A vehicle powertrain based on power function separation
By introducing a buffer energy storage unit into the vehicle power system to work in conjunction with the active power source, the power change rate can be identified or constrained in real time, thus solving the problem of discontinuous power distribution in the prior art and realizing the stable and flexible response of the vehicle power system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 贾理华
- Filing Date
- 2026-05-11
- Publication Date
- 2026-06-16
AI Technical Summary
Existing hybrid and range-extended power systems struggle to perform real-time, continuous power allocation based on power demand variation characteristics. The rate of change of the active power source output power is not explicitly constrained, and the intervention of auxiliary energy storage devices is a passive response. Consequently, the system's ability to identify and allocate power demand variation characteristics is limited.
By introducing a buffer energy storage unit into the vehicle power system to work in conjunction with the active power source, the rate of change in power demand or the rate of change in output power of the active power source can be identified in real time, thereby realizing real-time power distribution between the active power source and the buffer energy storage unit. The power control unit calculates and distributes the power demand according to the vehicle status to ensure dynamic response capability.
This achieves power balance in the vehicle's powertrain at any time, improves dynamic response, avoids switching between operating modes, and ensures the stability and flexibility of the vehicle's powertrain.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of vehicle powertrain and energy management technology, specifically to a vehicle powertrain system that performs real-time power distribution between the active power source and the buffer energy storage unit. Background Technology
[0002] In the field of vehicle powertrain systems, traditional vehicles typically use internal combustion engines as their primary power source. This type of powertrain system has high energy density and long driving range, but the engine system has a complex structure, significant mechanical losses, and certain limitations in power response speed and energy utilization efficiency.
[0003] With the development of electric drive technology, pure electric vehicles are gradually being widely used. Pure electric power systems have advantages such as relatively simple structure and fast power response, and can better meet the changing power demands of vehicles. However, the power battery system of pure electric vehicles needs to simultaneously meet two distinct performance requirements: one is energy storage, which means storing enough electrical energy to ensure driving range under reasonable volume and weight constraints; the other is power demand, which means providing transient high-power output during vehicle acceleration and hill climbing, and rapidly absorbing regenerative braking energy during braking. These two requirements are fundamentally contradictory at the cell design level, making it difficult for a single battery system to simultaneously achieve optimal performance in both energy storage and power dimensions.
[0004] To combine the advantages of internal combustion engines and electric drive systems, some vehicles employ hybrid or range-extended powertrains. These powertrains typically integrate an engine, an electric motor, and an energy storage system, distributing power among the different sources through control strategies. However, existing hybrid and range-extended powertrain control strategies generally trigger engine start-stop or mode switching based on the energy storage unit's state-of-charge threshold. The engine and energy storage unit alternately handle the vehicle's power demands, making it difficult for the system to continuously distribute power in real-time according to changing power requirements.
[0005] Existing technologies also include solutions that introduce auxiliary energy storage devices in addition to the main energy storage battery, with the aim of having the auxiliary energy storage device handle some of the transient power demand. However, the control strategies of existing solutions mostly adopt a state-of-charge threshold triggering method, the output power change rate of the main power source is not explicitly constrained, the intervention of the auxiliary energy storage device is a passive response rather than active management, and the system's ability to identify and allocate power demand change characteristics is limited.
[0006] Therefore, how to achieve real-time coordination between the active power source and the buffer energy storage unit by actively identifying the characteristics of power demand changes or directly constraining the rate of change of the output power of the active power source while ensuring the vehicle's power response capability is a problem that needs further research in the field of vehicle power systems. Summary of the Invention
[0007] In view of the above problems, embodiments of the present invention are proposed to provide a vehicle powertrain system that overcomes or at least partially solves the above problems.
