Current sampling circuit, its sampling voltage compensation method and motor monitoring system

Abstract

This application provides a current sampling circuit, its sampling voltage compensation method, and a motor monitoring system. The current sampling circuit includes: a current sampling branch connected to the output terminal of a current sensor for sampling the current flowing through the motor, the current sampling branch being used to scale the voltage signal output by the current sensor to obtain a first sampling voltage signal; a temperature sampling branch connected to the output terminal of the current sensor, the temperature sampling branch being used to sample the voltage across a thermistor to obtain a second sampling voltage signal; and a processing unit connected to the current sampling branch and the temperature sampling branch respectively, the processing unit being used to compensate the first sampling voltage signal using the second sampling voltage signal to obtain a target sampling voltage signal, thus solving the problem of low measurement accuracy in existing current sampling circuits.

Description

Technical Field

[0001] This application relates to the field of current sampling circuit technology, and more specifically, to a current sampling circuit, its compensation method, and a motor monitoring system. Background Technology

[0002] Accurate and reliable sampling of motor current is the foundation for optimizing system efficiency, monitoring status, and providing reliable protection.

[0003] However, the current sampling circuits in the prior art have the following main problems:

[0004] 1. Temperature Drift Issue: The output signal of the current sensor and the characteristics of components in the subsequent current sampling circuit (such as operational amplifiers and resistors) will drift with changes in ambient temperature. For example, the sensor's sensitivity, zero-point offset, and the input offset voltage of the operational amplifier are all temperature-dependent. This can cause deviations in the sampled voltage signal under different temperature conditions, even if the actual current remains constant, thus affecting measurement accuracy.

[0005] 2. Lack of fault diagnosis capability: Traditional current sampling circuits typically only provide an analog voltage signal and cannot actively determine their own or the sensor's operating status. When a sensor experiences an open circuit, short circuit, or damage, or when the power supply is abnormal, the circuit may output an incorrect voltage value. However, the system cannot identify whether this is a "normal current" or a "fault signal," leading to protection function failure or malfunction, thus reducing the system's reliability.

[0006] The aforementioned problems collectively result in insufficient measurement accuracy and system reliability of existing current sampling schemes under wide temperature ranges and complex operating conditions. Therefore, there is an urgent need for a current sampling circuit that can automatically compensate for temperature effects and effectively diagnose its own operating status to improve the accuracy of current measurement and the overall reliability of the system. Summary of the Invention

[0007] The main objective of this application is to provide a current sampling circuit, its compensation method, and a motor monitoring system to at least solve the problem of low measurement accuracy of current sampling circuits in the prior art.

[0008] To achieve the above objectives, according to one aspect of this application, a current sampling circuit is provided, comprising: a current sampling branch connected to the output terminal of a current sensor for sampling the current flowing through a motor, the current sampling branch being used to scale the voltage signal output by the current sensor to obtain a first sampling voltage signal; a temperature sampling branch connected to the output terminal of the current sensor, the temperature sampling branch being used to sample the voltage across a thermistor to obtain a second sampling voltage signal; and a processing unit connected to the current sampling branch and the temperature sampling branch respectively, the processing unit being used to compensate the first sampling voltage signal using the second sampling voltage signal to obtain a target sampling voltage signal.

[0009] Optionally, the current sampling branch further includes a differential amplifier connected to the output terminal of the current sensor, wherein the differential amplifier is used to scale the voltage signal output by the current sensor to obtain the first sampled voltage signal.

[0010] Optionally, the temperature sampling branch includes a voltage divider circuit, comprising a voltage divider device and a thermistor connected in series, one end of the voltage divider device being connected to the power output terminal, one end of the thermistor device being grounded, and the common terminal of the voltage divider device and the thermistor device being connected to the processing unit.

[0011] Optionally, the current sampling branch further includes a protection device, which is used to clamp the first sampled voltage signal to the safe voltage range of the processing unit.

