Dual-motor heterogeneous electric drive system for electric heavy truck and control method of dual-motor heterogeneous electric drive system

Abstract

The invention relates to a dual-motor heterogeneous electric drive system for an electric heavy truck and a control method of the dual-motor heterogeneous electric drive system. The dual-motor heterogeneous electric drive system for the electric heavy truck comprises a motor A and a motor controller A. The motor controller A adopts an IGBT power module. A motor B is connected with a motor controller B, and the motor controller B adopts a SiC MOSFET power module; the input end of the power coupling device is respectively connected with the output shaft of the motor A and the output shaft of the motor B, and the power coupling device is used for coupling and outputting the power of the two motors; the power coupling device comprises a first speed reducer in transmission connection with the motor A and a second speed reducer in transmission connection with the motor B; according to the dual-motor heterogeneous electric drive system for the electric heavy truck and the control method of the dual-motor heterogeneous electric drive system, through cooperation of heterogeneous hardware and intelligent control, optimal balance of system efficiency and reliability is achieved at reasonable cost, and the contradiction between cost and endurance in the field of the electric heavy truck is solved. Meanwhile, the system has redundancy capacity, and the vehicle attendance rate is increased.

Description

Technical Field

[0001] This invention belongs to the field of motor drive technology, specifically relating to a dual-motor heterogeneous electric drive system for electric heavy trucks and its control method. Background Technology

[0002] Pure electric heavy-duty trucks (hereinafter referred to as "electric heavy-duty trucks") have become an important development direction in the commercial vehicle sector due to their significant advantages in energy conservation and emission reduction. As the core of electric heavy-duty trucks, the drive system's performance directly affects the vehicle's power, range, reliability, and cost. With the continuous expansion of electric heavy-duty truck application scenarios, such as heavy-load long-distance driving and mountain slopes, the market is placing more stringent demands on the drive system's power density, overall efficiency, and cost control.

[0003] Currently, mainstream electric drive solutions are mainly divided into two categories: The first type is the single-motor centralized drive scheme. This scheme typically uses a low-speed, high-torque permanent magnet synchronous motor (peak torque can reach over 3000 Nm) paired with a multi-speed mechanical gearbox. Its drawbacks are: to output extremely high torque, the motor and its controller require a large-size, multi-parallel power module design, resulting in a bulky, heavy, and costly system. The motor controller, needing to handle extremely high currents, faces challenges in current sharing, heat dissipation, and reliability due to the parallel connection of IGBT (Insulated Gate Bipolar Transistor) modules, leading to high system complexity and maintenance costs.

[0004] The second category is the dual-motor homogeneous drive scheme. To reduce the design and manufacturing costs of a single motor, this scheme uses two identical high-speed motors working in tandem. Based on the motor controller's technical approach, it can be further divided into two subcategories: First, using two identical IGBT controllers. This scheme has relatively controllable costs, but the high switching losses of IGBT devices at higher switching frequencies limit further improvements in system efficiency, affecting driving range. Second, using two identical silicon carbide (SiC) MOSFET controllers. SiC devices have the advantages of high frequency and high efficiency, which can significantly improve system efficiency. However, their current manufacturing cost is much higher than that of IGBTs, making the total cost of the dual-SiC scheme difficult for the market to accept. Furthermore, its efficiency advantage under high current conditions is not significant, and its long-term reliability data under the harsh conditions of commercial vehicles is still insufficient.

[0005] A deeper analysis reveals that IGBTs and SiC MOSFETs, as two mainstream power semiconductor devices, possess inherent and complementary differences in efficiency characteristics: IGBTs exhibit better conduction characteristics and mature reliability at medium to high currents and relatively low switching frequencies; while SiC MOSFETs demonstrate extremely low switching losses and a significant efficiency advantage at low to medium loads and high switching frequencies. However, existing homogeneous dual-motor solutions, whether employing dual IGBTs or dual SiC MOSFETs, fail to effectively utilize these differences, forcing the system to "accommodate" the efficiency limitations of a single device type under all operating conditions, thus failing to achieve optimal efficiency across the entire operating range. Furthermore, existing solutions often employ simple torque averaging or fixed-ratio distribution strategies, lacking intelligent dynamic control capabilities based on real-time operating conditions and a comprehensive system efficiency model, and thus unable to flexibly and precisely schedule the operating states of the two motors according to the actual load of the vehicle.

