Insulation detection circuit based on square wave voltage and electronic equipment

Abstract

The invention provides an insulation detection circuit based on square wave voltage and electronic equipment, and the insulation detection circuit comprises an AC / DC conversion unit, a square wave generation unit, a first insulation detection unit, a first resistance comparison unit, a second insulation detection unit and a second resistance comparison unit which form two detection groups. A direct-current high-voltage positive line and a direct-current high-voltage negative line are detected respectively, and a positive line detection voltage output by the first insulation detection unit is compared with a square wave detection voltage output by the square wave generation unit so as to judge whether the insulating layer of the positive line is qualified or not; and the negative line detection voltage output by the second insulation detection unit is compared with the square wave detection voltage output by the square wave generation unit so as to judge whether the insulating layer of the negative line is qualified or not.

Description

Technical Field

[0001] This application relates to the technical field of insulation detection, and particularly to an insulation detection circuit and an electronic device based on a square-wave voltage. Background Art

[0002] Currently, whether it is photovoltaic products or other power electronic products of new energy, high-voltage direct current is the general trend. Therefore, the safety requirements for the insulation layer of DC transmission lines are getting higher and higher. The existing insulation detection circuits use current sensors or Hall sensors, which are complex to control and also have problems such as being easily interfered with, having insufficient accuracy, and being expensive. Summary of the Invention

[0003] This application provides an insulation detection circuit and an electronic device based on a square-wave voltage, which are used to achieve low-cost and high-precision insulation detection.

[0004] In a first aspect, an embodiment of this application provides an insulation detection circuit based on a square-wave voltage. The insulation detection circuit includes: An AC / DC conversion unit. The input terminals of the AC / DC conversion unit are respectively used to connect to the positive line of the DC high voltage and the negative line of the DC high voltage to be detected. The negative line of the DC high voltage is the first grounding terminal, and the output terminal of the AC / DC conversion unit is used to output an alternating voltage; A square-wave generation unit. The input terminals of the square-wave generation unit are respectively connected to the output terminal of the AC / DC conversion unit. The square-wave generation unit is used to output a square-wave detection voltage according to the alternating voltage; A first insulation detection unit. The first input terminal of the first insulation detection unit is connected to the positive line of the DC high voltage, and the second input terminal of the first insulation detection unit is connected to the output terminal of the square-wave generation unit. The first insulation detection unit is used to output a positive-line detection voltage; A first resistance comparison unit. The first input terminal of the first resistance comparison unit is connected to the output terminal of the first insulation detection unit, the second input terminal of the first resistance comparison unit is connected to the output terminal of the square-wave generation unit, and the control terminal of the first resistance comparison unit is connected to the third input terminal of the first insulation detection unit. When it is detected that the positive-line detection voltage is less than the square-wave detection voltage, the first resistance comparison unit is used to output a positive-line alarm signal; A second insulation detection unit. The first input terminal of the second insulation detection unit is connected to the negative line of the DC high voltage, and the second input terminal of the second insulation detection unit is connected to the output terminal of the square-wave generation unit. The second insulation detection unit is used to output a negative-line detection voltage; A second resistance comparison unit, a first input end of the second resistance comparison unit is connected to an output end of the second insulation detection unit, a second input end of the first resistance comparison unit is connected to an output end of the square wave generation unit, a control end of the second resistance comparison unit is connected to a third input end of the second insulation detection unit, and when it is detected that the negative line detection voltage is less than the square wave detection voltage, the first resistance comparison unit is configured to output a negative line alarm signal.

[0005] In a second aspect, an embodiment of the present application provides an electronic device, and the electronic device includes an insulation detection circuit based on a square wave voltage as described in any one of the embodiments of the present application.

