An isolated grid voltage sampling device with temperature compensation and a sampling method

Abstract

The present invention provides an isolated grid voltage sampling device with temperature compensation and a sampling method. The isolated grid voltage sampling device with temperature compensation includes: a voltage dividing unit for receiving the voltage of the input grid and dividing it; a temperature compensation unit connected to the voltage dividing unit for performing temperature compensation on the divided voltage signal; an isolation unit connected to the temperature compensation unit for electrically isolating the temperature-compensated voltage signal through a non-linear optocoupler; and a signal processing unit connected to the isolation unit for amplifying and filtering the isolated voltage signal to achieve sampling of the power supply grid. The present invention realizes the sampling of the grid voltage based on a non-linear optocoupler and compensating its temperature drift, which not only meets the accuracy requirements of voltage sampling but also reduces the cost.

Description

Technical Field

[0001] The present invention belongs to the field of power grid voltage acquisition, and relates to a sampling method for isolating power grid voltage, in particular to an isolated power grid voltage sampling device and sampling method with temperature compensation. Background Art

[0002] With the development of electronic technology, the sampling of electrical parameters has wide applications in scientific research and engineering practice, and higher requirements are put forward for the accuracy and stability of sampling. The sampling of circuit voltage occupies an important position in the sampling of electrical parameters, and circuit voltage is also one of the important data for monitoring the operation of the circuit. At the same time, analog electronic technology plays a crucial role in the scientific and technological field. Analog circuit design is required in communication engineering, space science, etc., and the anti-interference ability of analog circuits is higher than that of digital circuits, and there are no problems such as the need for reset due to the program running wild in digital circuits.

[0003] In the industrial application field, each product has its own nominal rated voltage. The so-called rated voltage is the normal voltage specified by the power system and electrical equipment, and is related to some operating characteristics of the power system and electrical equipment. The actual operating voltage at each point of the power system is allowed to fluctuate up and down within a certain range, which is called voltage fluctuation. Voltage fluctuation refers to the rapid change of the effective value of the power grid voltage, that is, the root mean square value. The voltage fluctuation value is expressed as the percentage of the difference between the maximum and minimum root mean square values of the voltage at the user's common power supply point adjacent in time to the rated voltage of the power grid; the frequency of voltage fluctuation is expressed by the number of voltage fluctuations per unit time. Within this allowable deviation range, various electrical equipment and the power system itself can still operate normally. Due to the non-linear, impact and unbalanced power consumption characteristics of some loads in the power supply system, many power quality problems are caused, and voltage fluctuation and flicker are among them. Voltage fluctuation will affect the normal operation of sensitive loads and super-sensitive loads, and in severe cases, it will also affect production or cause immeasurable losses. This requires precise sampling of the power grid voltage frequently to ensure the stability and reliability of products such as drivers under various harsh power grid conditions.

[0004] At present, there are mainly two common isolated power grid voltage sampling circuits: one is the high-precision isolated sampling based on linear optocouplers, but this method has a high cost; another common method is to calculate through the bus voltage, but the accuracy of this method is difficult to meet the actual application requirements.

[0005] Therefore, how to provide a voltage sampling method with low cost and meeting the actual application requirements has actually become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0006] In view of the above-mentioned disadvantages of the prior art, the object of the present invention is to provide an isolated grid voltage sampling device with temperature compensation and a sampling method, which are used to solve the problem that the prior art cannot provide a voltage sampling method with low cost and meeting the actual application requirements.

[0007] To achieve the above object and other related objects, on the one hand, the present invention provides an isolated grid voltage sampling device with temperature compensation. The isolated grid voltage sampling device with temperature compensation includes: a voltage dividing unit, which is used to receive the voltage of the input grid and divide the voltage; a temperature compensation unit, connected to the voltage dividing unit, which is used to perform temperature compensation on the voltage signal after voltage division; an isolation unit, connected to the temperature compensation unit, which is used to electrically isolate the voltage signal after temperature compensation through a non-linear optocoupler; and a signal processing unit, connected to the isolation unit, which is used to amplify and filter the isolated voltage signal to realize the sampling of the power grid voltage.

