Low-temperature starting method for extended-range hybrid electric vehicle

Abstract

The invention relates to the technical field of extended-range hybrid commercial vehicles, and particularly discloses a low-temperature starting method for an extended-range hybrid vehicle. According to the physical structure of the vehicle, a power battery main loop, a driving system main loop and a range extending system main loop are physically connected with an integrated controller through high-voltage wire harnesses; the engine system is connected with the interior of the integrated controller through copper plates, and the engine system is further connected with a 24V starting system; in a whole vehicle energy balance project, the output power of a range extender is equal to the sum of the power of a driving system, the power of a high-voltage accessory and the power of a power battery; according to the whole vehicle control strategy, the working state of the whole vehicle is mainly limited by the charging and discharging characteristics of the power battery under the low-temperature condition, and therefore the whole vehicle control strategy is designed according to the characteristics of the power battery at different temperatures; through the design of a high-voltage structure and a low-voltage 24V starting system and in combination with a low-temperature control strategy of the whole vehicle, the working mode and state of the range extending system are adjusted, and low-temperature control and running of the vehicle are achieved.

Description

Technical Field

[0001] This invention relates to the field of range-extended hybrid commercial vehicle technology, specifically to a low-temperature start-up method for range-extended hybrid vehicles. Background Technology

[0002] Currently, CNG-powered electric vehicle (CNG) range-extended hybrid electric vehicles (REEVs) are experiencing unprecedented development opportunities, but they also face numerous challenges. For example, in low-temperature environments, battery performance deteriorates as temperature decreases, with battery capacity and output power significantly reduced, severely impacting vehicle start-up and operation. When the vehicle's battery system is in extremely cold conditions, it cannot meet the vehicle's discharge requirements, rendering the vehicle unable to move. Simultaneously, the range extender system cannot power the engine for starting and warm-up, failing to meet the vehicle's start-up and warm-up needs, thus affecting normal vehicle use.

[0003] Therefore, it is necessary to design a low-temperature start-up method for range-extended hybrid vehicles to solve the problem that the existing power battery system of range-extended hybrid commercial vehicles cannot drive the vehicle in low-temperature environments. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of this invention is to provide a low-temperature start-up method for range-extended hybrid vehicles.

[0006] The technical solution adopted by this invention to solve its technical problem is: a low-temperature start-up method for a range-extended hybrid vehicle, comprising the following steps:

[0007] S1. Vehicle physical structure: The main circuit of the power battery, the main circuit of the drive system, and the main circuit of the range extender system are physically connected to the integrated controller through a high-voltage wiring harness. Inside the integrated controller, they are interconnected through a copper plate. The range extender system is connected to the engine system, and the engine system is also connected to the 24V starting system.

[0008] S2. Vehicle starting scheme: When the power battery temperature is <A, the vehicle starts the engine through the 24V starting system; when the power battery temperature is >A, the vehicle starts the engine by driving the range extender system with power battery power.

[0009] S3. Post-start vehicle energy management: Vehicle energy balance engineering:

[0010] Range extender output power = drive system power + high voltage auxiliary component power - power battery power;

[0011] S4. Vehicle Control Strategy: When the vehicle is operating at low temperatures, it is mainly limited by the charging and discharging characteristics of the power battery. Therefore, a vehicle control strategy is designed to address the characteristics of the power battery at different temperatures.

[0012] Preferably, the threshold value A in step S2 is set based on the battery capacity, battery discharge map characteristics, and the power required by the range extender system to drive the engine. When the power battery temperature is <A, the power battery output power cannot meet the starting requirements of the vehicle engine system; when the power battery temperature is >A, the power battery output power meets the starting requirements of the vehicle engine system.

[0013] Preferably, the vehicle energy balance engineering in step S3 is expressed by the following formula:

[0014] P 增程器 =P 驱 +P 辅 -P 电 ;

[0015] P 辅 =P EHPS +P DCDC +P AC +P PTC +P ACM +P TMS ;

[0016] P 驱 The driving system power is calculated based on the current vehicle speed and throttle input to determine the driving intention.

