Series hybrid power device state instability mechanism analysis and feedback control method

Abstract

The invention provides a method for analyzing and controlling a state instability mechanism of a series hybrid power device. The method comprises the following steps: acquiring an energy conservation rule in the series hybrid power device; obtaining an energy transfer matching rule between parts of the series hybrid power device; deducing an energy deviation between the front power chain and the rear power chain, and determining an unstable change mechanism of the rotating speed of the engine and the bus voltage state of the high-voltage micro-grid; determining the states of the rotating speed of the engine and the bus voltage of the high-voltage micro-grid under different energy matching conditions; and taking corresponding return control measures. The method for analyzing and controlling the state instability mechanism of the series hybrid power device has the advantages of being high in control precision, high in real-time performance, fast in response, low in cost, capable of thoroughly solving the problems that the engine rotating speed and the bus voltage state of the series hybrid power device are unstable under the transient high-power working condition and the like, and can be widely applied to the field of automobiles.

Description

Technical Field

[0001] The present invention relates to energy matching technology, and particularly to an analysis method for the instability mechanism of a series hybrid power device and a feedback control method therefor. Background Art

[0002] With the development of equipment informatization and intelligence, more and more functional electrical equipment will be integrated into armored vehicles. However, due to technical barriers such as battery power density and stable performance output in the combat environment, it is difficult for purely electric-driven armored vehicles to maintain reliable operation under high-power conditions for a long time. The series hybrid power device can achieve high-power output through electromechanical energy coupling due to its structural composition. The series hybrid power device includes an engine-generator set, a composite energy storage unit, an auxiliary unit, a drive motor, and a high-voltage microgrid. Among them, devices such as the engine-generator set, the composite energy storage unit, the auxiliary unit, the drive motor, and the inverter are all connected to the high-voltage microgrid. The engine-generator set serves as the front power chain, and the composite energy storage unit, the auxiliary unit, and the drive motor constitute the rear power chain. The front power chain mainly meets the energy requirements of the power device. In addition, the composite energy storage unit also absorbs the electric energy generated by the generator as an energy relay station and meets the requirements such as air circulation and heat dissipation. The rear power chain mainly meets the driving requirements of power devices such as the drive motor under different working conditions. Under normal circumstances, the engine-generator set exerts its maximum performance in an appropriate speed range and maintains the voltage level of the high-voltage microgrid. However, under some transient high-power conditions, due to the differences in the dynamic response characteristics of the engine and the motor, there are problems of instability in the engine speed and the voltage state of the high-voltage microgrid bus.

[0003] The Chinese patent application with the application number "202311056315.3" and the invention name "An Adaptive Control Method for Electric Power Balance of an Electro-Mechanical Composite Transmission System" proposed by Beijing Institute of Technology in 2023 discloses an adaptive control method for electric power balance during voltage and current faults in a series electro-mechanical composite transmission system. It adaptively adjusts the power boundary of the drive motor according to voltage fault or current fault conditions to achieve electric power balance. However, due to the lack of analysis of voltage fault thresholds or the reasons for unstable voltage changes, the execution efficiency of its control strategy is low. The Chinese patent application with the application number "202410161193.2" and the invention name "A Method for Rapid Response of Electric Power in the Front Power Chain of an Electro-Mechanical Composite System" proposed by Beijing Institute of Technology in 2024 discloses an electric power coordination control strategy when there is a difference in the electric power response rate in an electro-mechanical composite transmission system. It improves the electric power response performance by coordinating the optimal loading curve of the generator. This solution lacks the analysis of the relationship between the overall energy flow and energy matching of the system, as well as the situation where the dynamic response of the electric power in the front power chain does not match that of the rear power chain. The Chinese patent with the patent number "ZL 202110664557.5" and the invention name "A Power Reserve Prediction Control Method for a Series Electro-Mechanical Composite Transmission System" proposed by Beijing Institute of Technology discloses a power coordination control strategy for a series electro-mechanical composite transmission system when the engine speed cannot meet the power demand. It pre-adjusts the speed of the engine-generator set through pre-speed control of the engine-generator to increase the power reserve of the engine-generator set. This solution lacks the associated research on the stability of the operating state and energy matching, which affects the execution efficiency and scalability of the control strategy.

