CN105137194A - Automotive high-voltage circuit connection resistance fault prediction and location diagnosis circuit and method - Google Patents

Abstract

The invention provides a fault prediction positioning diagnosis circuit and a method for a connection resistor of an automobile high-voltage circuit, wherein the fault prediction positioning diagnosis circuit comprises the following steps: the current sensor is connected in series in a high-voltage circuit of the electric automobile, the current-voltage synchronous sampling circuit is respectively connected with a total positive terminal, a total negative terminal, a high-voltage circuit measuring point and the current sensor of the series battery pack, and the sequential sampling calculation unit is connected with the current-voltage synchronous sampling circuit. A diagnostic method using the diagnostic circuit is also provided. The invention realizes the on-line detection of the high-voltage circuit connecting resistance, the fault diagnosis, the fault location and the fault prediction of the high-voltage circuit connecting resistance, is beneficial to the maintenance personnel to quickly eliminate the high-voltage circuit connecting resistance fault after the high-voltage circuit connecting resistance fault occurs, improves the efficiency of maintenance operation and reduces the maintenance cost, can effectively prevent fire, equipment and personal injury caused by the high-voltage circuit connecting resistance fault, and has important significance and effect on the development of an electrically driven automobile.

Description

Automotive high-voltage circuit connection resistance fault prediction and location diagnosis circuit and method

technical field

The invention relates to an automobile fault diagnosis method, in particular to an electric drive automobile high-voltage circuit connection resistance fault prediction and location diagnosis circuit and method.

Background technique

Electric vehicles have become the focus and focus of global development. In order to meet the demand of high-power electric drive, the current passing through the high-voltage circuit of the car is as high as hundreds of amperes. High-voltage safety has become the key technology that needs to be solved first in the application of electric drive vehicles, and has a very important impact on the safety of the vehicle itself, the safety of drivers and passengers, and the safety of the vehicle operating environment. Among them, the high-voltage circuit connection resistance fault is an important content of the high-voltage safety management of electric drive vehicles. However, the existing high-voltage safety management system for electric drive vehicles has the problem of lack of functionality to realize the prediction of connection resistance faults. Generally, the fault is diagnosed after the high-voltage electrical connection resistance safety fault occurs in the vehicle, and then safety control is carried out. The lack of an early warning mechanism for the connection resistance fault results in the inability to remind the driver and occupants of the connection resistance fault that will occur before the connection resistance fault occurs. Failure to take effective protection, resulting in fire and other safety accidents.

A Chinese patent with the announcement number CN104442403A, the announcement date of March 25, 2015, and the patent name "A High-Voltage Loop Interlock System and Control Method for Electric Vehicles" was found through literature search of the prior art. The patented technology mainly includes the main discharge loop interlock unit, the motor three-phase loop interlock unit, the high-voltage accessory loop interlock unit and the slow charge loop interlock unit; the high-voltage plug-in of multiple main discharge devices in electric vehicles The interlocking mechanisms are connected in series to form the main discharge loop interlocking unit; the high-voltage plug-in interlocking mechanisms of multiple motor components are connected in series to form a motor three-phase loop interlocking unit; the high-voltage plug-in interlocking mechanisms of multiple high-voltage accessory devices are connected in series to form High-voltage accessory loop; the interlock mechanism of the high-voltage plug-in of multiple slow charging devices is connected in series to form a slow charging loop interlocking unit; the main discharge loop interlocking unit, the motor three-phase loop interlocking unit, and the high-voltage accessory loop interlocking unit The lock unit and the slow charging loop interlock unit are respectively connected to the CAN bus of the electric vehicle, which can detect the disconnection and poor contact of the high-voltage circuit interlock mechanism or interlock unit, thereby indirectly detecting the connection status of the high-voltage circuit. Its shortcoming is that it cannot directly detect the connection resistance failure of the high-voltage circuit, nor can it predict the connection resistance failure. In the case that the interlock mechanism or the interlock unit is still reliably connected, the actual high-voltage circuit failure that has occurred cannot be detected. Risk of connection resistor failure.