[0012] Optionally, the current sampling branch further includes: a first operational amplifier, wherein the non-inverting input terminal of the first operational amplifier is connected to the positive output terminal of the current sensor, the inverting input terminal of the first operational amplifier is connected to the output terminal of the first operational amplifier, and the output terminal of the first operational amplifier is connected to the non-inverting input terminal of the differential amplifier.

[0013] Optionally, the current sampling circuit further includes a pull-up resistor, one end of which is connected to the output terminal of the current sensor, and the other end of which is connected to the power supply output terminal.

[0014] According to another aspect of this application, a sampling voltage compensation method for a current sampling circuit is provided, applied to the current sampling circuit, the method comprising: acquiring the current ambient temperature of the space where the motor is located at the current moment, a first sampling voltage signal, and a second sampling voltage signal; calculating a compensation voltage based on the current ambient temperature and the second sampling voltage signal at the current moment, the compensation voltage being the voltage offset caused by the current ambient temperature; and calculating the sum of the first sampling voltage signal at the current moment and the compensation voltage to obtain a target sampling voltage signal.

[0015] Optionally, calculating the compensation voltage based on the current ambient temperature and the second sampled voltage signal at the current moment includes: calculating the difference between the current ambient temperature and the reference temperature to obtain a temperature difference; acquiring the second sampled voltage signals corresponding to multiple test ambient temperatures when the motor is stopped; determining the temperature drift rate based on the second sampled voltage signals corresponding to the multiple test ambient temperatures, wherein the temperature drift rate is the rate at which the second sampled voltage signal changes with the ambient temperature; and calculating the product of the temperature drift rate and the temperature difference to obtain the compensation voltage.

[0016] Optionally, after calculating the sum of the first sampled voltage signal and the compensation voltage at the current moment to obtain the target sampled voltage signal, the method further includes: obtaining a normal voltage range, wherein the normal voltage range is the voltage interval in which the current sensor operates without fault and the motor stops running; determining that the current sensor has an open circuit fault when the target sampled voltage signal is greater than the maximum value of the normal voltage range; and determining that the current sensor has a short circuit fault when the target sampled voltage signal is less than the minimum value of the normal voltage range.

[0017] According to another aspect of this application, a motor monitoring system is provided, including a motor and the current sampling circuit.

[0018] By applying the technical solution of this application, in the above-mentioned current sampling circuit, the voltage signal output by the current sensor is scaled by the current sampling branch to obtain a first sampling voltage signal within a suitable range. The second sampling voltage signal is obtained by sampling the voltage division of the thermistor by the temperature sampling branch. The voltage deviation caused by the ambient temperature can be determined. The processing unit processes the second sampling voltage signal and the first sampling voltage signal to compensate for the first sampling voltage signal and obtain the target sampling voltage signal. This overcomes the problem that the voltage deviation caused by the ambient temperature affects the measurement accuracy, thus solving the problem of low measurement accuracy of the current sampling circuit in the prior art. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0020] Figure 1 A schematic diagram of a current sampling branch provided in an embodiment of this application is shown;

[0021] Figure 2 A schematic diagram of a temperature sampling branch provided in an embodiment of this application is shown;

[0022] Figure 3 A graph showing the relationship between voltage and temperature at point D according to an embodiment of this application is shown.

[0023] Figure 4 A schematic diagram of a processing unit provided in an embodiment of this application is shown;

[0024] Figure 5 A schematic flowchart of a sampling voltage compensation method for a current sampling circuit according to an embodiment of this application is shown.

[0025] Figure 6 A waveform diagram of the static output voltage of a current sensor provided according to an embodiment of this application is shown;

[0026] Figure 7 The diagram shows the waveform of the open-circuit voltage at point A of a current sensor according to an embodiment of this application;

[0027] Figure 8 The diagram shows a waveform of the voltage at point A when a current sensor is short-circuited, according to an embodiment of this application. Detailed Implementation

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0030] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0031] As described in the background section, the measurement accuracy of current sampling circuits in the prior art is low. To solve this problem, embodiments of this application provide a current sampling circuit, its compensation method, and a motor monitoring system.

