows: A passive wireless temperature measurement device includes an electromagnetic induction circuit, a voltage doubler rectifier circuit, a voltage regulator circuit, a charging circuit, an LDO (Low Voltage Regulator), a wireless receiver, and a voltage monitoring circuit. The output of the electromagnetic induction circuit is connected to the input of the voltage doubler rectifier circuit. The output of the rectifier circuit, after passing through the voltage regulator circuit, is connected to the input of the charging circuit. The output of the charging circuit is connected to the input of the voltage monitoring circuit of the LDO and a charging capacitor. The output of the voltage monitoring circuit controls the enable input of the LDO, which is also connected to the control enable pin of the CPU. The CPU performs data acquisition and transmission, and the wireless receiver receives the transmitted data. The data; the voltage doubler rectifier circuit includes a first capacitor C1, a second capacitor C2, a first diode D1, and a second diode D2. The anode of the first diode D1 and the cathode of the second diode D2 are simultaneously connected to one end of the AC circuit. The cathode of the first diode is connected to the first capacitor C1 and then to the other end of the AC circuit. Simultaneously, the anode of the second diode is connected to the second capacitor C2 and then to the other end of the AC circuit. The cathode of the first diode is grounded, and the anode of the second diode serves as the output terminal, connected to the output terminal of the voltage regulator circuit. The CPU control of the voltage monitoring circuit is connected to the LDO pin for enable output.

[0007] The wireless receiver uses a 433MHz wireless communication link for communication.

[0008] The first capacitor C1, the second capacitor C2, the first diode D1, and the second diode D2 are all Schottky barrier diodes of type 1SS357, which have extremely low voltage drop and fast reverse recovery time, and are suitable for high-efficiency low-voltage rectifier circuits.

[0009] The voltage monitoring circuit uses the SUB-1G wireless chip CC1310.

[0010] A monitoring method based on the passive wireless temperature measurement device according to claim 1 includes the following steps: A: Start the device. Each device is equipped with a unique ID and is paired and bound to the receiver for construction. Then, the device collects data and sends the wireless temperature measurement data to the receiver through a 433MHz communication link. B: After receiving the data, the receiver directly calculates the wireless transmission power of the passive wireless temperature measurement device. Based on the power level, it guides the installation position of the receiver antenna to obtain better reception performance. Furthermore, during the construction of centralized temperature measurement sites, it combines the site conditions to reasonably calculate the appropriate number of main units, and constructs and installs the centralized temperature measurement receiver main units to control costs, ensure performance, and achieve optimal resource allocation. C: Packet loss rate and restart count statistics. The receiver performs statistical analysis on the data packets of each passive wireless temperature measurement device and counts the number of device restarts in order to monitor the device in real time and assist in monitoring the operation of the on-site system. If the packet loss rate and restart count exceed the threshold, a temperature alarm event will be issued.

[0011] In step A, to prevent data collisions during transmission and ensure reliable data transmission and real-time monitoring on-site, an intelligent random transmission interval algorithm is adopted. The specific process is as follows: First, the baseline data transmission interval of the device is set to 40 seconds. When calculating the actual data transmission interval, the data transmission interval is set with the help of the chip's unique ID. When this step is completed, the data transmission interval range is 40 ± 20 seconds. Secondly, the system adopts a temperature change transmission strategy. The system monitors the temperature in real time and immediately reports the data when the temperature changes by 0.5 degrees. Temperature sampling is performed every 2 seconds. This effectively reduces the risk of data collisions during transmission and ensures reliable data transmission and real-time monitoring on site.

[0012] This invention significantly reduces the device's startup current by employing a voltage doubler rectifier circuit that is more adaptable to various scenarios and optimized compared to a full-bridge rectifier circuit, and by replacing complex analog circuits with more controllable digital circuits. At the same time, it introduces a smart random algorithm that works in conjunction with hardware characteristics to dynamically adjust the data transmission interval, effectively reducing data transmission problems during wireless data transmission.

