A vehicle and a control method thereof

Abstract

The application discloses a vehicle and a control method thereof. The vehicle control method comprises the following steps: before a first switch is closed, if an absolute value of a difference between a battery voltage of a battery and a bus voltage of a bus capacitor is less than a first preset threshold, discharging the bus capacitor; if the absolute value of the difference between the battery voltage of the battery and the bus voltage of the bus capacitor is greater than or equal to the first preset threshold within a preset discharging duration, adopting a target control signal to control a grounding switch to be closed; and if the absolute value of the difference between the battery voltage of the battery and the bus voltage of the bus capacitor is less than the first preset threshold after the preset discharging duration, determining that a contactor is faulty. The application can detect whether the contactor has a fault such as contact point sticking, and avoids the contactor from being unable to be disconnected in an emergency, thereby causing a safety accident. Therefore, the application effectively improves the reliability and safety of vehicle control.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicles, in particular to a vehicle and a control method thereof. BACKGROUND

[0002] With the rapid development and increasing perfection of energy storage devices, new energy vehicles are rapidly rising.

[0003] In the prior art, new energy vehicles are mainly powered by batteries, and a controller controls the on-off of a contactor to realize power supply from the battery to a power supply circuit of the vehicle. However, if the contactor fails, the battery may not be able to normally supply power to the power supply circuit, thereby affecting the overall performance and safety of the vehicle. That is, the vehicle control method in the prior art has the problems of low reliability and poor safety. SUMMARY

[0004] The present application provides a vehicle and a control method thereof to solve the problems of low reliability and poor safety in the vehicle control method in the prior art.

[0005] According to an aspect of the present application, a vehicle control method is provided, the vehicle comprising a contactor and a controller; the contactor comprising a coil and a first switch, and the controller comprising an inverter circuit, a grounding switch and a control unit; the first switch being connected between a battery and a first busbar of the inverter circuit, and a busbar capacitor being connected between the first busbar and a second busbar of the inverter circuit; a first end of the coil being connected to the battery, a second end of the coil being grounded through the grounding switch, and the control unit being connected to a control end of the grounding switch; the vehicle control method being executed by the control unit; and the vehicle control method comprising:

[0006] before the first switch is closed, if an absolute value of a difference between a battery voltage of the battery and a busbar voltage of the busbar capacitor is less than a first preset threshold, discharging the busbar capacitor;

[0007] if the absolute value of the difference between the battery voltage of the battery and the busbar voltage of the busbar capacitor is greater than or equal to the first preset threshold within a preset discharging duration, using a target control signal to control the grounding switch to be closed;

[0008] if the absolute value of the difference between the battery voltage of the battery and the busbar voltage of the busbar capacitor is less than the first preset threshold after the preset discharging duration, determining that the contactor fails.

[0009] Optionally, the using the target control signal to control the grounding switch to be closed comprises:

[0010] if an absolute value of a difference between the battery voltage and the bus voltage of the bus capacitor is greater than or equal to a second preset threshold value, controlling the bus capacitor to charge;

[0011] if the absolute value of the difference between the battery voltage and the bus voltage of the bus capacitor is less than the second preset threshold value within a preset charging duration, controlling the bus capacitor to stop charging and outputting the target control signal to the ground switch.

[0012] Optionally, the vehicle control method further comprises:

[0013] if the absolute value of the difference between the battery voltage and the bus voltage of the bus capacitor is greater than or equal to the second preset threshold value after the preset charging duration, determining that the bus capacitor charging fails.

[0014] Optionally, the controlling the bus capacitor to discharge comprises:

[0015] controlling the bus inverter circuit to discharge to a phase winding of the vehicle motor, wherein a discharge voltage of the bus inverter circuit is less than a first preset voltage.

[0016] Optionally, after the target control signal is used to control the ground switch to close, the method further comprises:

[0017] if the controller determines that the vehicle fails or detects that the battery voltage is lower than a third preset threshold value, controlling the inverter circuit to stop outputting voltage;

[0018] controlling the ground switch to open.

[0019] Optionally, the target control signal comprises a pulse width modulation signal of a first target duty ratio and a pulse width modulation signal of a second target duty ratio.

[0020] the using the target control signal to control the ground switch to close comprises: outputting the pulse width modulation signal of the first target duty ratio to a control end of the ground switch according to a rated voltage;

[0021] after a preset closing duration, outputting the pulse width modulation signal of the second target duty ratio to the control end of the ground switch according to a maintenance voltage; wherein the maintenance voltage is less than the rated voltage.