[0017] P 电 The power of the battery is determined by looking up a table based on the current cell temperature and charge level;

[0018] P 辅 Real-time measurement and comparison of rated parameters for the power of high-voltage auxiliary components of the whole vehicle;

[0019] P AC Real-time measurement and comparison of rated parameters for high-voltage electric air conditioner power;

[0020] P DCDC Real-time measurement and comparison of rated parameters for the vehicle's DC-DC power;

[0021] P ACM Real-time measurement and comparison of rated parameters for high-pressure air pump power;

[0022] P EHPS Real-time measurement and comparison of rated parameters for the power of the high-voltage power steering motor;

[0023] P PTC For high-voltage electric heating power, real-time measurement + comparison of rated parameters;

[0024] P TMS For thermal management unit power, real-time measurement + comparison of rated parameters;

[0025] After the vehicle starts in low temperatures, due to the limitations of the power battery's charging and discharging characteristics, the current battery system only allows low-power discharge and prohibits charging.

[0026] Preferably, the characteristics of the power battery in step S4 are used to implement the vehicle control strategy. When the power battery temperature is extremely low, i.e., the battery temperature < K, the vehicle executes the following strategy a:

[0027] ① The vehicle can execute high-voltage commands, and the auxiliary components, including steering, DC, PTC, and TMS, must meet the working requirements;

[0028] ② Do not execute driver instructions;

[0029] ③ After the vehicle is connected to high voltage, the VCU determines the instantaneous discharge power by referring to a table based on the charging and discharging characteristics of the power battery. If it can meet the requirements for starting the engine, the engine is started through high voltage. If it cannot meet the requirements, the engine is started through the low voltage power supply of the 24V starting system. The engine first enters the idle warm-up mode.

[0030] ④ After the engine warms up, it enters a low-power power generation mode. During the start-up process, the engine is required to start at low temperatures, and the output power is stable. It operates in power generation or idling mode to avoid consuming electrical energy.

[0031] Preferably, the characteristics of the power battery in step S4 are used to implement the vehicle control strategy. When the power battery temperature is low, i.e., K < battery temperature < M, the vehicle executes the following strategy b:

[0032] ① The vehicle can execute high-voltage commands, and the auxiliary components, including steering, DC, PTC, and TMS, must meet the working requirements;

[0033] ② Execute drive commands and adjust the drive power in real time based on the current battery temperature and charging / discharging power;

[0034] ③ The engine starts in low-power power generation mode. After the output power stabilizes, the vehicle is driven according to the throttle opening and the battery compensation power.

[0035] ④ The engine output power is determined by the engine coolant temperature. If the coolant temperature is sufficient for driving, full power output can be performed. The minimum power is the power when the vehicle is stationary. The engine warm-up maintenance strategy is to maintain the power and stop the engine warm-up.

[0036] Preferably, the characteristics of the power battery in step S4 are used to implement the vehicle control strategy. When the cell temperature is suitable, i.e., M < battery temperature, the vehicle executes the following strategy c:

[0037] ① The vehicle can execute high-voltage commands, and the auxiliary components, including steering, DC, PTC, and TMS, must meet the working requirements;

[0038] ② Execute drive commands and adjust the drive power in real time based on the current battery temperature and charging / discharging power;

[0039] ③ The engine starts in normal power generation mode, and the vehicle is driven according to the throttle opening and battery compensation power.

[0040] Preferably, the temperature thresholds K, M, and N are selected based on the battery characteristics and the characteristics of the vehicle.

[0041] The present invention has the following beneficial effects:

[0042] The low-temperature starting method for range-extended hybrid vehicles designed in this invention achieves node overlap between the power battery, drive system, and power generation system in an integrated controller. The vehicle can start independently by driving the engine through the range extender, or it can start the engine through a 24V low-voltage power supply. Through the design of a high-voltage structure and a low-voltage 24V starting system, combined with the vehicle's low-temperature control strategy, this method is used to solve the current problem of vehicle adaptability to low-temperature environments. It mainly adjusts the working mode and status of the range extender system according to the current state of the vehicle to achieve low-temperature control and driving of the vehicle.

