A whole vehicle insulation detection system and method

Abstract

The application relates to the field of new energy automobile high-voltage safety and battery management, and discloses a whole vehicle insulation detection system and method, the system comprises: a control module, which is used for starting a pilot heating mode and switching the switch combination state of an insulation detection circuit; a voltage acquisition module, which is used for acquiring the voltage of a battery negative pole to a vehicle body ground, the high-voltage bus voltage and the voltage of a battery pack positive pole to the vehicle body ground under each switch combination state; an insulation resistance calculation module, which is used for constructing an equation group based on the voltage acquisition data to solve the whole vehicle side positive pole to ground insulation resistance and the whole vehicle side negative pole to ground insulation resistance; and a warning module, which is used for judging whether the whole vehicle high-voltage exists an insulation fault based on the whole vehicle side positive pole and negative pole to ground insulation resistance, and taking preventive measures; the voltage values under each switch combination state in the insulation detection circuit are acquired, and the whole vehicle side positive pole to ground insulation resistance and the whole vehicle side negative pole to ground insulation resistance are derived and calculated.

Description

Technical Field

[0001] This invention belongs to the field of high-voltage safety and battery management technology for new energy vehicles, and specifically relates to a whole vehicle insulation detection system and method. Background Technology

[0002] With the rapid development of new energy vehicle technology, charging performance in low-temperature environments has become one of the core pain points in user experience. Lithium batteries experience a significant decrease in charging acceptance at low temperatures; direct high-current charging can lead to lithium plating within the cells, severely impacting battery life and safety. To address this, the industry commonly employs pilot heating technology: after the vehicle is plugged in, the external charging station's power is used to drive the onboard heating device (such as a PTC heater) to raise the battery pack to its optimal charging temperature range before initiating formal charging. This significantly shortens charging time in low temperatures.

[0003] Currently, the bridge method is commonly used for high-voltage insulation testing of vehicles. The testing circuit is integrated into the battery management system (BMS). It relies on the closure of all the main positive and main negative relays of the battery pack to form a complete circuit between the battery pack and the vehicle's high-voltage bus. By connecting bridge arm resistors with known resistance values ​​between the high-voltage positive and negative terminals and the vehicle ground, the voltage to ground under different switching states is collected, and the insulation resistance between the positive and negative terminals to ground is solved by solving simultaneous equations.

[0004] Therefore, there is an urgent need for a technical solution that can accurately calculate the insulation resistance of the whole vehicle in the pilot heating mode when the main positive relay is disconnected, based on the existing BMS hardware architecture and without adding hardware costs. Summary of the Invention

[0005] To address the above problems, the present invention provides a whole vehicle insulation testing system and method.

[0006] The first aspect of this invention provides a vehicle insulation testing system, comprising: The control module is used to start the pilot heating mode and switch the switching combination state of the insulation detection circuit; The voltage acquisition module is used to acquire the voltage of the battery negative terminal to the vehicle ground, the high voltage bus voltage, and the voltage of the battery pack positive terminal to the vehicle ground under each switch combination state. The insulation resistance calculation module is used to construct a set of equations based on voltage acquisition data to solve for the insulation resistance between the positive terminal and ground on the vehicle side and the insulation resistance between the negative terminal and ground on the vehicle side. The early warning module is used to determine whether there is an insulation fault in the high voltage of the vehicle based on the insulation resistance values ​​of the positive and negative terminals to ground on the vehicle side, and to take preventive measures.

[0007] In some embodiments, the insulation detection circuit includes a positive side branch and a negative side branch; the positive side branch includes a series-connected positive normally-continuous bridge arm resistor and a positive parallel bridge arm resistor, and the insulation positive parallel switch is connected in parallel with the positive parallel bridge arm resistor; the negative side branch includes a series-connected negative normally-continuous bridge arm resistor and a negative parallel bridge arm resistor, and the insulation negative parallel switch is connected in parallel with the negative parallel bridge arm resistor.

[0008] In some embodiments, the acquisition of the voltage of the battery negative terminal to the vehicle ground, the high-voltage bus voltage, and the voltage of the battery pack positive terminal to the vehicle ground under each switching combination state includes acquiring the voltages under the following three switching states: State 1: The insulated positive parallel switch is closed, and the insulated negative parallel switch is open; State 2: The insulated positive parallel switch is open, and the insulated negative parallel switch is closed; State 3: The insulated positive parallel switch is open, and the insulated negative parallel switch is open.

