Dynamic adjusting method and system for generating efficiency of hybrid vehicle under low-temperature working condition

Abstract

The invention relates to the technical field of energy management of new energy vehicles, in particular to a method and system for dynamically adjusting the power generation efficiency of a hybrid vehicle under a low-temperature working condition. According to the method, the characteristic that the heat dissipation capacity is sufficient in the low-temperature environment is fully utilized, the power generation efficiency of the motor is dynamically adjusted, excessive mechanical energy is converted into heat to be dissipated instead of electric energy, and therefore on the premise that the output torque of the shaft end of the generator is not changed, the electric power input into a battery is rapidly reduced, and the risk of sudden reduction of driving power is effectively handled; and meanwhile, the average efficiency loss caused by continuous reservation is avoided.

Description

Technical Field

[0001] This invention relates to the field of energy management technology for new energy vehicles, and in particular to a method and system for dynamically adjusting the power generation efficiency of hybrid vehicles under low-temperature operating conditions. Background Technology

[0002] During operation, the electrical energy generated by the engine driving the generator is used partly to drive the electric motor and partly to charge the battery. The battery's charging capacity is significantly affected by temperature. In low-temperature winter environments, the maximum acceptable charging power of the battery decreases drastically to prevent lithium deposition, ensure safety, and extend battery life. Under low-temperature conditions, the reduction in the battery's maximum permissible charging power may cause the engine's power generation, even at normal levels, to easily approach or exceed this limit. When the driving power drops rapidly, due to the engine's lag in power response, there is a risk of power imbalance in the system, which may trigger engine protection or lead to battery overcharging.

[0003] Existing technologies typically employ a reserve strategy based on power difference, which involves actively reducing the generator power setting when the power generation is close to the battery's maximum allowable charging power, reserving some buffer capacity. However, in low-temperature scenarios, the battery's maximum allowable charging power is already very low, and continuous reserve will severely reduce power generation efficiency, causing the engine to operate more inefficiently and increasing fuel consumption.

[0004] On the other hand, in low-temperature environments, vehicle cooling systems have relatively sufficient capacity, and motors and electronic control systems have a large thermal tolerance margin. Current technologies have failed to effectively utilize this characteristic to resolve the aforementioned contradiction. Therefore, there is an urgent need for an optimized control strategy for low-temperature operating conditions to maximize power generation efficiency while ensuring system safety. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of existing technologies and provide a method and system for dynamically adjusting the power generation efficiency of hybrid vehicles under low-temperature conditions. This method fully utilizes the ample heat dissipation capacity of low-temperature environments, dynamically adjusting the motor's power generation efficiency to convert excess mechanical energy into heat dissipation rather than electrical energy. This rapidly reduces the input battery power without changing the generator shaft output torque, effectively addressing the risk of sudden drops in drive power while avoiding average efficiency losses caused by continuous reserve.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for dynamically adjusting the power generation efficiency of hybrid vehicles under low-temperature operating conditions includes the following steps: Step 1: Acquire vehicle operating status parameters in real time. These parameters include at least the maximum allowable charging power of the battery. Current generator power output Drive power Battery temperature and drive motor temperature ; Step 2: Based on the battery temperature Determine if the operating condition is at a low temperature; Step 3: Under low-temperature conditions, based on the difference in charging power margin Based on the trend of driving power change, the target power generation efficiency is dynamically determined. The target power generation efficiency Below the current optimal power generation efficiency And the target power generation efficiency With the difference in charging power margin The decrease is due to the reduction in power or the strengthening of the downward trend in driving power; Step 4: Control the generator to achieve the target power generation efficiency. Operation, by adjusting the motor shaft current and shaft current The allocation ratio, while maintaining the rate of change of mechanical torque of the output shaft within a preset range, increases the internal losses of the motor, converting excess mechanical energy into heat energy, so that the actual output electrical power meets the constraints. ; Step 5: Monitor the temperature of the drive motor. The target power generation efficiency is dynamically adjusted based on temperature constraints. The lower limit.

[0007] Preferably, the step of determining whether the battery is in a low-temperature operating condition based on battery temperature includes: First, the battery temperature With preset low temperature threshold Compare; Secondly, when When this occurs, it is determined that the system has entered the low-temperature efficiency adjustment mode; Finally, when At that time, the conventional power reservation control strategy is executed.

[0008] Preferably, the step of dynamically determining the target power generation efficiency includes: First, based on the aforementioned charging power margin difference Risk classification: First step, when At that time, the basic target efficiency ; The second step, when hour, Through Determined by linear interpolation between the preset intermediate efficiency value; The third step, when hour, ; Secondly, based on the rate of change of driving power Perform trend compensation: when At that time, according to the formula ; Further reduce target efficiency, among which These are calibration coefficients.

[0009] Preferably, the adjusting motor shaft current and The steps for determining the shaft current distribution ratio include: First, while maintaining the output electromagnetic torque Provided the rate of change is within a preset range, it increases towards the direction of weakening the magnetic field. shaft current The absolute value; Secondly, corresponding adjustments shaft current To compensate The effect of shaft current variation on torque; Finally, the stator current amplitude is made Increase, thereby increasing copper loss This reduces power generation efficiency.

[0010] Preferably, the step of dynamically adjusting the lower limit of the target power generation efficiency based on temperature constraints includes: First, calculate the lower limit of efficiency based on the current motor temperature: , in For calibration coefficients, and These are the lower and upper temperature limits, respectively; Secondly, the target power generation efficiency is limited to no less than the lower efficiency limit: .

[0011] Preferred options also include: When the battery heating system requests heating and is in an extremely low temperature condition At this time, the target power generation efficiency is further reduced, so that the extra heat generated by the generator is directionally transferred to the battery pack through the coolant circuit for battery preheating.

