Contactor abnormity identification device, charging control method and electric vehicle

Abstract

The invention discloses a contactor abnormity identification device, a charging control method and an electric vehicle, and belongs to the technical field of new energy vehicle charging management. The contactor abnormity identification device comprises at least one charging port, at least one contactor, a temperature sensing probe and a detection processing module, the positive pole output end and the negative pole output end of the power battery are respectively connected with at least one group of contactors in parallel, and the other ends of each group of contactors are connected through a busbar. Each charging port is connected with the busbar through a high-voltage cable. A temperature sensing probe is arranged on a contact pole of each contactor, and the detection processing module is connected with the temperature sensing probes through signal lines. The two-dimensional current-limiting table is formed by detecting the temperature on the contact of the contactor in real time and the relation between the temperature and the current, the charging current is adjusted or charging is stopped in time, the problem that charging potential safety hazards exist due to the fact that the actual state of the contactor cannot be obtained under the shunt mode of the parallel contactor is effectively solved, and the reliability and safety of a charging system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicle charging management, and more specifically to a contactor abnormality identification device, a charging control method, and an electric vehicle. Background Art

[0002] With the rapid development and popularization of new energy vehicles, the charging experience has become a key factor restricting the development of electric vehicles, especially the charging speed of commercial vehicles with large battery configurations. Currently, the DC charging speed of electric vehicles with a single charger is typically 250A, and that of dual chargers is 400A. However, with the increase in battery capacity and charge rate, as well as the introduction of liquid-cooled supercharging stations, the demand for charging power for electric vehicles continues to increase. The maximum single-charger DC charging capacity has exceeded 1000A, placing higher requirements on the voltage and current withstand capability of the electrical components in the charging circuit.

[0003] A common approach is to increase the overcurrent capacity of the charging contactor to carry the charging current required for supercharging. However, this approach often results in larger contactors, high costs, and poor compatibility. Another approach is to use parallel shunt contactors with auxiliary contacts. For example, for a 1000A charging current, two 600A contactors are connected in parallel. Ideally, each contactor distributes 500A of current. However, the reliability of the auxiliary contacts is poor. If the auxiliary contacts mistakenly judge the contactor to be closed (when it is actually open), the parallel contactor will need to carry the entire current. Prolonged overcurrent can damage it, and connected electrical components, such as copper busbars, may also suffer safety hazards such as overheating and ablation. Summary of the Invention

[0004] The present invention provides a contactor abnormality identification device, a charging control method and an electric vehicle, aiming to solve the above shortcomings of the charging contactor of the existing electric vehicle.

[0005] The present invention adopts the following technical solutions: A contactor abnormality identification device includes a charging port, contactor 1, contactor 2, a temperature probe and a detection and processing module. The positive output end of the power battery is connected in parallel with at least one group of contactor 1, each group of contactor 1 includes at least two parallel contactors 1, and the other end of each group of contactor 1 is connected through bus 1; the negative output end of the power battery is correspondingly connected in parallel with at least one group of contactor 2, each group of contactor 2 includes at least two parallel contactors 2, and the other end of each group of contactor 2 is connected through bus 2; there is at least one charging port, and each charging port is connected to a bus 1 and a bus 2 respectively through a high-voltage cable; a temperature probe is provided on the contact pole of each contactor 1 and the contact pole of each contactor 2, and the detection and processing module is connected to the temperature probes respectively through signal lines to detect the sampling values ​​of each temperature probe in real time. The detection and processing module is also connected to the BMS through the signal line.

[0006] In a preferred embodiment, the busbar 1 is connected to the contact pole of the contactor 1 nearby; and the busbar 2 is connected to the contact pole of the contactor 2 nearby.

[0007] In a preferred embodiment, there are two charging ports, including charging port 1 and charging port 2; the positive output end of the power battery is connected in parallel with contactors K1, K2, K5, and K6, and the negative output end of the power battery is connected in parallel with contactors K3, K4, K7, and K8, and temperature probes T1 to T8 are correspondingly provided on the contact poles of contactors K1 to K8; charging port 1, contactors K1 to K4, temperature probes T1 to T4, and circuit connection electrical components constitute charging circuit 1, and charging port 2, contactors K5 to K8, temperature probes T5 to T8, and circuit connection electrical components constitute charging circuit 2.