[0006] An embodiment of the present application provides an insulation detection circuit based on a square-wave voltage. The insulation detection circuit includes: an AC / DC conversion unit, a square-wave generation unit, a first insulation detection unit, a first resistance comparison unit, a second insulation detection unit, and a second resistance comparison unit. The input terminals of the AC / DC conversion unit are respectively used to connect to the positive line of the DC high voltage and the negative line of the DC high voltage to be detected. The negative line of the DC high voltage is the first grounding terminal. The output terminal of the AC / DC conversion unit is used to output an AC voltage. The input terminals of the square-wave generation unit are respectively connected to the output terminal of the AC / DC conversion unit. The square-wave generation unit is used to output a square-wave detection voltage according to the AC voltage. The first input terminal of the first insulation detection unit is connected to the positive line of the DC high voltage, and the second input terminal of the first insulation detection unit is connected to the output terminal of the square-wave generation unit. The first insulation detection unit is used to output a positive-line detection voltage. The first input terminal of the first resistance comparison unit is connected to the output terminal of the first insulation detection unit, the second input terminal of the first resistance comparison unit is connected to the output terminal of the square-wave generation unit, and the control terminal of the first resistance comparison unit is connected to the third input terminal of the first insulation detection unit. When it is detected that the positive-line detection voltage is less than the square-wave detection voltage, the first resistance comparison unit is used to output a positive-line alarm signal. The first input terminal of the second insulation detection unit is connected to the negative line of the DC high voltage, the second input terminal of the second insulation detection unit is connected to the output terminal of the square-wave generation unit, and the second insulation detection unit is used to output a negative-line detection voltage. The first input terminal of the second resistance comparison unit is connected to the output terminal of the second insulation detection unit, the second input terminal of the first resistance comparison unit is connected to the output terminal of the square-wave generation unit, and the control terminal of the second resistance comparison unit is connected to the third input terminal of the second insulation detection unit. When it is detected that the negative-line detection voltage is less than the square-wave detection voltage, the first resistance comparison unit is used to output a negative-line alarm signal. In the above circuit, a square-wave detection voltage is generated by the square-wave generation unit. The square-wave signal has steep rising and falling edges, which can more sensitively reflect the change of the insulation state, thereby improving the detection accuracy. The first insulation detection unit and the second insulation detection unit respectively detect the positive line and the negative line of the DC high voltage to ensure that the insulation states of the positive and negative poles can be effectively monitored, avoiding the limitation of single-point detection. The first resistance comparison unit and the second resistance comparison unit can quickly judge whether the insulation state is abnormal by comparing the magnitudes of the positive-line detection voltage and the negative-line detection voltage with the square-wave detection voltage. When it is detected that the positive-line or negative-line detection voltage is less than the square-wave detection voltage, the resistance comparison unit will immediately output the corresponding alarm signal to ensure that the system can respond in time and take protection measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0008] Figure 1 It is a schematic block diagram of an insulation detection circuit based on a square wave voltage provided by an embodiment of the present application; Figure 2 It is a partial circuit schematic diagram of an insulation detection circuit based on a square wave voltage provided by an embodiment of the present application; Figure 3 It is a circuit schematic diagram of a first resistor comparison unit provided by an embodiment of the present application; Figure 4 It is a circuit schematic diagram of a second resistor comparison unit provided by an embodiment of the present application; Figure 5 It is a circuit schematic diagram of a control unit provided by an embodiment of the present application. Detailed implementation manners

[0009] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0010] The flowcharts shown in the drawings are only illustrative examples, and do not necessarily include all contents and operations / steps, nor do they necessarily need to be executed in the described order. For example, some operations / steps can also be decomposed, combined, or partially merged, so the actual execution order may be changed according to the actual situation.

[0011] It should also be understood that the terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification of the present application and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms.

[0012] It should be further understood that the term " / and" used in the specification of the present application and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0013] Please refer to Figure 1 , Figure 1It is a schematic block diagram of an insulation detection circuit based on a square wave voltage provided by an embodiment of the present application. As Figure 1 shown, the insulation detection circuit includes: an AC / DC conversion unit, a square wave generation unit, a first insulation detection unit, a first resistance comparison unit, a second insulation detection unit, and a second resistance comparison unit. The input terminals of the AC / DC conversion unit are respectively used to connect to the positive DC high voltage line and the negative DC high voltage line to be detected. The negative DC high voltage line is the first grounding terminal, and the output terminal of the AC / DC conversion unit is used to output an AC voltage. The input terminals of the square wave generation unit are respectively connected to the output terminal of the AC / DC conversion unit, and the square wave generation unit is used to output a square wave detection voltage according to the AC voltage. The first input terminal of the first insulation detection unit is connected to the positive DC high voltage line, the second input terminal of the first insulation detection unit is connected to the output terminal of the square wave generation unit, and the first insulation detection unit is used to output a positive line detection voltage. The first input terminal of the first resistance comparison unit is connected to the output terminal of the first insulation detection unit, the second input terminal of the first resistance comparison unit is connected to the output terminal of the square wave generation unit, and the control terminal of the first resistance comparison unit is connected to the third input terminal of the first insulation detection unit. When it is detected that the positive line detection voltage is less than the square wave detection voltage, the first resistance comparison unit is used to output a positive line alarm signal. The first input terminal of the second insulation detection unit is connected to the negative DC high voltage line, the second input terminal of the second insulation detection unit is connected to the output terminal of the square wave generation unit, and the second insulation detection unit is used to output a negative line detection voltage. The first input terminal of the second resistance comparison unit is connected to the output terminal of the second insulation detection unit, the second input terminal of the first resistance comparison unit is connected to the output terminal of the square wave generation unit, and the control terminal of the second resistance comparison unit is connected to the third input terminal of the second insulation detection unit. When it is detected that the negative line detection voltage is less than the square wave detection voltage, the first resistance comparison unit is used to output a negative line alarm signal.

