Charging insulation resistance detection circuit and method

Abstract

The invention provides a charging insulation resistor detection circuit and method, and relates to the technical field of new energy automobiles, the charging insulation resistor detection circuit comprises a first insulation resistor and a second insulation resistor, one end of the first insulation resistor is connected to a positive bus-to-ground end of a charger, and one end of the second insulation resistor is connected to a negative bus-to-ground end of the charger. The other end of the first insulation resistor and the other end of the second insulation resistor are connected to the PE end through a third switch; the first insulation resistor is connected with a first sampling circuit, and the first sampling circuit is connected with a first switching circuit; the second insulation resistor is connected with a second sampling circuit, and the second sampling circuit is connected with a second switching circuit. The sampling circuit and the switching circuit which are connected with the insulation resistor are arranged, the resistance value of the insulation resistor can be calculated after sampling is carried out through a single channel, therefore, danger is avoided, the circuit is simple, and the detection cost is further reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and in particular to a charging insulation resistance detection circuit; in addition, the present invention also relates to a charging insulation resistance detection method. Background Art

[0002] As new energy vehicles increase their range requirements, battery voltages are also gradually increasing. This increase in battery voltage also places increasing demands on electrical safety. High-power output must ensure user safety. Insulation testing detects leakage between the output and the outer casing. For example, if the insulation resistance is low, the output electricity can leak to the outer casing, making it electrically charged and potentially dangerous. Summary of the Invention

[0003] To address the problems of the prior art, at least one embodiment of the present invention provides a charging insulation resistance detection circuit. This circuit can calculate the insulation resistance value through single-channel sampling, thereby avoiding potential hazards. The simplicity of the circuit further reduces detection costs. To this end, at least one embodiment of the present invention also provides a charging insulation resistance detection method.

[0004] In a first aspect, the present invention provides a charging insulation resistance detection circuit, comprising a first insulation resistor and a second insulation resistor, wherein one end of the first insulation resistor is connected to the positive bus of the charger to the ground, one end of the second insulation resistor is connected to the negative bus of the charger to the ground, and the other end of the first insulation resistor and the other end of the second insulation resistor are both connected to the PE terminal through a third switch; the first insulation resistor is connected to a first sampling circuit, which is connected to a first switching circuit; the second insulation resistor is connected to a second sampling circuit, which is connected to a second switching circuit.

[0005] Preferably, in a charging insulation resistance detection circuit provided by the present invention, the first sampling circuit includes a first sampling resistor and a first voltage-dividing resistor, one end of the first voltage-dividing resistor is connected to one end of the first insulation resistor, the other end of the first voltage-dividing resistor is connected to one end of the first sampling resistor, and the other end of the first sampling resistor is connected to the other end of the first insulation resistor.

[0006] Preferably, the present invention provides a charging insulation resistance detection circuit, wherein the first switching circuit includes a first switch and a third voltage-dividing resistor, one end of the third voltage-dividing resistor is connected to one end of the first voltage-dividing resistor, the other end of the third voltage-dividing resistor is connected to one end of the first switch, and the other end of the first switch is connected to the other end of the first sampling resistor.

[0007] Preferably, in the charging insulation resistance detection circuit provided by the present invention, the first switch is a remotely controllable electronic switch.

[0008] Preferably, in a charging insulation resistance detection circuit provided by the present invention, the second sampling circuit includes a second sampling resistor and a second voltage divider resistor, one end of the second sampling resistor is connected to one end of the second insulation resistor, the other end of the second sampling resistor is connected to one end of the second voltage divider resistor, and the other end of the second voltage divider resistor is connected to the other end of the second insulation resistor.

[0009] Preferably, in a charging insulation resistance detection circuit provided by the present invention, the second switching circuit includes a second switch and a fourth voltage-dividing resistor, one end of the fourth voltage-dividing resistor is connected to one end of the second sampling resistor, the other end of the fourth voltage-dividing resistor is connected to one end of the second switch, and the other end of the second switch is connected to the other end of the second voltage-dividing resistor.

[0010] Preferably, in the charging insulation resistance detection circuit provided by the present invention, the second switch is a remotely controllable electronic switch.

[0011] Preferably, in the charging insulation resistance detection circuit provided by the present invention, the third switch is a remotely controllable electronic switch.