[0022] Optionally, the first target duty ratio is a percentage corresponding to a ratio of the rated voltage to the battery voltage.

[0023] the second target duty ratio is a percentage corresponding to a ratio of the maintenance voltage to the battery voltage.

[0024] Optionally, after controlling the grounding switch to close using the target control signal, the following steps are included:

[0025] If the coil current on the coil is greater than the first preset current, the coil is determined to be short-circuited.

[0026] If the coil current on the coil is less than the second preset current, the coil is determined to be open circuit.

[0027] Optionally, after determining that the contactor is faulty, the method further includes:

[0028] The inverter circuit is controlled to stop outputting voltage to the vehicle's motor.

[0029] According to another aspect of the present invention, a vehicle is provided, the vehicle including a contactor and a controller; the contactor includes a coil and a first switch, the controller includes an inverter circuit, a grounding switch and a control unit; the first switch is connected between a battery and a first bus of the inverter circuit, and a bus capacitor is connected between the first bus and a second bus of the inverter circuit; a first end of the coil is connected to the battery, a second end of the coil is grounded through the grounding switch, and the control unit is connected to the control terminal of the grounding switch; the control unit is used to execute the vehicle control method provided in any embodiment of the present invention.

[0030] The technical solution of this invention compares the battery voltage and the bus voltage before the contactor closes. If the absolute value of the voltage difference between the battery voltage and the bus voltage is greater than or equal to a first threshold, it is determined that the contactor is not stuck, and the contactor is controlled to close. If the absolute value of the voltage difference between the battery voltage and the bus voltage is less than the first threshold, the bus capacitor is discharged. If, after a preset discharge time, the absolute value of the voltage difference between the battery voltage and the bus voltage is still less than the first threshold, the contactor is determined to be faulty, and the contactor is not closed. Therefore, this invention can detect whether there are faults such as contact sticking in the contactor before controlling the contactor to close, avoiding the contactor from closing under sticking conditions, thereby avoiding safety accidents caused by the inability to disconnect the contactor in emergency situations. Therefore, this invention effectively improves the reliability and safety of vehicle control.

[0031] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0032] In order to make the technical solution in the embodiments of the present application clearer, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0033] Figure 1 A flow chart of a vehicle control method provided by an embodiment of the present application is shown in FIG. 1.

[0034] Figure 2 A flow chart of another vehicle control method provided by an embodiment of the present application is shown in FIG. 2.

[0035] Figure 3 A flow chart of still another vehicle control method provided by an embodiment of the present application is shown in FIG. 3.

[0036] Figure 4 A structural schematic diagram of a vehicle internal circuit provided by an embodiment of the present application is shown in FIG. 4. DETAILED DESCRIPTION

[0037] In order to make the technical solution in the embodiments of the present application clearer, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0038] It should be noted that the terms "first", "second", and the like in the description of the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0039] The vehicle control method provided by the embodiment of the present application can be controlled by a control unit of a controller in a vehicle, and the controller can be a vehicle controller of the vehicle, that is, a controller for controlling the motor of the vehicle. The vehicle includes a contactor and a controller; the contactor includes a coil and a first switch, and the controller includes an inverter circuit, a grounding switch and a control unit; the first switch is connected between a battery and a first bus bar of the inverter circuit; a bus bar capacitor is connected between the first bus bar and a second bus bar of the inverter circuit; a first end of the coil is connected to the battery, and a second end of the coil is grounded through the grounding switch; and the control unit is connected to a control end of the grounding switch.