[0012] A system for dynamically adjusting the power generation efficiency of hybrid vehicles under low-temperature operating conditions includes: The status acquisition module is used to obtain the battery's maximum allowable charging power in real time. Current generator power output Drive power Battery temperature and drive motor temperature ; The operating condition judgment module is used to determine the battery temperature. Determine whether to enter the low-temperature efficiency adjustment mode; The efficiency decision module is used to determine the efficiency margin difference in low-temperature efficiency adjustment mode. Based on the trend of driving power change, the target power generation efficiency is dynamically determined. The target power generation efficiency Below optimal power generation efficiency ; The motor control module is used to adjust the motor's... shaft current and shaft current The allocation ratio is used to control the generator to achieve the target power generation efficiency. The system operates by converting excess mechanical energy into heat energy while maintaining the rate of change of mechanical torque within a preset range. The thermal management coordination module is used to monitor the temperature of the drive motor. And dynamically adjust the target power generation efficiency. The lower limit.

[0013] Preferably, the efficiency decision module includes: A risk assessment unit is used to assess the difference in charging power margin. Conduct risk classification and determine basic target efficiency. ; Trend compensation unit, used to adjust according to the rate of change of drive power efficiency for the basic objective Perform dynamic correction; A thermal constraint unit is used to adjust the temperature of the drive motor. Calculate the lower limit of efficiency and limit the target power generation efficiency. It shall not be lower than this lower limit.

[0014] Preferably, the motor control module is a permanent magnet synchronous generator controller, which adjusts the motor control module through a vector control algorithm. shaft current and shaft current The reference value ensures that the motor operates at the operating point corresponding to the target efficiency.

[0015] A vehicle controller includes a memory and a processor, the memory storing a computer program that, when executed by the processor, implements the method described above.

[0016] Compared with existing technologies, the beneficial effects of this invention are as follows: It proposes a detection approach based on deep fusion of spatiotemporal rheological features. The core of this approach lies in breaking through the limitations of single-dimensional feature analysis and establishing a vector verification relationship between "historical accumulated potential energy" and "instantaneous diffusion kinetic energy." Specifically, for slow and weak signals, this invention uses nonlinear accumulation to amplify weak brightness change trends, solving the problem of long-term signals being submerged in background noise. For physically isomorphic artifacts, this invention constructs a dual-domain gradient alignment verification model, forcing the historically accumulated gradient direction (potential energy) and the current edge growth vector (kinetic energy) to maintain physical coupling in the same direction, thereby eliminating artifacts such as shadows (with gradient but no growth) or water stain evaporation (negative growth direction) from a mechanistic perspective. For the problem of rigid sampling strategies, this invention employs a "one cause, multiple effects" feedback adjustment mechanism, using high-confidence judgment results to dynamically drive adaptive adjustment of the acquisition frequency, achieving intelligent collaboration between monitoring and evidence collection. Through this collaborative decision-making based on multi-dimensional information, a technological leap from "apparent detection" to "physical mechanism verification" is achieved. Attached Figure Description

[0017] Figure 1 This is a flowchart of the adaptive control method for motor power generation efficiency under low-temperature operating conditions according to the present invention; Figure 2 A schematic diagram of the decision-making logic for the target power generation efficiency. Detailed Implementation

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0020] Reference Figure 1 and Figure 2 The hybrid vehicle low-temperature power generation efficiency dynamic adjustment system provided by this invention mainly includes the following components: a status acquisition module, an operating condition judgment module, an efficiency decision module, a motor control module, and a thermal management coordination module. These modules interact and transmit signals via onboard networks such as a controller area network (CAN), jointly achieving adaptive adjustment of motor power generation efficiency under low-temperature conditions.

[0021] The status acquisition module is used to acquire vehicle operating status parameters in real time. First, it acquires the battery's maximum allowable charging power in real time through the battery management system. and battery temperature The maximum allowable charging power of a battery reflects the maximum charging power permitted under the current battery state, and its value is affected by the battery's state of charge and temperature. Taking a typical new energy vehicle power battery as an example, in... hour Possibly reach And below zero It may drop to the following. The battery core temperature is measured by temperature sensors arranged within the battery pack, typically using the maximum or average value of multiple cell temperatures as the determining factor. Secondly, the current power generation is collected by the generator controller. This power value is the actual electrical power output of the generator, measured by sensors on the DC bus side of the inverter. The measurement accuracy is typically required to be within ±0.5%. Within this range. Next, the current drive power is calculated via the vehicle controller. and its rate of change The driving power is calculated based on a combination of information including the driver's accelerator pedal opening, motor speed, and vehicle speed; the rate of change is determined by considering adjacent cycles. The numerical difference calculation reflects the trend of drive power variation. Finally, the motor temperature is collected by a drive motor temperature sensor. This temperature reflects the current thermal state of the drive motor and is used for thermal safety management.

[0022] Operating condition judgment module based on battery temperature With preset low temperature threshold A comparison is made to determine whether the vehicle is operating under low-temperature conditions. According to an embodiment of the present invention, a low-temperature threshold... Calibrated as .when When the time is right, it is determined to enter the low-temperature efficiency adjustment mode; when At that time, the conventional power reservation control strategy is executed.

[0023] In low-temperature efficiency adjustment mode, the efficiency decision module determines the efficiency based on the difference in charging power margin. Based on the trend of driving power change, the target power generation efficiency is dynamically determined. This module is built-in based on and drive power change rate The two-dimensional efficiency mapping table or calculation algorithm can quickly output the target efficiency value based on real-time operating conditions. The efficiency decision module further includes: a risk assessment unit, used to assess the charging power margin difference... Risk classification and determination of basic target efficiency; trend compensation unit, used to adjust based on the rate of change of drive power. Dynamically adjust the basic target efficiency; thermal constraint unit, used to adjust the efficiency based on the drive motor temperature. Calculate the lower limit of efficiency and restrict the target power generation efficiency to not be lower than this lower limit.

