Adhesion detection circuit and method of main negative relay and electric vehicle

Abstract

The embodiment of the invention discloses an adhesion detection circuit and method of a main negative relay and an electric vehicle, and belongs to the technical field of new energy. The circuit comprises a main negative relay, a battery controller and a sampling divider resistor, the main negative relay comprises a front end voltage measuring point and a rear end voltage measuring point, the battery controller comprises a power supply pin and a voltage measuring pin, and the voltage measuring pin is connected with the front end voltage measuring point and the rear end voltage measuring point; the battery controller is used for providing voltage for the adhesion detection circuit through the power supply pin; the sampling divider resistor is used for dividing the voltage output by the power supply pin; the battery controller is further used for obtaining a voltage measurement value through the voltage measurement pin and determining the adhesion state of the main negative relay based on the voltage measurement value. By adopting the scheme provided by the embodiment of the invention, the adhesion state of the main negative relay can be effectively detected, and the cost of the detection circuit is reduced.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of new energy technology, and in particular to a main negative relay adhesion detection circuit, method and electric vehicle. Background Art

[0002] The main negative relay is responsible for controlling the connection between the negative pole of the battery pack and the external load or charger. The main negative relay is usually closed after the pre-charge relay to ensure the voltage balance between the battery system and the external power supply or load, avoid current shock caused by voltage difference, and protect the circuit and battery.

[0003] In the related art, the sticking state of the main negative relay is detected by cross detection, by comparing the PACK+ voltage (positive voltage of the battery pack) with the PACK- voltage (total voltage of the battery pack, that is, the voltage at the front end of the relay), the PACK+ voltage with the LINK- voltage (the voltage at the rear end of the relay), and comparing the voltage difference between the two. If the voltage difference is small, it is determined that the main negative relay is stuck. However, this cross detection circuit requires a separate isolated power supply, which is costly. Summary of the invention

[0004] The present application example provides a main negative relay adhesion detection circuit, method and electric vehicle, and the technical solution is as follows.

[0005] On the one hand, an embodiment of the present application provides a main negative relay adhesion detection circuit, the circuit includes a main negative relay, a battery controller and a sampling voltage-dividing resistor, the main negative relay includes a front-end voltage measurement point and a rear-end voltage measurement point, the battery controller includes a power supply pin and a voltage measurement pin, and the voltage measurement pin is connected to the front-end voltage measurement point and the rear-end voltage measurement point;

[0006] The battery controller is used to provide voltage to the adhesion detection circuit through the power supply pin;

[0007] The sampling voltage-dividing resistor is used to perform voltage-dividing processing on the voltage output by the power supply pin;

[0008] The battery controller is also used to obtain a voltage measurement value through the voltage measurement pin, and determine the adhesion state of the main negative relay based on the voltage measurement value.

[0009] Optionally, the circuit includes an isolation optocoupler and a current-limiting resistor, the isolation optocoupler includes a light-emitting diode and a phototransistor, and the battery controller also includes a level output pin;

[0010] The first resistor pin of the current limiting resistor is connected to the level output pin, the second resistor pin of the current limiting resistor is connected to the anode of the light emitting diode, and the cathode of the light emitting diode is grounded; the collector of the phototransistor is connected to the power supply pin and the voltage measurement pin, and the emitter of the phototransistor is connected to the rear-end voltage measurement point;

[0011] The battery controller is used to output a high level through the level output pin to put the isolation optocoupler in a conducting state.

[0012] Optionally, the sampling voltage-dividing resistor includes a first resistor, a second resistor and a third resistor;

[0013] The first resistor pin of the first resistor is connected to the voltage measurement pin, and the second resistor pin of the first resistor is connected to the collector of the phototransistor;

[0014] The first resistor pin of the second resistor is connected to the power supply pin, and the second resistor pin of the second resistor is connected to the collector of the phototransistor;

[0015] The first resistor pin of the third resistor is connected to the emitter of the phototransistor, and the second resistor pin of the third resistor is connected to the rear-end voltage measurement point.

[0016] Optionally, the battery controller is used to:

[0017] When the isolation optocoupler is in an on state, obtaining the voltage measurement value through the voltage measurement pin;

[0018] The sticking state of the main negative relay is determined based on the voltage measurement value and the resistance voltage division value formed by the sampling voltage division resistor.

[0019] Optionally, the battery controller is used to:

[0020] When the voltage measurement value is equal to the first resistance voltage division value, determining that the main negative relay is in a sticking state;

[0021] In a case where the voltage measurement value is equal to the second resistance divided voltage value, it is determined that the main negative relay is in a non-sticking state.

[0022] Optional,

[0023] When the main negative relay is in a sticking state, the front-end voltage measurement point and the rear-end voltage measurement point are at the same potential, and the first resistor voltage division value is the voltage value after voltage division by the first resistor, the second resistor and the third resistor.

