CN117607676A

CN117607676A - Relay adhesion detection method, circuit and vehicle

Info

Publication number: CN117607676A
Application number: CN202311607381.5A
Authority: CN
Inventors: 喻婷; 冯佩云; 夏凯
Original assignee: Dongfeng Motor Group Co Ltd
Current assignee: Dongfeng Motor Group Co Ltd
Priority date: 2023-11-27
Filing date: 2023-11-27
Publication date: 2024-02-27

Abstract

The embodiment of the disclosure provides a relay adhesion detection method and circuit and a vehicle. The relay comprises a first end and a second end, wherein the first end is used for being connected with the charging interface, and the second end is used for being connected with the battery pack; the relay adhesion detection method comprises the following steps: sampling the first voltage of the first terminal and the second voltage of the second terminal of the relay a plurality of times during the voltage of the first terminal of the relay increases to the precharge voltage; determining a plurality of first actual pressure differences corresponding to the relay at a plurality of sampling moments according to the first voltage and the second voltage which are sampled for a plurality of times; comparing the plurality of first actual pressure differences with a first threshold pressure difference to obtain a plurality of comparison results; and judging whether the relay is in an off state according to a plurality of comparison results.

Description

Relay adhesion detection method, circuit and vehicle

Technical Field

The disclosure relates to the technical field of electric automobiles, in particular to a relay adhesion detection method, a relay adhesion detection circuit and a relay adhesion detection vehicle.

Background

In recent years, the country is strongly supporting the development of new energy electric vehicles in consideration of multiple factors such as energy safety and environmental protection. The battery system is a core component of an electric automobile, and the reliability of the battery system directly affects the safety and reliability of the whole automobile. Battery systems are high voltage and high current applications that typically use a relay as a switch to control the on and off of a charging circuit. However, due to long-time use or use environment of high voltage and high current, the relay may have adhesion phenomenon, so that the charging loop is uncontrollable, and some safety accidents may be caused. Therefore, the adhesion detection work for the relay is necessary.

Disclosure of Invention

According to a first aspect of the present disclosure, there is provided a relay adhesion detection method, the relay including a first end for connecting a charging interface and a second end for connecting a battery pack; the method comprises the following steps:

sampling a first voltage at a first terminal and a second voltage at a second terminal of the relay multiple times during a rise in the voltage at the first terminal of the relay to a precharge voltage;

determining a plurality of first actual pressure differences corresponding to the relay at a plurality of sampling moments according to the first voltage and the second voltage which are sampled for a plurality of times; comparing the plurality of first actual pressure differences with a first threshold pressure difference to obtain a plurality of comparison results;

and judging whether the relay is in an off state according to the comparison results.

In some embodiments, the determining a plurality of first actual differential pressures of the relay at a plurality of sampling moments according to the first voltage and the second voltage sampled a plurality of times includes:

an absolute value of a difference between the first voltage and the second voltage for each sampling is obtained as the first actual differential pressure of the relay.

In some embodiments, the determining whether the relay is in an open state according to the plurality of comparison results includes:

if the comparison results indicate that at least one first actual pressure difference is larger than or equal to the first threshold pressure difference, judging that the relay is in a disconnection state;

and if the comparison results indicate that the actual differential pressures are smaller than the first threshold differential pressure, judging that the relay is adhered.

In some embodiments, the charging operation process of the battery pack comprises a handshake phase, a parameter configuration phase, a charging phase and a charging end phase;

determining a plurality of first actual pressure differences corresponding to the relay at a plurality of sampling moments according to the first voltage and the second voltage which are sampled for a plurality of times; comparing the plurality of first actual differential pressures with a first threshold differential pressure to obtain a plurality of comparison results, including:

determining the first actual pressure difference of the relay at the sampling time according to the first voltage and the second voltage sampled each time during the period from the first time when the first instruction is received to the second time when the second instruction is received; comparing the first actual pressure difference with a first threshold pressure difference to obtain a comparison result;

The first instruction indicates the charging operation process to perform a parameter configuration stage, and the voltage of the first end of the relay starts to rise; the second instruction indicates that the voltage of the first terminal of the relay reaches the precharge voltage.

In some embodiments, the sampling the first voltage at the first terminal and the second voltage at the second terminal of the relay multiple times during the step-up of the voltage at the first terminal of the relay to the precharge voltage comprises:

in response to the first instruction, beginning to sample the first voltage and the second voltage; stopping sampling the first voltage and the second voltage in response to the second instruction; or,

the first voltage and the second voltage are sampled throughout the charging operation.

In some embodiments, the first instruction is a charging pile identification message; and/or the number of the groups of groups,

the second instruction is a maximum output capacity message of the charging pile.

In some embodiments, the method further comprises:

maintaining the second end of the relay in a conducting state with the battery pack during a charging end period, and disconnecting the relay;

sampling a third voltage at a first end and a fourth voltage at a second end of the relay;

Determining a second actual differential pressure of the relay based on the third voltage and the fourth voltage;

and comparing the second actual pressure difference with a second threshold pressure difference, and judging whether the relay is in a disconnection state according to a comparison result.

According to a second aspect of the present disclosure, there is provided a relay adhesion detection circuit including:

the relay comprises a first end and a second end, wherein the first end is used for being connected with a charging interface, and the second end is used for being connected with a battery pack;

a sampling circuit, coupled to the first and second ends of the relay, configured to: sampling a first voltage at a first terminal and a second voltage at a second terminal of the relay multiple times during a rise in the voltage at the first terminal of the relay to a precharge voltage;

a battery management system, coupled to the sampling circuit, configured to: determining a plurality of first actual pressure differences corresponding to the relay at a plurality of sampling moments according to the first voltage and the second voltage which are sampled for a plurality of times; comparing the plurality of first actual pressure differences with a first threshold pressure difference to obtain a plurality of comparison results; judging whether the relay is adhered or not according to the comparison results.