[0024] The motor control module determines the target power generation efficiency based on the output of the efficiency decision module. The command adjusts the control parameters of the generator. Specifically, it adjusts the d-axis current of the permanent magnet synchronous generator. and q-axis current The power distribution, while maintaining the output torque change rate within a preset range, increases internal motor losses, thereby reducing the actual output power. The motor control module is a permanent magnet synchronous generator controller, which adjusts the d-axis current through a vector control algorithm. and q-axis current The reference value ensures that the motor operates at the operating point corresponding to the target efficiency.

[0025] The thermal management coordination module monitors the drive motor temperature and dynamically adjusts the boundary conditions for efficiency decisions based on temperature constraints. This module sets a lower efficiency limit related to the drive motor temperature. ,when When it rises, The corresponding increase is made to ensure that the heat dissipation system can cope with the increased heat load and prevent the motor from overheating.

[0026] The hardware configuration of the adaptive control system for motor power generation efficiency described in this invention includes the following components: The vehicle controller, as the core control unit, is responsible for running the control algorithm of this invention. The vehicle controller communicates with other controllers via a controller area network (CAN), acquiring necessary signals and sending control commands. Internally, the vehicle controller integrates a microprocessor, memory, CAN controller, and other functional units, enabling it to implement complex control logic and algorithms. The processor in the vehicle controller typically uses a 32-bit microcontroller with a clock frequency between 100MHz and 200MHz, equipped with abundant communication interfaces and storage resources to meet the computational requirements of real-time control algorithms.

[0027] The battery management system is responsible for monitoring and managing battery status, including real-time estimation of battery state of charge and health, and calculation of the current maximum allowable charging power. The battery management system (BMS) reports this information to the vehicle controller via the controller area network. It collects the temperature of each cell using temperature sensors distributed throughout the battery pack and calculates the maximum allowable charging power at different temperatures based on the battery's charge-discharge characteristic curves. In low-temperature environments, the BMS significantly reduces... To prevent lithium deposition and ensure battery safety.

[0028] The generator controller controls the operation of the generator, including functions such as power generation regulation and efficiency control. The generator controller receives the target efficiency command from the vehicle controller, adjusts the current distribution to achieve efficiency regulation, and updates the current power generation... The information is then reported to the vehicle controller. The generator controller typically uses a three-phase full-bridge insulated-gate bipolar transistor or a silicon carbide power module, and has comprehensive overcurrent, overvoltage, and overtemperature protection functions.

[0029] The drive motor temperature sensor is installed near the drive motor housing or windings to collect motor temperature signals in real time and send the temperature data to the vehicle controller. The temperature sensor can be a thermocouple, a thermistor, or a digital temperature sensor. Different types of sensors can be selected based on the motor's installation location and the required temperature measurement accuracy.

[0030] The Controller Area Network (CAN) connects the aforementioned controllers and sensors, transmitting vehicle operating status parameters and control commands. CAN offers high reliability and real-time performance, making it suitable for automotive electronic control system applications. The CAN messages involved in this invention include: battery status messages reported by the battery management system, generator status messages reported by the generator controller, and control command messages issued by the vehicle controller.

[0031] This solution mainly involves upgrading the control software algorithm, without adding or changing the hardware, and is easy to implement on existing vehicle platforms.

[0032] Example 1: Efficiency is dynamically adjusted based on the lookup table method; Reference Figure 1 The method for dynamically adjusting the power generation efficiency of hybrid vehicles under low-temperature operating conditions provided by the present invention includes the following specific steps.

[0033] Step 1: Signal Acquisition and Initialization After the controller is powered on, it collects the following signals in real time through the controller's local area network and other vehicle networks: First, collect the maximum allowable charging power of the battery reported by the battery management system. and battery temperature The maximum allowable charging power of a battery reflects the maximum charging power permitted under the current battery state, and its value is affected by the battery's state of charge and temperature. Taking a typical new energy vehicle power battery as an example, in... hour Possibly reach And below zero It may drop to the following. The core temperature of the battery is measured by temperature sensors arranged inside the battery pack. Usually, the maximum or average value of multiple cell temperatures is selected as the basis for judgment.

[0034] Secondly, the current power generation reported by the generator controller is collected. This power value represents the actual electrical power output of the generator, measured by sensors on the DC bus side of the inverter. The accuracy of the generator power measurement directly affects the accuracy of efficiency control; typically, a measurement error within ±0.5% is required. Within.

[0035] Next, the current drive power calculated by the vehicle controller is collected. and its rate of change The driving power is calculated based on a combination of information including the driver's accelerator pedal opening, motor speed, and vehicle speed; the rate of change is determined by considering adjacent cycles. The numerical difference calculation reflects the trend of driving power change. It is an important input parameter of this invention, used to predict the risk of power imbalance.

[0036] Finally, the temperature measured by the drive motor temperature sensor is collected. This temperature reflects the current thermal state of the drive motor and is used for thermal safety management. Motor temperature sensors are typically installed near the motor stator windings and can quickly respond to motor temperature rises.

[0037] At the same time, the controller reads pre-calibrated parameters, including: low temperature threshold. Optimal power generation efficiency Minimum allowable efficiency Safe charging margin threshold Early warning charging margin threshold Dangerous charging margin threshold wait.

[0038] Step 2: Operating Condition Assessment The controller compares the battery temperature. With low temperature threshold .like If the condition is determined to be a normal temperature operating condition, the process jumps to the normal strategy execution step and executes the normal power reservation strategy. If the condition is low, the system is determined to be in a low-temperature operating condition, and the core efficiency adjustment strategy of this invention is executed to continue with subsequent steps.