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0033] This embodiment provides a current sampling circuit, including:

[0034] The current sampling branch is connected to the output terminal of a current sensor used to sample the current flowing through the motor. The current sampling branch is used to scale the voltage signal output by the current sensor to obtain a first sampled voltage signal.

[0035] The temperature sampling branch is connected to the output terminal of the current sensor mentioned above. The temperature sampling branch is used to sample the voltage across the two ends of the thermistor to obtain a second sampling voltage signal.

[0036] The processing unit is connected to the current sampling branch and the temperature sampling branch respectively. The processing unit is used to compensate the first sampling voltage signal with the second sampling voltage signal to obtain the target sampling voltage signal.

[0037] In the aforementioned current sampling circuit, the voltage signal output by the current sensor is scaled by the current sampling branch to obtain a first sampling voltage signal within a suitable range. The second sampling voltage signal is obtained by sampling the voltage divider of the thermistor through the temperature sampling branch. This allows the determination of the voltage deviation caused by the ambient temperature. The processing unit then processes the second and first sampling voltage signals to compensate for the first sampling voltage signal and obtain the target sampling voltage signal. This overcomes the problem of voltage deviation caused by ambient temperature affecting measurement accuracy, thus solving the problem of low measurement accuracy in current sampling circuits in the prior art.

[0038] In one alternative implementation, such as Figure 1 As shown, the aforementioned current sampling branch also includes:

[0039] A differential amplifier is connected to the output terminal of the current sensor. The differential amplifier is used to scale the voltage signal output by the current sensor to obtain the first sampled voltage signal.

[0040] The first operational amplifier U1 has its non-inverting input terminal connected to the positive output terminal of the current sensor, its inverting input terminal connected to its output terminal, and its output terminal connected to the non-inverting input terminal of the differential amplifier.

[0041] In the above embodiment, the first operational amplifier U1 forms a voltage follower, ensuring that its output voltage equals the input voltage at the non-inverting input terminal, i.e., the voltage at point A equals the voltage at the positive output terminal of the current sensor. This isolates and buffers the signal. Resistors R2, R3, R4, and R5, together with the second operational amplifier U2, form a differential amplifier. Resistors R2 and R3 provide input resistance, ensuring the differential amplifier operates normally under a 5V power supply. R4 and R5 are part of the feedback network, and together with R2 and R3, they determine the amplifier gain. Specifically, the op-amp gain can be approximated as R5 / R3. By selecting appropriate resistor values, the input voltage signal can be scaled to a range suitable for subsequent processing, resulting in the aforementioned first sampled voltage signal. Capacitors C1 and C2 are used to bypass the feedback resistor and input resistor, respectively, to suppress high-frequency noise and improve circuit stability. The amplified and filtered current signal is further filtered by resistor R6 and capacitor C3.

[0042] In one alternative implementation, such as Figure 2 As shown, the temperature sampling branch mentioned above includes:

[0043] The voltage divider circuit includes a voltage divider device R7 and a thermistor R8 connected in series. One end of the voltage divider device R7 is connected to the power output terminal, and one end of the thermistor R8 is grounded. The common terminal of the voltage divider device R7 and the thermistor R8 is connected to the processing unit.

[0044] In the above embodiment, a voltage divider circuit is formed by connecting a thermistor R8 and a voltage divider R7 in series, and the output of this voltage divider circuit is point D. Therefore, the voltage at point D is sampled and processed, and this voltage changes with temperature. When the ambient temperature rises, the resistance of the thermistor increases or decreases, causing the voltage at point D to rise. Conversely, when the temperature decreases, the voltage at point D decreases. The relationship between the voltage at point D and temperature is shown in the graph below. Figure 3 As shown.