[0043] The low-temperature start-up method for range-extended hybrid vehicles designed in this invention proposes higher precision requirements for real-time power acquisition, accuracy analysis, and power prediction, ensuring that the vehicle warm-up and start-up operation can be carried out while the full battery system meets the charge and discharge map. Attached Figure Description

[0044] Figure 1 It is a model block diagram of the physical structure of a range-extended hybrid vehicle.

[0045] Figure 2 This is a flowchart of a low-temperature start-up method for range-extended hybrid vehicles. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0047] Example 1.

[0048] A method for low-temperature starting of a range-extended hybrid vehicle, the specific technical solution of which is as follows:

[0049] 1. Vehicle physical structure scheme.

[0050] The main circuit of the power battery, the main circuit of the drive system, and the main circuit of the range extender system are physically connected to the integrated controller via a high-voltage wiring harness. The range extender system is connected to the engine system, which in turn is connected to the 24V starting system. These components are interconnected within the integrated controller via a copper plate (sharing a common node). The energy flow of the entire vehicle can be arbitrarily controlled across these three components. The physical structure model is as follows: Figure 1 As shown.

[0051] 2. Vehicle starting procedure.

[0052] When the power battery temperature is below A, the power battery output power cannot meet the starting requirements of the vehicle's engine system. The vehicle starts the engine through the 24V starting system, and the entire vehicle warms up after starting. The starting energy flow is as follows: Figure 1 As shown in ③;

[0053] When the power battery temperature is greater than A, the power battery output power meets the starting requirements of the vehicle's engine system. The vehicle uses the power battery's electrical energy to drive the range extender system and start the engine; the starting energy flow is as follows: Figure 1 As shown in ①-② in the text;

[0054] The threshold value of temperature A is set based on the battery capacity, battery discharge map characteristics, and the power required by the range extender system to drive the engine.

[0055] 3. Vehicle energy management after startup.

[0056] Vehicle energy balance formula:

[0057] Range extender output power = drive system power + high voltage auxiliary component power - power battery power;

[0058] The energy balance engineering of the whole vehicle is expressed by the formula:

[0059] P 增程器 =P 驱 +P 辅 -P 电 ;

[0060] P 辅 =P EHPS +P DCDC +P AC +P PTC +P ACM +P TMS ;

[0061] P 驱 The driving system power is calculated based on the current vehicle speed and throttle input to determine the driving intention.

[0062] P 电 The power of the battery is determined by looking up a table based on the current cell temperature and charge level;

[0063] P 辅 Real-time measurement and comparison of rated parameters for the power of high-voltage auxiliary components of the whole vehicle;

[0064] P AC Real-time measurement and comparison of rated parameters for high-voltage electric air conditioner power;

[0065] P DCDC Real-time measurement and comparison of rated parameters for the vehicle's DC-DC power;

[0066] P ACM Real-time measurement and comparison of rated parameters for high-pressure air pump power;

[0067] P EHPS Real-time measurement and comparison of rated parameters for the power of the high-voltage power steering motor;

[0068] P PTC For high-voltage electric heating power, real-time measurement + comparison of rated parameters;

[0069] P TMS For thermal management unit power, real-time measurement + comparison of rated parameters;

[0070] After a vehicle starts in low temperatures, due to the limitations of the power battery's charging and discharging characteristics, the current battery system only allows low-power discharge and prohibits charging. To meet the battery's charging and discharging characteristics, the range extender output power must equal the drive system power plus the high-voltage auxiliary component power minus the power battery power. By real-time monitoring of the vehicle's power consumption and the battery's allowable charging and discharging power, the range extender system's power generation is dynamically controlled to ensure the vehicle remains in a basically balanced battery state and that the power battery's charging and discharging power is within the battery's required range.

[0071] The charging and discharging maps of the power battery are shown in Tables 1 and 2 below:

[0072] Table 1. Charging map of the power battery system.

[0073]

[0074] Table 2. Discharge map of power battery system.

[0075]

[0076] 4. Vehicle control strategy, such as Figure 2 As shown.

[0077] The vehicle's operation at low temperatures is mainly limited by the charging and discharging characteristics of the power battery. Therefore, a vehicle control strategy is designed to address the power battery characteristics at different temperatures.

