A pure electric motor coach motor braking system and a control method, device and medium thereof

Abstract

The application provides a pure electric bus motor braking system and a control method, device and medium thereof, and relates to the technical field of electric vehicles.The pure electric bus motor braking system comprises a power battery, the power battery provides high voltage for a motor controller, a battery heater PTC, a battery water cooling unit and electric accessories through a high-voltage distribution unit; and a vehicle control unit VCU controls the communication of the whole vehicle.The application acquires the signals of the whole vehicle in real time, judges whether the long downhill opening condition is met, controls the opening of the battery heater PTC and the battery water cooling unit to work if the condition is met, and takes the braking torque corresponding to the maximum current of the motor system as the limit, executes the braking energy recovery of the motor system on the premise that the battery current is less than the maximum allowed charging current, and calculates the required braking torque instruction and sends it to the motor controller for execution.The application does not need to additionally increase the braking resistor, and the original battery heater PTC and water cooling unit are used to maximize the energy recovery and meet the electric braking requirement.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle technology, and more specifically, to a pure electric bus motor braking system and its control method, device, and medium. Background Technology

[0002] Pure electric buses, especially intercity pure electric tourist buses, frequently encounter long downhill driving conditions during operation, requiring a continuous braking system, including both electric and mechanical braking, to control the vehicle speed. However, when the power battery's charge is sufficient to prevent current recovery or when the allowed current recovery limit is very low, the electric braking will be unable to provide auxiliary braking. The vehicle's braking then relies primarily on mechanical braking. This can easily lead to prolonged and continuous use of mechanical braking when descending long slopes, causing brake pad wear or overheating and failure, thus creating safety hazards.

[0003] The existing technology mainly involves adding a high-power braking resistor to the original vehicle configuration. When driving downhill on a fully charged vehicle, the power is consumed by controlling the operation of the braking resistor, thereby absorbing the energy recovered by electric braking. However, the above solution has the following disadvantages: (1) The braking resistor has a large power and large size, and is generally air-cooled, resulting in a low level of safety protection; (2) The braking resistor needs to be installed in a ventilated position, usually on the roof of the vehicle. However, in the icy and snowy weather conditions in the north, the vehicle is often unable to drive due to insulation failure caused by snow accumulation, which greatly troubles the normal and safe operation of the vehicle; (3) The cost is high, and the vehicle product does not have a price advantage; (4) Once the braking resistor fails, there is no warning in advance before the mechanical brake fails due to overheating, which poses a safety hazard; (5) When the power battery is fully charged and driving downhill on a long slope, energy recovery cannot be maximized.

[0004] In view of this, the applicant hereby submits this application after studying the existing technology. Summary of the Invention

[0005] The present invention aims to provide a pure electric bus motor braking system and its control method, device and medium to solve the above problems.

[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0007] A braking system for a pure electric bus motor, comprising:

[0008] The power battery supplies high voltage to the motor controller, battery heater PTC, battery water-cooled unit, and electrical accessories via a high-voltage power distribution unit.

[0009] The vehicle controller (VCU) is electrically connected to the power battery, the high-voltage power distribution unit, the motor controller, the battery heater (PTC), and the battery water cooling unit, and controls vehicle communication through the vehicle controller (VCU).

[0010] The vehicle control unit (VCU) also includes a processor and a memory, wherein the processor is used to run computer programs stored in the memory to achieve:

[0011] S1, real-time acquisition of vehicle signals, including: throttle signal, brake signal, retarder lever signal, temperature sensor signal, instrument indicator signal, SOC value of power battery, allowable charging current value of battery, battery temperature and vehicle speed signal.

[0012] S2, determine whether the downhill start condition is met based on the vehicle signal; when the downhill start condition is met, the vehicle controller (VCU) controls the battery heater (PTC) and the battery water-cooling unit to start working; otherwise, the vehicle controller (VCU) controls the battery heater (PTC) and the battery water-cooling unit to stop working; wherein, the expression for the downhill start condition is:

[0013] The SOC value ≥ 95 is applied to the vehicle control unit (VCU), and the battery's allowable charging current is < 80A, the battery temperature is < 45℃, the deceleration lever is open, the vehicle speed is > 15 km / h, and the throttle opening is < 5%.

[0014] S3, when the battery heater PTC and the battery water-cooling unit are working, determine whether the long downhill shutdown condition is met based on the vehicle signal; when the long downhill shutdown condition is met, the vehicle controller VCU controls the battery heater PTC and the battery water-cooling unit to shut down; otherwise, the vehicle controller VCU controls the battery heater PTC and the battery water-cooling unit to start working.

[0015] The expression for the closure condition of the long downhill slope is as follows:

[0016] SOC value ≤ 90 or battery allowable charging current > 150A or battery temperature > 50℃ or deceleration lever closed or vehicle speed < 10 mph or throttle opening > 10% or throttle opening for more than 10 seconds;

[0017] S4, when the battery heater PTC and the battery water-cooling unit are working, the vehicle controller VCU uses the current maximum return current I of the motor system. SyaMaxChgThe corresponding braking torque is limited, and under the premise that the battery charging current is less than the maximum allowable charging current of the battery, the braking energy recovery of the motor system is performed, the required braking torque command is calculated, and the braking torque command is sent to the motor controller for execution.