[0008] The present invention also provides a charging control method, which uses the above-mentioned contactor abnormality identification device and includes the following steps: Step 1: Initialize system configuration; Step 2: BMS determines whether it is in charging mode. If so, it executes step 3. If not, it waits. Step 3: The detection and processing module detects the sampled value of the temperature sensor in real time and converts it into the corresponding temperature value, which is then sent to the BMS. Step 4: After the BMS obtains the temperature value, it queries the table of the relationship between the contact temperature and the 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 so, it executes step 6; otherwise, it executes step 7. Step 6: The BMS adjusts the requested charging current of each branch in real time and executes Step 8; where the requested current of charging circuit 1 = min (the real-time allowed charging capacity of the battery system for charging circuit 1, 2 * the allowed continuous overcurrent capacity of the contactor for charging circuit 1, and the output limit of the charging pile), and the requested current of charging circuit 2 = min (the real-time allowed charging capacity of the battery system - the requested current of charging circuit 1, 2 * the allowed continuous overcurrent capacity of the contactor for charging circuit 2, and the output limit of the charging pile). Step 7: The BMS adjusts the system-requested charging current and executes Step 8; where single-charger mode = min (battery system real-time allowed charging capacity, 2*the allowed continuous overcurrent capacity of the charging circuit contactor, and the charging pile output limit); dual-charger mode = min {battery system real-time allowed charging capacity, 2*min (charge circuit 1 contactor allowed continuous overcurrent capacity, charge circuit 2 contactor allowed continuous overcurrent capacity), and the charging pile output limit}; Step 8: Determine whether the temperature difference of the contact points of the parallel contactors in each charging circuit exceeds a preset threshold. If so, identify that the contactor may be abnormally disconnected, 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 contact temperature of the contactor until the charging is fully charged and the charging is terminated.

[0009] Furthermore, the above step 1 also includes setting an initial allowable continuous overcurrent capacity value of the contactor, and the initial value is set according to the maximum allowable value by default.

[0010] Furthermore, the above step three also includes determining whether the temperature sensor is offline. If offline, an alarm is issued and charging of the corresponding circuit is stopped.

[0011] Preferably, the relationship table between the contact temperature and the allowable continuous overcurrent capacity in the above step 4 is defined through experiments, 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, wherein undefined intermediate values ​​are obtained by linear interpolation.

[0012] Preferably, the real-time allowable charging capacity of the battery system in the charging circuit 1 is min(battery system real-time charging window value, pre-overvoltage limit value, loop cable allowable value, loop connector allowable value, loop socket allowable value); wherein, the loop cable allowable value, loop connector allowable value, and loop socket allowable value are related to the vehicle model design and are defined after the vehicle model is finalized; the battery system real-time charging window value is a table lookup value, that is, the charging current value allowed by the power battery pack itself corresponding to the current SOC and current battery 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.

[0013] Preferably, the allowed continuous overcurrent capacity of the charging circuit contactor is the minimum value of the allowed continuous overcurrent capacity corresponding to the contact point temperatures of all contactors on the charging circuit.

[0014] The present invention also provides an electric vehicle, comprising a vehicle body, a power battery and a contactor abnormality identification device.

[0015] It can be seen from the above description of the present invention that, compared with the prior art, the present invention has the following advantages: 1. The present invention integrates a temperature sensor on the contact pole of the contactor. By real-time detection of the temperature on the contactor and its relationship with the current, a two-dimensional current limiting table is formed. Abnormal problems of parallel contactors can be discovered in time, 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 status of the contactor in the shunt mode of parallel contactors, thereby improving the reliability and safety of the charging system.

[0016] 2. The present invention identifies contactor abnormalities based on contact temperature, without increasing the contactor volume or adding auxiliary contacts. It has high reliability, low cost, and good compatibility, overcoming the shortcomings of traditional solutions such as large volume, high cost, and poor compatibility.