[0006] Therefore, how to design an innovative electric drive system architecture and its control method, which can cleverly integrate the technical advantages of IGBT and SiC at a reasonable overall cost, achieve the best balance between system efficiency, reliability and cost, and have intelligent energy management capabilities, has become a key technical problem that urgently needs to be solved in the field of electric heavy truck drive technology. Summary of the Invention

[0007] To address the problems of existing dual-motor homogeneous solutions failing to balance cost and efficiency, and single-motor solutions being costly and complex, the primary objective of this invention is to provide a dual-motor heterogeneous electric drive system for electric heavy-duty trucks. This system can achieve high-efficiency operation under all working conditions at a reasonable cost and possesses high reliability.

[0008] The present invention achieves the above objectives through the following technical solutions: The first aspect of this invention discloses a dual-motor heterogeneous electric drive system for electric heavy-duty trucks, the core concept of which lies in constructing an architecture that combines hardware heterogeneity with intelligent control collaboration. The system includes: Motor A and motor controller A, wherein the motor controller A adopts an IGBT power module that is low in cost, highly reliable and suitable for medium and high current conditions.

[0009] Motor B and motor controller B, wherein the motor controller B adopts a SiC MOSFET power module with good high-frequency characteristics and significant efficiency advantages under low and medium loads.

[0010] A power coupling device, whose input ends are connected to the output shafts of motor A and motor B respectively, is used to couple the power of the two motors for output. The key improvement of this device lies in its inclusion of a first reducer connected to motor A and a second reducer connected to motor B. The first reducer has a first reduction ratio, and the second reducer has a second reduction ratio, wherein the first reduction ratio is not equal to the second reduction ratio. This design allows the two motor systems (motor + reducer) to operate in a more optimal speed-torque range based on their respective efficiency characteristics and design priorities.

[0011] The vehicle control unit (VCU) is connected to the motor controller A and the motor controller B via signals. The VCU is configured to execute an intelligent torque distribution strategy: real-time acquisition of the vehicle's required torque; and dynamic selection of one of three driving modes based on the comparison result of the required torque with a preset threshold: (1) when the required torque is not greater than the first preset threshold (corresponding to low load conditions), the vehicle is driven by only the high-efficiency motor B (SiC driven) to maximize the efficiency advantage of SiC under light load; (2) when the required torque is greater than the first preset threshold but not greater than the second preset threshold (corresponding to medium-high load conditions), the motors A and B are driven together, and the optimal driving torque of the two motors is calculated and allocated in real time based on the pre-stored system efficiency model with the goal of minimizing the total system loss (i.e., the sum of the losses of the motor A subsystem and the motor B subsystem); (3) when the required torque is greater than the second preset threshold (corresponding to peak power demand), the motors A and B are both controlled to output their maximum available torque at their current speed to meet the vehicle's extreme power requirements.

[0012] A second aspect of the present invention provides a control method for the above-mentioned dual-motor heterogeneous electric drive system, comprising the following steps: Real-time acquisition of the vehicle's required torque and current vehicle speed (or motor speed); Determine the range to which the required torque belongs: a first range (not greater than a first preset threshold), a second range (greater than a first preset threshold and not greater than a second preset threshold), or a third range (greater than a second preset threshold). Execute the drive mode control command corresponding to the zone: If it is in the first zone, it enters the single motor drive mode and only motor B is activated; if it is in the second zone, it enters the hybrid drive mode and performs optimal torque distribution based on the system efficiency model; if it is in the third zone, it enters the peak power mode and both motors output at full power.

[0013] Furthermore, the system efficiency model is constructed based on bench tests of the first subsystem consisting of motor A and motor controller A, and the second subsystem consisting of motor B and motor controller B, respectively, to obtain their efficiency MAPs at different speeds and torques. Optimal torque allocation can be achieved by querying a pre-stored optimal allocation table (offline optimization result) with the required torque and speed as input, or by solving the optimization equation with the goal of minimizing total losses online through the VCU.

[0014] Furthermore, in pursuit of ultimate efficiency and functionality, this invention also includes the following optimized and extended features: a clutch can be added between the motor and the reducer to eliminate drag losses; the VCU can integrate predictive functions based on navigation or historical data to perform forward-looking torque distribution adjustments; motor A and motor B can adopt different types (such as permanent magnet synchronous and excitation synchronous) to form a deeper heterogeneity; and the operating parameters (such as nominal current and switching frequency) of motor controllers A and B are set differently according to their device characteristics.

