A 48V mild hybrid system and its control method

Abstract

The present application relates to a 48V mild hybrid system and its control method, which includes: a 48V electrical system, which includes a 48V motor, a 48V electric heating device, and a 48V air conditioner connected to a 48V pseudocapacitor; a 24V electrical system, which includes a 24V lead-acid battery and a vehicle-wide 24V electrical load connected to each other; a DC / DC converter, which connects the 48V electrical system and the 24V electrical system. Compared with a battery, a capacitor has the advantages of low price, small mass and small volume, which is convenient for layout, and does not require cooling. Moreover, in combination with the control method of the 48V mild hybrid system, it can ensure that the power of the 48V pseudocapacitor can meet the energy required for driving assistance, exhaust gas heating, and starting, enabling the vehicle to be stably and normally used. By maintaining the normal operation of driving assistance, energy recovery, and starting, the fuel consumption of the vehicle is ultimately reduced.

Description

Technical Field

[0001] This application relates to the field of automotive electronics and electrical systems, and particularly to a 48V mild hybrid system and its control method. Background Art

[0002] As the country pays more and more attention to environmental protection, it has become an inevitable choice to produce more energy-efficient vehicles, whether for passenger cars or commercial vehicles. The 48V mild hybrid system of vehicles overcomes the problems of small power and large current in the voltage system. Compared with traditional vehicles and new energy vehicles with heavy hybridization, its cost has great cost performance. BSG (Belt-Driven Starter Generator) is the first choice for the 48V mild hybrid system of passenger cars, with cost performance advantages and high reliability.

[0003] In some related technologies, the 48V mild hybrid system can be divided into architectures such as P0, P1, P2, P2.5, P3, and P4 (P0, P1, P2, P2.5, P3, and P4 are the placement positions of the motor) according to the different positions of the motor relative to the powertrain. In the application of commercial vehicles, the entire electrical system is divided into a 48V electrical system part and a 24V electrical system part, and the two electrical systems are connected by DC / DC (Direct Current). The 48V accessory motor of the 48V electrical system has to undertake working conditions such as braking energy recovery, boosting, cold start, and hot start. 48V accessories such as exhaust gas electric heating are only used during cold start. In such usage environments, the power supply is required to have strong instantaneous charge and discharge characteristics. The existing architectures generally select 48V rate lithium batteries or large-capacity capacity batteries to meet the demand for large-rate charge and discharge in a short time, but there are the following problems:

[0004] In the prior art, 48V rate lithium batteries or large-capacity lithium batteries are selected to meet the demand for large-rate charge and discharge in a short time. Both rate lithium batteries or large-capacity lithium batteries are very expensive. A 10kwh battery is more than 10,000 yuan. In addition, a certain thermal management system needs to be designed for temperature control, which also increases the cost. Moreover, the charge and discharge times of lithium batteries are generally 3,000 times, and the service life cannot reach the lifetime of the whole vehicle.

[0005] Therefore, how to reduce production costs and ensure that operations such as braking energy recovery, boosting, cold start, hot start, and exhaust gas electric heating carried out by the 48V electrical system can work properly is an urgent problem to be solved. Summary of the Invention

[0006] The embodiments of the present application provide a 48V mild hybrid system and its control method to solve the cost problem and service life problem brought by using 48V rate lithium batteries or large-capacity capacity batteries in the related art.

[0007] In a first aspect, a 48V mild hybrid system is provided, which includes:

[0008] A 48V electrical system, which includes a 48V motor, a 48V electric heating device, and a 48V air conditioner connected to a 48V pseudocapacitor;

[0009] A 24V electrical system, which includes a 24V lead-acid battery and a vehicle-wide 24V electrical load connected to each other;

[0010] A DC / DC converter, which connects the 48V electrical system and the 24V electrical system.

[0011] Since the capacitor generally only needs a few seconds or minutes to charge, and the number of charge and discharge cycles of the capacitor is at least tens of thousands, while the battery needs several hours to charge and the number of charge and discharge cycles is generally only a few hundred or thousands, the 48V mild hybrid system of the present application is proposed to solve the cost problem and service life problem brought by using 48V rate lithium batteries or large-capacity capacity batteries.