[0024] When the main negative relay is in a non-adhesive state, the front-end voltage measurement point and the rear-end voltage measurement point are not in common, and the second resistor voltage division value is a voltage value after voltage division by the first resistor and the second resistor.

[0025] Optionally, the circuit further includes a filter resistor and a filter capacitor; the first resistor pin of the filter resistor is connected to the voltage measurement pin, and the second resistor pin of the filter resistor is connected to the first resistor pin of the first resistor; the first capacitor pin of the filter capacitor is connected to the voltage measurement pin, and the second capacitor pin of the filter capacitor is grounded;

[0026] The filter resistor and the filter capacitor are used to perform filtering processing on the adhesion detection circuit.

[0027] Optionally, the circuit further comprises a transformer, the primary coil of the transformer is connected to the output pin of the battery controller, and the secondary coil of the transformer is connected to the communication link of the micro control unit;

[0028] The battery controller is used to transmit the adhesion state signal corresponding to the main negative relay to the micro control unit through the transformer.

[0029] On the other hand, an embodiment of the present application provides a main negative relay adhesion detection method, the method is used for a main negative relay adhesion detection circuit, the circuit includes a main negative relay, a battery controller and a sampling voltage-dividing resistor, the main negative relay includes a front-end voltage measurement point and a rear-end voltage measurement point, the battery controller includes a power supply pin and a voltage measurement pin, the voltage measurement pin is connected to the front-end voltage measurement point and the rear-end voltage measurement point;

[0030] The method comprises:

[0031] Providing voltage to the adhesion detection circuit through the power supply pin of the battery controller;

[0032] Reducing the voltage output by the power supply pin through the sampling voltage-dividing resistor;

[0033] A voltage measurement value is obtained through the voltage measurement pin of the battery controller, and the adhesion state of the main negative relay is determined based on the voltage measurement value.

[0034] On the other hand, an embodiment of the present application provides an electric vehicle, which includes a sticking detection circuit of the main negative relay as described in the above aspect.

[0035] In an embodiment of the present application, a battery controller and a sampling voltage-divider resistor are used to design a adhesion detection circuit for a main negative relay. Voltage is provided to the adhesion detection circuit through a power supply pin of the battery controller, and after voltage division processing by a sampling voltage-divider resistor, a voltage measurement value is obtained through a voltage measurement pin, thereby determining the adhesion state of the main negative relay based on the voltage measurement value. This enables effective detection of the adhesion state of the main negative relay while reducing the cost of the detection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 A schematic diagram of a main negative relay adhesion detection circuit provided by an exemplary embodiment of the present application is shown;

[0038] Figure 2 A circuit structure diagram of a main negative relay adhesion detection circuit provided by an exemplary embodiment of the present application is shown;

[0039] Figure 3 An equivalent circuit diagram between a power supply pin and a voltage measurement pin when a main negative relay provided by an exemplary embodiment of the present application is in a sticking state is shown;

[0040] Figure 4 An equivalent circuit diagram between a power supply pin and a voltage measurement pin when a main negative relay provided by an exemplary embodiment of the present application is in a non-adhesive state is shown;

[0041] Figure 5 A flow chart of a main negative relay adhesion detection method provided by an exemplary embodiment of the present application is shown. DETAILED DESCRIPTION

[0042] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0043] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0044] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0045] It should be understood that, although the terms first, second, etc. may be used in the present application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first parameter may also be referred to as the second parameter, and similarly, the second parameter may also be referred to as the first parameter. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0046] First, the nouns involved in the embodiments of the present application are briefly introduced:

[0047] Main negative relay: responsible for controlling the connection between the negative pole of the battery pack and the external load or charger. The main negative relay is usually closed after the pre-charge relay to ensure the voltage balance between the battery system and the external power supply or load, avoid current shock caused by voltage difference, and protect the circuit and battery.

[0048] During the charging process, the closing order of the relays is usually: first close the pre-charge relay, then the main negative relay, and finally the main positive relay. The order of disconnection is the opposite, first disconnect the main positive relay, then disconnect the main negative relay, and finally disconnect the pre-charge relay.

[0049] Battery controller: It is the core component of the battery management system (BMS). It is responsible for monitoring and managing the battery's charge and discharge process to ensure that the battery operates safely and efficiently. The battery controller IC (Integrated Circuit) can monitor the battery voltage in real time to ensure that the battery operates within a safe voltage range.

[0050] Isolation optocoupler: an electronic component that uses optical signals to electrically isolate input and output. It usually consists of a light-emitting device (such as an infrared light-emitting diode LED) and a photosensitive device (such as a phototransistor, photodiode, Darlington tube, optical integrated circuit, etc.). The two parts are encapsulated in the same housing, and the electrical signal is transmitted in the middle through the electrical-optical-electrical conversion, thereby achieving electrical isolation between input and output.