[0014] An embodiment of the present application provides an insulation detection circuit based on a square-wave voltage. The insulation detection circuit includes: an AC / DC conversion unit, a square-wave generation unit, a first insulation detection unit, a first resistance comparison unit, a second insulation detection unit, and a second resistance comparison unit. The input terminals of the AC / DC conversion unit are respectively used to connect to the positive line and the negative line of the DC high voltage to be detected. The negative line of the DC high voltage is the first grounding terminal, and the output terminal of the AC / DC conversion unit is used to output an AC voltage. The input terminals of the square-wave generation unit are respectively connected to the output terminal of the AC / DC conversion unit, and the square-wave generation unit is used to output a square-wave detection voltage according to the AC voltage. The first input terminal of the first insulation detection unit is connected to the positive line of the DC high voltage, the second input terminal of the first insulation detection unit is connected to the output terminal of the square-wave generation unit, and the first insulation detection unit is used to output a positive-line detection voltage. The first input terminal of the first resistance comparison unit is connected to the output terminal of the first insulation detection unit, the second input terminal of the first resistance comparison unit is connected to the output terminal of the square-wave generation unit, and the control terminal of the first resistance comparison unit is connected to the third input terminal of the first insulation detection unit. When it is detected that the positive-line detection voltage is less than the square-wave detection voltage, the first resistance comparison unit is used to output a positive-line alarm signal. The first input terminal of the second insulation detection unit is connected to the negative line of the DC high voltage, the second input terminal of the second insulation detection unit is connected to the output terminal of the square-wave generation unit, and the second insulation detection unit is used to output a negative-line detection voltage. The first input terminal of the second resistance comparison unit is connected to the output terminal of the second insulation detection unit, the second input terminal of the first resistance comparison unit is connected to the output terminal of the square-wave generation unit, and the control terminal of the second resistance comparison unit is connected to the third input terminal of the second insulation detection unit. When it is detected that the negative-line detection voltage is less than the square-wave detection voltage, the first resistance comparison unit is used to output a negative-line alarm signal. In the above circuit, a square-wave detection voltage is generated by the square-wave generation unit. The square-wave signal has steep rising and falling edges, which can more sensitively reflect the change of the insulation state, thereby improving the detection accuracy. The first insulation detection unit and the second insulation detection unit respectively detect the positive line and the negative line of the DC high voltage to ensure that the insulation states of both the positive and negative poles can be effectively monitored, avoiding the limitation of single-point detection. The first resistance comparison unit and the second resistance comparison unit can quickly judge whether the insulation state is abnormal by comparing the magnitudes of the positive-line detection voltage and the negative-line detection voltage with the square-wave detection voltage. When it is detected that the positive-line or negative-line detection voltage is less than the square-wave detection voltage, the resistance comparison unit will immediately output the corresponding alarm signal to ensure that the system can respond in time and take protection measures.

[0015] To more clearly introduce the technical solution of the present application, the technical solution of the present application will also be introduced through specific embodiments below. It should be noted that the specific embodiment is used to expand the description of the technical solution of the present application, rather than limiting the present application.

[0016] In some embodiments, the output terminal of the AC / DC conversion unit includes: a first AC terminal L and a second AC terminal R. The square-wave generating unit includes: a first voltage transformer TX1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a first comparator U1, and a second comparator U2.

[0017] The first terminal of the first voltage transformer TX1 is connected to the first AC terminal L. The second terminal of the first voltage transformer TX1 is connected to the first terminal of the first resistor R1. The third terminal of the first voltage transformer TX1 is connected to the second AC terminal R. The fourth terminal of the first voltage transformer TX1 is connected to the first terminal of the second resistor R2. The second terminal of the first resistor R1 is respectively connected to the first terminal of the first comparator U1 and the first terminal of the third resistor R3. The second terminal of the second resistor R2 is respectively connected to the second terminal of the first comparator U1 and the first terminal of the fourth resistor R4. The second terminal of the fourth resistor R4 is connected to the first ground terminal. The second terminal of the third resistor R3 is respectively connected to the output terminal of the first comparator U1 and the first terminal of the fifth resistor R5. The second terminal of the fifth resistor R5 is respectively connected to the first terminal of the sixth resistor R6 and the first terminal of the seventh resistor R7. The second terminal of the sixth resistor R6 is connected to the first preset voltage source V3.3. The second terminal of the seventh resistor R7 is connected to the second terminal of the second comparator U2. The first terminal of the second comparator U2 is respectively connected to the first terminal of the eighth resistor R8 and the first terminal of the ninth resistor R9. The second terminal of the eighth resistor R8 is connected to the first preset voltage source V3.3. The second terminal of the ninth resistor R9 is connected to the first ground terminal. The output terminal of the second comparator U2 is connected to the first terminal of the tenth resistor R10. The second terminal of the tenth resistor R10 is the output terminal of the square-wave generating unit.

