Temperature acquisition method and device and medium

Abstract

The invention discloses a temperature acquisition method and device and a medium, relates to the technical field of industrial automation control, is used for realizing temperature acquisition of a frequency converter, and provides a temperature acquisition method for realizing temperature acquisition by using a standard AI terminal and a standard AO terminal of the frequency converter aiming at the problems of additional hardware cost and the like of a traditional temperature acquisition scheme. Specifically, an AO terminal and an AI terminal are connected with a thermistor, the AO terminal is used for outputting constant current, namely temperature measurement current, and the AI terminal is used for collecting terminal voltage of the thermistor, so that the value of the thermistor is calculated, the value of the thermistor is converted into an actual temperature value, and temperature collection is achieved. According to the frequency converter temperature acquisition realized based on the method, the temperature acquisition can be realized only by using the standard AI terminal, the standard AO terminal and the thermistor sensor of the frequency converter. The frequency converter does not need to increase any hardware cost, and the product competitiveness is improved.

Description

Technical Field

[0001] The present application relates to the field of industrial automation control, and in particular to a temperature acquisition method, device and medium. Background Art

[0002] In industrial automation control scenarios, the inverter requires an external temperature sensor to collect temperature data. Thermistors have the characteristic that their resistance changes with temperature, so temperature information can be indirectly obtained by measuring the resistance of thermistors. There are two main common solutions for measuring the resistance of thermistors. One is to give a constant voltage source and calculate the resistance value by measuring the voltage drop of the thermistor. The other is to give a constant current source and calculate the resistance value by measuring the voltage drop of the thermistor.

[0003] Since the inverter has its own voltage source, the current inverter temperature acquisition design generally adopts a given constant voltage source, which can save the cost of setting up a constant voltage source. However, this solution still requires the deployment of a voltage divider circuit and a voltage sampling circuit, which will incur additional costs and needs further improvement.

[0004] Therefore, technicians in this field are in urgent need of a temperature acquisition method to solve the problem that the acquisition of temperature by the frequency converter requires the additional configuration of an acquisition circuit, which incurs additional costs. Summary of the invention

[0005] The purpose of this application is to provide a temperature acquisition method, device and medium to reduce the additional cost required by the inverter when implementing temperature acquisition.

[0006] In order to solve the above technical problems, the present application provides a temperature acquisition method, which is applied to a frequency converter, wherein the frequency converter includes an analog input terminal and an analog output terminal, wherein the analog input terminal and the analog output terminal are connected to one end of a thermistor, and the other end of the thermistor is grounded. The method includes:

[0007] Control the analog output terminal to output temperature measurement current;

[0008] Measure the terminal voltage of the thermistor through the analog input terminal;

[0009] The actual temperature value is determined based on the current value of the temperature measuring current and the terminal voltage.

[0010] In a possible embodiment, the amplitude of the temperature measurement current is less than the upper amplitude limit value;

[0011] The upper limit of the amplitude is determined based on the maximum allowable current value of the thermistor and the range of the analog input terminal.

[0012] In a possible embodiment, the upper limit of the amplitude satisfies:

[0013] The upper limit of the amplitude is less than the maximum allowable current value of the thermistor;

[0014] The product of the amplitude upper limit and the maximum resistance of the thermistor is less than the range of the analog input terminal.

[0015] In a possible embodiment, the amplitude of the temperature measurement current is greater than the lower amplitude limit;

[0016] The lower limit of the amplitude is determined based on the output current accuracy of the analog output terminal and the sampling accuracy of the analog input terminal.

[0017] In a possible embodiment, the lower limit of the amplitude satisfies:

[0018] The product of the amplitude lower limit and the thermistor's resistance temperature change rate is greater than the sampling accuracy of the analog input terminal;

[0019] The lower limit of the amplitude is greater than the output current accuracy of the analog output terminal.

[0020] In a possible embodiment, outputting the temperature measurement current through the analog output terminal includes:

[0021] Output temperature measurement current in the form of PWM signal;

[0022] The equivalent current value of the PWM signal is equal to the current value of the recommended working current of the thermistor.