[0051] Daisy Chain Communication: is a method of establishing a communication link between electronic devices, where each device is connected to the next device in turn, forming a single communication path. In daisy chain communication, data is transmitted from one device to the next until it reaches the end of the link. After receiving the data, each device processes the data according to its own needs and then passes the data to the next device in the link. This communication method can reduce the number of communication cables required, thereby reducing the cost and complexity of the system.

[0052] In the related art, the adhesion state of the main negative relay is detected by cross detection. By comparing the positive voltage (PACK+) of the battery pack and the voltage (PACK-) of the front end of the relay, and comparing the positive voltage (PACK+) of the battery pack and LINK- (the voltage of the rear end of the relay), it is determined whether the main negative relay is in the adhesion state based on the voltage comparison result. When the voltage difference is small, it is determined that the main negative relay is in the adhesion state; when the voltage difference is large, it is determined that the main negative relay is in the non-adhesion state.

[0053] However, the above cross-detection method requires the use of an isolated power supply in the circuit, resulting in high circuit cost. In addition, the cross-sampling adhesion detection circuit needs to be integrated with the microcontroller unit (MCU), that is, the main board and the high-voltage board cannot be separated, which is not suitable for distributed battery management systems.

[0054] Based on this, an embodiment of the present application proposes a adhesion detection circuit for a main negative relay, which samples the voltage after being divided by a voltage divider resistor through a battery controller, and thereby determines the adhesion state of the main negative relay based on the voltage measurement value. This can achieve effective detection of the adhesion state of the main negative relay while reducing the cost of the adhesion detection circuit.

[0055] The adhesion detection circuit of the main negative relay proposed in this application will be described below through specific embodiments.

[0056] Please refer to Figure 1 , which shows a framework schematic diagram of a main negative relay adhesion detection circuit provided by an exemplary embodiment of the present application.

[0057] like Figure 1As shown, the adhesion detection circuit includes a main negative relay 110, a battery controller 120 and a sampling voltage-dividing resistor 130. The main negative relay 110 includes a front-end voltage measurement point (PACK-) and a rear-end voltage measurement point (LINK-), and the battery controller 120 includes a power supply pin (VCOM) and a voltage measurement pin (GPIOA), and the voltage measurement pin is connected to the front-end voltage measurement point and the rear-end voltage measurement point.

[0058] Optionally, the main negative relay is responsible for controlling the connection between the negative terminal of the battery pack and the external load or charger. The main negative relay is usually closed after the pre-charge relay to ensure the voltage balance between the battery system and the external power supply or load, avoid current shock caused by voltage difference, and protect the circuit and battery.

[0059] Optionally, the working state of the main negative relay can be detected by detecting the voltages at the front and rear ends of the main negative relay, wherein the voltage measurement points of the main negative relay usually include LINK-voltage, LINK+voltage, PACK-voltage, and PACK+voltage.

[0060] Optionally, LINK-voltage refers to the negative voltage at the rear end of the relay, that is, the negative voltage of the battery pack after it is connected to an external load or charger through the main negative relay. Monitoring of LINK-voltage helps determine whether the relay is normally turned on and whether the circuit between the battery pack and the external load is connected.

[0061] Optionally, the LINK+ voltage refers to the positive voltage at the rear end of the relay, that is, the positive voltage of the battery pack after it is connected to the external load or charger through the main negative relay. Monitoring the LINK+ voltage helps determine whether the relay is normally turned on and whether the circuit between the battery pack and the external load is connected.

[0062] Optionally, PACK-voltage refers to the front-end voltage of the main negative relay, that is, the negative connection point of the battery pack. This voltage reflects the overall voltage level of the battery pack and is the first voltage parameter to be considered when the battery system is connected to an external device (such as a charger).

[0063] Optionally, PACK+ voltage refers to the positive voltage of the battery pack. PACK+ is the summary point of all positive connections of the battery pack and represents the positive connection voltage provided to the outside by the entire battery pack. In battery series or parallel configuration, PACK+ is the positive voltage reference point connected to the battery management system and high voltage electrical system. PACK+ voltage is the voltage source that provides energy to the battery system and is critical for monitoring the battery status and managing the charge and discharge process of the system.

[0064] In the embodiment of the present application, the adhesion detection circuit of the main negative relay needs to be connected to the front-end voltage measurement point (PACK-) and the rear-end voltage measurement point (LINK-) of the main negative relay.

[0065] The battery controller 120 is used to provide voltage to the adhesion detection circuit through the power supply pin.