[0078] 1) When the power battery temperature is extremely low, i.e., battery temperature < K, the vehicle will execute the following strategy a:

[0079] ① The vehicle can execute high-voltage commands, and auxiliary components including steering, DC, PTC, and TMS must meet the working requirements.

[0080] ② Do not execute driver instructions.

[0081] ③ After the vehicle is connected to high voltage, the VCU determines the instantaneous discharge power by referring to a table based on the charging and discharging characteristics of the power battery. If the power is sufficient to start the engine, the engine is started via high voltage; otherwise, it is started via 24V low voltage power. The engine first enters idle warm-up mode.

[0082] ④ After the engine warms up, it enters a low-power power generation mode, adhering to the engine's low-temperature start-up requirements during the start-up process. Output power is stable, operating in power generation or idling mode to avoid consuming electrical energy.

[0083] 2) When the power battery temperature is low, i.e., K < battery temperature < M, the vehicle operates according to strategy b as follows:

[0084] ① The vehicle can execute high-voltage commands, and auxiliary components including steering, DC, PTC, and TMS must meet the working requirements.

[0085] ② Execute drive commands and adjust the drive power in real time according to the current battery temperature and charging / discharging power.

[0086] ③ The engine starts in low-power power generation mode. After the output power stabilizes, the vehicle is driven according to the throttle opening and battery compensation power.

[0087] ④ The engine output power is used to determine the engine coolant temperature. If the coolant temperature is sufficient for driving, full power output can be performed (the minimum power is the power when the vehicle is stationary, and the engine warm-up maintenance strategy a power is used to stop the engine warm-up).

[0088] ⑤ Strategy b Vehicle driving state:

[0089] The power of the vehicle drive system is limited and adjusted linearly with the output power of the power battery (the lowest temperature of the battery) to ensure that the power battery does not overcharge or over-discharge.

[0090] Under normal circumstances: drive system power < power battery continuous discharge power + engine output power.

[0091] When the SOC (remaining battery charge) is less than 30%: drive system power < engine output power - battery continuous charging power (to generate small amounts of electricity from the battery to avoid the SOC being too low).

[0092] ⑥ Other modes.

[0093] When the battery temperature is ≤N, the EV mode will not be activated; at other temperatures, refer to the battery discharge map.

[0094] When the battery temperature is ≤N, the forced power generation mode will not be activated. At other temperatures, refer to the battery charging map.

[0095] 3) If the cell temperature is suitable, i.e., M < battery temperature, the vehicle will execute the following strategy c:

[0096] ① The vehicle can execute high-voltage commands, and auxiliary components including steering, DC, PTC, and TMS must meet the working requirements.

[0097] ② Execute drive commands and adjust the drive power in real time according to the current battery temperature and charging / discharging power.

[0098] ③ The engine starts in normal power generation mode, and the vehicle is driven according to the throttle opening and battery compensation power.

[0099] The temperature thresholds for K, M, and N are selected based on the characteristics of the battery and the vehicle.

[0100] This invention is not limited to the above-described embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.

[0101] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. A method for low-temperature starting of a range-extended hybrid vehicle, characterized in that, Includes the following steps: S1. Vehicle physical structure: The main circuit of the power battery, the main circuit of the drive system, and the main circuit of the range extender system are physically connected to the integrated controller through a high-voltage wiring harness. Inside the integrated controller, they are interconnected through a copper plate. The range extender system is connected to the engine system, and the engine system is also connected to the 24V starting system. S2. Vehicle starting scheme: When the power battery temperature is <A, the vehicle starts the engine through the 24V starting system; when the power battery temperature is >A, the vehicle starts the engine by driving the range extender system with power battery power. S3. Post-start vehicle energy management: Vehicle energy balance engineering: Range extender output power = drive system power + high voltage auxiliary component power - power battery power; S4. Vehicle Control Strategy: When the vehicle is operating at low temperatures, it is mainly limited by the charging and discharging characteristics of the power battery. Therefore, a vehicle control strategy is designed to address the characteristics of the power battery at different temperatures.

