Intelligent electromechanical transmission system and optimal control method

Abstract

The invention belongs to the field of electromechanical transmission systems and control, and provides an intelligent electromechanical transmission system and an optimal control method thereof. The intelligent electromechanical transmission system has a first output form, a second output form and a third output form. The method comprises a starting process control method and an operation process control method. According to the operation process control method, engine load rate, direct current bus voltage and motor power constraint are comprehensively considered, and engine target rotating speed is generated; respectively controlling the generator and the motor by using vector control precaution based on rotor field orientation; designing a current inner loop decoupling controller of the asynchronous motor vector control system by applying a basic method of feedback linearization; and tracking the change of the load torque by using an error-based active-disturbance-rejection constant-speed control strategy to realize constant-speed control. The optimal control method is provided mainly for the electromechanical transmission requirement, the working efficiency and stability of the transmission system are improved, and stepless speed change and transmission intelligent control are achieved through electromechanical transmission.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electromechanical transmission system and control technology, and particularly relates to an intelligent electromechanical transmission system and an optimal control method thereof. BACKGROUND

[0002] At present, advanced transmission systems of high-power mobile operation equipment mainly include power shift, mechanical-hydraulic power split type continuously variable transmission (HMCVT), electromechanical power split type continuously variable transmission (EMCVT) and the like.

[0003] The power split type continuously variable transmission scheme, which is relatively typical, includes HMCVT and EMCVT. The hydraulic power flow part of HMCVT is different in form, but the transmission chain is basically consistent. The mechanical part is different according to the shift mode, and the currently widely used forms are synchronizer and power shift. The power flow split principle of EMCVT is basically consistent with that of mechanical-hydraulic split type transmission. The mechanical power flow path is: the engine power is input by the input stage cylindrical gear, transmitted to the differential gear train, and then transmitted to the clutches K1 and K2, and then transmitted to the output end cylindrical gear for speed regulation, and then output to the central transmission, and the equivalent cylindrical gear transmission is four stages. The hydraulic power flow path is: the engine power is input by three-stage cylindrical gear transmission to the hydraulic pump, the hydraulic pump drives the hydraulic motor by high-pressure oil, and the hydraulic motor transmits power to the differential gear train by two-stage cylindrical gear transmission.

[0004] For the power shift mechanical-hydraulic power split continuously variable transmission (HMCVT) transmission scheme, the mechanical power flow path is: the engine power is input by two-stage power input cylindrical gear, transmitted to the differential gear train, and then transmitted to the clutches K1, K2, K3 and K4, and then transmitted to the output end cylindrical gear for speed regulation, and then output to the central transmission, and the equivalent cylindrical gear transmission is five stages; the hydraulic power flow path is: the engine power is input by two-stage cylindrical gear to the hydraulic pump, the hydraulic pump drives the hydraulic motor by high-pressure oil, and the hydraulic motor transmits power to the differential gear train by two-stage cylindrical gear transmission. For the power shift transmission scheme, the mechanical power flow is: the engine power is input to the main transmission, transmitted by the main transmission, and then input to the auxiliary transmission, and the cylindrical gear transmission is three stages.

[0005] The above-mentioned transmission modes generally have the following problems:

[0006] (1) The mobile device using the manual shift transmission system needs to frequently stop and shift, and the operation work intensity is large, and the operation efficiency is low.

[0007] (2) The vehicle speed is directly related to the engine speed, and the engine cannot work in the economic speed range.

[0008] (3) A large number of clutches and proportional valves are needed, and the single power route is step type transmission, and many complex reduction gear trains are needed to realize super crawling. SUMMARY

[0009] According to the technical problem proposed above, an intelligent electromechanical transmission system and an optimization control method thereof are provided. The present application mainly aims at the application demand of electromechanical transmission and control, and designs an internal combustion electromechanical transmission power system and an output form thereof including an engine, a generator, a motor and a control device, so as to realize power transmission through electromechanical transmission and meet stepless speed change in the whole speed range; and designs an optimization control method based on the internal combustion electromechanical transmission system, so as to improve the working efficiency of the transmission system. The core lies in the control of the engine speed, so as to make the engine work in the optimal efficiency zone all the time, reduce unnecessary power loss, and ensure stable operation of the system through the cooperation of the control of the engine, the generator and the motor.