[0066] Optionally, the battery controller can monitor the voltage of the battery in real time to ensure that the battery operates within a safe voltage range. In the embodiment of the present application, the model of the battery controller can be MC33772, a six-channel lithium-ion battery controller.

[0067] Optionally, the battery controller includes a power supply pin (VCOM), which is used to output a voltage signal to the adhesion detection circuit.

[0068] Optionally, the power supply pin may be connected to a front-end voltage measurement point and a rear-end voltage measurement point of the main negative relay via a sampling voltage-dividing resistor.

[0069] The sampling voltage-dividing resistor 130 is used to divide the voltage outputted by the power supply pin.

[0070] Optionally, when using a battery controller to detect the voltage of the main negative relay, a sampling voltage divider resistor can be set between the battery controller and the main negative relay. The resistor is used to divide the voltage output by the power supply pin so that the battery controller can measure the divided voltage value through the voltage measurement pin.

[0071] The battery controller 120 is further used to obtain a voltage measurement value through a voltage measurement pin, and determine the adhesion state of the main negative relay 110 based on the voltage measurement value.

[0072] Optionally, the battery controller includes multiple input / output (GPIO) pins, one of which can be configured as an ADC (Analog-to-Digital Converter) input and as a voltage measurement pin, so that the voltage in the adhesion detection circuit is measured through the voltage measurement pin to obtain a voltage measurement value, and then the adhesion state of the main negative relay is determined based on the voltage measurement value.

[0073] Optionally, when the main negative relay is in a non-sticky state, it means that the main negative relay is in a normal working state; when the main negative relay is in a sticky state, it means that the contacts of the main negative relay are stuck and cannot be switched normally. This situation may cause the main negative relay to remain in the "on" or "off" state, thereby causing safety hazards and equipment failures.

[0074] To sum up, in the embodiment of the present application, a battery controller and a sampling voltage-divider resistor are used to design a adhesion detection circuit of the main negative relay. The voltage is provided to the adhesion detection circuit through the power supply pin of the battery controller, and after the voltage division processing by the sampling voltage-divider resistor, the voltage measurement value is obtained through the voltage measurement pin, so as to determine the adhesion state of the main negative relay according to the voltage measurement value. This can achieve the goal of effectively detecting the adhesion state of the main negative relay while reducing the cost of the detection circuit.

[0075] In some embodiments, in order to effectively control the relay adhesion detection process during the operation of the electric vehicle, an isolation optocoupler may be designed in the adhesion detection circuit, thereby achieving switch control of the adhesion detection by controlling the on and off state of the isolation optocoupler.

[0076] Please refer to Figure 2 , which shows a circuit structure diagram of a main negative relay adhesion detection circuit provided by an exemplary embodiment of the present application.

[0077] Indicatively, Figure 2 As shown, the battery controller 210 includes a power supply pin (VCOM), a voltage measurement pin (GPIOA) and a level output pin (GPIOB), and the adhesion detection circuit includes an isolation optocoupler 220, and the isolation optocoupler 220 includes a light-emitting diode 222 and a phototransistor 221. By connecting the level output pin to the light-emitting diode 222 in the isolation optocoupler 220, the on-off state of the isolation optocoupler can be controlled by the output level, thereby realizing the switch control of the adhesion detection.

[0078] Optionally, the adhesion detection circuit may further include a current limiting resistor 240, which is located between the level output pin (GPIOB) and the light emitting diode 222 and is used to limit the current flowing through the light emitting diode 222 to prevent the light emitting diode 222 from being damaged by excessive current.

[0079] Indicatively, Figure 2 As shown, the first resistance pin of the current limiting resistor 240 is connected to the level output pin, the second resistance pin of the current limiting resistor 240 is connected to the anode of the light emitting diode 222, and the cathode of the light emitting diode 222 is grounded.

[0080] Optionally, based on the working principle of the isolation optocoupler, the collector of the phototransistor 221 in the isolation optocoupler 220 can also be connected to the power supply pin and the voltage measurement pin, and the emitter of the phototransistor 221 can be connected to the rear-end voltage measurement point.

[0081] The battery controller 210 is used to output a high level through the level output pin to make the isolation optical coupler in a conducting state.

[0082] Optionally, when the level output pin (GPIOB) outputs a high level, current flows into the anode of the light-emitting diode 222, and the light-emitting diode 222 is turned on and emits light, thereby converting the electrical signal into an optical signal. When the phototransistor 221 receives the optical signal, it will generate current according to the internal photoelectric effect, thereby converting the optical signal into an electrical signal, thereby connecting the power supply pin of the battery controller 210 to the rear-end voltage measurement point (LINK-) of the main negative relay, thereby starting the adhesion detection of the main negative relay.