In some embodiments, the battery management system is configured to:

In some embodiments, the charging operation process of the battery pack comprises a handshake phase, a parameter configuration phase, a charging phase and a charging end phase; the battery management system is configured to:

In some embodiments, the battery management system is further configured to:

and comparing the second actual pressure difference with a second threshold pressure difference, and judging whether the relay is adhered or not according to a comparison result.

In some embodiments, the relay is a fast charge positive relay or a fast charge negative relay.

According to a third aspect of the present disclosure there is provided a vehicle comprising a relay adhesion detection circuit as in any of the second aspects of the present disclosure.

In the embodiment of the disclosure, the first end of the relay is used for being connected with the charging interface, the second end of the relay is used for being connected with the battery, and the relay is normally in an off state before the charging stage. During the precharge operation of the charge stake to gradually increase the voltage of the charge interface from the low voltage (e.g., 0V) to the precharge voltage, the voltage of the first end of the relay is also gradually increased from the low voltage to the precharge voltage in synchronization. If the first and second terminals of the relay are stuck, the voltages at the first and second terminals of the relay are varied simultaneously such that the first actual differential pressure between the first and second terminals remains substantially unchanged. If the first end and the second end of the relay are not adhered, the relay is normally in an off state, the voltage of the first end and the voltage of the second end of the relay are not changed synchronously, and the first actual pressure difference of the first end and the second end of the relay can be gradually increased or gradually reduced along with the voltage of the first end to the precharge voltage. In the embodiment of the disclosure, by comparing the plurality of first actual differential pressures obtained by sampling for a plurality of times with the first threshold differential pressure, the change condition of the first actual differential pressures of the first end and the second end of the relay along with the rise of the voltage of the first end to the precharge voltage can be judged, so that whether the relay is adhered or not can be judged. And once the adhesion is judged, the charging is finished in time, and the reporting fault is diagnosed, so that the high-voltage potential safety hazard is avoided.

Drawings

Fig. 1 is a block diagram of an electric control system of a domestic electric vehicle meeting an euro-standard charging protocol according to an embodiment of the present disclosure;

fig. 2 is a schematic circuit diagram of an electric control system of a domestic electric vehicle meeting an euro standard charging protocol according to an embodiment of the present disclosure;

fig. 3 is a schematic flow chart of a first adhesion detection of a relay according to an embodiment of the disclosure;

fig. 4 is a schematic diagram of a battery system according to an embodiment of the present disclosure;

fig. 5 is an interactive flowchart of performing standard dc fast charging on a domestic electric vehicle according to an embodiment of the disclosure;

fig. 6 is a schematic flow chart of a second adhesion detection of a relay according to an embodiment of the disclosure;

fig. 7 is a schematic diagram of a relay adhesion detection circuit according to an embodiment of the disclosure.

Detailed Description

The technical scheme of the present disclosure will be further elaborated with reference to the drawings and examples. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. In the following description, the present disclosure presents numerous specific details in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present disclosure may be practiced without one or more of these details.

The present disclosure may understand terminology based, at least in part, on usage in the context. For example, the term "one or more" as used herein may be used to describe any feature, structure, or characteristic in a singular sense or may be used to describe combinations of features, structures, or characteristics in a plural sense. Similarly, terms such as "a" or "an" may be equally understood as conveying a singular usage or a plural usage. In addition, the term "based on" may be understood as not necessarily intended to convey an exclusive set of factors, and may instead allow for the presence of additional factors that are not necessarily explicitly described. The terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The term "and/or" includes any and all combinations of the associated listed items.

The technical solutions described in the embodiments of the present disclosure may be arbitrarily combined without any conflict.

One of the problems faced by the domestic new energy electric automobile in the army European market includes the charging problem of the electric automobile. At present, the domestic electric automobile charging protocol uses GB/T27930, adopts CAN (Controller Area Network ) bus communication, and is not matched with a charging pile using European standard charging protocol. The charging protocol used in europe is a Combined charging system (Combined ChargingSystem, CCS), and CCS uses PLC (Power Line Communication) communication.

One solution is to add a controller with a communication protocol conversion function, i.e., an electric vehicle communication controller (Electric Vehicle Communication Controller, EVCC), to an electric vehicle. Fig. 1 is a block diagram of an electric control system of a domestic electric automobile meeting the standard european charging protocol, as shown in fig. 1, information between a charging pile 100 and a battery management system (Battery Management System, BMS) 220 is forwarded through an EVCC 210, and the EVCC 210 and the BMS220 interact according to the standard fast charging protocol, and a CAN communication mode is adopted. The EVCC 210 performs PLC communication with the charging pile 100. The EVCC 210 converts the european standard charging protocol into the national standard GBT 27930 charging protocol and interacts with the BMS220, and the corresponding message timeout judgment in the interaction process is adjusted in consideration of the information processing forwarding time, so as to realize the charging function of the electric vehicle.

Fig. 2 is a schematic circuit diagram of an electric control system of a domestic electric vehicle satisfying the euro standard charging protocol, and as shown in fig. 2, a quick charging port between the electric vehicle specified by the euro standard and the charging pile 100 includes: CP (Control Pilot) interface, PP (proximity Pilot) interface, PE (produced Earth guard) interface, dc+ interface, DC-interface, etc. The CP interface transmits PWM signals for PLC communication. The PP interface transmits signals so that the electric automobile can monitor that the charging gun plug is connected. The PE interface is a ground protection, and is the ground lead of the device. The DC+ interface and the DC-interface are used for providing a direct current power supply for direct current quick charging.