[0039] Step 3: Calculate the charging margin and its changing trend The controller calculates the real-time charging margin difference. The calculation formula is: ; in, The maximum charging power currently allowed by the battery. This represents the generator's current actual power output. A positive value indicates sufficient charging margin, while a negative value indicates that the power generation has exceeded the battery's absorption capacity, posing a risk of overcharging. For example, when... , hour, This indicates that the power generation has exceeded the battery's absorption capacity. Measures need to be taken to reduce the actual input power of the battery.

[0040] At the same time, the controller calculates or obtains the rate of change of drive power. This parameter reflects the instantaneous changes in the driver's demand for driving power. When When this occurs, it indicates that the drive power is decreasing. In this situation, the balance between the generator's mechanical power input and the drive demand is disrupted, and the excess mechanical energy needs to be consumed through other means. For example, in an emergency braking scenario, the drive power may... From the inside Down to However, the engine power response is lagging, so the excess power generated by the generator needs to be converted into heat energy and consumed by reducing efficiency.

[0041] Step 4: Dynamically determine target power generation efficiency This is a key step in the present invention, see reference. Figure 2 The decision-making logic includes the following three levels: First, perform a basic risk assessment. Based on... The value determines the basic risk level, and the following thresholds are set: when At that time, the risk is low and the basic objective is efficiency. At this point, the power generation is far below the battery's absorption capacity, and the system operates at its optimal efficiency point, ensuring economic efficiency.

[0042] when At that time, the risk was moderate. Through Linear interpolation between the preset intermediate efficiency value and the actual efficiency value.

[0043] when At that time, the risk was relatively high. By the preset intermediate efficiency value and Linear interpolation between them.

[0044] when At that time, the risk was extremely high. At this point, the power generation capacity far exceeds the battery's absorption capacity, requiring a maximum reduction in efficiency to dissipate the excess power.

[0045] Among them, the preset intermediate efficiency value Usually taken and The arithmetic mean, or calibrated according to the motor's thermal characteristic curve: ; For example, when , hour, ;like , ,current ,but: ; The advantage of using linear interpolation is that it provides better charging margin. When continuously changing, the target efficiency A smooth transition is achieved to avoid generator torque shocks caused by abrupt changes.

[0046] The above thresholds can be calibrated and adjusted according to vehicle characteristics and battery properties.

[0047] Secondly, dynamic trend compensation is implemented. Based on the basic risk assessment, the rate of change of driving power is further considered. If... Then, based on the magnitude of its absolute value, for Further adjustments and reductions are made to address the instantaneous power surge caused by sudden drops in drive power. Compensation coefficient. The calculation formula is: ; in, This is a calibration coefficient, which can be adjusted based on actual test results, and is typically between 0.1 and 0.5. The target efficiency is then determined. The calculation formula is:

[0048] This compensation mechanism can respond in advance to a decline in drive power, avoiding the risk of power imbalance. For example, when , hour, This indicates a 3% reduction in efficiency. Efficiency adjustment is achieved through motor control, with a response speed in the millisecond range, far faster than the engine's power reduction response, effectively suppressing the instantaneous power surge caused by sudden drops in drive power.

[0049] Finally, thermal constraints are applied. This is based on the current motor temperature. Lower limit of computational efficiency This is to prevent the motor from overheating. The higher the temperature, The larger it is. The calculation formula is: ; in, This is the calibration factor, typically ranging from 0.1 to 0.3; The lower limit of temperature, This represents the upper limit of the temperature range. The final target efficiency value is: ; This thermal constraint mechanism ensures that the increased losses are within the capacity of the heat dissipation system.

[0050] Further explanation regarding the output shaft mechanical torque maintenance strategy: In step four, the rate of change within a preset range specifically refers to: Adjusting the d-axis current using a vector control algorithm and q-axis current The allocation ratio makes the generator Electromagnetic torque The rate of change is controlled within a preset range.

[0051] This preset range is usually set to within ±5% (i.e.) ), or the absolute deviation is controlled within ±2Nm, where This is the baseline torque value. The setting is based on the following: The engine and generator are connected via a mechanical shaft. A torque change rate exceeding 5% may cause torsional vibration in the transmission system or fluctuations in engine speed, affecting driving smoothness. Considering that the accuracy of current sensors is typically ±2%, and the controller's calculation error, setting the change rate threshold to ±5% can achieve a balance between control accuracy and response speed. When the torque change rate is controlled within ±5%, the corresponding q-axis current adjustment amount... The torque is relatively small and will not cause motor control saturation. In practice, the controller operates based on the torque equation: ; When the d-axis current is adjusted At that time, in order to maintain The compensation amount of the q-axis current when the rate of change is within the preset range. Calculate using the following formula: ; Or use a simplified approximation (when) When smaller): ; Through the above compensation, it is ensured that the rate of change of mechanical torque is always within the preset ±5% range during the efficiency adjustment process, which satisfies the power balance requirements and ensures the stability of the mechanical system.

[0052] Step 5: Perform motor efficiency adjustment The motor controller receives the target efficiency output from the efficiency decision module. After the command is given, the following control strategy will be executed: For permanent magnet synchronous generators, their output electromagnetic torque With q-axis current Proportional, that is: ; in, This represents the number of pole pairs of the motor. This refers to the permanent magnet flux linkage. For a typical 48-slot, 8-pole permanent magnet synchronous motor... , ,but and The proportionality coefficient is approximately .

[0053] To reduce power generation efficiency, it is necessary to maintain the same Under the premise of increasing the magnitude of the stator current, this is typically achieved by injecting a negative d-axis current. To achieve this. At the point of optimal efficiency, Typically very small or close to zero. For example, at the rated operating point, Possibly , for Stator current Approximately .

[0054] When efficiency reduction is required, the controller sets a negative d-axis current reference value. According to the mathematical model of the motor, in When changes occur, in order to maintain the same The q-axis current reference value needs to be slightly adjusted. The new current command will generate a larger stator current: ; For example, from Increase to To maintain the same torque, from Increase to approximately Then the stator current from Increase to Increased by approximately .

