Energy distribution method and control method of mild hybrid system and mild hybrid system

Abstract

The embodiment of the present invention provides an energy distribution method, a control method and a mild hybrid system of a mild hybrid system, in which the target power P of the electric supercharger is met. ESC and the power P of the DCDC inverter DCDC Under the premise of BSG According to the power limit P BSG , get the current limit value I of BSG BSG , according to the current limit I BSG , obtain the torque limit Tq of BSG; the torque limit Tq of BSG is used when the power limit P BSG The maximum output torque, that is, the maximum torque that the BSG can output under the premise of the normal operation of the electric supercharger and the DCDC inverter, controls the output torque of the BSG to be less than the torque limit Tq. The energy of the battery provides energy to the BSG under the premise of ensuring the normal operation of the electric supercharger and the DCDC inverter. The energy of the mild hybrid system is reasonably distributed, thereby giving priority to the performance of the electric supercharger.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicle charging, and in particular to an energy distribution method and a control method of a mild hybrid system and a mild hybrid system. Background Art

[0002] The 48V mild hybrid system is a low-cost fuel-saving technology for vehicles, and has been mass-produced and applied in many models. The common P0 configuration 48V mild hybrid system mainly includes three major components: 48V battery, electric supercharger, DCDC inverter and belt-driven starter generator (BSG); BSG can save fuel by recovering energy during vehicle coasting and braking and optimizing the engine operating point. On the other hand, it can release the recovered energy to assist the engine in conditions that require rapid acceleration such as vehicle starting and overtaking, thereby improving drivability.

[0003] The electric supercharger can achieve rapid air replenishment and reduce the "turbo lag" phenomenon inherent in exhaust gas turbocharged engines, thereby improving the dynamic response of the engine and improving drivability.

[0004] At present, the power of mainstream 48V lithium batteries is about 12kw, the maximum power of electric superchargers is 5kw, and the maximum power of BSG is 10kw. When the electric supercharger and BSG are installed in the 48V mild hybrid system at the same time, the power of the 48V battery will be slightly insufficient, and there is also a risk of exceeding the safety upper limit of the 48V bus current. On the one hand, the instantaneous peak current enabled by both may exceed 350A, which will cause safety risks to the 48V battery and also affect the power-assisting performance of both the electric supercharger and BSG; on the other hand, because the electric supercharger is more efficient in utilizing 48V electric energy in terms of engine assistance than the BSG, that is, to achieve the same engine assistance effect, the electric supercharger requires less electricity.

[0005] In the prior art, there is a technical problem that the battery energy in the mild hybrid system is not reasonably distributed, resulting in poor transient response of the engine and vehicle drivability, low engine assist efficiency, and the risk of exceeding the safe upper limit of the battery bus current. Summary of the invention

[0006] In order to solve the above problems, the purpose of the present invention is to provide an energy distribution method for a mild hybrid system, which is used to solve the technical problems in the prior art that the battery energy in the mild hybrid system is not reasonably distributed, resulting in poor transient response of the engine and vehicle drivability, low engine assist efficiency, and the risk of exceeding the safety upper limit of the battery bus current.

[0007] To solve the above technical problems, the embodiments of the present invention adopt the following technical solutions:

[0008] A method for distributing energy in a mild hybrid system, the control method comprising the following steps:

[0009] The battery temperature is obtained and the battery temperature is compared with the preheating temperature threshold and the heating temperature respectively. The energy allocation method comprises the following steps:

[0010] Get the target power P of the electric supercharger ESC and the power P of the DCDC inverter DCDC ;

[0011] According to the target power P ESC and the power P DCDC , obtain the BSG power limit P BSG ;

[0012] According to the power limit P BSG , get the current limit value I of BSG BSG ;

[0013] According to the current limit I BSG , obtain the torque limit Tq of the BSG and control the output torque of the BSG to be less than the torque limit Tq.

[0014] Furthermore, the target power P of the electric supercharger is obtained. ESC include:

[0015] Get the intake mass flow rate m of the electric supercharger air and the enthalpy change △h after the electric supercharger s ;

[0016] The intake air mass flow rate m air and the enthalpy change Δh s Substitute into the first preset formula to calculate and obtain the target power P of the electric supercharger ESC ;

[0017] Among them, the first preset formula is P ESC =m air ·Δh s .