[0009] In some embodiments, three switch combination states are switched sequentially, with a 10-20ms wait after each switch, and the voltage is collected 5-8 times for each switch combination state and the average value is taken.

[0010] In some embodiments, determining whether there is an insulation fault in the high voltage circuit of the vehicle and taking preventive measures includes: taking the smaller value between the insulation resistance value of the positive terminal to ground and the insulation resistance value of the negative terminal to ground on the vehicle side as the insulation resistance value of the high voltage circuit of the vehicle, comparing it with a preset threshold, and if it is lower than the preset threshold, triggering an insulation fault in the vehicle, stopping the pilot heating, and disconnecting the DC positive relay and the DC negative relay.

[0011] In some embodiments, the voltage of the vehicle's positive terminal to the vehicle ground is the sum of the voltage of the battery pack's negative terminal to the vehicle ground and the voltage of the high-voltage bus.

[0012] In some embodiments, Cramer's rule is used to solve the system of equations.

[0013] A second aspect of the present invention provides a method for testing the insulation of a whole vehicle, applied to a vehicle insulation testing system described in the first aspect of the present invention, the method comprising the following steps: Start pilot heating mode; Collect the voltage of the battery negative terminal to the vehicle ground, the high-voltage bus voltage, and the voltage of the battery pack positive terminal to the vehicle ground under each switch combination state. Based on voltage acquisition data, a system of equations was constructed to solve for the insulation resistance between the positive terminal and ground on the vehicle side and the insulation resistance between the negative terminal and ground on the vehicle side. Based on the insulation resistance values ​​of the positive and negative terminals of the vehicle to ground, determine whether there is an insulation fault in the high voltage of the vehicle and take preventive measures.

[0014] In some embodiments, activating the pilot heating mode includes: After the vehicle plugs in the charging gun, it completes the charging handshake and enters the pilot heating preparation state. The main negative relay of the control battery pack is kept closed and the main positive relay is opened, so that the negative terminal of the battery pack is connected to the high voltage negative bus of the vehicle at the same potential, and the positive terminal of the battery pack is electrically disconnected from the high voltage positive bus of the vehicle. Close the DC positive relay and DC negative relay to connect the high-voltage power supply circuit between the external charging pile and the vehicle, and start the pilot heater.

[0015] In some embodiments, the step of constructing a system of equations based on voltage acquisition data to solve for the insulation resistance between the positive terminal and ground on the vehicle side and the insulation resistance between the negative terminal and ground on the vehicle side includes: The voltage of the vehicle's positive side to the vehicle ground is calculated based on the voltage of the negative terminal of the battery pack to the vehicle ground and the voltage of the high-voltage bus under each switch combination state. Based on the voltage acquisition data and the voltage between the positive terminal of the vehicle and the vehicle body ground, a system of equations is constructed; The system of equations was solved using Cramer's rule to obtain the insulation resistance values ​​of the positive terminal to ground and the negative terminal to ground on the vehicle side.

[0016] The beneficial effects of this invention are: (1) Based on the insulation detection circuit of the existing battery management system, the present invention obtains the insulation resistance value of the positive terminal to ground and the insulation resistance value of the negative terminal to ground of the whole vehicle by collecting the voltage value of each switch combination state in the insulation detection circuit, and determines whether the whole vehicle has an insulation fault based on the obtained insulation resistance value. This realizes the calculation of the insulation resistance value of the whole vehicle without closing the battery pack and the high voltage circuit of the whole vehicle in the pilot heating mode.

[0017] (2) The insulation detection of the present invention is based on the vehicle BMS and does not rely on the insulation detection function of the charging pile. It is applicable to both the new national standard and the old national standard charging piles, which greatly improves the scenario adaptability and universality of the pilot heating function.

[0018] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a vehicle insulation testing system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the equivalent circuit of the vehicle's high-voltage circuit under pilot heating mode provided in an embodiment of the present invention; Figure 3 This is a schematic flowchart of a whole vehicle insulation testing method provided in an embodiment of the present invention.