[0015] The beneficial effects of this invention are as follows: This invention creatively combines a low-cost, high-reliability IGBT controller with a high-efficiency SiC controller in a heterogeneous manner, replacing the expensive dual-SiC solution or the inefficient dual-IGBT solution. By rationally allocating different load conditions to the advantageous devices (SiC for the high-efficiency region, IGBT for medium-to-high loads and providing redundancy), the system achieves a system overall efficiency close to that of the dual-SiC solution while having a total cost only slightly higher than that of the dual-IGBT solution. This fundamentally alleviates the core contradiction between "range" and "cost" in electric heavy-duty trucks, and has broad commercial prospects. This invention is not simply a matter of stacking hardware, but rather a deep collaboration between "differentiated reduction ratio design" and "intelligent torque distribution based on an efficiency model" software algorithm. The differentiated speed ratios allow the two motors to operate within their respective more efficient or suitable speed ranges; the intelligent control strategy adjusts the system's operating point in real time according to demand, placing it within the high-efficiency region of the comprehensive efficiency map. This combination of "hardware-oriented optimization" and "real-time software optimization" ensures that the system operates at its optimal or near-optimal efficiency under various conditions, from city cruising to heavy-load hill climbing, thereby significantly improving the vehicle's driving range. The system comprises two independent drive trains (motor A and controller A, motor B and controller B). If one train fails (e.g., a problem occurs with the SiC controller during its exploratory phase), the other (the mature IGBT system) can still independently drive the vehicle, providing a "limp-home" capability, significantly improving vehicle uptime and operational safety. This redundancy design is particularly suitable for the commercial heavy-duty truck sector, where reliability requirements are extremely high. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall scheme of the dual-motor heterogeneous electric drive system of the present invention.

[0017] Figure 2 This is a flowchart of the control method of the present invention.

[0018] Figure 3 This is a schematic diagram of the efficiency MAP of the present invention. Detailed Implementation

[0019] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0020] Example 1: In this example, motor A is a permanent magnet synchronous motor designed for high torque density. Its peak torque is 750 Nm, maximum speed is 10,000 rpm, peak power is 200 kW, and rated power is 100 kW. The design focus of this motor is to optimize torque output capability and cost control in the low-to-medium speed range. Motor controller A is a drive controller developed based on mature automotive-grade IGBT power modules (e.g., Fuji Electric X-series 1200V / 800A modules). Its nominal operating current is 800A, and the operating switching frequency is set to 8 kHz to balance control performance and switching losses. Motor B is a permanent magnet synchronous motor designed for high speed and a wide high-efficiency range. Its peak torque is 500 Nm, maximum speed is 18,000 rpm, peak power is 200 kW, and rated power is 150 kW. The design focus of this motor is to broaden the high-efficiency range and increase power density at high speeds. Motor controller B is a drive controller developed based on silicon carbide (SiC) MOSFET power modules (e.g., Semikron Danfoss DCM1000E33S3-ClaSSiC 1200V / 660A module). Its nominal operating current is 660A, and the operating switching frequency is set to 12 kHz to fully utilize the advantages of SiC devices, such as high frequency and low switching losses.

[0021] like Figure 1 As shown, the power coupling device employs a parallel-shaft gear-type power coupler. This device comprises two independent input shafts and a common output shaft.

[0022] The output shaft of motor A is connected to the intermediate shaft via a first set of gears (forming a first reducer). The reduction ratio iA (i.e., the first reduction ratio) of this set of gears is designed to be 3.0. This means that when the output shaft speed of the coupler is n... out At this time, the ideal operating speed of motor A is: nA = iA × n out.

[0023] The output shaft of motor B is connected to the same intermediate shaft via a second set of independent gear pairs (forming a second reducer). The reduction ratio iB (i.e., the second reduction ratio) of this set of gears is designed to be 2.0. Therefore, the ideal operating speed of motor B is: nB = iB × n out .

[0024] The design of iA ≠ iB is key to this embodiment. By using differentiated reduction ratios, it is possible to achieve the same overall vehicle speed (corresponding to the same n). out Under these conditions, motors A and B operate at different speeds. In this embodiment, by setting iA=3.0 and iB=2.0, the output speed n at the same coupler is achieved. out Below, the shaft end speed of motor B is (nB = i_B * n) out The speed at the shaft end of motor A is higher than the speed at the shaft end of motor A (nA = i_A * n). out Higher motor speeds require the controller to output higher frequency AC power, which allows the SiC MOSFET power module to leverage its low loss at high switching frequencies, enabling the motor B subsystem (SiC drive) to operate in a more efficient region.

[0025] In this embodiment, by setting iA = 3.0 and iB = 2.0, two key optimizations are achieved: (1) Torque contribution optimization: Motor A (IGBT drive) amplifies its high torque characteristics through a large reduction ratio iA, making it the main force of the system's high torque output (contributing about 69% of the total peak torque), which matches the characteristics of IGBT devices that are suitable for medium and high current and bear base load.

