Sine voltage detection circuit and detection system

Abstract

The utility model relates to the field of voltage detection, and discloses a sinusoidal voltage detection circuit and a detection system. Comprising a controller, a first voltage division circuit, a second voltage division circuit, an operational amplifier and a biasing circuit, the biasing circuit is connected with the first voltage division circuit or the second voltage division circuit; the controller is connected with the first voltage division circuit and the second voltage division circuit; and the controller is also connected with the output end of the operational amplifier. According to the application, the bias voltage is introduced to only sample the voltage extreme value in each sine period, so that whether the sine function in the period is normal or not is judged by utilizing the characteristics of the sine signal, data in the whole period does not need to be sampled, the sampling efficiency is improved, and the sampling cost is reduced. Furthermore, the controller adjusts the resistance value of each voltage sampling circuit, so that the voltage detection circuit can detect circuits with different output voltages, and the application range is further expanded.

Description

Technical Field

[0001] The utility model relates to the field of voltage detection, in particular to a sinusoidal voltage detection circuit and a detection system. Background Art

[0002] Feedback control refers to the process of controlling the system by using the deviation between the system input information and output information. It has the ability to suppress the influence of any internal and external disturbances on the controlled quantity, has high control accuracy, and is widely used in fields such as electrical control.

[0003] In an electrical control system, the output voltage of the system is usually returned to the input end as a feedback signal of the system. Therefore, it is necessary to sample the output signal of the system through a voltage sampling circuit. Figure 1 This is a structural diagram of a car dimming glass control system. Figure 1 As shown, the voltage controller is connected to the polymer dispersed liquid crystal (PDLC) dimming glass to provide a sinusoidal voltage to the PDLC dimming glass to change the transmittance of the glass. The transmittance of the PDLC dimming glass is determined by the sinusoidal voltage. In order to ensure that the transmittance meets the user's needs, the sinusoidal voltage output by the voltage controller needs to be detected to ensure that the sinusoidal voltage received by the PDLC dimming glass is a signal corresponding to the user's needs. The sinusoidal voltage detection device currently used often needs to detect all voltage values ​​within a cycle to determine whether the voltage signal is a sinusoidal signal, which places high requirements on the accuracy and performance of the sampling equipment, resulting in an increase in the cost of the sinusoidal voltage detection device.

[0004] It can be seen that how to provide a new voltage detection circuit to reduce the equipment cost while ensuring the voltage detection accuracy is a problem that those skilled in the art need to solve urgently. Utility Model Content

[0005] The purpose of the utility model is to solve the problem that the existing voltage detection circuit needs to sample the sinusoidal voltage within the entire cycle, which leads to high sampling equipment costs. Therefore, the present application provides a sinusoidal voltage detection circuit and detection system to reduce equipment costs while ensuring voltage detection accuracy.

[0006] In order to solve the above technical problems, the present application provides a sinusoidal voltage detection circuit, comprising: a controller, a first voltage divider circuit, a second voltage divider circuit, an operational amplifier and a bias circuit; the first voltage divider circuit is arranged between the first end of the sinusoidal circuit to be measured and the inverting input end of the operational amplifier, and the second voltage divider circuit is arranged between the second end of the sinusoidal circuit to be measured and the non-inverting input end of the operational amplifier; the bias circuit is connected to the first voltage divider circuit or the second voltage divider circuit to provide a bias voltage;

[0007] The controller is connected to both the first voltage divider circuit and the second voltage divider circuit to determine the resistance values ​​of the first voltage divider circuit and the second voltage divider circuit and the bias voltage according to a corresponding relationship between a detection instruction and the resistance values ​​of the first voltage divider circuit, the second voltage divider circuit and the bias voltage;

[0008] The controller is also connected to the output terminal of the operational amplifier to obtain a voltage detection value.

[0009] In some embodiments, the first voltage divider circuit and the second voltage divider circuit both include a first resistor and a second resistor;

[0010] The first end of the first resistor is used as the first end of the voltage divider circuit and is connected to the sinusoidal circuit to be measured;

[0011] The second end of the first resistor is connected to the first end of the second resistor, and the connection point serves as a sampling point of the voltage divider circuit, and the second end of the second resistor serves as the second end of the voltage divider circuit; wherein the second resistors are adjustable resistors, and the controller is connected to the second resistors to control the ratio of the first resistor to the second resistor to be a value corresponding to a required amplification factor; the required amplification factor is a value determined according to the detection instruction.