[0012] In some embodiments, the 48V pseudocapacitor is a 48V pseudocapacitor with activated carbon added to the positive and negative electrode materials, the capacity of the 48V pseudocapacitor is 10 - 50AH, and the discharge rate is 10 - 80C.

[0013] In some embodiments, the 48V motor is a belt-driven motor and / or a gear-driven motor with a motor controller MCU and an inverter ACDC built in;

[0014] The 48V motor is used to start the engine, provide driving assistance, recover braking energy of the motor, and generate electricity during driving.

[0015] In some embodiments, the belt-driven motor is located on the engine gear train and is a BSG motor;

[0016] The gear-driven motor is located at P2.5.

[0017] In a second aspect, a control method for a 48V mild hybrid system is provided, which includes the following steps:

[0018] Provide a 48V mild hybrid system;

[0019] Preset the control modes of the 48V mild hybrid system corresponding to different trigger conditions and form a set library; the trigger conditions are the SOC values of the 48V pseudocapacitor and the 24V lead-acid battery, as well as the starting state and driving state of the vehicle;

[0020] Obtain the actual starting state and driving state of the vehicle, as well as the actual SOC values of the 48V pseudocapacitor and the 24V lead-acid battery through the vehicle controller, so as to select the corresponding triggering conditions;

[0021] According to the selected triggering conditions, run the corresponding control mode in the set library.

[0022] The 48V pseudocapacitor with both battery and capacitor characteristics is applied in the 48V mild hybrid system. Due to the characteristics of the 48V pseudocapacitor, corresponding energy control strategies need to be set to ensure that the power of the 48V pseudocapacitor can meet the energy required for driving assistance, exhaust gas heating, energy recovery, and engine starting, so that the vehicle can be used stably and normally. Therefore, the 48V mild hybrid system control method of this application is proposed to ensure the normal use and operation of the 48V mild hybrid system.

[0023] In some embodiments, when the triggering condition is cold start of the vehicle and the SOC value of the 48V pseudocapacitor is less than 80%, the control mode is: first close the DC / DC converter, and use the 24V lead-acid battery to charge the 48V pseudocapacitor until the SOC value of the 48V pseudocapacitor is greater than or equal to 90% and then stop; disconnect the DC / DC converter, and use the 48V pseudocapacitor to drive the 48V motor to drive the engine crankshaft to complete starting, and at the same time use the 48V pseudocapacitor to supply power to the 48V electric heating device;

[0024] When the triggering condition is hot start of the vehicle and the SOC value of the 48V pseudocapacitor is greater than 30% and less than 60%, the control mode is: close the DC / DC converter, and use the 24V lead-acid battery and the 48V pseudocapacitor to drive the 48V motor together to drive the engine crankshaft to complete starting;

[0025] When the triggering condition is hot start of the vehicle and the SOC value of the 48V pseudocapacitor is less than 30%, the control mode is: close the DC / DC converter, and the 24V lead-acid battery 4 charges the 48V pseudocapacitor through the DC / DC converter until the SOC value of the 48V pseudocapacitor reaches more than 30%, and the DC / DC converter remains closed. At this time, drive the 48V motor to drive the engine crankshaft to complete starting, and at the same time supply power to the 48V electric heating device; or, after the SOC value of the 48V pseudocapacitor reaches more than 30%, disconnect the DC / DC converter, and then drive the 48V motor to drive the engine crankshaft to complete starting, and at the same time supply power to the 48V electric heating device (2).

[0026] In some embodiments, when the triggering condition is vehicle parking or parking state and the SOC value of the 48V pseudocapacitor is less than 30%, the control mode is: use the 24V lead-acid battery to charge the 48V pseudocapacitor until the SOC value of the 48V pseudocapacitor is greater than 70% and then stop charging;

[0027] When the trigger condition is that the vehicle is in normal driving state and the SOC value of the 48V pseudocapacitor is less than 30%, the control mode is: start the driving power generation function, use the engine to drive the 48V motor to generate electricity, and charge the 48V pseudocapacitor; after the SOC value of the 48V pseudocapacitor is greater than 70%, turn off the driving power generation function.