[0008] According to one aspect of the present invention, a vehicle powertrain system is provided, the system comprising: The main power source, buffer energy storage unit, electric drive unit, and power control unit include: The active power source provides continuous power output to the vehicle's powertrain. During vehicle operation, the active power source operates continuously, fulfilling the low-rate-of-change power requirements necessary for vehicle operation. The buffer energy storage unit is used to provide or absorb power when the vehicle's power demand changes, to handle the transient changes in the vehicle's power demand, and to improve the dynamic response capability of the vehicle's power system. An electric drive unit is used to convert electrical energy into vehicle driving force to drive the vehicle. The electric drive unit may include a drive motor and corresponding power electronic devices. The power control unit is used to calculate the vehicle's power demand based on the vehicle's operating status and to perform real-time power distribution between the main power source and the buffer energy storage unit.
[0009] During vehicle operation, the main power source and the buffer energy storage unit work together in real time, with no switching between their operating modes. The main power source continuously handles the low-rate-of-change portion of the vehicle's power demand, while the buffer energy storage unit continuously handles the high-rate-of-change portion.
[0010] The vehicle powertrain system satisfies the following power balance relationship at any given time: P_req(t) = P_main(t) + P_buffer(t); Where: P_req(t) is the power demand of the vehicle at time t; P_main(t) is the power provided by the main power source at time t; P_buffer(t) represents the power provided or absorbed by the buffer energy storage unit at time t. A positive value indicates that the buffer energy storage unit outputs power to the system, while a negative value indicates that the buffer energy storage unit absorbs power from the system.
[0011] When the vehicle's power demand changes rapidly, the buffer energy storage unit compensates for the difference between the output power of the main power source and the vehicle's power demand by providing or absorbing transient power, thereby enabling the main power source to operate under relatively stable conditions and ensuring that the vehicle's power system has good dynamic response capabilities.
[0012] Implementation Method 1: Power Allocation Based on Power Demand Change Rate In an optional embodiment, the system identifies the changing characteristics of power demand by calculating the vehicle power demand change rate dP_req(t) / dt in real time, and allocates power between the main power source and the buffer energy storage unit according to the change rate. Here, R1 is a preset power change rate threshold used to distinguish between low and high change rate portions of the power demand.
[0013] When the rate of change of vehicle power demand satisfies dP_req(t) / dt ≥ R1, it indicates that the vehicle power demand is increasing rapidly. In this case, the main power source continuously outputs power according to the power command constrained by the rate of change, and the buffer energy storage unit compensates in real time for the difference between the vehicle power demand and the actual output power of the main power source, i.e., P_buffer(t) = P_req(t) - P_main(t), to ensure the vehicle's power response capability.
[0014] When the rate of change of vehicle power demand satisfies 0 ≤ dP_req(t) / dt < R1, it indicates that the vehicle power demand is increasing slowly. In this case, the main power source can directly follow the change in vehicle power demand, while the buffer energy storage unit makes auxiliary adjustments according to system needs.
[0015] When the rate of change of vehicle power demand satisfies dP_req(t) / dt < 0, it indicates that the vehicle power demand has decreased. In this case, the system can flexibly adjust the output power of the main power source according to the magnitude and duration of the demand decrease; when the SOC of the buffer energy storage unit has not reached its upper limit, it can absorb the surplus power of the system. The specific adjustment strategy can be designed by the implementer according to the actual operating conditions.
[0016] Implementation Method 2: Power Allocation Based on Constraints on the Rate of Change of Output Power of Active Power Source In another alternative embodiment, the system achieves power allocation by directly constraining the rate of change of the output power of the active power source. Specifically, the rate of increase of the output power of the active power source is limited: dP_main(t) / dt ≤ R2; R2 represents the maximum permissible rate of increase in the output power of the main power source. By limiting the rate of increase in the main power source's output power, the main power source provides the continuous power portion of the vehicle's power demand, while the rapidly changing portion of the vehicle's power demand is provided or absorbed by the buffer energy storage unit. The rate of increase in the main power source's output power is limited by R2, while the rate of decrease is not equally limited. During vehicle deceleration or braking, the main power source can quickly reduce its output power to fully utilize the energy recovery capability of the buffer energy storage unit.
[0017] The two implementation methods described above can also be used in combination to further improve the control accuracy and robustness of the system.