[0045] In one alternative implementation, such as Figure 1 As shown, the current sampling branch also includes a protection device, which is used to clamp the first sampling voltage signal to the safe voltage range of the processing unit.

[0046] In the above embodiment, diodes D1 and D2 form a clamping circuit, i.e., a protection device, to protect subsequent processing units (such as MCUs). Diode D1 clamps the upper limit of the output voltage to 3.3V to prevent overvoltage damage; diode D2 clamps the lower limit of the output voltage to 0V to prevent negative voltage damage. This makes the circuit safely compatible with processing units operating at 3.3V logic levels. Finally, the amplified and protected first sampled voltage signal is output through point C for analysis and processing by subsequent processing units.

[0047] In addition, such as Figure 4 As shown, the processing unit is an MCU, and the voltage signals output from points C and D are sent to the MCU for analysis and processing.

[0048] In one alternative implementation, such as Figure 1 As shown, the above current sampling circuit also includes:

[0049] Pull-up resistor R0, one end of which is connected to the output terminal of the current sensor, and the other end of which is connected to the power output terminal.

[0050] In the above implementation, the pull-up resistor R0 ensures that the signal line remains at a high level when it is not actively driven, thereby avoiding the uncertain state caused by the signal floating.

[0051] This embodiment provides a sampling voltage compensation method for a current sampling circuit running on a mobile terminal, computer terminal, or similar computing device. It is applied to the aforementioned current sampling circuit. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0052] Figure 5 This is a flowchart of a sampling voltage compensation method for a current sampling circuit according to an embodiment of this application. Figure 5 As shown, the method includes the following steps:

[0053] Step S201: Obtain the current ambient temperature, first sampled voltage signal, and second sampled voltage signal of the space where the motor is located at the current moment;

[0054] Step S202: Calculate the compensation voltage based on the current ambient temperature and the second sampled voltage signal at the current moment. The compensation voltage is the voltage offset caused by the current ambient temperature.

[0055] Step S203: Calculate the sum of the first sampled voltage signal and the compensation voltage at the current moment to obtain the target sampled voltage signal.

[0056] In the sampling voltage compensation method of the above current sampling circuit, the resistance of the thermistor changes due to temperature changes, which in turn causes a change in the voltage across the thermistor, i.e., a change in the second sampling voltage signal. The voltage offset caused by the current ambient temperature, i.e., the compensation voltage, can be determined by the second sampling voltage signal and the current ambient temperature. The sum of the first sampling voltage signal and the compensation voltage at the current moment is calculated to obtain the target sampling voltage signal, thus completing the voltage compensation and solving the problem of decreased measurement accuracy of the current sampling circuit caused by temperature drift.

[0057] In one optional implementation, step S202 includes:

[0058] Step S2021: Calculate the difference between the current ambient temperature and the reference temperature to obtain the temperature difference.

[0059] Step S2022: When the motor stops running, acquire the second sampling voltage signals corresponding to multiple test ambient temperatures;

[0060] Step S2023: Determine the temperature drift rate based on the second sampled voltage signals corresponding to multiple test ambient temperatures. The temperature drift rate is the rate at which the second sampled voltage signal changes with the ambient temperature.

[0061] Step S2024: Calculate the product of the temperature drift rate and the temperature difference to obtain the compensation voltage.

[0062] In the above implementation, by embedding the temperature and voltage formula T=kV in the processing unit (MCU), the current ambient temperature can be detected in real time, where k is related to the characteristics of the thermistor. Specifically, the compensation method is as follows: Before the motor runs, the output voltage at point C of the current sampling branch is the output voltage of the sampling circuit under the influence of temperature drift at the test ambient temperature, denoted as x0. By setting the reference temperature (25℃) in the processor, the output voltage x1 of the sampling circuit is obtained, which is the sampling voltage of the first sampling voltage signal. Therefore, the temperature drift rate of the sampling circuit is Tc=(x0-x1) / (T 测 -25). By real-time monitoring of the motor's operating environment temperature, the voltage difference Δy=Tc between the current sampling circuit output value and the actual voltage value under temperature influence can be calculated. (T 当前 -25). Therefore, the voltage + Δy sampled by the processing unit at point C is the actual voltage value, representing the accurate current signal obtained after temperature compensation, realizing adaptive and high-precision compensation for temperature drift of the current sampling circuit.

