Power-on and power-off control device and method for large-tonnage pure electric mining truck

Abstract

The invention discloses a power-on and power-off control device and method for a large-tonnage pure electric mining truck. The device comprises a whole vehicle controller, a battery management system, a high-voltage box and a frequency conversion control cabinet, the whole vehicle controller is communicated with the frequency conversion control cabinet through a whole vehicle CAN bus, the battery management system is communicated with the high-voltage box through a battery CAN, and the frequency conversion control cabinet is connected with the battery management system through a high-voltage bus. The device is further integrated with a direct-current converter used for voltage conversion and CAN bus data forwarding. The method comprises a power-on process and a power-off process, wherein low-voltage self-checking, high-voltage pre-charging, bus voltage building and equipment starting are sequentially executed during power-on; in the power-off process, equipment shutdown, high-voltage disconnection and bus active discharging are sequentially executed, and an emergency power-off mechanism is arranged. According to the invention, safe power-on and power-off management of the multi-battery pack system is realized, and the extremely cold environment adaptability and the system reliability are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of large engineering machinery equipment, and particularly relates to an on-off control device and method for a large-tonnage pure electric mine truck. BACKGROUND

[0002] As an important equipment for mine transportation, the large-tonnage pure electric mine electric drive dump truck has many advantages such as zero emission, low noise, less maintenance, good operation economy, and is one of the main directions of the green and intelligent development of mine equipment. With the increasing of environmental protection consciousness and the increasing demand of mine enterprises for operation cost control, the popularization and application of pure electric mine trucks has become an industry trend.

[0003] However, the large-tonnage pure electric mine truck still faces many technical problems in the process of research and application. At present, the manufacturing cost of the large-tonnage pure electric mine truck is high, one of the main reasons is that the power system generally adopts a multi-battery parallel structure, but lacks a mature and reliable on-off control strategy matched therewith, especially in the application scenarios of multi-battery parallel on-off process and battery group and DC / DC converter series cooperation, a systematic safety control scheme has not been formed. In addition, in the extremely cold working condition, the heat preservation performance of the power battery directly affects the starting and running efficiency of the vehicle, and the effective thermal management measures for this problem in the prior art are still insufficient, which restricts the adaptability and reliability of the vehicle in harsh environment. SUMMARY

[0004] In view of the above problems, the present application provides an on-off control device and method for a large-tonnage pure electric mine truck, which realizes safe and reliable on-off management of a multi-battery group system through a multi-system cooperative control architecture with a vehicle controller as the core, and solves the problem of battery heat preservation in extremely cold environment by cooperating with a complete control process including pre-charge protection, active discharge and emergency power-off.

[0005] In the first aspect, the present application provides an on-off control device for a large-tonnage pure electric mine truck, comprising: a vehicle controller for energy management of a power battery, on-off and charging control of a vehicle; a battery management system for real-time detection of voltage, current and temperature of the power battery, fault diagnosis and protection of the power battery, and negative control of a high-voltage loop of the battery; a high-voltage box for relay control, adhesion detection and insulation detection of a high-voltage bus loop of the battery; a frequency conversion control cabinet for controlling the work of a vehicle fan, a traction frequency converter and a brake resistor box; The vehicle controller and the frequency conversion control cabinet communicate through a vehicle CAN bus, the battery management system and the high-voltage box communicate through a battery CAN, and the frequency conversion control cabinet and the battery management system are connected through a high-voltage bus.

[0006] Further, the battery management system is also connected with a battery heating system and a battery cooling system through the battery CAN, for heating and keeping warm or cooling and dissipating heat of the power battery according to the temperature detected by the battery management system.

[0007] By automatically heating and keeping warm or cooling and dissipating heat of the power battery according to the temperature data monitored by the battery management system in real time, the performance degradation of the power battery in extremely cold environment and the overheating damage of the power battery in high-temperature environment are effectively solved, so as to guarantee the working efficiency, safety and service life of the battery, and improve the adaptability and reliability of the mine truck in harsh working conditions.

[0008] Further, the device further comprises: An emergency stop switch for vehicle high-voltage power-off emergency stop operation when an emergency occurs; A mode selection switch for selection of vehicle power-on mode, including driving mode power-on and keeping warm mode power-on; The emergency stop switch and the mode selection switch are connected with the vehicle controller through a hard wire.