[0004] Therefore, in the prior art, there is no solution to the problems of unstable engine speed and bus voltage in a series hybrid device under transient high-power conditions. Summary of the Invention

[0005] In view of this, the main object of the present invention is to provide an analysis and feedback control method for the instability mechanism of a series hybrid device, which has high control accuracy, strong real-time performance, fast response, low cost, and can completely solve the problems of unstable engine speed and bus voltage in a series hybrid device under transient high-power conditions.

[0006] To achieve the above object, the technical solution proposed by the present invention is as follows:

[0007] An analysis and feedback control method for the instability mechanism of a series hybrid device, comprising the following steps:

[0008] Step 1: Obtain the energy conservation law inside the components of the series hybrid power device, that is, determine the energy conservation law of the input and output of the engine in the engine-generator unit, the energy conservation law of the input and output of the generator, the energy conservation law of the input and output of the composite energy storage unit, the energy conservation law of the input and output of the auxiliary motor in the auxiliary unit, and the energy conservation law of the input and output of the drive motor in the power unit.

[0009] Step 2: Obtain the energy transfer and matching law between the components of the series hybrid power device, that is, obtain the energy transfer and matching law between the engine and the generator in the engine-generator unit, the energy transfer and matching law between the generator and the high-voltage microgrid, the energy transfer and matching law between the composite energy storage unit and the high-voltage microgrid, the energy transfer and matching law between the auxiliary motor and the high-voltage microgrid in the auxiliary unit, and the energy transfer and matching law between the drive motor and the high-voltage microgrid in the power unit, and construct the matching law caused by the change of the electric energy of the high-voltage microgrid.

[0010] Step 3: According to the matching law caused by the change of the electric energy of the high-voltage microgrid obtained in Step 2, deduce the energy deviation between the front power chain and the rear power chain, and determine the unstable change mechanism of the engine speed and the high-voltage microgrid bus voltage state.

[0011] Step 4: According to the unstable change mechanism of the engine speed and the high-voltage microgrid bus voltage state determined in Step 3, determine the states of the engine speed and the high-voltage microgrid bus voltage under different energy matching conditions.

[0012] Step 5: For the states of the engine speed and the high-voltage microgrid bus voltage under different energy matching conditions in Step 4, take corresponding feedback control measures.

[0013] In summary, the state instability mechanism analysis and feedback control method of a series hybrid power device described in the present invention first obtains the energy conservation law inside each component in the series hybrid power device, and then obtains the energy transfer matching law between the components, and constructs the matching law caused by the electric energy change of the high-voltage microgrid; on the basis of the matching law caused by the electric energy change of the high-voltage microgrid, the energy deviation between the front power chain and the rear power chain is derived, and the unstable change mechanism of the engine speed and the high-voltage microgrid bus voltage state is determined; then, the state of the engine speed and the high-voltage microgrid bus voltage under different energy matching conditions is determined; finally, the state of the engine speed and the high-voltage microgrid bus voltage is feedback controlled. The state instability mechanism analysis and feedback control method of a series hybrid power device described in the present invention accurately analyzes the energy conservation and energy transfer laws in the series hybrid power device, so it can accurately determine the state instability problem between the engine speed and the high-voltage microgrid bus voltage under some transient high-power conditions, and solve the state instability problem in a targeted manner. It can be seen that the state instability mechanism analysis and feedback control method of a series hybrid power device described in the present invention has high control accuracy, strong real-time performance, fast response, low cost and can completely solve the state instability problem between the engine speed and the high-voltage microgrid bus voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the overall flow of the state instability mechanism analysis and return control method of the series hybrid power device described in the present invention.

[0015] Figure 2 The figure is a schematic diagram of a circuit for converting the three-phase power output by the generator of the present invention into direct current power.

[0016] Figure 3 The present invention is a schematic diagram of a circuit for converting a DC power supply in an energy storage unit into DC-DC.