[0023] In a possible embodiment, the duty cycle of the PWM signal satisfies:

[0024] The heat generated by the temperature measuring current per unit time is equal to the heat generated by the recommended working current per unit time.

[0025] In a possible embodiment, the period of the PWM signal satisfies:

[0026] Determine the output duration of the temperature measurement current in one cycle based on the duty cycle and period of the PWM signal;

[0027] The output duration is greater than the product of the filter time constant of the analog output terminal and the preset multiple.

[0028] In order to solve the above technical problems, the present application also provides a temperature collection device, comprising:

[0029] Memory for storing computer programs;

[0030] The processor is used to implement the steps of the temperature acquisition method described above when executing a computer program.

[0031] In order to solve the above technical problems, the present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the temperature acquisition method described above are implemented.

[0032] The present application provides a temperature acquisition method, which uses the analog input (AI) terminal and the analog output (AO) terminal generally provided by the inverter to realize temperature acquisition. Specifically, the AO terminal can be selected to work in the mode of outputting constant voltage or outputting constant current. This method connects the AO terminal and the AI ​​terminal to the thermistor, and uses the AO terminal to output constant current, that is, output temperature measurement current, and collects the terminal voltage of the thermistor by the AI ​​terminal, thereby calculating the thermistor value, and converting the thermistor value into an actual temperature value to realize temperature acquisition. It can be seen from the above that the inverter temperature acquisition based on this method does not require a constant voltage source or a constant current source and any acquisition circuit including a voltage divider circuit and a voltage acquisition circuit. Temperature acquisition can be realized by only using the AI ​​terminal, AO terminal and thermistor sensor provided by the inverter. This makes it possible to increase the inverter without any hardware cost, and is conducive to controlling the circuit volume, realizing the miniaturization of the temperature acquisition circuit, and improving the competitiveness of the product in terms of cost and volume.

[0033] The temperature collection device and computer-readable storage medium provided in the present application correspond to the above method and have the same effects as above. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 It is a schematic diagram of measuring resistance value with a given constant voltage source;

[0036] Figure 2 It is a schematic diagram of measuring resistance value with a given constant current source;

[0037] Figure 3 A wiring diagram of a constant current temperature measurement circuit provided by the present invention;

[0038] Figure 4 A flow chart of a temperature collection method provided by the present invention;

[0039] Figure 5 A current measurement timing diagram provided by the present invention;

[0040] Figure 6 A hardware structure diagram of a constant current temperature measurement circuit provided by the present invention;

[0041] Figure 7 A flow chart of another temperature collection method provided by the present invention;

[0042] Figure 8 This is a structural diagram of a temperature collection device provided by the present invention. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0044] The core of this application is to provide a temperature collection method, device and medium.

[0045] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0046] Thermistors have the property that their resistance changes with temperature, so temperature information can be indirectly obtained by measuring the resistance of thermistors, which can be implemented as a temperature sensor. Currently, there are two main solutions for measuring the resistance of thermistors:

[0047] 1. Given a constant voltage source, measure the thermistor voltage divider;

[0048] like Figure 1 As shown in the figure, by giving a constant voltage source and measuring the divided voltage on the thermistor, the resistance value of the thermistor is calculated based on Kirchhoff's voltage law.

[0049] 2. Measure the voltage drop of thermistor with a given constant current source;

[0050] like Figure 2 As shown, by giving a constant current source and then using the voltage drop caused by the current passing through the thermistor, the resistance value of the thermistor is calculated based on Ohm's law.

[0051] In the application field of using an external thermistor to collect temperature data, since the internal hardware of the inverter has its own voltage sources such as 24V, 15V, 5V, and 3.3V, the above solution 1 is often used to design the temperature acquisition circuit of the inverter. When the above solution 1 is deployed in the inverter, there is no need to set up an additional constant voltage source / constant current source, which is conducive to reducing hardware costs.

[0052] However, even if the above solution 1 is used as the temperature acquisition design of the inverter, it is still necessary to deploy an additional voltage divider circuit (i.e. Figure 1The resistor R1 in the circuit and the voltage acquisition circuit are used to measure the voltage division of the thermistor. Therefore, it still brings additional hardware cost, which is unacceptable for the inverter positioned as an economical inverter and will reduce the product competitiveness of the inverter.