[0009] The emergency stop switch ensures that the driver can trigger rapid power-off through the most direct and reliable hard-wire signal in case of sudden danger, greatly improving the safety response level of the system. The mode selection switch enables the vehicle to select different power-on strategies according to actual needs (such as driving or standing keeping warm), realizes intelligent management and reasonable allocation of energy, and avoids unnecessary energy consumption during non-working periods.

[0010] Further, the frequency conversion control cabinet is integrated with a traction frequency converter, a brake resistor chopping unit, a fan frequency converter and a charger, which are respectively used for controlling the traction motor, the brake resistor box, the vehicle fan and realizing low-voltage charging.

[0011] Further, the frequency conversion control cabinet is also integrated with a DC converter, which is used for voltage conversion between the battery high-voltage loop and the vehicle high-voltage loop, and data forwarding of the battery CAN bus and the vehicle CAN bus; the DC converter is connected with the battery management system and the traction frequency converter through a high-voltage wire harness.

[0012] The introduction of a direct current converter (DC / DC) as a key hub brings double benefits. At the power level, the safe voltage conversion and energy transmission between the high-voltage loop of the power battery and the high-voltage loop of the whole vehicle are realized. At the information level, the gateway between the battery CAN and the whole vehicle CAN is served, the seamless forwarding and network isolation of data are realized, the load rate of each CAN bus channel is effectively reduced, and the stability and real-time performance of the control system communication are ensured.

[0013] Further, the relay includes a main positive relay, a main negative relay and a pre-charge relay.

[0014] The main loop is controlled by the on-off control of the main positive relay and the main negative relay, and the pre-charge relay is used to realize the pre-charge of the high-voltage capacitor, which effectively avoids the huge impact current generated when the main loop is closed, protects the capacitors, relays and other key components in the high-voltage system, and significantly improves the safety of the high-voltage power-on process and the system life.

[0015] In a second aspect, the application also provides an up and down power control method for a large-tonnage pure electric mining truck, including an up power flow and a down power flow. The up power flow specifically includes: The driver closes the low-voltage power supply switch, the key switch is turned to the ON position, and the vehicle controller, the battery management system, the high-voltage box and the direct current converter are awakened. Each controller performs low-voltage self-checking, and then enters the up high-voltage flow. The vehicle controller judges that the mode selection switch is in the driving mode, judges that the up high-voltage condition is met, and sends a Ready signal. The key switch is turned to the START position, and the vehicle controller sends an up high-voltage instruction to the direct current converter. The direct current converter sends an up high-voltage instruction to the battery management system, the battery management system closes the main negative contactor and feeds back an HV closed signal. The direct current converter detects that the manual maintenance switch MSD is closed and the main positive relay is not stuck, and then closes the main positive relay. The direct current converter detects that the pre-charge relay is not stuck, and then closes the pre-charge relay. When the battery high-voltage bus voltage reaches a preset proportion of the battery voltage, the main variable relay is closed after a delay. The pre-charge relay is opened, and the direct current converter is started to build voltage for the high-voltage bus of the whole vehicle. After the voltage is built successfully, the vehicle controller wakes up the frequency conversion control cabinet and starts the auxiliary equipment. The down power flow specifically includes: The key switch is turned back to the ON gear, and the vehicle controller enters the down power flow. The vehicle controller sends a shutdown signal to the frequency conversion control cabinet, and the auxiliary equipment is shut down. The whole vehicle controller sends a high voltage instruction to the direct current converter; The direct current converter stops, stops building the whole vehicle high voltage bus, disconnects the main variable relay after judging that the battery current is less than a preset threshold, and sends a high voltage instruction to the battery management system after a delay; The battery management system disconnects the main negative relay and feeds back an HV open signal to the direct current converter; The frequency conversion control cabinet drives the braking resistor box to work, so that the whole vehicle high voltage bus and the battery high voltage bus are actively discharged.