[0026] (2) Speed ​​range optimization: at the same vehicle speed (i.e., the same coupler output speed n) out Under these conditions, the shaft end speed of motor B is nB = iB × n out The shaft end speed nA = iA ×n is much lower than that of motor A. out This design enables: a. Motor A (matched with IGBT controller) operates in the low to medium speed range (e.g., when n out When nA = 7500 rpm, the IGBT controller operates efficiently at a moderate switching frequency (when nA = 2500 rpm).

[0027] b. Motor B (matched with SiC controller) operates in a lower speed range (nB=5000rpm in the same example), which allows the SiC controller to drive motor B at a higher switching frequency, thereby giving full play to its advantages of high frequency and low loss, and reserving sufficient high-efficiency speed working space for motor B (its peak speed can reach 18000rpm).

[0028] The two input forces converge on the gear on the intermediate shaft, and the coupled power is transmitted to the output shaft through the final reduction gear, thereby connecting to the vehicle's multi-speed transmission or direct drive axle. In this embodiment, the overall speed ratio of the coupler ranges from 2:1 to 5:1.

[0029] Vehicle Control Unit (VCU): It employs a multi-core microcontroller unit (MCU) that meets automotive-grade functional safety requirements (such as ISO 26262 ASIL-C). The VCU communicates in real time with motor controller A, motor controller B, and the vehicle's CAN network (to acquire signals such as accelerator pedal position, vehicle speed, gear position, and battery status) via a high-speed CAN (Controller Area Network) bus.

[0030] The control method in this embodiment has a clear flow and can be divided into two stages: system calibration (offline) and real-time control (online). The main online control flow can be found by referring to... Figure 2 .

[0031] On the dynamometer test bench, "Motor A, Motor Controller A, and First Reducer" were tested as a first drive subsystem, and "Motor B, Motor Controller B, and Second Reducer" were tested as a second drive subsystem. Under different input speeds (corresponding to nA or nB at different vehicle speeds), different output torques, and different DC bus voltages, the input electrical power and output mechanical power of each subsystem were accurately measured, thereby generating a complete and high-precision efficiency MAP (e.g., ...). Figure 3 (Schematic diagram of medium efficiency MAP).

[0032] Based on the efficiency MAP diagrams of the two subsystems mentioned above, a system overall efficiency model is established. For a given vehicle state (current vehicle speed V, corresponding to a determined coupler output shaft speed n), out And the total required torque Treq), the speeds of the two motors are nA = iA × n out and nB = iB × n out The overall system efficiency η total It is a function of the torque TA of motor A and the torque TB of motor B (satisfying TA + TB = Treq): η total(TA, TB) = [Output Power] / [Input Power of Subsystem A (TA, nA) + Input Power of Subsystem B (TB, nB)] In practice, to facilitate controller operations, optimization is often aimed at minimizing the total system loss, which is mathematically equivalent to maximizing the total efficiency.

[0033] Generate a three-dimensional optimal allocation table (lookup table method): For all possible operating points (covering n) out Based on the aforementioned model, and using optimization algorithms (such as traversal search or the Lagrange multiplier method) for offline calculation, the optimal torque distribution pair (TAopt, TBopt) that minimizes the total system loss is solved. The results are stored as a three-dimensional lookup table (LUT), with the inputs being: demand torque Treq, vehicle speed V (or n...). out The outputs are: battery voltage Udc; optimal target torque TAopt for motor A and optimal target torque TBopt for motor B. This table is pre-loaded into the VCU's Flash memory.

[0034] Drive mode threshold calibration: The first preset threshold T1 (single / dual mode switching threshold) is calibrated as 30% of the system's total peak torque capacity (750Nm * 3.0 + 500Nm * 2.0 = 3250Nm), i.e., T1 = 975Nm. Operating conditions below this threshold (such as city cruising and low-speed driving) typically correspond to low loads, where the SiC-driven motor B operates at its highest efficiency when working alone.

[0035] The second preset threshold T2 (peak power trigger threshold) is calibrated to 70% of the system's total peak torque capacity, i.e., T2 = 2275 Nm. When the required torque exceeds this value, it indicates that the vehicle needs to accelerate at full power or climb steep hills, and the system enters peak power mode.

[0036] During the real-time control phase (decision making and execution during vehicle operation), the VCU performs the following steps within each control cycle (e.g., 10ms): Step S100: Data acquisition and processing.

[0037] The VCU collects and processes the following signals in real time: accelerator pedal opening and rate of change (analyzed as driver-demanded torque Treq), current vehicle speed (converted to coupler output shaft speed n). out ), current gear position of the transmission, current voltage and available power of the power battery, and temperature of motor A / B and controller A / B.