[0013] Compared with the prior art, the beneficial effects of the present invention are that it significantly reduces the minimum start-up current of the passive wireless temperature measurement device, reaching a level far below the standard 20A (refer to NBT 42086-2016 Technical Requirements for Wireless Temperature Measurement Devices 4.3.2-d)-2) regarding the start-up current requirement, and can be as low as less than 3A, and effectively improves the communication reliability in the case of a large number of monitoring points. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the principle of the present invention; Figure 2 This is a schematic diagram of the voltage doubler rectifier circuit of the present invention; Figure 3 This is a block diagram of the voltage monitoring circuit supporting hysteresis voltage as described in this invention. Figure 4 The voltage control timing diagram described in the invention; Figure 5 This is a flowchart of the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] like Figure 1 , 2 As shown in Figure 3, this invention includes an electromagnetic induction circuit, a voltage doubler rectifier circuit, a voltage regulator circuit, a charging circuit, an LDO (Low Voltage Regulator), a wireless receiver, and a voltage monitoring circuit. The output terminal of the electromagnetic induction circuit is connected to the input terminal of the voltage doubler rectifier circuit. The output terminal of the rectifier circuit is connected to the input terminal of the charging circuit after passing through the voltage regulator circuit. The output terminal of the charging circuit is connected to the input terminal of the voltage monitoring circuit of the LDO and the charging capacitor, respectively. The output terminal of the voltage monitoring circuit is connected to the enable input terminal of the LDO, which is also connected to the control enable pin of the CPU. The CPU performs data acquisition and transmission, and the wireless receiver is used to receive the transmitted data. The voltage doubler rectifier circuit includes a first capacitor C1, a second capacitor C2, a first diode D1, and a second diode D2. The anode of the first diode D1 and the cathode of the second diode D2 are simultaneously connected to one end of the AC circuit. The cathode of the first diode is connected to the first capacitor C1 and then to the other end of the AC circuit. Simultaneously, the anode of the second diode is connected to the second capacitor C2 and then to the other end of the AC circuit. The cathode of the first diode is grounded, and the anode of the second diode serves as the output terminal, connected to the output terminal of the voltage regulator circuit. The CPU control of the voltage monitoring circuit is connected to the LDO pin for enable output.

[0018] After the LDO output is enabled, the LDO begins to output voltage, and the subsequent CPU module starts working. At this time, as energy is consumed, the voltage of the charging capacitor also drops. Once the capacitor voltage falls below the VDET of the power monitoring chip, the power monitoring chip will stop outputting. If there is no auxiliary control for enabling the LDO, the LDO will immediately stop outputting voltage, causing the subsequent CPU module to stop working. This cycle repeats, leading to difficulties in starting the subsequent CPU circuit. Unless the sensing circuit has a very large current, and the charging speed exceeds the consumption of the subsequent CPU, but even then, the minimum starting current of the CT sensing temperature measurement device cannot be guaranteed.

[0019] To address this issue, a common approach is to use the LDO's output VLDO for voltage division, which then assists in controlling the LDO's enable. This allows the LDO to maintain its output even when the charging capacitor voltage is lower than that of the power monitoring chip. However, this solution has inherent drawbacks. Due to the inherent characteristics of LDOs, within a certain voltage range, the LDO's enable pin is in an unstable output state, causing leakage current. This prevents the capacitor from fully charging and disables subsequent circuitry. Therefore, an LDO with a very narrow voltage range and very low leakage current needs to be selected, which is not only expensive but also faces the risk of shortages. Furthermore, it cannot avoid the unstable operating state caused by the LDO's inherent defects.

[0020] Therefore, this system innovatively adopts a method of using a CPU pin to assist in controlling the LDO enable. After the CPU power supply is initially completed, the CPU assists in controlling the LDO pin to output a high level, which can maintain the normal operation of the LDO, as long as the CPU's minimum operating voltage VLOW = 1.8V is met. When the LDO output voltage is lower than 1.8V, the CPU stops working, the CPU assists in controlling the LDO pin to go low, and the LDO immediately stops outputting, allowing the front-end charging circuit to charge normally. Because the CPU's minimum operating voltage VLOW is higher than the voltage of the LDO enable pin, the inherent limitations of the LDO can be avoided.

[0021] However, this method also places very high demands on the CPU: it must have low power consumption, a sufficiently fast startup speed, and operate within the hysteresis voltage range of the power monitoring chip. The CPU must also assist in controlling the LDO enable pin and provide effective output. Therefore, this system selected an ultra-high performance and ultra-low power CPU, based on TI's latest low-power SUB-1G wireless chip CC1310, and successfully implemented this technology. Specific control procedures are as follows... Figure 4 As shown, At time T1, the capacitor charging voltage reaches VDET + VHYS, triggering the power monitoring chip to output and control the LDO output. At this point, the CPU begins to operate. Due to the subsequent CPU operation, energy is consumed, and the capacitor voltage decreases accordingly.