With continued reference to fig. 2, the entire vehicle provides 12V normal electricity to the EVCC 210 as an auxiliary source, and the EVCC 210 wakes up the BMS220 through an a+ hard wire. After receiving the signals transmitted by the charging pile 100 through the CP interface and the PP interface, the EVCC 210 converts the signals into CAN1 signals (i.e., fast charging CAN signals) and CC2 signals that satisfy the national standard fast charging protocol GB/T27930 to interact with the BMS220, and converts the signals into CCOUT signals and CPOUT signals to interact with the OBC (On Board Charger) 230. For example, message interaction in the charging process is performed between the EVCC 210 and the BMS220 through the CAN1 bus. The CC2 signal is a signal that the BMS220 determines that the charging gun and the charging pile 100 are connected. CCOUT is a charge connection acknowledge signal line connected to OBC 230. CPOUT is a charge control line connected to OBC 230 for communication with charging peg 100 via EVCC 210. In addition, the EVCC 210 may also be connected to a complete vehicle CAN bus through a CAN2 bus to interact with a complete vehicle controller (Vehicle Control Unit, VCU) in a signal manner. The BMS220 and the OBC 230 may also interact with the vehicle controller via the vehicle CAN bus.

The national standard quick charging protocol GB/T27930 is used for restraining a detailed standard flow for high-voltage control and discharging of a domestic charging pile, and the BMS at the electric automobile end performs adhesion diagnosis of the quick charging relay at the automobile end after the charging pile finishes high-voltage discharging and sends a corresponding message. When adhesion diagnosis is carried out on the fast charging relay, the front end of the fast charging relay, which is close to the battery pack, is high-voltage, and the rear end voltage, which is close to the fast charging interface, is 0V. The fast charging relay is normally in an off state, and if adhesion occurs, the voltage at the rear end is also increased to high voltage. In general, whether or not sticking occurs in the quick charge relay is determined by determining whether or not the voltage of the rear end is equal to or greater than 0.X times (e.g., 0.9 times) the voltage of the front end.

The European standard charging pile is different from the national standard charging pile, and in the early interaction stage (such as the parameter configuration stage corresponding to the national standard), the charging pile performs pre-charging according to the parameter configuration information sent by the BMS forwarded by the EVCC, and the high voltage of the charging pile is established. If the adhesion diagnosis of the BMS for the quick charging relay is kept consistent with the national standard quick charging process, the adhesion fault of the relay is misreported and the quick charging cannot be performed. It can be understood that the European standard charging pile is pre-charged in the parameter configuration stage, so that the voltage at the rear end of the quick charging relay is increased, the pressure difference at the front end and the rear end of the quick charging relay can possibly meet the adhesion judgment condition, but the actual quick charging relay is not necessarily adhered, and therefore, the adhesion of the false alarm relay can possibly occur, the quick charging cannot be caused, and hidden danger can be brought to the safety of the whole vehicle. Therefore, the adhesion diagnosis strategy of the fast charging relay needs to be adjusted aiming at European standard direct current fast charging.

Fig. 3 is a schematic flow chart of a method for detecting adhesion of a relay according to an embodiment of the present disclosure, where, as shown in fig. 3, the method for detecting adhesion of a relay satisfying the euler direct current fast charging includes: performing a first stuck detection on the relay during a voltage rise of the first end of the relay to the precharge voltage; wherein performing a first adhesion test comprises:

S110: sampling the first voltage of the first terminal and the second voltage of the second terminal of the relay a plurality of times during the voltage of the first terminal of the relay increases to the precharge voltage;

s120: determining a plurality of first actual pressure differences corresponding to the relay at a plurality of sampling moments according to the first voltage and the second voltage which are sampled for a plurality of times; comparing the plurality of first actual pressure differences with a first threshold pressure difference to obtain a plurality of comparison results;

s130: and judging whether the relay is in an off state according to a plurality of comparison results.

In some embodiments, if the second terminal of the relay is in conduction with the positive pole of the battery, the voltage at the second terminal of the relay is equal to the positive pole voltage of the battery and greater than or equal to the precharge voltage, then the first actual differential pressure between the first terminal and the second terminal of the relay gradually decreases as the voltage at the first terminal of the relay increases to the precharge voltage. If the second terminal of the relay is disconnected from the battery pack, the voltage of the second terminal of the relay is 0V, and the first actual voltage difference between the first terminal and the second terminal of the relay gradually increases as the voltage of the first terminal of the relay increases to the precharge voltage. That is, when the relay is in the normal off state, no matter whether the second terminal is conducted with the battery pack, the first actual voltage difference of the relay is greatly changed (or gradually increased or gradually decreased) along with the voltage of the first terminal of the relay rising to the precharge voltage, so that the relay can be judged to be in the normal working state. Whether the second end of the relay is in a conducting state or a disconnecting state with the battery pack, if the relay is adhered, the voltage of the first end and the voltage of the second end of the relay synchronously change, so that the first actual pressure difference is small, and the adhesion of the relay can be judged. In other words, the adhesion detection method of the relay provided by the embodiment is suitable for the state that the second end of the relay is in conduction with the battery pack, and is also suitable for the state that the second end of the relay is in disconnection with the battery pack.

In some embodiments, when the whole vehicle is in an ON gear, an electric component in the vehicle is powered ON, a second end of the relay is in a conducting state with the battery pack, when the whole vehicle is in an OFF gear, the vehicle is powered OFF, and the second end of the relay is in a disconnecting state with the battery pack, namely, the relay adhesion detection method for European standard direct current fast charging, provided by the embodiment of the disclosure, can accurately and effectively diagnose whether the relay is adhered or not no matter the whole vehicle is in the ON gear or the OFF gear, and avoid false alarm faults and incapacity of charging.

In some embodiments, in step S120, determining a plurality of first actual differential pressures of the relay corresponding to a plurality of sampling moments according to the first voltage and the second voltage sampled a plurality of times includes:

As shown above, when the whole vehicle is in the ON range, the second voltage at the second end of the fast charge positive relay is the positive voltage of the battery pack, resulting in a negative difference between the first voltage and the second voltage of the fast charge positive relay. And when the whole vehicle is in an OFF gear, the second voltage of the fast charge positive relay is 0V, and the difference value between the first voltage and the second voltage of the fast charge positive relay is a positive value. In order to meet the requirement that the two cases share the same first threshold voltage, in this embodiment, the absolute value of the difference between the first voltage and the second voltage is taken as the first actual voltage difference across the relay, and compared with the first threshold voltage. Therefore, the judgment of the voltage of the second end of the relay and the setting of the first threshold voltage according to the situation can be avoided, and the circuit can be simplified.