[0018] Furthermore, the acquisition of the intake mass flow rate m of the electric supercharger air include:

[0019] Get the constant pressure specific heat capacity C of air P , Intake air temperature upstream of the electric supercharger T in , a target boost pressure ratio PR and an air adiabatic index k for control of the electric supercharger;

[0020] The constant pressure specific heat capacity of air C P , Intake air temperature upstream of the electric supercharger Tin , the target boost pressure ratio PR and the air adiabatic index k of the electric supercharger for control are substituted into the second preset formula for calculation to obtain the intake mass flow rate m of the electric supercharger air ;

[0021] The second preset formula is:

[0022] Furthermore, the constant pressure specific heat capacity of air C P It is 1.004 kJ / kg·k, and the air insulation index k is 1.4.

[0023] Furthermore, the power P of the DCDC inverter is obtained DCDC include:

[0024] Get the current I of the DCDC inverter DCDC and the voltage U of the DCDC inverter DCDC ;

[0025] The current I of the DCDC inverter DCDC and the voltage U of the DCDC inverter DCDC Calculate and obtain the power P of the DCDC inverter DCDC .

[0026] Further, the current limit value I BSG , obtaining the torque limit value Tq of BSG includes:

[0027] The current limit I BSG Process according to preset rules to obtain the torque limit Tq of BSG.

[0028] An embodiment of the present invention further provides a control method for a mild hybrid system, the control method comprising:

[0029] Get the battery SOC;

[0030] comparing the SOC with a first preset ratio and a second preset ratio respectively;

[0031] When the SOC is greater than the first preset ratio, the energy distribution method of the mild hybrid system is executed;

[0032] When the SOC is between the first preset ratio and the second preset ratio, the enabling of the BSG is interrupted and the electric supercharger is requested to be enabled;

[0033] When the SOC is less than the second preset ratio, enabling of the BSG and the electric supercharger is interrupted.

[0034] Furthermore, the first preset ratio is 30%; and the second preset ratio is 20%.

[0035] An embodiment of the present invention further provides a mild hybrid system, wherein the electronic control unit is electrically connected to a battery, an electric supercharger, a DCDC inverter and a BSG, respectively, and the battery is electrically connected to an electric supercharger, a DCDC inverter and a BSG, respectively;

[0036] The electronic control unit realizes energy distribution between the electric supercharger and the BSG according to the energy distribution method of the mild hybrid system described in any one of claims 1 to 7, or controls the working state of the electric supercharger and the BSG according to the control method of the mild hybrid system described in claim 8 or 9.

[0037] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0038] The energy distribution method of the mild hybrid system provided by the embodiment of the present invention comprises the following steps: obtaining the target power P of the electric supercharger ESC and the power P of the DCDC inverter DCDC ; According to the target power P ESC and the power P DCDC , obtain the BSG power limit P BSG According to the power limit P BSG , get the current limit value I of BSG BSG According to the current limit I BSG , obtain the torque limit Tq of the BSG and control the output torque of the BSG to be less than the torque limit Tq.

[0039] In the energy distribution method of the mild hybrid system provided in the embodiment of the present invention, the target power P of the electric supercharger is met. ESC and the power P of the DCDC inverter DCDC Under the premise of BSG ; The power limit P BSG The maximum power that the battery can provide to the BSG under the premise that the electric supercharger and the DCDC inverter are working normally is calculated according to the power limit P. BSG , get the current limit value I of BSG BSG , according to the current limit I BSG , obtain the torque limit Tq of BSG; the torque limit Tq of BSG is used when the power limit P BSGThe maximum torque output, that is, the maximum torque that the BSG can output under the premise that the electric supercharger and the DCDC inverter work normally, controls the output torque of the BSG to be less than the torque limit Tq, and the energy of the battery provides energy to the BSG under the premise that the electric supercharger and the DCDC inverter work normally; by reasonably allocating the energy of the mild hybrid system, since the electric supercharger has a higher efficiency in utilizing electric energy than the BSG, the performance of the electric supercharger is given priority, and then energy is provided to the BSG, thereby improving the transient response of the engine and the drivability of the vehicle;

[0040] At the same time, it also avoids the risk of exceeding the safe upper limit of the bus current of the mild hybrid system when the electric supercharger and BSG are installed in the mild hybrid system at the same time. It solves the technical problem in the prior art that the battery energy in the mild hybrid system is not reasonably distributed, resulting in poor transient response of the engine and vehicle drivability, low engine assist efficiency, and the risk of exceeding the safe upper limit of the battery bus current.