[0040] In the embodiment of the present application, the vehicle can be an electric vehicle. The vehicle can include a road vehicle or a non-road vehicle, and the non-road vehicle includes a forklift, a dumper and the like. The battery can be a lithium battery or a lead-acid battery. The battery provides power and power for the vehicle, and the control unit can control whether the coil of the contactor is electrified by controlling the on-off of the grounding switch, thereby controlling the on-off of the first switch of the contactor. For example, when the control unit controls the grounding switch to be turned on, the battery, the coil, the grounding switch and the ground wire form a loop, the battery supplies power to the coil, the coil is electrified to attract the first switch of the contactor, the first switch of the contactor is turned on, and the contactor is attracted (i.e. turned on). When the control unit controls the grounding switch to be turned off, the battery, the coil, the grounding switch and the ground wire cannot form a loop, the battery cannot supply power to the coil, the coil cannot be electrified, and the first switch of the contactor is turned off, so that the contactor is turned off. The control unit can output a pulse width modulation signal to the control end of the grounding switch, thereby controlling the on duration of the grounding switch and further controlling the average voltage of the coil. When the contactor is turned on, the battery outputs electric energy, the inverter circuit converts the direct current output by the battery into alternating current, and drives the motor of the vehicle to operate. The control unit can include a control chip, such as a single-chip microcomputer chip or a digital processing chip. The inverter circuit can include a three-phase full-bridge inverter circuit, thereby outputting three-phase voltage to the motor. The first bus bar can be connected to the positive electrode of the battery, and the second bus bar can be connected to the negative electrode of the battery; or the first bus bar can be connected to the negative electrode of the battery, and the second bus bar can be connected to the positive electrode of the battery, which is not limited in the embodiment. The battery, the first bus bar, the inverter circuit and the second bus bar can form a loop. The bus bar capacitor can include one capacitor or a plurality of capacitors, which is not limited in the embodiment.

[0041] Figure 1 A flowchart of a vehicle control method provided by the embodiment of the present application, and the embodiment can be applied to control the battery to supply power to the power supply loop of the vehicle. As shown in Figure 1 , the method comprises:

[0042] S110, before the first switch is closed, if an absolute value of a difference between the battery voltage of the battery and the bus voltage of the bus capacitor is less than a first preset threshold, the bus capacitor is controlled to discharge.

[0043] Specifically, the battery voltage refers to a voltage value between the battery of the vehicle, reflecting the battery energy state. The bus voltage refers to a voltage value between the bus capacitor. The first preset threshold refers to a value set in advance, used to determine the range of the absolute value of the difference between the battery voltage and the bus voltage. Before the first switch is closed, the first switch of the contactor is in an open state, at this time, there is no electrical connection between the battery and the bus capacitor, that is, before the motor of the vehicle runs.

[0044] In the embodiment of the application, if the absolute value of the difference between the battery voltage of the battery and the bus voltage of the bus capacitor is less than the first preset threshold, that is, the bus voltage is close to the battery voltage, it indicates that the voltage between the two ends of the first switch of the contactor is small, which may be caused by the high potential accumulated on the bus capacitor, or may be caused by the contact adhesion of the contactor, so the bus capacitor is controlled to discharge first to reduce the voltage on the bus capacitor. According to the relationship between the bus voltage and the battery voltage after the bus capacitor is discharged, it can be determined whether the contact of the contactor is adhered.

[0045] S120, if the absolute value of the difference between the battery voltage of the battery and the bus voltage of the bus capacitor is greater than or equal to the first preset threshold within the preset discharge time, the target control signal is used to control the grounding switch to be closed.

[0046] Specifically, the preset discharging duration refers to a preset duration of discharging the bus capacitor. The target control signal refers to a control signal issued by the control unit for controlling the control end of the grounding switch. Exemplarily, the target control signal can be a pulse width modulation signal. Exemplarily, the battery voltage and the bus voltage are detected every certain duration (for example, 1 ms) within the preset discharging duration, and if the absolute value of the difference between the battery voltage and the bus voltage is greater than or equal to a first preset threshold, the grounding switch is controlled to be closed by using the target control signal, the coil is powered, and the first switch is closed. For example, after the discharging is started, the discharging judgment period is entered, the battery voltage and the bus voltage are collected, and if the absolute value of the difference between the battery voltage and the bus voltage is greater than or equal to the first preset threshold, it is confirmed that the contacts of the contactor are not stuck, and the discharging is stopped. If the absolute value of the difference between the battery voltage and the bus voltage is less than the first preset threshold, the discharging count value is increased by one, the discharging is continued, and in the next discharging judgment period, it is continued to judge whether the absolute value of the difference between the battery voltage and the bus voltage is greater than or equal to the first preset threshold; the judgment is repeated, and if until the discharging count value is greater than the ratio of the preset discharging duration to the discharging judgment period duration, the absolute value of the difference between the battery voltage and the bus voltage is still less than the first preset threshold, it is considered that the contacts of the contactor are stuck, and it is confirmed that the contactor is faulty. The discharging judgment period duration can be 1 ms. In addition, after the discharging is stopped, the discharging count value can be set to zero.