In some embodiments, step S130, determining whether the relay is in an open state according to the plurality of comparison results includes:

if the comparison results indicate that at least one first actual pressure difference is larger than or equal to a first threshold pressure difference, judging that the relay is in an off state;

and if the comparison results indicate that the first actual differential pressures are smaller than the first threshold differential pressure, judging that the relay is adhered.

In connection with the above analysis, if the first and second terminals of the relay are stuck during the period when the voltage of the first terminal of the relay is raised to the precharge voltage, the relay will be changed from the normally off state to the on state, and the voltages of the first and second terminals of the relay will be changed synchronously, so that the voltage difference between the first and second terminals of the relay is substantially unchanged and is always smaller than the first threshold voltage. That is, the first actual voltage differences of the relay obtained by multiple sampling are smaller than the first threshold voltage, and the relay can be judged to be adhered.

In some embodiments, the first threshold voltage may be determined based on an actual differential pressure across the relay when different degrees of sticking occur, i.e., the first threshold voltage is made greater than or equal to the actual differential pressure across the relay when different degrees of sticking occur, to increase the sensitivity of the sticking detection.

When the voltage of the first end of the relay is increased to the precharge voltage, if the first end and the second end of the relay are not adhered, the voltage of the first end and the voltage of the second end of the relay are not changed synchronously, and as the voltage of the first end is gradually increased from the low voltage to the precharge voltage, the actual differential pressure of the first end and the second end of the relay is gradually increased or gradually decreased, so that at least one first actual differential pressure of a plurality of first actual differential pressures obtained by sampling is larger than or equal to a first threshold voltage, and the relay can be judged to be in a normal disconnection state.

In some embodiments, the first threshold voltage is 15V to 25V in magnitude. The first threshold voltage is, for example, 20V in magnitude.

Fig. 4 is a schematic diagram showing a battery system. The following details the adhesion detection process of the fast charge positive relay and the fast charge negative relay with reference to fig. 4. As shown in fig. 4, a fast charge positive relay 410 and a main positive relay 420 are connected in series between the positive electrode of the battery pack 300 and a fast charge positive electrode interface dc+, and a precharge branch is connected in parallel to both ends of the main positive relay 420, and includes a precharge relay 430 and a precharge resistor 500 connected in series. A fast charge negative relay 440 and a main negative relay 450 are connected in series between the negative pole of the battery pack 300 and the fast charge negative pole interface DC-.

The first terminal a of the fast charge positive relay 410 is connected to the fast charge positive interface dc+ and the second terminal B is connected to the main positive relay 420. The first terminal C of the fast charge negative relay 440 is connected to the fast charge negative interface DC-and the second terminal D is connected to the main negative relay 450. The sampling terminals of the sampling circuit are respectively connected with a first terminal A and a second terminal B of the fast charge positive relay 410, a first terminal C and a second terminal D of the fast charge negative relay 440, and a terminal E of the main negative relay 450, which is close to the battery pack. The end E of the main negative relay 450 near the battery pack is a high voltage detection reference point. In other words, the voltages of the four sampling points A, B, C, D obtained by the sampling circuit are the potential differences between the four sampling points and the high-voltage detection reference point, respectively.

In some embodiments, when the entire vehicle is in the ON range, the main positive relay 420 is closed and the voltage at the second terminal B of the fast charge positive relay 410 is equal to the positive voltage of the battery pack 300. When the pre-charging is performed according to the euro-standard charging pile, the position of the fast charging positive electrode interface dc+, i.e. the first end a of the fast charging positive relay 410, is a voltage in a pre-charging rising state. If the fast charge positive relay 410 is in the normal off state, the voltages at the first terminal a and the second terminal B of the fast charge positive relay 410 do not change synchronously, and as the voltage at the first terminal a gradually increases from the low voltage to the precharge voltage, the first actual differential pressure between the first terminal a and the second terminal B of the fast charge positive relay 410 gradually decreases, but at least one of the first actual differential pressures is greater than or equal to the first threshold voltage, so it can be determined that the fast charge positive relay 410 is not stuck and is in the normal off state.

In some embodiments, when the entire vehicle is in the OFF gear, the main positive relay 420 is turned OFF and the voltage at the second terminal B of the fast charge positive relay 410 is 0V. If the fast charge positive relay 410 is in the normal off state, as the voltage of the first terminal a gradually increases from the low voltage to the precharge voltage, the first actual voltage difference between the first terminal a and the second terminal B of the fast charge positive relay 410 gradually increases, and at least one first actual voltage difference is greater than or equal to the first threshold voltage, so it may also be determined that the fast charge positive relay 410 is not stuck.

Whether the whole vehicle is in the ON gear or the OFF gear, if the fast charging positive relay 410 is stuck, the voltages of the first end a and the second end B of the fast charging positive relay 410 are synchronously changed, so that the first actual pressure difference between the first end a and the second end B of the fast charging positive relay 410 is always smaller than the first threshold voltage (for example, smaller than 20V), and the fast charging positive relay 410 can be judged to be stuck.

The first end C of the fast charge negative relay 440 is connected to the fast charge negative interface DC-, and when the euro standard charging pile performs the precharge, the voltage of the fast charge negative interface DC-, that is, the voltage of the first end C of the fast charge negative relay 440 is also a voltage in a precharge rising state. I.e. the voltages of the fast charge positive electrode interface DC + and the fast charge negative electrode interface DC-are substantially equal and vary synchronously.

If the main negative relay 450 is turned on, the voltage of the second terminal D of the fast charge negative relay 440 is substantially equal to the negative voltage of the battery pack 300, and the negative voltage of the battery pack 300 is a high voltage. If the main negative relay 450 is turned off, the voltage of the second terminal D of the fast charge negative relay 440 is 0V.