[0018] Preferably, the current maximum return current I of the motor system SyaMaxChg The formula is:

[0019] I SyaMaxChg =I BatMaxchgat +I Bat -I MCU

[0020] Among them, I BatMaxchgat Indicates the maximum allowable charging current of the power battery; I Bat This represents the real-time battery current transmitted by the power battery. The battery current value is positive or negative; it is positive when the battery is driving discharge and negative when it is braking and regenerating. MCU This represents the DC current of the motor bus sent in real time by the motor controller. The value is positive or negative; it is positive during drive discharge and negative during braking recirculation. Bat -I MCU This indicates the current of power-consuming equipment other than the drive motor, including the battery heater PTC, the battery water-cooling unit, and electrical accessories.

[0021] Preferably, the regenerative braking energy recovery of the motor system specifically includes:

[0022] The brake pedal opening is determined based on the acquired brake signal. If the brake pedal opening b>0, the battery current is determined based on the acquired power battery current signal; otherwise, the throttle opening a is determined based on the acquired throttle signal.

[0023] When the battery current I Bat When <0, determine the absolute value of the battery current |I Bat Is it less than the battery's maximum allowable charging current I? BatMaxchgat Otherwise, the vehicle control unit (VCU) calculates the required braking torque T.

[0024] When the absolute value of the battery current |I Bat | Less than the maximum allowable charging current of the battery I BatMaxchga When the braking torque T is required, the vehicle control unit (VCU) calculates the required braking torque T; otherwise, the braking torque T is 0.

[0025] When the throttle opening a>0, it is determined whether the current vehicle speed exceeds the threshold. If it does not exceed the threshold, the drive torque is output; if it does exceed the threshold, the speed limit mode is entered. Otherwise, the retarder lever position is determined based on the acquired retarder lever signal.

[0026] When the slow speed lever is in the 0 position, the current vehicle speed is obtained to determine whether it exceeds the threshold. If it does not exceed the threshold, the vehicle enters the free coasting mode; if it does exceed the threshold, the vehicle enters the speed limit mode. Otherwise, the battery current is determined based on the obtained power battery current signal.

[0027] Preferably, the method further includes obtaining the brake temperature of the wheels by reading the temperature sensor signals installed at the brake ends of the front and rear wheels through the vehicle controller (VCU).

[0028] Preferably, the temperature sensor is a PT100 type.

[0029] Preferably, it further includes: comparing the brake temperature of the wheel with a set temperature alarm threshold in real time, and executing a braking performance warning mode, wherein the braking performance warning mode specifically includes:

[0030] When the brake temperature of any wheel is greater than or equal to the first temperature threshold T1, the red light on the instrument panel of the vehicle controller (VCU) will sound an alarm to remind the driver to stop.

[0031] When the brake temperature of any wheel is greater than or equal to the second temperature threshold T2, a yellow warning light will be displayed on the instrument panel of the vehicle control unit (VCU).

[0032] This invention also provides a method for controlling the braking of a pure electric bus motor, applied to the vehicle controller (VCU), comprising the following steps:

[0033] S1, real-time acquisition of vehicle signals, including: throttle signal, brake signal, retarder lever signal, temperature sensor signal, instrument indicator signal, SOC value of power battery, allowable charging current value of battery, battery temperature and vehicle speed signal.

[0034] S2, determine whether the downhill start condition is met based on the vehicle signal; when the downhill start condition is met, control the battery heater PTC and battery water cooling unit to start working; otherwise, control the battery heater PTC and battery water cooling unit to stop working; wherein, the expression for the downhill start condition is:

[0035] SOC value ≥ 95% and battery allowable charging current < 80A and battery temperature < 45℃, with slow handle on, vehicle speed > 15 km / h and throttle opening < 5%;

[0036] S3, when the battery heater PTC and the battery water cooling unit are working, determine whether the downhill shutdown condition is met based on the vehicle signal; if the downhill shutdown condition is met, control the battery heater PTC and the battery water cooling unit to be shut down; otherwise, control the battery heater PTC and the battery water cooling unit to be turned on.

[0037] The expression for the closure condition of the long downhill slope is as follows:

[0038] SOC value ≤ 90 or battery allowable charging current > 150A or battery temperature > 50℃ or deceleration lever closed or vehicle speed < 10 mph or throttle opening > 10% or throttle opening for more than 10 seconds;

[0039] S4, When the battery heater PTC and the battery water-cooled unit are working, the current maximum return current I of the motor system is used. SyaMaxChg The corresponding braking torque is limited, and under the premise that the battery charging current is less than the maximum allowable charging current of the battery, the braking energy recovery of the motor system is performed, the required braking torque command is calculated, and the braking torque command is sent to the motor controller for execution.

