Bridge arm type insulation detection circuit

Abstract

The utility model provides a bridge arm type insulation detection circuit. The circuit comprises an upper bridge arm insulation sampling circuit, a lower bridge arm insulation sampling circuit and a reverse connection circuit. The upper bridge arm insulation sampling circuit is used for collecting the voltage of the upper bridge arm sampling resistor, the lower bridge arm insulation sampling circuit is used for collecting the voltage of the lower bridge arm sampling resistor, and the voltage of the upper bridge arm sampling resistor and the voltage of the lower bridge arm sampling resistor are combined with known quantity. And comparing the resistance values with the national standard insulation resistance so as to judge whether the insulation resistance is abnormal or not. The utility model relates to the technical field of insulation detection.

Description

Technical Field

[0001] This utility model relates to the field of insulation detection technology, and in particular to a bridge-arm type insulation detection circuit. Background Technology

[0002] An insulation testing circuit is a device used to detect the presence of insulation faults in a circuit. It plays a crucial role in many fields. Regularly testing insulation performance can effectively prevent safety accidents and ensure the normal operation and safety of the system. However, the electrical environment in which it is tested is complex, and the testing circuit is susceptible to interference, leading to inaccurate test results.

[0003] In high-voltage products such as new energy and energy storage systems, the assessment of system safety often employs AC injection for insulation sampling. This method involves injecting an AC signal of a specific frequency into the circuit and then measuring the circuit's response to evaluate the insulation status. However, the AC signal is affected by the circuit's distributed capacitance, which can lead to low final detection accuracy. The presence of distributed capacitance can distort the signal during transmission, thus affecting the accuracy of the detection results. Utility Model Content

[0004] To address the problems existing in the prior art, this utility model proposes a bridge-arm type insulation detection circuit. It aims to solve the problems of low detection accuracy and high production cost of traditional insulation detection circuits.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is: a bridge arm insulation detection circuit, which includes an upper bridge arm insulation sampling circuit, a lower bridge arm insulation sampling circuit, and a reverse connection circuit;

[0006] The upper bridge arm insulation sampling circuit includes a first switch, a first resistor, an upper bridge arm sampling resistor, and a first operational amplifier. One end of the first switch is connected to the positive terminal of the power supply, and the other end is connected to one end of the first resistor. One end of the upper bridge arm sampling resistor and the other end of the first resistor are both connected to the non-inverting input terminal of the first operational amplifier. The other end of the upper bridge arm sampling resistor is connected to the common ground.

[0007] The lower bridge arm insulation sampling circuit includes a second switch, a second resistor, a lower bridge arm sampling resistor, and a second operational amplifier. One end of the second switch is connected to the negative terminal of the power supply, and the other end is connected to one end of the second resistor. One end of the lower bridge arm sampling resistor and the other end of the second resistor are both connected to the non-inverting input terminal of the second operational amplifier. The other end of the lower bridge arm sampling resistor is connected to a common ground. The reverse connection circuit is connected between the lower bridge arm sampling resistor and the common ground.

[0008] Based on the above, the upper bridge arm insulation sampling circuit is used to collect the voltage of the upper bridge arm sampling resistor, and the lower bridge arm insulation sampling circuit is used to collect the voltage of the lower bridge arm sampling resistor. By combining the voltages of the upper and lower bridge arm sampling resistors with known quantities, the equivalent resistance values ​​of the positive terminal to ground and the equivalent resistance values ​​of the negative terminal to ground can be calculated. These values ​​are then compared with the national standard insulation resistance to determine whether the insulation resistance is abnormal. The upper and lower bridge arm insulation sampling circuits are respectively equipped with a first operational amplifier and a second operational amplifier. These amplifiers amplify the collected signals, improving the sensitivity and accuracy of the detection. The reverse connection circuit protects the detection equipment, preventing damage from reverse power supply and reducing maintenance costs.