[0012] In a second aspect, the present invention further provides a charging insulation resistance detection method, which uses the charging insulation resistance detection circuit of the first aspect, and the method includes: The sampled voltage is obtained by sampling the second sampling resistor, and the voltage value of the first sampling resistor and the voltage value of the PE terminal are calculated and expressed by the following formula 1 and formula 2: Vpe=u2*(R2+r2) / r2 Equation 1; u1=(Va-Vpe)* r1 / (R1+r1) Formula 2; Wherein, Vpe is the voltage value of the PE terminal, u2 is the voltage sampling value of the second sampling resistor, R2 is the resistance value of the second voltage divider resistor, r2 is the resistance value of the second sampling resistor, u1 is the voltage sampling value of the first sampling resistor, Va is the voltage value of the positive busbar of the charger to ground, r1 is the resistance value of the first sampling resistor, and R1 is the resistance value of the first voltage divider resistor; When the first switch and the third switch are closed and the second switch is open, a first state is obtained, which is expressed by the following equation 1: V1 / (Rx / / (R1+r1) / / RR1) = V2 / (Ry / / (R2+r2) ) Equation 3; Wherein, V1 is the voltage value of the positive busbar of the charger to ground in the first state, V2 is the voltage value of the negative busbar of the charger to ground in the first state, Rx is the resistance value of the first insulation resistor, Ry is the resistance value of the second insulation resistor, R1 is the resistance value of the first voltage divider resistor, R2 is the resistance value of the second voltage divider resistor, r1 is the resistance value of the first sampling resistor, r2 is the resistance value of the second sampling resistor, and RR1 is the resistance value of the third voltage divider resistor; When the second switch and the third switch are closed and the first switch is open, a second state is obtained, which is expressed by the following equation 2: V1' / (Rx / / (R1+r1)) = V2' / (Ry / / (R2+r2) / / RR2) Equation 4; Wherein, V1' is the voltage value of the positive busbar of the charger to ground in the second state, V2' is the voltage value of the negative busbar of the charger to ground in the second state, Rx is the resistance value of the first insulation resistor, Ry is the resistance value of the second insulation resistor, R1 is the resistance value of the first voltage divider resistor, R2 is the resistance value of the second voltage divider resistor, r1 is the resistance value of the first sampling resistor, r2 is the resistance value of the second sampling resistor, and RR2 is the resistance value of the fourth voltage divider resistor; The resistance values ​​of the first insulation resistor and the second insulation resistor are obtained by using Formula 3 and Formula 4.

[0013] Preferably, in the charging insulation resistance detection method provided by the present invention, the resistance value of the first voltage-dividing resistor is equal to the resistance value of the second voltage-dividing resistor, and the resistance value of the first sampling resistor is equal to the resistance value of the second sampling resistor.

[0014] It can be seen that the charging insulation resistance detection circuit and method provided by the present invention are provided with a sampling circuit and a switching circuit connected to the insulation resistance. The insulation resistance value can be calculated after sampling through a single channel, thereby avoiding the occurrence of danger. In addition, the simple circuit further reduces the detection cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 Shown is a circuit diagram of a charging insulation resistance detection circuit in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0018] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this document, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes 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 sentence "comprises a..." does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0019] [Example 1] In the prior art, as new energy vehicles have increased their requirements for endurance, battery voltage has also gradually increased. This increase in battery voltage has also placed increasing demands on electrical safety. During high-power output, the user's personal safety must be ensured. Insulation testing is the process of detecting whether there is "leakage" between the output and the outer casing. For example, if the insulation resistance is low, the output electricity will leak to the outer casing, causing the outer casing to become charged and potentially dangerous. The embodiments of the present invention provide the following solutions: like Figure 1 As shown, an embodiment of the present invention provides a charging insulation resistance detection circuit, including a first insulation resistor Rx and a second insulation resistor Ry, wherein one end of the first insulation resistor Rx is connected to the positive bus of the charger and the ground, one end of the second insulation resistor Ry is connected to the negative bus of the charger and the ground, and the other end of the first insulation resistor Rx and the other end of the second insulation resistor Ry are both connected to the PE terminal through a third switch K3; the first insulation resistor Rx is connected to a first sampling circuit, which is connected to a first switching circuit; the second insulation resistor Ry is connected to a second sampling circuit, which is connected to a second switching circuit.