[0008] In an embodiment of the present invention, the voltage dividing unit includes a first voltage dividing end, a second voltage dividing end and a rectifying device; a plurality of series-connected voltage dividing resistors are respectively arranged at the first voltage dividing end and the second voltage dividing end.

[0009] In an embodiment of the present invention, the first voltage dividing end is provided with a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor connected in series in sequence; the second voltage dividing end is provided with a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor and a tenth resistor connected in series in sequence; the rectifying device is used to perform half-wave rectification on the voltage signal after voltage division and includes a power diode, one end of the power diode is connected to the fifth resistor, and the other end is connected to the tenth resistor.

[0010] In an embodiment of the present invention, the live wire of the grid power supply is connected to one end of the first resistor, the other end of the first resistor is connected to one end of the second resistor, the other end of the second resistor is connected to one end of the third resistor, the other end of the third resistor is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to one end of the fifth resistor, and the other end of the fifth resistor is connected to the cathode of the power diode; the neutral wire of the grid power supply is connected to one end of the sixth resistor, the other end of the sixth resistor is connected to one end of the seventh resistor, the other end of the seventh resistor is connected to one end of the eighth resistor, the other end of the eighth resistor is connected to one end of the ninth resistor, the other end of the ninth resistor is connected to one end of the tenth resistor, and the other end of the tenth resistor is connected to the anode of the power diode.

[0011] In an embodiment of the present invention, the temperature compensation unit includes: an eleventh resistor and a zener diode; one end of the eleventh resistor is respectively connected to the cathode of the power diode and the cathode of the zener diode, and the other end is connected to the anode of the power diode.

[0012] In an embodiment of the present invention, the isolation unit includes a non-linear optocoupler. The first pin of the non-linear optocoupler is connected to the anode of the zener diode, and the second pin of the non-linear optocoupler is connected to the other end of the eleventh resistor.

[0013] In an embodiment of the present invention, the signal processing unit includes: a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a triode, and a capacitor; one end of the twelfth resistor is connected to a DC power supply, and the other end is respectively connected to the fourth pin of the non-linear optocoupler, one end of the thirteenth resistor, and the collector of the triode; the other end of the thirteenth resistor is connected to one end of the capacitor to serve as a voltage sampling signal terminal, and the other end of the capacitor is connected to the ground of the DC power supply; one end of the fourteenth resistor is respectively connected to the third pin of the non-linear optocoupler and the base of the triode, and the other end of the fourteenth resistor and the emitter of the triode are both connected to the ground of the DC power supply.

[0014] On the other hand, the present invention provides a method for isolating and sampling grid voltage with temperature compensation. The method for isolating and sampling grid voltage with temperature compensation includes: receiving the voltage of the input grid through a voltage dividing unit and dividing the voltage; performing temperature compensation on the voltage signal after voltage division through a temperature compensation unit; using an isolation unit to electrically isolate the voltage signal after temperature compensation through a non-linear optocoupler; performing amplification and filtering processing on the voltage signal after isolation through a signal processing unit to achieve sampling of the grid voltage of the power supply grid.

[0015] In an embodiment of the present invention, the temperature compensation unit includes: an eleventh resistor and a zener diode. The step of performing temperature compensation on the voltage signal after voltage division through the temperature compensation unit includes: determining a non-linear optocoupler and a zener diode according to the sampled voltage requirement; calculating the temperature drift coefficient according to the voltage performance of the non-linear optocoupler in the isolation unit at different temperatures and the voltage performance of the zener diode at different temperatures; determining the eleventh resistor that meets the temperature drift coefficient.