[0022] At time T2, after the CPU starts working for time TCPU, the LDO auxiliary control pin starts outputting, and the capacitor voltage continues to decrease.

[0023] At time T3, due to the CPU's energy consumption, the capacitor's power supply is lower than VDET, and the power monitoring chip has no output. However, at this time, because the CPU's LDO auxiliary control pin outputs a high level, the LDO continues to output, and the CPU works normally.

[0024] At time T4, the CPU completes its business workflow and enters a low-power mode. At this time, the CPU consumes very little energy, the energy charged by the front-end capacitor is greater than the energy consumed by the system, and the capacitor voltage continues to increase.

[0025] At time T5, the capacitor continues to charge until the charging voltage reaches VDET + VHYS, triggering an output from the power monitoring chip. The LDO output reaches its maximum value of VLDO = 3.3V.

[0026] At time T6, due to the limitations of the voltage regulator circuit, the maximum charging voltage of the capacitor is VMAX = 5.6V.

[0027] At T7, due to the energy consumption of the CPU, the capacitor voltage begins to decrease. When the capacitor voltage begins to fall below VDET+VHYS, the power monitoring chip output begins to decrease, and the LDO output voltage begins to decrease.

[0028] At time T8, due to the CPU's energy consumption, the capacitor's power supply is lower than VDET, and the power chip has no output. However, at this time, because the CPU's LDO auxiliary control pin outputs a high level, the LDO continues to output, and the CPU works normally.

[0029] At time T9, due to the continuous consumption of CPU energy, the capacitor voltage continues to decrease. When the LDO output voltage drops below the CPU's minimum operating voltage VLOW=1.8V, the CPU immediately stops working, the LDO auxiliary control pin has no output, and the LDO immediately cuts off with no output. At this time, the capacitor voltage increases due to the operation of the electromagnetic induction power supply circuit, which increases energy.

[0030] The CT (Cellular Transformer) uses electromagnetic induction to generate an induced electromotive force (EMF) in the secondary winding. Since the primary winding is 50Hz AC, the induced signal in the secondary winding is also AC, and its energy is extremely weak, insufficient to directly power subsequent circuits. Therefore, the AC signal needs to be rectified into DC, and continuously charged to accumulate energy for the entire system to function. In a traditional full-bridge rectifier circuit, the peak voltage of the AC signal is Vpeak. Due to the single-phase conduction characteristic of diodes, in the positive half-axis of AC, the current flows through diodes D2 and D4 to form a loop, and the voltage is output through Vout, with its peak value being Vpeak. In the negative half-axis of AC, the current flows through diodes D3 and D1 to form a loop, and the voltage is output through Vout, with its peak value being Vpeak. Through the above analysis, after passing through the full-bridge rectifier circuit, the voltage in the negative half-axis becomes the voltage in the positive half-axis, completing the AC-to-DC output conversion. The peak value of the rectified waveform Vout is Vpeak.

[0031] In practical operation, the improved voltage doubler rectifier circuit of this application forms a current loop through capacitor C1 and diode D1 during the negative half-axis of AC, accumulating a half-wave voltage on capacitor C1 with a peak value of Vpeak. During the positive half-axis of AC, the voltage accumulated on capacitor C1 can be directly output through capacitor C2 to be superimposed on Vout. Adding the output of the positive half-axis of AC, the peak value of Vout is 2Vpeak. The improved voltage doubler rectifier circuit, while maintaining the same number and cost of hardware components, can significantly reduce the minimum starting current of the CT sensor-based temperature measurement device. Actual measurements show that with the same external components, the minimum starting current of the circuit using a traditional full-bridge rectifier circuit is approximately 8A, while the minimum current of the CT sensor-based temperature measurement device using the voltage doubler rectifier circuit can reach below 3A. Although both circuits can meet the standard requirement of a minimum starting current of 20A, a lower starting current improves product performance and expands the product's applicability.