[0010] The technical means adopted by the present application are as follows:

[0011] An intelligent electromechanical transmission system, comprising an engine, a generator, a motor and a control device, the intelligent electromechanical transmission system comprising a first output form, a second output form and a third output form, wherein:

[0012] The first output form takes the engine as a power source, the engine is hard connected with a generator rotor, the generator enters a power generation operation state under the dragging of the engine; the control device is connected with a generator stator through a power cable, a control device generator side converter establishes a direct current bus voltage through rectification control; the control device is connected with a motor stator through a power cable, and a control device motor side converter drives the motor to run and output power by using the direct current bus voltage;

[0013] The second output form takes the engine as a power source, the engine is hard connected with a generator rotor, the generator enters a power generation operation state under the dragging of the engine; the control device is connected with a generator stator through a power cable, a control device generator side converter establishes a direct current bus voltage through rectification control; the control device is connected with a motor stator through a power cable, and a control device motor side converter drives the motor to run and output power by using the direct current bus voltage; the generator rotor is hard connected with a power shaft and outputs power through a motor rotor hollow shaft, forming shaft power output;

[0014] The third output form takes the engine as a power source, the engine is hard connected with a generator rotor, the generator enters a power generation operation state under the dragging of the engine; the control device is connected with a generator stator through a power cable, a control device generator side converter establishes a direct current bus voltage through rectification control; the control device is connected with a motor stator through a power cable, and a control device motor side converter drives the motor to run and output power by using the direct current bus voltage; the generator rotor is hard connected with a power shaft, forming shaft power output.

[0015] The control device is composed of a generator-side converter, a motor-side converter, a DC-DC module and auxiliary equipment, the generator-side converter and the motor-side converter are the same structure, the main circuit adopts two IGBT parallel forms, including a main loop, a control power supply and a control circuit board, the generator-side converter controls the engine and the generator to maintain the stability of the intermediate DC bus voltage; the motor-side converter controls the motor to run according to the operating condition required by the operation equipment; the DC-DC module adopts a two-stage BUCK circuit, including a DC-DC main loop and a chopper reactor, and is cooperatively controlled with the generator-side converter to ensure the power generation operation of the generator, provide a DC power supply for the vehicle control system and the storage battery, and realize bidirectional energy flow; the auxiliary equipment includes a water cooling plate and a water pipe to provide cooling for the control device and dissipate the heat generated in the operation process.

[0016] The application also provides an optimization control method of an intelligent electromechanical transmission system, including a starting process control method and an operation process control method, wherein:

[0017] The starting process control method includes:

[0018] The control device boosts the storage battery to the generator-side converter through the DC / DC module to drive the generator to operate as a motor, and then drive the engine to start, when the engine reaches the starting speed, the engine enters the idle speed operation state;

[0019] The control device boosts the storage battery to the generator to establish a magnetic field through the DC / DC module, the engine drives the generator to generate three-phase alternating current, and outputs a constant DC power supply through the generator-side converter to establish a DC bus voltage;

[0020] The control device converts the DC bus voltage into three-phase alternating current to drive the motor to operate through the motor-side converter, and realizes the power output of the motor;

[0021] The control device converts the DC bus voltage into the equivalent voltage of the storage battery through the DC / DC module to charge the storage battery.

[0022] The operation process control method includes:

[0023] The control device generates an engine expected speed value according to the external input motor speed demand, the engine load rate, the DC bus voltage and the motor output power constraints in the motor target speed range.

[0024] The control device selects a speed value that can cover the expected speed value as the engine target speed value within the engine's optimal fuel economy range based on the expected engine speed value, controls the engine output power and speed according to the engine characteristic curve, and performs speed tracking control through the engine controller.

[0025] The control device uses a vector control strategy based on rotor magnetic field orientation to control the generator and motor respectively, and uses an error-based self-disturbance rejection constant speed control method to track changes in load torque, thereby achieving constant speed control of the motor to meet speed requirements.

[0026] Under the condition that the external input motor speed requirements are in a free state, if the motor speed is continuously greater than the set threshold for a certain period of time, the control device determines that the vehicle has entered a slope slipping state, and obtains uphill and downhill information through the motor rotation direction, enabling zero-speed closed-loop control to prevent the vehicle from slipping.

[0027] The control device is based on a designed constant speed control method, adopts a speed closed loop, takes zero speed as the control target, and realizes hill start assist.

[0028] Furthermore, the target engine speed is calculated as follows:

[0029] n disel =f1(P load )+f2(δ load )+f3(U dc )

[0030] Among them, n disel represents the generated target engine speed, f1 represents the engine speed power curve, f2 represents the fuel efficiency function, f3 represents the engine speed compensation function, P load represents the load power, δ load Indicates the engine load rate, U dc Indicates the DC bus voltage.

[0031] Furthermore, when the generator is controlled using the vector control strategy based on rotor magnetic field orientation, in the traction state, the generator operates in the braking state, and the engine inputs energy into the system as a prime mover; in the electric braking state, the generator operates in the traction state, and part of the energy is fed back to the engine, thereby increasing the engine speed.

[0032] Furthermore, when the motor is controlled using the rotor magnetic field orientation-based vector control strategy, the electromagnetic torque of the motor is given as follows:

[0033]

[0034] Among them, T e-lim Indicates the outer envelope limit of the motor torque command. P is a unit conversion constant lim f(δ load ) is an engine load rate adjustment coefficient, and n is the motor speed.

[0035]

[0036] f(δ load ) is used to ensure engine stability when the load is heavy, and δ Δ is the adjustment electromagnetic torque retention coefficient, K p represents the proportional coefficient.