[0016] In an embodiment of the present invention, the non-linear optocoupler and the voltage stabilizing diode operate normally within a certain temperature range. The lowest temperature and the highest temperature during the operation of the non-linear optocoupler and the voltage stabilizing diode are determined by the certain temperature range, and the same lowest temperature and the same highest temperature are selected for the non-linear optocoupler and the voltage stabilizing diode. The steps of calculating the temperature drift coefficient according to the voltage performance of the non-linear optocoupler at different temperatures and the voltage performance of the voltage stabilizing diode at different temperatures in the isolation unit include: summing the forward conduction voltage of the non-linear optocoupler at the lowest temperature and the stable voltage of the voltage stabilizing diode at the lowest temperature to determine a minimum voltage value; summing the forward conduction voltage of the non-linear optocoupler at the highest temperature and the stable voltage of the voltage stabilizing diode at the highest temperature to determine a maximum voltage value; summing the forward conduction voltage nominal value of the non-linear optocoupler in the specification and the stable voltage nominal value of the voltage stabilizing diode in the specification to determine a normal voltage value; usually, the nominal values in the component specifications are measured at 25°C; calculating the temperature drift coefficient according to the formula: temperature drift coefficient = ((maximum voltage value - minimum voltage value) * 10^6) / ((highest temperature - lowest temperature) * normal voltage value).

[0017] As described above, for the isolation grid voltage sampling device and sampling method with temperature compensation of the present invention, the voltage connected to the grid is divided by a voltage dividing resistor and half-wave rectified; based on the opto-isolation characteristic of the non-linear optocoupler, the primary side and the secondary side are isolated to achieve the effect of isolating the grid; the temperature drift of the non-linear optocoupler is compensated by a positive temperature coefficient resistor and a positive temperature coefficient voltage stabilizing diode; because the opto-coupling of the non-linear optocoupler is limited by the magnitude of the current transfer ratio, the current transfer is equivalently increased significantly by the triode on the secondary side, so that the rising edge and the falling edge of the output quickly form a square wave, avoiding the formation of a trapezoidal wave. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It shows a schematic diagram of the structural connection of the isolation grid voltage sampling device with temperature compensation of the present invention in an embodiment.

[0019] Figure 2 It shows a circuit schematic diagram of the isolation grid voltage sampling device with temperature compensation of the present invention in an embodiment.

[0020] Figure 3 It shows a principle flow chart of the isolation grid voltage sampling method with temperature compensation of the present invention in an embodiment.

[0021] Figure 4 It shows a temperature compensation flow chart of the isolation grid voltage sampling method with temperature compensation of the present invention in an embodiment.

[0022] Figure 5Shown is the flowchart for calculating the temperature drift coefficient of the isolated grid voltage sampling method with temperature compensation according to an embodiment of the present invention.

[0023] Description of Component Labels

[0024] 1 Isolated Grid Voltage Sampling Device with Temperature Compensation

[0025] 11 Voltage Dividing Unit

[0026] 12 Temperature Compensation Unit

[0027] 13 Isolation Unit

[0028] 14 Signal Processing Unit

[0029] S31 - S34 Steps of the Isolated Grid Voltage Sampling Method with Temperature Compensation

[0030] S321 - S323 Steps of the Temperature Compensation Process

[0031] S322A - S322D Steps of Calculating the Temperature Drift Coefficient Detailed Embodiment

[0032] The following illustrates the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0033] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0034] For the isolated grid voltage sampling device and sampling method with temperature compensation according to the present invention, voltage sampling is performed through a non - linear optocoupler, which reduces the cost while meeting the sampling requirements. Due to the temperature drift of the non - linear optocoupler, temperature compensation is carried out through the cooperation of a positive temperature coefficient resistor and a positive temperature coefficient zener diode, which reduces the proportion of voltage fluctuations on the primary side of the non - linear optocoupler and greatly increases the voltage stability, thereby achieving isolation of the power supply grid and relatively accurate voltage sampling.

[0035] The following will describe in detail an isolated grid voltage sampling device with temperature compensation and a sampling method provided by this embodiment in conjunction with the drawings.

[0036] As Figure 1 shown, in one embodiment, the isolated grid voltage sampling device 1 with temperature compensation includes: a voltage divider unit 11, a temperature compensation unit 12, an isolation unit 13, and a signal processing unit 14.

[0037] The voltage divider unit 11 is configured to receive the voltage of the input grid and divide it.