[0063] In an optional implementation, after calculating the sum of the first sampled voltage signal and the compensation voltage at the current moment to obtain the target sampled voltage signal, the method further includes:

[0064] Step S301: Obtain the normal voltage range, which is the voltage range in which the current sensor operates without fault and the motor stops running.

[0065] Step S302: If the target sampling voltage signal is greater than the maximum value of the normal voltage range, it is determined that the current sensor has an open circuit fault.

[0066] Step S303: If the target sampling voltage signal is less than the minimum value of the normal voltage range, it is determined that the current sensor has a short circuit fault.

[0067] In the above implementation, when the current sensor is normal and the motor is stopped, the voltage at point A will be within the expected voltage value (2.5V), such as... Figure 6 As shown; when the current sensor experiences an open-circuit fault, the voltage at point A will be abnormal (5V), as shown. Figure 7 As shown; when the current sensor experiences a short circuit fault, the voltage at point A will be abnormal (0V), as shown. Figure 8 As shown. During normal operation, U1 and U2 perform precise calculations on the input voltage to ensure the accuracy of the output signal. When a fault occurs, the output voltage of U2 exceeds the normal range (0.3-3V). The fault diagnosis unit (D1, D2) acts as a "safety valve," taking over the circuit output in the event of a serious fault and forcibly pulling it to a clearly abnormal state (3.3V or 0V), thereby triggering system protection.

[0068] This application also provides a motor monitoring system, including a motor and a current sampling circuit. It should be noted that the processing unit of the current sampling circuit in this application embodiment can be used to execute the sampling voltage compensation method for the current sampling circuit provided in this application embodiment. This device is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0069] The processing unit of the current sampling circuit provided in the embodiments of this application is described below. The processing unit of the current sampling circuit includes:

[0070] The first acquisition module is used to acquire the current ambient temperature of the space where the motor is located, the first sampled voltage signal, and the second sampled voltage signal at the current moment.

[0071] The first calculation module is used to calculate the compensation voltage based on the current ambient temperature and the second sampled voltage signal at the current time. The compensation voltage is the voltage offset caused by the current ambient temperature.

[0072] The second calculation module is used to calculate the sum of the first sampled voltage signal and the compensation voltage at the current moment to obtain the target sampled voltage signal.

[0073] In the processing unit of the aforementioned current sampling circuit, the resistance of the thermistor changes due to temperature changes, which in turn causes a change in the voltage across the thermistor, i.e., a change in the second sampling voltage signal. The voltage offset caused by the current ambient temperature, i.e., the compensation voltage, can be determined by the second sampling voltage signal and the current ambient temperature. The sum of the first sampling voltage signal and the compensation voltage at the current moment is calculated to obtain the target sampling voltage signal, thus completing voltage compensation and solving the problem of decreased measurement accuracy of the current sampling circuit caused by temperature drift.

[0074] In one optional implementation, the first computing module includes:

[0075] The first calculation submodule is used to calculate the difference between the current ambient temperature and the reference temperature to obtain the temperature difference.

[0076] The acquisition submodule is used to acquire the second sampling voltage signals corresponding to multiple test environment temperatures when the motor stops running.

[0077] The determination submodule is used to determine the temperature drift rate based on the second sampled voltage signal corresponding to multiple test ambient temperatures. The temperature drift rate is the rate at which the second sampled voltage signal changes with the ambient temperature.