[0083] Optionally, when the level output pin (GPIOB) does not output a high level, the light-emitting diode 222 cannot convert the electrical signal into an optical signal, and the phototransistor 221 cannot be turned on, that is, the power supply pin of the battery controller 210 and the rear-end voltage measurement point (LINK-) of the main negative relay cannot be turned on, that is, the adhesion detection of the main negative relay is stopped.

[0084] In some embodiments, during the adhesion detection process, in order to accurately determine the adhesion state of the main negative relay according to the voltage measurement value, it is also necessary to design an appropriate sampling voltage-dividing resistor in the adhesion detection circuit. Optionally, the sampling voltage-dividing resistor may include a first resistor, a second resistor, and a third resistor, and the three resistors are respectively arranged between the power supply pin and the isolation optocoupler, between the voltage measurement pin and the isolation optocoupler, and between the isolation optocoupler and the rear end voltage measurement point of the main negative relay.

[0085] Indicatively, Figure 2 As shown, the sampling voltage-dividing resistor may include a first resistor (R2) 231, a second resistor 232, and a third resistor (R5) 233, wherein the second resistor 232 is composed of a resistor R3 and a resistor R4 connected in series.

[0086] Indicatively, Figure 2 As shown, the first resistor pin of the first resistor 231 is connected to the voltage measurement pin of the battery controller 210, the first resistor pin of the first resistor 231 is connected to the front-end voltage measurement point of the main negative relay, and the second resistor pin of the first resistor 231 is connected to the collector of the phototransistor 221 in the isolation optocoupler 220. The first resistor pin of the second resistor 232 is connected to the power supply pin of the battery controller 210, and the second resistor pin of the second resistor 232 is connected to the collector of the phototransistor 221 in the isolation optocoupler 220. The first resistor pin of the third resistor 233 is connected to the emitter of the phototransistor 221 in the isolation optocoupler 220, and the second resistor pin of the third resistor 233 is connected to the rear-end voltage measurement point of the main negative relay.

[0087] Optionally, in order to improve the accuracy of the voltage measurement value, a filter circuit may be provided at the voltage measurement pin of the adhesion detection circuit to filter the voltage signal. Optionally, the filter circuit is composed of a filter resistor and a filter capacitor.

[0088] Indicatively, Figure 2 As shown, the adhesion detection circuit includes a filter resistor (R1) 251 and a filter capacitor (C1) 252. The first resistor pin of the filter resistor 251 is connected to the voltage measurement pin of the battery controller 210, the second resistor pin of the filter resistor 251 is connected to the first resistor pin of the first resistor 231, and the second resistor pin of the filter resistor 251 is connected to the front-end voltage measurement point of the main negative relay. The first capacitor pin of the filter capacitor 252 is connected to the voltage measurement pin of the battery controller 210, and the second capacitor pin of the filter capacitor 252 is grounded.

[0089] Optionally, the filter resistor 251 and the filter capacitor 252 are used to perform filtering processing on the adhesion detection circuit.

[0090] In one possible implementation, in the process of the battery controller obtaining the voltage measurement value through the voltage measurement pin, in order to reduce or eliminate the high-frequency noise and ripple in the voltage signal, after the current flows through the sampling voltage divider resistor, the adhesion detection circuit can be filtered through the filter resistor and the filter capacitor, thereby improving the accuracy of the voltage measurement value.

[0091] Based on the circuit structure diagram of the above-mentioned adhesion detection circuit, the adhesion detection process of the main negative relay will be specifically described below.

[0092] Optionally, the battery controller is used to obtain a voltage measurement value through the voltage measurement pin when the isolation optocoupler is in an on state.

[0093] In some embodiments, after the battery controller outputs a high level through the level output pin (GPIOB), the light emitting diode is turned on to convert the electrical signal into an optical signal, so that after receiving the optical signal, the phototransistor converts the optical signal into an electrical signal, that is, the isolation optocoupler is in the on state, so that the power supply pin of the battery controller is connected to the rear end voltage measurement point (LINK-) of the main negative relay, and the battery controller can obtain the voltage measurement value through the voltage measurement pin.

[0094] Optionally, the battery controller is used to determine the adhesion state of the main negative relay based on the voltage measurement value and the resistance voltage divider value formed by the sampling voltage divider resistor.

[0095] In some embodiments, after obtaining the voltage measurement value, the battery controller can determine the sticking state of the main negative relay by comparing the voltage measurement value and the resistance voltage divider value formed by the sampling voltage divider resistor.

[0096] Optionally, when the voltage measurement value is equal to the first resistance voltage divider value, it is determined that the main negative relay is in a sticking state; when the voltage measurement value is equal to the second resistance voltage divider value, it is determined that the main negative relay is in a non-sticking state.