[0012] In some embodiments, the bias circuit includes a bias power supply and a bias resistor;

[0013] A first end of the bias resistor is connected to the bias power supply, and a second end of the bias resistor is connected to a sampling point of the first voltage divider circuit or the second voltage divider circuit to provide the bias voltage.

[0014] In some embodiments, the controller is also connected to the PWM modulation signal input terminal of the sinusoidal circuit to be tested, so as to obtain the voltage detection value when the voltage extreme value signal is obtained.

[0015] In some embodiments, the second end of the third resistor is connected to the sampling end of the first voltage divider circuit to input the bias voltage.

[0016] In some embodiments, the second end of the third resistor is connected to a sampling end of the second voltage divider circuit to output the bias voltage.

[0017] In some embodiments, a display unit is also included;

[0018] The display unit is connected to the controller to obtain and display the voltage detection value.

[0019] In some embodiments, an alarm unit is further included, and the alarm unit is connected to the controller to send an alarm message when the voltage detection value does not meet a preset condition.

[0020] In some embodiments, a human-computer interaction unit is also included; the human-computer interaction unit is connected to the controller to input the detection instruction and the preset condition.

[0021] In order to solve the above technical problems, the present application also provides a sinusoidal voltage detection system, including the sinusoidal voltage detection circuit.

[0022] The present application provides a sinusoidal voltage detection circuit, including: a controller, a first voltage divider circuit, a second voltage divider circuit, an operational amplifier and a bias circuit; the first voltage divider circuit is arranged between the first end of the sinusoidal circuit to be measured and the inverting input end of the operational amplifier, and the second voltage divider circuit is arranged between the second end of the sinusoidal circuit to be measured and the non-inverting input end of the operational amplifier; the bias circuit is connected to the first voltage divider circuit or the second voltage divider circuit to provide a bias voltage; the controller is connected to both the first voltage divider circuit and the second voltage divider circuit to determine the resistance and bias voltage of the first voltage divider circuit and the second voltage divider circuit according to the corresponding relationship between the detection instruction and the resistance of the first voltage divider circuit, the resistance of the second voltage divider circuit and the bias voltage; the controller is also connected to the output end of the operational amplifier to obtain the voltage detection value. It can be seen that the technical solution provided by the present application introduces a bias voltage to sample only the maximum voltage value in each sinusoidal cycle, so as to use the characteristics of the sinusoidal signal to judge whether the sinusoidal function in the cycle is normal, without sampling the data in the entire cycle, thereby improving the sampling efficiency and reducing the sampling cost. Furthermore, the controller adjusts the resistance value of each voltage sampling circuit so that the sinusoidal voltage detection circuit can detect circuits with different output voltages, thereby further improving the application range.

[0023] In addition, the present application also provides a sinusoidal voltage detection system, including the above-mentioned sinusoidal voltage detection circuit, with the same effect as above. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present utility model, 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 utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 This is a structural diagram of a car dimming glass control system;

[0026] Figure 2 This is a common sinusoidal AC voltage waveform diagram for driving PDLC dimming glass with an effective value of 48V and a frequency of 50Hz;

[0027] Figure 3 A structural diagram of a sinusoidal voltage peak detection circuit provided in an embodiment of the present application;

[0028] Figure 4 A structural diagram of a sinusoidal voltage valley detection circuit provided in an embodiment of the present application;

[0029] Figure 5 A schematic diagram of an effective sampling interval of a sinusoidal peak voltage provided in an embodiment of the present application;

[0030] Figure 6 A structural diagram of a voltage detection system provided in an embodiment of the present application;

[0031] The reference numerals in the drawings are as follows: 1 is a controller, 2 is a first voltage divider circuit, 3 is a second voltage divider circuit, 4 is an operational amplifier, 5 is a bias circuit, and 6 is a sinusoidal voltage detection circuit. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the utility model.