[0040] Preferably, the current maximum return current I of the motor system SyaMaxChg The formula is:

[0041] I SyaMaxChg =I BatMaxchgat +I Bat -I MCU

[0042] Among them, I BatMaxchgat Indicates the maximum allowable charging current of the power battery; I Bat This represents the real-time battery current transmitted by the power battery. The battery current value is positive or negative; it is positive when the battery is driving discharge and negative when it is braking and regenerating. MCU This represents the DC current of the motor bus sent in real time by the motor controller. The value is positive or negative; it is positive during drive discharge and negative during braking recirculation. Bat -I MCU This indicates the current of power-consuming equipment other than the drive motor, including the battery heater PTC, the battery water-cooling unit, and electrical accessories.

[0043] The present invention also provides a braking control device for a pure electric bus motor, comprising:

[0044] The signal acquisition module is used to acquire vehicle signals in real time, including: throttle signal, brake signal, retarder lever signal, temperature sensor signal, instrument reading data, SOC value of the power battery, allowable charging current value of the battery, battery temperature, and vehicle speed signal.

[0045] The first judgment module is used to determine whether the downhill start condition is met based on the vehicle signal; when the downhill start condition is met, it controls the battery heater PTC and battery water cooling unit to start working; otherwise, it controls the battery heater PTC and battery water cooling unit to be turned off; wherein, the expression of the downhill start condition is:

[0046] SOC value ≥ 95% and battery allowable charging current < 80A and battery temperature < 45℃, with slow handle on, vehicle speed > 15 km / h and throttle opening < 5%;

[0047] The second judgment module is used to determine whether the downhill shutdown condition is met. When the battery heater PTC and the battery water cooling unit are working, the module determines whether the downhill shutdown condition is met based on the vehicle signal. If the downhill shutdown condition is met, the module controls the battery heater PTC and the battery water cooling unit to be shut down. Otherwise, the module controls the battery heater PTC and the battery water cooling unit to be turned on.

[0048] The expression for the closure condition of the long downhill slope is as follows:

[0049] SOC value ≤ 90 or battery allowable charging current > 150A or battery temperature > 50℃ or deceleration lever closed or vehicle speed < 10 mph or throttle opening > 10% or throttle opening for more than 10 seconds;

[0050] The braking energy recovery module is used to obtain the required braking torque command. When the battery heater PTC and the battery water-cooled unit are working, it uses the current maximum return current I of the motor system. SyaMaxChg The corresponding braking torque is limited, and under the premise that the battery charging current is less than the maximum allowable charging current of the battery, the braking energy recovery of the motor system is performed, the required braking torque command is calculated, and the braking torque command is sent to the motor controller for execution.

[0051] The present invention also provides a computer-readable storage medium, including computer-readable instructions stored on the computer-readable storage medium, wherein when the computer-readable instructions are executed by a processor of the device in which the computer-readable storage medium is located, the computer-readable instructions implement the control method for braking of a pure electric bus motor as described above.

[0052] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0053] (1) This invention does not require an additional braking resistor. By using the existing battery heater PTC and water cooling unit, when the power battery is fully charged and braking down a long slope, it controls the power consumption at the same time and can exert the maximum electric braking force to achieve continuous electric braking of electric vehicles down long slopes, thus solving the braking problem of pure electric buses when fully charged and going down long slopes.

[0054] (2) The energy recovery strategy of the present invention adopts the maximum recovery current of the motor system and adds the power consumption current of all power-consuming equipment to maximize energy recovery. It can realize electric braking under full charge conditions, thereby improving the comfort and safety of braking. It can also increase the power recovery of the power battery, thereby increasing the driving range.

[0055] (3) The present invention replaces the technical solution of adding an additional braking resistor, thus avoiding the safety, reliability and cost problems caused by the added braking resistor.

[0056] (4) The present invention adds temperature detection for four wheel brakes and sets up an early warning mechanism to prevent mechanical brake failure caused by excessive wheel temperature, which greatly improves the safety of the vehicle's braking system. Attached Figure Description

[0057] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0058] Figure 1 This is a schematic diagram of the structure of the electric motor braking system for a pure electric bus provided in the first embodiment of the present invention.

[0059] Figure 2 This is a flowchart illustrating the working logic of the battery heater PTC and battery water cooling unit provided in the first embodiment of the present invention.

[0060] Figure 3 This is a schematic diagram of the high-voltage current flow of the whole vehicle provided in the first embodiment of the present invention.

[0061] Figure 4 This is a schematic diagram of the electric braking energy recovery strategy provided in the first embodiment of the present invention.

[0062] Figure 5 This is a flowchart of the braking performance warning logic provided in the first embodiment of the present invention.

[0063] Figure 6 This is a flowchart illustrating the pure electric bus motor braking control method provided in the second embodiment of the present invention.

[0064] Figure 7 This is a schematic diagram of the structure of the pure electric bus motor braking control device provided in the third embodiment of the present invention.