[0038] The temperature compensation unit 12 is connected to the voltage divider unit and is used to perform temperature compensation on the divided voltage signal.

[0039] The isolation unit 13 is connected to the temperature compensation unit and is used to electrically isolate the temperature-compensated voltage signal through a non-linear optocoupler.

[0040] The signal processing unit 14 is connected to the isolation unit and is used to amplify and filter the isolated voltage signal to achieve sampling of the power grid voltage.

[0041] As Figure 2 shown, in one embodiment, the live wire end ACL and the neutral wire end ACN of the grid voltage are respectively connected to Figure 2 the circuit, and the sampling of the voltage signal V-SAMP is achieved through voltage division, half-wave rectification, temperature compensation, voltage isolation, and amplification and filtering in sequence.

[0042] In one embodiment, the voltage divider unit 11 includes a first voltage division end, a second voltage division end, and a rectifying device; multiple voltage dividing resistors connected in series are respectively provided at the first voltage division end and the second voltage division end.

[0043] Specifically, the first voltage division end is provided with a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5 connected in series in sequence.

[0044] The second voltage division end is provided with a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10 connected in series in sequence.

[0045] The rectifying device is used to perform half-wave rectification on the divided voltage signal and includes a power diode D1. One end of the power diode D1 is connected to the fifth resistor R5, and the other end is connected to the tenth resistor R10.

[0046] In one embodiment, the live wire ACL of the power grid power supply is connected to one end of the first resistor R1. The other end of the first resistor R1 is connected to one end of the second resistor R2. The other end of the second resistor R2 is connected to one end of the third resistor R3. The other end of the third resistor R3 is connected to one end of the fourth resistor R4. The other end of the fourth resistor R4 is connected to one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to the cathode of the power diode D1.

[0047] The neutral wire ACN of the power grid power supply is connected to one end of the sixth resistor R6. The other end of the sixth resistor R6 is connected to one end of the seventh resistor R7. The other end of the seventh resistor R7 is connected to one end of the eighth resistor R8. The other end of the eighth resistor R8 is connected to one end of the ninth resistor R9. The other end of the ninth resistor R9 is connected to one end of the tenth resistor R10. The other end of the tenth resistor R10 is connected to the anode of the power diode D1.

[0048] It should be noted that the connection form of the voltage dividing resistors in the voltage dividing unit 11, in addition to the connection of the ten resistors R1 - R10, other numbers of voltage dividing resistors combined with the input voltage and power for ratio matching and series connection and meeting the derating requirements are also included in the protection scope of this application.

[0049] In one embodiment, the temperature compensation unit 12 includes: the eleventh resistor R11 and the voltage stabilizing diode ZD1.

[0050] One end of the eleventh resistor R11 is respectively connected to the cathode of the power diode D1 and the cathode of the voltage stabilizing diode ZD1, and the other end is connected to the anode of the power diode D1.

[0051] In one embodiment, the isolation unit 13 includes a non - linear optocoupler PC1. The first pin of the non - linear optocoupler PC1 is connected to the anode of the voltage stabilizing diode ZD1, and the second pin of the non - linear optocoupler PC1 is connected to the other end of the eleventh resistor R11.

[0052] In one embodiment, the signal processing unit 14 includes: the twelfth resistor R12, the thirteenth resistor R13, the fourteenth resistor R14, the triode Q1 and the capacitor C1.

[0053] One end of the twelfth resistor R12 is connected to the DC power supply +5V, and the other end is respectively connected to the fourth pin of the non - linear optocoupler PC1, one end of the thirteenth resistor R13 and the collector of the triode Q1.

[0054] The other end of the thirteenth resistor R13 is connected to one end of the capacitor C1, and serves as a voltage sampling signal terminal to output V-SAMP. The other end of the capacitor C1 is connected to the ground GND of the DC power supply.