[0041] In addition, the torque limit Tq of the BSG is obtained by calculation and the output torque of the BSG is controlled to be less than the torque limit Tq; the energy distribution effect is achieved at the software control angle level without the need for additional hardware for control. The method is simple, easy to operate and implement, and can reduce the additional cost brought by upgrading the hardware design.

[0042] The present invention also provides a control method for a mild hybrid system, wherein the control method switches and distributes the energy of the mild hybrid system using different working modes according to the SOC of the battery, thereby avoiding excessive power consumption of the mild hybrid system and improving the sustainability of power supply of the mild hybrid system.

[0043] The present invention also provides a mild hybrid system, which ensures that the performance of the electric supercharger is given priority and then provides energy to the BSG, thereby improving the transient response of the engine and the drivability of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0045] Figure 1 is a flow chart of an energy distribution method for a mild hybrid system provided by an embodiment of the present invention;

[0046] Figure 2is a flow chart of a control method of a mild hybrid system provided by an embodiment of the present invention;

[0047] Figure 3 is a logic diagram of a control method for a mild hybrid system provided by an embodiment of the present invention;

[0048] Figure 4 4 is a system block diagram of a mild hybrid system provided by an embodiment of the present invention.

[0049] in:

[0050] 100. Electronic control unit; 200. Battery; 300. Electric supercharger; 400. DCDC inverter; 500. BSG. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0052] In the description of the embodiments of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the embodiments of the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0053] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a replaceable connection, or an integral connection, it can be a mechanical connection, it can be an electrical connection, it can be a direct connection, it can be indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0054] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0055] like Figure 1As shown, this embodiment provides an energy distribution method for a mild hybrid system, and the energy distribution method includes the following steps:

[0056] Get the target power P of the electric supercharger ESC and the power P of the DCDC inverter DCDC ;

[0057] In order to give priority to the mild hybrid system supplying power to the electric supercharger, the first step is to calculate the target power P of the electric supercharger enabling process. ESC The mild hybrid system in this embodiment is a 48V mild hybrid system, wherein the power of the 48V lithium battery is 12kw. The target power P of the electric supercharger ESC The power required for the electric supercharger to work normally.

[0058] The target power P of the electric supercharger is obtained ESC Specifically include:

[0059] Get the intake mass flow rate m of the electric supercharger air and the enthalpy change △h after the electric supercharger s ;

[0060] The intake air mass flow rate m air and the enthalpy change Δh s Substitute into the first preset formula to calculate and obtain the target power P of the electric supercharger ESC ;

[0061] Among them, the first preset formula is P ESC =m air ·Δh s .

[0062] The method of obtaining the intake mass flow rate m of the electric supercharger air include:

[0063] Get the constant pressure specific heat capacity C of air P , Intake air temperature upstream of the electric supercharger T in , a target boost pressure ratio PR and an air adiabatic index k for control of the electric supercharger;

[0064] The constant pressure specific heat capacity of air C P , Intake air temperature upstream of the electric supercharger T in , the target boost pressure ratio PR and the air adiabatic index k of the electric supercharger for control are substituted into the second preset formula for calculation to obtain the intake mass flow rate m of the electric supercharger air ;

[0065] The second preset formula is:

[0066] Among them, the constant pressure specific heat capacity of air C P is 1.004 kJ / kg·k, and the air adiabatic index k is 1.4. The PR is the target boost pressure ratio for control of the electric supercharger after PID compensation. The target boost pressure ratio PR comes from the control software logic of the electric supercharger, that is, it can be directly read when reading the parameters of the electric supercharger; m air It can be measured by the HFM air mass flow meter on the engine; T in It can be obtained by the temperature and pressure sensor arranged on the engine intake pipe.

[0067] The DCDC inverter is an inverter between the 48V lithium battery and the 12V electrical network system. It is responsible for allocating the power supply from the 48V lithium battery to the 12V electrical network system during the operation of the vehicle. Generally, the power change range is not large.