[0009] Furthermore, the reverse connection circuit includes a first diode, a third resistor, and a third operational amplifier. The anode of the first diode is connected between the lower bridge arm sampling resistor and the common ground. The cathode of the first diode and one end of the third resistor are connected to the non-inverting input terminal of the third operational amplifier, and the other end of the third resistor is connected to the common ground.

[0010] Based on the above, the first diode, the third resistor, and the third operational amplifier constitute the reverse connection circuit. When there is voltage at the DC_CK terminal, the positive and negative busbars are in reverse connection state, and the reverse connection circuit protects the detection circuit.

[0011] Furthermore, a first load resistor is provided between the positive terminal of the power supply and the ground terminal. One end of the first load resistor is connected to the positive terminal of the power supply and the other end is connected to the ground terminal. A third switch is provided between the other end of the first load resistor and the other end of the upper bridge arm sampling resistor. A second load resistor is provided between the negative terminal of the power supply and the ground terminal.

[0012] Based on the above, when the insulation detection circuit is not performing detection work and the third switch is turned off, the parameters of the detection circuit itself will not affect the overall insulation performance of the machine. At this time, the first load resistor and the second load resistor act as loads.

[0013] Furthermore, the first switch, the second switch, and the third switch are respectively connected to the first relay circuit, the second relay circuit, and the third relay circuit with the same structure. The first relay circuit includes a fourth resistor, a fifth resistor, a first transistor, a second diode, and the first switch. One end of the fourth resistor and one end of the fifth resistor are connected to the base of the first transistor. The other end of the fifth resistor and the emitter of the transistor are both connected to a common ground. The anode of the second diode is connected to the collector of the first transistor. The first switch and the second diode are connected in parallel.

[0014] To more clearly illustrate the above-mentioned features of this utility model and the objectives it aims to achieve, the present utility model will be further described below in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0015] Figure 1 This is a circuit diagram of the present invention.

[0016] Figure 2 : This is a circuit diagram of the first relay circuit, the second relay circuit, and the third relay circuit of this utility model;

[0017] Figure 3 : A partial circuit diagram of this utility model when the first switch, the second switch, and the third switch are closed;

[0018] Figure 4 This is a partial circuit diagram of the present invention when the first and third switches are closed and the second switch is opened.

[0019] Figure 5 This is a partial circuit diagram of the present invention when the second and third switches are closed and the first switch is opened. Detailed Implementation

[0020] like Figure 1 As shown, a bridge-arm insulation detection circuit includes an upper bridge-arm insulation sampling circuit, a lower bridge-arm insulation sampling circuit, and a reverse connection circuit. The upper bridge-arm insulation sampling circuit includes a first switch KA1, a first resistor R1, an upper bridge-arm sampling resistor Ra, and a first operational amplifier U1. One end of the first switch KA1 is connected to the positive terminal DC+ of the power supply, and the other end is connected to one end of the first resistor R1. One end of the upper bridge-arm sampling resistor Ra and the other end of the first resistor R1 are both connected to the non-inverting input terminal of the first operational amplifier U1. The other end of the upper bridge-arm sampling resistor Ra is connected to... The common ground GND; the lower bridge arm insulation sampling circuit includes a second switch KA2, a second resistor R2, a lower bridge arm sampling resistor Rb, and a second operational amplifier U2. One end of the second switch KA2 is connected to the negative terminal of the power supply DC-, and the other end is connected to one end of the second resistor R2. One end of the lower bridge arm sampling resistor Rb and the other end of the second resistor R2 are both connected to the non-inverting input terminal of the second operational amplifier U2. The other end of the lower bridge arm sampling resistor Rb is connected to the common ground GND. The reverse connection circuit is connected between the lower bridge arm sampling resistor Rb and the common ground GND.