[0018] Energy State Management of Buffer Energy Storage Units In some implementations, the system can manage the energy state of the buffer energy storage unit through energy management strategies. The energy state of the buffer energy storage unit is characterized by its State of Charge (SOC). The system sets an operating SOC range for the buffer energy storage unit: SOC_lower ≤ SOC ≤ SOC_upper; Where SOC_lower is the lower limit of the SOC operating range, and SOC_upper is the upper limit of the SOC operating range. The system further sets a target SOC (SOC_target), and continuously adjusts the output power of the active power source according to the deviation between the SOC of the buffer energy storage unit and the target value during vehicle operation, so that the SOC of the buffer energy storage unit dynamically converges towards SOC_target. The above adjustment is carried out continuously, rather than waiting for the SOC to deviate to a certain threshold before triggering, thereby avoiding large fluctuations in the SOC of the buffer energy storage unit.
[0019] The SOC_target can be a single target value or a narrower target range. The essence of the system continuously adjusting based on the deviation between the SOC of the buffer energy storage unit and the target value or target range remains unchanged.
[0020] While continuously meeting the vehicle's power requirements, the main power source continuously adjusts the output power based on the deviation between the SOC of the buffer energy storage unit and the target value, so that the SOC of the buffer energy storage unit continuously tends towards the target value, thereby decoupling the continuous energy supply and transient power regulation functions.
[0021] The above description is merely an overview of the technical solutions of the embodiments of the present invention. In order to better understand the technical means of the embodiments of the present invention and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of the present invention more obvious and understandable, specific implementation methods of the embodiments of the present invention are described below.
[0022] Figure 1 Vehicle powertrain structure diagram Figure 2 Schematic diagram of power allocation control logic based on power demand change rate identification Figure 3 Schematic diagram of power distribution control logic based on the constraint of the output power change rate of the active power source. Figure 4 Schematic diagram of the convergence control logic for the charged state of the buffer energy storage unit. Detailed Implementation
[0023] Figure 1 A schematic diagram of a vehicle powertrain system according to an embodiment of the present invention is shown, as follows: Figure 1As shown, the system includes: a main power source 101, a buffer energy storage unit 102, a power control unit 103, and an electric drive unit 104.
[0024] The main power source 101 and the buffer energy storage unit 102 are connected to the vehicle power bus. The sum of their output power is converted into mechanical energy by the electric drive unit 104 to drive the vehicle. The power control unit 103 collects the vehicle power demand, the output power of the main power source 101 and the state of charge of the buffer energy storage unit 102 in real time, and sends power commands to the main power source 101 and the buffer energy storage unit 102 accordingly.
[0025] Example 1: Hybrid Scenario This embodiment takes a typical range-extended hybrid passenger vehicle as an example to illustrate the specific implementation method when the main power source 101 is an engine power generation unit.
[0026] The vehicle's powertrain system includes an engine generator unit, a buffer energy storage unit 102, an electric drive unit 104, and a power control unit 103. The engine generator unit uses a 1.2L naturally aspirated Atkinson cycle engine with a rated output power of 60kW, operating continuously during vehicle operation. The buffer energy storage unit 102 uses a high-rate power battery system with a capacity of 3kWh and a peak discharge rate of not less than 20C, with a target state of charge (SOC) set at 50% and an SOC operating range set between 40% and 60%. The electric drive unit 104 uses an 80kW permanent magnet synchronous motor mounted on the drive shaft.
[0027] The power control unit 103 continuously collects the driver's pedal signal and the load information of each system in the vehicle, and comprehensively calculates the total power demand of the vehicle P_req(t), including but not limited to drive demand, thermal management load and vehicle electrical system load, and maintains the following power relationship in real time: P_req(t) = P_main(t) + P_buffer(t); The power control unit 103 identifies the changing characteristics of power demand by calculating the rate of change of vehicle power demand dP_req(t) / dt, and accordingly allocates power between the engine power generation unit and the buffer energy storage unit 102. The rate of change threshold R1 is set to 3kW / s.