[0055] Increased stator current leads to increased copper losses in the motor. ; in, For a typical motor, the stator resistance is... Approximately Copper loss from approximately Increase to approximately Increased by approximately Meanwhile, iron loss It also increases with current harmonics. The formula for calculating power generation efficiency is: ; in, This refers to the mechanical angular velocity of the motor. Increasing the stator current amplitude increases copper and iron losses, thus affecting power generation efficiency. It then declined.

[0056] The controller implements the above-mentioned current distribution adjustment through a vector control algorithm, specifically including: a current loop proportional-integral controller, a coordinate transformation module, and a space vector pulse width modulation module.

[0057] Step Six: Power Balance and Thermal Effects Due to reduced power generation efficiency, the actual electrical power output to the DC bus decreases when the engine input mechanical power remains constant or is adjusted slowly. The calculation formula is: ; in, The mechanical power input to the generator. This is the adjusted power generation efficiency. For example, when... , When it drops from 0.92 to 0.70, from Down to Reduced .

[0058] The electrical power satisfies the following constraints: ; Right now This avoids the risk of battery overcharging. For example, when At that time, after adjustment This still exceeds the limit, and at this point, efficiency needs to be further reduced to... Only then can the constraints be satisfied.

[0059] At the same time, the reduced electrical power is converted into heat, which is carried away by the motor's cooling system. For example, , , Then the power converted into heat is This heat needs to be carried away by the coolant circulation. Due to the low temperature environment, the cooling system is fully capable of handling this additional heat load.

[0060] Step 7: Continuous Monitoring and Adjustment The controller returns to the signal acquisition step and continues the cycle for the next control period. When the battery temperature rises, it exits the low-temperature operating condition. ), or charging margin When it becomes very large, the target efficiency Automatically restore to Alternatively, a conventional reserve strategy can be implemented to end the temporary inefficient operating state. To ensure driving smoothness, the efficiency recovery process adopts a gradual approach, with the recovery range per cycle not exceeding a set value, thus avoiding the impact of sudden efficiency changes.

[0061] Step 8: Execution of Standard Strategies When under normal temperature conditions ( ), and execute the existing control strategy based on power reservation. The specific method is as follows: according to A reserved power value is obtained by looking up a table, and then the power generation command is reduced. This strategy is existing technology.

[0062] Example 2: Dynamic optimization of efficiency based on model predictive control; The difference between this embodiment and Embodiment 1 is that it uses a model predictive control algorithm instead of the lookup table method to achieve dynamic decision-making on the target power generation efficiency, which is suitable for driving scenarios with drastic changes in operating conditions and high nonlinearity.

[0063] Step 1: Establish a prediction model Construct a state-space model containing the following variables: state variables Control variables ; Disturbance variables The prediction time domain is set to... Control time domain .

[0064] The state equation can be expressed as:

[0065] in, , , The system matrix can be obtained through system identification or mechanism modeling.

[0066] Step 2: Rolling optimization of the objective function Define the cost function for:

[0067] The meanings of each item are as follows: the first item is to ensure charging safety and avoid overcharging; the second item is to maximize power generation efficiency; the third item is to constrain motor temperature; and the fourth item is to limit sudden changes in control quantities.

[0068] Constraints:

[0069]

[0070] The above constraints ensure that the control quantity varies within a reasonable range, avoiding excessive impact on the system.

[0071] Step 3: Real-time Solving and Execution In each control cycle, the vehicle controller solves the above quadratic programming problem to obtain the optimal control sequence. Only the first control variable is implemented. The state is resampled and optimized in the next cycle.

[0072] The advantage of model predictive control (MMCC) lies in its ability to anticipate future operating conditions using predictive models and adjust control strategies in advance. Compared to lookup table methods, MMCC can predict power demand changes over the next 10 cycles, adjusting efficiency ahead of time. This reduces the risk of exceeding charging power limits under continuous acceleration and deceleration conditions. And efficiency loss is reduced. This embodiment is suitable for high-end vehicles or applications with high control performance requirements.

[0073] Example 3: Thermal management collaborative strategies that combine battery heating requests; The difference between this embodiment and Embodiment 1 is that the power generation efficiency adjustment and the battery heating system are controlled in a coordinated manner at extremely low temperatures ( Under these conditions, the extra heat generated by the generator is directed to preheat the battery pack, enabling active management of energy flow.

[0074] Step 1: Identification of Extremely Low Temperature Operating Conditions when and At this point, the system is determined to have entered an extremely low temperature collaborative mode. In this mode, the battery's charging capacity is extremely limited, but heating is urgently needed to restore performance. For example, at sub-zero temperatures... In this environment, It may drop to ,and If no measures are taken, Excessive power will lead to battery overcharging.

[0075] Step 2: Decision on Directed Heat Distribution The controller calculates the total excess power. If the battery heating request flag is set, adjust the target efficiency. Not only based on It also needs to meet the following requirements:

[0076] in, The power required to heat the battery. For example, , , , , The required power dissipation is Corresponding efficiency .

[0077] Step 3: Cooling circuit switching control While the generator controller adjusts the current distribution to reduce efficiency, the thermal management controller switches the cooling circuit valves to redirect motor coolant into the battery pack heat exchanger. The specific process of the cooling circuit switching is as follows: First, the thermal management controller receives coordinated control commands from the vehicle controller, including the target coolant temperature and flow distribution.

[0078] Secondly, the thermal management controller controls the switching valve to switch the coolant flow direction from the motor to the battery pack heat exchanger and then to the radiator.

[0079] Finally, adjust the speed of the coolant pump to increase the flow of coolant through the battery pack and accelerate heat transfer.

[0080] Heat generated by the generator This heat is carried away by the coolant and transferred to the battery pack, thus preheating the battery.

