Contactor fault identification device, charging control method and electric vehicle

Abstract

This invention discloses a contactor anomaly identification device, a charging control method, and an electric vehicle, belonging to the field of new energy vehicle charging management technology. The contactor anomaly identification device includes a charging port, contactors, temperature sensors, and a detection and processing module. At least one set of contactors is connected in parallel to each of the positive and negative output terminals of the power battery. The other end of each set of contactors is connected via a busbar. There is at least one charging port, and each charging port is connected to the busbar via a high-voltage cable. A temperature sensor is installed on the contact post of each contactor, and the detection and processing module is connected to the temperature sensor via signal lines. By real-time detection of the temperature on the contactor contacts and its relationship to the current, a two-dimensional current limiting table is formed. The charging current is adjusted or charging is stopped in a timely manner, effectively solving the problem of charging safety hazards caused by the inability to obtain the actual state of the contactors under the parallel contactor shunt method, and improving the reliability and safety of the charging system.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicle charging management technology, and more specifically to a contactor anomaly identification device, a charging control method, and an electric vehicle. Background Technology

[0002] With the rapid development and popularization of new energy vehicles, the charging experience of electric vehicles has become one of the important factors restricting their development, especially the charging speed of commercial vehicles with large battery capacity. Currently, single-gun DC charging for electric vehicles is typically 250A, and dual-gun DC charging is 400A. However, with the increase in battery capacity and charging rate, as well as the introduction of liquid-cooled supercharging piles, the demand for charging power for electric vehicles is constantly increasing. The maximum capacity of single-gun DC charging has exceeded 1000A, which places higher demands on the voltage and overcurrent withstand capabilities of the electrical components in the charging circuit.

[0003] One common approach is to increase the overcurrent capacity of the charging contactor to handle the charging current required for overcharging. However, this method often results in larger contactors, higher costs, and poor compatibility. Another approach is to use contactors with auxiliary contacts connected in parallel to shunt the current. For example, for a charging current of 1000A, two 600A contactors are connected in parallel. Ideally, each contactor receives 500A of current. However, the reliability of auxiliary contacts is poor. When an auxiliary contact misinterprets a contactor as closed (when it is actually open), the contactor connected in parallel will have to carry the entire current. Prolonged overcurrent can damage the auxiliary contactor, and connected electrical components, such as copper busbars, may also experience overheating and erosion, posing safety hazards. Summary of the Invention

[0004] This invention provides a contactor anomaly identification device, a charging control method, and an electric vehicle, aiming to solve the above-mentioned shortcomings of existing electric vehicle charging contactors.

[0005] The present invention adopts the following technical solution:

[0006] A contactor anomaly identification device includes a charging port, a first contactor, a second contactor, a temperature sensor, and a detection and processing module. At least one set of first contactors is connected in parallel to the positive output terminal of a power battery. Each set of first contactors includes at least two first contactors connected in parallel, and the other end of each set is connected via a busbar. At least one set of second contactors is connected in parallel to the negative output terminal of the power battery. Each set of second contactors includes at least two second contactors connected in parallel, and the other end of each set is connected via a busbar. There is at least one charging port, and each charging port is connected to one busbar and one busbar via a high-voltage cable. A temperature sensor is provided on the contact terminal of each first contactor and on the contact terminal of each second contactor. The detection and processing module is connected to the temperature sensor via signal lines to detect the sampling values ​​of each temperature sensor in real time. The detection and processing module is also connected to a BMS via signal lines.

[0007] In a preferred embodiment, the busbar one is connected to the contact post of contactor one in close proximity; the busbar two is connected to the contact post of contactor two in close proximity.

[0008] In a preferred embodiment, there are two charging ports, including charging port 1 and charging port 2; contactors K1, K2, K5, and K6 are connected in parallel to the positive output terminal of the power battery, and contactors K3, K4, K7, and K8 are connected in parallel to the negative output terminal of the power battery; temperature sensors T1 to T8 are correspondingly provided on the contact posts of contactors K1 to K8; charging port 1, contactors K1 to K4, temperature sensors T1 to T4, and electrical components for circuit connection constitute charging circuit 1, and charging port 2, contactors K5 to K8, temperature sensors T5 to T8, and electrical components for circuit connection constitute charging circuit 2.

[0009] The present invention also provides a charging control method, employing the above-mentioned contactor anomaly identification device, comprising the following steps:

[0010] Step 1: Initialize system configuration;

[0011] Step 2: The BMS determines whether it is in charging mode. If yes, proceed to Step 3; otherwise, wait.