The principle of adhesion judgment for the fast charge negative relay 440 is the same as that of the fast charge positive relay 410. For example, if the first terminal C and the second terminal D of the fast charge-negative relay 440 are not adhered, the voltages of the first terminal C and the second terminal D of the fast charge-negative relay 440 are not synchronously changed, and as the voltage of the first terminal C gradually increases to the precharge voltage, the first actual differential pressure of the first terminal C and the second terminal D of the fast charge-negative relay 440 gradually increases or gradually decreases, so that at least one of the first actual differential pressures obtained by sampling multiple times is greater than or equal to the first threshold voltage, and it can be determined that the fast charge-negative relay 440 is not adhered and is in a normal open state.

If the first terminal C and the second terminal D of the fast charge-negative relay 440 are stuck, the voltages of the first terminal C and the second terminal D of the fast charge-negative relay 440 will be changed synchronously, so that the pressure difference between the first terminal C and the second terminal D of the fast charge-negative relay 440 is basically unchanged and is always smaller than the first threshold voltage, and it can be determined that the fast charge-negative relay 440 is stuck.

In summary, the relay adhesion detection method provided in the embodiments of the present disclosure can perform adhesion diagnosis ON the fast charging positive relay 410 and adhesion diagnosis ON the fast charging negative relay 440, and can detect whether the whole vehicle is in the ON gear or the OFF gear by adopting a unified method, and also cannot generate false alarm faults. Once adhesion is found, charging is stopped, and faults are diagnosed and reported in time so as to eliminate high-voltage potential safety hazards.

In some embodiments, step S110, sampling the first voltage at the first terminal and the second voltage at the second terminal of the relay a plurality of times includes:

the first voltage and the second voltage are periodically sampled during a step-up of the voltage at the first end of the relay to the precharge voltage.

In other words, the voltage at the first and second terminals of the relay is sampled once every fixed interval duration during the time that the voltage at the first terminal of the relay rises to the precharge voltage. The fixed interval duration can be set smaller to increase the sampling times and improve the detection accuracy. The sampling circuit periodically and continuously samples the first voltage and the second voltage and sends the first voltage and the second voltage sampled each time to the battery management system; after receiving the first voltage and the second voltage, the battery management system obtains a first actual voltage difference based on the first voltage and the second voltage, compares the first actual voltage difference with a first threshold voltage, and outputs a comparison result. Finally, the battery management system determines whether adhesion of the relay occurs based on the plurality of comparison results.

In some embodiments, the charging operation process of the battery pack includes a handshake phase, a parameter configuration phase, a charging phase, and a charging end phase; step S120 may specifically include:

The following details the timing of performing the first adhesion detection on the relay provided in the embodiment of the present disclosure in conjunction with the interactive procedure of the eutectoid direct current fast charging.

Fig. 5 shows the interactive process of the euro standard direct current fast charging. The BMS has two operating states, namely an awake state and a sleep state. When the whole vehicle is in the ON gear, the BMS is in an awake state, and when the whole vehicle is in the OFF gear, the BMS is in a sleep state. The flow of the European standard direct current quick charge is described below by taking the OFF gear of the whole vehicle as an example.

As shown in fig. 5, when the entire vehicle is in the OFF range, the EVCC is in a standby state. The inserting and robbing means that the charging gun is inserted into the European standard charging pile, so that the charging gun is connected with a physical circuit of the charging pile. In some embodiments, the gun may interact with the stake after the robbing action. In other embodiments, the card swipe is also required to start the charging stake after the insertion.

After the physical circuit connection is completed, the charging pile sends a PWM signal to the vehicle end. The EVCC receives the PWM signal and detects the PWM signal. Illustratively, the EVCC determines a charging mode between the charging post and the vehicle end according to a duty cycle of the PWM signal output by the charging post. The charging modes include a direct current fast charging mode and an alternating current slow charging mode. The PWM signal includes periodic pulses, and the duty cycle of the PWM signal refers to the ratio of the duration of the high level to the pulse period in each pulse period.

In some embodiments, when the EVCC detects that the duty cycle of the PWM signal is about 9% to 97%, it determines that the charging pile and the vehicle end are in an ac charging mode, that is, slow charging is performed. When the EVCC detects that the duty ratio of the PWM signal is about 3-7%, the direct current quick charging mode is judged between the charging pile and the vehicle end.

In this embodiment, after the EVCC confirms that the direct current (dc) fast charging mode, the EVCC outputs a wake-up signal to wake up the BMS. In a specific embodiment, the EVCC outputs a secondary source a+ signal to wake up the BMS. The a+ signal may be provided to the BMS via a hard wire such that the BMS switches from a sleep state to an awake state. It should be understood that if the whole vehicle is in the ON range, the BMS itself is in an awake state, and the BMS does not need to be woken up any more.

In addition, after the plugging action is completed, the EVCC can also detect the voltage signal of the PP interface, converts the detected voltage signal into a CC2 signal and sends the CC2 signal to the BMS, and the BMS judges whether the connection between the charging gun and the charging pile is normal or not according to the CC2 signal. And when the judgment result is that the plug-in connection is normal, permitting the charging process.

When the BMS is switched to the awake state, the BMS performs a self-checking action. The self-checking action includes insulation detection, down high voltage fault detection, etc. The insulation detection may include a vehicle end insulation detection, or an insulation detection of the entire charge stake and the vehicle end. Insulation detection is performed before the charging point to avoid the risk of leakage in charging. After the self-test is completed, the insulation test is turned off, that is, the high voltage applied to the charging circuit during the insulation test is removed.

In some embodiments, when the whole vehicle is in the OFF gear, the VCU is in the sleep state, so after the BMS is awakened, the VCU is also awakened through the CAN bus, so that the VCU is switched from the sleep state to the awakened state, and enters the working mode. If the whole vehicle is in the ON gear, the VCU itself is in the wake state, which is that the BMS may not perform the wake operation ON the VCU.