[0020] In some embodiments, the first sampling circuit includes a first sampling resistor r1 and a first voltage divider resistor R1, one end of the first voltage divider resistor R1 is connected to one end of the first insulation resistor r1, the other end of the first voltage divider resistor R1 is connected to one end of the first sampling resistor r1, and the other end of the first sampling resistor r1 is connected to the other end of the first insulation resistor Rx.

[0021] It should be noted that the first voltage divider resistor R1 can bear part of the voltage of the first sampling resistor r1, generating a voltage drop to prevent the sampling resistor from burning out due to excessive power. In addition, the first voltage divider resistor R1 is also used to match the transmission line impedance to reduce signal reflection.

[0022] In some embodiments, the first switch circuit includes a first switch K1 and a third voltage-dividing resistor RR1, one end of the third voltage-dividing resistor RR1 is connected to one end of the first voltage-dividing resistor R1, the other end of the third voltage-dividing resistor RR1 is connected to one end of the first switch K1, and the other end of the first switch K1 is connected to the other end of the first sampling resistor r1.

[0023] It should be noted that when the first switch K1 is switched on or off, a high instantaneous current is generated. The third voltage-divider resistor RR1 limits the current peak, protecting the switch from damage. Furthermore, the first switch K1 may also generate an arc when disconnecting the load. The third voltage-divider resistor RR1 reduces the arcing capability and prolongs the life of the switch.

[0024] In some embodiments, the first switch is a remotely controllable electronic switch, so that engineers can remotely operate it, thereby improving controllability.

[0025] In some embodiments, the second sampling circuit includes a second sampling resistor r2 and a second voltage divider resistor R2, one end of the second sampling resistor r2 is connected to one end of the second insulation resistor Ry, the other end of the second sampling resistor r2 is connected to one end of the second voltage divider resistor R2, and the other end of the second voltage divider resistor R2 is connected to the other end of the second insulation resistor Ry.

[0026] It should be noted that the second voltage divider resistor R2 can bear part of the voltage of the second sampling resistor r2, generating a voltage drop to prevent the sampling resistor from burning out due to excessive power. In addition, the second sampling resistor r2 is also used to match the transmission line impedance to reduce signal reflection.

[0027] In some embodiments, the second switch circuit includes a second switch K2 and a fourth voltage-dividing resistor RR2, one end of the fourth voltage-dividing resistor RR2 is connected to one end of the second sampling resistor R2, the other end of the fourth voltage-dividing resistor RR2 is connected to one end of the second switch K2, and the other end of the second switch K2 is connected to the other end of the second voltage-dividing resistor R2.

[0028] It should be noted that when the second switch K2 is switched on or off, a high instantaneous current is generated. The fourth voltage-divider resistor RR2 can limit the current peak, protecting the switch from damage. Furthermore, the second switch K2 may also generate an arc when disconnecting the load. The fourth voltage-divider resistor RR2 can reduce the arcing capability and extend the life of the switch.

[0029] In some embodiments, the second switch is a remotely controllable electronic switch, so that engineers can remotely operate it, thereby improving controllability.

[0030] In some embodiments, the third switch is a remotely controllable electronic switch, so that engineers can remotely operate it, thereby improving controllability.

[0031] [Example 2] An embodiment of the present invention further provides a charging insulation resistance detection method, which uses the charging insulation resistance detection circuit of embodiment 1. The method includes: The sampled voltage is obtained by sampling the second sampling resistor, and the voltage value of the first sampling resistor and the voltage value of the PE terminal are calculated and expressed by the following formula 1 and formula 2: Vpe=u2*(R2+r2) / r2 Equation 1; u1=(Va-Vpe)* r1 / (R1+r1) Formula 2; Among them, Vpe is the voltage value of the PE terminal, u2 is the voltage sampling value of the second sampling resistor, R2 is the resistance value of the second voltage divider resistor, r2 is the resistance value of the second sampling resistor, u1 is the voltage sampling value of the first sampling resistor, Va is the positive bus voltage value of the charger to ground, r1 is the resistance value of the first sampling resistor, and R1 is the resistance value of the first voltage divider resistor.