2. The low-temperature start-up method for a range-extended hybrid vehicle according to claim 1, characterized in that, The threshold value A in step S2 is set based on the battery capacity, battery discharge map characteristics, and the power required by the range extender system to drive the engine. When the power battery temperature is <A, the power battery output power cannot meet the starting requirements of the vehicle engine system; when the power battery temperature is >A, the power battery output power meets the starting requirements of the vehicle engine system.

3. The low-temperature start-up method for a range-extended hybrid vehicle according to claim 1, characterized in that, The vehicle energy balance engineering in step S3 is expressed by the following formula: P 增程器 =P 驱 +P 辅 -P 电 ; P 辅 =P EHPS +P DCDC +P AC +P PTC +P ACM +P TMS ; P 驱 The driving system power is calculated based on the current vehicle speed and throttle input to determine the driving intention. P 电 The power of the battery is determined by looking up a table based on the current cell temperature and charge level; P 辅 Real-time measurement and comparison of rated parameters for the power of high-voltage auxiliary components of the whole vehicle; P AC Real-time measurement and comparison of rated parameters for high-voltage electric air conditioner power; P DCDC Real-time measurement and comparison of rated parameters for the vehicle's DC-DC power; P ACM Real-time measurement and comparison of rated parameters for high-pressure air pump power; P EHPS Real-time measurement and comparison of rated parameters for the power of the high-voltage power steering motor; P PTC For high-voltage electric heating power, real-time measurement + comparison of rated parameters; P TMS For thermal management unit power, real-time measurement + comparison of rated parameters; After the vehicle starts in low temperatures, due to the limitations of the power battery's charging and discharging characteristics, the current battery system only allows low-power discharge and prohibits charging.

4. The low-temperature start-up method for a range-extended hybrid vehicle according to claim 1, characterized in that, The characteristics of the power battery in step S4 are used to implement the vehicle control strategy. When the power battery temperature is extremely low, i.e., the battery temperature is < K, the vehicle executes the following strategy a: ① The vehicle can execute high-voltage commands, and the auxiliary components, including steering, DC, PTC, and TMS, must meet the working requirements; ② Do not execute driver instructions; ③ After the vehicle is connected to high voltage, the VCU determines the instantaneous discharge power by referring to a table based on the charging and discharging characteristics of the power battery. If it can meet the requirements for starting the engine, the engine is started through high voltage. If it cannot meet the requirements, the engine is started through the low voltage power supply of the 24V starting system. The engine first enters the idle warm-up mode. ④ After the engine warms up, it enters a low-power power generation mode. During the start-up process, the engine is required to start at low temperatures, and the output power is stable. It operates in power generation or idling mode to avoid consuming electrical energy.

5. The low-temperature start-up method for a range-extended hybrid vehicle according to claim 4, characterized in that, The characteristics of the power battery in step S4 are used to implement the vehicle control strategy. When the power battery temperature is low, i.e., K < battery temperature < M, the vehicle executes the following strategy b: ① The vehicle can execute high-voltage commands, and the auxiliary components, including steering, DC, PTC, and TMS, must meet the working requirements; ② Execute drive commands and adjust the drive power in real time based on the current battery temperature and charging / discharging power; ③ The engine starts in low-power power generation mode. After the output power stabilizes, the vehicle is driven according to the throttle opening and the battery compensation power. ④ The engine output power is determined by the engine coolant temperature. If the coolant temperature is sufficient for driving, full power output can be performed. The minimum power is the power when the vehicle is stationary. The engine warm-up maintenance strategy is to maintain the power and stop the engine warm-up.

6. The low-temperature start-up method for a range-extended hybrid vehicle according to claim 5, characterized in that, In step S4, the characteristics of the power battery are used to implement the vehicle control strategy. When the cell temperature is suitable, i.e., M < battery temperature, the vehicle executes the following strategy c: ① The vehicle can execute high-voltage commands, and the auxiliary components, including steering, DC, PTC, and TMS, must meet the working requirements; ② Execute drive commands and adjust the drive power in real time based on the current battery temperature and charging / discharging power; ③ The engine starts in normal power generation mode, and the vehicle is driven according to the throttle opening and battery compensation power.

7. The low-temperature start-up method for a range-extended hybrid vehicle according to claim 6, characterized in that, The temperature thresholds K, M, and N are selected based on battery characteristics and vehicle characteristics.

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