Contents of the invention

In view of the defects in the prior art, the purpose of the present invention is to provide a circuit and diagnosis method for predicting and locating connection resistance faults of electric drive vehicles, which can effectively solve the problem of connection resistance faults existing in the high voltage safety management system of electric drive vehicles Realize the functional lack of prediction and diagnosis, remind the driver and passengers to take effective protection against the upcoming connection resistance fault before the connection resistance fault occurs, and make it possible for the vehicle control system to start the connection resistance fault prevention and control strategy in advance, thereby Avoid safety accidents caused by connection resistance failure.

To achieve the above object, the present invention is achieved through the following technical solutions:

According to one aspect of the present invention, a circuit for predicting and locating faults connected to resistances of high-voltage circuits of electric vehicles is provided, including a current sensor, a current and voltage synchronous sampling circuit, and a sequential sampling calculation unit, wherein: the current sensor is connected in series with the high-voltage circuit of the electric vehicle Among them, the current and voltage synchronous sampling circuit is respectively connected with the total positive terminal, the total negative terminal, the high voltage circuit measuring point, and the current sensor of the series battery pack, and the sequential sampling calculation unit is synchronously sampled with the current and voltage circuit is connected.

Preferably, the current and voltage synchronous sampling circuit adopts multiple sampling and holding chips.

Preferably, the current and voltage synchronous sampling circuit is also connected to a plurality of high-voltage circuit measuring points, so as to realize diagnosis, prediction and location of connection resistance faults of different high-voltage circuit segments.

Preferably, the measuring point of the high voltage circuit is the high voltage input end of the load;

Preferably, the high-voltage circuit of the electric drive vehicle is connected to a resistance fault prediction and location diagnosis circuit, and further includes a vehicle controller, and the sequential sampling calculation unit is communicatively connected to the vehicle controller.

Preferably, the sequential sampling calculation unit is provided with a communication module, and the communication module sends the connection resistance fault level, the connection resistance fault location, the remaining time of the predicted connection resistance fault occurrence, and the connection resistance value information to the vehicle controller.

According to another aspect of the present invention, a method for predicting and locating the connection resistance fault prediction and location diagnosis method of the high-voltage circuit of an electric drive vehicle is provided. Using the above-mentioned electric drive vehicle high-voltage circuit connection resistance fault prediction and positioning circuit, the terminal voltage of the battery pack in series is Vb, load The voltage of the input end relative to the total negative terminal of the battery pack in series is Va, the current of the high voltage circuit is I, the total internal resistance of the battery pack in series is R0, the connection resistance of the high voltage circuit between the measuring point of the high voltage circuit and the battery pack in series is Rc, The connection resistance calculation enables the current difference judgment value △I and the maximum time window △T, the judgment value of the jth level connection resistance fault is Rj, and the connection resistance fault prediction and positioning diagnosis method includes the following steps:

Step 1, sequentially calculate the sampling unit through the current and voltage synchronous sampling circuit at the i moment Ti to synchronously sample the terminal voltage Vbi of the series battery pack, the voltage Vai and the current Ii of the high-voltage circuit measuring point relative to the total negative terminal of the series battery pack;

Step 2, sequentially calculate the terminal voltage Vbj of the series battery pack, the voltage Vaj and the current Ij of the high-voltage circuit measuring point relative to the total negative terminal of the series battery pack through the current and voltage synchronous sampling circuit synchronous sampling circuit at the j moment Tj;

Step 3, if the time interval between Tj and Ti is less than ΔT and the absolute value of the difference between Ii and Ij is greater than ΔI, use the formula R0=|Vbj-Vbi|/|Ij-Ii| Internal resistance R0, further use the formula Rc=|Vaj-Vai|/|Ij-Ii|-R0 to calculate the high-voltage circuit connection resistance Rc between the high-voltage circuit measuring point and the series battery pack;

Step 4, if Rc≥Rj, it is judged that the high-voltage circuit between the high-voltage circuit measuring point and the series battery pack has a jth-level connection resistance fault, so as to realize the online diagnosis of the high-voltage circuit connection resistance fault level;