[0037] Further, the use of error-based active disturbance rejection constant speed control strategy to track the change of load torque, specifically includes:

[0038] The relationship between the motor electromagnetic torque and the speed is expressed as:

[0039]

[0040] Where v is the motor speed, K is the unit conversion constant, T e is the motor electromagnetic torque given value, f(v) is the equivalent load torque, and m is the vehicle mass.

[0041] The motor speed v is recorded as the output y, and the motor electromagnetic torque T e is recorded as the control input u, f is the total disturbance, and r is the given speed, then the system is expressed as:

[0042]

[0043] Where b is the controller gain.

[0044] A second-order linear extended state observer ESO is constructed, and the speed error e = r-y and the function containing the total disturbance are taken as state variables x1 and x2 respectively, and the following is obtained:

[0045]

[0046] The constructed second-order linear extended state observer ESO is shown in the following formula:

[0047]

[0048] Where β1 and β2 are the observation coefficients of the extended state observer, z1 is the error observation value, z2 is the total disturbance observation value, e1 represents the total error observation value, and b0 represents the initial controller gain.

[0049] The error feedback adopts proportional integral control:

[0050] u0=kp e+k i ∫edt

[0051] wherein u0 represents error feedback control, k p represents a proportional coefficient, k i represents an integral coefficient.

[0052] The total control law is obtained as follows:

[0053]

[0054] wherein u1 is feedforward compensation control, z2 / b0 is disturbance compensation, and is used to track the influence of internal and external total disturbance on the system.

[0055] Further, the slope starting assisting specifically comprises:

[0056] The control device judges the slope parking state of the vehicle in running: when the average rotating speed of the electric motor is less than a set threshold value, the throttle pedal stroke is zero, the brake pedal is stepped on, and the system enters the slope parking state; if the rotating speed of the electric motor is greater than the set threshold value for a preset time, the slope parking state is exited.

[0057] When the vehicle enters the slope parking state, if the rotating speed of the electric motor is greater than the set threshold value for a preset time under the condition that the throttle pedal and the brake pedal are in free state, the slope coasting state is entered, the impulsive acceleration value of the vehicle at this time is calculated and recorded through data processing, and the uphill and downhill information is obtained through the rotating direction of the motor.

[0058] After the vehicle enters the slope coasting state, the zero-speed speed closed loop control is enabled, the recorded impulsive acceleration is converted into corresponding traction and braking force as feedforward, and the system dynamic adjustment time is reduced; when the vehicle is stably parked on the slope, the electromagnetic torque output value of the electric motor at this time is recorded.

[0059] When the vehicle works in the constant speed mode, the rotating speed value is directly controlled according to the set value, and is seamlessly connected with the zero-speed speed closed loop of the slope; when the vehicle works in the torque mode, if the slope is judged as downhill, the slope parking electric braking force is decayed to zero according to a preset slope, and then the normal driving mode is switched to, if the slope is judged as uphill, the torque corresponding to the throttle pedal stroke is greater than the slope parking torque, and then the normal driving mode is switched to, so that the function of automatically preventing the slope coasting is realized.

[0060] Compared with the prior art, the present application has the following advantages:

[0061] The intelligent electromechanical transmission system and the optimization control method thereof provided by the application adopt electromotive power to completely decouple the engine speed and the driving speed, and for the engine, only the speed and power variables need to be adjusted, without considering the influence of the speed on the driving speed, so that the precise control of the engine is easier to realize. The motor has a wide speed regulation range, a linear traction characteristic curve, and the adjustment of the load change and the driving speed is more accurate, and the operator driving habits can be learned and the response speed can be dynamically adjusted. In the complete working cycle, the electromotive power has stronger adaptability and more stable change for the starting, turning, and load mutation, and the overall transmission efficiency can be controlled at a high level.

[0062] The intelligent electromechanical transmission system and the optimization control method thereof provided by the application adopt electromotive power to completely decouple the engine speed and the driving speed, and for the engine, only the speed and power variables need to be adjusted, without considering the influence of the speed on the driving speed, so that the precise control of the engine is easier to realize. The motor has a wide speed regulation range, a linear traction characteristic curve, and the adjustment of the load change and the driving speed is more accurate, and the operator driving habits can be learned and the response speed can be dynamically adjusted. In the complete working cycle, the electromotive power has stronger adaptability and more stable change for the starting, turning, and load mutation, and the overall transmission efficiency can be controlled at a high level.

[0063] The intelligent electromechanical transmission system and the optimization control method thereof provided by the application adopt electromotive power to completely decouple the engine speed and the driving speed, and for the engine, only the speed and power variables need to be adjusted, without considering the influence of the speed on the driving speed, so that the precise control of the engine is easier to realize. The motor has a wide speed regulation range, a linear traction characteristic curve, and the adjustment of the load change and the driving speed is more accurate, and the operator driving habits can be learned and the response speed can be dynamically adjusted. In the complete working cycle, the electromotive power has stronger adaptability and more stable change for the starting, turning, and load mutation, and the overall transmission efficiency can be controlled at a high level.