[0047] In the embodiment of the application, if the absolute value of the difference between the battery voltage and the bus voltage is less than or equal to the first preset threshold within the preset discharging duration, it is indicated that the electric energy accumulated on the bus capacitor has been released, and it is determined that the contacts of the contactor are not stuck. The voltage difference between the two ends of the contactor contacts satisfies the closing condition, so the grounding switch is controlled to be closed, the coil of the contactor is powered, and then the first switch is controlled to be closed.

[0048] S130, if the absolute value of the difference between the battery voltage of the battery and the bus voltage of the bus capacitor is less than the first preset threshold after the preset discharging duration, it is determined that the contactor is faulty.

[0049] Exemplarily, the contactor fault can be that the contacts of the contactor are stuck, and the contacts being stuck can be caused by an electric arc generated in the process of load breaking or attraction of the contactor, or can be caused by mechanical aging.

[0050] In the embodiment of the present application, if the absolute value of the difference between the battery voltage and the bus voltage is still less than the first preset threshold after the bus capacitor is discharged for the preset discharging duration, it is determined that the contactor fails, because the voltage difference between the two contacts is too small and is not caused by the accumulated potential of the bus capacitor, but caused by the contactor failure. In this way, the contactor can be detected before the contactor is controlled to be closed, so that the contactor can be prevented from being closed in the case of contact sticking, and the contactor can be quickly disconnected in an emergency, thereby effectively preventing safety accidents and improving the reliability and safety of vehicle control.

[0051] The technical scheme of the embodiment of the present application compares the battery voltage and the bus voltage before the contactor is closed. If the absolute value of the voltage difference between the battery voltage and the bus voltage is greater than or equal to the first threshold, it is determined that the contactor does not stick, and the contactor is controlled to be closed. If the absolute value of the voltage difference between the battery voltage and the bus voltage is less than the first threshold, the bus capacitor is discharged. If the absolute value of the voltage difference between the battery voltage and the bus voltage is still less than the first threshold after the bus capacitor is discharged for the preset discharging duration, it is determined that the contactor fails, and the contactor is not closed. Therefore, the present application can detect whether the contactor has a fault such as contact sticking before the contactor is controlled to be closed, so that the contactor can be prevented from being closed in the case of contact sticking, thereby avoiding the failure of the contactor to be disconnected in an emergency and causing a safety accident. Therefore, the present application effectively improves the reliability and safety of vehicle control.

[0052] On the basis of the above technical scheme, the discharging of the bus capacitor can be controlled, including: controlling the bus inverter circuit to discharge to one phase winding of the vehicle motor, wherein the discharging voltage of the bus inverter circuit is less than the first preset voltage.

[0053] Specifically, the first preset voltage refers to a preset maximum voltage to ensure that the motor does not work. The discharging voltage less than the first preset voltage can ensure that the motor does not run when the bus capacitor is discharged, and can effectively prevent the motor winding from being impacted by a high voltage, thereby avoiding damage to the motor and its driving circuit.

[0054] For example, the inverter circuit can output a three-phase voltage, and a phase branch of the inverter circuit and a phase winding of the motor form a discharge circuit. The controller (control unit) controls the on time of the switch tube in the inverter circuit through a pulse width modulation signal (PWM) to control the output power of the inverter circuit. When the controller controls the on time of the switch tube corresponding to the output voltage of one phase of the inverter circuit, the bus capacitor discharges to the phase winding of the motor through the switch tube corresponding to the output voltage of one phase of the inverter circuit. In this way, an additional discharge circuit can be omitted, thereby reducing the cost and simplifying the circuit design. However, the duty cycle of the control signal corresponding to the inverter circuit cannot be too large, otherwise the motor will malfunction, that is, the discharge voltage must be less than the first preset voltage.

[0055] Figure 2 Another flowchart of a vehicle control method provided by an embodiment of the application is shown in FIG. 10, which is based on the above-mentioned embodiments. As shown in FIG. 10, the method comprises the following steps. Figure 2

[0056] S210, before the first switch is closed, if the absolute value of the difference between the battery voltage and the bus voltage of the bus capacitor is less than a first preset threshold, the bus capacitor is controlled to discharge.

[0057] S220, if the absolute value of the difference between the battery voltage and the bus voltage of the bus capacitor is greater than or equal to the first preset threshold within a preset discharge time.