[0012] Step 3: The detection and processing module detects the sampled values ​​of the temperature sensor in real time, converts them into corresponding temperature values, and sends them to the BMS;

[0013] Step 4: After the BMS obtains the temperature value, it queries the table of contact temperature and allowable continuous overcurrent capacity to obtain the real-time allowable continuous overcurrent capacity value of each contactor.

[0014] Step 5: BMS determines whether it is a dual-gun asynchronous configuration. If yes, proceed to step 6; otherwise, proceed to step 7.

[0015] Step Six: The BMS adjusts the requested charging current of each branch in real time, and then executes Step Eight; where, the requested current of charging circuit 1 = min(real-time allowable charging capacity of the battery system of charging circuit 1, 2 * allowable continuous overcurrent capacity of the contactor of charging circuit 1, and the output limit of the charging pile), and the requested current of charging circuit 2 = min(real-time allowable charging capacity of the battery system - requested current of charging circuit 1, 2 * allowable continuous overcurrent capacity of the contactor of charging circuit 2, and the output limit of the charging pile).

[0016] Step 7: The BMS adjusts the system's requested charging current and proceeds to Step 8; where, in single-gun mode, the value is min(real-time allowable charging capacity of the battery system, 2 * allowable continuous overcurrent capacity of the contactor in the charging circuit, and the charging pile output limit); in dual-gun mode, the value is min{real-time allowable charging capacity of the battery system, 2 * min(allowable continuous overcurrent capacity of contactor 1 in charging circuit, allowable continuous overcurrent capacity of contactor 2 in charging circuit), and the charging pile output limit}.

[0017] Step 8: Determine whether the temperature difference between the contactor contacts connected in parallel in each charging circuit exceeds the preset threshold. If so, identify that the contactor may have an abnormal disconnection, issue an alarm, and stop charging. If not, return to Step 5 and dynamically adjust the charging request current in real time according to the allowable overcurrent capacity corresponding to the contactor contact temperature until the charging is fully charged and the charging is stopped.

[0018] Furthermore, step one above also includes setting the initial allowable continuous overcurrent capacity value of the contactor, with the initial value set by default according to the maximum allowable value.

[0019] Furthermore, step three above also includes determining whether the temperature sensor is disconnected. If it is disconnected, an alarm is triggered and charging of the corresponding circuit is stopped.

[0020] Preferably, the relationship table between contact temperature and allowable continuous overcurrent capacity in step four above is defined experimentally, specifically including: setting different ambient temperatures and different currents to measure the contact temperature rise and impedance of the contactor, and defining the allowable continuous overcurrent capacity value of the contactor at different temperatures in combination with the safety threshold of the contactor. The undefined intermediate values ​​are obtained by linear interpolation.

[0021] Preferably, the real-time allowable charging capacity of the battery system in the above-mentioned charging circuit 1 is min(real-time charging window value of the battery system, pre-overvoltage limit value, allowable value of the circuit cable, allowable value of the circuit connector, and allowable value of the circuit socket); wherein, the allowable values ​​of the circuit cable, circuit connector, and circuit socket are related to the vehicle design and are defined after the vehicle model is finalized; the real-time charging window value of the battery system is a lookup value, that is, the allowable charging current value of the power battery pack itself corresponding to the current SOC and current cell temperature; the pre-overvoltage limit value is the allowable charging current value under different single cell voltages set by the BMS to prevent battery overcharging.

[0022] Preferably, the continuous overcurrent capability of the charging circuit contactor is the minimum value among the continuous overcurrent capabilities corresponding to the contact temperatures of all contactors in the charging circuit.

[0023] The present invention also provides an electric vehicle, including a vehicle body, a power battery, and a contactor anomaly detection device.

[0024] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following advantages:

[0025] 1. This invention integrates a temperature sensor on the contact post of the contactor. By detecting the temperature on the contactor contact in real time and relating it to the current, a two-dimensional current limiting meter is formed. This allows for timely detection of abnormalities in parallel contactors, timely adjustment of the charging current, or stopping of charging. This effectively solves the problem of charging safety hazards caused by the inability to obtain the actual state of the contactors in the parallel contactor current-sharing method, and improves the reliability and safety of the charging system.

[0026] 2. This invention identifies contactor anomalies based on contact temperature, without increasing the contactor size or adding auxiliary contacts. It is highly reliable, low-cost, and has good compatibility, overcoming the shortcomings of traditional solutions such as large size, high cost, and poor compatibility.

[0027] 3. The charging control method of the present invention enables the BMS to dynamically adjust the charging current according to different configuration requirements, thereby realizing the flexibility of the charging strategy and improving the charging efficiency. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a contactor anomaly identification device according to Embodiment 1 of the present invention.