[0021] In the diagram, 1. External charging station; 2. DC positive relay; 3. Main positive relay; 4. DC negative relay; 5. Main negative relay; R p Insulation resistance between the positive terminal and ground of the entire vehicle; R n 1. Insulation resistance of the negative terminal to ground on the whole vehicle side; R pp , Positive parallel bridge arm resistor; R bp 1. Insulation resistance of the positive terminal of the battery pack; R np Negative parallel bridge arm resistor; R ps , Positive normally open bridge arm resistance; R ns The negative terminal is the normally open bridge arm resistor; V p The voltage of the vehicle's positive terminal relative to the vehicle body ground; V c Voltage of the battery pack positive terminal to the vehicle ground: V n The voltage between the negative terminal of the battery pack and the vehicle ground; V bus High-voltage bus voltage; I p The positive current of the vehicle to ground; I n The current from the negative terminal of the vehicle to ground; I c Battery pack positive terminal to vehicle ground current; PE, vehicle ground; K s Insulation grounding switch; K p Insulated positive parallel switch; K n Insulated negative pole parallel switch. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that the terms "first," "second," etc., used in this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein.

[0024] With the rapid development of new energy vehicle technology, charging performance in low-temperature environments has become one of the core pain points in user experience. Lithium batteries experience a significant decrease in charging acceptance at low temperatures; direct high-current charging can lead to lithium plating within the cells, severely impacting battery life and safety. To address this, the industry commonly employs pilot heating technology: after the vehicle is plugged in, the external charging station's power is used to drive the onboard heating device (such as a PTC heater) to raise the battery pack to its optimal charging temperature range before initiating formal charging. This significantly shortens charging time in low temperatures.

[0025] Currently, the bridge method is commonly used for high-voltage insulation testing of vehicles. The testing circuit is integrated into the battery management system (BMS). It relies on the closure of all the main positive and main negative relays of the battery pack to form a complete circuit between the battery pack and the vehicle's high-voltage bus. By connecting bridge arm resistors with known resistance values ​​between the high-voltage positive and negative terminals and the vehicle ground, the voltage to ground under different switching states is collected, and the insulation resistance between the positive and negative terminals to ground is solved by solving simultaneous equations.

[0026] To address the problems of existing technologies, this invention provides a vehicle insulation detection system and method. Under the condition that the main positive relay of the battery pack is not closed and only the main negative relay is closed, based on the existing BMS insulation detection circuit hardware, the system obtains the insulation resistance values ​​of the positive and negative terminals of the vehicle side to ground by solving a system of three switching states and a ternary equation system. This eliminates the high-voltage safety blind spot in the pilot heating condition and is compatible with both new and old national standard charging piles. The solution has low implementation cost.

[0027] Figure 1 This is a schematic diagram of a vehicle insulation detection system provided in an embodiment of the present invention, as shown below. Figure 1 As shown, a vehicle insulation detection system includes: a control module 110, a voltage acquisition module 120, an insulation resistance calculation module 130, and an early warning module 140.

[0028] The control module 110 is used to start the pilot heating mode and switch the switching combination state of the insulation detection circuit. The voltage acquisition module 120 is used to acquire the voltage V between the negative terminal of the battery pack and the vehicle ground under each switch combination state. n High voltage bus voltage V bus And the voltage V between the positive terminal of the battery pack and the vehicle ground c ; The insulation resistance calculation module 130 is used to construct a set of equations based on voltage acquisition data to solve for the insulation resistance value of the positive terminal to ground and the insulation resistance value of the negative terminal to ground on the vehicle side. The early warning module 140 is used to determine whether there is an insulation fault in the high voltage of the vehicle based on the insulation resistance values ​​of the positive and negative terminals to ground on the vehicle side, and to take preventive measures.

[0029] The pilot heating mode refers to the process where, after the vehicle is plugged in, the power from the external charging pile 1 is used to drive the on-board heating device (such as a PTC heater) to heat the battery pack to the optimal charging temperature range before starting formal charging.