[0017] Figure 4 Schematic diagram of energy transfer between the high-voltage microgrid and the key components connected to it. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] Figure 1 The figure is a schematic diagram of the overall flow of the instability mechanism analysis and return control method of the series hybrid power device according to the present invention. Figure 1 As shown, the method for analyzing the instability mechanism of a series hybrid power device and controlling the state of the series hybrid power device according to the present invention comprises the following steps:

[0020] Step 1: Obtain the energy conservation law inside the components of the series hybrid power device, that is, determine the energy conservation law of the input and output of the engine in the engine-generator unit, the energy conservation law of the input and output of the generator, the energy conservation law of the input and output of the composite energy storage unit, the energy conservation law of the input and output of the auxiliary motor in the auxiliary unit, and the energy conservation law of the input and output of the drive motor in the power unit.

[0021] Step 2: Obtain the energy transfer and matching law between the components of the series hybrid power device, that is, obtain the energy transfer and matching law between the engine and the generator in the engine-generator unit, the energy transfer and matching law between the generator and the high-voltage microgrid, the energy transfer and matching law between the composite energy storage unit and the high-voltage microgrid, the energy transfer and matching law between the auxiliary motor and the high-voltage microgrid in the auxiliary unit, and the energy transfer and matching law between the drive motor and the high-voltage microgrid in the power unit, and construct the matching law caused by the change in the electric energy of the high-voltage microgrid.

[0022] Step 3: According to the matching law caused by the change in the electric energy of the high-voltage microgrid obtained in Step 2, deduce the energy deviation between the front power chain and the rear power chain, and determine the unstable change mechanism of the engine speed and the high-voltage microgrid bus voltage.

[0023] Step 4: According to the unstable change mechanism of the engine speed and the high-voltage microgrid bus voltage determined in Step 3, determine the states of the engine speed and the high-voltage microgrid bus voltage under different energy matching conditions.

[0024] Step 5: For the states of the engine speed and the high-voltage microgrid bus voltage under different energy matching conditions in Step 4, take corresponding feedback control measures.

[0025] In summary, the state instability mechanism analysis and feedback control method of a series hybrid power device described in the present invention first obtains the energy conservation law inside each component in the series hybrid power device, and then obtains the energy transfer matching law between the components, and constructs the matching law caused by the electric energy change of the high-voltage microgrid; on the basis of the matching law caused by the electric energy change of the high-voltage microgrid, the energy deviation between the front power chain and the rear power chain is derived, and the unstable change mechanism of the engine speed and the high-voltage microgrid bus voltage state is determined; then, the state of the engine speed and the high-voltage microgrid bus voltage under different energy matching conditions is determined; finally, the state of the engine speed and the high-voltage microgrid bus voltage is feedback controlled. The state instability mechanism analysis and feedback control method of a series hybrid power device described in the present invention accurately analyzes the energy conservation and energy transfer laws in the series hybrid power device, so it can accurately determine the state instability problem between the engine speed and the high-voltage microgrid bus voltage under some transient high-power conditions, and solve the state instability problem in a targeted manner. It can be seen that the state instability mechanism analysis and feedback control method of a series hybrid power device described in the present invention has high control accuracy, strong real-time performance, fast response, low cost and can completely solve the state instability problem between the engine speed and the high-voltage microgrid bus voltage.

[0026] In the method of the present invention, the step 1 specifically comprises the following steps:

[0027] Step 11: Obtain the internal energy conservation law of the engine in the engine-generator set, as follows:

[0028] W th =W m +W l ;

[0029] Among them, W th Indicates the real-time thermal energy of the engine; W m Indicates the real-time mechanical energy output by the engine; W l Indicates the real-time energy loss during the energy transfer process inside the engine.

[0030] In practical applications, the internal energy of the engine includes thermal energy and mechanical energy. Its main working process is: the thermal energy generated by the combustion of fuel in the engine cylinder drives the piston to circulate and work, and the movement of the piston drives the crankshaft to rotate around the center of the crankshaft. In other words, the engine working process covers combustion work and mechanical work. Combustion work converts chemical energy into thermal energy, and piston thrust work converts thermal energy into mechanical energy. For the convenience of analysis, the present invention simplifies the engine multi-cylinder collaborative combustion work effect to be equivalent to a single-cylinder combustion work effect in one cycle.

[0031] Step 12: Obtain the internal energy conservation law of the generator in the engine-generator set, as follows:

[0032]

[0033] Among them, represents the real-time electric power output by the generator, represents the real-time mechanical power absorbed by the generator, and η g represents the conversion efficiency of the real-time mechanical energy absorbed by the generator into real-time electric energy, and P abc represents the three-phase alternating current real-time power output by the generator.