Step 5, using the m (m≥3) connection resistance values Rc calculated in step 3 in the latest period of time, set the calculation time of the first Rc among the m Rcs as T ₀ and the calculation time of each Rc and T The difference between ₀ and 0 is t, and the change curve t=f(Rc) between the time t and the connection resistance value Rc is fitted online, and the time required for Rc to reach Rj is calculated by using the change curve, so as to realize the connection between the high-voltage circuit measuring point and Prediction of the remaining time for the jth level high-voltage circuit connection fault to occur in the high-voltage circuit between the series battery packs;

Step 6: Repeat steps 1 to 5 above to calculate the high-voltage circuit connection resistance fault level, the high-voltage circuit connection resistance fault location, the remaining time for predicting the high-voltage circuit connection resistance fault occurrence, and the high-voltage circuit connection resistance value at the next moment.

For other high-voltage circuit measuring points, repeat steps 1 to 6 to locate the connection resistance fault of the high-voltage circuit.

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

(1) The present invention realizes the diagnosis of the fault level of the connection resistance of the high-voltage circuit, thereby making it possible for the vehicle control system, the battery management system, etc. to perform more scientific and reasonable high-voltage safety management according to the deterioration of the connection resistance of the high-voltage circuit.

(2) The present invention realizes the location of the connection resistance fault of the high-voltage circuit, which helps the maintenance personnel to quickly eliminate the insulation fault after the connection resistance fault of the high-voltage circuit occurs, improves the efficiency of the maintenance operation and reduces the maintenance cost, and can also be used for related Provide a basis for improving the design.

(3) The present invention realizes the prediction of the failure of the connection resistance of the high-voltage circuit, thereby making it possible to eliminate the risk of failure of the connection resistance of the high-voltage circuit in advance.

(4) Tests show that the high-voltage circuit connection resistance prediction and positioning diagnosis method of the present invention has the advantages of high-voltage circuit connection resistance detection error≤6%, high-voltage circuit connection resistance fault diagnosis is accurate, high-voltage circuit connection resistance fault location is accurate and high-voltage circuit connection resistance Fault prediction is accurate with high precision and high reliability.

(5) The high-voltage circuit connection resistance prediction and positioning diagnosis method of the present invention is not only applicable to electric vehicles, but also applicable to hybrid vehicles, fuel cell vehicles and even energy storage systems, and is also applicable to series battery packs, series capacitor banks, etc. are applicable.

(6) The method for predicting, locating, and diagnosing high-voltage circuit connection resistance faults of the present invention fills up the gaps in the existing similar technologies, effectively prevents fires, equipment and personal injuries caused by high-voltage circuit connection resistance faults, and has a positive impact on the development of electric vehicles. significance and role.

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Fig. 1 is the block diagram of electric vehicle high-voltage circuit connection resistance fault prediction location diagnosis circuit of the present invention;

Fig. 2 is a flow chart of the method for predicting, locating and diagnosing faults connected to high-voltage circuits of electric vehicles according to the present invention.

In _Fig . 1, V _b ^R is the terminal voltage of the series battery pack, Vbi and Vbj are the terminal voltages of the series battery pack sent to the sequential sampling calculation unit by the current and voltage synchronous sampling circuit through the current and voltage synchronous sampling circuit, Vbi and Vbj respectively ^. V _a ^R is the voltage of the load input terminal and the total negative terminal of the series battery pack, Vai and Vaj are respectively the voltages of V _a ^R sent to the load input terminal of the sequential sampling calculation unit and the total negative terminal of the series battery pack through the synchronous sampling circuit, I ^R is the current signal output by the current sensor, Ii and Ij are the current values of the high-voltage circuit that I ^R sends to the sequential sampling calculation unit through the synchronous sampling circuit, AD1, AD2, and AD3 are the three modulus interfaces of the control unit, and CAN is CAN communication interface, S is the synchronous hold sampling command of the control unit to the synchronous sampling circuit;