[0055] One end of the fourteenth resistor R14 is respectively connected to the third pin of the non-linear optocoupler PC1 and the base of the triode Q1. The other end of the fourteenth resistor R14 and the emitter of the triode Q1 are both connected to the ground GND of the DC power supply. After using the triode Q1, the current amplification factor increases from 1.3 - 2.6 times to 319.8 - 639.6 times. It greatly reduces the time from the primary side conduction to the secondary side saturation. At the same time, due to the large uncertainty of the CTR (Current Transfer Ratio) of the optocoupler, the triode can greatly reduce its influence.

[0056] The working process of the isolated grid voltage sampling device with temperature compensation is as follows: The voltage accessed by the grid is divided by the voltage dividing resistors. Due to the presence of the diode D1, the output voltage waveform of the voltage dividing unit is a half-wave. Based on the opto-isolation characteristic of the non-linear optocoupler PC1, the primary side and the secondary side are isolated, achieving the effect of isolating the grid. However, the non-linear optocoupler has a temperature drift phenomenon, that is, the change of semiconductor device parameters caused by temperature change is the main reason for the zero drift phenomenon. Therefore, the zero drift is also called temperature drift, abbreviated as temperature drift. To overcome the above disadvantages, a positive temperature coefficient resistor R11 and a positive temperature coefficient voltage stabilizing diode ZD1 are used to compensate for the temperature drift of the non-linear optocoupler. Because the opto-coupling of the non-linear optocoupler PC1 is limited by the magnitude of the current transfer ratio, the triode Q1 on the secondary side is used to equivalently increase the current transfer significantly, so that the rising edge and the falling edge of the output quickly form a square wave, avoiding the formation of a trapezoidal wave.

[0057] It should be noted that the isolated grid voltage sampling device with temperature compensation of the present invention can implement the isolated grid voltage sampling method with temperature compensation of the present invention. However, the implementation device of the isolated grid voltage sampling method with temperature compensation of the present invention includes but is not limited to the structure of the isolated grid voltage sampling device listed in this embodiment. Any structural deformation and replacement of the prior art made according to the principle of the present invention are included in the protection scope of the present invention.

[0058] As Figure 3 shown, in one embodiment, the isolated grid voltage sampling method with temperature compensation specifically includes the following steps:

[0059] S31, receive the voltage of the input grid through the voltage dividing unit and divide it.

[0060] S32. Perform temperature compensation on the voltage signal after voltage division through the temperature compensation unit.

[0061] S33. Isolate the voltage signal after temperature compensation through the isolation unit using a non - linear optocoupler.

[0062] S34. Amplify and filter the isolated voltage signal through the signal processing unit to achieve sampling of the power grid voltage.

[0063] Further, as Figure 4 shown, in an embodiment, the temperature compensation unit includes: an eleventh resistor and a zener diode. S32 specifically includes the following steps:

[0064] S321. Determine a non - linear optocoupler and a zener diode according to the sampled voltage requirement.

[0065] Specifically, in addition to determining a zener diode, it is necessary to consider the selection of the forward conduction voltage of the zener diode ZD1, the non - linear optocoupler PC1, and the temperature drift parameter of the eleventh resistor R11 to achieve the effect of compensating for temperature rise. The parameters of the three need to be considered together as long as the positive and negative cancel each other out.

[0066] S322. Calculate the temperature drift coefficient according to the voltage performance of the non - linear optocoupler in the isolation unit at different temperatures and the voltage performance of the zener diode at different temperatures.

[0067] As Figure 5 shown, in an embodiment, the non - linear optocoupler and the zener diode work normally within a certain temperature range. Determine the lowest temperature and the highest temperature when the non - linear optocoupler and the zener diode work from the certain temperature range, and select the same lowest temperature and the same highest temperature for the non - linear optocoupler and the zener diode. S32 specifically includes the following steps:

[0068] S322A. Sum the forward conduction voltage of the non - linear optocoupler at the lowest temperature and the stable voltage of the zener diode at the lowest temperature to determine a minimum voltage value.

[0069] Specifically, if at Tmin °C, the forward conduction voltage Vf of the non - linear optocoupler is V1min and the stable voltage Vz of the zener diode ZD1 is V2min, then Vmin = V1min + V2min.