[0053] To solve the above problems, the present application provides a temperature acquisition method, which is applied to the inverter 10. Figure 3 As shown, the inverter includes an analog input (AI) terminal 11 and an analog output (AO) terminal 12. It should be noted that the AI ​​terminal and the AO terminal are connected to one end of the thermistor 20, and the other end of the thermistor 20 is grounded to realize the temperature acquisition of the inverter. The acquisition method is as follows Figure 4 As shown, including:

[0054] S11: Control the analog output terminal to output temperature measurement current.

[0055] S12: Measure the terminal voltage of the thermistor through the analog input terminal.

[0056] S13: Determine the actual temperature value according to the current value of the temperature measuring current and the terminal voltage.

[0057] From the above, it can be seen that the AI ​​terminal and the AO terminal are standard configurations of the inverter. The AI ​​terminal supports voltage input to collect voltage values, and the AO terminal can work in constant voltage or constant current mode to output a constant voltage signal or current signal.

[0058] Based on this feature, this method uses the AI ​​terminal, AO terminal and thermistor of the inverter to form a constant current temperature acquisition circuit to realize the temperature acquisition function. Among them, the AO terminal works in the constant current mode, and the output current value i of the temperature measurement current with a constant current value; the temperature measurement current generates a voltage drop after passing through the thermistor, and the voltage drop can be obtained by measuring the terminal voltage u of the thermistor through the AI ​​terminal; then based on Ohm's law The actual resistance value R of the thermistor can be determined L ; Finally, the actual resistance value R L Converted to temperature value. That is, this solution is equivalent to the above Figure 2 The resistance value measurement scheme 2 shown in the figure measures the resistance value by measuring the voltage drop of the thermistor through a constant current source.

[0059] It is not difficult to see from the above that this method uses the standard AI terminal and AO terminal of the inverter to replace the constant current source and the corresponding acquisition circuit. That is, the inverter temperature acquisition based on this method only requires a thermistor, without the need for a constant current source / constant voltage source and any acquisition circuit. Therefore, the temperature acquisition based on this method does not require any additional hardware circuits except the necessary thermistor. Compared with the above-mentioned solution 1, it has obvious advantages in circuit volume and cost, and can further improve the competitiveness of the product in terms of cost and volume.

[0060] On the other hand, since different types of sensors have different resistance ranges corresponding to their temperature measurement ranges, if a fixed-amplitude current is used for temperature measurement, the sensor may be damaged due to excessive current, or the terminal voltage generated due to too small a current may be too small to meet the sampling accuracy of the AI ​​terminal. Therefore, this embodiment also provides a possible implementation plan for the configuration of the temperature measurement current:

[0061] The amplitude of the temperature measurement current is less than the upper amplitude limit.

[0062] The upper limit of the amplitude is determined based on the maximum allowable current value of the thermistor and the range of the analog input terminal.

[0063] First of all, it should be noted that in order to ensure the safety of the constant current temperature measurement circuit, the amplitude of the temperature measurement current should not exceed the maximum current value I allowed by the thermistor. nmax . In addition, to ensure accurate measurement results, the terminal voltage generated by the temperature measurement current on the thermistor should not exceed the range of the AI ​​terminal. Therefore, based on the above two conditions, it can be used as a limit on the upper limit of the temperature measurement current amplitude. That is, when the upper limit of the amplitude of the temperature measurement current is limited based on the implementation scheme provided in this embodiment, the safety of the constant current temperature measurement circuit can be reliably guaranteed, and the problem that the resistance value of the thermistor cannot be accurately measured due to the terminal voltage exceeding the range of the AI ​​terminal can be avoided.

[0064] Furthermore, regarding how to determine the upper limit of the amplitude in the previous embodiment, this embodiment also provides a further implementation scheme, and the above-mentioned upper limit of the amplitude must meet the following two conditions:

[0065] A1: The upper limit of the amplitude is less than the maximum allowable current value of the thermistor.