[0038] Step S200: Driving mode decision.

[0039] Compare the processed real-time required torque \(T_{req}\) with the calibrated thresholds \(T_1\) and \(T_2\), and decide to enter one of the following three driving modes: If \(T_{req}\leq T_1\) (975 Nm), enter the "Single SiC Driving Mode".

[0040] If \(T_1\) (975 Nm) < \(T_{req}\leq T_2\) (2275 Nm), enter the "Hybrid Driving Mode".

[0041] If \(T_{req}>T_2\) (2275 Nm), enter the "Peak Power Mode".

[0042] Step S300: Patterned Torque Allocation and Execution.

[0043] Single SiC Driving Mode (S310): The VCU sends a target torque command to Motor Controller B, causing Motor B to output torque \(T_B = T_{req}\). At the same time, a zero torque command is sent to Motor Controller A, and Motor A is in an idling standby state. In this mode, the system makes full use of the high efficiency advantage of the SiC controller under medium and low loads.

[0044] Hybrid Driving Mode (S320): The VCU takes the current vehicle speed \(V\) (or \(n\) out ), the total required torque \(T_{req}\), and the battery voltage \(U_{dc}\) as inputs, queries the pre-stored three-dimensional optimal allocation table (LUT), and directly obtains the target torques \(T_{Aopt}\) and \(T_{Bopt}\) that minimize the total system losses under the current working conditions.

[0045] The VCU then sends commands to Motor Controller A and B respectively, controlling Motor A to output \(T_{Aopt}\) and Motor B to output \(T_{Bopt}\). This mode achieves the global efficiency optimization of the coordinated operation of the two motors.

[0046] (Alternative implementation method: Online optimization method. Instead of looking up the table, the VCU can also solve the optimization problem online based on the real-time collected speed, voltage, and current, combined with the stored motor loss equation, and calculate the optimal allocation in real time. This method is more flexible but has a larger computational load.) Peak Power Mode (S330): The VCU queries the peak torque capacity curve of the motor itself according to the current speeds (\(n_A, n_B\)) and temperature states of each motor, and determines the maximum available torques \(T_{Amax}\) and \(T_{Bmax}\) that can be safely output at its current speed.

[0047] Subsequently, the VCU instructs motor A to output TAmax and motor B to output TBmax. At this point, the total output torque of the system may exceed Treq, and the VCU or the motor controller will impose internal limits to ensure rapid power response without exceeding mechanical limits.

[0048] Step S400: Fault handling and redundancy protection.

[0049] The VCU continuously monitors the status of both subsystems. If a serious fault (such as overcurrent, overtemperature, or communication loss) is detected in either subsystem (e.g., motor controller B (SiC)), it immediately enters limp-home mode. If the fault occurs in the "single SiC drive mode", the VCU will immediately attempt to switch to the "single IGBT drive mode" where motor A is driven alone.

[0050] If the fault occurs in the dual-motor operating mode, the VCU disconnects the faulty subsystem and instructs the other healthy subsystem to continue driving the vehicle at its maximum capacity to ensure that the vehicle can drive away safely.

[0051] Example 2, based on Example 1, integrates a first electromagnetic clutch (CLA) between the output shaft of motor A and the input gear of the first reducer. This clutch is normally open, meaning it disengages when power is off and engages when power is on. Similarly, a second electromagnetic clutch (CLB) with the same type and characteristics as the first electromagnetic clutch is integrated between the output shaft of motor B and the input gear of the second reducer. These two clutches are independently controlled by the VCU through a newly added clutch drive module. The drive module receives commands from the VCU and outputs corresponding current to control the engagement and disengagement of the clutches.

[0052] The control flow of this embodiment adds collaborative control logic for the clutch in the real-time control loop of the core embodiment and optimizes the fault handling strategy.

[0053] Clutch coordination control in normal operating mode (integrated into all S300 modes): When entering "Single SiC Drive Mode" (S310): The VCU first sends a command to the clutch drive module to control the second electromagnetic clutch (CLB) to close, ensuring that the power transmission path of motor B is unobstructed.

[0054] Subsequently, the VCU sends a torque command TB = Treq to the motor controller B to drive the vehicle.

[0055] Simultaneously, the VCU ensures that the first electromagnetic clutch (CLA) remains disengaged and sends a zero-torque command to the motor controller A. This completely decouples motor A and its connected first reducer gear set mechanically. At this point, motor A does not rotate with the vehicle's transmission system, thus completely avoiding "dragging losses" such as gear churning losses, internal motor iron losses, and wind losses.