[0016] Further, the power-off process further comprises an emergency power-off process: When an emergency stop switch is triggered or a high voltage fault is detected, the direct current converter stops, the whole vehicle controller sends a stop signal to the frequency conversion control cabinet, and the auxiliary equipment stops; The direct current converter disconnects the main variable relay and the main positive relay; The high voltage instruction is sent to the battery management system, and the frequency conversion control cabinet drives the braking resistor box to work, so that the whole vehicle high voltage bus and the battery high voltage bus are actively discharged.

[0017] When an emergency or serious fault is triggered, the system can bypass part of the normal judgment condition, execute the stop, disconnect the high voltage and actively discharge in the fastest path, and maximize the duration of the dangerous state, so as to provide the ultimate protection for the driver and the equipment in the extreme case, and further strengthen the intrinsic safety of the mine truck, a heavy equipment.

[0018] Compared with the prior art, the present application has the beneficial effects that: a complete, safe and efficient power-on and power-off control solution for large-tonnage pure electric mine trucks is provided, and the defects of immature control strategy, poor adaptability to extremely cold environments and insufficient system stability in the prior art are effectively overcome. First, through the unified coordination of the whole vehicle controller, a multi-level safety control process including normal power-on and power-off and emergency power-off is constructed, the power-on process adopts strict sequential control and sticking detection, and a pre-charging mechanism is introduced to effectively suppress the inrush current, and the power-off process completely eliminates the high voltage residue through active discharge, which significantly improves the system safety. Secondly, the battery management system and the multi-mode selection function are integrated, so that the vehicle can intelligently adjust the running state according to the environmental temperature and the working condition demand, effectively solving the performance degradation and heat preservation problem of the power battery in extremely cold areas, and enhancing the environmental adaptability. Then, a layered CAN network architecture with a direct current converter as a gateway is adopted, which effectively isolates and cooperatively manages the whole vehicle CAN and multiple battery CAN, greatly reduces the load rate of a single bus, and ensures the real-time performance and stability of data communication in a complex system. Through the optimized system architecture and intelligent control strategy, the present application realizes the safe, reliable and intelligent power-on and power-off management of the high voltage system of the mine truck, and the comprehensive performance is significantly better than that of the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required to be used in the description of the embodiments or the prior art will be briefly introduced. 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 based on the drawings shown.

[0020] Figure 1 A communication network connection architecture diagram of the power-on and power-off control device of the large-tonnage pure electric mine truck of the present application; Figure 2 A high-voltage circuit connection schematic diagram of the power-on and power-off control device of the large-tonnage pure electric mine truck of the present application; Figure 3 A power-on flowchart of the present application; Figure 4 A power-off flowchart of the present application. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application will be described and explained in the following with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application. Based on the embodiments provided by the present application, all other embodiments obtained by those skilled in the art without creative effort fall within the scope of the present application.

[0022] The present application provides a power-on and power-off control device of a large-tonnage pure electric mine truck, as shown in Figure 1 , 2 , specifically comprising: A vehicle controller VCU for responsible for vehicle driving control, vehicle driving system and power battery energy management, vehicle power-on and power-off and charging control, CAN network management, fault diagnosis and processing, vehicle state monitoring.

[0023] A battery management system BMS including a group A power battery management system BMSA, a group B power battery management system BMSB, a group C power battery management system BMSC, a group D power battery management system BMSD, a group E power battery management system BMSE, and a group F power battery management system BMSF for real-time detection of voltage, current and temperature of the power battery, fault diagnosis and protection of the power battery, and negative control of the battery high-voltage loop.

[0024] Battery heating system PTC, including group A power battery heating system PTC A, group B power battery heating system PTC B, group C power battery heating system PTC C, group D power battery heating system PTC D, group E power battery heating system PTC E, group F power battery heating system PTC F, used for heating and keeping warm the power battery.

[0025] Battery cooling system TMS, including group A power battery cooling system TMS A, group B power battery cooling system TMS B, group C power battery cooling system TMS C, group D power battery cooling system TMS D, group E power battery cooling system TMS E, group F power battery cooling system TMS F, used for cooling and heat dissipation of the power battery.

[0026] High-voltage box PDU, including group A high-voltage box PDU A, group B high-voltage box PDU B, group C high-voltage box PDU C, group D high-voltage box PDU D, group E high-voltage box PDU E, group F high-voltage box PDU F, used for relay control, adhesion detection and insulation detection of the battery high-voltage bus loop.