[0017] 3. The charging control method of the present invention enables the BMS to dynamically adjust the charging current according to different configuration requirements, thereby achieving flexibility in the charging strategy and improving charging efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of a contactor abnormality identification device according to an embodiment of the present invention.

[0019] Figure 2 This is a flow chart of a charging control method according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0020] Refer to the following Figure 1 The following describes specific embodiments of the present invention. Numerous details are provided below to provide a comprehensive understanding of the present invention, but those skilled in the art will appreciate that the present invention can be implemented without these details. Well-known components, methods, and processes are not described in detail below.

[0021] Example 1 This embodiment provides a contactor anomaly identification device, including a charging port, multiple contactors, a temperature sensor, and a detection and processing module. To facilitate the explanation of the principle, this embodiment provides a dual charging port and dual contactors in parallel.

[0022] Reference Figure 1There are two charging ports, including 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.

[0023] The charging port 1 is connected to the busbars connected to contactors K1 and K2 and the busbars connected to contactors K3 and K4 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 via high-voltage cables.

[0024] The above busbars are connected to the contact poles of the contactor as close as possible, that is, the connection position between the busbar and the contactor is as close as possible to the contact poles of the contactor to minimize the impact of unequal impedance of the line copper busbar or cable assembly and prevent overcurrent of the contactor.

[0025] The contact poles of contactors K1 through K8 are each equipped with temperature sensors T1 through T8. A detection and processing module is connected to each of these sensors via signal lines to monitor the sampled values ​​from each sensor in real time. This detection and processing module is also connected to the battery management system (BMS) via signal lines. Based on the sampled temperature values, the BMS uses a table to determine the overcurrent capacity of each contactor, making a comprehensive assessment of the system's overcurrent capacity and requesting a safe charging current from the charging station.

[0026] Although the above embodiment only shows the form of dual charging ports and dual contactors connected in parallel, the solution of the present invention is also applicable to the form of more than two charging ports and more than two contactors connected in parallel.

[0027] Example 2 This embodiment provides a charging control method, using the above-mentioned contactor abnormality identification device, referring to Figure 2 , including the following steps: Step 1: Initialize system configuration.

[0028] Step 2: BMS determines whether it is in charging mode. If so, it executes step 3. If not, it waits.

[0029] Step 3: The detection and processing module detects the sampling values ​​of temperature sensors T1 to T8 in real time and converts them into corresponding temperature values, which are then sent to the BMS.

[0030] Step 4: After the BMS obtains the temperature value, it queries the table of the relationship between the contact temperature and the allowable continuous overcurrent capacity to obtain the real-time allowable continuous overcurrent capacity value of each contactor.

[0031] Step 5: BMS determines whether it is a dual-gun asynchronous configuration. If so, it executes step 6; otherwise, it executes step 7.

[0032] Step 6: The BMS adjusts the requested charging current of each branch in real time and executes step 8; wherein, the requested current of charging circuit 1 = min (the real-time allowed charging capacity of the battery system for charging circuit 1, 2*the allowed continuous overcurrent capacity of the contactor for charging circuit 1, and the output limit of the charging pile), and the requested current of charging circuit 2 = min (the real-time allowed charging capacity of the battery system - the requested current of charging circuit 1, 2*the allowed continuous overcurrent capacity of the contactor for charging circuit 2, and the output limit of the charging pile).

[0033] Step 7: The BMS adjusts the system-requested charging current and executes step 8; where single-gun mode = min (battery system's real-time allowed charging capacity, 2*the charging circuit contactor's allowed continuous overcurrent capacity, charging pile output limit), dual-gun mode = min {battery system's real-time allowed charging capacity, 2*min (charging circuit 1 contactor's allowed continuous overcurrent capacity, charging circuit 2 contactor's allowed continuous overcurrent capacity), charging pile output limit}.

[0034] Step 8: Determine whether the temperature difference of the contact points of the parallel contactors in each charging circuit exceeds a preset threshold. If so, identify that the contactor may be abnormally disconnected, 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 contact temperature of the contactor until the charging is fully charged and the charging is terminated.