[0070] S322B. Sum the forward conduction voltage of the non - linear optocoupler at the highest temperature and the stable voltage of the zener diode at the highest temperature to determine a maximum voltage value.

[0071] Specifically, when at Tmax °C, the forward conduction voltage Vf of the non-linear optocoupler is V1max, and the stabilization voltage Vz of the voltage stabilizing diode ZD1 is V2max, then Vmax = V1max + V2max.

[0072] S322C, sum the forward conduction voltage nominal value of the non-linear optocoupler in the specification sheet and the stabilization voltage nominal value of the voltage stabilizing diode in the specification sheet to determine a normal voltage value; the nominal value in the specification sheet is usually measured at 25 °C.

[0073] Specifically, if the nominal value of the forward conduction voltage Vf of the non-linear optocoupler is V1nom, and the nominal value of the stabilization voltage Vz of the voltage stabilizing diode ZD1 is V2nom, then Vnom = V1nom + V2nom.

[0074] S322D, calculate the temperature drift coefficient according to Temperature drift coefficient = ((Voltage maximum value - Voltage minimum value) * 10^6) / ((Highest temperature - Lowest temperature) * Normal voltage value).

[0075] Specifically, calculate the temperature drift coefficient of the eleventh resistor R11 according to Temperature drift TC = ((Vmax - Vmin) * 10^6) / ((Tmax - Tmin) * Vnom). When the temperature drift coefficient of R11 is equal to or close to the calculated TC value, temperature compensation can be achieved.

[0076] S323, determine the eleventh resistor that meets the temperature drift coefficient.

[0077] In an actual application of this embodiment, at -25 °C, the forward conduction voltage of the non-linear optocoupler is 1.3V; at 75 °C, the forward conduction voltage of the non-linear optocoupler is 0.9V, and the nominal value at normal temperature is 1.2V. The voltage drift can be calculated as (1.3V - 0.9V) / 1.2V, which is approximately 33%. After using the stabilization voltage of 12V of the voltage stabilizing diode ZD1 to boost the voltage, without considering the temperature drift of the voltage stabilizing diode ZD1 for the moment, the voltage drift of 0.4V between 1.3V and 0.9V can be calculated as ((1.3V + 12V) - (0.9V + 12V)) / (1.2V + 12V), which is approximately 3.03%.

[0078] To achieve more precise temperature compensation, the determination process of the resistor R11 with a positive temperature coefficient is as follows (considering the temperature drift of the voltage stabilizing diode ZD1):

[0079] If at -25 °C, the forward conduction voltage Vf of the non-linear optocoupler PC1 is 1.3V, and the stabilization voltage of the voltage stabilizing diode ZD1 is 12.1V, then Vmin = 1.3 + 12.1 = 13.4V.

[0080] If at 75°C, the forward conduction voltage Vf of the non-linear optocoupler PC1 is 0.9V and the stabilized voltage of the zener diode ZD1 is 12.9V, then Vmax = 0.9 + 12.9 = 13.8V.

[0081] If at room temperature, the nominal forward conduction voltage of the non-linear optocoupler PC1 is 1.2V and the stabilized voltage of the zener diode ZD1 is 12V.

[0082] Then Vnom = 1.2 + 12 = 13.2V.

[0083] According to the temperature drift calculation formula, we can get: TC = ((13.8 - 13.4) * 10^6) / ((75 - (-25)) * 13.2) = 303 ppm / °C

[0084] Therefore, when the stabilized voltage of the zener diode ZD1 is selected as 12V, R11 is selected as a positive temperature coefficient resistor with a positive temperature coefficient of 300 ppm level to achieve temperature compensation.

[0085] It should be noted that the protection scope of the isolated grid voltage sampling method with temperature compensation described in the present invention is not limited to the execution order of the steps listed in this embodiment. Any scheme realized by adding or reducing steps and replacing steps of the prior art according to the principle of the present invention is included in the protection scope of the present invention.