[0027] Frequency conversion control cabinet, used for controlling the working of vehicle fan, traction frequency converter and brake resistance box, and integrated with: Traction frequency converter, used for driving and controlling traction motor, realizing the driving and braking energy recovery of the vehicle; Brake resistance chopping unit, used for controlling the working of brake resistance box and consuming excess electric energy; Fan frequency converter, used for controlling the rotating speed of vehicle fan and realizing intelligent temperature control management; 24V charger, used for converting high-voltage direct current into low-voltage direct current to supply power for the vehicle; Direct current converter DC\DC, including group A bidirectional direct current converter DC\DC A, group B bidirectional direct current converter DC\DC B, group C bidirectional direct current converter DC\DC C, group D bidirectional direct current converter DC\DC D, group E bidirectional direct current converter DC\DC E, group F bidirectional direct current converter DC\DC F, used for voltage conversion between battery high-voltage loop and whole vehicle high-voltage loop, and data forwarding of battery CAN bus and whole vehicle CAN bus.

[0028] Emergency stop switch, used for vehicle high-voltage power-off emergency stop operation in emergency.

[0029] Mode selection switch, used for selection of vehicle power-on mode, including driving mode power-on and keeping warm mode power-on.

[0030] The vehicle controller VCU, the frequency conversion control cabinet, the A group bidirectional DC converter DC\DCA, the B group bidirectional DC converter DC\DCB, the C group bidirectional DC converter DC\DCC, the D group bidirectional DC converter DC\DCD, the E group bidirectional DC converter DC\DCE and the F group bidirectional DC converter DC\DCF are communicated through a vehicle CAN bus.

[0031] The A group power battery management system BMSA, the A group power battery heating system PTCA, the A group power battery cooling system TMSA and the A group high voltage box PDUA are communicated through an A group battery CAN; the B group power battery management system BMSB, the B group power battery heating system PTCB, the B group power battery cooling system TMSB and the B group high voltage box PDUB are communicated through a B group battery CAN; the C group power battery management system BMSC, the C group power battery heating system PTCC, the C group power battery cooling system TMSC and the C group high voltage box PDUC are communicated through a C group battery CAN; the D group power battery management system BMSD, the D group power battery heating system PTCD, the D group power battery cooling system TMSD and the D group high voltage box PDUD are communicated through a D group battery CAN; the E group power battery management system BMSE, the E group power battery heating system PTCE, the E group power battery cooling system TMSE and the E group high voltage box PDUE are communicated through an E group battery CAN; and the F group power battery management system BMSF, the F group power battery heating system PTCF, the F group power battery cooling system TMSF and the F group high voltage box PDUF are communicated through an F group battery CAN.

[0032] The vehicle controller VCU is connected with an emergency stop switch and a mode selection switch through a hard wire; the bidirectional DC converter DC\DC is connected with a battery management system BMS and a traction frequency converter TCU through a high voltage wire harness, and a start-up and shutdown control method of the large tonnage pure electric mine truck is adopted for control.

[0033] The application further provides a start-up and shutdown control method of a large tonnage pure electric mine truck, which is realized based on the start-up and shutdown control device of the large tonnage pure electric mine truck and comprises a start-up process and a shutdown process.

[0034] Specifically, as shown in the figure, Figure 3 the start-up process is as follows: The driver closes a low voltage power supply switch and turns a key switch to the ON gear, the vehicle is started up at low voltage, and the vehicle controller VCU, the battery management system BMS, the high voltage box PDU and the bidirectional DC converter DC / DC are woken up.

[0035] The woken up controllers are self-checked at low voltage, and if the self-checking is passed, the high voltage start-up process is entered.

[0036] The vehicle controller VCU determines that the mode selection switch is in the driving mode and confirms that all high-voltage preparation conditions have been met, and then sends a Ready signal to the instrument screen.

[0037] The high-voltage preparation conditions include: the key switch gear is in the START position, the emergency stop switch is off, the direction switch is in the neutral position, the parking brake is closed, the battery management system BMS does not have a high-voltage preparation fault, the DC / DC converter does not have a high-voltage preparation fault, the contactors in the high-voltage box PDU are all in the open state, and the charging gun is not connected.