[0097] Among them, when the main negative relay is in a sticking state, the front-end voltage measurement point and the rear-end voltage measurement point are at the same potential, that is, the front-end voltage measurement point and the rear-end voltage measurement point inside the main negative relay are in a conductive state. At this time, since the phototransistor is also in a conductive state, the first resistor (R2) and the third resistor (R5) are in a parallel state, and the first resistor voltage division value can be set to the voltage value after the voltage is divided by the first resistor, the second resistor and the third resistor.

[0098] Indicatively, Figure 3 As shown, Figure 3 FIG. 1 shows an equivalent circuit diagram between a power supply pin and a voltage measurement pin when a main negative relay provided by an exemplary embodiment of the present application is in a sticking state. Figure 3 It can be seen that when the main negative relay is in a sticking state, the first resistor R2 and the third resistor R5 are in a parallel state, and there are two current paths between the power supply pin (VCOM) and the voltage measurement pin (GPIOA). At this time, if the voltage measurement value at the voltage measurement pin (GPIOA) is equal to the first resistor voltage division value, it means that the first resistor R2 and the third resistor R5 are in a parallel state, that is, it can be determined that the main negative relay is in a sticking state.

[0099] Optional, based on Figure 3 As can be seen from the equivalent circuit diagram shown, the voltage formula of the first resistor voltage division value can be expressed as VCOM*(R2 / / R5) / (R3+R4+(R2 / / R5)).

[0100] Among them, when the main negative relay is in a non-adhesive state, the front-end voltage measurement point and the rear-end voltage measurement point do not share a common ground, that is, in the adhesion detection circuit, the front-end voltage measurement point and the rear-end voltage measurement point are in a disconnected state, and the second resistance voltage divider value can be set to the voltage value after the first resistor and the second resistor divider.

[0101] Indicatively, Figure 4 As shown, Figure 4 FIG. 1 shows an equivalent circuit diagram between a power supply pin and a voltage measurement pin when a main negative relay provided by an exemplary embodiment of the present application is in a non-adhesive state. Figure 4It can be seen that when the main negative relay is in a non-adhesive state, there is only one current path between the power supply pin (VCOM) and the voltage measurement pin (GPIOA). At this time, if the voltage measurement value at the voltage measurement pin (GPIOA) is equal to the second resistor voltage divider value, it means that the first resistor R2 and the third resistor R5 are not in a parallel state, and it can be determined that the main negative relay is in a non-adhesive state.

[0102] Optional, based on Figure 4 As can be seen from the equivalent circuit diagram shown, the voltage formula of the second resistor voltage division value can be expressed as VCOM*R2 / (R3+R4+R2).

[0103] It should be noted that in the process of setting the resistance voltage divider value in the embodiment of the present application, considering that the filter circuit (filter resistor and filter capacitor) has little effect on the voltage division, the filter resistor and filter capacitor are not introduced into the voltage formula.

[0104] Different from the related art, the cross-sampling adhesion detection circuit needs to be integrated with the micro control unit. In the embodiment of the present application, when the battery controller is used to detect the adhesion state of the main negative relay, the adhesion state signal corresponding to the main negative relay can be sent to the micro control unit based on daisy chain communication.

[0105] In some embodiments, the adhesion detection circuit may further include a transformer, wherein the primary coil of the transformer is connected to the output pin of the battery controller, and the secondary coil of the transformer is connected to the communication link of the micro control unit.

[0106] Optionally, the battery controller is used to transmit a sticking state signal corresponding to the main negative relay to the micro control unit through a transformer.

[0107] Optionally, the microcontroller unit is a low-voltage MCU board on which multiple daisy chain interfaces are provided, so that the two pins on the secondary coil of the transformer can be connected to any two daisy chain interfaces, thereby realizing the application of the main negative relay adhesion detection circuit proposed in the present application in a distributed battery management system.

[0108] Indicatively, Figure 2 As shown, the primary coil of the transformer 260 is connected to the output pin of the battery controller 210, and the two pins of the secondary coil of the transformer 260 are respectively connected to the signal input pin (RDTX+) and the signal output pin (RDTX-) of the micro control unit. Furthermore, after the battery controller 210 detects the adhesion state of the main negative relay, the adhesion state signal can be transmitted to the micro control unit through the transformer in a daisy chain communication manner, so that the micro control unit generates an alarm signal to remind the driver and passengers to detect the main negative relay.

[0109] In the above embodiment, by designing an isolation optocoupler in the adhesion detection circuit and controlling the on-off state of the isolation optocoupler, the switch control of the adhesion detection is realized. And according to the adhesion state of the main negative relay and the actual circuit design of the sampling voltage divider resistor, a corresponding resistance voltage divider value is set, so that by comparing the voltage measurement value with the resistance voltage divider value, the adhesion state of the main negative relay is accurately determined, and the effective detection of the adhesion state of the main negative relay is realized.