[0064] The intelligent electromechanical transmission system and the optimization control method thereof provided by the application adopt electromotive power to completely decouple the engine speed and the driving speed, and for the engine, only the speed and power variables need to be adjusted, without considering the influence of the speed on the driving speed, so that the precise control of the engine is easier to realize. The motor has a wide speed regulation range, a linear traction characteristic curve, and the adjustment of the load change and the driving speed is more accurate, and the operator driving habits can be learned and the response speed can be dynamically adjusted. In the complete working cycle, the electromotive power has stronger adaptability and more stable change for the starting, turning, and load mutation, and the overall transmission efficiency can be controlled at a high level.

[0065] The intelligent electromechanical transmission system and the optimization control method thereof provided by the application adopt electromotive power to completely decouple the engine speed and the driving speed, and for the engine, only the speed and power variables need to be adjusted, without considering the influence of the speed on the driving speed, so that the precise control of the engine is easier to realize. The motor has a wide speed regulation range, a linear traction characteristic curve, and the adjustment of the load change and the driving speed is more accurate, and the operator driving habits can be learned and the response speed can be dynamically adjusted. In the complete working cycle, the electromotive power has stronger adaptability and more stable change for the starting, turning, and load mutation, and the overall transmission efficiency can be controlled at a high level.

[0066] Based on the above reasons, the application can be widely popularized in the fields of electromechanical transmission systems and control. BRIEF DESCRIPTION OF DRAWINGS

[0067] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced. Obviously, the accompanying drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0068] Figure 1 The figure is a schematic diagram of the intelligent electromechanical transmission system in the present application.

[0069] Figure 2 The figure is a schematic diagram of the first output form of the intelligent electromechanical transmission system in the present application.

[0070] Figure 3 The figure is a schematic diagram of the second output form of the intelligent electromechanical transmission system in the present application.

[0071] Figure 4 The figure is a schematic diagram of the third output form of the intelligent electromechanical transmission system in the present application.

[0072] Figure 5 The figure is a schematic diagram of the control device of the intelligent electromechanical transmission system in the present application.

[0073] Figure 6 The figure is a schematic diagram of the main circuit of the control device of the intelligent electromechanical transmission system in the present application.

[0074] Figure 7 The figure is a flow chart of the optimization control method of the intelligent electromechanical transmission system in the present application.

[0075] Figure 8 The figure is a signal flow chart of the optimization control strategy in the present application.

[0076] Figure 9 The figure is a schematic diagram of the rotor field-oriented vector control strategy in the present application.

[0077] Figure 10 The figure is a schematic diagram of the feedback linearization current loop decoupling control scheme in the present application.

[0078] Figure 11 The figure is a schematic diagram of the error-based active disturbance rejection constant speed control method in the present application.

[0079] Figure 12 The figure is a flow chart of the anti-slip and slope starting auxiliary control in the present application. DETAILED DESCRIPTION

[0080] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0081] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all embodiments of the present application. The following description of at least one example embodiment is merely illustrative in nature and is in no way limiting on the application or its uses. Based upon a review of the embodiments in the present application, all other embodiments that would be obvious to one of ordinary skill in the art are within the scope of the present application.

[0082] It should be noted that the terms used herein are only intended to describe specific embodiments and are not intended to limit exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise, and it should be further understood that the terms "comprise" and / or "include" when used in this specification, indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0083] Unless specifically stated otherwise, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments are not meant to limit the scope of the present application. It should also be understood that the size of the various parts shown in the figures can not be to scale for ease of illustration. Techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered as part of the specification, where appropriate. In all examples shown and discussed herein, any specific values should be interpreted as merely illustrative and not as a limitation. Thus, other examples of the exemplary embodiments can have different values. It should be noted that like reference numerals and letters refer to like items in the following drawings, and thus, once an item is defined in one drawing, it need not be discussed further in subsequent drawings.

[0084] As shown in Figure 1 The present application provides an intelligent electromechanical transmission system, comprising an engine, a generator, a motor and a control device, the intelligent electromechanical transmission system comprising a first output form, a second output form and a third output form, wherein:

[0085] As shown in Figure 2 ​As shown, the first output form is a single power output form, with the engine as the power source, the engine and the generator rotor are hard-connected, and the generator enters the power generation operation state under the drag of the engine; the control device is connected to the generator stator through a power cable, and the generator-side converter of the control device establishes a DC bus voltage through rectification control; the control device is connected to the motor stator through a power cable, and the motor-side converter of the control device uses the DC bus voltage to drive the motor to output power;

[0086] like Figure 3 As shown, the second output form is a coaxial power output form, with the engine as the power source, the engine and the generator rotor are hard-connected, and the generator enters the power generation operation state under the drag of the engine; the control device is connected to the generator stator through a power cable, and the generator-side converter of the control device establishes a DC bus voltage through rectification control; the control device is connected to the motor stator through a power cable, and the motor-side converter of the control device uses the DC bus voltage to drive the motor to operate and output power; the generator rotor is hard-connected to the power shaft and is exposed to the outside through the hollow shaft of the motor rotor to form shaft power output;

[0087] like Figure 4 As shown, the third output form is a different-axis power output form with the engine as the power source. The engine is hard-connected to the generator rotor, and the generator enters the power generation operation state under the drag of the engine; the control device is connected to the generator stator through a power cable, and the generator-side converter of the control device establishes a DC bus voltage through rectification control; the control device is connected to the motor stator through a power cable, and the motor-side converter of the control device uses the DC bus voltage to drive the motor to run and output power; the generator rotor is hard-connected to the power shaft to form shaft power output.