[0065] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0066] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0067] Example 1

[0068] like Figure 1 As shown, this invention provides a pure electric bus motor braking system. The power battery provides high voltage to the motor controller, battery heater PTC, battery water-cooled unit, and electrical accessories through a high-voltage power distribution unit. The vehicle controller, as the core of the entire control system, is electrically connected to the power battery, the high-voltage power distribution unit, the motor controller, the battery heater PTC, and the battery water-cooled unit. The vehicle controller (VCU) controls vehicle communication and acquires vehicle signals in real time, such as driver operation signals (including throttle signals, brake signals, and deceleration lever signals), temperature sensor signals (brake temperatures of the four wheels), instrument indication signals, the SOC value of the power battery, the allowable charging current value of the battery, battery temperature, and vehicle speed signals.

[0069] The vehicle control unit (VCU) also includes a processor and a memory, wherein the processor is used to run computer programs stored in the memory to achieve, for example... Figure 2 The control logic flow shown is as follows:

[0070] S1, real-time acquisition of vehicle signals, wherein the vehicle signals include: temperature sensor signals, instrument indication signals, SOC value of power battery, allowable charging current value of battery, battery temperature and vehicle speed signal;

[0071] S2, determine whether the downhill start condition is met based on the vehicle signal; when the downhill start condition is met, the vehicle controller (VCU) controls the battery heater (PTC) and battery water-cooling unit to start working; otherwise, the vehicle controller (VCU) controls the battery heater (PTC) and battery water-cooling unit to shut down, and the power battery management system (BMS) controls the battery heater (PTC) and battery water-cooling unit according to actual needs; wherein, the expression for the downhill start condition is:

[0072] SOC value ≥ 95% and battery allowable charging current < 80A and battery temperature < 45℃, with slow handle on, vehicle speed > 15 km / h and throttle opening < 5%;

[0073] S3, when the battery heater PTC and the battery water-cooling unit are working, the system determines whether the downhill shutdown condition is met based on the vehicle signal; if the downhill shutdown condition is met, the vehicle controller VCU controls the battery heater PTC and the battery water-cooling unit to shut down, and the power battery BMS controls the battery heater PTC and the battery water-cooling unit according to actual needs; otherwise, the vehicle controller VCU controls the battery heater PTC and the battery water-cooling unit to start working.

[0074] The expression for the closure condition of the long downhill slope is as follows:

[0075] SOC value ≤ 90 or battery allowable charging current > 150A or battery temperature > 50℃ or deceleration lever closed or vehicle speed < 10 mph or throttle opening > 10% or throttle opening for more than 10 seconds;

[0076] S4, when the battery heater PTC and the battery water-cooling unit are working, the vehicle controller VCU uses the current maximum return current I of the motor system. SyaMaxChg The corresponding braking torque is limited, and under the premise that the battery charging current is less than the maximum allowable charging current of the battery, the braking energy recovery of the motor system is performed, the required braking torque command is calculated, and the braking torque command is sent to the motor controller for execution.

[0077] Specifically, in this embodiment, the vehicle control unit (VCU), the brain of the vehicle, controls the drive motor control system to perform driving and electric braking energy recovery according to the driver's operation instructions, so as to realize the normal driving of the vehicle.

[0078] Battery Management System (BMS): Primarily monitors information such as the voltage and temperature of individual cells within the power battery, and manages the charging and discharging current limits and temperature limits in real time to achieve safe monitoring of the power battery.

[0079] Electric braking: relies on the electric braking force generated by the braking torque (or energy recovery) of the drive motor.

[0080] Mechanical braking: relies on the vehicle's traditional mechanical braking, which is generally air braking, and the friction generated by the brake disc.

[0081] Electrical accessories: High-voltage electrical accessory devices, including electric air compressors, electric steering, DC-DC converters, electric air conditioners, electric heaters, etc.

[0082] Specifically, as shown in Figure 3, the current flow of the vehicle's high voltage is used to determine the maximum rechargeable current I of the current motor system. SyaMaxChg I SyaMaxChg It consists of two parts: one part is based on the maximum allowable charging current I of the power battery. BatMaxchgat To limit the charging of the power battery, another portion of the current (I) flows through power-consuming devices other than the drive motor (including the electric heater PTC, water-cooled unit, and electrical accessories). consume Consumed.

[0083] Among them I BatMaxchgat The absolute value of the current I of the power battery BMS is obtained in real time and transmitted (considering that some BMS transmit this value as a negative value). consume =I Bat -I MCU , where I Bat This refers to the battery current (which is positive and negative; positive during drive discharge and negative during braking recharge, and is transmitted in real time by the BMS), I. MCU This is the DC current of the motor bus (it is positive and negative; it is positive during drive discharge and negative during braking recirculation, and is sent in real time by the motor controller MCU).

[0084] In summary, the maximum recirculation current I of the current motor system can be determined. SyaMaxChg =I BatMaxchgat +(I Bat -I MCU ).

[0085] When operating on a long slope at full charge, with both the electric heater (PTC) and the battery water-cooled unit starting simultaneously, I consume The value will increase accordingly, adding to the power consumption current of the electric heater PTC and battery water-cooling unit, thereby increasing the maximum return current I of the current motor system. SyaMaxChg .