[0032] It should be noted that the voltages of the charger's positive and negative busbars to ground serve as insulation detection voltages. That is, the positive busbar voltage to ground is Va, the negative busbar voltage to ground is Vb, and Va+Vb=V. Specifically, a suitable voltage sampling ground is selected, with the charger's negative output, DC-, as the sampling ground, where Vb=0 and Va=V. By sampling the voltage sampled by the second sampling resistor, the voltage at the PE terminal and the voltage sampled by the first sampling resistor can be calculated.

[0033] When the first switch and the third switch are closed and the second switch is open, a first state is obtained, which is expressed by the following equation 1: V1 / (Rx / / (R1+r1) / / RR1) = V2 / (Ry / / (R2+r2) ) Equation 3; Wherein, V1 is the voltage value of the positive busbar of the charger to ground in the first state, V2 is the voltage value of the negative busbar of the charger to ground in the first state, Rx is the resistance value of the first insulation resistor, Ry is the resistance value of the second insulation resistor, R1 is the resistance value of the first voltage divider resistor, R2 is the resistance value of the second voltage divider resistor, r1 is the resistance value of the first sampling resistor, r2 is the resistance value of the second sampling resistor, and RR1 is the resistance value of the third voltage divider resistor; When the second switch and the third switch are closed and the first switch is open, a second state is obtained, which is expressed by the following equation 2: V1' / (Rx / / (R1+r1)) = V2' / (Ry / / (R2+r2) / / RR2) Equation 4; Wherein, V1' is the voltage value of the positive busbar of the charger to ground in the second state, V2' is the voltage value of the negative busbar of the charger to ground in the second state, Rx is the resistance value of the first insulation resistor, Ry is the resistance value of the second insulation resistor, R1 is the resistance value of the first voltage divider resistor, R2 is the resistance value of the second voltage divider resistor, r1 is the resistance value of the first sampling resistor, r2 is the resistance value of the second sampling resistor, and RR2 is the resistance value of the fourth voltage divider resistor; The resistance values ​​of the first and second insulation resistors are obtained using Equations 3 and 4. Furthermore, under normal charging conditions, the first, second, and third switches are all disconnected. The battery voltage in the circuit can be calculated by comparing the voltage sampled by the second sampling resistor with the negative bus-to-ground voltage, the resistor voltage divider method, and the volt-ampere characteristic.

[0034] In some embodiments, the resistance of the first voltage-dividing resistor is equal to the resistance of the second voltage-dividing resistor, and the resistance of the first sampling resistor is equal to the resistance of the second sampling resistor, thereby simplifying calculation complexity.

[0035] In summary, embodiments 1-2 of the present invention provide a charging insulation resistance detection circuit and method, in which a sampling circuit and a switching circuit connected to the insulation resistance are provided. The insulation resistance value can be calculated after sampling through a single channel, thereby avoiding the occurrence of danger. In addition, the simplicity of the circuit further reduces the detection cost.

[0036] The above content is only a specific embodiment of the present application, and the protection scope of the present application is not limited thereto. Those skilled in the art may make changes or substitutions within the technical scope disclosed in the present application, and these changes or substitutions should all be within the protection scope of the present application.

[0037] Those skilled in the art will appreciate that although some embodiments described herein include some features and not others included in other embodiments, the combination of features from different embodiments is intended to be within the scope of the invention and to form different embodiments.

[0038] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A charging insulation resistance detection circuit, characterized in that: The device includes a first insulation resistor and a second insulation resistor, one end of the first insulation resistor is connected to the positive bus of the charger and the ground, one end of the second insulation resistor is connected to the negative bus of the charger and the ground, and the other end of the first insulation resistor and the other end of the second insulation resistor are both connected to the PE terminal through a third switch; the first insulation resistor is connected to a first sampling circuit, which is connected to a first switching circuit; the second insulation resistor is connected to a second sampling circuit, which is connected to a second switching circuit.

2. The charging insulation resistance detection circuit according to claim 1, characterized in that: The first sampling circuit includes a first sampling resistor and a first voltage-dividing resistor, one end of the first voltage-dividing resistor is connected to one end of the first insulation resistor, the other end of the first voltage-dividing resistor is connected to one end of the first sampling resistor, and the other end of the first sampling resistor is connected to the other end of the first insulation resistor.