[0088] like Figure 5 As shown, the control device consists of a generator-side converter, a motor-side converter, a DC-DC module, and auxiliary equipment. The auxiliary equipment includes cooling devices such as water-cooling plates and water pipes, which provide cooling for the control device and dissipate heat generated during operation through coolant.

[0089] like Figure 6As shown, the generator side converter and the motor side converter have the same structure, and the main circuit of each adopts a parallel connection of two IGBTs, and is composed of a main circuit (IGBT, composite bus, support capacitor, etc.), a control power supply, a control circuit board, etc. The generator side converter controls the engine and the generator to maintain the stability of the intermediate DC bus voltage. The motor side converter controls the motor to operate according to the operating condition required by the working equipment. The DC-DC module adopts a two-stage BUCK circuit, including a DC-DC main circuit, a chopper reactor, etc., and cooperates with the generator side converter to control to ensure the power generation operation of the generator, and provides a DC power supply for the vehicle control system and the storage battery, and the energy can flow in both directions.

[0090] As shown in Figure 7 The application further provides an intelligent electromechanical transmission system optimization control method realized based on the intelligent electromechanical transmission system.

[0091] The starting process control method comprises the following steps:

[0092] The control device boosts the storage battery to the generator side converter through the DC / DC module to drive the generator to operate as a motor, and then drive the engine to start, and when the engine reaches the starting speed, the engine enters the idling state.

[0093] The control device boosts the storage battery to the generator to establish a magnetic field through the DC / DC module, the engine drives the generator to generate three-phase alternating current, and outputs a constant DC power supply through the generator side converter to establish a DC bus voltage.

[0094] The control device converts the DC bus voltage into three-phase alternating current through the motor side converter to drive the motor to operate and realize the power output of the motor.

[0095] The control device converts the DC bus voltage into the equivalent voltage of the storage battery through the DC / DC module to charge the storage battery.

[0096] The working process control method comprises the following steps:

[0097] The control device generates an engine expected speed value according to the external input motor speed demand within the motor target speed range, and comprehensively considers the constraints of the engine load rate, the DC bus voltage and the motor output power.

[0098] The control device selects a speed value covering the expected speed value as the engine target speed value within the engine optimal fuel economy range according to the engine expected speed value, controls the engine output power and speed according to the engine characteristic curve, and performs speed tracking control through the engine controller.

[0099] The control device controls the generator and the motor respectively by using a vector control strategy based on rotor field orientation, and tracks the change of the load torque by using an error-based active disturbance rejection constant-speed control method, so as to realize the motor constant-speed control to meet the speed requirement.

[0100] The control device determines that the vehicle enters the hill coasting state if the motor speed continues to be greater than a set threshold for a certain time under the condition that the externally input motor speed requirements are all in a free state, and enables the zero-speed speed closed-loop control to prevent the vehicle from coasting by obtaining the uphill and downhill information through the motor rotating direction.

[0101] The control device adopts the speed closed loop based on the designed constant-speed control method to realize the hill start assist with zero speed as the control target.

[0102] As shown in the control process signal flow diagram shown in Figure 8 , the optimization of fuel efficiency and the stable and reliable operation of the system can be realized through the joint control of the engine, the generator and the motor.

[0103] As shown in Figure 9 , after the engine target speed is generated by comprehensively considering the constraints of the load motor power, the engine load rate and the DC bus voltage, the generator and the motor are controlled respectively by using the vector control strategy based on rotor field orientation.

[0104] In specific implementation, as a preferred embodiment of the present application, when the generator is controlled by using the vector control strategy based on rotor field orientation, in the traction state, the generator works in the braking state, and the engine serves as a prime mover to input energy to the system; in the electric braking state, the generator works in the traction state, and part of the energy is fed back to the engine to increase the engine speed.

[0105] In specific implementation, as a preferred embodiment of the present application, when the motor is controlled by using the vector control strategy based on rotor field orientation, the electromagnetic torque of the motor is given as follows:

[0106]

[0107] wherein, T e-lim represents the motor torque instruction envelope line limit, is a unit conversion constant, P lim is the motor power limit, which cannot be greater than the maximum power that can be output by the current engine, f(δ load ) is an engine load rate adjustment coefficient, and n is the motor speed.

[0108]

[0109] wherein, f(δ load ) is used to ensure that the engine runs stably when the load is heavy, and δΔ is the electromagnetic torque retention coefficient K p represents a proportional coefficient.