[0021] The upper bridge arm insulation sampling circuit is used to collect the voltage of the upper bridge arm sampling resistor Ra, and the lower bridge arm insulation sampling circuit is used to collect the voltage of the lower bridge arm sampling resistor Rb. Based on the voltages of the upper and lower bridge arm sampling resistors Ra and Rb, combined with known quantities, the equivalent resistance values ​​of the positive and negative terminals to ground can be calculated. These values ​​are then compared with national standard insulation resistance values ​​to determine whether the insulation resistance is abnormal. The upper and lower bridge arm insulation sampling circuits are respectively equipped with a first operational amplifier U1 and a second operational amplifier U2. These amplifiers amplify the collected signals, improving the sensitivity and accuracy of the detection. The reverse connection circuit protects the detection equipment, preventing damage from reverse power connections and reducing maintenance costs.

[0022] Preferably, the reverse connection circuit includes a first diode D1, a third resistor R3, and a third operational amplifier U3. The anode of the first diode D1 is connected between the lower bridge arm sampling resistor Rb and the common ground GND. The cathode of the first diode D1 and one end of the third resistor R3 are connected to the non-inverting input terminal of the third operational amplifier U3, and the other end of the third resistor R3 is connected to the common ground GND. When there is voltage at the DC_CK terminal, the positive and negative buses are in a reverse connection state, and the reverse connection circuit protects the detection circuit.

[0023] Preferably, a first load resistor (Rx1) is provided between the positive terminal of the power supply (DC+) and the ground terminal (PE). One end of the first load resistor (Rx1) is connected to the positive terminal of the power supply (DC+), and the other end is connected to the ground terminal (PE). A third switch (KA3) is provided between the other end of the first load resistor (Rx1) and the other end of the upper bridge arm sampling resistor (Ra). A second load resistor (Rx2) is provided between the negative terminal of the power supply (DC-) and the ground terminal (PE). When the insulation detection circuit is not performing detection work, or when insulation detection is performed using external equipment, the third switch KA3 is disconnected. The parameters of the detection circuit itself will not affect the overall insulation performance of the device. At this time, the first load resistor Rx1 and the second load resistor Rx2 act as loads.

[0024] Furthermore, the first switch KA1, the second switch KA2, and the third switch KA3 are respectively connected to the first relay circuit U4, the second relay circuit U5, and the third relay circuit U6, which have the same structure. The first relay circuit U4 includes a fourth resistor R4, a fifth resistor R5, a first transistor Q1, a second diode D2, and the first switch KA1. One end of the fourth resistor R4 and one end of the fifth resistor R5 are connected to the base of the first transistor Q1. The other end of the fifth resistor R5 and the emitter of the first transistor Q1 are both connected to the common ground GND. The anode of the second diode D2 is connected to the collector of the first transistor Q1. The first switch KA1 and the second diode D2 are connected in parallel.

[0025] The specific implementation method of this embodiment is as follows:

[0026] First, simultaneously close the first switch KA1, the second switch KA2, and the third switch KA3. Measure the voltage of ADC+ as Up and the voltage of ADC- as Un. The circuit diagram at this point is as follows: Figure 3 As shown. The calculation formula is:

[0027] Formula①

[0028] The voltage U between the positive and negative busbars can be obtained using formula ①.

[0029] Next, simultaneously close the first switch KA1 and the third switch KA3, and open the second switch KA2. The voltage across ADC+ is measured to be Ua. The circuit diagram at this point is as follows: Figure 4 As shown. The calculation formula is:

[0030] Formula②

[0031] Rp is the equivalent resistance of the positive terminal to ground and Rn is the equivalent resistance of the negative terminal to ground.