[0086] In summary, for the isolated grid voltage sampling device and sampling method with temperature compensation described in the present invention, the voltage connected to the grid is divided by a voltage-dividing resistor and half-wave rectified; based on the opto-isolation characteristic of the non-linear optocoupler, the primary side and the secondary side are isolated to achieve the effect of isolating the grid; the temperature drift of the non-linear optocoupler is compensated by a positive temperature coefficient resistor and a positive temperature coefficient zener diode; because the opto-coupling of the non-linear optocoupler is limited by the magnitude of the current transfer ratio, the current transfer is equivalently increased significantly through the triode on the secondary side, so that the rising edge and the falling edge of the output quickly form a square wave to avoid forming a trapezoidal wave. The present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0087] The above embodiments are only illustrative of the principles and effects of the present invention, rather than limiting the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. An isolated grid voltage sampling device with temperature compensation, characterized in that, The isolated grid voltage sampling device with temperature compensation includes: A voltage dividing unit, configured to receive the voltage of the input grid and divide the voltage. A temperature compensation unit, connected to the voltage dividing unit, configured to perform temperature compensation on the voltage signal after voltage division. An isolation unit, connected to the temperature compensation unit, configured to electrically isolate the voltage signal after temperature compensation through a non-linear optocoupler in the isolation unit. A signal processing unit, connected to the isolation unit, configured to amplify and filter the isolated voltage signal to achieve sampling of the supply grid voltage. The temperature compensation unit includes: an eleventh resistor, a zener diode. The non-linear optocoupler and the zener diode operate normally within a certain temperature range. The lowest temperature and the highest temperature when the non-linear optocoupler and the zener diode operate are determined by the certain temperature range, and the same lowest temperature and the same highest temperature are selected for the non-linear optocoupler and the zener diode. The steps of performing temperature compensation on the voltage signal after voltage division include: determining a non-linear optocoupler and a zener diode according to the sampled voltage, the working ambient temperature range, and the required sampling accuracy requirement; calculating the temperature drift coefficient according to the voltage performance of the non-linear optocoupler in the isolation unit at different temperatures and the voltage performance of the zener diode at different temperatures; determining the eleventh resistor that meets the temperature drift coefficient. Among them, the steps of calculating the temperature drift coefficient according to the voltage performance of the non-linear optocoupler in the isolation unit at different temperatures and the voltage performance of the zener diode at different temperatures include: summing the forward conduction voltage of the non-linear optocoupler at the lowest temperature and the stable voltage of the zener diode at the lowest temperature to determine a minimum voltage value; summing the forward conduction voltage of the non-linear optocoupler at the highest temperature and the stable voltage of the zener diode at the highest temperature to determine a maximum voltage value; summing the nominal forward conduction voltage of the non-linear optocoupler in the specification and the nominal stable voltage of the zener diode in the specification to determine a normal voltage value; the nominal value in the specification is measured at 25°C; calculating the temperature drift coefficient according to the formula: temperature drift coefficient = ((maximum voltage value - minimum voltage value) * 10^6) / ((highest temperature - lowest temperature) * normal voltage value).

2. The isolated grid voltage sampling device with temperature compensation according to claim 1, wherein The voltage dividing unit includes a first voltage dividing terminal, a second voltage dividing terminal, and a rectifying device; multiple series-connected voltage dividing resistors are respectively provided at the first voltage dividing terminal and the second voltage dividing terminal.

3. The isolated grid voltage sampling device with temperature compensation according to claim 2, wherein The first voltage dividing terminal is provided with a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor connected in series in sequence. The second voltage dividing terminal is provided with a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, and a tenth resistor connected in series in sequence. The rectifying device is configured to perform half-wave rectification on the voltage signal after voltage division, and includes a power diode. One end of the power diode is connected to the fifth resistor, and the other end is connected to the tenth resistor.