[0110] The target of the optimization control is to ensure that the engine load rate is always the highest in the dynamic process, while ensuring system stability. A proportional control strategy is adopted to control the target load rate in the range of 96%-100%, when the load rate is greater than 100%, the engine speed is rapidly increased to prevent engine shutdown, and when the load rate is less than 96%, the engine speed is rapidly reduced to ensure optimal fuel efficiency:

[0111] f2(δ load )=Kp*25.0*(0.96-δ load )

[0112] In order to make the drive system have sufficient power output, the DC bus voltage needs to be limited within a reasonable range, and the DC bus voltage can be increased by adjusting the generator speed, i.e. the engine speed, f3(U dc ) is the engine speed compensation obtained according to the bus voltage, f3 is related to the current engine speed and load power, and a simple proportional model can be used, and approximate parameters are obtained through experiments.

[0113] As shown in Figure 10 , the basic method of feedback linearization is used to design the current inner loop decoupling controller of the motor vector control system; considering the actual operating conditions, in order to ensure the stability of the DC bus voltage when the load suddenly changes, the generator stator current excitation component and torque component need to be accurately decoupled, and load power feedforward is added to improve the dynamic performance of the system. The basic method of feedback linearization is used to design the current inner loop decoupling controller of the asynchronous motor vector control system, and load power feedforward control strategy is added.

[0114] As shown in Figure 11 , in order to further optimize the accuracy of the constant speed control when the load suddenly changes, a self-disturbance rejection constant speed control method based on error is designed, which can quickly track the change of load torque, thereby maintaining the stability of the speed in constant speed control.

[0115] In specific implementation, as a preferred embodiment of the present application, the self-disturbance rejection constant speed control strategy based on error is used to track the change of load torque, which specifically includes:

[0116] The relationship between the motor electromagnetic torque and the speed is represented as:

[0117]

[0118] Where v is the motor speed, K is the unit conversion constant, T e is the motor electromagnetic torque given value, f(v) is the equivalent load torque, and m is the mass of the vehicle.

[0119] Let the motor speed v be the output y, the motor electromagnetic torque T e Let the control input u, f be the total disturbance, and r be the given speed, then the system is represented as:

[0120]

[0121] Where b is the controller gain;

[0122] A second-order linear extended state observer ESO is constructed, and the speed error e = r - y and the function containing the total disturbance are taken as state variables x1 and x2 respectively, and the following is obtained:

[0123]

[0124] The constructed second-order linear extended state observer ESO is as follows:

[0125]

[0126] Where β1 and β2 are the observation coefficients of the extended state observer, z1 is the error observation value, z2 is the total disturbance observation value, e1 represents the total error observation value, and b0 represents the initial controller gain.

[0127] The error feedback adopts proportional integral control:

[0128] u0 = k p e + k i ∫edt

[0129] Where u0 represents error feedback control, k p represents the proportional coefficient, and k i represents the integral coefficient.

[0130] The total control law is obtained as:

[0131]

[0132] Where u1 is the feedforward compensation control, which is obtained by calculating the acceleration of the locomotive at the moment of hill coasting, and can reduce the adjustment burden of the controller and make the output quickly converge to the target value. z2 / b0 is the disturbance compensation, which is used to track the influence of the internal and external total disturbance on the system. The transition process TD can be arranged in a linear mode, that is, when the given speed suddenly increases or is smaller than a certain value, the TD output tracks the speed given according to a fixed slope, and the specific value of the slope is selected according to the actual speed tracking response speed required by the system.

[0133] For example Figure 12As shown, for the vehicle in running, first, the hill parking state judgment is carried out: when the average rotation speed of the electric motor is less than a set threshold value for a certain time, the accelerator pedal stroke is zero, the brake pedal is stepped on, and the system enters the hill parking state; if the rotation speed of the electric motor is greater than the set threshold value for a certain time at this time, the hill parking state is exited.

[0134] After the vehicle enters the hill parking state, if the rotation speed of the electric motor is greater than the set threshold value for a certain time under the condition that the accelerator pedal and the brake pedal are both in the free state, the hill coasting state is entered, the impulsive acceleration value of the vehicle at this time is calculated and recorded through data processing, and the uphill and downhill information is obtained through the rotation direction of the motor.

[0135] After the vehicle enters the hill coasting state, the zero-speed speed closed-loop control is enabled, the recorded acceleration is converted into the corresponding traction and braking force as a feedforward, and the system dynamic adjustment time is reduced. When the vehicle is stably parked on the hill, the electromagnetic torque output value of the electric motor at this time is recorded.