[0034] In practical applications, the internal energy of the generator includes mechanical energy and electric energy. Its main working process is as follows: The generator shaft rotates under the drive of the engine torque and performs the movement of cutting magnetic induction lines. The magnetic field is cut by the induction coil. On the one hand, it generates a resistance that hinders the rotation of the generator shaft. On the other hand, it generates three-phase alternating current through the induction coil, that is, the generator outputs three-phase alternating current. The working process of the generator covers the work done by the torque that hinders the rotation of the generator shaft and the work done by cutting magnetic induction lines to generate three-phase alternating current. After that, the three-phase alternating current output by the generator is rectified by the converter to obtain direct current to supply power to the high-voltage microgrid.

[0035] Figure 2 is a schematic circuit diagram for converting the three-phase power output by the generator of the present invention into direct current. As Figure 2 shown, during the working process of the generator, the input shaft of the generator absorbs the mechanical energy transmitted by the engine and converts the mechanical energy into the electric energy of the output three-phase alternating current. The active power in the three-phase alternating current is further converted into the electric power of the direct current output by the converter. Here, in the three-phase alternating current, the real work is done by the active power, and the reactive power does not do work. Therefore, only the electric energy corresponding to the active power is transmitted during the energy transfer process of the three-phase alternating current. The relevant content of the active power and reactive power in the three-phase alternating current is prior art and will not be elaborated here.

[0036] Step 13: Obtain the internal energy conservation law of the composite energy storage unit, including: obtaining the power mapping relationship between the DC battery pack and the DC output terminal and obtaining the energy mapping relationship of the high-voltage microgrid;

[0037] The power mapping relationship between the DC battery pack and the DC output terminal is as follows:

[0038] P bd = P b ·η bd = U b ·I b ·η bd ;

[0039] Among them, P bd represents the real-time electric power output at the DC output terminal, P b represents the real-time electric power output by the DC battery pack, and U brepresents the real-time output voltage of the DC battery pack, I b represents the real-time output current of the DC battery pack; η bd represents the total energy conversion efficiency from the DC battery pack to the DC output terminal, and satisfies the following relationship:

[0040]

[0041] The energy mapping relationship of the high-voltage microgrid is as follows:

[0042] And, Among them, represents the real-time stored electrical energy of the high-voltage microgrid; represents the real-time electrical power absorbed or released by the high-voltage microgrid; ΔU dc represents the real-time change in the DC voltage in the high-voltage microgrid; R hvm represents the equivalent resistance of all electrical equipment in the high-voltage microgrid.

[0043] Figure 3 is the circuit schematic diagram for DC-DC conversion of the DC power output by the DC power supply in the energy storage unit that meets the requirements of the present invention. As Figure 3 shown, the composite energy storage unit includes a DC battery pack, a capacitor, and a DC-DC (DC-DC) conversion from the DC battery pack to the DC output terminal. The internal energy transfer form is electrical energy. The composite energy storage unit is an electrical energy transfer station on the high-voltage microgrid, which can both absorb electrical energy and release electrical energy. In the composite energy storage unit, the DC-DC conversion circuit is a boost circuit. The boost circuit is a prior art and will not be elaborated here. The DC-DC conversion transfers the real-time output power of the DC battery pack to the DC output terminal.

[0044] Step 14, obtain the internal energy conservation law of the auxiliary motor in the auxiliary unit, as follows:

[0045] And, Among them, represents the real-time electrical power of the auxiliary motor; ω Au represents the real-time rotational speed of the auxiliary motor; C1, C2, C3, and C4 respectively represent the first coefficient, the second coefficient, the third coefficient, and the fourth coefficient.

[0046] Step 15, obtain the internal energy conservation law of the drive motor in the power unit of the series hybrid power device, as follows:

[0047]

[0048] Among them, represents the electrical power of the drive motor, represents the mechanical power of the drive motor, and T m is the driving motor torque, and ω m is the driving motor speed.