[0028] In some embodiments, when the trigger condition is that a signal of stepping on the brake pedal is received and the SOC value of the 48V pseudocapacitor is less than 80%, the control mode is:

[0029] Use the engine to drive the 48V motor to generate electricity. On the premise of meeting the power consumption demand of the 48V electrical system, the 48V motor generates electricity and charges the surplus energy into the 48V pseudocapacitor, and the following operations are carried out during the charging process: when the SOC value of the 48V pseudocapacitor is between 80% and 95%, charge the 48V pseudocapacitor and the 24V lead-acid battery simultaneously; when the SOC value of the 48V pseudocapacitor is above 100%, stop charging the 48V pseudocapacitor and only charge the 24V lead-acid battery.

[0030] In some embodiments, when the trigger condition is that a signal of stepping on the accelerator pedal is received and the SOC value of the 48V pseudocapacitor is greater than 30%, the control mode is: the 48V pseudocapacitor outputs power to drive the 48V motor to operate, and the 48V motor transmits the assisting torque to the crankshaft pulley through a gear;

[0031] When the trigger condition is that a signal of stepping on the accelerator pedal is received and the SOC value of the 48V pseudocapacitor is less than 30%, the control mode is: the 24V lead-acid battery discharges to the 48V pseudocapacitor through a DC / DC converter to drive the 48V motor, and the 48V motor transmits the assisting torque to the crankshaft pulley through a gear.

[0032] In some embodiments, when the trigger condition is that the 48V air conditioner uses electricity during the vehicle driving process, the control mode is: the engine drives the 48V motor to actively generate electricity to supply power to the 48V air conditioner;

[0033] When the trigger condition is that the 48V air conditioner uses electricity during the vehicle parking process, the control mode is: use the 24V lead-acid battery to supply power to the 48V air conditioner through a DC / DC converter, and the following operations are carried out: when the SOC value of the 24V lead-acid battery is less than 50%, reduce the refrigeration power of the 48V air conditioner; when the SOC value of the 24V lead-acid battery is less than 30%, stop supplying power to the 48V air conditioner;

[0034] When the trigger condition is that the power consumption of the whole vehicle's 24V electrical load exceeds the limit value, the control mode is: use the 48V pseudocapacitor to discharge to the 24V lead-acid battery through a DC / DC converter.

[0035] The beneficial effects brought by the technical solution provided in this application include:

[0036] The embodiment of this application provides a 48V mild hybrid system. Since capacitors have the advantages of low price, small mass and small volume, which are convenient for layout compared with batteries, and do not require cooling. Generally, it only takes a few seconds or minutes to charge a capacitor, and the number of charge and discharge cycles of a capacitor is at least tens of thousands of times, while it takes several hours to charge a battery, and the number of charge and discharge cycles is generally only a few hundred or a thousand times. Therefore, the 48V rate lithium battery is replaced with a 48V pseudocapacitor to solve the cost problem and service life problem brought by using a 48V rate lithium battery or a large-capacity capacitive battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1 It is a schematic layout diagram of the 48V mild hybrid system provided by the embodiment of this application;

[0039] Figure 2 It is a schematic step diagram of the control method of the 48V mild hybrid system provided by the embodiment of this application.

[0040] In the figure: 1. 48V motor; 2. 48V electric heating device; 3. 48V air conditioner; 4. 24V lead-acid battery; 5. 24V electrical load for the whole vehicle; 6. DC / DC converter; 7. 48V pseudocapacitor. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] To make the objectives, technical solutions and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments in this application belong to the scope of protection of this application.

[0042] Capacitors have the advantages of low price, small mass and small volume, which are convenient for layout compared with batteries, and do not require cooling. Generally, it only takes a few seconds or minutes to charge a capacitor, and the number of charge and discharge cycles of a capacitor is at least tens of thousands of times, while it takes several hours to charge a battery, and the number of charge and discharge cycles is generally only a few hundred or a thousand times. Therefore, the 48V mild hybrid system of this application is proposed to solve the cost problem and service life problem brought by using a 48V rate lithium battery or a large-capacity capacitive battery.

[0043] However, the charge and discharge curve of the capacitor is steep, which is suitable for fast charging and discharging with large current and high power, and is beneficial to the charging process. However, the voltage drops rapidly, and it is difficult to maintain sufficient power for a long time. Therefore, according to the above characteristics, a 48V pseudocapacitor 7 with both battery and capacitor characteristics is used in the 48V mild hybrid system. Due to the characteristics of the 48V pseudocapacitor, corresponding energy control strategies need to be set to ensure that the power of the 48V pseudocapacitor 7 can meet the energy required for driving assistance, exhaust gas heating, energy recovery, and engine starting, so that the vehicle can be used stably and normally. Therefore, the 48V mild hybrid system control method of this application is proposed to ensure the normal use and operation of the 48V mild hybrid system.