[0028] Example 2: Pure Electric Scenario This embodiment takes a typical pure electric passenger vehicle as an example to illustrate the specific implementation method when the main power source 101 is a power battery.
[0029] The vehicle powertrain system includes a power battery, a buffer energy storage unit 102, an electric drive unit 104, and a power control unit 103. The power battery is an 80kWh lithium iron phosphate battery system with a discharge rate limited to below 1C, continuously outputting electrical energy during vehicle operation to meet the continuous power requirements of vehicle operation. The buffer energy storage unit 102 uses a high-rate power battery system with a rated capacity of 5kWh and a peak discharge rate of not less than 20C, with a target state of charge (SOC) set at 50% and an SOC operating range set between 40% and 60%. The electric drive unit 104 uses a permanent magnet synchronous motor with a rated power of 120kW and a peak power of 160kW, mounted on the drive shaft.
[0030] The power control unit 103 continuously collects the driver's pedal signal and the load information of each system of the vehicle, calculates the total power demand of the vehicle P_req(t) in a comprehensive manner, and maintains the following power relationship in real time: P_req(t) = P_main(t) + P_buffer(t); The power control unit 103 identifies the changing characteristics of power demand by calculating the rate of change of vehicle power demand dP_req(t) / dt, and accordingly allocates power between the power battery and the buffer energy storage unit 102. The rate of change threshold R1 is set to 3kW / s.
[0031] Example 3: Power allocation scenario based on power demand change rate identification Based on Example 1 or 2, a vehicle acceleration and overtaking scenario using a power demand change rate identification mechanism is described.
[0032] When the driver rapidly depresses the accelerator pedal, the vehicle's power demand increases rapidly within approximately 0.5 seconds, with the rate of change of power demand dP_req(t) / dt being much greater than the threshold R1. Upon recognizing this high rate of change in demand, the power control unit 103 continuously tracks the increasing power demand at a limited rate of change, as instructed by the power control unit 103. The buffer energy storage unit 102 compensates in real time for the difference between the vehicle's power demand and the actual output power of the power source 101: P_buffer(t) = P_req(t) - P_main(t). Once the vehicle's power demand stabilizes, the main power source 101 gradually increases in line with the vehicle's power demand, and the compensation power of the buffer energy storage unit 102 decreases accordingly until the main power source 101 bears all the continuous power demand, and the compensation power of the buffer energy storage unit 102 approaches zero.
[0033] Example 4: Power Allocation Scenario Based on Output Power Change Rate Constraint of Active Power Source 101 Based on Embodiment 1 or 2, a vehicle acceleration and overtaking scenario employing a constraint mechanism on the rate of change of output power of the active power source 101 is described. The power control unit 103 directly imposes a constraint on the rate of increase of output power of the active power source 101: dP_main(t) / dt ≤ R2, where R2 is set to 5kW / s. When the driver rapidly depresses the accelerator pedal, the vehicle's power demand increases rapidly. The power control unit 103 directly issues a power command to the active power source 101, increasing at a rate not exceeding 5kW / s. The buffer energy storage unit 102 continuously compensates for the difference between the vehicle's power demand and the actual output power of the active power source 101 in real time. The rate of decrease of output power of the active power source 101 is not equally restricted by R2. During vehicle deceleration or braking, the active power source 101 can rapidly reduce its output power, and the buffer energy storage unit 102 recovers energy through regenerative braking.
[0034] Example 5: Slowly Changing Power Demand Scenario Based on Embodiment 1 or 2, a scenario of slow vehicle acceleration on an urban road is described. The driver slowly depresses the accelerator pedal, and the vehicle's power demand increases from 15kW to 27.5kW within 5 seconds, with a power demand change rate dP_req(t) / dt = 2.5kW / s, satisfying 0 ≤ dP_req(t) / dt < R1. After recognizing the low rate of demand change, the power control unit 103 directly follows the change in vehicle power demand, without requiring the buffer energy storage unit 102 to provide additional power. Simultaneously, the power control unit 103 detects that the SOC of the buffer energy storage unit 102 is 46%, lower than the target value of 50%. Utilizing this slow change window, the power control unit 103 instructs the power source 101 to output an additional 2kW to charge the buffer energy storage unit 102, gradually bringing the SOC back to near the target value.