[0033] like Figure 1 As shown, the controller 1 converts the battery DC power into a driving PDLC voltage; Figure 2 This is a common sinusoidal AC voltage waveform diagram for driving PDLC dimming glass with an effective value of 48V and a frequency of 50Hz, as shown in Figure 2 As shown, the output voltage is 48V / 50Hz sine (48V is the effective value); the control converts the output voltage of 48VAC into a 0~5V voltage of the sampling port of the controller 1 through a certain ratio and deviation. Figure 1 and Figure 2 It can be seen that the voltage span of the 48VAC waveform is close to 136V, while the sampling port voltage input is usually 3.3V or 5V; when the output voltage changes by 1V, such as 47VAC, the sampling port voltage changes by only about 100mV. In fact, since the sampling range of controller 1 will make some reservations for the voltage of the acquisition object, the actual application sampling port voltage change is far less than 100mV. In addition to the system error, it is difficult for controller 1 to effectively identify the change of output voltage, or a very high-precision controller 1 and related detection circuits are required to accurately identify it, which will lead to a significant increase in system cost. At the same time, the sampling of controller 1 is usually sampled according to a fixed period. If the software wants to identify whether the voltage of the detection object meets the required 48VAC sinusoidal, it needs to perform complex calculations on all sampling points to determine, and a special data processing controller is required to achieve it, which is relatively expensive; the output voltage changes sinusoidally, and periodic sampling may not be able to accurately collect characteristic voltages such as peaks and valleys for judgment. In order to solve this problem, the present application provides a sinusoidal voltage detection circuit that introduces a bias voltage to sample only the maximum voltage value in each sinusoidal cycle, so as to use the characteristics of the sinusoidal signal to determine whether the sinusoidal function in the cycle is normal, without sampling the data in the entire cycle, thereby improving the sampling efficiency and reducing the sampling cost. Furthermore, the controller 1 adjusts the resistance value of each voltage sampling circuit so that the voltage detection circuit can detect circuits with different output voltages, further improving the scope of application.

[0034] The core of the utility model is to provide a sinusoidal voltage detection circuit and a detection system, so as to reduce the equipment cost on the basis of ensuring the voltage detection accuracy.

[0035] Figure 3 A structural diagram of a sinusoidal voltage peak detection circuit provided in an embodiment of the present application is shown in FIG. Figure 3As shown, the sinusoidal voltage detection circuit includes: a controller 1, a first voltage divider circuit 2, a second voltage divider circuit 3, an operational amplifier 4 and a bias circuit 5; the first voltage divider circuit 2 and the second voltage divider circuit 3 both include a first resistor R1 and a second resistor R2; the first end of the first resistor R1 serves as the first end of each voltage divider circuit, the connection point between the second end of the first resistor R1 and the first end of the second resistor R2 serves as a sampling point of the voltage divider circuit, and the second end of the second resistor R2 serves as the second end of the voltage divider circuit; the first resistor R1 and the second resistor R2 are adjustable resistors, and the resistance value of the first resistor R1 is much greater than the resistance value of the second resistor R2; the first end of the first voltage divider circuit 2 is connected to the first end of the sinusoidal circuit to be measured, and the first voltage divider circuit 2 is connected to the first end of the sinusoidal circuit to be measured. The sampling end of the circuit 2 is connected to the inverting input end of the operational amplifier 4, and the second end of the first voltage divider circuit 2 is grounded; the first end of the second voltage divider circuit 3 is connected to the second end of the sinusoidal circuit to be measured, the sampling end of the second voltage divider circuit 3 is connected to the non-inverting input end of the operational amplifier 4, and the second end of the first voltage divider circuit 2 is grounded; the bias circuit 5 is connected to the sampling end of the first voltage divider circuit 2 to input the bias voltage; the controller 1 is connected to the first resistor R1, the second resistor R2 and the bias circuit 5 to determine the resistance value and the bias voltage of the first resistor R1 and the second resistor R2 according to the corresponding relationship between the detection instruction and the resistance value and the bias voltage; the controller 1 is also connected to the output end of the operational amplifier 4 to obtain the voltage detection value.

[0036] like Figure 3 As shown, the two input terminals of the operational amplifier 4 are in a virtual disconnect state, so: the voltage V p With the reverse input voltage V n Has the following relationship:

[0037]

[0038]

[0039]

[0040]

[0041] And because the operational amplifier 4 is in a virtual short state when it is stable, V p =V n ;

[0042] If the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 in the first voltage divider circuit 2 and the second voltage divider circuit 3 satisfy R1+R4=2(R1+R2) and R2=R4; then the transfer function of the operational amplifier 4 is:

[0043]

[0044] Among them, V1 and V2 are the voltage values ​​of the two sampling terminals of the sampling circuit, V o is the output voltage value of the sinusoidal voltage detection circuit.