[0030] Figure 2 This is a schematic diagram of the equivalent circuit of the vehicle's high-voltage circuit in pilot heating mode. Specifically, for example... Figure 2 As shown, the pilot heating mode startup includes: after the vehicle plugs in the charging gun, a charging handshake is completed, and the vehicle enters the pilot heating preparation state; the main negative relay 5 of the battery pack is kept closed and the main positive relay 3 is opened, so that the negative terminal of the battery pack is connected to the high voltage negative bus of the vehicle at the same potential, and the positive terminal of the battery pack is electrically disconnected from the high voltage positive bus of the vehicle; the DC positive relay 2 and the DC negative relay 4 are closed to connect the high voltage power supply circuit between the charging pile 1 and the vehicle, and the pilot heating is started.

[0031] Specifically, the insulation detection circuit is installed in the battery management system.

[0032] The insulation detection circuit includes a positive side branch and a negative side branch; the positive side branch includes a series-connected positive normally-continuous bridge arm resistor. Parallel bridge arm resistor with positive terminal The insulated positive parallel switch The bridge arm resistor connected in parallel with the positive electrode Parallel connection; the negative side branch includes a series-connected negative bridge arm resistor. Bridge arm resistor connected in parallel with the negative terminal The insulated negative pole parallel switch The bridge arm resistor connected in parallel with the negative terminal in parallel.

[0033] The insulation detection circuit mentioned above has an insulation resistance R with the positive terminal of the battery pack. bp An insulation grounding switch K is installed between them. s。

[0034] In this embodiment of the invention, the positive electrode normally open bridge arm resistor... Positive parallel bridge arm resistor A parallel switch with insulated positive poles Controls on / off state; negative terminal is normally open, bridge arm resistor Negative parallel bridge arm resistor A switch connected in parallel with an insulated negative pole Control the on / off state.

[0035] Specifically, the voltage V between the negative terminal of the battery and the vehicle ground is collected under each switching state. n High voltage bus voltage V bus And the voltage V between the positive terminal of the battery pack and the vehicle ground c This includes collecting voltage data under the following three switching states: State 1: Insulated positive parallel switch K p Closed, insulated negative parallel switch K n disconnect; State 2: Insulated positive parallel switch K p Disconnect, insulated negative parallel switch K n closure; State 3: Insulated positive parallel switch K p Disconnect, insulated negative parallel switch K n disconnect; The process involves sequentially switching three switch combinations, waiting 10-20ms after each switch to allow the circuit to reach a steady state, and collecting voltage data 5-8 times for each switch combination and taking the average value to obtain three sets of sampling data.

[0036] Based on Kirchhoff's Current Law (KCL), with the vehicle body ground PE as the common node, and the algebraic sum of the currents to ground of all high-voltage branches being 0, the following current balance formula can be obtained:

[0037] Among them, I p For the positive side of the vehicle connected to ground, I n For the vehicle's negative side to ground current, I c This refers to the current from the positive terminal of the battery pack to the vehicle ground.

[0038] Based on the above current balance formula and the voltage under the three switching states, the following three sets of equations are obtained:

[0039]

[0040]

[0041] In the formula, V p1 V p2 V P3 These represent the voltage (V) between the positive terminal of the vehicle and the vehicle ground under three different switching conditions. n1 V n2 V n3 These represent the voltage (V) between the negative terminal of the battery pack and the vehicle ground in three different switching states. c1 V c2 V c3 These represent the voltage of the battery pack positive terminal to the vehicle ground under three different switching states; in, , , V bus This is the high-voltage bus voltage, obtained through the charging station.

[0042] Cramer's rule is used to solve the system of equations.

[0043] make:

[0044] Introducing the first equivalent current Second equivalent current and the third equivalent current :

[0045]

[0046]

[0047] The simplified system of equations is as follows:

[0048]

[0049]

[0050] Solve , :

[0051]

[0052]

[0053]

[0054] Where D is the coefficient determinant, D p D n D c To replace the determinant.

[0055] The insulation resistance R between the positive terminal and ground of the entire vehicle was obtained. p The insulation resistance R of the negative terminal to ground on the whole vehicle side n : ,

[0056] ,

[0057] Specifically, the determination of whether there is an insulation fault in the vehicle's high voltage circuit and the implementation of preventive measures include: taking the smaller of the insulation resistance values ​​between the positive and negative terminals of the vehicle side and ground as the insulation resistance value of the vehicle's high voltage circuit, comparing it with a preset threshold, and if the value is lower than the preset threshold, triggering a vehicle insulation fault, stopping pilot heating, and disconnecting the DC positive and DC negative relays.