[0068] The power P of the DCDC inverter is obtained DCDC include:

[0069] Get the current I of the DCDC inverter DCDC and the voltage U of the DCDC inverter DCDC ;

[0070] The current I of the DCDC inverter DCDC and the voltage U of the DCDC inverter DCDC Calculate and obtain the power P of the DCDC inverter DCDC .

[0071] The DCDC inverter current I DCDC The voltage of the DCDC inverter is sent by the DCDC inverter to the CAN network and received by the EMS software, that is, the current I of the DCDC inverter can be directly obtained by reading the parameters of the DCDC inverter. DCDC and the voltage of the DCDC inverter, the power P of the DCDC inverter DCDC is the power consumed by DCDC.

[0072] According to the target power P ESC and the power P DCDC , obtain the BSG power limit P BSG ;

[0073] BSG uses power limit P BSG Power P from 48V lithium battery cell Subtract the target power P of the electric supercharger ESC And the DCDC power P DCDC Get, that is:

[0074] P BSG =P cell -P ESC -P DCDC

[0075] Among them, the power P of the 48V lithium battery cell Provided by the battery manufacturer supplier, that is, the power P of the 48V lithium battery can be directly obtained by reading the parameters of the 48V lithium battery cell ;

[0076] According to the power limit P BSG , get the current limit value I of BSG BSG ;

[0077] The BSG current limit I BSG The specific way to obtain is:

[0078] I BSG =P BSG ÷U BSG

[0079] Among them, the voltage U of BSG BSG Approximately equal to the voltage U of the DCDC inverter DCDC (ignore the thread voltage drop loss), it can also be obtained through the signal sent by BSG to the CAN network, that is, directly read the parameters of BSG.

[0080] According to the current limit I BSG , obtain the torque limit Tq of the BSG and control the output torque of the BSG to be less than the torque limit Tq.

[0081] Wherein, the current limit value I BSG , obtaining the torque limit value Tq of BSG specifically includes:

[0082] The current limit I BSG Process according to preset rules to obtain the torque limit Tq of BSG.

[0083] The preset rule may be to search directly on the map table, that is, to set the current limit value I BSG Search directly on the map table and read the torque limit value Tq directly from the map table; the preset rule can also be directly filled in by using a function formula or a model. BSG The torque limit value Tq of BSG is obtained by calculation.

[0084] The following table is a simple table of maps:

[0085]

[0086]

[0087] On the premise that the electric supercharger and DCDC inverter are satisfied first, the 48V lithium battery of the mild hybrid system first provides power to the electric supercharger and DCDC inverter, so that the electric supercharger and DCDC inverter can operate normally, and then the remaining power is provided to the BSG. The remaining power BSG uses the power limit P BSG ; BSG uses power limit P BSG Calculate the current limit value I of BSG BSG , and then through the BSG current limit I BSG The torque limit Tq corresponding to the BSG is calculated by reverse calculation and used for the limitation under the BSG power assist. The torque limit Tq of the BSG is sent to the BSG through the CAN network, so that the power consumption in the BSG power assist mode is within a certain limited range, thereby ensuring that the electric supercharger has sufficient power output. That is, the maximum torque that the BSG can output, the output torque of the BSG is controlled to be less than the torque limit Tq, and the energy of the battery provides energy to the BSG on the premise of ensuring the normal operation of the electric supercharger and the DCDC inverter; through the reasonable distribution of the energy of the mild hybrid system, since the electric supercharger has a higher efficiency in utilizing electric energy than the BSG, the performance of the electric supercharger is given priority, and then energy is provided to the BSG, thereby improving the transient response of the engine and the drivability of the vehicle;

[0088] By controlling the output torque of the BSG to be less than the torque limit Tq, the output torque of the BSG can be directly set. If the power consumed by the BSG is controlled to be less than the BSG power limit P BSG , the hardware of the BSG needs to be upgraded and adjusted. Compared with the energy allocation method of the mild hybrid system provided in this embodiment, by controlling the power consumed by the BSG to be less than the BSG power limit P BSG The method is difficult to operate and has high cost. The energy distribution method of the mild hybrid system provided in this embodiment achieves the effect of energy distribution from the software control perspective, without the need to add hardware for control. The method is simple, easy to operate and implement, and can reduce the additional cost caused by upgrading the hardware design.