[0044] The following will describe in detail the specific composition structure of a 48V mild hybrid system.

[0045] Please refer to Figure 1 , a 48V mild hybrid system, which includes:

[0046] A 48V electrical system, which includes a 48V motor 1, a 48V electric heating device 2, and a 48V air conditioner 3 connected to the 48V pseudocapacitor 7; the 48V pseudocapacitor 7 provides the required power for the 48V motor 1 under conditions such as assistance, energy recovery, active power generation, and starting. The 48V electric heating device 2 is located at the front end of the vehicle's DOC and heats the exhaust gas during cold start to reduce the emissions of CH and NOX during starting. The 48V air conditioner 3 can refrigerate during driving and parking.

[0047] A 24V electrical system, which includes a connected 24V lead-acid battery 4 and a vehicle-wide 24V electrical load 5; in the 24V electrical system, the 24V lead-acid battery 4 provides the energy for the vehicle-wide 24V power grid (vehicle-wide 24V electrical load 5), and provides the energy required for the 48V air conditioner 3 during parking and driving; a DC / DC converter 6, which connects the 48V electrical system and the 24V electrical system through DCDC and can convert the electrical energy of the 48V electrical system and the 24V electrical system according to different usage requirements.

[0048] Since the capacitor generally only takes a few seconds or minutes to charge, and the number of charge and discharge cycles of the capacitor is at least tens of thousands, while the battery takes several hours to charge and the number of charge and discharge cycles is generally only a few hundred or thousands, the 48V mild hybrid system of this application is proposed to solve the cost problem and service life problem brought by using a 48V rate lithium battery or a large-capacity capacitive battery.

[0049] In some preferred embodiments, the 48V pseudocapacitor 7 is a 48V pseudocapacitor 7 with activated carbon added to the positive and negative electrode materials. The activated carbon improves the rate performance of the 48V pseudocapacitor during discharge. The capacity of the 48V pseudocapacitor 7 is between 10 - 50AH, and the discharge rate is 10 - 80C. The 48V pseudocapacitor 7 does not require cooling and has the characteristics of small mass, small volume, and convenient layout.

[0050] The rated power of the 48V motor 1 is 20 - 30KW, and the rated torque is 10 - 80Nm. The 48V motor 1 is a belt-driven motor with a built-in motor controller MCU and an inverter ACDC; the 48V motor 1 is a gear-driven motor with a built-in motor controller MCU and an inverter ACDC; or part of it is a belt-driven motor and the other part is a gear-driven motor. The 48V motor 1 is used for starting the engine, providing driving assistance, recovering the braking energy of the motor, and generating electricity while driving.

[0051] Furthermore, the belt-driven motor is located on the engine gear train and is a BSG motor; the gear-driven motor can be located at P2.5 or at other positions.

[0052] In some preferred embodiments, the power of the 48V electric heating device 2 is 5 - 20KW, and the electric heating time is 40 - 80s; the power of the 48V air conditioner 3 is 1 - 3KW, and the capacity of the 24V lead-acid battery 4 is preferably 330AH, but is not limited to this capacity.

[0053] A control method for a 48V mild hybrid system includes the following steps:

[0054] 100. Provide the above-mentioned 48V mild hybrid system;

[0055] 101. Preset the control modes of the 48V mild hybrid system corresponding to different trigger conditions and form a set library; the trigger conditions are the SOC values of the 48V pseudocapacitor 7 and the 24V lead-acid battery 4, as well as the starting state and driving state of the vehicle, and are not limited to these conditions;

[0056] 102. Obtain the actual starting state and driving state of the vehicle, as well as the actual SOC values of the 48V pseudocapacitor 7 and the 24V lead-acid battery 4 through the vehicle controller to select the corresponding trigger conditions;

[0057] 103. According to the selected trigger conditions, run the corresponding control mode in the set library.