[0058] S230, if the absolute value of the difference between the battery voltage and the bus voltage of the bus capacitor is greater than or equal to a second preset threshold, the bus capacitor is controlled to charge.

[0059] Specifically, the second preset threshold refers to another value preset for judging the range of the absolute value of the difference between the battery voltage and the bus voltage.

[0060] In the embodiment of the application, if the absolute value of the difference between the battery voltage and the bus voltage is greater than the second preset threshold, it indicates that the voltage difference between the two ends of the first switch of the contactor is too large, that is, the bus voltage of the bus capacitor is too small. By charging the bus capacitor, the bus voltage can be increased, the absolute value of the difference between the battery voltage and the bus voltage can be reduced, the voltage difference between the two ends of the first switch can be reduced, and the overlarge current generated at the moment when the contactor is closed can be avoided, thereby preventing the contactor from being damaged.

[0061] S240, if the absolute value of the difference between the battery voltage and the bus voltage of the bus capacitor is less than the second preset threshold within a preset charging time, the bus capacitor is controlled to stop charging, and a target control signal is output to the grounding switch.

[0062] ​The preset charging duration refers to a duration of charging the bus capacitor in advance.

[0063] For example, during the preset charging duration, the battery voltage and the bus voltage are collected every certain duration (e.g., 1 ms), and if the absolute value of the difference between the battery voltage and the bus voltage is less than the second preset threshold, the charging of the bus capacitor is stopped.

[0064] For example, after the charging is started, the battery voltage and the bus voltage are collected in a charging judgment period, and if the absolute value of the difference between the battery voltage and the bus voltage is less than the second preset threshold, the charging of the bus capacitor is stopped. If the absolute value of the difference between the battery voltage and the bus voltage is greater than or equal to the second preset threshold, the charging count value is increased by one, and the charging is continued. In the next charging judgment period, it is continuously judged whether the absolute value of the difference between the battery voltage and the bus voltage is less than the second preset threshold. If the absolute value of the difference between the battery voltage and the bus voltage is still greater than or equal to the second preset threshold until the charging count value is greater than the ratio of the preset charging duration to the duration of the charging judgment period, it is determined that the charging process of the bus capacitor fails. The duration of the charging judgment period can be 1 ms. After the charging of the bus capacitor is stopped, the charging count value can be reset to zero, so as to facilitate the charging judgment next time.

[0065] In the embodiment of the application, when the absolute value of the voltage difference between the battery voltage and the bus voltage is greater than or equal to the first preset threshold and less than the second preset threshold, the grounding switch is closed, the coil is powered, and the first switch of the contactor is closed. In this way, when the absolute value of the voltage difference between the battery voltage and the bus voltage is greater than or equal to the first preset threshold, it can be ensured that the contacts of the contactor are not stuck, and when the absolute value of the voltage difference between the battery voltage and the bus voltage is less than the second preset threshold, it can be ensured that the contactor will not be damaged due to arc discharge, excessive instantaneous current, etc. during the closing process.

[0066] S250, if the absolute value of the difference between the battery voltage of the battery and the bus voltage of the bus capacitor is less than the first preset threshold after the preset discharging duration, it is determined that the contactor fails.

[0067] Optionally, the vehicle control method further comprises:

[0068] If the absolute value of the difference between the battery voltage of the battery and the bus voltage of the bus capacitor is greater than or equal to the second preset threshold after the preset charging duration, it is determined that the bus capacitor charging fails.

[0069] In the embodiment of the application, if the absolute value of the difference between the battery voltage and the bus voltage is still greater than the second preset threshold after the preset charging duration, it is determined that the charging fails, which indicates that the bus capacitor charging fails, such as aging, damage or internal short circuit of the bus capacitor, etc. Therefore, timely maintenance should be performed to avoid safety hazards.

[0070] The technical scheme of the embodiment of the application can avoid damage of the contactor due to excessive instantaneous current and improve the reliability and stability of the contactor by ensuring that the first switch of the contactor is closed when the absolute value of the voltage difference between the battery voltage and the capacitor voltage is less than the second preset threshold.

[0071] Optionally, after the ground switch is controlled to be closed by the target control signal, the method further comprises: if the controller determines that the vehicle is faulty or detects that the battery voltage is lower than a third preset threshold, controlling the inverter circuit to stop outputting voltage; and controlling the ground switch to be opened.