[0038] The driver turns the key switch to the START position, and the vehicle controller VCU receives the start signal and sends a high-voltage instruction to the six groups of bidirectional DC / DC converters.

[0039] After receiving the instruction, the DC / DC converter sends a BMS high-voltage instruction to the corresponding battery management system BMS, which immediately closes the main negative contactor and sends a HV closed confirmation signal to the DC / DC converter.

[0040] After receiving the HV closed signal, the DC / DC converter first confirms whether the manual maintenance switch MSD is closed, and if not, sends a fault message to the vehicle controller VCU.

[0041] If it is closed, it detects whether there is a sticking fault in the main positive relay, and if there is a fault, it sends a fault message to the vehicle controller VCU; if there is no fault, it closes the main positive relay.

[0042] The DC / DC converter detects whether the pre-charge relay has a sticking fault, and if it has a fault, it sends a fault message to the vehicle controller VCU; if it does not have a fault, it closes the pre-charge relay.

[0043] The battery high-voltage bus voltage is monitored in real time, and when the voltage rises to 90% of the battery voltage, the DC / DC converter delays for 1 second and closes the main variable relay.

[0044] After the main variable relay is reliably closed, the pre-charge relay is opened, and the DC / DC converter is started to build voltage for the vehicle high-voltage bus.

[0045] The power-down process includes normal power-down and emergency power-down, as shown in FIG. 6, wherein the normal power-down process is as follows: Figure 4 The driver turns the key switch from the start position back to the ON gear, and the vehicle controller VCU detects this state change and triggers the power-down process.

[0046] ​The vehicle controller VCU sends a shutdown signal to the frequency conversion control cabinet, closes the auxiliary equipment such as the traction frequency converter and the fan frequency converter, and stops the main power consumption.

[0047] The vehicle controller VCU sends a high-voltage-down command to all bidirectional DC / DC converters, and the DC / DC converter stops building voltage on the high-voltage bus of the vehicle after receiving the command.

[0048] The DC / DC converter continuously monitors the battery loop current, and after the current drops to a safe threshold (such as 5A), the main variable relay and the main positive relay are disconnected in turn.

[0049] The DC / DC converter then sends a high-voltage-down command to the battery management system BMS, and the battery management system BMS disconnects the main negative relay and feeds back an HV open signal to the DC / DC converter after receiving the command.

[0050] The frequency conversion control cabinet drives the brake resistance box to work, and the high-voltage bus of the vehicle and the high-voltage bus of the power battery are actively discharged.

[0051] As shown in Figure 4 the emergency power-down process is as follows: When the emergency stop switch is triggered or a high-voltage-down fault is detected in the DC / DC converter or the battery management system BMS, emergency power-down is started immediately.

[0052] The DC / DC converter stops, and the vehicle controller VCU sends an emergency stop signal to the frequency conversion control cabinet to stop the auxiliary equipment.

[0053] The DC / DC converter then disconnects the main variable relay and the main positive relay.

[0054] The high-voltage-down command is sent to the battery management system BMS, and the frequency conversion control cabinet drives the brake resistance box to work, and the high-voltage bus of the vehicle and the high-voltage bus of the battery are actively discharged.

[0055] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and embodiments having the same technical idea and playing the same role and effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications of the embodiments that can be thought of by those skilled in the art, and other ways constructed by combining part of the components of the embodiments are also included in the scope of the present application.

Claims

1. A power control device for a large-tonnage pure electric mining truck, characterized in that, include: The vehicle controller is used for energy management of the power battery, vehicle power-on / off and charging control; The battery management system is used to monitor the voltage, current, and temperature of the power battery in real time, perform fault diagnosis and protection of the power battery, and control the negative terminal of the high-voltage circuit of the battery. High-voltage box, used for relay control, adhesion detection and insulation detection of battery high-voltage bus circuit; The frequency converter control cabinet is used to control the operation of the vehicle's fan, traction frequency converter, and braking resistor box. The vehicle controller and the frequency converter control cabinet communicate via the vehicle CAN bus, the battery management system and the high-voltage box communicate via the battery CAN bus, and the frequency converter control cabinet and the battery management system are connected via the high-voltage bus.