[0066] A2: The product of the amplitude upper limit and the maximum resistance of the thermistor is less than the range of the analog input terminal.

[0067] Specifically, the above two conditions A1 and A2 are expressed by formulas as follows:

[0068] (1);

[0069] In the formula, I maxIndicates the upper limit of the amplitude; I nmax Indicates the maximum current value allowed by the thermistor; R max Indicates the maximum resistance of the thermistor; V r Indicates the range of the AI ​​terminal. In a possible embodiment, V r It can be 10V.

[0070] Based on the two constraints in the above formula (1), any value that meets the requirements of formula (1) can be taken as the final amplitude upper limit value I max After that, when the temperature measurement current is output through the AO terminal, the amplitude of the temperature measurement current must be less than the upper limit value I max . To ensure the safety of the constant current temperature measurement circuit and avoid inaccurate measurement caused by exceeding the range.

[0071] Similarly, in addition to limiting the upper limit of the temperature measurement current amplitude in the above embodiment, this embodiment also provides a possible solution for limiting the lower limit of the temperature measurement current amplitude:

[0072] The amplitude of the temperature measurement current is greater than the lower amplitude limit.

[0073] The lower limit of the amplitude is determined based on the output current accuracy of the analog output terminal and the sampling accuracy of the analog input terminal.

[0074] It should be noted that, in theory, the amplitude of the temperature measurement current should be as large as possible. This makes the terminal voltage of the thermistor large enough to meet the sampling accuracy requirements of the AI ​​terminal and obtain accurate voltage sampling results. Therefore, in order to ensure the accuracy of the measurement, this embodiment limits the lower limit of the temperature measurement current amplitude, and determines the lower limit of the temperature measurement current amplitude based on the output current accuracy of the AO terminal and the sampling accuracy of the analog input terminal. Then, when the temperature measurement current is output, it is ensured that its amplitude is not too small to affect the measurement accuracy.

[0075] Furthermore, this embodiment provides a further implementation scheme for determining the lower limit of the amplitude in the previous embodiment. The above lower limit of the amplitude should meet the following two conditions:

[0076] B1: The product of the amplitude lower limit and the resistance temperature change rate of the thermistor is greater than the sampling accuracy of the analog input terminal.

[0077] B2: The lower limit of the amplitude is greater than the output current accuracy of the analog output terminal.

[0078] Specifically, the above two conditions B1 and B2 are expressed by formulas as follows:

[0079] (2);

[0080] In the formula, Imin Indicates the lower limit of the amplitude; a indicates the resistance temperature change rate converted from the thermistor temperature curve, in Ω / ℃; b indicates the voltage sampling accuracy of the AI ​​terminal, in mV; c indicates the output current accuracy of the AO terminal, in mV.

[0081] Similar to the above embodiment, any value that satisfies the restriction condition of formula (2) can be selected as the amplitude lower limit value I min When the temperature measurement current is output through the AO terminal, the amplitude of the temperature measurement current is guaranteed to be greater than the lower limit value I min , thus ensuring the accuracy of the measurement results.

[0082] It should also be noted that the limiting schemes for the upper and lower limits of the temperature measurement current amplitude in the above embodiments can be implemented independently or together, and this embodiment does not limit this. When the upper and lower limits of the amplitude jointly limit the amplitude of the temperature measurement current, the selection range of the temperature measurement current amplitude I can be determined, that is, The temperature measurement current amplitude selected within this range can simultaneously meet the effects brought about by the above two embodiments, that is, ensure the safety of the constant current temperature measurement circuit and ensure the accuracy of the measurement result.

[0083] However, it should be noted that in some application scenarios, there may be The situation where both conditions cannot be met at the same time. In this case, priority should be given to , to ensure the safety of the circuit.

[0084] On the other hand, in addition to the further embodiments for the temperature measurement current amplitude provided in the above embodiments, this embodiment also provides possible implementation plans for other aspects of the configuration of the temperature measurement current. The above step S11 is specifically:

[0085] The temperature measurement current is output in the form of PWM signal.

[0086] The equivalent current value of the PWM signal is equal to the current value of the recommended working current of the thermistor.