[0081] Step 4: Exit Heating and Charging Synergistic Operation when rebounded to The above, or At this time, the system gradually returns to high-efficiency mode. The exit process uses a gradual approach to avoid adverse effects on the battery from sudden temperature changes. Specific steps include: First, gradually improve the efficiency of the target. The increase per cycle shall not exceed .

[0082] Secondly, gradually reduce the coolant flow rate to slow down the rate of battery temperature rise.

[0083] Finally, when and When the system returns to normal levels, it exits the cryogenic collaborative mode and resumes the normal control strategy.

[0084] At zero In this environment, compared to using a positive temperature coefficient thermistor alone to heat the battery, this embodiment utilizes generator waste heat, which can save approximately [amount missing] power consumption of the positive temperature coefficient thermistor. to Shorten battery preheating time This also solves the problem of limited charging power. This embodiment is particularly suitable for vehicles in cold northern regions or vehicles that need to be started frequently in low-temperature environments.

[0085] The generator used in this invention is a permanent magnet synchronous generator, and its mathematical model is the foundation for achieving efficiency control. In a stationary three-phase coordinate system, the voltage equation of the permanent magnet synchronous generator is:

[0086] in, The stator voltage vector, The stator current vector, For stator resistance, This is the stator flux linkage vector.

[0087] Through coordinate transformation, the equations in the three-phase stationary coordinate system can be converted into equations in the two-phase rotating coordinate system. In the dq rotating coordinate system:

[0088]

[0089] in, , For the d-axis and q-axis voltages, , For the d-axis and q-axis currents, , For d-axis and q-axis inductance, Electric angular velocity, It is a permanent magnet flux linkage.

[0090] The electromagnetic torque equation is:

[0091] When using maximum torque-to-current ratio control and There exists an optimal ratio that minimizes the stator current.

[0092] When efficiency needs to be reduced, the controller deviates from the maximum torque-to-current ratio trajectory by increasing... This increases the stator current amplitude, thereby increasing copper losses.

[0093] The implementation block diagram of the vector control algorithm mainly includes the following parts: The coordinate transformation module includes Clarke transform and Parke transform. Clarke transform converts a three-phase stationary coordinate system (ABC) into a two-phase stationary coordinate system (ABC). ):

[0094] The Parker transformation transforms two stationary coordinate systems ( Convert to a two-phase rotating coordinate system (dq):

[0095] The current loop proportional-integral controller adjusts the d-axis and q-axis currents separately:

[0096]

[0097] in, , This is the current reference value. , For proportional gain, , This refers to the integral gain. The parameters of the proportional-integral controller need to be tuned according to the motor characteristics to ensure good dynamic response and steady-state accuracy.

[0098] The space vector pulse width modulation module modulates the voltage vector. , The inverse conversion is converted into a three-phase pulse width modulation duty cycle to control the inverter's switching action. Space vector pulse width modulation has high voltage utilization and low harmonic content, and is a widely used modulation method in motor control.

[0099] The efficiency control strategy is as follows: when it is necessary to reduce efficiency, the efficiency decision module outputs the target power generation efficiency. The controller calculates the corresponding d-axis current reference value. This relationship can be obtained through offline calibration or online calculation.

[0100] During efficiency adjustments, it's necessary to maintain the generator output torque variation rate within a preset range to ensure mechanical matching between the engine and generator. This requires adjusting... At the same time, make corresponding adjustments To compensate for torque variations.

[0101] According to the torque equation, when change To maintain the same torque, adjustments are required. :

[0102] Alternatively, adjust directly based on the maximum torque-to-current ratio trajectory to maintain... constant:

[0103] in, The target stator current amplitude.

[0104] Through the above adjustments, while reducing efficiency, the output torque can be maintained at a basically constant level, thus meeting the mechanical matching requirements of the engine-generator system.

[0105] In hybrid vehicles, the electrical energy generated by the generator driven by the engine needs to be distributed to the drive motor and the battery. The basic relationship of power flow is:

[0106] in, This refers to the generator's output power. To drive the motor and consume power, Battery charging and discharging power ( Indicates charging. (Indicates discharge). Power is consumed by low-voltage accessories.

[0107] In power generation mode, Electrical energy flows to drive the motor and battery:

[0108] in, To input mechanical power into the engine, This refers to the generator efficiency.

[0109] The relationship between battery charging power and generator output power is as follows:

[0110] The maximum acceptable charging power of a battery is limited by temperature:

[0111] when In such cases, measures need to be taken to reduce the power input to the battery. This invention reduces electrical power output by converting excess mechanical energy into heat energy by reducing power generation efficiency, thereby satisfying the constraints.

[0112] Sudden drop in drive power is a major risk scenario under low-temperature conditions. When the driver suddenly releases the accelerator or presses the brake pedal, the drive power drops rapidly, but the power response of the engine and generator is delayed. Taking a typical hybrid vehicle as an example: the drive motor power response time is about 20 to 50 ms; the generator power response time is about 100 to 200 ms; and the engine power response time is about 300 to 500 ms.

[0113] In the instant of a sudden drop in drive power, if the power generation fails to adjust in time, the excess mechanical power will be converted into electrical energy. If the battery cannot absorb this electrical energy, it will cause the DC bus voltage to rise, potentially triggering overvoltage protection.

[0114] The solution of this invention is to reduce the electrical energy delivered to the battery by rapidly decreasing the power generation efficiency. This reduces the driving power at... From the inside Down to For example: In the initial state, , , After a sudden drop in drive power, Still , After intervention by this invention, It dropped to 0.50. Further reduce Up to 0.33, The constraints are satisfied.

[0115] The entire adjustment process is completed within 10 to 20 ms, which is much faster than the engine power response and effectively avoids power imbalance.

[0116] Reducing power generation efficiency means that some mechanical energy is not converted into electrical energy, but rather into heat energy. The amount of heat energy generated is:

[0117] For example, , , ,but This heat needs to be removed through a cooling system.