[0029] Figure 2 This is a schematic flowchart of the charging control method according to Embodiment 2 of the present invention. Detailed Implementation

[0030] The following reference Figure 1 Specific embodiments of the present invention will be described below. Many details are described below to provide a comprehensive understanding of the invention; however, those skilled in the art can implement the invention without these details. Well-known components, methods, and processes will not be described in detail hereafter. Example

[0031] This embodiment provides a contactor anomaly identification device, including a charging port, multiple contactors, a temperature sensor, and a detection and processing module. For ease of explanation, this embodiment provides a configuration with two charging ports and two contactors connected in parallel.

[0032] Reference Figure 1There are two charging ports, namely charging port 1 and charging port 2. There are eight contactors, specifically contactors K1 to K8. Contactors K1 and K2 have one end connected to the positive output terminal of the power battery, and the other end connected via a busbar; contactors K5 and K6 have one end connected to the positive output terminal of the power battery, and the other end connected via a busbar; contactors K3 and K4 have one end connected to the negative output terminal of the power battery, and the other end connected via a busbar; contactors K7 and K8 have one end connected to the negative output terminal of the power battery, and the other end connected via a busbar.

[0033] The aforementioned charging port 1 is connected to the busbars connected to contactors K1 and K2, and the busbars connected to contactors K3 and K4, respectively, via high-voltage cables. The charging port 2 is connected to the busbars connected to contactors K5 and K6, and the busbars connected to contactors K7 and K8, respectively, via high-voltage cables.

[0034] The busbars and contactor contacts should be connected as close as possible to each other, that is, the connection position between the busbars and the contactor should be as close as possible to the contactor contacts to minimize the impact of impedance differences in the line copper busbars or cable assemblies and prevent overcurrent in the contactor.

[0035] Temperature sensors T1 to T8 are respectively installed on the contact terminals of the contactors K1 to K8. The detection and processing module is connected to the temperature sensors T1 to T8 via signal lines to detect the sampled values ​​of each temperature sensor in real time. The detection and processing module is also connected to the BMS via signal lines. Based on the sampled temperature values, the BMS looks up the overcurrent capacity of each contactor in a table, and then makes a comprehensive judgment on the system's overcurrent capacity to request a safe charging current from the charging pile.

[0036] Although the above embodiments only show the form of two charging ports and two contactors connected in parallel, the solution of the present invention is also applicable to the form of two or more charging ports and two or more contactors connected in parallel. Example

[0037] This embodiment provides a charging control method, employing the aforementioned contactor anomaly identification device, with reference to... Figure 2 This includes the following steps:

[0038] Step 1: Initialize system configuration.

[0039] Step 2: The BMS determines whether it is in charging mode. If so, proceed to Step 3; otherwise, wait.

[0040] Step 3: The detection and processing module detects the sampled values ​​of temperature sensors T1~T8 in real time, converts them into corresponding temperature values, and sends them to the BMS.

[0041] Step 4: After the BMS obtains the temperature value, it queries the table of contact temperature and allowable continuous overcurrent capacity to obtain the real-time allowable continuous overcurrent capacity value of each contactor.

[0042] Step 5: BMS determines whether it is a dual-gun asynchronous configuration. If yes, proceed to step 6; otherwise, proceed to step 7.

[0043] Step Six: The BMS adjusts the requested charging current of each branch in real time, and then executes Step Eight; where, the requested current of charging circuit 1 = min (real-time allowed charging capacity of the battery system of charging circuit 1, 2 * allowed continuous overcurrent capacity of the contactor of charging circuit 1, and the output limit of the charging pile), and the requested current of charging circuit 2 = min (real-time allowed charging capacity of the battery system - requested current of charging circuit 1, 2 * allowed continuous overcurrent capacity of the contactor of charging circuit 2, and the output limit of the charging pile).

[0044] Step 7: The BMS adjusts the system's requested charging current and proceeds to Step 8; where, in single-gun mode, the value is min(real-time allowable charging capacity of the battery system, 2 * allowable continuous overcurrent capacity of the contactor in the charging circuit, and the charging pile output limit), and in dual-gun mode, the value is min{real-time allowable charging capacity of the battery system, 2 * min(allowable continuous overcurrent capacity of contactor 1 in charging circuit, allowable continuous overcurrent capacity of contactor 2 in charging circuit), and the charging pile output limit}.