[0087] From the above, it can be seen that the temperature acquisition method provided in this application is to replace the constant voltage source / constant current source and the corresponding acquisition circuit through the AI ​​and AO terminals of the frequency converter as standard, so as to achieve the purpose of temperature acquisition without the need for additional hardware circuits. However, since the rated operating current of the thermistor is usually very small, for example, taking the platinum resistance temperature sensor as an example, the recommended operating currents for each subdivision type are commonly 1mA, 0.5mA, 0.3mA and smaller specifications. The lower limit value of the amplitude of the temperature measurement current determined based on the above embodiment may be greater than the recommended operating current value of the thermistor, which will affect the measurement accuracy of the thermistor.

[0088] Based on this, this embodiment provides a further implementation scheme for the output form of the temperature measurement current, that is, outputting the temperature measurement current in the form of a pulse width modulation (PWM) signal. At this time, the timing of the temperature measurement current is as follows: Figure 5 As shown. That is, the temperature measurement current is continuously output for a period of time (dT, where d is the duty cycle of the PWM signal) in a PWM cycle (T). After completing the sampling of the thermistor terminal voltage, the temperature measurement current output is turned off and maintained for a period of time (T-dT), which is a PWM cycle. By outputting the temperature measurement current in the form of a PWM signal, by selecting a suitable PWM cycle and duty cycle, the average equivalent current value of the PWM signal can be kept consistent with the recommended operating current value of the thermistor, thereby solving the problem of the temperature measurement current amplitude exceeding the recommended operating current value of the thermistor affecting the measurement accuracy, and further improving the accuracy of temperature acquisition.

[0089] It can be seen from the previous embodiment that by selecting a suitable period and duty cycle, the equivalent current value of the PWM signal can be made equal to the recommended operating current value of the thermistor. The selection of the PWM signal period and duty cycle is the key to the implementation of the previous embodiment. Regarding how to select the duty cycle of the PWM signal, this embodiment provides a possible implementation scheme, and the duty cycle of the PWM signal satisfies:

[0090] The heat generated by the temperature measuring current per unit time is equal to the heat generated by the recommended working current per unit time.

[0091] As can be seen from the previous embodiment, the primary purpose of outputting the temperature measurement current in the form of PWM is to make the average equivalent current value of the temperature measurement current consistent with the recommended working current value of the thermistor. The duty cycle of the PWM signal should also be determined based on this purpose.

[0092] Specifically, the reason why the temperature measurement current amplitude is greater than the recommended working current value of the thermistor will affect the measurement accuracy is that the thermistor has a self-heating effect. That is, when the temperature measurement current flows through the thermistor R, the Joule effect will make the thermistor's own temperature higher than the measured temperature value, thereby causing measurement errors. The thermistor has fully considered the self-heating effect during design and calibrated the recommended working current value I n Therefore, in essence, this embodiment is based on Joule's law to obtain a duty cycle d so that the heat generated by the temperature measuring current I per unit time (such as period T) is equal to the recommended working current I n The heat generated per unit time is equal, thus avoiding the temperature measurement accuracy affected by the self-heating effect of the thermistor, and further ensuring the accuracy of temperature acquisition.

[0093] The duty cycle expression based on Joule's law is as follows:

[0094] (3);

[0095] On the other hand, for the selection of the PWM signal period, this embodiment also provides a possible implementation scheme, where the PWM signal period satisfies:

[0096] The output duration of the temperature measurement current in one cycle is determined based on the duty cycle and period of the PWM signal.

[0097] The output duration is greater than the product of the filter time constant of the analog output terminal and the preset multiple.

[0098] In practical applications, since there is a low-pass filter in the inverter's AO terminal current output circuit, the temperature measurement current cycle should be configured so that the temperature measurement current reaches a steady state within the time when the output is turned on to avoid errors. Assume that the filter time constant of the constant current temperature measurement circuit is , then the temperature measurement current duration generally needs to be at least , that is, dT needs to be greater than Since the duty cycle value d obtained in the above embodiment is generally small, in order to enable the temperature measurement current to reach a steady state, the period of the PWM signal needs to be longer. The recommended period is selected to be in the second level, such as 1s, 2s, etc. The actual duty cycle d and the filtering time constant of the constant current temperature measurement circuit can be used. The actual value depends on the

[0099] This embodiment limits the period of the temperature measuring current, and ensures that the output duration of the temperature measuring current meets certain requirements based on the duty cycle determined in the above embodiment, thereby ensuring that the output of the temperature measuring current reaches a steady state, avoiding errors, and further ensuring the accuracy of temperature acquisition.