[0058] Through the above steps, different control modes are run according to the starting state and driving state of different vehicles, as well as the SOC values of the 48V pseudocapacitor 7 and the 24V lead-acid battery 4. Through different triggering conditions, the control modes that are run can ensure that the power of the 48V pseudocapacitor 7 can meet the energy required for driving assistance, exhaust gas heating, and starting, enabling the vehicle to be used stably and normally. By maintaining the normal operation of driving assistance, energy recovery, and starting, the fuel consumption of the vehicle is ultimately reduced.

[0059] In some preferred embodiments, when the vehicle needs to be started, the following solutions are available:

[0060] When the triggering condition is a cold start of the vehicle and the SOC value of the 48V pseudocapacitor 7 is less than 80%, the control mode is as follows: First, close the DC / DC converter 6, and use the 24V lead-acid battery 4 to charge the 48V pseudocapacitor 7 until the SOC value of the 48V pseudocapacitor 7 is greater than or equal to 90% and then stop; disconnect the DC / DC converter 6, and use the 48V pseudocapacitor 7 to drive the 48V motor 1. The 48V motor 1 transmits the starting torque to the engine crankshaft through a gear to drive the engine crankshaft to complete the start. At the same time, use the 48V pseudocapacitor 7 to supply power to the 48V electric heating device 2, and the 48V electric heating device 2 supplies power to heat the exhaust gas, so as to reduce the emissions of CH and NOX during starting;

[0061] When the triggering condition is a hot start of the vehicle and the SOC value of the 48V pseudocapacitor 7 is greater than 30% and less than 60%, the control mode is as follows: Close the DC / DC converter 6, and use the 24V lead-acid battery 4 and the 48V pseudocapacitor 7 to discharge together to drive the 48V motor 1. The 48V motor 1 transmits the starting torque to the engine crankshaft through a gear to drive the engine crankshaft to complete the start;

[0062] When the triggering condition is a hot start of the vehicle and the SOC value of the 48V pseudocapacitor 7 is less than 30%, the control mode is as follows: Close the DC / DC converter 6, and the 24V lead-acid battery 4 charges the 48V pseudocapacitor 7 through the DC / DC converter 6 until the SOC value of the 48V pseudocapacitor 7 reaches more than 30%. The DC / DC converter 6 remains closed. At this time, the 48V motor 1 can be driven to drive the engine crankshaft to complete the start, and at the same time, power is supplied to the 48V electric heating device 2; among them, the electric heating device 2 will only start and start heating when the catalyst temperature is low.

[0063] Or it is also possible to disconnect the DC / DC converter 6 after the SOC value of the 48V pseudocapacitor 7 reaches more than 30%, and then drive the 48V motor 1 to drive the engine crankshaft to complete the start, and at the same time, power is supplied to the 48V electric heating device 2.

[0064] It should be understood that during this process, whether the DC / DC converter 6 is closed or not does not affect the driving of the 48V motor, but only makes a difference in whether to continue charging the 48V pseudocapacitor 7 or not after reaching the starting condition.

[0065] The above three modes all utilize the fast charge and discharge characteristics of the 48V pseudocapacitor 7 and cooperate with the 24V lead-acid battery 4 to stably and continuously obtain the large current required for vehicle starting.

[0066] In some preferred embodiments, during the normal driving process of the vehicle and during the parking process, the normal driving process is the situation where the brake is not depressed or the accelerator is deeply depressed; since the electric energy in the 48V pseudocapacitor 7 will decrease due to the use of the 48V air conditioner 3, in order to ensure that the 48V pseudocapacitor 7 and the 24V lead-acid battery 4 have sufficient power, there are the following solutions:

[0067] When the trigger condition is that the vehicle is in a parked or stationary state and the SOC value of the 48V pseudocapacitor 7 is less than 30%, the control mode is: using the 24V lead-acid battery 4 to charge the 48V pseudocapacitor 7 until the SOC value of the 48V pseudocapacitor 7 is greater than 70% and then stopping the charging;

[0068] When the trigger condition is that the vehicle is in a normal driving state and the SOC value of the 48V pseudocapacitor 7 is less than 30%, the control mode is: starting the driving power generation function, using the engine to drive the 48V motor 1 to generate electricity and charge the 48V pseudocapacitor 7; until the SOC value of the 48V pseudocapacitor 7 is greater than 70%, then turning off the driving power generation function.