4. The isolated grid voltage sampling device with temperature compensation according to claim 3, wherein The live wire of the grid power supply is connected to one end of the first resistor, the other end of the first resistor is connected to one end of the second resistor, the other end of the second resistor is connected to one end of the third resistor, the other end of the third resistor is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to one end of the fifth resistor, and the other end of the fifth resistor is connected to the cathode of the power diode; The neutral wire of the grid power supply is connected to one end of the sixth resistor, the other end of the sixth resistor is connected to one end of the seventh resistor, the other end of the seventh resistor is connected to one end of the eighth resistor, the other end of the eighth resistor is connected to one end of the ninth resistor, the other end of the ninth resistor is connected to one end of the tenth resistor, and the other end of the tenth resistor is connected to the anode of the power diode.

5. The isolated grid voltage sampling device with temperature compensation according to claim 4, wherein One end of the eleventh resistor is respectively connected to the cathode of the power diode and the cathode of the zener diode, and the other end is connected to the anode of the power diode.

6. The isolated grid voltage sampling device with temperature compensation according to claim 5, wherein The first pin of the non-linear optocoupler is connected to the anode of the zener diode, and the second pin of the non-linear optocoupler is connected to the other end of the eleventh resistor.

7. The isolated grid voltage sampling device with temperature compensation according to claim 6, wherein The signal processing unit includes: a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a triode and a capacitor; One end of the twelfth resistor is connected to the DC power supply, and the other end is respectively connected to the fourth pin of the non-linear optocoupler, one end of the thirteenth resistor and the collector of the triode; The other end of the thirteenth resistor is connected to one end of the capacitor, serving as the voltage sampling signal terminal, and the other end of the capacitor is connected to the ground of the DC power supply; One end of the fourteenth resistor is respectively connected to the third pin of the non-linear optocoupler and the base of the triode, and the other end of the fourteenth resistor and the emitter of the triode are both connected to the ground of the DC power supply.

8. An isolation power grid voltage sampling method with temperature compensation, characterized in that, The isolated grid voltage sampling method with temperature compensation includes: Receiving the voltage of the input grid through the voltage dividing unit and dividing the voltage; Performing temperature compensation on the voltage signal after voltage division through the temperature compensation unit; Using the isolation unit to electrically isolate the voltage signal after temperature compensation through the non-linear optocoupler; Performing amplification and filtering processing on the isolated voltage signal through the signal processing unit to realize the sampling of the power grid voltage; The temperature compensation unit includes: an eleventh resistor, a zener diode; The nonlinear optocoupler and the voltage stabilizing diode operate normally within a certain temperature range. The lowest temperature and the highest temperature when the nonlinear optocoupler and the voltage stabilizing diode operate are determined by the certain temperature range, and the same lowest temperature and the same highest temperature are selected for the nonlinear optocoupler and the voltage stabilizing diode; The steps of temperature compensating the voltage signal after voltage division by the temperature compensation unit include: determining a nonlinear optocoupler and a voltage stabilizing diode according to the sampled voltage, the working ambient temperature range and the required sampling accuracy requirement; calculating the temperature drift coefficient according to the voltage performance of the nonlinear optocoupler in the isolation unit at different temperatures and the voltage performance of the voltage stabilizing diode at different temperatures; determining the eleventh resistor that meets the temperature drift coefficient; Among them, the steps of calculating the temperature drift coefficient according to the voltage performance of the nonlinear optocoupler in the isolation unit at different temperatures and the voltage performance of the voltage stabilizing diode at different temperatures include: summing the forward conduction voltage of the nonlinear optocoupler at the lowest temperature and the stable voltage of the voltage stabilizing diode at the lowest temperature to determine a minimum voltage value; summing the forward conduction voltage of the nonlinear optocoupler at the highest temperature and the stable voltage of the voltage stabilizing diode at the highest temperature to determine a maximum voltage value; summing the nominal forward conduction voltage of the nonlinear optocoupler in the specification and the nominal stable voltage of the voltage stabilizing diode in the specification to determine a normal voltage value; the nominal value in the specification is measured at 25 °C; calculating the temperature drift coefficient according to the temperature drift coefficient = ((maximum voltage value - minimum voltage value) * 10^6) / ((highest temperature - lowest temperature) * normal voltage value).

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