[0089] At the same time, the energy distribution method of the mild hybrid system provided in this embodiment also avoids the risk of exceeding the safety upper limit of the mild hybrid system bus current when the electric supercharger and BSG are installed in the mild hybrid system at the same time; it improves the sustainability of the 48V mild hybrid system power-assist mode, and also ensures the safety of the 48V mild hybrid system, avoiding transient excessive current peaks that damage the battery of the 48V mild hybrid system. It solves the technical problem in the prior art that the battery energy in the mild hybrid system is not reasonably distributed, resulting in poor transient response of the engine and poor drivability of the vehicle, low engine power-assist efficiency, and the risk of exceeding the safety upper limit of the battery bus current.

[0090] like Figure 2 and Figure 3 As shown, an embodiment of the present invention further provides a control method for a mild hybrid system, the control method comprising:

[0091] Get the battery SOC;

[0092] The battery's SOC (State of Charge) is used to reflect the battery's remaining capacity. Its value is defined as the ratio of the remaining capacity to the battery capacity, usually expressed as a percentage. Its value range is 0 to 1. When SOC = 0, it means the battery is fully discharged, and when SOC = 1, it means the battery is fully charged.

[0093] The SOC of the battery can be obtained by the signal sent by the battery controller BMS module to the CAN network, that is, it can be directly obtained by reading the battery status.

[0094] comparing the SOC with a first preset ratio and a second preset ratio respectively;

[0095] Preferably, the first preset ratio is 30%; and the second preset ratio is 20%.

[0096] When the SOC is greater than the first preset ratio, the energy distribution method of the mild hybrid system is executed;

[0097] When the SOC is between the first preset ratio and the second preset ratio, the enabling of the BSG is interrupted and the electric supercharger is requested to be enabled;

[0098] The electric supercharger assist mode is still enabled normally under the emergency acceleration condition without any limit value, but the BSG assist mode is temporarily disabled and prohibited from being enabled. The 48V mild hybrid system assist mode is the electric supercharger assist alone.

[0099] When the SOC is less than the second preset ratio, enabling of the BSG and the electric supercharger is interrupted.

[0100] By using the control method of the mild hybrid system provided in the present embodiment, when there is a demand for rapid acceleration such as when the driver suddenly steps on the accelerator or overtakes, the SOC of the battery is obtained, and the remaining capacity of the battery can be actually considered to distribute the battery power supply. When the SOC exceeds 30%, it can be considered that the battery power is relatively sufficient, and the above-mentioned energy distribution method of the mild hybrid system can be directly executed to reasonably distribute the power of the 48V mild hybrid system. When the SOC is between 20% and 30%, it can be considered that the battery power is in a transitional stage, and only the more efficient electric supercharger request is considered to be enabled, that is, the electric supercharger works and the enabling of the BSG is interrupted, thereby saving the power of the 48V mild hybrid system; when the SOC is lower than 20%, the enabling of the BSG and the electric supercharger is interrupted to protect the battery of the mild hybrid system.

[0101] The control method of the mild hybrid system switches and distributes the energy of the mild hybrid system using different working modes according to the SOC of the battery, thereby avoiding excessive power consumption of the mild hybrid system and improving the sustainability of power supply of the mild hybrid system.

[0102] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0103] like Figure 4 As shown, the present embodiment further provides a mild hybrid system, the control method mild hybrid system includes an electronic control unit 100 and a battery 200, the battery 200 is electrically connected to the electric supercharger 300, the DCDC inverter 400 and the BSG500 respectively; the electronic control unit 100 is electrically connected to the battery 200, the electric supercharger 300, the DCDC inverter 400 and the BSG500 respectively; the electronic control unit 100 is electrically connected to the battery 200, the electric supercharger 300, the DCDC inverter 400 and the BSG500 respectively, and is communicatively connected through the vehicle body network CAN; the electronic control unit is electrically connected to the electronic control unit 100 to realize energy distribution between the electric supercharger and the BSG according to the above-mentioned energy distribution method of the mild hybrid system, or to control the working state of the electric supercharger and the BSG according to the above-mentioned control method of the mild hybrid system.

[0104] The present invention also provides a mild hybrid system, which gives priority to the performance of the electric supercharger 300 and then provides energy for the BSG500, thereby improving the transient response of the engine and the drivability of the vehicle. In addition, the mild hybrid system can switch and distribute the energy of the mild hybrid system in different working modes according to the SOC of the battery 200, thereby avoiding excessive power consumption of the mild hybrid system and improving the sustainability of the power supply of the mild hybrid system.