[0069] When the vehicle changes from the parked state to the normal driving state (i.e., from the state of waiting for a red light to the vehicle starting), during this process, the SOC value of the 48V pseudocapacitor 7 and the SOC value of the 24V lead-acid battery 4 are not judged, and the charging process is not carried out to avoid affecting the normal driving of the vehicle.

[0070] In some preferred embodiments, when the vehicle is driving normally and the brake pedal is suddenly depressed, which is a deceleration process, in order to realize the energy recovery during this process and ensure that the 48V pseudocapacitor 7 and the 24V lead-acid battery 4 have sufficient power, there are the following solutions:

[0071] When the trigger condition is receiving the signal of depressing the brake pedal and the SOC value of the 48V pseudocapacitor 7 is less than 80%, the control mode is:

[0072] The engine is used to reversely drive the 48V motor 1 to generate electricity. On the premise of meeting the power consumption requirements of the 48V electrical system, the 48V motor 1 generates electricity and charges the surplus energy into the 48V pseudocapacitor 7, and the following operations are performed during the charging process: when the SOC value of the 48V pseudocapacitor 7 is between 80% and 95%, the 48V pseudocapacitor 7 and the 24V lead-acid battery 4 are charged simultaneously; when the SOC value of the 48V pseudocapacitor 7 is 100%, the charging of the 48V pseudocapacitor 7 is stopped, and only the 24V lead-acid battery 4 is charged.

[0073] This is to ensure that when the 48V pseudocapacitor 7 can no longer be charged, the maximum amount of energy recovery is achieved, and the electric energy converted from the recovered energy is sent into the 24V lead-acid battery 4 for storage.

[0074] In some preferred embodiments, when the vehicle needs to enhance the power output when encountering a steep slope and when the vehicle overtakes, to save fuel consumption, the 48V motor 1 provides assistance, and there are the following corresponding solutions:

[0075] When the trigger condition is receiving a signal of stepping on the accelerator pedal and the SOC value of the 48V pseudocapacitor 7 is greater than 30%, the control mode is: the 48V pseudocapacitor 7 outputs power to drive the 48V motor 1 to operate, and the 48V motor 1 transmits the assistance torque to the crankshaft pulley through the gear;

[0076] In some preferred embodiments, when using the air conditioner, there are the following solutions:

[0077] When the trigger condition is that the 48V air conditioner 3 uses electricity during vehicle driving, the control mode is: the engine drives the 48V motor 1 to actively generate electricity to supply power to the 48V air conditioner 3;

[0078] When the trigger condition is that the 48V air conditioner 3 uses electricity during vehicle parking, the control mode is: the 24V lead-acid battery 4 supplies power to the 48V air conditioner 3 through the DC / DC converter 6, and the following operations are performed: when the SOC value of the 24V lead-acid battery 4 is less than 50%, the cooling power of the 48V air conditioner 3 is reduced; when the SOC value of the 24V lead-acid battery 4 is less than 30%, the power supply to the 48V air conditioner 3 is stopped;

[0079] When the trigger condition is that the power consumption of the whole vehicle's 24V electrical load 5 exceeds the limit value, the control mode is: the 48V pseudocapacitor 7 discharges to the 24V lead-acid battery 4 through the DC / DC converter 6.

[0080] It should be understood that: when the above control modes are running, there is no limitation on the sequence or single-line operation. During normal use, multiple control modes usually run simultaneously, so as to reduce fuel consumption when all vehicle functions are working properly. Moreover, the judgment values such as 30%, 60%, 70%, 80%, 95%, 100% above can be specifically set according to the specific capacity of the 48V pseudocapacitor 7. We can consider that the energy required for each auxiliary operation of the 48V pseudocapacitor 7 is roughly constant. However, when the capacity of the 48V pseudocapacitor 7 changes, the electrical energy represented by 30%, 60%, 70%, 80%, 95%, 100% after the change is different. Therefore, the above judgment values will change, which applies to this application including but not limited to the claimed judgment values.