[0136] When the vehicle starts on the hill, if the whole vehicle works in the constant speed mode, the control can be directly carried out according to the set rotation speed value, and the seamless connection with the hill zero-speed speed closed loop is realized. If the whole vehicle works in the torque mode, when the hill is judged to be downhill, the hill parking electric braking force is first decayed to zero according to a certain slope, and then the normal driving mode is switched to, if the hill is judged to be uphill, the torque corresponding to the accelerator pedal stroke is required to be greater than the hill parking torque, and then the normal driving mode is switched to, so that the function of automatically preventing the hill coasting is realized. The hill starting auxiliary control method adopted is obtained through the calculation and analysis of the impulsive acceleration of the whole vehicle in the free state, the hill information and the torque preset value are obtained without the need of the inclination sensor, and the method conforms to the actual application working condition.

[0137] In the specific implementation, an operator sets the rotation speed of the electric motor as the external input demand through a pedal or a handle, the control of the power output shaft is realized by controlling the engine rotation speed, the process of clutching and shifting in the traditional mechanical transmission system is omitted, the operation is simple, and the vehicle walking system and the power output shaft are independently controllable.

[0138] The application provides an intelligent electromechanical transmission system, which takes an engine as a power source and adopts a "AC-DC-AC" electromechanical transmission power system composed of the engine, a generator and an electric motor. A control device is used as an intelligent control core of a transmission system and controls the output power and rotation speed of the engine according to an engine characteristic curve. The generator is driven by the engine and enters a power generation state, and a generator side converter of the control device controls rectification to establish a stable DC bus voltage. An electric motor side converter of the control device drives the electric motor to operate by using the DC bus voltage, power transmission and accurate control are realized by an optimization control method, and the intelligent electromechanical transmission system meets the operation conditions of multiple scenes such as tractors and engineering machinery.

[0139] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An intelligent electromechanical transmission system, characterized in that: include: Engine, generator, motor and control device, the intelligent electromechanical transmission system includes a first output form, a second output form and a third output form, wherein: The first output form uses the engine as a power source, the engine is hard-connected to the generator rotor, and the generator enters a power generation operation state under the drag of the engine; the control device is connected to the generator stator via a power cable, and the generator-side converter of the control device establishes a DC bus voltage through rectification control; the control device is connected to the motor stator via a power cable, and the motor-side converter of the control device uses the DC bus voltage to drive the motor to operate and output power; The second output form uses the engine as the power source, the engine is hard-connected to the generator rotor, and the generator enters the power generation operation state under the drag of the engine; the control device is connected to the generator stator through a power cable, and the generator-side converter of the control device establishes a DC bus voltage through rectification control; the control device is connected to the motor stator through a power cable, and the motor-side converter of the control device uses the DC bus voltage to drive the motor to operate and output power; the generator rotor is hard-connected to the power shaft and is externally connected through the hollow shaft of the motor rotor to form shaft power output; The third output form uses the engine as a power source, the engine is hard-connected to the generator rotor, and the generator enters a power generation operation state under the drag of the engine; the control device is connected to the generator stator via a power cable, and the generator-side converter of the control device establishes a DC bus voltage through rectification control; the control device is connected to the motor stator via a power cable, and the motor-side converter of the control device uses the DC bus voltage to drive the motor to operate and output power; the generator rotor is hard-connected to the power shaft to form a shaft power output; The control device consists of a generator-side converter, a motor-side converter, a DC-DC module and auxiliary equipment; the generator-side converter and the motor-side converter have the same structure, and the main circuit adopts two IGBTs in parallel, including a main circuit, a control power supply, and a control circuit board. The generator-side converter controls the engine and generator to maintain the stability of the intermediate DC bus voltage; the motor-side converter controls the motor to make the motor operate according to the operating conditions required by the operating equipment; the DC-DC module adopts a two-stage BUCK circuit, including a DC-DC main circuit and a chopper inductor, and coordinates control with the generator-side converter to ensure the power generation operation of the generator and provide DC power for the vehicle control system and battery to achieve two-way energy flow; the auxiliary equipment includes cooling equipment such as water-cooled plates and water pipes to provide cooling for the control device and dissipate the heat generated during the operation through the coolant.

2. An optimization control method for an intelligent electromechanical transmission system implemented based on the intelligent electromechanical transmission system of claim 1, characterized in that: include: Start-up process control method and operation process control method, including: The startup process control method comprises: The control device boosts the battery voltage through the DC / DC module to supply power to the generator-side converter, driving the generator to operate as a motor, thereby starting the engine. When the engine reaches the starting speed, the engine enters the idle running state; The control device boosts the battery voltage through the DC / DC module to generate a magnetic field for the generator. The engine drives the generator to generate three-phase AC power, which is then rectified by the generator-side converter to output a constant DC power supply and establish a DC bus voltage. The control device converts the DC bus voltage into three-phase AC power through the motor-side converter to drive the motor to operate and realize the motor power output; The control device converts the DC bus voltage into the battery equivalent voltage through the DC / DC module to charge the battery; The operation process control method includes: The control device generates a desired engine speed value within the target motor speed range based on the externally input motor speed demand and the constraints of the engine load factor, DC bus voltage, and motor output power; The control device selects a speed value that covers the desired speed within the engine's optimal fuel economy range as the engine target speed based on the desired engine speed, controls the engine output power and speed according to the engine characteristic curve, and performs speed tracking control through the engine controller; The control device uses a vector control strategy based on rotor magnetic field orientation to control the generator and motor respectively, and uses an error-based self-disturbance rejection constant speed control method to track changes in load torque, achieving constant speed control of the motor to meet speed requirements; Under the condition that the external input motor speed demand is in a free state, if the motor speed is continuously greater than the set threshold for a certain period of time, the control device determines that the vehicle has entered a slope slip state, obtains uphill and downhill information through the motor rotation direction, and enables zero-speed closed-loop control to prevent the vehicle from slipping; The control device is based on a designed constant speed control method, adopts a speed closed loop, takes zero speed as the control target, and realizes hill start assist.