[0110] Furthermore, when the battery controller is used to detect the adhesion state of the main negative relay, a daisy chain communication method is adopted to transmit the adhesion state signal to the micro control unit through the transformer, so that the adhesion detection circuit can be separated from the micro control unit, simplifying the circuit design.

[0111] Please refer to Figure 5 , which shows a flow chart of a main negative relay adhesion detection method provided by an exemplary embodiment of the present application. The method is used for a main negative relay adhesion detection circuit, the circuit includes a main negative relay, a battery controller and a sampling voltage divider resistor, the main negative relay includes a front-end voltage measurement point and a rear-end voltage measurement point, the battery controller includes a power supply pin and a voltage measurement pin, and the voltage measurement pin is connected to the front-end voltage measurement point and the rear-end voltage measurement point.

[0112] Optionally, the main negative relay is responsible for controlling the connection between the negative terminal of the battery pack and the external load or charger. The main negative relay is usually closed after the pre-charge relay to ensure the voltage balance between the battery system and the external power supply or load, avoid current shock caused by voltage difference, and protect the circuit and battery.

[0113] Optionally, the working state of the main negative relay can be detected by detecting the voltages at the front and rear ends of the main negative relay, wherein the voltage measurement points of the main negative relay usually include LINK-voltage, LINK+voltage, PACK-voltage, and PACK+voltage.

[0114] In the embodiment of the present application, the adhesion detection circuit of the main negative relay needs to be connected to the front-end voltage measurement point (PACK-) and the rear-end voltage measurement point (LINK-) of the main negative relay. Among them, PACK-voltage refers to the front-end voltage of the main negative relay, that is, the negative connection summary point of the battery pack. LINK-voltage refers to the negative voltage at the rear end of the relay, that is, the negative voltage of the battery pack after it is connected to the external load or charger through the main negative relay.

[0115] Step 501, providing voltage to the adhesion detection circuit through the power supply pin of the battery controller.

[0116] Optionally, the battery controller can monitor the voltage of the battery in real time to ensure that the battery operates within a safe voltage range. In the embodiment of the present application, the model of the battery controller can be MC33772, a six-channel lithium-ion battery controller.

[0117] Optionally, the battery controller includes a power supply pin (VCOM), which is used to output a voltage signal to the adhesion detection circuit.

[0118] Optionally, the power supply pin may be connected to a front-end voltage measurement point and a rear-end voltage measurement point of the main negative relay via a sampling voltage-dividing resistor.

[0119] Step 502: lower the voltage outputted by the power supply pin by sampling the voltage-dividing resistor.

[0120] Optionally, when using a battery controller to detect the voltage of the main negative relay, a sampling voltage divider resistor can be set between the battery controller and the main negative relay. The resistor is used to divide the voltage output by the power supply pin so that the battery controller can measure the divided voltage value through the voltage measurement pin.

[0121] Step 503, obtaining a voltage measurement value through a voltage measurement pin of the battery controller, and determining a sticking state of the main negative relay based on the voltage measurement value.

[0122] Optionally, the battery controller includes multiple input / output (GPIO) pins, one of which can be configured as an ADC (Analog-to-Digital Converter) input and as a voltage measurement pin, so that the voltage in the adhesion detection circuit is measured through the voltage measurement pin of the battery controller to obtain a voltage measurement value, and then the adhesion state of the main negative relay is determined based on the voltage measurement value.

[0123] Optionally, when the main negative relay is in a non-sticky state, it means that the main negative relay is in a normal working state; when the main negative relay is in a sticky state, it means that the contacts of the main negative relay are stuck and cannot be switched normally. This situation may cause the main negative relay to remain in the "on" or "off" state, thereby causing safety hazards and equipment failures.

[0124] To sum up, in the embodiment of the present application, a battery controller and a sampling voltage-divider resistor are used to design a adhesion detection circuit of the main negative relay. The voltage is provided to the adhesion detection circuit through the power supply pin of the battery controller, and after the voltage division processing by the sampling voltage-divider resistor, the voltage measurement value is obtained through the voltage measurement pin, so as to determine the adhesion state of the main negative relay according to the voltage measurement value. This can achieve the goal of effectively detecting the adhesion state of the main negative relay while reducing the cost of the detection circuit.

[0125] The solutions shown in the above embodiments of the present application can be applied to electric vehicles. Specifically, the present application also provides an electric vehicle, which includes a main negative relay adhesion detection circuit as shown in the above embodiments.

[0126] A person skilled in the art will understand that all or part of the steps to implement the above embodiments may be accomplished by hardware or by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a disk or an optical disk, etc.