[0081] Next, this application also presents actual operation cases of the above 48V mild hybrid system in different regions:

[0082] First, in Mohe, Heilongjiang, at -30 degrees Celsius, when starting the engine, the PCU detects that the capacity of the 48V pseudocapacitor 7 is 60%. At this time, the DC / DC converter 6 is closed, and the 24V lead-acid battery 4 charges the 48V pseudocapacitor 7 with a capacity of 48V / 12AH. When the capacity of the 48V pseudocapacitor 7 with a capacity of 48V / 12AH reaches 90%, the PCU prompts that starting is possible. At this time, the energy possessed by the 48V pseudocapacitor 7 is 0.5184 KWH. Then, turn the engine key to start. At this time, the 48V pseudocapacitor 7 provides the energy required for starting for the 48V motor 1. It is estimated that 30KW * 10S = 0.08 KWH. After starting, the 48V pseudocapacitor 7 provides the required energy for the electric heating for 50s, with an estimated 10KW * 50S = 0.139 KWH.

[0083] Second, in Wuhan, Hubei, at 20 degrees Celsius, when the truck stops temporarily due to waiting for a red light, the PCU detects that the capacity of the 48V pseudocapacitor 7 is 60% and the engine stops. When the green light comes on, the 48V pseudocapacitor 7 and the 24V lead-acid battery 4 provide energy together. The 48V motor 1 at the P2.5 position drives the crankshaft pulley through the gear to bring the engine to idle speed, and then fuel injection is carried out to start the engine.

[0084] In the above cases, using the 48V pseudocapacitor 7 and combining with the above control method can ensure the normal operation of the vehicle, thus achieving the purpose of cost reduction compared with using a 48V battery.

[0085] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application. Unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0086] It should be noted that in the present application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the said element.

[0087] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A control method for a 48V mild hybrid system, characterized in that, The 48V mild hybrid system includes: a 48V electrical system, which includes a 48V motor (1), a 48V electric heating device (2), and a 48V air conditioner (3) connected to a 48V pseudocapacitor (7); a 24V electrical system, which includes a 24V lead-acid battery (4) and a vehicle-wide 24V electrical load (5) connected to each other; a DC / DC converter (6) that connects the 48V electrical system and the 24V electrical system; The control method of the 48V mild hybrid system includes the following steps: Preset the control modes of the 48V mild hybrid system corresponding to different trigger conditions and form a set library; the trigger conditions are the SOC values of the 48V pseudocapacitor (7) and the 24V lead-acid battery (4), as well as the starting state and driving state of the vehicle; Obtain the actual starting state and driving state of the vehicle, as well as the actual SOC values of the 48V pseudocapacitor (7) and the 24V lead-acid battery (4) through the vehicle controller, so as to select the corresponding trigger condition; According to the selected trigger condition, run the corresponding control mode in the set library; When the trigger condition is cold start of the vehicle and the SOC value of the 48V pseudocapacitor (7) is less than 80%, the control mode is: first close the DC / DC converter (6), use the 24V lead-acid battery (4) to charge the 48V pseudocapacitor (7) until the SOC value of the 48V pseudocapacitor (7) is greater than or equal to 90% and then stop; disconnect the DC / DC converter (6), and use the 48V pseudocapacitor (7) to drive the 48V motor (1) to drive the engine crankshaft to complete the start, and at the same time use the 48V pseudocapacitor (7) to supply power to the 48V electric heating device (2); When the trigger condition is hot start of the vehicle and the SOC value of the 48V pseudocapacitor (7) is greater than 30% and less than 60%, the control mode is: close the DC / DC converter (6), and use the 24V lead-acid battery (4) and the 48V pseudocapacitor (7) together to drive the 48V motor (1) to drive the engine crankshaft to complete the start; When the trigger condition is hot start of the vehicle and the SOC value of the 48V pseudocapacitor (7) is less than 30%, the control mode is: close the DC / DC converter (6), the 24V lead-acid battery 4 charges the 48V pseudocapacitor (7) through the DC / DC converter (6) until the SOC value of the 48V pseudocapacitor (7) reaches more than 30%, the DC / DC converter (6) remains closed, and at this time drive the 48V motor (1) to drive the engine crankshaft to complete the start and supply power to the 48V electric heating device (2) at the same time; or, after the SOC value of the 48V pseudocapacitor (7) reaches more than 30%, disconnect the DC / DC converter (6), and then drive the 48V motor (1) to drive the engine crankshaft to complete the start and supply power to the 48V electric heating device (2) at the same time.