[0072] Specifically, the vehicle fault refers to any fault or abnormal condition of the normal operation of the vehicle, such as problems in the transmission system, the electrical system, the power system, etc., for example, uncontrolled motor, which may cause safety hazards or performance degradation of the vehicle. The third preset threshold refers to a critical value of the battery voltage. In the embodiment of the application, the control unit monitors the battery voltage of the vehicle in real time. If it is detected that the battery voltage drops below the third preset threshold, it is determined that the vehicle is being turned off by the key, and the inverter circuit is immediately controlled to stop outputting voltage, the load (motor) is disconnected, and the ground switch is controlled to be opened, so that the coil of the contactor loses power and the first switch of the contactor is opened.

[0073] In the embodiment of the application, if a vehicle fault or a battery output voltage drop is found, the inverter circuit is controlled to stop outputting voltage to the motor of the vehicle in time, and the ground switch is opened, so that the contactor coil cannot be powered, the first switch of the contactor is opened, and the battery stops delivering power, thereby ensuring that the contactor is not disconnected under load, protecting the safety of the vehicle and personnel, and reducing the possibility of fire and electric shock.

[0074] Optionally, the target control signal includes a pulse width modulation signal of a first target duty cycle and a pulse width modulation signal of a second target duty cycle.

[0075] Figure 3 Another flowchart of a vehicle control method provided by the embodiment of the application is based on the above-mentioned embodiments, and as shown in FIG. 8, the method comprises: Figure 3

[0076] S310, before the first switch is closed, if the absolute value of the difference between the battery voltage of the battery and the bus voltage of the bus capacitor is less than a first preset threshold, the bus capacitor is controlled to be discharged.

[0077] S320, if the absolute value of the difference between the battery voltage of the battery and the bus voltage of the bus capacitor is greater than or equal to the first preset threshold within a preset discharging time.

[0078] ​S330, output a pulse width modulation signal with a first target duty ratio to the control end of the grounding switch according to the rated voltage.

[0079] Specifically, the rated voltage refers to the voltage that should be met when the contactor coil is specified for the attraction action. The pulse width modulation signal refers to a technology that transmits information or controls power output by modulating the width (duty ratio) of the pulse signal. The control unit can output the pulse width modulation signal to the control end of the grounding switch, thereby controlling the conduction time of the grounding switch and further controlling the average voltage of the coil. The pulse width modulation signal with the first target duty ratio refers to the control signal sent by the control unit to the control end of the grounding switch according to the rated voltage, for making the voltage of the coil of the contactor sufficient to drive the first switch to attract. The greater the first target duty ratio, the longer the conduction time of the grounding switch, and the greater the potential accumulated on the coil. By outputting the pulse width modulation signal with the first target duty ratio to the control end of the grounding switch, the average voltage of the coil can be controlled to reach the rated voltage, thereby ensuring that the contactor can reliably attract.

[0080] Optionally, the first target duty ratio is a percentage corresponding to the ratio of the rated voltage to the battery voltage.

[0081] Specifically, the calculation formula of the first target duty ratio is:

[0082] The first target duty ratio = (rated voltage / battery voltage) * 100%.

[0083] In the embodiment of the application, the voltage across the contactor coil is adjusted by adjusting the conduction time of the grounding switch, so that the first switch of the contactor can be reliably switched from the open state to the attracted state.

[0084] S340, output a pulse width modulation signal with a second target duty ratio to the control end of the grounding switch according to the maintenance voltage after a preset attraction time; wherein the maintenance voltage is less than the rated voltage.

[0085] Specifically, the maintenance voltage refers to the voltage across the coil that can maintain the first switch in the attracted state. The pulse width modulation signal with the second target duty ratio refers to another control signal sent by the control unit to the control end of the grounding switch according to the rated voltage, for making the voltage across the coil sufficient to maintain the first switch in the attracted state. After determining that the first switch is stably attracted, the rated voltage is reduced to the maintenance voltage, which can reduce the power consumption and heat generation of the contactor.

[0086] In addition, optionally, after outputting the pulse width modulation signal with the second target duty ratio to the control end of the grounding switch according to the maintenance voltage, the vehicle control method further comprises:

[0087] The actual battery voltage is acquired in real time or periodically, and a second target duty cycle of the pulse width modulation signal output by the control unit is determined according to the actual battery voltage and the maintenance voltage.