[0058] The preset threshold can be 100 ohms / V according to national standards.

[0059] This invention is based entirely on existing BMS insulation detection circuits, requiring no additional sampling circuits or hardware modules. Functionality is achieved solely through software algorithm optimization, resulting in low implementation costs. Even with the main positive relay disconnected and the battery pack positive terminal disconnected from the high-voltage circuit, it can still accurately calculate the insulation resistance of the vehicle's high-voltage positive and negative terminals to ground, enabling insulation monitoring throughout the pilot heating process and mitigating the risk of high-voltage leakage. It eliminates reliance on the insulation detection function of the charging pile; regardless of whether it's a new or old national standard charging pile, the vehicle can autonomously complete the overall vehicle insulation detection, significantly improving the scenario adaptability of the pilot heating function. It supports insulation detection even with the main positive relay disconnected, preventing passive low-temperature charging of the battery pack during pilot heating and balancing high-voltage safety with cell lifespan.

[0060] This invention also provides an insulation detection method in pilot heating mode, which is applied to an insulation detection system in pilot heating mode described in the above embodiments.

[0061] like Figure 3 As shown, an insulation detection method in pilot heating mode includes the following steps: S1. Start pilot heating mode; S2. Collect the voltage of the battery negative terminal to the vehicle ground, the high-voltage bus voltage, and the voltage of the battery pack positive terminal to the vehicle ground under each switch combination state. S3. Based on the voltage acquisition data, construct a system of equations to solve for the insulation resistance between the positive terminal and the ground on the vehicle side and the insulation resistance between the negative terminal and the ground on the vehicle side. S4. Based on the insulation resistance values ​​of the positive and negative terminals of the vehicle to ground, determine whether there is an insulation fault in the high voltage of the vehicle and take preventive measures. Specifically, the activation of the pilot heating mode includes: After the vehicle plugs in the charging gun, it completes the charging handshake and enters the pilot heating preparation state. The main negative relay of the control battery pack is kept closed and the main positive relay is opened, so that the negative terminal of the battery pack is connected to the high voltage negative bus of the vehicle at the same potential, and the positive terminal of the battery pack is electrically disconnected from the high voltage positive bus of the vehicle. Close the DC positive relay and DC negative relay to connect the high-voltage power supply circuit between the external charging pile and the vehicle, and start the pilot heater.

[0062] Specifically, the step of constructing a system of equations based on voltage acquisition data to solve for the insulation resistance between the positive terminal and ground on the vehicle side and the insulation resistance between the negative terminal and ground on the vehicle side includes: The voltage of the vehicle's positive side to the vehicle ground is calculated based on the voltage of the negative terminal of the battery pack to the vehicle ground and the voltage of the high-voltage bus under each switch combination state. Based on the voltage acquisition data and the voltage between the positive terminal of the vehicle and the vehicle body ground, a system of equations is constructed; The system of equations was solved using Cramer's rule to obtain the insulation resistance values ​​of the positive terminal to ground and the negative terminal to ground on the vehicle side.

[0063] This invention is based on the insulation detection circuit of the existing battery management system. By collecting the voltage values ​​of each switch combination state, the insulation resistance value of the positive terminal to ground and the insulation resistance value of the negative terminal to ground on the vehicle side are derived and calculated. Based on the obtained insulation resistance value, it is determined whether there is an insulation fault in the vehicle. This realizes the calculation of the insulation resistance value of the vehicle without closing the battery pack and the high voltage circuit of the vehicle in the pilot heating mode.

[0064] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A vehicle insulation testing system, characterized in that, include: The control module is used to start the pilot heating mode and switch the switching combination state of the insulation detection circuit; The voltage acquisition module is used to acquire the voltage of the battery negative terminal to the vehicle ground, the high voltage bus voltage, and the voltage of the battery pack positive terminal to the vehicle ground under each switch combination state. The insulation resistance calculation module is used to construct a set of equations based on voltage acquisition data to solve for the insulation resistance between the positive terminal and ground on the vehicle side and the insulation resistance between the negative terminal and ground on the vehicle side. The early warning module is used to determine whether there is an insulation fault in the high voltage of the vehicle based on the insulation resistance values ​​of the positive and negative terminals to ground on the vehicle side, and to take preventive measures.