[0105] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0106] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0107] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0108] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0109] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or partly contributed to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0110] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An energy distribution method for a mild hybrid system, characterized in that: The energy distribution method comprises the following steps: Get the target power P of the electric supercharger ESC and the power P of the DCDC inverter DCDC ; The target power P ESC The power required for the normal operation of the electric supercharger; According to the target power P ESC and the power P DCDC , obtain the BSG power limit P BSG ; According to the power limit P BSG , get the current limit value I of BSG BSG ; According to the current limit I BSG , obtaining a torque limit value Tq of the BSG and controlling the output torque of the BSG to be less than the torque limit value Tq; The target power P of the electric supercharger is obtained ESC The steps include: Get the intake mass flow rate m of the electric supercharger air and the enthalpy change △h after the electric supercharger s ; The intake air mass flow rate m air and the enthalpy change Δh s Substitute into the first preset formula to calculate and obtain the target power P of the electric supercharger ESC ; Among them, the first preset formula is P ESC =m air ·Δh s .

2. The energy distribution method of a mild hybrid system according to claim 1, characterized in that: The step of controlling the output torque of the BSG to be less than the torque limit value Tq comprises: Multiply the torque limit value Tq by the correction coefficient map to obtain the corrected torque limit value Tq cap ; Control the output torque of BSG to be less than the corrected torque limit value Tq cap .

3. The energy distribution method of a mild hybrid system according to claim 1, characterized in that: The method of obtaining the intake mass flow rate m of the electric supercharger air The steps include: Get the constant pressure specific heat capacity C of air P , Intake air temperature upstream of the electric supercharger T in , a target boost pressure ratio PR and an air adiabatic index k for control of the electric supercharger; The constant pressure specific heat capacity of air C P , Intake air temperature upstream of the electric supercharger T in , the target boost pressure ratio PR and the air adiabatic index k of the electric supercharger for control are substituted into the second preset formula for calculation to obtain the intake mass flow rate m of the electric supercharger air ; The second preset formula is:

4. The energy distribution method of the mild hybrid system according to claim 3, characterized in that: The specific heat capacity of air at constant pressure C P It is 1.004 kJ / kg·k, and the air insulation index k is 1.

4.

5. The energy distribution method of a mild hybrid system according to claim 1, characterized in that: The power P of the DCDC inverter is obtained DCDC The steps include: Get the current I of the DCDC inverter DCDC and the voltage U of the DCDC inverter DCDC ; The current I of the DCDC inverter DCDC and the voltage U of the DCDC inverter DCDC Calculate and obtain the power P of the DCDC inverter DCDC .

6. The energy distribution method of a mild hybrid system according to claim 1, characterized in that: The current limit value I BSG , the steps of obtaining the torque limit value Tq of BSG include: The current limit I BSG Process according to preset rules to obtain the torque limit Tq of BSG.

7. A control method for a mild hybrid system, characterized in that: The control method comprises: Get the battery SOC; comparing the SOC with a first preset ratio and a second preset ratio respectively; When the SOC is greater than the first preset ratio, the energy distribution method of the mild hybrid system according to any one of claims 1 to 6 is executed; When the SOC is between the first preset ratio and the second preset ratio, the enabling of the BSG is interrupted and the electric supercharger is requested to be enabled; When the SOC is less than the second preset ratio, enabling of the BSG and the electric supercharger is interrupted.

8. The control method of the mild hybrid system according to claim 7, characterized in that: The first preset ratio is 30%; the second preset ratio is 20%.

9. A mild hybrid system, characterized in that: The mild hybrid system includes an electronic control unit and a battery, wherein the electronic control unit is electrically connected to the battery, the electric supercharger, the DCDC inverter and the BSG, respectively, and the battery is electrically connected to the electric supercharger, the DCDC inverter and the BSG, respectively; The electronic control unit realizes energy distribution between the electric supercharger and the BSG according to the energy distribution method of the mild hybrid system described in any one of claims 1 to 6, or controls the working state of the electric supercharger and the BSG according to the control method of the mild hybrid system described in claim 7 or 8.

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