Insulation resistance real-time detection method based on digital realization

Abstract

The invention belongs to the technical field of digital switching power supplies, and particularly relates to an insulation resistance real-time detection method based on digital implementation. The method comprises an insulation detection circuit, the circuit comprises resistor strings, a first branch 5V power supply, a switch optocoupler Q1, switch tube strings G1 and G2, response driving resistors R6 and R7 and the like, and further comprises a second branch 48V power supply, VZ and other elements, a sampling point 1 of R5 voltage is obtained through a single-chip microcomputer, a sampling point 2 of input positive P and a sampling point 3 of input negative N are obtained, and the sampling point 1 and the sampling point 3 of the input positive P and the input negative N are connected in series. An optocoupler switch is controlled in cooperation with algorithm operation; according to the method, the low-voltage power supply is matched with the low-voltage period, and the on-off of the MOS tube is controlled by combining the on-off of the optocoupler to perform circuit combination, so that the detection of the insulation resistance is realized, and the detection cost of the insulation resistance is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of digital switching power supplies, and in particular relates to a real-time detection method for insulation resistance based on digital implementation. Background Art

[0002] Insulation resistance is the most basic insulation indicator for electrical equipment and electrical circuits. Insulation detection of battery stacks and batteries in new energy power sources is a guarantee for safe operation. Insulation resistance values ​​are generally used to reflect the insulation resistance of the positive and negative electrodes of the battery and battery stack to the ground. Insulation circuits or insulation detection instruments are used to detect the insulation resistance of batteries in related technologies. The insulation circuit can detect the insulation of the positive electrode of the battery to the ground and the negative electrode of the battery to the ground by closing and opening the switch on the insulation circuit. The insulation detection of batteries and battery stacks in related technologies usually takes a long time, which leads to a longer battery power supply response time for electrical equipment; detection instruments can generally only be used for detection before the equipment is operated. Real-time detection using instruments during the operation of the equipment is not suitable for equipment that operates stably for a long time, such as solar energy conversion power supplies, front fuel power supply equipment, and vehicle-mounted power supply equipment. Summary of the invention

[0003] In view of the above problems existing in the prior art, the object of the present invention is to provide a real-time detection method of insulation resistance based on digital implementation to meet the demand of insulation resistance detection and reduce the cost of insulation resistance detection.

[0004] In order to solve the above problems, the technical solution adopted by the present invention is as follows:

[0005] A real-time detection method for insulation resistance based on digital implementation, the method comprising an insulation detection circuit, the insulation detection circuit comprising a first resistor R1 and a second resistor R2 connected in parallel, the other end of the first resistor R1 is connected to an input positive P, and the other end of the second resistor R2 is connected to an input negative N;

[0006] The input positive P is connected to Rspm and Rspn in series, and the other end of Rspn is grounded;

[0007] The input negative N is connected to Rsnm and Rsnn in series, and the other end of Rsnn is grounded;

[0008] A third resistor R3 is connected to the connection point between the first resistor R1 and the second resistor R2, and the other end of the third resistor R3 is connected to a power source V1; a fourth resistor R4 is also connected to the connection point between the first resistor R1 and the second resistor R2, and the fourth resistor R4 is connected in series with a fifth resistor R5;

[0009] The connection point between the input positive P and the first resistor R1 and the Rspm is connected to a resistor Rp, and the connection point between the input negative N and the second resistor R2 and the Rsnm is connected to a resistor Rn. The Rp and the Rn are connected in series to obtain a PE point, and the PE point is connected to a first switch tube G1 and a second switch tube G2. The first switch tube G1 and the second switch tube G2 are complementary controlled, and the PE point is also connected to the positive electrode of the power supply V2;

[0010] The driving of the first switch tube G1 and the second switch tube G2 is controlled by an optical coupler Q1, one end of the optical coupler Q1 is grounded, and the other end is connected to JY_AC;

[0011] When the optical coupler Q1 is turned on, the second switch tube G2 is turned on, and the PE is grounded;

[0012] When the optical coupler Q1 is disconnected, the first switch tube G1 is turned on, and the PE is grounded through the power supply V2;

[0013] The method comprises the following steps:

[0014] (1) obtaining, by calculation and processing by a single chip computer, a voltage at a connection point between the first resistor R1 and the second resistor R2, and a voltage between the positive input P and the negative input N and ground;