[0035] Example 6: SOC Continuous Management Scenario Based on Embodiment 1 or 2, SOC management during long-distance cruising is described. The vehicle cruises on a highway with a constant power demand. The output power of the main power source 101 outputs a stable power according to the demand, and the SOC of the buffer energy storage unit 102 is maintained near the target value of 50%. After a period of driving in urban conditions, the SOC of the buffer energy storage unit 102 drops to 45%, deviating from the target value by 5 percentage points. The power control unit 103 continuously monitors the SOC deviation and continuously adjusts the output power of the main power source 101, providing additional charging power while maintaining the vehicle's power demand, so that the SOC gradually recovers to near the target value. This adjustment is continuous, rather than waiting for the SOC to drop to a certain threshold before triggering, thus avoiding large fluctuations in SOC.
Claims
1. A vehicle powertrain system, characterized in that, The system includes: The main power source is used to provide continuous power output to the vehicle; A buffer energy storage unit is used to handle the high-rate-of-change portion of the vehicle's power demand. An electric drive unit is used to convert electrical energy into mechanical energy to drive a vehicle; The power control unit is used to calculate the vehicle power demand P_req(t) and its rate of change dP_req(t) / dt in real time. When dP_req(t) / dt exceeds the preset threshold R1, the power output of the main power source continuously tracks the vehicle power demand at a rate not exceeding the preset rate of change. The buffer energy storage unit compensates for the difference in real time according to P_buffer(t) = P_req(t) - P_main(t), so that the system satisfies P_req(t) = P_main(t) + P_buffer(t) at any time. Where: P_req(t) is the vehicle power demand at time t; P_main(t) is the main power source output power at time t; P_buffer(t) is the power provided or absorbed by the buffer energy storage unit at time t, with positive values indicating discharge and negative values indicating charging.
2. A vehicle powertrain system, characterized in that, The system includes: The main power source is used to provide continuous power output to the vehicle; The buffer energy storage unit is used to handle the real-time difference between the output power of the main power source and the power demand of the vehicle. An electric drive unit is used to convert electrical energy into mechanical energy to drive a vehicle; The power control unit is used to constrain the rate of change of the output power of the main power source, such that dP_main(t) / dt ≤ R2, where R2 is the preset maximum allowable rate of increase, and the rate of decrease of the output power of the main power source is not subject to the same constraint; the buffer energy storage unit compensates for the difference in real time according to P_buffer(t) = P_req(t) - P_main(t), so that the system satisfies at any time: P_req(t) = P_main(t) + P_buffer(t); Where: P_req(t) is the vehicle power demand at time t; P_main(t) is the main power source output power at time t; P_buffer(t) is the power provided or absorbed by the buffer energy storage unit at time t, with positive values indicating discharge and negative values indicating charging.
3. The system according to claim 1 or 2, characterized in that, The power control unit continuously adjusts the output power of the main power source according to the deviation between the state of charge of the buffer energy storage unit and the target value, so that the state of charge of the buffer energy storage unit continuously converges towards the target value. The adjustment is performed continuously rather than waiting for the state of charge to deviate to the threshold before triggering.
4. The system according to claim 1 or 2, characterized in that, The buffer energy storage unit is a high-rate battery with a maximum discharge rate of not less than 5C.
5. The system according to claim 1 or 2, characterized in that, When the main power source is an engine power generation unit, the engine power generation unit converts fuel energy into electrical energy, and its engine continues to run mechanically during vehicle operation.
6. The system according to claim 1 or 2, characterized in that, The main power source is a power battery.
7. The system according to claims 1 and 2, characterized in that, The power control unit employs both a power demand change rate identification mechanism and a power source output power change rate constraint mechanism. The combination of these two mechanisms improves the system's control accuracy and robustness.