[0045] If R1=130.5K, R2=R4=10K, R3=271K;

[0046] V1-V2=V o +65.25;

[0047] Then, the controller 1 can detect the voltage (peak voltage value) only when V1-V2≥65.25.

[0048] Furthermore, the controller 1 is also connected to the first end of the sinusoidal circuit to be tested, and the controller is also connected to the PWM modulation signal input end of the sinusoidal circuit to be tested, so as to determine the time when the extreme value of the output voltage occurs, and obtain the voltage detection value when the voltage extreme value signal is obtained.

[0049] In this solution, the voltage conversion circuit only converts the voltage in the peak and trough sections, so that the 0-5V detection voltage range of the sub-sampling circuit only covers the voltage in the peak or trough section; when the output voltage changes, it can produce obvious changes in the sampling port voltage of the controller 1, making it easier to accurately judge the change in the output voltage, and thus better adjust the accuracy of the output voltage.

[0050] Figure 4 A structural diagram of a sinusoidal voltage valley detection circuit provided in an embodiment of the present application is shown in FIG. Figure 4As shown, the sinusoidal voltage detection circuit includes: a controller 1, a first voltage divider circuit 2, a second voltage divider circuit 3, an operational amplifier 4 and a bias circuit 5; the first voltage divider circuit 2 and the second voltage divider circuit 3 both include a first resistor and a second resistor; the first end of the first resistor is used as the first end of each voltage divider circuit, the second end of the first resistor and the first end of the second resistor are connected at a sampling point of the voltage divider circuit, and the second end of the second resistor is used as the second end of the voltage divider circuit; in a specific implementation, the measurement range of the sinusoidal voltage detection circuit is determined by the resistance ratio of the first resistor to the second resistor. When the controller receives the detection instruction, it determines the voltage amplitude to be measured according to the detection instruction, thereby determining the required amplification factor according to the voltage amplitude, and making the ratio of the resistance value of the first resistor to the resistance value of the second resistor the required amplification factor. It can be understood that when adjusting the resistance ratio of the first resistor to the second resistor, the first resistor and the second resistor can be adjusted at the same time, or only the first resistor and the second resistor can be adjusted, which is not limited here. It can be understood that since the resistance value of the first resistor is much larger than that of the second resistor, if a variable resistor is used as the first resistor, the cost of the equipment will be further increased. Therefore, usually only the second resistor is set as a variable resistor, and the ratio of the first resistor to the second resistor is adjusted by adjusting the resistance value of the second resistor. The first end of the first voltage divider circuit 2 is connected to the first end of the sinusoidal circuit to be measured, the sampling end of the first voltage divider circuit 2 is connected to the inverting input end of the operational amplifier 4, and the second end of the first voltage divider circuit 2 is grounded; the first end of the second voltage divider circuit 3 is connected to the second end of the sinusoidal circuit to be measured, the sampling end of the second voltage divider circuit 3 is connected to the non-inverting input end of the operational amplifier 4, and the second end of the first voltage divider circuit 2 is grounded; the bias circuit 5 is connected to the sampling end of the first voltage divider circuit 2 to input the bias voltage; the controller 1 is connected to the first resistor, the second resistor and the bias circuit 5 to determine the resistance value and bias voltage of the first resistor and the second resistor according to the corresponding relationship between the detection instruction and the resistance value and the bias voltage; the controller 1 is also connected to the output end of the operational amplifier 4 to obtain the voltage detection value.

[0051] Figure 5 A schematic diagram of an effective sampling interval of a sinusoidal peak voltage provided in an embodiment of the present application is shown in FIG. Figure 5 As shown, since the output sinusoidal voltage is obtained by SPWM modulation + conversion + filtering by controller 1 (full-bridge inversion), controller 1 can know the approximate time intervals of the output voltage peaks and troughs in real time; therefore, controller 1 can accurately sample the peak and trough voltages according to the SPWM modulation period to obtain more accurate peak and trough voltages.