[0056] When entering "Hybrid Drive Mode" (S320) or "Peak Power Mode" (S330): The VCU controls the simultaneous engagement of the first electromagnetic clutch (CLA) and the second electromagnetic clutch (CLB) to establish a complete dual power flow.

[0057] The subsequent torque distribution and execution logic are exactly the same as in the core implementation.

[0058] Timing during mode switching: When switching modes (such as switching from single SiC mode to hybrid mode), the VCU will first control the clutch of the motor to be added to close. After the clutch status feedback confirms engagement, the torque command will be applied to the motor to ensure smooth shifting and avoid shock.

[0059] Enhanced "limp home" strategy under fault conditions: The VCU continuously monitors the health status of both subsystems. When either subsystem is detected (e.g., the motor controller B (SiC) reports an unrecoverable fault), the following enhancement strategy is executed: Step 1 (Rapid Isolation): The VCU immediately sends a zero-torque command to the motor controller corresponding to the faulty subsystem and commands its corresponding clutch (here, CLB) to disengage rapidly. This achieves both physical and electrical isolation of the faulty branch within milliseconds.

[0060] Step 2 (Mode Switching): The vehicle then enters the "Single IGBT Drive Mode" where it is driven solely by the health subsystem (Motor A in this case).

[0061] Step 3 (Smooth Driving): Since the faulty branch (motor B and the second reducer) has completely disengaged from the drivetrain, it will not generate any reverse drag torque or rotational inertia. Therefore, the healthy branch (motor A) can drive the vehicle smoothly and efficiently, achieving true "drag-free limp driving," significantly improving driving smoothness, safety, and drivable distance in fault mode.

[0062] By introducing a clutch, in "single SiC drive mode," it is expected to eliminate approximately 2-5 kW of parasitic drag loss (the specific value depends on vehicle speed and lubricant characteristics), which will further reduce the vehicle's energy consumption in urban conditions by approximately 1.5-3%. At the same time, fault isolation capability is significantly improved.

[0063] Example 3: This example performs in-depth optimization at the software algorithm level of the core example. By integrating predictive control based on navigation information, it achieves a leap from optimal instantaneous efficiency to optimal travel energy consumption.

[0064] The communication interface of the vehicle control unit (VCU) is expanded to connect with the vehicle's intelligent connected terminal (T-Box) or advanced driver assistance system (ADAS) domain controller via in-vehicle Ethernet or high-speed CAN FD bus, thereby enabling real-time acquisition of electronic horizon data containing future path information. This data includes at least information such as gradient, curvature, speed limits, and traffic events for the path over the next few kilometers (e.g., 3-5 kilometers).

[0065] This embodiment embeds a "predictive energy management module" running in the VCU within the control flow of the core embodiment. This module takes the aforementioned electronic horizon data as input, and its workflow is as follows: Step P100: Calculate the predicted load.

[0066] Starting from the current vehicle position, the VCU combines vehicle parameters such as mass (including load), drag coefficient, and rolling resistance coefficient, as well as the slope curve θ(s) and speed limit curve vlim(s) of the future path (where s is the distance), and uses the vehicle's longitudinal dynamics model to predict the required torque sequence Treqpred(k) for the vehicle to track the expected speed curve within a future time domain (such as the next 60 seconds or the corresponding distance), k=1,2,...,N, where k represents the k-th prediction step in the future.

[0067] Step P200: Proactive torque distribution optimization.

[0068] At the torque distribution decision point in the "hybrid drive mode" (S320) of the core embodiment, the VCU not only bases the current (n out The query (Treq) retrieves the most efficient table (resulting in the basic allocation values ​​TAbase and TBbase), and also incorporates predictive information for optimization. Optimization objective: To minimize the system's total energy consumption from the current moment until the end of the prediction time domain, not just to maximize instantaneous efficiency. This is a finite-time domain optimal control problem.

[0069] Solution method: Online rolling optimization is performed using the Model Predictive Control (MPC) framework.

[0070] Predictive model: A simplified system power consumption model built using a motor MAP diagram.

[0071] Optimization variables: The torque distribution sequence of motors A and B in the next N steps {TA(k), TB(k)}.

[0072] Constraints include: total torque meeting predicted demand (TA(k)+TB(k)=Treqpred(k)), motor torque and speed not exceeding limits, and battery power limitations.

[0073] Solution: In each control cycle, the VCU solves the optimization problem to obtain the future torque distribution sequence, but only the distribution results TAopt(1) and TBopt(1) from the first step are issued and executed as the current command. In the next cycle, the prediction time domain is updated on a rolling basis, and the solution is solved again.