2. The control method of the 48V mild hybrid system according to claim 1, wherein: When the triggering condition is that the vehicle is in a parked or stationary state and the SOC value of the 48V pseudocapacitor (7) is less than 30%, the control mode is: charging the 48V pseudocapacitor (7) with the 24V lead-acid battery (4) until the SOC value of the 48V pseudocapacitor (7) is greater than 70% and then stopping the charging; When the triggering condition is that the vehicle is in a normal driving state and the SOC value of the 48V pseudocapacitor (7) is less than 30%, the control mode is: starting the driving power generation function, using the engine to drive the 48V motor (1) to generate electricity and charge the 48V pseudocapacitor (7); until the SOC value of the 48V pseudocapacitor (7) is greater than 70%, turning off the driving power generation function.

3. The control method of the 48V mild hybrid system according to claim 1, characterized in that: When the triggering condition is receiving a signal of stepping on the brake pedal and the SOC value of the 48V pseudocapacitor (7) is less than 80%, the control mode is: Using the engine to drive the 48V motor (1) to generate electricity, and on the premise of meeting the power consumption requirements of the 48V electrical system, the 48V motor (1) generates electricity and charges the surplus energy into the 48V pseudocapacitor (7), and the following operations are carried out during the charging process: when the SOC value of the 48V pseudocapacitor (7) is between 80% and 95%, charging the 48V pseudocapacitor (7) and the 24V lead-acid battery (4) simultaneously; when the SOC value of the 48V pseudocapacitor (7) is above 100%, stopping charging the 48V pseudocapacitor (7) and only charging the 24V lead-acid battery (4).

4. The control method of the 48V mild hybrid system according to claim 1, characterized in that: When the triggering condition is receiving a signal of stepping on the accelerator pedal and the SOC value of the 48V pseudocapacitor (7) is greater than 30%, the control mode is: the 48V pseudocapacitor (7) outputs power to drive the 48V motor (1) to operate, and the 48V motor (1) transmits the assisting torque to the crankshaft pulley through the gear; When the triggering condition is receiving a signal of stepping on the accelerator pedal and the SOC value of the 48V pseudocapacitor (7) is less than 30%, the control mode is: the 24V lead-acid battery (4) discharges to the 48V pseudocapacitor (7) through the DC / DC converter (6) to drive the 48V motor (1), and the 48V motor (1) transmits the assisting torque to the crankshaft pulley through the gear.

5. The control method of the 48V mild hybrid system according to claim 1, characterized in that: When the triggering condition is that the 48V air conditioner (3) consumes electricity during the vehicle driving process, the control mode is: the engine drives the 48V motor (1) to actively generate electricity to supply power to the 48V air conditioner (3); When the triggering condition is that the 48V air conditioner (3) consumes electricity during the vehicle parking process, the control mode is: using the 24V lead-acid battery (4) to supply power to the 48V air conditioner (3) through the DC / DC converter (6), and the following operations are carried out: when the SOC value of the 24V lead-acid battery (4) is less than 50%, reducing the cooling power of the 48V air conditioner (3); when the SOC value of the 24V lead-acid battery (4) is less than 30%, stopping supplying power to the 48V air conditioner (3); When the triggering condition is that the consumption of the vehicle's 24V electrical load (5) exceeds the limit value, the control mode is: the 48V pseudocapacitor (7) discharges to the 24V lead-acid battery (4) through the DC / DC converter (6).

6. The control method of the 48V mild hybrid system according to claim 1, characterized in that: The 48V pseudocapacitor (7) is a 48V pseudocapacitor with activated carbon added to the positive and negative electrode materials. The capacity of the 48V pseudocapacitor (7) is 10 - 50AH, and the discharge rate is 10 - 80C.

7. The control method of the 48V mild hybrid system according to claim 1, characterized in that: The 48V motor (1) is a belt-driven motor and / or a gear-driven motor with a motor controller MCU and an inverter ACDC built in; The 48V motor (1) is used for starting the engine, providing driving assistance, recovering the braking energy of the motor, and generating electricity during driving.

8. The control method of the 48V mild hybrid system according to claim 7, characterized in that: The belt-driven motor is located on the engine gear train and is a BSG motor; The gear-driven motor is located at P2.5.

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