[0052] In this embodiment, by optimizing the conversion circuit and cooperating with the method of collecting only the characteristic points of the sinusoidal voltage peak and trough, the coverage range of the sampling port of the controller 1 for the measured sinusoidal AC voltage is reduced, thereby increasing the voltage change amplitude of the measured voltage change at the sampling port of the controller 1, thereby improving the sampling accuracy of the system while reducing the accuracy requirements of the sampling circuit on the hardware circuit and reducing the cost. Since the sinusoidal AC voltage peak and trough are symmetrical, in practical applications, only one of the peak and trough conversion circuits can be used, and sampling both can further improve the accuracy of system sampling and enhance system reliability.

[0053] The present application provides a sinusoidal voltage detection circuit, including: a controller, a first voltage divider circuit, a second voltage divider circuit, an operational amplifier and a bias circuit; the first voltage divider circuit is arranged between the first end of the sinusoidal circuit to be measured and the inverting input end of the operational amplifier, and the second voltage divider circuit is arranged between the second end of the sinusoidal circuit to be measured and the non-inverting input end of the operational amplifier; the bias circuit is connected to the first voltage divider circuit or the second voltage divider circuit to provide a bias voltage; the controller is connected to both the first voltage divider circuit and the second voltage divider circuit to determine the resistance and bias voltage of the first voltage divider circuit and the second voltage divider circuit according to the corresponding relationship between the detection instruction and the resistance of the first voltage divider circuit, the resistance of the second voltage divider circuit and the bias voltage; the controller is also connected to the output end of the operational amplifier to obtain the voltage detection value. It can be seen that the technical solution provided by the present application introduces a bias voltage to sample only the maximum voltage value in each sinusoidal cycle, so as to use the characteristics of the sinusoidal signal to judge whether the sinusoidal function in the cycle is normal, without sampling the data in the entire cycle, thereby improving the sampling efficiency and reducing the sampling cost. Furthermore, the controller adjusts the resistance value of each voltage sampling circuit so that the sinusoidal voltage detection circuit can detect circuits with different output voltages, thereby further improving the application range.

[0054] In a specific implementation, the bias circuit 5 includes a bias power supply and a third resistor; a first end of the third resistor is connected to the bias power supply, and a second end of the third resistor is connected to a sampling end of the first voltage divider circuit 2 or the second voltage divider circuit 3. The second end of the third resistor is connected to the sampling end of the first voltage divider circuit 2 to input a bias voltage. The second end of the third resistor is connected to the sampling end of the second voltage divider circuit 3 to output a bias voltage.

[0055] Furthermore, the sinusoidal voltage detection circuit provided by the present application also includes a display unit; the display unit is connected to the controller 1 to obtain and display the voltage detection value, so that the user can view the voltage value output by the circuit to be tested in real time.

[0056] The human-machine interaction device is used to input detection instructions and preset conditions, such as the upper and lower voltage limits, to the controller 1, and to set other software programs of the controller 1. In a specific implementation, the human-machine interaction device can be a keyboard or a touch screen.

[0057] The controller 1 may be provided separately, or may utilize the electronic control unit of the voltage conversion circuit to be tested itself, thereby reducing the hardware cost.

[0058] The alarm device is used to warn of abnormal voltage. The alarm device is controlled by the controller 1 to automatically alarm, so there is no need for frequent human monitoring, which saves labor costs and has good timeliness. It is understandable that the connection between the alarm device and the controller 1 can be a wired connection or a wireless connection.

[0059] In addition, the present application also provides a voltage detection system, such as Figure 6 As shown, Figure 6 The voltage detection system provided includes a sinusoidal voltage detection circuit for collecting wave crests and a sinusoidal voltage detection circuit for collecting wave troughs, thereby further improving the accuracy of the sampling results. The sinusoidal voltage detection circuit includes: a controller, a first voltage divider circuit, a second voltage divider circuit, an operational amplifier and a bias circuit; the first voltage divider circuit is arranged between the first end of the sinusoidal circuit to be measured and the inverting input end of the operational amplifier, and the second voltage divider circuit is arranged between the second end of the sinusoidal circuit to be measured and the non-inverting input end of the operational amplifier; the bias circuit is connected to the first voltage divider circuit or the second voltage divider circuit to provide a bias voltage; the controller is connected to both the first voltage divider circuit and the second voltage divider circuit to determine the resistance value and bias voltage of the first voltage divider circuit and the second voltage divider circuit according to the corresponding relationship between the detection instruction and the resistance value of the first voltage divider circuit, the resistance value of the second voltage divider circuit and the bias voltage; the controller is also connected to the output end of the operational amplifier to obtain the voltage detection value. It can be seen that the technical solution provided by the present application introduces a bias voltage to sample only the maximum voltage value in each sinusoidal cycle, so as to use the characteristics of the sinusoidal signal to determine whether the sinusoidal function in the cycle is normal, without sampling the data in the entire cycle, thereby improving the sampling efficiency and reducing the sampling cost. Furthermore, the controller adjusts the resistance value of each voltage sampling circuit so that the voltage detection circuit can detect circuits with different output voltages, further improving the scope of application.