[0074] Scenario A (Preloading): A long uphill climb is predicted in 30 seconds (Treqpred continuously increases). The MPC optimizer may instruct motor A (IGBT) to bear slightly higher torque than the instantaneous efficiency optimum at the current moment, thereby relatively reducing the load on motor B (SiC) and causing its operating point to move to a higher efficiency zone earlier. In this way, when the vehicle actually enters the climb, the SiC subsystem still has the margin to maintain high efficiency, while the IGBT subsystem has "warmed up" in advance and shared more load, resulting in lower overall energy consumption.

[0075] Scenario B (Pre-optimized cruise): A long downhill slope is predicted ahead. The MPC optimizer may reduce the total torque demand in advance before the crest of the slope and optimize its allocation to cool the battery or motor, preparing for subsequent high-power energy recovery and improving the total energy recovery rate.

[0076] Step P300: Integration with real-time mode.

[0077] The output of the predictive control module dynamically influences the decision boundaries of the drive mode. For example, even if the current Treq is slightly lower than T1, if a large torque is predicted to be needed soon, the VCU may enter the "hybrid drive mode" in advance to prepare for warm-up. Conversely, if a long downhill or flat road is predicted ahead, the VCU may be more inclined to extend the "single SiC drive mode".

[0078] By introducing predictive control, the system can manage energy flow more smoothly, avoiding sudden drops in efficiency due to abrupt changes in operating conditions. Real-world vehicle testing shows that in a typical long-distance transport cycle involving various road conditions such as hills, highways, and cities, compared to Example 1 which only uses instantaneous efficiency optimization, this example can further reduce overall vehicle energy consumption by approximately 2-5%, effectively improving the driving range.

[0079] Example 4,

[0080] This embodiment fundamentally innovates the motor selection of the core embodiment by using motors with different principles in a heterogeneous manner to explore deeper complementary advantages at the electromagnetic level.

[0081] In this embodiment, motor A is an integrated permanent magnet synchronous motor (IPMS). IPMSMs utilize permanent magnets and reluctance torque to achieve high power density and high efficiency in the low-to-medium speed and high-torque ranges. Its design continues to emphasize high torque output capability, maintaining a peak torque of 600 Nm, but through optimized magnetic circuit design, its high-efficiency range is more biased towards the low-to-medium speed range.

[0082] The controller is still driven by motor controller A (800A IGBT, 8kHz). The stability and current control characteristics of the IGBT are well matched to the driving requirements of the IPMSM.

[0083] In this embodiment, motor B is an electrically excited synchronous motor. The rotor magnetic field of the EESM is generated by an independent excitation winding current. By adjusting the excitation current, the strength of the magnetic field can be flexibly and precisely controlled over a wide speed range.

[0084] In the high-speed range, the EESM can maintain high torque by enhancing excitation or achieve a wider constant power speed range by weakening field control, and its iron loss control at high speeds is superior to that of the PMSM. In this embodiment, the EESM is designed with a peak torque of 800 Nm, ensuring torque at medium and low speeds through strong excitation capability, while also possessing excellent high-speed scalability and overload capacity.

[0085] The controller is still driven by motor controller B (660A SiC, 12kHz). The high-frequency, fast-response characteristics of the SiC controller are very suitable for achieving precise and efficient decoupling control of the EESM excitation current and torque current. The power coupling device (iA=3.0, iB=2.0), VCU, etc. are the same as in Example 1.

[0086] During the system calibration phase, detailed bench tests must be conducted on both the "IPMSM, IGBT controller" subsystem and the "EESM, SiC controller" subsystem to generate new efficiency map diagrams. The efficiency map characteristics of the EESM will differ significantly from those of the permanent magnet motor, with its efficiency advantages being more pronounced in the high-speed and weak-field regions.

[0087] In a mixed drive mode with low to medium speed and medium to high load, the system tends to let motor A (IPMSM) bear more torque because it may be more efficient at the corresponding speed.

[0088] In the hybrid drive mode of high-speed cruising (even with low load), the system tends to let motor B (EESM) undertake the main or even all drive tasks, because the overall efficiency of EESM under SiC drive may significantly exceed that of the IPMSM+IGBT combination in the high-speed range.

[0089] This allocation strategy allows the two motors to more thoroughly "maximize their strengths and minimize their weaknesses," with the IPMSM responsible for its strength in the "torque range" and the EESM responsible for its strength in the "high-speed range," thus potentially achieving a broader overall high-efficiency range than the "dual permanent magnet heterogeneous" scheme.