[0018] In some embodiments, the AC / DC conversion unit includes: a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, a sixth diode D6, a seventh diode D7, an eighth diode D8, a first switching transistor Q1, a second switching transistor Q2, a third switching transistor Q3, a fourth switching transistor Q4, a first capacitor C1, a second capacitor C2, a resonant capacitor Cr1, a resonant inductor Lr1, and a transformer T1.

[0019] In some embodiments, the first insulation detection unit includes: an eleventh resistor R11, a twelfth resistor R12, a first relay K1, a fifth switching transistor Q5, a second voltage transformer TX2, a third voltage transformer TX3, a thirteenth resistor R13, and a fourteenth resistor R14.

[0020] The first end of the eleventh resistor R11 is connected to the positive line of the DC high voltage, and the second end of the eleventh resistor R11 is connected to the first end of the first relay K1. The second end of the first relay K1 is connected to the first end of the eleventh resistor R11. The second end of the eleventh resistor R11 is respectively connected to the first end of the twelfth resistor R12 and the second preset voltage source V5. The second end of the twelfth resistor R12 is respectively connected to the second insulation detection unit and the controlled end of the fifth switching tube Q5. The first end of the fifth switching tube Q5 is connected to the third end of the first relay K1, and the second end of the fifth switching tube Q5 is connected to the first grounding end. The fourth end of the first relay K1 is connected to the first end of the second voltage transformer TX2. The second end of the second voltage transformer TX2 is connected to the output end of the square wave generating unit. The third end of the second voltage transformer TX2 is connected to the first grounding end. The fourth end of the second voltage transformer TX2 is respectively connected to the first end of the thirteenth resistor R13 and the first end of the third voltage transformer TX3. The second end of the third voltage transformer TX3 is the output end of the first insulation detection unit. The third end of the third voltage transformer TX3 is connected to the first grounding end. The fourth end of the third voltage transformer TX3 is respectively connected to the second end of the thirteenth resistor R13 and the first end of the fourteenth resistor R14. The second end of the fourteenth resistor R14 is connected to the positive line of the DC high voltage. The first end of the fourteenth resistor R14 is also connected to the preset second grounding end.

[0021] Wherein, when the first resistor comparison unit does not output a negative line warning signal, the first resistor comparison unit controls the controlled end of the fifth switching tube Q5 at a low level, the first relay K1 is in a closed state, and the first insulation detection unit is closed.

[0022] In some embodiments, the first resistor comparison unit includes: a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a third comparator U3, and a sixth switching tube Q6.

[0023] The first end of the fifteenth resistor R15 is connected to the controlled end of the sixth switching tube Q6, and the second end of the fifteenth resistor R15 is connected to the first end of the sixth switching tube Q6. The second end of the sixth switching tube Q6 is connected to the first grounding end, and the controlled end of the sixth switching tube Q6 is connected to the first end of the fifteenth resistor R15. The second end of the fifteenth resistor R15 is connected to the output end of the third comparator U3. The first end of the third comparator U3 is connected to the first end of the sixteenth resistor R16, and the second end of the sixteenth resistor R16 is connected to the output end of the first insulation detection unit. The second end of the third comparator U3 is connected to the first end of the seventeenth resistor R17, and the second end of the seventeenth resistor R17 is respectively connected to the first end of the eighteenth resistor R18 and the first end of the nineteenth resistor R19. The second end of the eighteenth resistor R18 is connected to the output end of the square wave generating unit. The second end of the nineteenth resistor R19 is connected to the first grounding end.

[0024] In some embodiments, the second insulation detection unit includes: a twentieth resistor R20, a twenty-first resistor R21, a second relay K2, a seventh switching transistor Q7, a fourth voltage transformer TX4, a fifth voltage transformer TX5, a twenty-second resistor R22, and a twenty-third resistor R23.