[0086] Under braking conditions, the vehicle controller operates at the current maximum return current I of the motor system. SyaMaxChg The corresponding braking torque is limited, and the battery charging current is guaranteed (in the case of braking and when the battery current is negative, this value is the current battery current I). BatProvided that the absolute value of the braking torque is less than the maximum allowable charging current of the battery, the required braking torque command is calculated and sent to the motor controller for execution, thereby realizing the braking energy recovery of the motor system.

[0087] Specific electric braking energy recovery strategies, such as Figure 4 As shown.

[0088] The brake pedal opening is determined based on the acquired brake signal. If the brake pedal opening b>0, the battery current is determined based on the acquired power battery current signal; otherwise, the throttle opening a is determined based on the acquired throttle signal.

[0089] When the battery current I Bat When <0, determine the absolute value of the battery current |I Bat Is it less than the battery's maximum allowable charging current I? BatMaxchgat Otherwise, the vehicle control unit (VCU) calculates the required braking torque T based on the brake pedal opening (or EBS request) and parameters such as motor speed and vehicle speed. The maximum value cannot exceed the braking torque corresponding to Isyamaxchg.

[0090] When the absolute value of the battery current |I Bat | Less than the battery's maximum allowable charging current I BatMaxchga At that time, the vehicle control unit (VCU) calculates the required braking torque T based on the brake pedal opening (or EBS request) and parameters such as motor speed and vehicle speed. The maximum value cannot exceed the braking torque corresponding to Isyamaxchg; otherwise, the braking torque T is 0.

[0091] When the throttle opening a>0, it is determined whether the current vehicle speed exceeds the threshold. If it does not exceed the threshold, the drive torque is output; if it does exceed the threshold, the speed limit mode is entered. Otherwise, the retarder lever position is determined based on the acquired retarder lever signal.

[0092] When the slow speed lever is in the 0 position, the current vehicle speed is obtained to determine whether it exceeds the threshold. If it does not exceed the threshold, the vehicle enters the free coasting mode; if it does exceed the threshold, the vehicle enters the speed limit mode. Otherwise, the battery current is determined based on the obtained power battery current signal.

[0093] When the battery current I Bat When <0, determine the absolute value of the battery current |I Bat Is it less than the battery's maximum allowable charging current I? BatMaxchgat Otherwise, the vehicle controller (VCU) calculates the required braking torque T based on the different gear signals of the deceleration lever, combined with parameters such as motor speed and vehicle speed. The maximum value cannot exceed the braking torque corresponding to Isyamaxchg.

[0094] When the absolute value of the battery current |I Bat| Less than the battery's maximum allowable charging current I BatMaxchga At that time, the vehicle controller (VCU) calculates the required braking torque T based on the different gear signals of the deceleration lever, combined with parameters such as motor speed and vehicle speed. The maximum value cannot exceed the braking torque corresponding to Isyamaxchg; otherwise, the braking torque T is 0.

[0095] Specifically, during braking on a long downhill slope, when greater braking force is required (at which point the brake pedal is pressed deeper), in addition to electric braking, mechanical braking also intervenes.

[0096] When mechanical braking is continuously engaged, disc brakes convert the vehicle's kinetic and potential energy into heat energy through the friction of the brake disc and pads. The vehicle's braking performance, that is, the braking energy that the brakes can withstand, is directly related to the brake temperature. When the brake temperature reaches a certain threshold, the mechanical braking performance will decrease.

[0097] Based on this principle, the present invention adds PT100 type temperature sensors to the brake ends of the front and rear wheels. The sensor signals are read and detected by the AD sampling port of the VCU and compared with the set temperature alarm threshold in real time. When the alarm threshold is exceeded, the driver is alerted by displaying an alarm on the instrument panel.

[0098] The specific alarm logic of the braking performance warning system is as follows: Figure 5 As shown.

[0099] When the brake temperature of any wheel is greater than or equal to the first temperature threshold T1, the red light on the instrument panel of the vehicle controller (VCU) will sound an alarm to remind the driver to stop.

[0100] When the brake temperature of any wheel is greater than or equal to the second temperature threshold T2, a yellow warning light will appear on the instrument panel of the vehicle control unit (VCU).

[0101] Otherwise, the overall vehicle braking strength is considered normal.

[0102] The battery heater (PTC) and battery water-cooling unit serve as the thermal management system for the power battery. Under normal operating conditions, they can heat the power battery according to the requirements of the battery management system (BMS) (the PTC operates as requested by the BMS when the power battery is at a low temperature) or cool the power battery (the water-cooling unit operates as requested by the BMS when the power battery is at a high temperature). When the power battery is fully charged and meets the requirements for long downhill braking, the VCU controls the PTC and water-cooling unit to operate simultaneously to consume power. Based on the battery's allowable charging current and the power consumption current of the vehicle's electrical equipment, it calculates the maximum current that the motor system can recover, thereby maximizing the control of the drive motor for electric braking. Simultaneously, the VCU monitors the brake end temperature of all four wheels and issues an early warning on the instrument panel when the alarm threshold is reached.