With continued reference to fig. 5, after the physical connection of the circuit is completed, the auxiliary source supplies power to the EVCC and the BMS, and the BMS completes self-checking, the charging process starts to enter, the EVCC performs PLC communication with the charging pile, and the direct current quick charging process specified by the national standard quick charging protocol GB 27930 is executed between the EVCC and the BMS. Specifically, the EVCC receives the PLC communication signal sent by the charging pile, converts the PLC communication signal into a CAN signal, and performs signal interaction with the BMS according to the dc fast charging flow specified by the national standard GB 27930.

The whole direct-current quick charging process comprises a handshake phase, a parameter configuration phase, a charging phase and a charging ending phase. And in the handshake stage, the EVCC and the BMS send messages according to the specification of the national standard GB 27930 to perform signal interaction. For example, 1) the EVCC forwards the CRM 00 message to the charging pile to apply for handshake. 2) When the BMS receives the CRM 00 message, the BMS transmits identity code information BRM of the current battery pack to the EVCC, and the identity code information BRM is forwarded to the charging pile by the EVCC. 3) The EVCC forwards the identification message CRM AA replied after the charging pile receives the BRM to the BMS. The BMS receives the CRM AA message to indicate that the handshake phase is ended, and enters a parameter configuration phase.

The parameter configuration phase, the signal interaction between the EVCC and the BMS may include: 1) The BMS sends out a charging parameter message BCP/BRO to the EVCC and forwards the charging parameter message BCP/BRO to the charging pile from the EVCC. 2) After the EVCC forwards the charging pile to receive the charging parameter message, the transmitted time synchronization message CTS and maximum output capacity message CML are sent to the BMS, and meanwhile, the charging pile carries out parameter configuration according to the charging parameter transmitted by the BMS.

In the standard European charging protocol, in the parameter configuration stage, a standard European charging pile performs pre-charging, and a pre-charging voltage is established at a quick charging interface (comprising a quick charging positive electrode interface and a quick charging negative electrode interface). After the precharge voltage is established, the EVCC forwards a maximum output capacity message CML sent by the charging pile to the BMS.

The embodiment of the disclosure provides that in a parameter configuration stage, the BMS performs first adhesion detection on a fast charging relay (comprising a fast charging positive relay and a fast charging negative relay). For example, the first instruction indicating the start of the parameter configuration phase may be a charging pile identification message CRM AA sent by the charging pile forwarded by the EVCC to the BMS. The charging pile identification message CRM AA indicates both the end of the handshake phase and the start of the parameter configuration phase. The second instruction indicating that the voltage of the first terminal of the relay reaches the precharge voltage may be a maximum output capability message CML transmitted to the BMS by the charging stake forwarded by the EVCC.

After the charging pile sends the CRM AA message, the charging pile starts to perform the pre-charging operation. As shown in fig. 5, after receiving the charging pile identification message CRM AA sent by the charging pile forwarded by the EVCC, the BMS starts to perform first adhesion detection on the fast charging relay. When the pre-charging voltage of the charging pile is established, the EVCC forwards a maximum output capacity message CML of the charging pile, and meanwhile, the BMS stops the first adhesion detection of the quick charging relay.

In some embodiments, step S110, during the step of increasing the voltage of the first terminal of the relay to the precharge voltage, sampling the first voltage of the first terminal and the second voltage of the second terminal of the relay a plurality of times, includes:

sampling the first voltage and the second voltage throughout a charging operation; or,

in response to a first instruction, beginning to sample the first voltage and the second voltage; in response to the second instruction, sampling of the first voltage and the second voltage is stopped.

In some embodiments, after the sampling circuit is powered, the sampling circuit samples the first end and the second end of the relay periodically all the time and sends the samples to the BMS, but the BMS does not process the received first voltage and second voltage, and only after receiving the first instruction, the steps S120 and S130 are started to determine whether the relay is stuck. After receiving the second instruction, the execution of steps S120 and S130 is stopped, that is, the judgment of whether the relay is stuck is stopped. By the arrangement, the adhesion detection circuit responds to the first instruction and the second instruction faster, and the circuit is simple to realize.

In other embodiments, the BMS may control the sampling voltage to perform step S110 after receiving the first command, start sampling the first voltage and the second voltage, and perform steps S120 and S130 by itself. After receiving the second command, the BMS controls the sampling circuit to stop performing the steps S110, that is, to stop sampling the first voltage and the second voltage, and the BMS itself also stops performing the steps S120 and S130. The arrangement can save the power consumption of the whole vehicle.

With continued reference to fig. 5, if the detection result is that the relay is stuck, the charging operation is ended. And if the detection result is that the relay is not adhered, allowing the charging operation to enter a charging stage.

In some embodiments, as shown in fig. 5, when receiving the maximum output capacity message CML of the charging pile forwarded by the EVCC, the BMS determines whether charging is possible based on the first adhesion detection results of the CML and the fast charging relay. If the fast charging relay is not adhered and the charging pile can charge the battery pack based on the message CML, the BMS continues to carry out subsequent message interaction with the EVCC and then enters a charging stage.

In one embodiment, when the BMS determines that charging is enabled, a fast charge request is sent to the VCU. After receiving the quick charge request, the VCU sends a relay closing instruction and a quick charge enable signal to the BMS. The relay closing instruction at least comprises fast charging positive relay closing and fast charging negative relay closing. After the BMS executes the relay closing instruction, the BMS interacts with the EVCC to carry out the charging stage after the messages BRO and CRO.

In the charging stage, the charging pile provides a direct-current power supply for the battery pack through the quick charging interface to charge, and forwards the interaction related message through the EVCC in the charging process.

After the charging is completed, the charging end stage is entered. In the related art, when the whole vehicle is in an OFF gear for charging, the vehicle can be directly powered down after the charging is finished, a high-voltage loop is disconnected (namely a main relay is disconnected), no voltage exists at a first end sampling point and a second end sampling point of a quick charging relay, so that the real adhesion state cannot be diagnosed through adhesion detection of the quick charging relay, and if adhesion exists, the high-voltage safety risk exists at a quick charging port after the follow-up power-up. In particular, some vehicle adhesion diagnostic schemes only perform relay adhesion detection after the end of charging, and direct current quick charge is directly entered without detection before charging.