[0025] The first end of the twentieth resistor R20 is connected to the positive DC high-voltage line, and the second end of the twentieth resistor R20 is connected to the first end of the second relay K2. The second end of the second relay K2 is connected to the first end of the twentieth resistor R20. The second end of the twentieth resistor R20 is respectively connected to the first end of the twenty-first resistor R21 and the second preset voltage source V5. The second end of the twenty-first resistor R21 is respectively connected to the second insulation detection unit and the controlled end of the seventh switching transistor Q7. The first end of the seventh switching transistor Q7 is connected to the third end of the second relay K2, and the second end of the seventh switching transistor Q7 is connected to the first grounding end. The fourth end of the second relay K2 is connected to the first end of the fourth voltage transformer TX4. The second end of the fourth voltage transformer TX4 is connected to the output end of the square-wave generating unit. The third end of the fourth voltage transformer TX4 is connected to the first grounding end. The fourth end of the fourth voltage transformer TX4 is respectively connected to the first end of the twenty-second resistor R22 and the first end of the fifth voltage transformer TX5. The second end of the fifth voltage transformer TX5 is the output end of the second insulation detection unit. The third end of the fifth voltage transformer TX5 is connected to the first grounding end. The fourth end of the fifth voltage transformer TX5 is respectively connected to the second end of the twenty-second resistor R22 and the first end of the twenty-third resistor R23. The second end of the twenty-third resistor R23 is connected to the negative DC high-voltage line, and the first end of the twenty-third resistor R23 is also connected to the preset second grounding end.

[0026] Wherein, when the second resistor comparison unit does not output a negative-line warning signal, the second resistor comparison unit controls the controlled end of the seventh switching transistor Q7 at a low level, the second relay K2 is in a closed state, and the second insulation detection unit is turned off.

[0027] In some embodiments, the second resistor comparison unit includes: a twenty-fourth resistor R24, a twenty-fifth resistor R25, a twenty-sixth resistor R26, a twenty-seventh resistor R27, a twenty-eighth resistor R28, a fourth comparator U4, and an eighth switching transistor Q8.

[0028] The first end of the twenty-fourth resistor R24 is connected to the controlled end of the eighth switching transistor Q8, and the second end of the twenty-fourth resistor R24 is connected to the first end of the eighth switching transistor Q8. The second end of the eighth switching transistor Q8 is connected to the first ground terminal, and the controlled end of the eighth switching transistor Q8 is connected to the first end of the twenty-fourth resistor R24. The second end of the twenty-fourth resistor R24 is connected to the output terminal of the fourth comparator U4. The first end of the fourth comparator U4 is connected to the first end of the twenty-fifth resistor R25, and the second end of the twenty-fifth resistor R25 is connected to the output terminal of the second insulation detection unit. The second end of the fourth comparator U4 is connected to the first end of the twenty-sixth resistor R26, and the second end of the twenty-sixth resistor R26 is respectively connected to the first end of the twenty-seventh resistor R27 and the first end of the twenty-eighth resistor R28. The second end of the twenty-seventh resistor R27 is connected to the output terminal of the square wave generating unit. The second end of the twenty-eighth resistor R28 is connected to the first ground terminal.

[0029] It should be noted that, as Figure 5 shown, the insulation detection circuit based on square wave voltage provided in the embodiment of the present application further includes a control unit, which is an MCU, and the control unit is connected to the first sampling voltage VS1, the second sampling voltage VS2, Ctr1 and Ctr2.

[0030] In one embodiment, as Figure 2 shown, the AC sinusoidal AC voltage passes through the first AC terminal L, the second AC terminal N line, the first voltage transformer TX1, the first resistor R1, the second resistor R2 and the first comparator U1 to obtain a sinusoidal sampling voltage. The DC voltage after the sinusoidal sampling voltage is divided by the fifth resistor R5 and the sixth resistor R6 is superimposed on V3.3 to form a mixed voltage. The mixed voltage is input to the positive input pin of the second comparator U2 and compared with the negative input pin of the second comparator U2 to generate a square wave voltage with a duty cycle of 0.5. The square wave voltage with a duty cycle of 0.5 outputs a square wave detection voltage Vf through the tenth resistor R10. The square wave detection voltage Vf is respectively sent to the first insulation detection unit 13 and the second insulation detection unit 15.

[0031] In the first insulation detection unit 13, according to Ohm's law U = IR, it can be obtained that VS1 / R13 = Vf / (R14 + R13), and after deformation, R14 = (Vf * 13 - VS1 * 13) / VS1. Similarly, in the second insulation detection unit 15, R23 = (Vf * R22 - VS2 * R22) / VS2.