[0060] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0061] The above is a detailed introduction to the sinusoidal voltage detection circuit and detection system provided by the utility model. 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 various embodiments can be referenced 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 principle of the utility model, the utility model can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the utility model.

[0062] 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 sinusoidal voltage detection circuit, characterized in that: include: A controller (1), a first voltage divider circuit (2), a second voltage divider circuit (3), an operational amplifier (4) and a bias circuit (5); The first voltage divider circuit (2) is arranged between the first end of the sinusoidal circuit to be measured and the inverting input end of the operational amplifier (4), and the second voltage divider circuit (3) is arranged between the second end of the sinusoidal circuit to be measured and the non-inverting input end of the operational amplifier (4); The bias circuit (5) is connected to the first voltage divider circuit (2) or the second voltage divider circuit (3) to provide a bias voltage; The controller (1) is connected to the first voltage divider circuit (2) and the second voltage divider circuit (3) to determine the resistance values ​​of the first voltage divider circuit (2), the second voltage divider circuit (3) and the bias voltage according to the corresponding relationship between the detection instruction and the resistance value of the first voltage divider circuit (2), the resistance value of the second voltage divider circuit (3) and the bias voltage; The controller (1) is also connected to the output end of the operational amplifier (4) to obtain a voltage detection value.

2. The sinusoidal voltage detection circuit according to claim 1, characterized in that: The first voltage divider circuit (2) and the second voltage divider circuit (3) both comprise a first resistor and a second resistor; The first end of the first resistor is used as the first end of the voltage divider circuit and is connected to the sinusoidal circuit to be measured; The second end of the first resistor is connected to the first end of the second resistor, the connection point serves as a sampling point of the voltage divider circuit, and the second end of the second resistor serves as the second end of the voltage divider circuit; wherein the second resistors are adjustable resistors, and the controller (1) is connected to the second resistors to control the ratio of the first resistor to the second resistor to be a value corresponding to a required amplification factor; the required amplification factor is a value determined according to the detection instruction.

3. The sinusoidal voltage detection circuit according to claim 2, characterized in that: The bias circuit includes a bias power supply and a third resistor; The first end of the third resistor is connected to the bias power supply, and the second end of the third resistor is connected to a sampling point of the first voltage divider circuit (2) or the second voltage divider circuit (3) to provide the bias voltage.

4. The sinusoidal voltage detection circuit according to claim 1, characterized in that: The controller (1) is also connected to the PWM modulation signal input terminal of the sinusoidal circuit to be tested, so as to obtain the voltage detection value when a voltage extreme value signal is obtained.

5. The sinusoidal voltage detection circuit according to claim 3, characterized in that: The second end of the third resistor is connected to the sampling end of the first voltage divider circuit (2) to input the bias voltage.

6. The sinusoidal voltage detection circuit according to claim 3, characterized in that: The second end of the third resistor is connected to the sampling end of the second voltage divider circuit (3) to output the bias voltage.

7. The sinusoidal voltage detection circuit according to claim 1, characterized in that: Also includes a display unit; The display unit is connected to the controller (1) to obtain and display the voltage detection value.

8. The sinusoidal voltage detection circuit according to claim 1, characterized in that: It also comprises an alarm unit, which is connected to the controller (1) to send an alarm message when the voltage detection value does not meet a preset condition.

9. The sinusoidal voltage detection circuit according to claim 8, characterized in that: It also comprises a human-machine interaction unit; the human-machine interaction unit is connected to the controller (1) to input the detection instruction and the preset condition.

10. A sinusoidal voltage detection system, characterized in that: The invention comprises the sinusoidal voltage detection circuit as claimed in any one of claims 1 to 9.

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