In Fig. 2, at the i-th moment Ti synchronously samples the terminal voltage of the series-connected battery pack as Vbi, the voltage of the high-voltage circuit measuring point relative to the total negative terminal of the series-connected battery pack is Vai, and the current is Ii, and at the j-th moment Tj synchronously samples the series-connected battery pack The terminal voltage of the high-voltage circuit is Vbj, the voltage of the high-voltage circuit measuring point relative to the total negative terminal of the series battery pack is Vaj, and the current is Ij.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

As shown in Figure 1, the present invention is a high-voltage circuit connection resistance fault prediction circuit for an electric drive vehicle, including a current sensor, a current and voltage synchronous sampling circuit, and a sequential sampling calculation unit, wherein: the current sensor is connected in series in the high-voltage circuit of the electric vehicle , the current and voltage synchronous sampling circuit is respectively connected to the total positive terminal, the total negative terminal, the load high voltage input terminal, and the current sensor of the series battery pack, and the sequential sampling calculation unit is synchronized with the current and voltage The sampling circuit is connected.

Further, the current and voltage synchronous sampling circuit adopts multiple sampling and holding chips.

Further, the current and voltage synchronous sampling circuit is also connected to a plurality of high-voltage circuit measuring points, so as to realize diagnosis, prediction and location of connection resistance faults of different high-voltage circuit segments.

Further, the measuring point of the high voltage circuit is the high voltage input end of the load;

Further, the electric vehicle high-voltage circuit is connected to a resistance fault prediction and location diagnosis circuit, and also includes a vehicle controller, and the sequential sampling calculation unit is connected to the vehicle controller in communication.

Further, the sequential sampling calculation unit is provided with a communication module, and the communication module sends the connection resistance fault level, the connection resistance fault location, the remaining time of the predicted connection resistance fault occurrence, and the connection resistance value information to the vehicle controller.

In combination with Fig. 1, as shown in Fig. 2, assume that the terminal voltage of the series-connected battery pack is Vb, the voltage of the load input terminal relative to the total negative terminal of the series-connected battery pack is Va, the high-voltage circuit current is I, and the total internal resistance of the series-connected battery pack R0, the connection resistance of the high-voltage circuit between the high-voltage circuit measuring point and the series battery pack is Rc, the connection resistance calculates the judgment value of the enabling current difference △I and the maximum time window △T, and the judgment value of the j-th level connection resistance fault is Rj , the principle and process of the electric vehicle high-voltage circuit connection resistance fault prediction and location diagnosis method of the present invention are as follows:

Step 1, sequentially calculate the sampling unit through the current and voltage synchronous sampling circuit at the i moment Ti to synchronously sample the terminal voltage Vbi of the series battery pack, the voltage Vai and the current Ii of the high-voltage circuit measuring point relative to the total negative terminal of the series battery pack;

Step 2, sequentially calculate the terminal voltage Vbj of the series battery pack, the voltage Vaj and the current Ij of the high-voltage circuit measuring point relative to the total negative terminal of the series battery pack through the current and voltage synchronous sampling circuit synchronous sampling circuit at the j moment Tj;

Step 3, if the time interval between Tj and Ti is less than ΔT and the absolute value of the difference between Ii and Ij is greater than ΔI, use the formula R0=|Vbj-Vbi|/|Ij-Ii| Internal resistance R0, further use the formula Rc=|Vaj-Vai|/|Ij-Ii|-R0 to calculate the high-voltage circuit connection resistance Rc between the high-voltage circuit measuring point and the series battery pack;

Step 4, if Rc≥Rj, it is judged that the high-voltage circuit between the high-voltage circuit measuring point and the series battery pack has a jth-level connection resistance fault, so as to realize the online diagnosis of the high-voltage circuit connection resistance fault level;

Step 5, using the m (m≥3) connection resistance values Rc calculated in step 3 in the latest period of time, set the calculation time of the first Rc among the m Rcs as T ₀ and the calculation time of each Rc and T The difference between ₀ and 0 is t, and the change curve t=f(Rc) between the time t and the connection resistance value Rc is fitted online, and the time required for Rc to reach Rj is calculated by using the change curve, so as to realize the connection between the high-voltage circuit measuring point and Prediction of the remaining time for the jth level high-voltage circuit connection fault to occur in the high-voltage circuit between the series battery packs;

Step 6. Through the CAN communication interface of the communication module, the high-voltage circuit connection resistance fault level, the high-voltage circuit connection resistance fault location, the remaining time of the high-voltage circuit connection resistance fault prediction, and the high-voltage circuit connection resistance fault calculated in the above steps 1 to 5 are calculated. The value information is sent to the vehicle controller.