[0088] Specifically, based on the battery characteristics, when the load of the vehicle is large, the battery voltage will decrease, and when the load of the vehicle is small, the battery voltage will increase, so the battery voltage is not a stable value. By acquiring the actual battery voltage in real time or periodically, the second target duty cycle of the pulse width modulation signal output by the control unit can be determined in real time or periodically according to the actual battery voltage and the maintenance voltage, so as to ensure the voltage applied to the contactor coil and enable the contactor to be stably attracted.

[0089] Optionally, the second target duty cycle is a percentage corresponding to the ratio of the maintenance voltage to the battery voltage.

[0090] Specifically, the calculation formula of the second target duty cycle is:

[0091] The second target duty cycle = (maintenance voltage / battery voltage) * 100%.

[0092] In the embodiment of the application, after the coil stably attracts the first switch, the duty cycle of the pulse width modulation signal output by the control unit is adjusted to reduce the rated voltage to the maintenance voltage, so as to reduce the power consumption and heat generation of the contactor.

[0093] S350, if the absolute value of the difference between the battery voltage of the battery and the bus voltage of the bus capacitor is less than the first preset threshold after the preset discharging duration, it is determined that the contactor is faulty.

[0094] The technical scheme of the embodiment of the application adjusts the voltage across the contactor coil by adjusting the duty cycle of the control end of the grounding switch, so that the first switch of the contactor can be reliably attracted when the coil voltage is the rated voltage, and the state of stable attraction can be maintained under the action of the maintenance voltage after attraction, thereby effectively reducing the power consumption and heat generation of the contactor and improving the reliability and stability of the contactor.

[0095] On the basis of the above-mentioned embodiments, optionally, after the grounding switch is controlled by the target control signal, the method further comprises: if the coil current on the coil is greater than a first preset current, it is determined that the coil is short-circuited; and if the coil current on the coil is less than a second preset current, it is determined that the coil is open-circuited.

[0096] Specifically, the first preset current refers to a preset current threshold, and when the coil current exceeds the first preset current, it is proved that the coil is short-circuited. The second preset current refers to another preset current threshold, and when the coil current is less than the first preset current, it is proved that the coil is open-circuited.

[0097] In the embodiment of the present application, the current in the coil is collected in real time, and if the coil current is too large and exceeds the first preset current, it is determined that the coil is short-circuited, and if the coil current is too small and is less than the second preset current, it is determined that the coil is open-circuited.

[0098] The technical scheme of the embodiment of the present application determines whether the coil of the contactor is short-circuited or open-circuited by monitoring the current flowing in the coil, so that the contactor fault can be found in time, the electrical accident caused by the coil short-circuit or open-circuit is avoided, the safe operation of the vehicle is ensured, and the risk of vehicle damage and personnel injury is reduced.

[0099] On the basis of the above-mentioned embodiments, after determining the contactor fault, the method further comprises: controlling the inverter circuit to stop outputting the voltage to the motor of the vehicle.

[0100] For example, the contactor fault can include contact adhesion of the contactor.

[0101] In the embodiment of the present application, if it is determined that the contactor is faulty, stopping the voltage output can prevent the motor from continuing to operate in the fault state, and avoid electrical damage or larger-scale failure caused by motor overload or short-circuit.

[0102] The technical scheme of the embodiment of the present application prevents the battery from continuing to supply power to the motor in the case of contactor failure by stopping the output of the voltage, effectively avoids further damage to the vehicle, and improves the reliability and safety of the vehicle.

[0103] The embodiment of the present application also provides a vehicle, Figure 4 For the structure schematic diagram of the internal circuit of the vehicle provided by the embodiment of the present application, reference is made to Figure 4 The vehicle comprises a contactor 110 and a controller 120; the contactor 110 comprises a coil 111 and a first switch 112, and the controller 120 comprises an inverter circuit 121, a grounding switch 122 and a control unit 123; the first switch 112 is connected between a battery 130 and a first bus bar 124 of the inverter circuit 121, a bus bar capacitor 140 is connected between the first bus bar 124 and a second bus bar 125 of the inverter circuit 121; a first end of the coil 111 is connected to the battery 130, a second end of the coil 111 is grounded through the grounding switch 122, and a control end of the grounding switch 122 is connected to the control unit 123; the control unit 123 is used to execute the vehicle control method provided by any embodiment of the present application, and has the function modules and beneficial effects corresponding to the execution method. The vehicle can further comprise a motor, the inverter circuit 121 is connected to the motor, and the inverter circuit 121 provides the voltage for the motor.