Based on this, the adhesion detection method for the relay according to the embodiment of the present disclosure further includes: in the charging end period, the second adhesion detection is performed on the relay, as shown in fig. 6, and the step of performing the second adhesion detection on the relay includes:

s210: in the charging end period, the second end of the relay and the battery pack are kept in a conducting state, and the relay is disconnected;

S220: sampling a third voltage at a first end and a fourth voltage at a second end of the relay;

s230: determining a second actual differential pressure of the relay based on the third voltage and the fourth voltage;

s240: and comparing the second actual pressure difference with a second threshold pressure difference, and judging whether the relay is in an off state according to the comparison result.

In this embodiment, in the charging end period, the fast charging relay is turned off, and the second adhesion diagnosis is performed on the fast charging relay in the case where the main relay is not yet turned off. Referring back to fig. 4, at the end of charging, the high voltage of the charging pile 100 has been discharged, and the voltage of the fast charging interface dc+, DC-is 0V, i.e., the voltage of the first terminal a of the fast charging positive relay 410 and the first terminal C of the fast charging negative relay 440 is 0V. Since the main relays 420, 450 are not turned off, the fast charge relays 410, 440 and the battery pack 300 are turned on, and thus the voltages at the second terminal B of the fast charge positive relay 410 and the second terminal D of the fast charge negative relay 440 are equal to the voltages at the positive and negative poles of the battery pack, respectively, that is, the second terminal B of the fast charge positive relay 410 and the second terminal D of the fast charge negative relay 440 are both high voltages. If the fast charge positive relay 410 sticks, the voltage at the first terminal A of the fast charge positive relay 410 will be close to (including equal to) the voltage at the second terminal B thereof, less than the second threshold voltage. If the fast charge positive relay 410 is not stuck and is in a normal off state, the second actual voltage difference between the first end a and the second end B of the fast charge positive relay 410 is large, and the condition smaller than the second threshold voltage is not satisfied, so that it can be determined that the sticking is not occurred.

Similarly, if the fast charge-negative relay 440 sticks, the voltage at the second terminal D of the fast charge-negative relay 440 approaches the voltage at the first terminal C thereof and is less than the second threshold voltage. If the fast charge-negative relay 440 is not stuck, the second terminal D of the fast charge-negative relay 440 has no high voltage, and the second actual voltage difference between the first terminal C and the second terminal D of the fast charge-negative relay 440 does not satisfy the condition of less than the second threshold voltage, so that it can be determined that the sticking is not occurred.

In some embodiments, the first threshold voltage and the second threshold voltage may or may not be equal. In one embodiment, the first threshold voltage and the second threshold voltage are equal, and then one comparison circuit can be used to perform two sticky diagnoses, thereby simplifying the circuit.

In one embodiment, the second adhesion detection may sample the first and second ends of the relay only once, and the step of comparing the second actual differential pressure to the second threshold differential pressure may be performed once, thereby determining whether the relay is adhered by one sampling and judgment without having to sample multiple times as in the first adhesion detection. It should be appreciated that in other embodiments, a limited number of samplings and judgments may be made during the second stick test to improve the accuracy of the test. For example, two or three samples and determinations are made.

In some embodiments, at the end of charge phase, the relay is opened based on a third instruction to open the relay, followed by a second stick detection of the relay. For example, after the BMS receives the third command and turns off the relay, the BMS obtains a second actual voltage difference based on the received third voltage and fourth voltage, and compares the second actual voltage difference with the threshold voltage to determine whether the relay is stuck.

Referring again to fig. 5, after the end of charging, the BMS transmits a fast charge end signal to the VCU, and after receiving the fast charge end signal transmitted by the BMS, the VCU transmits an end fast charge enable signal (which may also be referred to as a fast charge disable signal) to the BMS. The BMS turns off the fast charging relay when receiving the fast charging disabling signal of the VCU, and executes the second fast charging relay adhesion detection to confirm whether the fast charging relay has adhesion failure.

After the second relay adhesion detection, the VCU sends a high-voltage/low-voltage command (also called a power-ON/power-OFF command) to the BMS according to whether the whole vehicle is in the ON gear or the OFF gear before charging, and the BMS controls the main relay to execute. In this embodiment, as shown in fig. 5, the VCU sends a low-voltage command to the BMS, and the BMS controls the main relay to be turned off, thereby completing the fast charging operation.

Referring back to fig. 4, the battery system further includes a current sensor 610 and fuses 620, 630, the current sensor 610 being connected in series between the positive electrode of the battery pack 300 and the main positive relay 420 for detecting current during charging and power supply of the battery pack 300. The fuses 620, 630 are used to prevent damage to electrical components when the current in the battery circuit is too high or exceeds the load current by blowing itself to shut off the battery circuit. The battery system also comprises an accessory positive and negative interface, a precursor positive and negative interface and a rear-drive positive and negative interface, wherein the accessory is used for supplying power to the accessory of the vehicle and comprises an air conditioning system and the like. The front drive positive and negative interfaces and the rear drive positive and negative interfaces are used for supplying power to a driving motor of the vehicle so as to enable the vehicle to obtain power.

The embodiment of the disclosure provides an implementation mode of European standard direct current fast charging and a decision mechanism for performing fast charging relay adhesion diagnosis based on the mode BMS, wherein the decision mechanism comprises adhesion diagnosis. By utilizing the strategy, whether the fast charging relay is adhered or not can be accurately diagnosed before and after the European standard direct current fast charging, faults are timely reported, error diagnosis is effectively avoided, and the high-voltage safety performance of the whole vehicle is improved extremely.