Step 7: Repeat the above steps 1 to 6 to calculate the high-voltage circuit connection resistance fault level, the high-voltage circuit connection resistance fault location, the remaining time for predicting the occurrence of the high-voltage circuit connection resistance fault, and the high-voltage circuit connection resistance value information at the next moment.

Step 8, repeat steps 1 to 7 for other high-voltage circuit measuring points, so as to locate the connection resistance fault of the high-voltage circuit.

According to the high-voltage circuit connection resistance fault prediction and positioning diagnosis method, the calculated high-voltage circuit connection resistance fault level, high-voltage circuit connection resistance fault location, predicted remaining time for high-voltage circuit connection resistance fault occurrence, high-voltage circuit connection resistance value and other information, It can also be directly displayed on the instrument to remind the driver, and can also be transmitted to the monitoring center through remote communication to realize statistical analysis and big data processing of the connection status of a large number of high-voltage circuits of vehicles.

The invention is applied to electric drive vehicles: it not only realizes the diagnosis of the fault level of the high-voltage circuit connection, but also makes it possible for the vehicle control system and the battery management system to carry out more scientific and reasonable high-voltage electric safety management according to the deterioration of the high-voltage circuit connection ; It also helps the maintenance personnel to quickly eliminate the high-voltage circuit connection fault after the high-voltage circuit connection fault occurs, improve the efficiency of the maintenance operation and reduce the maintenance cost, and also provide a basis for related improvement design; it also enables the high-voltage circuit connection fault to be eliminated in advance risk becomes possible. The high-voltage circuit connection prediction and positioning diagnosis method of the present invention fills in the gaps in the existing similar technologies, and effectively prevents further fires, equipment and personal injuries caused by the huge heat generated when the high-voltage circuit connection fails, and has a negative impact on the electric vehicle industry. The development of culture is of great significance and role. Tests have shown that the high-voltage circuit connection resistance fault prediction and positioning diagnosis method of the present invention has the advantages of high-voltage circuit connection resistance detection error ≤ 6%, high-voltage circuit connection fault diagnosis accuracy, high-voltage circuit connection fault location accuracy and high-voltage circuit connection fault prediction accuracy. precision and high reliability.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims (10)