3. The intelligent electromechanical transmission system optimization control method according to claim 2, characterized in that: The calculation method of the target engine speed is as follows: n disel =f1(P load )+f2(δ load )+f3(U dc ) Among them, n disel represents the generated target engine speed, f1 represents the engine speed power curve, f2 represents the fuel efficiency function, f3 represents the engine speed compensation function, P load represents the load power, δ load Indicates the engine load rate, U dc Indicates the DC bus voltage.

4. The intelligent electromechanical transmission system optimization control method according to claim 2, characterized in that: When the generator is controlled using the rotor magnetic field orientation-based vector control strategy, in the traction state, the generator operates in the braking state, and the engine inputs energy into the system as a prime mover; in the electric braking state, the generator operates in the traction state, and part of the energy is fed back to the engine, increasing the engine speed.

5. The intelligent electromechanical transmission system optimization control method according to claim 2, characterized in that: When the motor is controlled using the rotor magnetic field orientation-based vector control strategy, the electromagnetic torque of the motor is given as: Among them, T e-lim Indicates the outer envelope limit of the motor torque command. is the unit conversion constant, P lim is the motor power limit, f(δ load ) is the engine load rate adjustment coefficient, n is the motor speed; Among them, f(δ load ) is used to ensure stable engine operation when the load is heavy, Δ is the electromagnetic torque retention coefficient during regulation, K p Represents the proportionality factor.

6. The intelligent electromechanical transmission system optimization control method according to claim 2, characterized in that: The method of tracking the change of load torque by using the error-based self-disturbance rejection constant speed control strategy specifically includes: The relationship between the electromagnetic torque and speed of the motor is expressed as: Where v is the motor speed, K is the unit conversion constant, T e is the given value of the electromagnetic torque of the motor, f(v) is the equivalent load torque, and m is the vehicle mass; The motor speed v is recorded as output y, and the motor electromagnetic torque T e Denote it as the control input u, f as the total disturbance, and r as the given speed, then the system can be expressed as: Where b is the controller gain; Construct a second-order linear extended state observer ESO, which takes the speed deviation e=ry and the function containing the total disturbance as As state variables x1 and x2 respectively, we get: The constructed second-order linear extended state observer ESO is shown as follows: Where β1 and β2 are the observation coefficients of the extended state observer, z1 is the error observation value, z2 is the total disturbance observation value, e1 represents the total error observation value, and b0 represents the initial controller gain; Error feedback adopts proportional integral control: u0=k p e+k i ∫edt Where u0 represents error feedback control, k p represents the proportionality coefficient, k i represents the integral coefficient; The overall control law is obtained: Among them, u1 is the feedforward compensation control, and z2 / b0 is the disturbance compensation, which is used to track the impact of internal and external total disturbances on the system.

7. The intelligent electromechanical transmission system optimization control method according to claim 2, characterized in that: The hill start assist specifically includes: The control device determines the hill parking state of a moving vehicle: when the average motor speed is less than a set threshold, the accelerator pedal travel is zero, and the brake pedal is pressed, the system enters the hill parking state; at this time, if the motor speed continues to be greater than the set threshold for a preset time, the hill parking state is exited; When the vehicle enters the slope parking state, under the condition that both the accelerator pedal and the brake pedal are in the free state, if the motor speed is continuously greater than the set threshold for a preset time, the vehicle enters the slope rolling state, and the impulse acceleration value of the vehicle at this time is calculated and recorded through data processing, and the uphill and downhill information is obtained through the motor rotation direction; After the vehicle enters the slope rolling state, zero-speed closed-loop control is enabled, and the recorded impulse acceleration is converted into the corresponding traction braking force as feedforward to reduce the dynamic adjustment time of the system; when the vehicle is stably stopped on the slope, the electromagnetic torque output value of the motor at this time is recorded. When starting on a slope, if the vehicle is working in constant speed mode, it is directly controlled according to the set speed value, and seamlessly connected with the slope zero speed closed loop; if the vehicle is working in torque mode, when the slope is judged to be downhill, the slope parking electric braking force will be decayed to zero according to the preset slope, and then switched to normal driving mode. If it is judged to be uphill, the torque given by the accelerator pedal travel is required to be greater than the slope parking torque before switching to normal driving mode, realizing the function of automatically preventing the vehicle from slipping on the slope.

Images