[0078] The second calculation submodule is used to calculate the product of the temperature drift rate and the temperature difference to obtain the compensation voltage.

[0079] In the above implementation, by embedding the temperature and voltage formula T=kV in the processing unit (MCU), the current ambient temperature can be detected in real time, where k is related to the characteristics of the thermistor. Specifically, the compensation method is as follows: Before the motor runs, the output voltage at point C of the current sampling branch is the output voltage of the sampling circuit under the influence of temperature drift at the test ambient temperature, denoted as x0. By setting the reference temperature (25℃) in the processor, the output voltage x1 of the sampling circuit is obtained, which is the sampling voltage of the first sampling voltage signal. Therefore, the temperature drift rate of the sampling circuit is Tc=(x0-x1) / (T 测 -25). By real-time monitoring of the motor's operating environment temperature, the voltage difference Δy=Tc between the current sampling circuit output value and the actual voltage value under temperature influence can be calculated. (T 当前-25). Therefore, the voltage + Δy sampled by the processing unit at point C is the actual voltage value, representing the accurate current signal obtained after temperature compensation, realizing adaptive and high-precision compensation for temperature drift of the current sampling circuit.

[0080] In an optional embodiment, the processing unit of the current sampling circuit further includes:

[0081] The second acquisition module is used to calculate the sum of the first sampled voltage signal and the compensation voltage at the current moment to obtain the target sampled voltage signal, and then acquire the normal voltage range, which is the voltage range in which the current sensor operates without fault and the motor stops running.

[0082] The first determining module is used to determine that the current sensor has an open circuit fault when the target sampled voltage signal is greater than the maximum value of the normal voltage range.

[0083] The second determining module is used to determine that the current sensor has a short-circuit fault when the target sampled voltage signal is less than the minimum value of the normal voltage range.

[0084] In the above implementation, when the current sensor is normal and the motor is stopped, the voltage at point A will be within the expected voltage value (2.5V), such as... Figure 6 As shown; when the current sensor experiences an open-circuit fault, the voltage at point A will be abnormal (5V), as shown. Figure 7 As shown; when the current sensor experiences a short circuit fault, the voltage at point A will be abnormal (0V), as shown. Figure 8 As shown. During normal operation, U1 and U2 perform precise calculations on the input voltage to ensure the accuracy of the output signal. When a fault occurs, the output voltage of U2 exceeds the normal range (0.3-3V). The fault diagnosis unit (D1, D2) acts as a "safety valve," taking over the circuit output in the event of a serious fault and forcibly pulling it to a clearly abnormal state (3.3V or 0V), thereby triggering system protection.

[0085] It is obvious to those skilled in the art that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. They can be implemented using computer-executable program code, and thus can be stored in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those described herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0086] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0087] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0088] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0089] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0090] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0091] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0092] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0093] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0094] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0095] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0096] 1) In the current sampling circuit of this application, the voltage signal output by the current sensor is scaled by the current sampling branch to obtain a first sampling voltage signal within a suitable range. The second sampling voltage signal is obtained by sampling the voltage division of the thermistor by the temperature sampling branch. The voltage deviation caused by the ambient temperature can be determined. The processing unit processes the second sampling voltage signal and the first sampling voltage signal to compensate the first sampling voltage signal and obtain the target sampling voltage signal. This overcomes the problem that the voltage deviation caused by the ambient temperature affects the measurement accuracy, thus solving the problem of low measurement accuracy of the current sampling circuit in the prior art.

[0097] 2) In the sampling voltage compensation method of the current sampling circuit of this application, the resistance of the thermistor changes due to temperature changes, which in turn causes the voltage across the thermistor to change, i.e., the second sampling voltage signal changes. The voltage offset caused by the current ambient temperature can be determined by the second sampling voltage signal and the current ambient temperature, i.e., the compensation voltage. The sum of the first sampling voltage signal and the compensation voltage at the current moment is calculated to obtain the target sampling voltage signal, thus completing the voltage compensation and solving the problem of decreased measurement accuracy of the current sampling circuit caused by temperature drift.