[0035] The above step 1 also includes setting the initial allowable continuous overcurrent capacity value of the contactor. The initial value is set by default 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.

[0036] The above step 3 also includes determining whether the temperature sensor is offline. If offline, an alarm is issued and charging of the corresponding circuit is stopped.

[0037] The relationship between contact temperature and allowable continuous overcurrent capacity in step 4 above was defined through experimentation. Specifically, the contactor's contact temperature rise and impedance were measured at different ambient temperatures and currents. The contactor's allowable continuous overcurrent capacity at different temperatures was then defined based on the contactor's safety thresholds. Undefined intermediate values ​​were obtained using linear interpolation. For example, in Table 1 below, the current contactor contact temperature is 112°C, corresponding to an allowable continuous overcurrent capacity of 280A. Temperature / ℃ ≤110 115 120 125 130 ≥135 Allowable current / A 300 250 200 150 100 0

[0038] Table 1 Relationship between contact temperature and allowable continuous overcurrent capacity The above dual-gun asynchronous configuration means that the vehicle is equipped with dual charging ports. The two charging ports are independent of each other. The vehicle can be charged independently through two piles without affecting each other. The charging request current of each charging port is also an independent request.

[0039] The above-mentioned charging circuit 1 includes a charging port 1, contactors K1-K4, temperature probes T1-T4 and circuit connection electrical components; the charging circuit 2 includes a charging port 2, contactors K5-K8, temperature probes T5-T8 and circuit connection electrical components.

[0040] The real-time allowable charging capacity of the battery system in the above-mentioned charging loop 1 = min (battery system real-time charging window value, pre-overvoltage limit value, loop cable allowable value, loop connector allowable value, loop socket allowable value); among them, the loop cable allowable value, loop connector allowable value and loop socket allowable value are related to the vehicle model design, and the values ​​are defined after the vehicle model is finalized; the battery system real-time charging window value is a table lookup value, that is, the charging current value allowed by the power battery pack itself corresponding to the current SOC and current battery cell temperature; the pre-overvoltage limit value is the charging current value allowed under different single cell voltages set by the BMS to prevent battery overcharging.

[0041] The above allowed values ​​for charging piles are the output limits sent by the charging piles to the BMS.

[0042] The allowable continuous overcurrent capacity of the charging circuit contactor is the minimum value of the allowable continuous overcurrent capacity corresponding to the contact point temperatures of all contactors in the charging circuit.

[0043] The above are the specific steps of this embodiment. By real-time detection of the temperature on the contactor contacts and its relationship with the current, abnormal problems of the parallel contactors can be discovered in time, and the charging current can be adjusted or charging can be stopped in time, effectively solving the problem of charging safety hazards caused by the inability to obtain the actual state of the contactor under the parallel contactor shunt mode, and improving the safety of the charging system; adopting the abnormality identification method based on contact temperature, there is no need to increase the size of the contactor or add auxiliary contacts, with high reliability, low cost, and good compatibility, overcoming the shortcomings of large size, high cost and poor compatibility in traditional solutions.

[0044] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A contactor abnormality identification device, characterized in that: It includes a charging port, contactor 1, contactor 2, a temperature probe and a detection and processing module. The positive output end of the power battery is connected in parallel with at least one group of contactor 1, each group of contactor 1 includes at least two parallel contactors 1, and the other end of each group of contactor 1 is connected through bus 1; the negative output end of the power battery is correspondingly connected in parallel with at least one group of contactor 2, each group of contactor 2 includes at least two parallel contactors 2, and the other end of each group of contactor 2 is connected through bus 2; there is at least one charging port, and each charging port is connected to a bus 1 and a bus 2 through a high-voltage cable; a temperature probe is provided on the contact pole of each contactor 1 and the contact pole of each contactor 2, and the detection and processing module is connected to the temperature probes respectively through signal lines to detect the sampling values ​​of each temperature probe in real time. The detection and processing module is also connected to the BMS through a signal line.

2. The contactor abnormality identification device according to claim 1, characterized in that: The busbar 1 is connected to the contact pole of the contactor 1 nearby; the busbar 2 is connected to the contact pole of the contactor 2 nearby.