[0015] (2) Control the logic flow of insulation monitoring with timing, control the JY_AC to output a high level at the first timing, and ground the PE. At this time, store the current voltage Vo1 at the connection point of the first resistor R1 and the second resistor R2, the voltage Vp1 of the positive input P, ​​and the voltage Vn1 of the negative input N;

[0016] (3) At the second timing, the JY_AC is controlled to output a low level, the PE is connected to the power supply V2, and the current voltage Vo2 at the connection point of the first resistor R1 and the second resistor R2, the voltage Vp2 of the positive input P, ​​and the voltage Vn2 of the negative input N are stored again;

[0017] (4) Based on the voltages recorded twice, the positive insulation resistance Rp and the negative insulation resistance Rn are calculated by using the KCL equation.

[0018] Furthermore, when the PE is grounded, the KCL equation of the PE point is:

[0019]

[0020] make

[0021] but

[0022] Furthermore, when the PE is connected to the power supply V2, the KCL equation at the PE point is:

[0023]

[0024]

[0025] make

[0026] but

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The method realizes the detection of insulation resistance by coordinating the low-voltage power supply with the low-voltage period and combining the switch of the optocoupler to control the switch of the MOS tube to perform circuit combination, thereby reducing the cost of insulation resistance detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of the circuit structure of the insulation detection circuit of the present invention;

[0030] Figure 2 is a schematic diagram of the equivalent circuit structure of each power supply at sampling point 1 in its voltage division;

[0031] Figure 3 is a schematic diagram of an equivalent circuit structure when the first switch tube G1 is closed;

[0032] Figure 4 is a schematic diagram of an equivalent circuit structure when the second switch tube G2 is closed;

[0033] Figure 5 Schematic diagram of the steps of this method. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific embodiments.

[0035] The real-time detection method of insulation resistance based on digital realization described in the present invention firstly comprises a specially designed insulation detection circuit.

[0036] like Figure 1 As shown, the insulation detection circuit comprises a first resistor R1 and a second resistor R2 connected in parallel, the other end of the first resistor R1 is connected to an input positive P, and the other end of the second resistor R2 is connected to an input negative N;

[0037] The input positive P is connected to Rspm and Rspn in series, and the other end of Rspn is grounded;

[0038] The input negative N is connected to Rsnm and Rsnn in series, and the other end of Rsnn is grounded;

[0039] The connection point of the first resistor R1 and the second resistor R2 is connected to a third resistor R3, the other end of the third resistor R3 is connected to a power supply V1 (a 5V power supply is used in this embodiment), and the negative end of the power supply V1 is grounded. The connection point of the first resistor R1 and the second resistor R2 is also connected to a fourth resistor R4, and the fourth resistor R4 is connected in series with a fifth resistor R5. The other end of the fifth resistor R5 is grounded.

[0040] The connection point between the positive input P and the first resistor R1 and Rspm is connected to the resistor Rp, and the connection point between the negative input N and the second resistor R2 and Rsnm is connected to the resistor Rn. Rp and Rn are connected in series to obtain a PE point. The PE point is connected to the first switch tube G1 and the second switch tube G2. The first switch tube G1 and the second switch tube G2 are controlled complementary. The PE point is also connected to the positive electrode of the power supply V2 (a 48V power supply is used in this embodiment), and the negative electrode of the power supply V2 is grounded.

[0041] The first switch tube G1 and the second switch tube G2 are driven by the optocoupler Q1, one end of the optocoupler Q1 is grounded, and the other end is connected to JY_AC. The circuit structure also includes a drive control circuit VZ and a sixth resistor R6 connected to the first switch tube G1, a seventh resistor R7 connected to the second switch tube G2, and an eighth resistor R8 connected to the optocoupler Q1.

[0042] When the optocoupler Q1 is turned on, the second switch tube G2 is turned on, and PE is grounded. Figure 3 The schematic diagram of the equivalent circuit structure when the first switch tube G1 is closed is shown;

[0043] When the optocoupler Q1 is disconnected, the first switch tube G1 is turned on, and PE is grounded through the power supply V2. Figure 4 The figure shows the schematic diagram of the equivalent circuit structure when the second switch tube G2 is closed.