[0104] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0105] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A vehicle control method, characterized in that, The vehicle includes a contactor and a controller; the contactor includes a coil and a first switch, the controller includes an inverter circuit, a grounding switch and a control unit; the first switch is connected between the battery and the first bus of the inverter circuit, and a bus capacitor is connected between the first bus and the second bus of the inverter circuit; the first end of the coil is connected to the battery, the second end of the coil is grounded through the grounding switch, and the control unit is connected to the control terminal of the grounding switch; The vehicle control method is executed by the control unit; The vehicle control method includes: Before the first switch is closed, if the absolute value of the difference between the battery voltage of the battery and the bus voltage of the bus capacitor is less than a first preset threshold, then the bus capacitor is controlled to discharge. If, within a preset discharge duration, the absolute value of the difference between the battery voltage of the battery and the bus voltage of the bus capacitor is greater than or equal to the first preset threshold, then the target control signal is used to control the grounding switch to close. If, after the preset discharge time, the absolute value of the difference between the battery voltage of the battery and the bus voltage of the bus capacitor is less than the first preset threshold, then it is determined that the contactor has a contact sticking fault. The method of controlling the grounding switch to close using a target control signal includes: If the absolute value of the difference between the battery voltage and the bus voltage of the bus capacitor is greater than or equal to a second preset threshold, then the bus capacitor is controlled to charge. If, within a preset charging time, the absolute value of the difference between the battery voltage of the battery and the bus voltage of the bus capacitor is less than the second preset threshold, then the bus capacitor is controlled to stop charging, and the target control signal is output to the grounding switch. The vehicle control method further includes: if, after the preset charging time, the absolute value of the difference between the battery voltage of the battery and the bus voltage of the bus capacitor is greater than or equal to the second preset threshold, then the bus capacitor charging fault is determined.

2. The vehicle control method according to claim 1, characterized in that, The control of the bus capacitor discharge includes: The inverter circuit is controlled to discharge to one phase winding of the vehicle motor, wherein the discharge voltage of the inverter circuit is less than a first preset voltage.

3. The vehicle control method according to claim 1, characterized in that, After controlling the grounding switch to close using the target control signal, the method further includes: If the controller determines that the vehicle is faulty, or detects that the battery voltage is lower than a third preset threshold, it controls the inverter circuit to stop outputting voltage. The grounding switch is disconnected.

4. The vehicle control method according to claim 1, characterized in that, The target control signal includes a pulse width modulation signal of a first target duty cycle and a pulse width modulation signal of a second target duty cycle; The method of controlling the grounding switch to close using a target control signal includes: According to the rated voltage, output a pulse width modulation signal with the first target duty cycle to the control terminal of the grounding switch; After a preset engagement time, a pulse width modulation signal with a second target duty cycle is output to the control terminal of the grounding switch according to the sustaining voltage; wherein the sustaining voltage is less than the rated voltage.

5. The vehicle control method according to claim 4, characterized in that, The first target duty cycle is a percentage corresponding to the ratio of the rated voltage to the battery voltage; The second target duty cycle is a percentage corresponding to the ratio of the sustaining voltage to the battery voltage.

6. The vehicle control method according to claim 1, characterized in that, After the grounding switch is closed by controlling it with the target control signal, the following steps are included: If the coil current on the coil is greater than the first preset current, the coil is determined to be short-circuited. If the coil current on the coil is less than the second preset current, the coil is determined to be open circuit.

7. The vehicle control method according to claim 1, characterized in that, After determining that the contactor is faulty, the following steps are also included: The inverter circuit is controlled to stop outputting voltage to the vehicle's motor.

8. A vehicle, characterized in that, The vehicle includes a contactor and a controller; the contactor includes a coil and a first switch, and the controller includes an inverter circuit, a grounding switch, and a control unit; the first switch is connected between the battery and the first bus of the inverter circuit, and a bus capacitor is connected between the first bus and the second bus of the inverter circuit; the first end of the coil is connected to the battery, the second end of the coil is grounded through the grounding switch, and the control unit is connected to the control terminal of the grounding switch; the control unit is used to execute the vehicle control method according to any one of claims 1-7.

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