[0045] Step 8: Determine whether the temperature difference between the contactor contacts connected in parallel in each charging circuit exceeds the preset threshold. If so, identify that the contactor may have an abnormal disconnection, issue an alarm, and stop charging. If not, return to Step 5 and dynamically adjust the charging request current in real time according to the allowable overcurrent capacity corresponding to the contactor contact temperature until the charging is fully charged and the charging is stopped.

[0046] Step one above also includes setting the initial allowable continuous overcurrent capacity value of the contactor. The initial value is set by default according to the maximum allowable value. For example, for a contactor with a rated current of 300A, the initial allowable continuous overcurrent capacity value of the contactor is set to 300A.

[0047] Step three above also includes determining whether the temperature sensor is disconnected. If it is disconnected, an alarm will be triggered and the charging of the corresponding circuit will be stopped.

[0048] The relationship between contact temperature and permissible continuous overcurrent capacity in step four above is defined experimentally. Specifically, it includes: measuring the contact temperature rise and impedance of the contactor at different ambient temperatures and currents; defining the permissible continuous overcurrent capacity value of the contactor at different temperatures based on the contactor's safety threshold; and obtaining undefined intermediate values ​​using linear interpolation. For example, as shown in Table 1 below, the current contactor contact temperature is 112℃, corresponding to a permissible continuous overcurrent capacity value of 280A.

[0049] Temperature / °C ≤110 115 120 125 130 ≥135 Allowable current / A 300 250 200 150 100 0

[0050] Table 1 Relationship between contact temperature and allowable continuous overcurrent capacity

[0051] The above-mentioned dual-gun asynchronous configuration means that the vehicle is equipped with two charging ports. The two charging ports are independent of each other and can be charged independently through two charging piles without affecting each other. The charging current request for each charging port is also independent.

[0052] The charging circuit 1 includes a charging port 1, contactors K1~K4, temperature sensors T1~T4, and electrical components for circuit connection; the charging circuit 2 includes a charging port 2, contactors K5~K8, temperature sensors T5~T8, and electrical components for circuit connection.

[0053] The real-time allowable charging capacity of the battery system in the above charging circuit 1 is min(real-time charging window value of the battery system, pre-overvoltage limit value, allowable value of the circuit cable, allowable value of the circuit connector, and allowable value of the circuit socket); among which, the allowable values ​​of the circuit cable, circuit connector, and circuit socket are related to the vehicle design and are defined after the vehicle model is finalized; the real-time charging window value of the battery system is a lookup value, that is, the allowable charging current value of the power battery pack itself corresponding to the current SOC and current cell temperature; the pre-overvoltage limit value is the allowable charging current value under different single cell voltages set by the BMS to prevent battery overcharging.

[0054] The above-mentioned allowable values ​​for charging piles are the output limits sent by the charging piles to the BMS.

[0055] The continuous overcurrent capability of the above-mentioned charging circuit contactor is the minimum value among the continuous overcurrent capabilities corresponding to the contact temperatures of all contactors in the charging circuit.

[0056] The above are the specific steps of this embodiment. By detecting the temperature on the contactor contacts in real time and relating it to the current, abnormal problems of parallel contactors can be detected in a timely manner, and the charging current can be adjusted or charging can be stopped in time. This effectively solves the problem of charging safety hazards caused by the inability to obtain the actual state of the contactors under the parallel contactor shunt method, and can improve the safety of the charging system. The abnormal identification method based on contact temperature does not require increasing the size of the contactor or adding auxiliary contacts. It has high reliability, low cost, and good compatibility, overcoming the disadvantages of traditional solutions such as large size, high cost, and poor compatibility.

[0057] The above are merely specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept shall be considered as infringing upon the protection scope of the present invention.