[0044] Then test, such as Figure 5 As shown, the detection method comprises the following steps:

[0045] (1) The insulation resistance is calculated by a single-chip microcomputer. The single-chip microcomputer processing includes: ADC sampling and conversion processing of sampling point 1, sampling point 2, and sampling point 3, the logic control process of insulation detection, and the algorithm processing of insulation calculation. Figure 1 The locations of the three sampling points are shown in Figure 2The equivalent circuit structure diagram of each power supply in its voltage division for sampling point 1 is shown. Therefore, the voltage of each sampling point can be collected and converted into the voltage of the connection point of the first resistor R1 and the second resistor R2, and the voltage of the input positive P and the input negative N to the ground through the single chip calculation and processing, in the 20us interrupt service;

[0046] (2) The single-chip microcomputer controls the logic flow of insulation monitoring with a 10ms timing. In the first 10ms timing, JY_AC is controlled to output a high level and PE is grounded. At this time, the current voltage Vo1 at the connection point of the first resistor R1 and the second resistor R2, the voltage Vp1 of the positive input P, ​​and the voltage Vn1 of the negative input N are stored;

[0047] (3) In the second 10ms timing control, JY_AC outputs a low level, the PE is connected to the power supply V2, and the current voltage Vo2 at the connection point of the first resistor R1 and the second resistor R2, the voltage Vp2 of the positive input P, ​​and the voltage Vn2 of the negative input N are stored again;

[0048] (4) Based on the voltages recorded twice, the positive insulation resistance Rp and the negative insulation resistance Rn are calculated by using the KCL equation.

[0049] When PE is grounded, the KCL equation at the PE point is:

[0050]

[0051] make

[0052] but

[0053] When PE is connected to power supply V2, the KCL equation at PE is:

[0054]

[0055] make

[0056] but

Claims

1. A real-time detection method for insulation resistance based on digital implementation, characterized in that: The method includes an insulation detection circuit, wherein the insulation detection circuit includes a first resistor R1 and a second resistor R2 connected in parallel, the other end of the first resistor R1 is connected to an input positive P, and the other end of the second resistor R2 is connected to an input negative N; The input positive P is connected to Rspm and Rspn in series, and the other end of Rspn is grounded; The input negative N is connected to Rsnm and Rsnn in series, and the other end of Rsnn is grounded; A third resistor R3 is connected to the connection point between the first resistor R1 and the second resistor R2, and the other end of the third resistor R3 is connected to a power source V1; a fourth resistor R4 is also connected to the connection point between the first resistor R1 and the second resistor R2, and the fourth resistor R4 is connected in series with a fifth resistor R5; The connection point between the input positive P and the first resistor R1 and the Rspm is connected to a resistor Rp, and the connection point between the input negative N and the second resistor R2 and the Rsnm is connected to a resistor Rn. The Rp and the Rn are connected in series to obtain a PE point, and the PE point is connected to a first switch tube G1 and a second switch tube G2. The first switch tube G1 and the second switch tube G2 are complementarily controlled, and the PE point is also connected to the positive electrode of the power supply V2; The driving of the first switch tube G1 and the second switch tube G2 is controlled by an optical coupler Q1, one end of the optical coupler Q1 is grounded, and the other end is connected to JY_AC; When the optical coupler Q1 is turned on, the second switch tube G2 is turned on, and the PE is grounded; When the optical coupler Q1 is disconnected, the first switch tube G1 is turned on, and the PE is grounded through the power supply V2; The method comprises the following steps: (1) obtaining, by calculation and processing by a single chip computer, a voltage at a connection point between the first resistor R1 and the second resistor R2, and a voltage between the positive input P and the negative input N and ground; (2) Control the logic flow of insulation monitoring with timing, control the JY_AC to output a high level at the first timing, and ground the PE. At this time, store the current voltage Vo1 at the connection point of the first resistor R1 and the second resistor R2, the voltage Vp1 of the positive input P, ​​and the voltage Vn1 of the negative input N; (3) At the second timing, the JY_AC is controlled to output a low level, the PE is connected to the power supply V2, and the current voltage Vo2 at the connection point of the first resistor R1 and the second resistor R2, the voltage Vp2 of the positive input P, ​​and the voltage Vn2 of the negative input N are stored again; (4) Based on the voltages recorded twice, the positive insulation resistance Rp and the negative insulation resistance Rn are calculated by using the KCL equation.

2. The real-time detection method for insulation resistance based on digital implementation according to claim 1 is characterized in that: When the PE is grounded, the KCL equation at the PE point is: make but 3. The real-time detection method of insulation resistance based on digital implementation according to claim 1 is characterized in that: When the PE is connected to the power supply V2, the KCL equation of the PE point is: make but

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