[0032] Compared to traditional voltage doubler rectifier circuits, this circuit also possesses the following characteristics: during the negative AC half-axis, the current not only charges capacitor C1 but also forms a loop through D1; during the positive AC half-axis, the current also forms a loop through C2. This means the circuit can also form a loop to dissipate energy. In contrast to traditional full-bridge rectifier circuits where excess energy is dissipated as heat by the voltage regulator circuit, this circuit significantly improves system stability. It is particularly suitable for high-current scenarios, greatly enhancing product stability.

[0033] The wireless receiver uses a 433MHz wireless communication link for communication.

[0034] The first capacitor C1, the second capacitor C2, the first diode D1, and the second diode D2 are all Schottky barrier diodes of type 1SS357, which have extremely low voltage drop and fast reverse recovery time, making them suitable for high-efficiency low-voltage rectifier circuits.

[0035] The voltage monitoring circuit uses the SUB-1G wireless chip CC1310. This application employs a power monitoring chip with hysteresis support in the voltage monitoring circuit. The voltage monitoring loop monitors the real-time voltage VDD of the capacitor in the charging circuit. Based on the performance of the induction coil rectifier circuit, this circuit selects a power monitoring chip with a VDET of 3.3V, whose hysteresis voltage VHYS is VDET*0.05 = 0.165V. Figure 3 As shown, ① When the VDD voltage reaches VDET+VHYS, the power monitoring chip outputs a high level to control the LDO to output power. After the LDO outputs power, the subsequent CPU circuit starts to work. Due to energy consumption, VDD will inevitably drop.

[0036] ② When the VDD voltage is lower than VDET + VHYS, VOH also decreases, but it can still continuously output a high level. Only when the VDD voltage is lower than VDET will the power monitoring chip stop outputting, which is the level VOL. The continuous output of the LDO cannot be controlled. If no other control method is applied to the LDO, the subsequent stage will immediately shut down.

[0037] ③ When the VDD voltage is detected to recover to VDET+VHYS, the power monitoring version continues to output a high level to control the LDO output.

[0038] A monitoring method based on the passive wireless temperature measurement device according to claim 1, such as Figure 5 As shown, it includes the following steps: A: Start the device. Each device is equipped with a unique ID and is paired and bound to the receiver for construction. Then, the data collected by the device is collected. The CPU of the voltage monitoring circuit sends the wireless temperature measurement data to the receiver through a wireless 433MHz communication link. B: After receiving the data, the receiver directly calculates the wireless transmission power of the passive wireless temperature measurement device. Based on the power level, it guides the installation position of the receiver antenna to obtain better reception performance. Furthermore, during the construction of centralized temperature measurement sites, it combines the site conditions to reasonably calculate the appropriate number of main units, and constructs and installs the centralized temperature measurement receiver main units to control costs, ensure performance, and achieve optimal resource allocation. C: Packet loss rate and restart count statistics. The receiver performs statistical analysis on the data packets of each passive wireless temperature measurement device and counts the number of device restarts in order to monitor the device in real time and assist in monitoring the operation of the on-site system. If the packet loss rate and restart count exceed the threshold, a temperature alarm event will be issued.

[0039] In step A, to prevent data collisions during transmission and ensure reliable data transmission and real-time monitoring on-site, an intelligent random transmission interval algorithm is adopted. The specific process is as follows: First, the baseline data transmission interval of the device is set to 40 seconds. When calculating the actual data transmission interval, the data transmission interval is set with the help of the chip's unique ID. When this step is completed, the data transmission interval range is 40 ± 20 seconds. Secondly, the system adopts a temperature change transmission strategy. The system monitors the temperature in real time and immediately reports the data when the temperature changes by 0.5 degrees. Temperature sampling is performed every 2 seconds. This effectively reduces the risk of data collisions during transmission and ensures reliable data transmission and real-time monitoring on site.

[0040] In the existing technology, due to hardware limitations, the power supply of wireless temperature measurement devices is obtained by charging capacitors with energy from electromagnetic induction. Due to structural and hardware limitations, its capacity is extremely limited, so it cannot sustain the continuous operation of the CPU. Therefore, after the CPU completes temperature sampling and wireless data transmission, it needs to immediately enter a low-power mode so that the energy in the capacitor can continue to increase to maintain the continuous operation of the device.