[0103] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0104] (1) This invention does not require an additional braking resistor. By using the existing battery heater PTC and water cooling unit, when the power battery is fully charged and braking down a long slope, it controls the power consumption at the same time and can exert the maximum electric braking force to achieve continuous electric braking of electric vehicles down long slopes, thus solving the braking problem of pure electric buses when fully charged and going down long slopes.

[0105] (2) The energy recovery strategy of the present invention adopts the maximum recovery current of the motor system and adds the power consumption current of all power-consuming equipment to maximize energy recovery. It can realize electric braking under full charge conditions, thereby improving the comfort and safety of braking. It can also increase the power recovery of the power battery, thereby increasing the driving range.

[0106] (3) The present invention replaces the technical solution of adding an additional braking resistor, thus avoiding the safety, reliability and cost problems caused by the added braking resistor.

[0107] (4) The present invention adds temperature detection for four wheel brakes and sets up an early warning mechanism to prevent mechanical brake failure caused by excessive wheel temperature, which greatly improves the safety of the vehicle's braking system.

[0108] Example 2

[0109] like Figure 6 As shown, this embodiment of the invention provides a method for controlling the braking of a pure electric bus motor, applied to the vehicle controller (VCU), and its steps include:

[0110] S1, real-time acquisition of vehicle signals, including: throttle signal, brake signal, retarder lever signal, temperature sensor signal, instrument indicator signal, SOC value of power battery, allowable charging current value of battery, battery temperature and vehicle speed signal.

[0111] S2, determine whether the downhill start condition is met based on the vehicle signal; when the downhill start condition is met, control the battery heater PTC and battery water cooling unit to start working; otherwise, control the battery heater PTC and battery water cooling unit to stop working; wherein, the expression for the downhill start condition is:

[0112] SOC value ≥ 95% and battery allowable charging current < 80A and battery temperature < 45℃, with slow handle on, vehicle speed > 15 km / h and throttle opening < 5%;

[0113] S3, when the battery heater PTC and the battery water cooling unit are working, determine whether the downhill shutdown condition is met based on the vehicle signal; if the downhill shutdown condition is met, control the battery heater PTC and the battery water cooling unit to be shut down; otherwise, control the battery heater PTC and the battery water cooling unit to be turned on.

[0114] The expression for the closure condition of the long downhill slope is as follows:

[0115] SOC value ≤ 90 or battery allowable charging current > 150A or battery temperature > 50℃ or deceleration lever closed or vehicle speed < 10 mph or throttle opening > 10% or throttle opening for more than 10 seconds;

[0116] S4, When the battery heater PTC and the battery water-cooled unit are working, the current maximum return current I of the motor system is used. SyaMaxChg The corresponding braking torque is limited, and under the premise that the battery charging current is less than the maximum allowable charging current of the battery, the braking energy recovery of the motor system is performed, the required braking torque command is calculated, and the braking torque command is sent to the motor controller for execution.

[0117] Specifically, the current maximum return current I of the motor system SyaMaxChg The formula is:

[0118] I SyaMaxChg =I BatMaxchgat +I Bat -I MCU

[0119] Among them, I BatMaxchgat Indicates the maximum allowable charging current of the power battery; I Bat This represents the real-time battery current transmitted by the power battery. The battery current value is positive or negative; it is positive when the battery is driving discharge and negative when it is braking and regenerating. MCU This represents the DC current of the motor bus sent in real time by the motor controller. The value is positive or negative; it is positive during drive discharge and negative during braking recirculation. Bat -I MCU This indicates the current of power-consuming equipment other than the drive motor, including the battery heater PTC, the battery water-cooling unit, and electrical accessories.

[0120] Example 3

[0121] like Figure 7 As shown, an embodiment of the present invention provides a braking control device for a pure electric bus motor, which includes:

[0122] The signal acquisition module is used to acquire vehicle signals in real time, including: throttle signal, brake signal, retarder lever signal, temperature sensor signal, instrument reading data, SOC value of the power battery, allowable charging current value of the battery, battery temperature, and vehicle speed signal.

[0123] The first judgment module is used to determine whether the downhill start condition is met based on the vehicle signal; when the downhill start condition is met, it controls the battery heater PTC and battery water cooling unit to start working; otherwise, it controls the battery heater PTC and battery water cooling unit to be turned off; wherein, the expression of the downhill start condition is:

[0124] SOC value ≥ 95% and battery allowable charging current < 80A and battery temperature < 45℃, with slow handle on, vehicle speed > 15 km / h and throttle opening < 5%;

[0125] The second judgment module is used to determine whether the downhill shutdown condition is met. When the battery heater PTC and the battery water cooling unit are working, the module determines whether the downhill shutdown condition is met based on the vehicle signal. If the downhill shutdown condition is met, the module controls the battery heater PTC and the battery water cooling unit to be shut down. Otherwise, the module controls the battery heater PTC and the battery water cooling unit to be turned on.