[0100] On the other hand, in order to further illustrate the temperature acquisition method provided by the above embodiment, this embodiment provides a possible specific implementation plan in combination with an example. A PT100 type platinum resistor is used as a thermistor (i.e., a temperature sensor), and a Figure 6 Taking the inverter shown in the figure as an example, the temperature of the inverter is collected through the inverter AI terminal, AO terminal and PT100 platinum resistor.

[0101] 1. Inverter specifications:

[0102] AI terminal voltage sampling accuracy: 2.5mV;

[0103] AO terminal current output accuracy: 0.2mA.

[0104] 2. PT100 platinum resistor specifications:

[0105] Recommended operating current: 1mA;

[0106] Maximum allowable current: 10mA;

[0107] Resistance temperature change rate: 0.385Ω / ℃;

[0108] The maximum resistance value of the required temperature measurement range is 175.86Ω.

[0109] Based on the above parameters, the overall process of this method is as follows Figure 7 As shown:

[0110] Step 1-Select the temperature measurement current amplitude: First, based on the above formula (1), determine that the upper limit of the temperature measurement current amplitude is 10mA. According to the above formula (2), determine that the lower limit of the temperature measurement current amplitude is 7mA.

[0111] Step 2-Select the temperature measurement current form: Configure the inverter, select to output the temperature measurement current in PWM form, and collect the terminal voltage of the thermistor when outputting the temperature measurement current to calculate the resistance value and estimate the temperature.

[0112] Step 3-Select the duty cycle of the temperature measurement current: Based on the above formula (3), calculate the duty cycle of the temperature measurement current: .

[0113] Step 4-Select the temperature measurement current cycle: Select the temperature measurement current cycle as 2s, that is, the temperature measurement current output time is 40.8ms every 2s to meet the requirement that dT is greater than needs.

[0114] Step 5-Complete hardware terminal wiring: Based on Figure 3 The circuit shown completes the wiring between the inverter and the thermistor.

[0115] Step 6 - Output temperature measurement current and complete voltage sampling: within 40.8ms at the beginning of 2s, the inverter AO terminal outputs a temperature measurement current of 7mA; before turning off the temperature measurement current, the AI ​​terminal completes voltage sampling (such as completing voltage sampling before the remaining 5ms of the output temperature measurement current duration), and finally calculates the resistance value and estimates the temperature according to the temperature curve, and turns off the temperature measurement current.

[0116] Step 7-Repeat the temperature measurement data collection: Repeat the above step 6 to achieve multi-cycle temperature collection.

[0117] And during the temperature measurement process, if the hardware parameters such as thermistor and inverter change, the corresponding specification parameters will be updated before the next temperature measurement process starts. From the next temperature measurement process, the corresponding temperature measurement process will be carried out with the new specification parameters.

[0118] Figure 8 A structural diagram of a temperature acquisition device provided in another embodiment of the present application is shown as follows: Figure 8As shown, a temperature acquisition device includes: a memory 30 for storing a computer program;

[0119] The processor 31 is used to implement the steps of a temperature collection method in the above embodiment when executing a computer program.

[0120] The temperature collection device provided in this embodiment may include but is not limited to a mobile terminal, a personal computer, a workstation, etc.

[0121] Among them, the processor 31 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 31 can be implemented in at least one hardware form of a digital signal processor (DSP), a field-programmable gate array (FPGA), and a programmable logic array (PLA). The processor 31 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the awake state, also known as a central processing unit (CPU); the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the processor 31 may be integrated with a graphics processing unit (GPU), which is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 31 may also include an artificial intelligence (AI) processor, which is used to process computing operations related to machine learning.