[0032] As Figure 2 and Figure 3As shown in the figure, when detecting the insulation layer of the DC high-voltage positive line (HVDC+), the square-wave detection voltage Vf forms a loop through the second voltage transformer, the first relay K1, the DC high-voltage positive line (HVDC+), the thirteenth resistor R13, the second grounding terminal PE, and the fourteenth resistor R14. The first sampling voltage VS1 sampled by the third voltage transformer TX3 is sent through the sixteenth resistor R16 to the positive input pin of the third comparator U3 for comparison with the reference voltage Vref (the eighteenth resistor R18 and the nineteenth resistor R19 are used to divide the square-wave reference voltage Vf to obtain the reference voltage Vref) at the negative input pin of the third comparator U3. Assume that the eighteenth resistor R18 is the national standard insulation resistance value, and the nineteenth resistor R19 and the thirteenth resistor R13 have the same resistance value. Therefore, if the first sampling voltage VS1 is greater than the square-wave reference voltage Vf, it can be deduced that the fourteenth resistor R14 (insulation resistance) is greater than the national standard insulation resistance value of the eighteenth resistor R18, proving that the insulation resistance from the DC high-voltage positive line (HVDC+) to the second grounding terminal PE meets the requirements and will not cause harm to personal safety. The third comparator U3 then outputs a high level to the relevant alarm or other electronic devices and apparatuses to notify the user that the insulation resistance from the DC high-voltage positive line (HVDC+) to the second grounding terminal PE meets the requirements and is safe. If the first sampling voltage VS1 is less than the square-wave reference voltage Vf, it proves that the insulation resistance from the DC high-voltage positive line (HVDC+) to the second grounding terminal PE is less than the national standard insulation resistance value and does not meet the requirements. When the first sampling voltage VS1 is compared with the square-wave reference voltage Vf, the third comparator U3 outputs a low level to the relevant alarm or other electronic devices and apparatuses to notify the user that the insulation resistance from the DC high-voltage positive line (HVDC+) to the second grounding terminal PE is small and there is a risk of electric shock, and professional personnel are required to conduct inspections until the first sampling voltage VS1 is greater than the square-wave reference voltage Vf.

[0033] It should be noted that, as Figure 2 and Figure 4 shown, the processes of detecting the DC high-voltage negative line (HVDC-) and the DC high-voltage positive line (HVDC+) are the same and will not be elaborated here.

[0034] In some embodiments, as Figure 2 、 Figure 3 and Figure 4 shown, in the case of safe detection, the bases of the sixth switching transistor Q6 and the eighth switching transistor Q8 are both at high level, and the bases of the fifth switching transistor Q5 and the seventh switching transistor Q7 are at low level. Then Ctr1 and Ctr2 are at low level, closing the first insulation detection unit 13 and the second insulation detection unit 15, and the AC / DC conversion unit 11 can start to output high-voltage DC voltage.

[0035] An embodiment of the present application provides an electronic device, and the electronic device includes an insulation detection circuit based on a square-wave voltage as described in any one of the embodiments of the present application.

[0036] As described above, the above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. An insulation detection circuit based on square wave voltage, characterized in that: The insulation detection circuit comprises: An AC / DC conversion unit, wherein the input end of the AC / DC conversion unit is respectively used to connect a DC high-voltage positive line and a DC high-voltage negative line to be detected, the DC high-voltage negative line is the first grounding terminal, and the output end of the AC / DC conversion unit is used to output an AC voltage; A square wave generating unit, wherein the input ends of the square wave generating unit are respectively connected to the output ends of the AC / DC conversion unit, and the square wave generating unit is used to output a square wave detection voltage according to the AC voltage; a first insulation detection unit, wherein a first input end of the first insulation detection unit is connected to the DC high voltage positive line, a second input end of the first insulation detection unit is connected to an output end of the square wave generating unit, and the first insulation detection unit is used to output a positive line detection voltage; a first resistance comparison unit, wherein a first input end of the first resistance comparison unit is connected to an output end of the first insulation detection unit, a second input end of the first resistance comparison unit is connected to an output end of the square wave generation unit, a control end of the first resistance comparison unit is connected to a third input end of the first insulation detection unit, and when it is detected that the positive line detection voltage is less than the square wave detection voltage, the first resistance comparison unit is used to output a positive line alarm signal; a second insulation detection unit, wherein a first input end of the second insulation detection unit is connected to the DC high voltage negative line, a second input end of the second insulation detection unit is connected to the output end of the square wave generating unit, and the second insulation detection unit is used to output a negative line detection voltage; A second resistance comparison unit, wherein a first input terminal of the second resistance comparison unit is connected to an output terminal of the second insulation detection unit, a second input terminal of the first resistance comparison unit is connected to an output terminal of the square wave generating unit, a control terminal of the second resistance comparison unit is connected to a third input terminal of the second insulation detection unit, and when it is detected that the negative line detection voltage is less than the square wave detection voltage, the first resistance comparison unit is used to output a negative line alarm signal.