[0126] The expression for the closure condition of the long downhill slope is as follows:

[0127] SOC value ≤ 90 or battery allowable charging current > 150A or battery temperature > 50℃ or deceleration lever closed or vehicle speed < 10 mph or throttle opening > 10% or throttle opening for more than 10 seconds;

[0128] The braking energy recovery module is used to obtain the required braking torque command. When the battery heater PTC and the battery water-cooled unit are working, it uses the current maximum return current I of the motor system. SyaMaxChg The corresponding braking torque is limited, and under the premise that the battery charging current is less than the maximum allowable charging current of the battery, the braking energy recovery of the motor system is performed, the required braking torque command is calculated, and the braking torque command is sent to the motor controller for execution.

[0129] Example 4

[0130] The fourth embodiment of the present invention also provides a computer-readable storage medium, which includes computer-readable instructions stored on the computer-readable storage medium. When the computer-readable instructions are executed by the processor of the device where the computer-readable storage medium is located, they implement the above-described method for controlling the braking of a pure electric bus motor.

[0131] In the several embodiments provided in this invention, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus and method embodiments described above are merely illustrative. For example, the flowcharts in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of the invention. In this regard, each block in the flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and combinations of blocks in the block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0132] In addition, the functional modules in the various embodiments of the present invention can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0133] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, electronic device, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks. It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. In the absence of further restrictions, an element defined by the phrase "comprising a..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0134] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0135] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0136] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0137] The use of "first" and "second" in the embodiments is merely to distinguish similar objects and does not represent a specific ordering of objects. It is understood that "first" and "second" can be interchanged in a specific order or sequence where permitted. It should be understood that the objects distinguished by "first" and "second" can be interchanged where appropriate so that the embodiments described herein can be implemented in an order other than those illustrated or described herein.

[0138] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A braking system for a pure electric bus motor, characterized in that, include: The power battery supplies high voltage to the motor controller, battery heater PTC, battery water-cooled unit, and electrical accessories via a high-voltage power distribution unit. The vehicle controller (VCU) is electrically connected to the power battery, the high-voltage power distribution unit, the motor controller, the battery heater (PTC), and the battery water cooling unit, and controls vehicle communication through the vehicle controller (VCU). The vehicle control unit (VCU) also includes a processor and a memory, wherein the processor is used to run computer programs stored in the memory to achieve: S1, real-time acquisition of vehicle signals, including: throttle signal, brake signal, retarder lever signal, temperature sensor signal, instrument indicator signal, SOC value of power battery, allowable charging current value of battery, battery temperature and vehicle speed signal. S2, determine whether the downhill start condition is met based on the vehicle signal; when the downhill start condition is met, the vehicle controller (VCU) controls the battery heater (PTC) and the battery water-cooling unit to start working; otherwise, the vehicle controller (VCU) controls the battery heater (PTC) and the battery water-cooling unit to stop working; wherein, the expression for the downhill start condition is: ； S3, when the battery heater PTC and the battery water-cooling unit are working, determine whether the long downhill shutdown condition is met based on the vehicle signal; when the long downhill shutdown condition is met, the vehicle controller VCU controls the battery heater PTC and the battery water-cooling unit to shut down; otherwise, the vehicle controller VCU controls the battery heater PTC and the battery water-cooling unit to start working. The expression for the closure condition of the long downhill slope is as follows: ； S4, When the battery heater PTC and the battery water-cooling unit are working, the vehicle controller VCU uses the current maximum return current of the motor system. The corresponding braking torque is limited, and under the premise that the battery charging current is less than the maximum allowable charging current of the battery, the regenerative braking of the motor system is executed, the required braking torque command is calculated, and the braking torque command is sent to the motor controller for execution; wherein, the current maximum regenerative braking current of the motor system is... The formula is: ; in, This indicates the maximum allowable charging current of the power battery; It represents the battery current sent by the power battery in real time. The battery current value is positive and negative. It is positive when the battery is driving discharge and negative when braking and recharging. This represents the DC current of the motor bus sent in real time by the motor controller. The value is positive or negative, being positive during drive discharge and negative during braking recirculation. This indicates the current of power-consuming equipment other than the drive motor, including the battery heater PTC, the battery water-cooling unit, and electrical accessories.

2. The electric motor braking system for a pure electric bus according to claim 1, characterized in that, The regenerative braking energy recovery of the motor system specifically includes: The brake pedal opening is determined based on the acquired brake signal. If the brake pedal opening is... If the battery current is not determined by the acquired power battery current signal, then the throttle opening is determined by the acquired throttle signal. ; When battery current At that time, determine the absolute value of the battery current. Is it less than the battery's maximum allowable charging current? Otherwise, the vehicle control unit (VCU) calculates the required braking torque. ; When the absolute value of the battery current Less than the battery's maximum allowable charging current At that time, the vehicle control unit (VCU) calculates the required braking torque. Otherwise, braking torque =0; When the throttle opening When the current vehicle speed exceeds the threshold, the system determines whether the current speed exceeds the threshold. If it does not exceed the threshold, the system outputs the drive torque. If it does exceed the threshold, the system enters the speed limit mode. Otherwise, the system determines whether the speed limit lever is at 0 based on the acquired speed limit lever signal. When the slow speed lever is in the 0 position, the current vehicle speed is obtained to determine whether it exceeds the threshold. If it does not exceed the threshold, the vehicle enters the free coasting mode; if it does exceed the threshold, the vehicle enters the speed limit mode. Otherwise, the battery current is determined based on the obtained power battery current signal.