1. An automobile high-voltage circuit connection resistance fault prediction and positioning diagnostic circuit, including a current sensor, a current-voltage synchronous sampling circuit, and a sequential sampling calculation unit, wherein: the current sensor is connected in series in the electric vehicle high-voltage circuit, and the current and voltage synchronous sampling The circuit is respectively connected with the total positive terminal, the total negative terminal of the series battery pack, the measuring point of the high-voltage circuit, and the current sensor, and the sequential sampling calculation unit is connected with the current and voltage synchronous sampling circuit. 2. The automobile high-voltage circuit connection resistance fault prediction and location diagnosis circuit according to claim 1, characterized in that, the current and voltage synchronous sampling circuit adopts a multi-channel sampling and holding chip. 3. The automotive high-voltage circuit connection resistance fault prediction and location diagnosis circuit according to claim 1, characterized in that there are multiple measuring points for the high-voltage circuit. 4 . The automotive high-voltage circuit connection resistance fault prediction and location diagnosis circuit according to claim 1 , further comprising a vehicle controller, which is communicatively connected with the sequential sampling calculation unit. 5. The automotive high-voltage circuit connection resistance fault prediction and positioning diagnostic circuit according to claim 1, wherein the sequential sampling calculation unit is provided with a communication module, and the communication module sends the connection resistance fault information to the vehicle controller . 6. The automobile high-voltage circuit connection resistance fault prediction and positioning diagnostic circuit according to claim 1, wherein the connection resistance fault information includes connection resistance fault level, connection resistance fault location, remaining time for predicting connection resistance fault occurrence or Connection resistor value information. 7. A method for predicting and locating a fault in connection with a high-voltage circuit of an automobile, characterized in that, utilizing any one of claims 1 to 6, the circuit for predicting and locating a fault in connection with a resistance in a high-voltage circuit of a motor vehicle is used to set the terminal voltage of a battery pack connected in series Vb, the voltage of the load input terminal relative to the total negative terminal of the battery pack in series is Va, the current of the high-voltage circuit is I, the total internal resistance of the battery pack in series is R0, the high-voltage circuit connection between the measuring point of the high-voltage circuit and the battery pack in series The resistance is Rc, the connection resistance calculation enables the current difference judgment value △I and the maximum time window △T, and the judgment value of the j-th level connection resistance fault is Rj, including the following steps: Step 1, sequentially calculate the sampling unit through the current and voltage synchronous sampling circuit at the i moment Ti to synchronously sample the terminal voltage Vbi of the series battery pack, the voltage Vai and the current Ii of the high-voltage circuit measuring point relative to the total negative terminal of the series battery pack; Step 2, sequentially calculate the terminal voltage Vbj of the series battery pack, the voltage Vaj and the current Ij of the high-voltage circuit measuring point relative to the total negative terminal of the series battery pack through the current and voltage synchronous sampling circuit synchronous sampling circuit at the j moment Tj; Step 3, if the time interval between Tj and Ti is less than ΔT and the absolute value of the difference between Ii and Ij is greater than ΔI, use the formula R0=|Vbj-Vbi|/|Ij-Ii| Internal resistance R0, further use the formula Rc=|Vaj-Vai|/|Ij-Ii|-R0 to calculate the high-voltage circuit connection resistance Rc between the high-voltage circuit measuring point and the series battery pack; Step 4, if Rc≥Rj, it is judged that the high-voltage circuit between the high-voltage circuit measuring point and the series battery pack has a jth-level connection resistance fault, so as to realize the online diagnosis of the high-voltage circuit connection resistance fault level; Step 5, using the m connection resistance values Rc calculated in step 3 in the most recent period, m≥3, set the calculation time of the first Rc among the m Rcs as T ₀ and the calculation time of each Rc and T ₀ The difference is t, and the change curve t=f(Rc) between the time t and the connection resistance value Rc is fitted online, and the time required for Rc to reach Rj is calculated by using the change curve, so as to realize the high-voltage circuit measuring point and series connection Prediction of the remaining time for the jth level high-voltage circuit connection fault to occur in the high-voltage circuit between the battery packs. 8. The automobile high-voltage circuit connection resistance fault prediction and location diagnostic method according to claim 7, is characterized in that, also comprises the following steps: Step 6. Through the CAN communication interface of the communication module, the high-voltage circuit connection resistance fault level, the high-voltage circuit connection resistance fault location, the remaining time of the high-voltage circuit connection resistance fault prediction, and the high-voltage circuit connection resistance fault calculated in the above steps 1 to 5 are calculated. The value information is sent to the vehicle controller. 9. The automobile high-voltage circuit connection resistance fault prediction and location diagnosis method according to claim 8, is characterized in that, also comprises the following steps: Step 7: Repeat the above steps 1 to 6 to calculate the high-voltage circuit connection resistance fault level, the high-voltage circuit connection resistance fault location, the remaining time for predicting the occurrence of the high-voltage circuit connection resistance fault or the high-voltage circuit connection resistance value information at the next moment. 10. The automobile high-voltage circuit connection resistance fault prediction and location diagnosis method according to claim 8, is characterized in that, also comprises the following steps: Step 8, repeat steps 1 to 7 for other high-voltage circuit measuring points, so as to locate the connection resistance fault of the high-voltage circuit.