[0098] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A current sampling circuit, characterized in that, include: A current sampling branch is connected to the output terminal of a current sensor used to sample the current flowing through the motor. The current sampling branch is used to scale the voltage signal output by the current sensor to obtain a first sampled voltage signal. A temperature sampling branch is connected to the output terminal of the current sensor. The temperature sampling branch is used to sample the voltage across the thermistor to obtain a second sampling voltage signal. The processing unit is connected to the current sampling branch and the temperature sampling branch respectively. The processing unit is used to compensate the first sampling voltage signal with the second sampling voltage signal to obtain the target sampling voltage signal.

2. The current sampling circuit according to claim 1, characterized in that, The current sampling branch also includes: A differential amplifier is connected to the output terminal of the current sensor. The differential amplifier is used to scale the voltage signal output by the current sensor to obtain the first sampled voltage signal.

3. The current sampling circuit according to claim 1, characterized in that, The temperature sampling branch includes: The voltage divider circuit includes a voltage divider device and a thermistor connected in series. One end of the voltage divider device is connected to the power output terminal, one end of the thermistor device is grounded, and the common terminal of the voltage divider device and the thermistor device is connected to the processing unit.

4. The current sampling circuit according to claim 1, characterized in that, The current sampling branch also includes a protection device, which is used to clamp the first sampled voltage signal to the safe voltage range of the processing unit.

5. The current sampling circuit according to claim 2, characterized in that, The current sampling branch also includes: A first operational amplifier, wherein the non-inverting input terminal of the first operational amplifier is connected to the positive output terminal of the current sensor, the inverting input terminal of the first operational amplifier is connected to the output terminal of the first operational amplifier, and the output terminal of the first operational amplifier is connected to the non-inverting input terminal of the differential amplifier.

6. The current sampling circuit according to claim 1, characterized in that, The current sampling circuit also includes: A pull-up resistor is provided, with one end connected to the output terminal of the current sensor and the other end connected to the power output terminal.

7. A sampling voltage compensation method for a current sampling circuit, applied to the current sampling circuit according to any one of claims 1 to 6, characterized in that, The method includes: Obtain the current ambient temperature, first sampled voltage signal, and second sampled voltage signal of the space where the motor is located at the current moment; The compensation voltage is calculated based on the current ambient temperature and the second sampled voltage signal at the current moment, and the compensation voltage is the voltage offset caused by the current ambient temperature; The target sampled voltage signal is obtained by calculating the sum of the first sampled voltage signal and the compensation voltage at the current moment.

8. The method according to claim 7, characterized in that, The compensation voltage is calculated based on the current ambient temperature and the second sampled voltage signal at the current moment, including: Calculate the difference between the current ambient temperature and the reference temperature to obtain the temperature difference. With the motor stopped running, the second sampling voltage signals corresponding to multiple test ambient temperatures are acquired; The temperature drift rate is determined based on the second sampled voltage signal corresponding to multiple test ambient temperatures, wherein the temperature drift rate is the rate at which the second sampled voltage signal changes with the ambient temperature. The compensation voltage is obtained by calculating the product of the temperature drift rate and the temperature difference.

9. The method according to claim 7, characterized in that, After calculating the sum of the first sampled voltage signal and the compensation voltage at the current moment to obtain the target sampled voltage signal, the method further includes: Obtain the normal voltage range, which is the voltage range in which the current sensor operates without fault and the motor stops running; If the target sampled voltage signal is greater than the maximum value of the normal voltage range, it is determined that the current sensor has an open circuit fault. If the target sampled voltage signal is less than the minimum value of the normal voltage range, it is determined that the current sensor has a short circuit fault.

10. A motor monitoring system, characterized in that, Includes a motor and the current sampling circuit as described in any one of claims 1 to 6.

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