[0127] The above are only optional embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A main negative relay adhesion detection circuit, characterized in that: The circuit includes a main negative relay, a battery controller and a sampling voltage-dividing resistor, the main negative relay includes a front-end voltage measurement point and a rear-end voltage measurement point, the battery controller includes a power supply pin and a voltage measurement pin, and the voltage measurement pin is connected to the front-end voltage measurement point and the rear-end voltage measurement point; The battery controller is used to provide voltage to the adhesion detection circuit through the power supply pin; The sampling voltage-dividing resistor is used to perform voltage-dividing processing on the voltage output by the power supply pin; The battery controller is also used to obtain a voltage measurement value through the voltage measurement pin, and determine the adhesion state of the main negative relay based on the voltage measurement value.

2. The circuit according to claim 1, characterized in that The circuit includes an isolation optocoupler and a current limiting resistor, the isolation optocoupler includes a light emitting diode and a phototransistor, and the battery controller also includes a level output pin; The first resistor pin of the current limiting resistor is connected to the level output pin, the second resistor pin of the current limiting resistor is connected to the anode of the light emitting diode, and the cathode of the light emitting diode is grounded; the collector of the phototransistor is connected to the power supply pin and the voltage measurement pin, and the emitter of the phototransistor is connected to the rear-end voltage measurement point; The battery controller is used to output a high level through the level output pin to put the isolation optocoupler in a conducting state.

3. The circuit according to claim 2, characterized in that The sampling voltage-dividing resistor includes a first resistor, a second resistor and a third resistor; The first resistor pin of the first resistor is connected to the voltage measurement pin, and the second resistor pin of the first resistor is connected to the collector of the phototransistor; The first resistor pin of the second resistor is connected to the power supply pin, and the second resistor pin of the second resistor is connected to the collector of the phototransistor; The first resistor pin of the third resistor is connected to the emitter of the phototransistor, and the second resistor pin of the third resistor is connected to the rear-end voltage measurement point.

4. The circuit according to claim 3, characterized in that The battery controller is used for: When the isolation optocoupler is in an on state, obtaining the voltage measurement value through the voltage measurement pin; The sticking state of the main negative relay is determined based on the voltage measurement value and the resistance voltage division value formed by the sampling voltage division resistor.

5. The circuit according to claim 4, characterized in that The battery controller is used for: When the voltage measurement value is equal to the first resistance voltage division value, determining that the main negative relay is in a sticking state; In a case where the voltage measurement value is equal to the second resistance divided voltage value, it is determined that the main negative relay is in a non-sticking state.

6. The circuit according to claim 5, characterized in that When the main negative relay is in a sticking state, the front-end voltage measurement point and the rear-end voltage measurement point are at the same potential, and the first resistor voltage division value is the voltage value after the first resistor, the second resistor and the third resistor divide the voltage; When the main negative relay is in a non-adhesive state, the front-end voltage measurement point and the rear-end voltage measurement point are not in common, and the second resistor voltage division value is a voltage value after voltage division by the first resistor and the second resistor.

7. The circuit according to claim 3, characterized in that The circuit also includes a filter resistor and a filter capacitor; the first resistor pin of the filter resistor is connected to the voltage measurement pin, and the second resistor pin of the filter resistor is connected to the first resistor pin of the first resistor; the first capacitor pin of the filter capacitor is connected to the voltage measurement pin, and the second capacitor pin of the filter capacitor is grounded; The filter resistor and the filter capacitor are used to perform filtering processing on the adhesion detection circuit.

8. The circuit according to any one of claims 1 to 7, characterized in that: The circuit further comprises a transformer, the primary coil of the transformer is connected to the output pin of the battery controller, and the secondary coil of the transformer is connected to the communication link of the micro control unit; The battery controller is used to transmit the adhesion state signal corresponding to the main negative relay to the micro control unit through the transformer.

9. A method for detecting adhesion of a main negative relay, characterized in that: The method is used for a main negative relay adhesion detection circuit, the circuit comprising a main negative relay, a battery controller and a sampling voltage-dividing resistor, the main negative relay comprising a front-end voltage measurement point and a rear-end voltage measurement point, the battery controller comprising a power supply pin and a voltage measurement pin, the voltage measurement pin being connected to the front-end voltage measurement point and the rear-end voltage measurement point; The method comprises: Providing voltage to the adhesion detection circuit through the power supply pin of the battery controller; Reducing the voltage output by the power supply pin through the sampling voltage-dividing resistor; A voltage measurement value is obtained through the voltage measurement pin of the battery controller, and the adhesion state of the main negative relay is determined based on the voltage measurement value.

10. An electric vehicle, characterized in that: The electric vehicle comprises a main negative relay adhesion detection circuit as claimed in any one of claims 1 to 8.

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