[0118] Generator cooling systems typically employ liquid cooling, where coolant flows through the generator casing to carry away heat. The cooling system's heat dissipation capacity is:

[0119] in, This refers to the coolant mass flow rate. For specific heat capacity, , These are the inlet and outlet temperatures of the coolant.

[0120] In low-temperature environments, the ambient temperature is low, radiator heat dissipation efficiency is high, and the cooling system has a larger heat dissipation margin. Taking a typical hybrid vehicle as an example: under normal operating conditions, the coolant flow rate is approximately... Temperature rise approximately Heat dissipation capacity is approximately In low-temperature environments, the coolant flow rate can be increased to [amount missing]. With the same temperature rise, the heat dissipation capacity is approximately .

[0121] Therefore, the cooling system can handle the extra heat generated by the invention in low-temperature environments, preventing the motor from overheating.

[0122] The temperature of the drive motor is the core monitoring parameter for thermal management in this invention. The temperature sensor typically uses a negative temperature coefficient thermistor, installed near the motor stator windings, enabling rapid response to changes in winding temperature. The temperature signal, after filtering and processing, is used for thermal safety management.

[0123] The rise in motor temperature is related to power loss and heat dissipation conditions:

[0124] in, This is the motor's heat capacity. When... When the temperature rises, it rises; conversely, when it falls, it falls.

[0125] The safe temperature limit for a motor is usually determined based on its insulation class. The maximum permissible temperature for commonly used Class H insulation is... Considering measurement errors and safety margins, the upper limit of temperature in actual control... The general setting is Temperature limit Set as , which serves as a reference point for thermal constraint calculations.

[0126] This invention sets a lower limit for dynamic efficiency related to motor temperature:

[0127] in, , , , .

[0128] when hour, ; when hour, ; when hour, .

[0129] When the motor temperature rises, the lower limit of efficiency increases accordingly, limiting further reduction in efficiency, thereby controlling the rate of heat generation and preventing the temperature from continuing to rise.

[0130] This invention incorporates multiple security protection mechanisms to ensure system security under abnormal conditions: Over-temperature protection: When Exceed At this time, force exit the low-efficiency mode and restore efficiency to normal. At the same time, it triggers the cooling system to operate at maximum power.

[0131] Overcharge protection: When the battery charging power is detected to continuously exceed the limit... After a certain period of time, the efficiency will be immediately reduced to the minimum allowable value, and an alarm signal will be sent to the battery management system.

[0132] Communication failure protection: When a communication failure in the controller's local area network leads to the loss of critical signals, the system enters a safe mode and controls the system according to the most conservative strategy.

[0133] Hardware fault protection: When the current sensor or temperature sensor fails, a redundant sensor or estimated value is used, and a fault alarm is triggered.

[0134] Based on the above embodiments, the main parameters and their recommended ranges involved in this invention are shown in the following table: Table 1: Main Parameters and Recommended Range

[0135] The parameter values ​​mentioned above are only preferred ranges. Specific values ​​need to be calibrated and optimized based on factors such as vehicle platform, motor characteristics, and battery characteristics. In actual development, extensive real-vehicle testing and simulation verification are required to determine the optimal parameter configuration.

[0136] Under low-temperature conditions, a scenario of sudden drop in drive power was simulated to verify whether the system can avoid battery overcharging by reducing power generation efficiency.

[0137] Test conditions: Ambient temperature below zero The battery's initial temperature was below zero. , Generator power Drive power in From the inside Down to .

[0138] Test results: After the system detected a sudden drop in drive power, Internally, the power generation efficiency will decrease from 0.92 to 0.40, and the output power will decrease from... Down to Just right Constraints are applied to control DC bus voltage fluctuations within positive and negative limits. Within the specified timeframe, the battery did not experience overcharging. Test results demonstrate that this invention effectively prevents the risk of battery overcharging under low-temperature conditions.

[0139] The overall efficiency of this invention and traditional reservation strategies at the same security level is compared.

[0140] Test conditions: Ambient temperature below zero Continuous urban driving conditions Hourly average drive power Average power generation .

[0141] Test results: The average power generation efficiency of the traditional reserved strategy is 0.78, and the fuel consumption increases by about 8%; the average power generation efficiency of the proposed solution is 0.86, and the fuel consumption increases by about 4%; the efficiency is improved by about 8 percentage points.

[0142] Test results show that by utilizing the low-temperature heat dissipation margin, the present invention reduces the efficiency loss caused by continuous reservation and significantly improves the system's economy.

[0143] Under prolonged low-temperature operation, the temperature of the drive motor was monitored to verify the effectiveness of the thermal constraint mechanism.

[0144] Test conditions: Ambient temperature below zero Continuous operation Hours, continuously maintaining a low-efficiency mode ( , ).

[0145] Test results: Motor temperature from Rise to After stabilization, the coolant temperature rises by approximately The cooling system can continuously dissipate heat. The heat output and temperature rise curve tend to stabilize. Test results show that the thermal confinement mechanism can effectively control the motor temperature within a safe range.

[0146] Measure the time delay from the detection of a drop in drive power to the completion of efficiency adjustment.

[0147] Test conditions: Drive power decreases by a step, rate of change .

[0148] Test results: After the control system detected the change, in One control cycle ( Efficiency calculations are completed within ) days, in the )th One control cycle ( The current loop adjustment is completed within 1 hour, with a total response time of approximately 100 minutes. The engine power response time is approximately... The response speed of this invention is more than 17 times faster than that of an engine.

[0149] Verify the battery heating effect under ultra-low temperature synergistic mode.

[0150] Test conditions: Ambient temperature below zero The battery's initial temperature was below zero. Positive temperature coefficient thermistor heating power Generator power .