3. The charging insulation resistance detection circuit according to claim 2, characterized in that: The first switching circuit includes a first switch and a third voltage-dividing resistor, one end of the third voltage-dividing resistor is connected to one end of the first voltage-dividing resistor, the other end of the third voltage-dividing resistor is connected to one end of the first switch, and the other end of the first switch is connected to the other end of the first sampling resistor.

4. The charging insulation resistance detection circuit according to claim 3, characterized in that: The first switch is a remotely controllable electronic switch.

5. The charging insulation resistance detection circuit according to claim 1, wherein: The second sampling circuit includes a second sampling resistor and a second voltage-dividing resistor, one end of the second sampling resistor is connected to one end of the second insulation resistor, the other end of the second sampling resistor is connected to one end of the second voltage-dividing resistor, and the other end of the second voltage-dividing resistor is connected to the other end of the second insulation resistor.

6. The charging insulation resistance detection circuit according to claim 4, characterized in that: The second switching circuit includes a second switch and a fourth voltage-dividing resistor, one end of the fourth voltage-dividing resistor is connected to one end of the second sampling resistor, the other end of the fourth voltage-dividing resistor is connected to one end of the second switch, and the other end of the second switch is connected to the other end of the second voltage-dividing resistor.

7. The charging insulation resistance detection circuit according to claim 6, characterized in that: The second switch is a remotely controllable electronic switch.

8. The charging insulation resistance detection circuit according to claim 1, wherein: The third switch is a remotely controllable electronic switch.

9. A charging insulation resistance detection method, characterized in that: Applying the charging insulation resistance detection circuit according to any one of claims 1 to 8, the method comprises: The sampled voltage is obtained by sampling the second sampling resistor, and the voltage value of the first sampling resistor and the voltage value of the PE terminal are calculated and expressed by the following formula 1 and formula 2: Vpe=u2*(R2+r2) / r2 Equation 1; u1=(Va-Vpe)* r1 / (R1+r1) Formula 2; Wherein, Vpe is the voltage value of the PE terminal, u2 is the voltage sampling value of the second sampling resistor, R2 is the resistance value of the second voltage divider resistor, r2 is the resistance value of the second sampling resistor, u1 is the voltage sampling value of the first sampling resistor, Va is the voltage value of the positive busbar of the charger to ground, r1 is the resistance value of the first sampling resistor, and R1 is the resistance value of the first voltage divider resistor; When the first switch and the third switch are closed and the second switch is open, a first state is obtained, which is expressed by the following equation 1: V1 / (Rx / / (R1+r1) / / RR1) = V2 / (Ry / / (R2+r2) ) Equation 3; Wherein, V1 is the voltage value of the positive busbar of the charger to ground in the first state, V2 is the voltage value of the negative busbar of the charger to ground in the first state, Rx is the resistance value of the first insulation resistor, Ry is the resistance value of the second insulation resistor, R1 is the resistance value of the first voltage divider resistor, R2 is the resistance value of the second voltage divider resistor, r1 is the resistance value of the first sampling resistor, r2 is the resistance value of the second sampling resistor, and RR1 is the resistance value of the third voltage divider resistor; When the second switch and the third switch are closed and the first switch is open, a second state is obtained, which is expressed by the following equation 2: V1' / (Rx / / (R1+r1)) = V2' / (Ry / / (R2+r2) / / RR2) Equation 4; Wherein, V1' is the voltage value of the positive busbar of the charger to ground in the second state, V2' is the voltage value of the negative busbar of the charger to ground in the second state, Rx is the resistance value of the first insulation resistor, Ry is the resistance value of the second insulation resistor, R1 is the resistance value of the first voltage divider resistor, R2 is the resistance value of the second voltage divider resistor, r1 is the resistance value of the first sampling resistor, r2 is the resistance value of the second sampling resistor, and RR2 is the resistance value of the fourth voltage divider resistor; The resistance values ​​of the first insulation resistor and the second insulation resistor are obtained by using Formula 3 and Formula 4.

10. The charging insulation resistance detection method according to claim 9, characterized in that: The resistance value of the first voltage-dividing resistor is equal to the resistance value of the second voltage-dividing resistor, and the resistance value of the first sampling resistor is equal to the resistance value of the second sampling resistor.

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