2. The square wave voltage based insulation detection circuit according to claim 1, characterized in that: The output end of the AC / DC conversion unit includes: a first AC end L and a second AC end R, and the square wave generating unit includes: a first voltage transformer TX1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a first comparator U1 and a second comparator U2; The first end of the first voltage transformer TX1 is connected to the first AC terminal L, the second end of the first voltage transformer TX1 is connected to the first end of the first resistor R1, the third end of the first voltage transformer TX1 is connected to the second AC terminal R, and the fourth end of the first voltage transformer TX1 is connected to the first end of the second resistor R2; the second end of the first resistor R1 is respectively connected to the first end of the first comparator U1 and the first end of the third resistor R3, the second end of the second resistor R2 is respectively connected to the second end of the first comparator U1 and the first end of the fourth resistor R4, and the second end of the fourth resistor R4 is connected to the first ground terminal; the second end of the third resistor R3 is respectively connected to the output end of the first comparator U1, the output end of the ... The first end of the fifth resistor R5 is connected; the second end of the fifth resistor R5 is respectively connected to the first end of the sixth resistor R6 and the first end of the seventh resistor R7; the second end of the sixth resistor R6 is connected to the first preset voltage source V3.3; the second end of the seventh resistor R7 is connected to the second end of the second comparator U2; the first end of the second comparator U2 is respectively connected to the first end of the eighth resistor R8 and the first end of the ninth resistor R9, and the second end of the eighth resistor R8 is connected to the first preset voltage source V3.3; the second end of the ninth resistor R9 is connected to the first ground end; the output end of the second comparator U2 is connected to the first end of the tenth resistor R10, and the second end of the tenth resistor R10 is the output end of the square wave generating unit.

3. The square wave voltage based insulation detection circuit according to claim 1, characterized in that: The AC / DC conversion unit includes: a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, a sixth diode D6, a seventh diode D7, an eighth diode D8, a first switch tube Q1, a second switch tube Q2, a third switch tube Q3, a fourth switch tube Q4, a first capacitor C1, a second capacitor C2, a resonant capacitor Cr1, a resonant inductor Lr1 and a transformer T1.

4. The square wave voltage based insulation detection circuit according to claim 1, characterized in that: The first insulation detection unit includes: an eleventh resistor R11, a twelfth resistor R12, a first relay K1, a fifth switch tube Q5, a second voltage transformer TX2, a third voltage transformer TX3, a thirteenth resistor R13 and a fourteenth resistor R14; The first end of the eleventh resistor R11 is connected to the DC high voltage positive line, and the second end of the eleventh resistor R11 is connected to the first end of the first relay K1; the second end of the first relay K1 is connected to the first end of the eleventh resistor R11; the second end of the eleventh resistor R11 is respectively connected to the first end of the twelfth resistor R12 and the second preset voltage source V5, and the second end of the twelfth resistor R12 is respectively connected to the second insulation detection unit and the controlled end of the fifth switch tube Q5; the first end of the fifth switch tube Q5 is connected to the third end of the first relay K1, and the second end of the fifth switch tube Q5 is connected to the first ground end; the fourth end of the first relay K1 is connected to the first end of the second voltage transformer TX2, and the second voltage transformer TX2 is connected to the first end of the second voltage transformer TX2. The second end of the transformer TX2 is connected to the output end of the square wave generating unit, the third end of the second voltage transformer TX2 is connected to the first grounding end, and the fourth end of the second voltage transformer TX2 is respectively connected to the first end of the thirteenth resistor R13 and the first end of the third voltage transformer TX3; the second end of the third voltage transformer TX3 is the output end of the first insulation detection unit, the third end of the third voltage transformer TX3 is connected to the first grounding end, the fourth end of the third voltage transformer TX3 is respectively connected to the second end of the thirteenth resistor R13 and the first end of the fourteenth resistor R14, the second end of the fourteenth resistor R14 is connected to the DC high voltage positive line, and the first end of the fourteenth resistor R14 is also connected to the preset second grounding end; When the first resistance comparison unit does not output the negative line warning signal, the first resistance comparison unit controls the controlled end of the fifth switch tube Q5 to a low level, the first relay K1 is in a closed state, and the first insulation detection unit is closed.