The embodiment of the disclosure also provides a blocking detection circuit, as shown in fig. 7, which includes:

The relay comprises a first end and a second end, wherein the first end is used for being connected with a charging interface, and the second end is used for being connected with the battery pack 300;

sampling circuit 700, connecting the first and second terminals of the relay, is configured to: sampling the first voltage of the first terminal and the second voltage of the second terminal of the relay a plurality of times during the voltage of the first terminal of the relay increases to the precharge voltage;

a Battery Management System (BMS) 220, coupled to the sampling circuit 700, is configured to: determining a plurality of first actual pressure differences corresponding to the relay at a plurality of sampling moments according to the first voltage and the second voltage which are sampled for a plurality of times; comparing the plurality of first actual pressure differences with a first threshold pressure difference to obtain a plurality of comparison results; judging whether the relay is adhered or not according to the comparison results.

In some embodiments, the battery management system 220 is configured to: the absolute value of the difference between the first voltage and the second voltage for each sample is obtained as a first actual differential pressure of the relay.

In one embodiment, the BMS220 may include an analog-to-digital converter for converting the first voltage and the second voltage into a first digital signal and a second digital signal, respectively, and a subtractor connected to the analog-to-digital converter, for differencing the first digital signal and the second digital signal, and outputting an absolute value of the difference as the first actual differential pressure signal.

In some embodiments, the battery management system 220 is configured to:

In one embodiment, the battery management system 220 further includes: the input end of the comparator is connected with the sampling circuit 700 and is used for receiving a first threshold voltage difference signal and a first actual voltage difference signal, comparing the two signals and storing a comparison result in the register. Illustratively, the comparator output signal 1 indicates that the first actual differential pressure signal is greater than or equal to the first threshold differential pressure signal, and the output signal 0 indicates that the first actual differential pressure signal is less than the first threshold voltage. The register receives the signal 1 or 0 output by the comparator, wherein if the plurality of first actual differential pressures are smaller than the first threshold differential pressure, the signal 0 is stored in the register after stopping detection. And if the at least one first actual pressure difference is greater than or equal to the first threshold pressure difference, storing a signal 1 in the register after stopping detection. Therefore, whether the relay is stuck or not can be judged based on the signals in the register.

In some embodiments, the charging operation process of the battery pack includes a handshake phase, a parameter configuration phase, a charging phase, and a charging end phase; the battery management system is configured to:

determining a first actual pressure difference of the relay at the sampling time according to the first voltage and the second voltage sampled each time during the period from the first time when the first instruction is received to the second time when the second instruction is received; comparing the first actual pressure difference with a first threshold pressure difference to obtain a comparison result;

In a specific embodiment, the signal control end of the comparator is configured to receive the first instruction and the second instruction.

In some embodiments, the first instruction is a charging pile identification message; and/or the second instruction is a maximum output capacity message of the charging pile.

In some embodiments, the sampling circuit is configured to: sampling the first voltage and the second voltage all the time during a charging operation; or,

starting to sample the first voltage and the second voltage based on the first instruction; based on the second instruction, sampling of the first voltage and the second voltage is stopped.

As shown in fig. 7, the relay is either a fast charge positive relay 410 or a fast charge negative relay 440. The sampling terminals of the sampling circuit 700 are respectively connected to the first terminal a and the second terminal B of the fast charge positive relay 410, the first terminal C and the second terminal D of the fast charge negative relay 440, and the terminal E of the main negative relay 450 near the battery pack. The end E of the main negative relay 450 near the battery pack is a high voltage detection reference point. The sampling circuit is used for acquiring voltages of a first terminal a and a second terminal B of the fast charge positive relay 410, and a first terminal C and a second terminal D of the fast charge negative relay 440 with respect to a high voltage detection reference point. The sampling circuit 700 is also coupled to the battery management system 220 to transmit the sampled first voltage, second voltage, third voltage, and fourth voltage to the battery management system 220.

In some embodiments, the sampling circuit 700 is powered to periodically sample the voltage at the first and second terminals of the relay at all times. In other embodiments, the sampling circuit 700 starts sampling or stops sampling the voltage at the first and second terminals of the relay in response to the control signals sent by the battery management system 220 based on the first and second instructions.

In some embodiments, the battery management system 220 is further configured to:

In the charging end period, maintaining the conduction state of the second end of the relay and the battery pack, and disconnecting the relay;

The present disclosure also provides a vehicle comprising the adhesion detection circuit of any one of the embodiments above.

Claims

1. The relay adhesion detection method is characterized in that the relay comprises a first end and a second end, wherein the first end is used for being connected with a charging interface, and the second end is used for being connected with a battery pack; the method comprises the following steps:

2. The relay adhesion detection method of claim 1, wherein determining a plurality of first actual differential pressures of the relay at a plurality of sampling times based on the first voltage and the second voltage sampled a plurality of times comprises:

3. The relay adhesion detection method according to claim 1, wherein the determining whether the relay is in an off state based on the plurality of comparison results includes:

4. The relay adhesion detection method of claim 1, wherein the charging operation process of the battery pack includes a handshake phase, a parameter configuration phase, a charging phase, and a charging end phase;

5. The relay adhesion detection method of claim 4, wherein sampling the first voltage of the first terminal and the second voltage of the second terminal of the relay multiple times during the voltage rise of the first terminal of the relay to the precharge voltage comprises:

6. The relay adhesion detection method of claim 4, wherein the first instruction is a charging pile identification message; and/or the number of the groups of groups,

7. The relay adhesion detection method of claim 4, further comprising:

8. A relay adhesion detection circuit, comprising:

9. The relay adhesion detection circuit of claim 8, wherein the battery management system is configured to:

10. The relay adhesion detection circuit of claim 8, wherein the battery pack charging operation process comprises a handshaking phase, a parameter configuration phase, a charging phase, and a charging end phase; the battery management system is configured to:

11. The relay adhesion detection circuit of claim 10, wherein the battery management system is further configured to:

12. The relay adhesion detection circuit of claim 8, wherein the relay is a fast charge positive relay or a fast charge negative relay.

13. A vehicle comprising the relay adhesion detection circuit according to any one of claims 8 to 12.