2. The vehicle insulation testing system according to claim 1, characterized in that, The insulation detection circuit includes a positive side branch and a negative side branch; the positive side branch includes a series-connected positive normally-continuous bridge arm resistor and a positive parallel bridge arm resistor, and the insulation positive parallel switch is connected in parallel with the positive parallel bridge arm resistor; the negative side branch includes a series-connected negative normally-continuous bridge arm resistor and a negative parallel bridge arm resistor, and the insulation negative parallel switch is connected in parallel with the negative parallel bridge arm resistor.

3. The vehicle insulation testing system according to claim 1, characterized in that, The acquisition of the voltage between the battery negative terminal and the vehicle ground, the high-voltage bus voltage, and the voltage between the battery pack positive terminal and the vehicle ground under various switching combinations includes acquiring the voltages under the following three switching states: State 1: The insulated positive parallel switch is closed, and the insulated negative parallel switch is open; State 2: The insulated positive parallel switch is open, and the insulated negative parallel switch is closed; State 3: The insulated positive parallel switch is open, and the insulated negative parallel switch is open.

4. The vehicle insulation testing system according to claim 3, characterized in that, The three switch combinations are switched sequentially, with a 10-20ms wait after each switch. The voltage is collected 5-8 times for each switch combination and the average value is taken.

5. The vehicle insulation testing system according to claim 1, characterized in that, The method for determining whether there is an insulation fault in the high voltage circuit of the vehicle and taking preventive measures includes: taking the smaller value between the insulation resistance of the positive terminal to ground and the insulation resistance of the negative terminal to ground of the vehicle as the insulation resistance value of the high voltage circuit of the vehicle, comparing it with a preset threshold, and if it is lower than the preset threshold, triggering an insulation fault in the vehicle, stopping the pilot heating, and disconnecting the DC positive relay and the DC negative relay.

6. The vehicle insulation testing system according to claim 1, characterized in that, The voltage of the positive terminal of the vehicle to the vehicle body ground is the sum of the voltage of the negative terminal of the battery pack to the vehicle body ground and the voltage of the high-voltage bus.

7. The vehicle insulation testing system according to claim 1, characterized in that, Solve the system of equations using Cramer's rule.

8. A method for testing the insulation of a whole vehicle, applied to a whole vehicle insulation testing system according to any one of claims 1-7, characterized in that, The method includes the following steps: Start pilot heating mode; Collect the voltage of the battery negative terminal to the vehicle ground, the high-voltage bus voltage, and the voltage of the battery pack positive terminal to the vehicle ground under each switch combination state. Based on voltage acquisition data, a system of equations was constructed to solve for the insulation resistance between the positive terminal and ground on the vehicle side and the insulation resistance between the negative terminal and ground on the vehicle side. Based on the insulation resistance values ​​of the positive and negative terminals of the vehicle to ground, determine whether there is an insulation fault in the high voltage of the vehicle and take preventive measures.

9. The whole vehicle insulation testing method according to claim 8, characterized in that, The activation of the pilot heating mode includes: After the vehicle plugs in the charging gun, it completes the charging handshake and enters the pilot heating preparation state. The main negative relay of the control battery pack is kept closed and the main positive relay is opened, so that the negative terminal of the battery pack is connected to the high voltage negative bus of the vehicle at the same potential, and the positive terminal of the battery pack is electrically disconnected from the high voltage positive bus of the vehicle. Close the DC positive relay and DC negative relay to connect the high-voltage power supply circuit between the external charging pile and the vehicle, and start the pilot heater.

10. A method for testing the insulation of a whole vehicle according to claim 8, characterized in that, The method of constructing a system of equations based on voltage acquisition data to solve for the insulation resistance values ​​of the positive terminal to ground and the negative terminal to ground on the vehicle side includes: The voltage of the vehicle's positive side to the vehicle ground is calculated based on the voltage of the negative terminal of the battery pack to the vehicle ground and the voltage of the high-voltage bus under each switch combination state. Based on the voltage acquisition data and the voltage between the positive terminal of the vehicle and the vehicle body ground, a system of equations is constructed; The system of equations was solved using Cramer's rule to obtain the insulation resistance values ​​of the positive terminal to ground and the negative terminal to ground on the vehicle side.

Images