3. The electric motor braking system for a pure electric bus according to claim 1, characterized in that, It also includes obtaining the brake temperature of the wheels by reading the temperature sensor signals installed at the brake ends of the front and rear wheels through the vehicle controller (VCU).

4. The electric motor braking system for a pure electric bus according to claim 3, characterized in that, The temperature sensor is a PT100 type.

5. The electric motor braking system for a pure electric bus according to claim 4, characterized in that, Also includes: Based on the brake temperature of the wheel, a real-time comparison is made with the set temperature alarm threshold to execute a braking performance warning mode. Specifically, the braking performance warning mode includes: When the brake temperature of any wheel is greater than or equal to the first temperature threshold T1, the red light on the instrument panel of the vehicle controller (VCU) will sound an alarm to remind the driver to stop. When the brake temperature of any wheel is greater than or equal to the second temperature threshold T2, a yellow warning light will be displayed on the instrument panel of the vehicle control unit (VCU).

6. A method for controlling the braking of a pure electric bus motor, applied to the vehicle control unit (VCU), characterized in that, Includes the following steps: S1, real-time acquisition of vehicle signals, including: throttle signal, brake signal, retarder lever signal, temperature sensor signal, instrument indicator signal, SOC value of power battery, allowable charging current value of battery, battery temperature and vehicle speed signal. S2, determine whether the downhill start condition is met based on the vehicle signal; when the downhill start condition is met, control the battery heater PTC and battery water cooling unit to start working; otherwise, control the battery heater PTC and battery water cooling unit to stop working; wherein, the expression for the downhill start condition is: ； S3, when the battery heater PTC and the battery water cooling unit are working, determine whether the downhill shutdown condition is met based on the vehicle signal; if the downhill shutdown condition is met, control the battery heater PTC and the battery water cooling unit to be shut down; otherwise, control the battery heater PTC and the battery water cooling unit to be turned on. The expression for the closure condition of the long downhill slope is as follows: ； S4, When the battery heater PTC and the battery water-cooled unit are working, the maximum return current of the current motor system is used. The corresponding braking torque is limited, and under the premise that the battery charging current is less than the maximum allowable charging current of the battery, the braking energy recovery of the motor system is executed, the required braking torque command is calculated, and the braking torque command is sent to the motor controller for execution; Among them, the current maximum return current of the motor system The formula is: ; in, This indicates the maximum allowable charging current of the power battery; It represents the battery current sent by the power battery in real time. The battery current value is positive and negative. It is positive when the battery is driving discharge and negative when braking and recharging. This represents the DC current of the motor bus sent in real time by the motor controller. The value is positive or negative, being positive during drive discharge and negative during braking recirculation. This indicates the current of power-consuming equipment other than the drive motor, including the battery heater PTC, the battery water-cooling unit, and electrical accessories.

7. A braking control device for a pure electric bus motor, characterized in that, include: The signal acquisition module is used to acquire vehicle signals in real time, including: throttle signal, brake signal, retarder lever signal, temperature sensor signal, instrument reading data, SOC value of the power battery, allowable charging current value of the battery, battery temperature, and vehicle speed signal. The first judgment module is used to determine whether the downhill start condition is met based on the vehicle signal; when the downhill start condition is met, it controls the battery heater PTC and battery water cooling unit to start working; otherwise, it controls the battery heater PTC and battery water cooling unit to be turned off; wherein, the expression of the downhill start condition is: ； The second judgment module is used to determine whether the downhill shutdown condition is met. When the battery heater PTC and the battery water cooling unit are working, the module determines whether the downhill shutdown condition is met based on the vehicle signal. If the downhill shutdown condition is met, the module controls the battery heater PTC and the battery water cooling unit to be shut down. Otherwise, the module controls the battery heater PTC and the battery water cooling unit to be turned on. The expression for the closure condition of the long downhill slope is as follows: ； The braking energy recovery module is used to obtain the required braking torque command. When the battery heater PTC and the battery water-cooled unit are working, it uses the current maximum return current of the motor system. The corresponding braking torque is limited, and under the premise that the battery charging current is less than the maximum allowable charging current of the battery, the braking energy recovery of the motor system is executed, the required braking torque command is calculated, and the braking torque command is sent to the motor controller for execution; Among them, the current maximum return current of the motor system The formula is: ; in, This indicates the maximum allowable charging current of the power battery; It represents the battery current sent by the power battery in real time. The battery current value is positive and negative. It is positive when the battery is driving discharge and negative when braking and recharging. This represents the DC current of the motor bus sent in real time by the motor controller. The value is positive or negative, being positive during drive discharge and negative during braking recirculation. This indicates the current of power-consuming equipment other than the drive motor, including the battery heater PTC, the battery water-cooling unit, and electrical accessories.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-readable instructions, which, when executed by the processor of the device on which the computer-readable storage medium resides, implement the electric motor braking control method for a pure electric bus as described in claim 6.

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