[0032] Finally, simultaneously close the second switch KA2 and the third switch KA3, and open the first switch KA1. The voltage of ADC- at this point is measured to be Ub. The circuit diagram at this time is as follows. Figure 5 As shown. The calculation formula is:

[0033] Formula③

[0034] Combining the above formulas, we can obtain the following:

[0035]

[0036]

[0037] Finally, the equivalent resistance Rp of the positive terminal to ground and the equivalent resistance Rn of the negative terminal to ground are obtained. These values ​​are then compared with the national standard insulation resistance to determine whether the insulation resistance of the charging module is normal. The smaller the corresponding circuit parameters, the more accurate the detection will be when the equivalent resistance Rp of the positive terminal to ground and the equivalent resistance Rn of the negative terminal to ground are.

[0038] The above description is only the optimal solution embodiment of this utility model and is not intended to limit this utility model. Various modifications or substitutions made by those skilled in the art to this utility model without departing from the essence and protection scope of this utility model should also be within the protection scope of this utility model.

Claims

1. A bridge-arm type insulation detection circuit, characterized in that: This includes the upper bridge arm insulation sampling circuit, the lower bridge arm insulation sampling circuit, and the reverse connection circuit; The upper bridge arm insulation sampling circuit includes a first switch (KA1), a first resistor (R1), an upper bridge arm sampling resistor (Ra), and a first operational amplifier (U1). One end of the first switch (KA1) is connected to the positive terminal of the power supply (DC+), and the other end is connected to one end of the first resistor (R1). One end of the upper bridge arm sampling resistor (Ra) and the other end of the first resistor (R1) are both connected to the non-inverting input terminal of the first operational amplifier (U1). The other end of the upper bridge arm sampling resistor (Ra) is connected to the common ground (GND). The lower bridge arm insulation sampling circuit includes a second switch (KA2), a second resistor (R2), a lower bridge arm sampling resistor (Rb), and a second operational amplifier (U2). One end of the second switch (KA2) is connected to the negative terminal of the power supply (DC-), and the other end is connected to one end of the second resistor (R2). One end of the lower bridge arm sampling resistor (Rb) and the other end of the second resistor (R2) are both connected to the non-inverting input terminal of the second operational amplifier (U2). The other end of the lower bridge arm sampling resistor (Rb) is connected to the common ground (GND). The reverse connection circuit is connected between the lower bridge arm sampling resistor (Rb) and the common ground (GND).

2. The bridge-arm type insulation detection circuit according to claim 1, characterized in that: The reverse connection circuit includes a first diode (D1), a third resistor (R3), and a third operational amplifier (U3). The anode of the first diode (D1) is connected between the lower bridge arm sampling resistor (Rb) and the common ground (GND). The cathode of the first diode (D1) and one end of the third resistor (R3) are connected to the non-inverting input of the third operational amplifier (U3), and the other end of the third resistor (R3) is connected to the common ground (GND).

3. The bridge-arm type insulation detection circuit according to claim 1, characterized in that: A first load resistor (Rx1) is provided between the positive terminal (DC+) of the power supply and the ground terminal (PE). One end of the first load resistor (Rx1) is connected to the positive terminal (DC+) of the power supply and the other end is connected to the ground terminal (PE). A third switch (KA3) is provided between the other end of the first load resistor (Rx1) and the other end of the upper bridge arm sampling resistor (Ra). A second load resistor (Rx2) is provided between the negative terminal (DC-) of the power supply and the ground terminal (PE).

4. The bridge-arm type insulation detection circuit according to claim 1, characterized in that: The first switch (KA1), the second switch (KA2), and the third switch (KA3) are respectively connected to the first relay circuit (U4), the second relay circuit (U5), and the third relay circuit (U6) with the same structure. The first relay circuit (U4) includes a fourth resistor (R4), a fifth resistor (R5), a first transistor (Q1), a second diode (D2), and the first switch (KA1). One end of the fourth resistor (R4) and one end of the fifth resistor (R5) are connected to the base of the first transistor (Q1). The other end of the fifth resistor (R5) and the emitter of the first transistor (Q1) are both connected to the common ground (GND). The anode of the second diode (D2) is connected to the collector of the first transistor (Q1). The first switch (KA1) and the second diode (D2) are connected in parallel.

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