[0122] The memory 30 may include one or more computer-readable storage media, which may be non-transitory. The memory 30 may also include a high-speed random access memory, and a non-volatile memory, such as one or more disk storage devices, flash memory storage devices. In this embodiment, the memory 30 is at least used to store the following computer program 301, wherein, after the computer program is loaded and executed by the processor 31, it can implement the relevant steps of a temperature acquisition method disclosed in any of the aforementioned embodiments. In addition, the resources stored in the memory 30 may also include an operating system 302 and data 303, etc., and the storage method may be temporary storage or permanent storage. Among them, the operating system 302 may include Windows, Unix, Linux, etc. Data 303 may include, but is not limited to, a temperature acquisition method, etc.

[0123] In some embodiments, a temperature collection device may further include a display screen 32 , an input / output interface 33 , a communication interface 34 , a power supply 35 , and a communication bus 36 .

[0124] Those skilled in the art will understand that Figure 8 The structure shown in the figure does not constitute a limitation on a temperature collection device, and may include more or fewer components than those shown in the figure.

[0125] A temperature acquisition device provided in an embodiment of the present application includes a memory and a processor. When the processor executes a program stored in the memory, it can implement the following method: a temperature acquisition method.

[0126] Finally, the present application also provides an embodiment corresponding to a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps recorded in the above method embodiment are implemented.

[0127] It is understandable that if the method in the above embodiment is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk and other media that can store program code.

[0128] The above is a detailed introduction to a temperature acquisition method, device and medium provided by the present application. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the present application.

[0129] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

Claims

1. A temperature acquisition method, applied to a frequency converter, wherein the frequency converter comprises an analog input terminal and an analog output terminal, characterized in that: The analog input terminal and the analog output terminal are connected to one end of a thermistor, and the other end of the thermistor is grounded. The method includes: Control the analog output terminal to output temperature measurement current; Measuring the terminal voltage of the thermistor through the analog input terminal; The actual temperature value is determined according to the current value of the temperature measuring current and the terminal voltage.

2. The temperature acquisition method according to claim 1, characterized in that: The amplitude of the temperature measurement current is less than the upper limit of the amplitude; The amplitude upper limit is determined based on the maximum allowable current value of the thermistor and the range of the analog input terminal.

3. The temperature acquisition method according to claim 2, characterized in that: The amplitude upper limit value satisfies: The amplitude upper limit value is less than the maximum allowable current value of the thermistor; The product of the amplitude upper limit value and the maximum resistance value of the thermistor is less than the measuring range of the analog input terminal.

4. The temperature acquisition method according to claim 2, characterized in that: The amplitude of the temperature measuring current is greater than the lower limit of the amplitude; The amplitude lower limit is determined based on the output current accuracy of the analog output terminal and the sampling accuracy of the analog input terminal.

5. The temperature acquisition method according to claim 4, characterized in that: The lower limit of the amplitude satisfies: The product of the amplitude lower limit and the resistance temperature change rate of the thermistor is greater than the sampling accuracy of the analog input terminal; The amplitude lower limit value is greater than the output current accuracy of the analog output terminal.

6. The temperature acquisition method according to any one of claims 1 to 5, characterized in that: Outputting the temperature measurement current through the analog output terminal includes: Outputting the temperature measuring current in the form of a PWM signal; Wherein, the equivalent current value of the PWM signal is equal to the current value of the recommended working current of the thermistor.

7. The temperature collection method according to claim 6, characterized in that: The duty cycle of the PWM signal satisfies: The heat generated by the temperature measuring current per unit time is equal to the heat generated by the recommended working current per unit time.

8. The temperature collection method according to claim 7, characterized in that: The period of the PWM signal satisfies: Determine the output duration of the temperature measurement current in one cycle based on the duty cycle and period of the PWM signal; The output duration is greater than the product of the filter time constant of the analog output terminal and a preset multiple.

9. A temperature collection device, characterized in that: include: Memory for storing computer programs; A processor, configured to implement the steps of the temperature acquisition method according to any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the temperature acquisition method according to any one of claims 1 to 7 are implemented.

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