[0090] The VCU or motor controller B needs to calculate and control the optimal excitation current in real time based on the torque command and speed of motor B. This can serve as an additional optimization variable to find the excitation current value that minimizes the losses of motor B itself, while ensuring the output torque, thereby further improving system efficiency.

[0091] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A dual-motor heterogeneous electric drive system for electric heavy-duty trucks, characterized in that, include: Motor A and motor controller A, wherein the motor controller A adopts an IGBT power module; Motor B and motor controller B, wherein the motor controller B adopts a SiC MOSFET power module; A power coupling device, the input ends of which are respectively connected to the output shaft of motor A and the output shaft of motor B, is used to couple the power of the two motors and output it; the power coupling device includes a first reducer connected to motor A and a second reducer connected to motor B, the first reducer having a first reduction ratio, the second reducer having a second reduction ratio, and the first reduction ratio not being equal to the second reduction ratio; The vehicle controller, which is signal-connected to the motor controller A and the motor controller B, is configured to: acquire the vehicle's required torque in real time; and when the required torque is not greater than a first preset threshold, control the vehicle to be driven only by the motor B. When the required torque is greater than the first preset threshold and not greater than the second preset threshold, control motor A and motor B to drive together, and allocate the driving torque of motor A and motor B according to the pre-stored system efficiency model with the goal of minimizing the total system loss; when the required torque is greater than the second preset threshold, control motor A and motor B to output the maximum available torque at their current speed.

2. The dual-motor heterogeneous electric drive system according to claim 1, characterized in that, The first reduction ratio and the second reduction ratio are configured such that at the output end of the power coupling device, the first transmission chain consisting of the motor A and the first reducer and the second transmission chain consisting of the motor B and the second reducer have the same output speed.

3. The dual-motor heterogeneous electric drive system according to claim 1, characterized in that, The system efficiency model is established based on the efficiency MAP of the first subsystem composed of motor A and motor controller A, and the efficiency MAP of the second subsystem composed of motor B and motor controller B; the vehicle controller performs torque allocation by querying a pre-stored optimal torque allocation table with the required torque and motor speed as input.

4. The dual-motor heterogeneous electric drive system according to claim 1, characterized in that, The system efficiency model is established based on the efficiency MAP of the first subsystem composed of motor A and motor controller A, and the efficiency MAP of the second subsystem composed of motor B and motor controller B; the vehicle controller calculates the optimal torque distribution in real time by solving the optimization equation with the goal of minimizing the total system loss online.

5. The dual-motor heterogeneous electric drive system according to claim 1, characterized in that, A first controllable clutch is provided between the motor A and the first reducer, and / or a second controllable clutch is provided between the motor B and the second reducer; the vehicle controller is also configured to: in a mode where the vehicle is driven by only a single motor, control the disengagement of the clutch corresponding to the motor that is not activated.

6. The dual-motor heterogeneous electric drive system according to claim 1, characterized in that, The vehicle controller is also used to acquire information about the vehicle's future driving path; when distributing torque, it also makes forward-looking adjustments to the torque distribution strategy between motor A and motor B based on the load changes predicted by the information about the future driving path.

7. The dual-motor heterogeneous electric drive system according to claim 6, characterized in that, The future driving route information comes from at least one of the following: in-vehicle navigation system, vehicle network cloud data, or typical operating condition curves learned from historical driving data.

8. The dual-motor heterogeneous electric drive system according to claim 1, characterized in that, Motor A is a permanent magnet synchronous motor, and motor B is an excitation synchronous motor.

9. The dual-motor heterogeneous electric drive system according to any one of claims 1-8, characterized in that, The nominal operating current of motor controller A is greater than that of motor controller B, and the operating switching frequency of motor controller A is lower than that of motor controller B.

10. A control method applied to the dual-motor heterogeneous electric drive system according to any one of claims 1-9, characterized in that, Includes the following steps: Real-time acquisition of the vehicle's required torque and current speed; The required torque is determined to belong to one of three intervals: a first interval, a second interval, or a third interval; wherein, the first interval is not greater than a first preset threshold; the second interval is greater than the first preset threshold but not greater than a second preset threshold; and the third interval is greater than the second preset threshold. If it belongs to the first interval, it enters the single motor drive mode, and controls motor B to output torque alone, while motor A does not output drive torque; If it belongs to the second interval, it enters the hybrid drive mode. Based on the pre-stored system efficiency model, it calculates and allocates the target torque of motor A and motor B that minimizes the total system loss. If it belongs to the third range, it enters the peak power mode, controlling both motor A and motor B to output the maximum available torque at their current speed.

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