5. The square wave voltage based insulation detection circuit according to claim 4, characterized in that: The first resistance comparison unit includes: a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a third comparator U3 and a sixth switch tube Q6; The first end of the fifteenth resistor R15 is connected to the controlled end of the sixth switch tube Q6, and the second end of the fifteenth resistor R15 is connected to the first end of the sixth switch tube Q6; the second end of the sixth switch tube Q6 is connected to the first ground end, and the controlled end of the sixth switch tube Q6 is connected to the first end of the fifteenth resistor R15; the second end of the fifteenth resistor R15 is connected to the output end of the third comparator U3; the first end of the third comparator U3 is connected to the first end of the sixteenth resistor R16, and the second end of the sixteenth resistor R16 is connected to the output end of the first insulation detection unit; the second end of the third comparator U3 is connected to the first end of the seventeenth resistor R17, and the second end of the seventeenth resistor R17 is respectively connected to the first end of the eighteenth resistor R18 and the first end of the nineteenth resistor R19; the second end of the eighteenth resistor R18 is connected to the output end of the square wave generating unit; the second end of the nineteenth resistor R19 is connected to the first ground end.

6. The square wave voltage based insulation detection circuit according to claim 1, characterized in that: The second insulation detection unit includes: a twentieth resistor R20, a twenty-first resistor R21, a second relay K2, a seventh switch tube Q7, a fourth voltage transformer TX4, a fifth voltage transformer TX5, a twenty-second resistor R22 and a twenty-third resistor R23; The first end of the 20th resistor R20 is connected to the DC high voltage positive line, and the second end of the 20th resistor R20 is connected to the first end of the second relay K2; the second end of the second relay K2 is connected to the first end of the 20th resistor R20; the second end of the 20th resistor R20 is respectively connected to the first end of the 21st resistor R21 and the second preset voltage source V5, and the second end of the 21st resistor R21 is respectively connected to the second insulation detection unit and the controlled end of the seventh switch tube Q7; the first end of the seventh switch tube Q7 is connected to the third end of the second relay K2, and the second end of the seventh switch tube Q7 is connected to the first ground end; the fourth end of the second relay K2 is connected to the first end of the fourth voltage transformer TX4, and the fourth voltage transformer TX4 is connected to the first end of the fourth voltage transformer TX4. The second end of the fourth voltage transformer TX4 is connected to the output end of the square wave generating unit, the third end of the fourth voltage transformer TX4 is connected to the first grounding end, and the fourth end of the fourth voltage transformer TX4 is respectively connected to the first end of the twenty-second resistor R22 and the first end of the fifth voltage transformer TX5; the second end of the fifth voltage transformer TX5 is the output end of the second insulation detection unit, the third end of the fifth voltage transformer TX5 is connected to the first grounding end, the fourth end of the fifth voltage transformer TX5 is respectively connected to the second end of the twenty-second resistor R22 and the first end of the twenty-third resistor R23, the second end of the twenty-third resistor R23 is connected to the DC high voltage negative line, and the first end of the twenty-third resistor R23 is also connected to the preset second grounding end; When the second resistance comparison unit does not output the negative line warning signal, the second resistance comparison unit controls the controlled end of the seventh switch tube Q7 to a low level, the second relay K2 is in a closed state, and the second insulation detection unit is closed.

7. The square wave voltage based insulation detection circuit according to claim 6, characterized in that: The second resistance comparison unit includes: a twenty-fourth resistor R24, a twenty-fifth resistor R25, a twenty-sixth resistor R26, a twenty-seventh resistor R27, a twenty-eighth resistor R28, a fourth comparator U4 and an eighth switch tube Q8; The first end of the 24th resistor R24 ​​is connected to the controlled end of the eighth switch tube Q8, and the second end of the 24th resistor R24 ​​is connected to the first end of the eighth switch tube Q8; the second end of the eighth switch tube Q8 is connected to the first ground end, and the controlled end of the eighth switch tube Q8 is connected to the first end of the 24th resistor R24; the second end of the 24th resistor R24 ​​is connected to the output end of the fourth comparator U4; the first end of the fourth comparator U4 is connected to the first end of the 25th resistor R25, and the second end of the 25th resistor R25 is connected to the output end of the second insulation detection unit; the second end of the fourth comparator U4 is connected to the first end of the 26th resistor R26, and the second end of the 26th resistor R26 is respectively connected to the first end of the 27th resistor R27 and the first end of the 28th resistor R28; the second end of the 27th resistor R27 is connected to the output end of the square wave generating unit; the second end of the 28th resistor R28 is connected to the first ground end.

8. An electronic device, characterized in that: The electronic device comprises the insulation detection circuit based on square wave voltage as claimed in any one of claims 1 to 7.

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