[0151] Test results: When using a positive temperature coefficient thermistor alone, the battery temperature drops from below zero. Rise to It takes approximately 45 minutes; in the collaborative mode of this invention, the battery temperature drops from below zero. Rise to It takes about 32 minutes, reducing heating time by 29%; the positive temperature coefficient thermistor saves approximately [amount missing] power consumption. .

[0152] Test results show that the present invention can effectively utilize generator waste heat to accelerate battery preheating while reducing the energy consumption of positive temperature coefficient thermistors.

[0153] The above detailed embodiments describe the system architecture, method steps, hardware configuration, motor control principle, power balance mechanism, thermal management strategy and parameter range of the present invention, and demonstrate the technical solutions under different application scenarios through multiple embodiments.

[0154] The specific embodiments should be understood as descriptions of preferred embodiments of the present invention. Various modifications and equivalent substitutions can be made to the present invention without departing from the spirit and scope of the present invention, and all such modifications and equivalent substitutions fall within the protection scope of the present invention.

[0155] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for dynamically adjusting the power generation efficiency of hybrid vehicles under low-temperature operating conditions, characterized in that, Includes the following steps: Step 1: Acquire vehicle operating status parameters in real time. These parameters include at least the maximum allowable charging power of the battery. Current generator power output Drive power Battery temperature and drive motor temperature ; Step 2: Based on the battery temperature Determine if the operating condition is at a low temperature; Step 3: The controller calculates the real-time charging margin difference. The calculation formula is: Under low-temperature operating conditions, based on the difference in charging power margin Based on the trend of driving power change, the target power generation efficiency is dynamically determined. The target power generation efficiency Below the current optimal power generation efficiency And the target power generation efficiency With the difference in charging power margin The decrease is due to the reduction in power or the strengthening of the downward trend in driving power; Step 4: Control the generator to achieve the target power generation efficiency. Operation, by adjusting the motor shaft current and shaft current The allocation ratio, while maintaining the rate of change of mechanical torque of the output shaft within a preset range, increases the internal losses of the motor, converting excess mechanical energy into heat energy, so that the actual output electrical power meets the constraints. ; Step 5: Monitor the temperature of the drive motor. The target power generation efficiency is dynamically adjusted based on temperature constraints. The lower limit.

2. The method according to claim 1, characterized in that, The step of determining whether the battery is in a low-temperature operating condition based on battery temperature includes: First, the battery temperature With preset low temperature threshold Compare; Secondly, when When this occurs, it is determined that the system has entered the low-temperature efficiency adjustment mode; Finally, when At that time, the conventional power reservation control strategy is executed.

3. The method according to claim 1, characterized in that, The steps for dynamically determining the target power generation efficiency include: First, based on the aforementioned charging power margin difference Risk classification: First step, when At that time, the basic target efficiency ; The second step, when hour, Through Determined by linear interpolation between the preset intermediate efficiency value; The third step, when hour, ; Secondly, based on the rate of change of driving power Perform trend compensation: when At that time, according to the formula ； Further reduce target efficiency, among which These are calibration coefficients.

4. The method according to claim 1, characterized in that, The adjustment motor shaft current and The steps for determining the shaft current distribution ratio include: First, while maintaining the output electromagnetic torque Provided the rate of change is within a preset range, it increases towards the direction of weakening the magnetic field. shaft current The absolute value; Secondly, corresponding adjustments shaft current To compensate The effect of shaft current variation on torque; Finally, the stator current amplitude is made Increase, thereby increasing copper loss This reduces power generation efficiency.

5. The method according to claim 1, characterized in that, The step of dynamically adjusting the lower limit of the target power generation efficiency based on temperature constraints includes: First, calculate the lower limit of efficiency based on the current motor temperature: ， in For calibration coefficients, and These are the lower and upper temperature limits, respectively; Secondly, the target power generation efficiency is limited to no less than the lower efficiency limit: 。 6. The method according to claim 1, characterized in that, Also includes: When the battery heating system requests heating and is in an extremely low temperature condition At this time, the target power generation efficiency is further reduced, so that the extra heat generated by the generator is directionally transferred to the battery pack through the coolant circuit for battery preheating.

7. A dynamic adjustment system for power generation efficiency of hybrid vehicles under low-temperature operating conditions, characterized in that, include: The status acquisition module is used to obtain the battery's maximum allowable charging power in real time. Current generator power output Drive power Battery temperature and drive motor temperature ; The operating condition judgment module is used to determine the battery temperature. Determine whether to enter the low-temperature efficiency adjustment mode; The efficiency decision module is used to determine the efficiency margin difference in low-temperature efficiency adjustment mode. Based on the trend of driving power change, the target power generation efficiency is dynamically determined. The target power generation efficiency Below optimal power generation efficiency ; The motor control module is used to adjust the motor's... shaft current and shaft current The allocation ratio is used to control the generator to achieve the target power generation efficiency. The system operates by converting excess mechanical energy into heat energy while maintaining the rate of change of mechanical torque within a preset range. The thermal management coordination module is used to monitor the temperature of the drive motor. And dynamically adjust the target power generation efficiency. The lower limit.

8. The system according to claim 7, characterized in that, The efficiency decision module includes: A risk assessment unit is used to assess the difference in charging power margin. Conduct risk classification and determine basic target efficiency. ; Trend compensation unit, used to adjust according to the rate of change of drive power efficiency for the basic objective Perform dynamic correction; A thermal constraint unit is used to adjust the temperature of the drive motor. Calculate the lower limit of efficiency and limit the target power generation efficiency. It shall not be lower than this lower limit.

9. The system according to claim 7, characterized in that, The motor control module is a permanent magnet synchronous generator controller, which adjusts the motor control through a vector control algorithm. shaft current and shaft current The reference value ensures that the motor operates at the operating point corresponding to the target efficiency.

10. A vehicle controller, characterized in that, It includes a memory and a processor, the memory storing a computer program that, when executed by the processor, implements the method as described in any one of claims 1 to 6.

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