2. The power control device for a large-tonnage pure electric mining truck as described in claim 1, characterized in that, The battery management system is also connected to a battery heating system and a battery cooling system via the battery CAN bus, which are used to heat and keep the power battery warm or cool it down based on the temperature detected by the battery management system.

3. The power control device for a large-tonnage pure electric mining truck as described in claim 1, characterized in that, The device further includes: Emergency stop switch is used to perform an emergency stop of the vehicle under high voltage in case of an emergency. The mode selection switch is used to select the vehicle's power-on mode, which is divided into driving mode power-on and insulation mode power-on. Both the emergency stop switch and the mode selection switch are connected to the vehicle controller via hard wiring.

4. The power control device for a large-tonnage pure electric mining truck as described in claim 1, characterized in that, The frequency converter control cabinet integrates a traction frequency converter, a braking resistor chopper unit, a fan frequency converter, and a charger, which are used to control the traction motor, the braking resistor box, the vehicle fan, and to achieve low-voltage charging, respectively.

5. The power control device for a large-tonnage pure electric mining truck as described in claim 4, characterized in that, The frequency converter control cabinet also integrates a DC-DC converter, which is used for voltage conversion between the battery high-voltage circuit and the vehicle high-voltage circuit, as well as data forwarding between the battery CAN bus and the vehicle CAN bus; the DC-DC converter is connected to the battery management system and the traction frequency converter respectively through a high-voltage wiring harness.

6. The power control device for a large-tonnage pure electric mining truck as described in claim 1, characterized in that, The relays include a main positive relay, a main negative relay, and a precharge relay.

7. A method for controlling the power supply and de-energization of a large-tonnage pure electric mining truck, characterized in that, Includes power-on and power-off procedures; The power-on process specifically includes: The driver closes the low-voltage power switch and turns the key switch to the ON position to wake up the vehicle controller, battery management system, high-voltage box and DC-DC converter. Each controller performs a low-voltage self-test; once it passes, it proceeds to the high-voltage process. The vehicle controller determines that the mode selection switch is in driving mode and sends a Ready signal after determining that the high voltage condition is met. When the key switch is turned to the START position, the vehicle controller sends a high-voltage command to the DC-DC converter. The DC-DC converter sends a high-voltage command to the battery management system, which closes the main negative contactor and sends back the HVclosed signal. After the manual maintenance switch MSD of the DC converter is closed and the main positive relay is not stuck, close the main positive relay. The DC-DC converter closes the pre-charge relay after detecting that it is not stuck. When the voltage of the high-voltage bus of the battery is detected to reach a preset ratio of the battery voltage, the main transformer relay is closed after a delay. Disconnect the precharge relay, start the DC converter, and build up voltage for the vehicle's high-voltage bus; After the pressure build-up is successful, the vehicle controller wakes up the frequency converter control cabinet and starts the auxiliary equipment; The power-down process specifically includes: When the key switch is returned to the ON position, the vehicle controller enters the power-down process. The vehicle controller sends a shutdown signal to the frequency converter control cabinet, and the auxiliary equipment stops. The vehicle controller sends a high-voltage command to the DC-DC converter. The DC converter stops, the high voltage bus of the whole vehicle stops building up voltage, and the main transformer relay is disconnected after the battery current is determined to be less than the preset threshold. After a delay, the high voltage command is sent to the battery management system. The battery management system disconnects the main negative relay and sends an HV open signal back to the DC-DC converter. The frequency converter control cabinet drives the braking resistor box to work, enabling the high-voltage busbar of the whole vehicle and the high-voltage busbar of the battery to actively discharge.

8. The power control method for a large-tonnage pure electric mining truck as described in claim 7, characterized in that, The power-down procedure also includes an emergency power-down procedure: When the emergency stop switch is triggered or a high-voltage fault is detected, the DC converter stops, the vehicle controller sends a stop signal to the frequency converter control cabinet, and the auxiliary equipment stops. The DC-DC converter disconnects the main transformer relay and the main positive relay; A high-voltage command is sent to the battery management system, and the frequency converter control cabinet drives the braking resistor box to work, so that the high-voltage bus of the whole vehicle and the high-voltage bus of the battery actively discharge.

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