[0041] Because of the continuous energy source, the passive wireless temperature measurement device based on electromagnetic induction can have a very short data transmission interval. It can meet the requirement of less than 60 seconds of transmission interval with the minimum starting current. Therefore, it can provide real-time monitoring of the monitored part and there is no need to worry about the power supply life. It can achieve the standard of lifelong maintenance-free operation.

[0042] Therefore, passive wireless temperature measurement devices based on electromagnetic induction generally employ a single-transmit, single-receive data transmission strategy, using shorter data transmission intervals to achieve reliable data transmission. Based on this, this system further improves the overall performance of the product through the aforementioned algorithm.

[0043] Data flow: Since the data from the passive wireless temperature measurement device cannot be directly displayed or provide audible and visual alarms, the data must first be transmitted to the receiver, and then the receiver will process and apply the data. This system uses a 433MHz wireless communication link as the data transmission channel.

[0044] Simplified construction and intelligent pairing: The electromagnetic induction passive wireless temperature measurement device is equipped with a unique ID at the factory. During use, the construction personnel install the passive wireless temperature measurement device and receiver on site to bind them together, and can name the monitored areas. When the receiver receives data from multiple passive wireless temperature measurement devices, it can determine whether the data belongs to the device it is bound to. If it does, it is processed; otherwise, it is discarded.

[0045] This mechanism is suitable for scenarios with multiple receivers on site. Each receiver only processes the temperature measuring device it is bound to, ensuring the accuracy and reliability of the monitoring.

[0046] Reasonable task allocation: Traditional battery-powered temperature measuring devices not only monitor temperature in real time but also need to handle temperature alarm events such as over-temperature and temperature rise. This is because handling over-temperature events requires setting temperature over-limit values ​​to provide more reliable event generation. However, because these are low-power battery-powered devices, setting temperature over-limit values ​​on-site is extremely difficult; manufacturers generally do not support changes, instead providing default values ​​at the factory. Therefore, battery-powered temperature measuring devices may generate events irrationally—failing to generate events when they should, generating events when they shouldn't, and even experiencing event loss due to packet loss during data transmission, failing to provide reliable real-time monitoring.

[0047] Electromagnetic induction passive wireless temperature measurement devices can fully utilize their operating characteristics and rationally allocate tasks. In this system, the device only performs temperature sampling and data transmission; temperature-related events are handled by the receiver. Therefore, temperature-related events can be configured during construction or on the monitoring and maintenance platform to ensure stronger environmental adaptability.

[0048] It can also effectively avoid the problem of event loss caused by data collisions during data transmission.

[0049] Intelligent Data Transmission Strategy: This system uses 433MHz wireless communication for its data link, with a one-to-one transmission and reception direction. Since there is no interaction during data transmission, auxiliary methods are needed to ensure reliable data communication. When multiple passive wireless temperature measurement devices are present, each device uploads data according to its own logic, which increases the probability of data transmission collisions and data loss. Therefore, this system introduces the aforementioned intelligent random transmission interval algorithm, which significantly reduces the probability of data collisions. Secondly, the system employs a temperature change reporting strategy. The system monitors the temperature in real time and immediately reports data when the temperature changes by 0.5 degrees Celsius. Due to the uncertainty of the on-site temperature, data may be uploaded at any time. Frequent data uploads will inevitably deplete the energy in the capacitor, causing the device to restart. However, due to the continuous energy source, the restarted device continues to operate reliably. To reduce the excessively frequent data reporting and its consumption of wireless resources, this system innovatively reduces the temperature sampling frequency, setting it to be once every 2 seconds. By adopting these two data transmission strategies, the concept of data collisions during transmission is effectively reduced, ensuring reliable data transmission and real-time monitoring on-site.

[0050] The passive wireless temperature measurement device based on electromagnetic induction uses a 433MHz wireless communication link for communication. The device is usually installed in dangerous areas such as high voltage. This system can monitor the status of the device through the above method to assist on-site construction and view the status of the device in real time, thus realizing a high-performance and more stable high-voltage testing device.

[0051] In the description of this invention, it should be noted that for directional terms, such as "center," "lateral," and "vertical," the appropriate terms may be used. The directions and positional relationships indicated by symbols such as "direction", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of the present invention.