3. The contactor abnormality identification device according to claim 1 or 2, characterized in that: There are two charging ports, including charging port 1 and charging port 2; the positive output end of the power battery is connected in parallel with contactors K1, K2, K5, and K6, and the negative output end of the power battery is connected in parallel with contactors K3, K4, K7, and K8. Temperature probes T1 to T8 are correspondingly provided on the contact poles of contactors K1 to K8; charging port 1, contactors K1 to K4, temperature probes T1 to T4, and circuit connection electrical components constitute charging circuit 1, and charging port 2, contactors K5 to K8, temperature probes T5 to T8, and circuit connection electrical components constitute charging circuit 2.

4. A charging control method, characterized in that: The contactor abnormality identification device according to claim 3 comprises the following steps: Step 1: Initialize system configuration; Step 2: BMS determines whether it is in charging mode. If so, it executes step 3. If not, it waits. Step 3: The detection and processing module detects the sampled value of the temperature sensor in real time and converts it into the corresponding temperature value, which is then sent to the BMS. Step 4: After the BMS obtains the temperature value, it queries the table of the relationship between the contact temperature and the 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 so, it executes step 6; otherwise, it executes step 7. Step 6: The BMS adjusts the requested charging current of each branch in real time and executes Step 8; where the requested current of charging circuit 1 = min (the real-time allowed charging capacity of the battery system for charging circuit 1, 2 * the allowed continuous overcurrent capacity of the contactor for charging circuit 1, and the output limit of the charging pile), and the requested current of charging circuit 2 = min (the real-time allowed charging capacity of the battery system - the requested current of charging circuit 1, 2 * the allowed continuous overcurrent capacity of the contactor for charging circuit 2, and the output limit of the charging pile). Step 7: The BMS adjusts the system-requested charging current and executes Step 8; where single-charger mode = min (battery system real-time allowed charging capacity, 2*the allowed continuous overcurrent capacity of the charging circuit contactor, and the charging pile output limit); dual-charger mode = min {battery system real-time allowed charging capacity, 2*min (charge circuit 1 contactor allowed continuous overcurrent capacity, charge circuit 2 contactor allowed continuous overcurrent capacity), and the charging pile output limit}; Step 8: Determine whether the temperature difference of the contact points of the parallel contactors in each charging circuit exceeds a preset threshold. If so, identify that the contactor may be abnormally disconnected, 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 contact temperature of the contactor until the charging is fully charged and the charging is terminated.

5. The charging control method according to claim 4, wherein: The step 1 also includes setting an initial allowable continuous overcurrent capacity value of the contactor, and the initial value is set according to the maximum allowable value by default.

6. The charging control method according to claim 4, wherein: The step three also includes determining whether the temperature sensor is offline. If offline, an alarm is triggered and charging of the corresponding circuit is stopped.

7. The charging control method according to claim 4, wherein: The relationship table between the contact temperature and the allowable continuous overcurrent capacity in step 4 is defined through experiments, 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. Undefined intermediate values ​​are obtained by linear interpolation.

8. The charging control method according to claim 4, wherein: The real-time allowable charging capacity of the battery system in charging loop 1 = min (battery system real-time charging window value, pre-overvoltage limit value, loop cable allowable value, loop connector allowable value, loop socket allowable value); among which, the loop cable allowable value, loop connector allowable value, and loop socket allowable value are related to the vehicle model design and are defined after the vehicle model is finalized; the battery system real-time charging window value is a table lookup value, that is, the charging current value allowed by the power battery pack itself corresponding to the current SOC and current battery cell temperature; the pre-overvoltage limit value is the charging current value allowed under different single cell voltages set by the BMS to prevent battery overcharging.

9. The charging control method according to claim 4, wherein: The allowed continuous overcurrent capacity of the charging circuit contactor is the minimum value of the allowed continuous overcurrent capacity corresponding to the contact point temperatures of all contactors on the charging circuit.

10. An electric vehicle, characterized in that: It comprises a vehicle body, a power battery and the contactor abnormality identification device as claimed in claim 1.

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