Claims

1. A charging control method, characterized in that, A contactor anomaly detection device is employed, comprising a charging port, contactor one, contactor two, a temperature sensor, and a detection and processing module. At least one set of contactors one is connected in parallel to the positive output terminal of the power battery, each set including at least two contactors one in parallel, and the other end of each set connected via busbar one. At least one set of contactors two is connected in parallel to the negative output terminal of the power battery, each set including at least two contactors two in parallel, and the other end of each set connected via busbar two. Each charging port is connected to one busbar one and one busbar two via high-voltage cables. A temperature sensor is installed on the contact terminal of each contactor one and each contact terminal two. The detection and processing module is connected to the temperature sensor via signal lines for real-time detection. The detection and processing module measures the sampling values ​​of each temperature sensing probe and is also connected to the BMS via a signal line. Busbar 1 is connected to the contact post of contactor 1 in close proximity. Busbar 2 is connected to the contact post of contactor 2 in close proximity. There are two charging ports, including charging port 1 and charging port 2. Contactors K1, K2, K5, and K6 are connected in parallel to the positive output terminal of the power battery, and contactors K3, K4, K7, and K8 are connected in parallel to the negative output terminal of the power battery. Temperature sensing probes T1 to T8 are correspondingly installed on the contact posts of contactors K1 to K8. Charging port 1, contactors K1 to K4, temperature sensing probes T1 to T4, and the electrical components forming the circuit constitute charging circuit 1. Charging port 2, contactors K5 to K8, temperature sensing probes T5 to T8, and the electrical components forming the circuit constitute charging circuit 2. The charging control method includes the following steps: Step 1: Initialize system configuration; Step 2: The BMS determines whether it is in charging mode. If yes, proceed to Step 3; otherwise, wait. Step 3: The detection and processing module detects the sampled values ​​of the temperature sensor in real time, converts them into corresponding temperature values, and sends them to the BMS; Step 4: After the BMS obtains the temperature value, it queries the table of contact temperature and allowable continuous overcurrent capacity to obtain the real-time allowable continuous overcurrent capacity value of each contactor. Step 5: BMS determines whether it is a dual-gun asynchronous configuration. If yes, proceed to step 6; otherwise, proceed to step 7. Step Six: The BMS adjusts the requested charging current of each branch in real time, and then executes Step Eight; where, the requested current of charging circuit one = min (real-time allowable charging capacity of the battery system of charging circuit one, 2 × allowable continuous overcurrent capacity of the contactor of charging circuit one, and the output limit of the charging pile), and the requested current of charging circuit two = min (real-time allowable charging capacity of the battery system - requested current of charging circuit one, 2 × allowable continuous overcurrent capacity of the contactor of charging circuit two, and the output limit of the charging pile). Step 7: The BMS adjusts the system's requested charging current and proceeds to Step 8; where, single-gun mode = min(real-time allowable charging capacity of the battery system, 2 × allowable continuous overcurrent capacity of charging circuit 1 / charging circuit 2 contactors, charging pile output limit), dual-gun mode = min{real-time allowable charging capacity of the battery system, 2 × min(allowable continuous overcurrent capacity of charging circuit 1 contactor, allowable continuous overcurrent capacity of charging circuit 2 contactor), charging pile output limit}; Step 8: Determine whether the temperature difference between the contactor contacts in parallel in charging circuit 1 and charging circuit 2 exceeds the preset threshold. If so, identify that the contactor has an abnormal disconnection, issue an alarm, and stop charging. If not, return to step 5 and dynamically adjust the charging request current in real time according to the allowable overcurrent capacity corresponding to the contactor contact temperature until the charging is fully charged and the charging is stopped.

2. The charging control method as described in claim 1, characterized in that: Step one also includes setting the initial allowable continuous overcurrent capacity value of the contactor, with the initial value set by default according to the maximum allowable value.

3. The charging control method as described in claim 1, characterized in that: Step three also includes determining whether the temperature sensor is disconnected. If it is disconnected, an alarm is triggered and charging of the corresponding circuit is stopped.

4. The charging control method as described in claim 1, characterized in that: The relationship between contact temperature and allowable continuous overcurrent capacity in step four is defined experimentally. Specifically, it includes: measuring the contact temperature rise and impedance of the contactor at different ambient temperatures and currents, and defining the allowable continuous overcurrent capacity value of the contactor at different temperatures in combination with the contactor's safety threshold. Undefined intermediate values ​​are obtained using linear interpolation.

5. The charging control method as described in claim 1, characterized in that: The real-time allowable charging capacity of the battery system in the charging circuit is min(real-time charging window value of the battery system, pre-overvoltage limit value, allowable value of the circuit cable, allowable value of the circuit connector, and allowable value of the circuit socket); among which, the allowable values ​​of the circuit cable, circuit connector, and circuit socket are related to the vehicle design and are defined after the vehicle model is finalized; the real-time charging window value of the battery system is a lookup value, that is, the allowable charging current value of the power battery pack itself corresponding to the current SOC and current cell temperature; the pre-overvoltage limit value is the allowable charging current value under different single cell voltages set by the BMS to prevent battery overcharging.

6. The charging control method as described in claim 1, characterized in that: The continuous overcurrent capability of the charging circuit contactor is the minimum value among the continuous overcurrent capabilities corresponding to the contact temperatures of all contactors in the charging circuit.

7. An electric vehicle, characterized in that: It includes the vehicle body, the power battery, and the contactor anomaly identification device as described in claim 1.

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