[0052] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0053] Note that the above description is merely a preferred embodiment and application of the technical principles of the present invention. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the specific embodiments described herein, and may include many other effective embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A passive wireless temperature measurement device, characterized in that: The system includes an electromagnetic induction circuit, a voltage doubler rectifier circuit, a voltage regulator circuit, a charging circuit, an LDO (Low Voltage Regulator), a wireless receiver, and a voltage monitoring circuit. The output of the electromagnetic induction circuit is connected to the input of the voltage doubler rectifier circuit. The output of the rectifier circuit, after passing through the voltage regulator circuit, is connected to the input of the charging circuit. The output of the charging circuit is connected to the input of the LDO's voltage monitoring circuit and the charging capacitor. The output of the voltage monitoring circuit controls the enable input of the LDO, which is also connected to the CPU's control enable pin. The CPU performs data acquisition and transmission, and the wireless receiver receives the transmitted data. The voltage doubler rectifier circuit includes a first capacitor C1, a second capacitor C2, and a third capacitor C3. Capacitor C2 is connected to a first diode D1 and a second diode D2. The anode of the first diode D1 and the cathode of the second diode D2 are simultaneously connected to one end of the AC circuit. The cathode of the first diode is connected to the first capacitor C1 and then to the other end of the AC circuit. Simultaneously, the anode of the second diode is connected to the second capacitor C2 and then to the other end of the AC circuit. The cathode of the first diode is grounded, and the anode of the second diode serves as the output terminal, connected to the output terminal of the voltage regulator circuit. The CPU control of the voltage monitoring circuit is connected to the LDO pin for enable output. When the capacitor voltage is lower than VDET of the power monitoring chip, the power monitoring chip will have no output. The CPU auxiliary control LDO pin outputs a high level to maintain normal LDO operation, as long as the CPU's minimum operating voltage VLOW = 1.8V is met. When the LDO output voltage is lower than 1.8V, the CPU stops working, and the CPU auxiliary control LDO pin is at a low level. At this time, the LDO immediately has no output, and the pre-charging circuit can charge normally.

2. The passive wireless temperature measurement device according to claim 1, characterized in that: The wireless receiver uses a 433MHz wireless communication link for communication.

3. The passive wireless temperature measurement device according to claim 2, characterized in that: The first capacitor C1, the second capacitor C2, the first diode D1, and the second diode D2 are all Schottky barrier diodes of type 1SS357, which have extremely low voltage drop and fast reverse recovery time, and are suitable for high-efficiency low-voltage rectifier circuits.

4. The passive wireless temperature measurement device according to claim 3, characterized in that: The voltage monitoring circuit uses the SUB-1G wireless chip CC1310.

5. A monitoring method based on the passive wireless temperature measurement device according to claim 1, characterized in that, Includes the following steps: A: Start the device. Each device is equipped with a unique ID and is paired and bound to the receiver for construction. Then, the device collects data and sends the wireless temperature measurement data to the receiver through a 433MHz communication link. B: After receiving the data, the receiver directly calculates the wireless transmission power of the passive wireless temperature measurement device. Based on the power level, it guides the installation position of the receiver antenna to obtain better reception performance. Furthermore, during the construction of centralized temperature measurement sites, it combines the site conditions to reasonably calculate the appropriate number of main units, and constructs and installs the centralized temperature measurement receiver main units to control costs, ensure performance, and achieve optimal resource allocation. C: Packet loss rate and restart count statistics. The receiver performs statistical analysis on the data packets of each passive wireless temperature measurement device and counts the number of device restarts in order to monitor the device in real time and assist in monitoring the operation of the on-site system. If the packet loss rate and restart count exceed the threshold, a temperature alarm event will be issued.

6. The passive wireless temperature measurement monitoring method according to claim 5, characterized in that: In step A, to prevent data collisions during transmission and ensure reliable data transmission and real-time monitoring on-site, an intelligent random transmission interval algorithm is adopted. The specific process is as follows: First, the baseline data transmission interval of the device is set to 40 seconds. When calculating the actual data transmission interval, the data transmission interval is set with the help of the chip's unique ID. When this step is completed, the data transmission interval range is 40 ± 20 seconds. Secondly, the system adopts a temperature change transmission strategy. The system monitors the temperature in real time and immediately reports the data when the temperature changes by 0.5 degrees. Temperature sampling is performed every 2 seconds. This effectively reduces the risk of data collisions during transmission and ensures reliable data transmission and real-time monitoring on site.

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