[0049] In step 11 of the present invention, the real-time mechanical energy output by the engine Among them, the real-time mechanical power output by the engine The real-time torque of the engine The real-time speed of the engine G e (s) is the transfer function representing the inertial link with time delay, s is the Laplace operator; the real-time change in engine speed The damping torque T of the engine output shaft ec = C w ·ω e ; T g represents the real-time torque of the generator; C w represents the rotational damping coefficient of the engine output shaft; J e represents the equivalent rotational inertia of the engine; τ represents the upper limit time of the integration time period; t represents the time parameter;

[0050] The given torque of the engine Among them, the kinetic energy converted from thermal energy represents the equivalent height of the cylinder in the engine; represents the equivalent stroke from the crankshaft to the piston acting point in the engine; η p represents the conversion efficiency from thermal energy to kinetic energy; the thermal energy generated by the equivalent fuel injection amount combustion of the engine L d represents the equivalent fuel injection amount of the engine, q d represents the calorific value of diesel in the engine; η th represents the thermal efficiency of the engine.

[0051] In step 12 of the present invention, the real-time electric power output by the generator Among them, U nd represents the DC voltage obtained after inverting three-phase alternating current, and I nd represents the DC current obtained after inverting three-phase alternating current.

[0052] In step 12, the three-phase alternating current power P output by the generator abc = P a + P b + P c ; among them, the power of phase a in three-phase alternating current The power of phase b The power of phase c ua and i a respectively represent the induced voltage and induced current of phase a in three-phase alternating current, u b and i b respectively represent the induced voltage and induced current of phase b in three-phase alternating current, u c and i c respectively represent the induced voltage and induced current of phase c in three-phase alternating current; represents the power factor of three-phase alternating current, represents the power factor angle.

[0053] In step 12, the real-time mechanical power absorbed by the generator and the real-time rotational speed ω of the generator g = ω e ; among them, the excitation torque of the generator s.t.L d = L q ; ψ g represents the magnetic flux of the generator; p represents the number of pole pairs of the generator; L d and L q respectively represent the inductance in the d-axis direction and the inductance in the q-axis direction of the generator; i d and i q respectively represent the current in the d-axis direction and the current in the q-axis direction of the generator; s.t. is the abbreviation of subject to, representing the constraint condition.

[0054] In the method of the present invention, to obtain the current i d in the d-axis direction of the generator and the current i q in the q-axis direction of the generator, the following specific steps are included:

[0055] Step X1. Perform the following Clark transformation on the induced current i a of phase a, the induced current i b of phase b, and the induced current i c of phase c in the three-phase alternating current output by the generator:

[0056]

[0057] Among them, i α represents the converted current of the three-phase induced current i a , i b , and i c output by the generator in the α-axis coordinate direction, and i β represents the converted current of the three-phase induced current i a , i b , and i cThe conversion current in the β coordinate axis direction.

[0058] Step X2: Perform the following Park transformation on the conversion current i in the α coordinate axis direction obtained in Step X1 α and the conversion current i in the β coordinate axis direction β :

[0059]

[0060] where, i d represents the conversion current in the d coordinate axis direction obtained by performing the Park transformation on the conversion current i in the α coordinate axis direction α and the conversion current i in the β coordinate axis direction β , and i q represents the conversion current in the q coordinate axis direction obtained by performing the Park transformation on the conversion current i in the α coordinate axis direction α and the conversion current i in the β coordinate axis direction β .

[0061] In the method of the present invention, Step 2 specifically includes the following steps:

[0062] Step 21: Obtain the energy transfer matching law between the engine and the generator in the engine-generator unit as follows:

[0063]

[0064] where, represents the real-time mechanical power corresponding to the kinetic energy of the rotating shaft, and the power of the kinetic energy of the rotating shaft caused by the engine the power of the kinetic energy of the rotating shaft caused by the generator Δω e1 represents the change in rotational speed caused by the rotating shaft absorbing energy, and Δω e2 represents the change in rotational speed caused by the kinetic energy released by the rotating shaft; the change in rotational speed of the rotating shaft Δω e = Δω e1 + Δω e2 , and this summation is an algebraic sum. Here, the rotating shaft includes the connecting shaft fixedly connected together between the output shaft of the transmitter, the output shaft of the engine and the input shaft of the generator, and the input shaft of the generator.

[0065] In practical applications, since the mechanical energy transfer of the drive motor acting on the vehicle's driving wheels does not affect the energy matching result of the power unit, it is not necessary to consider the mechanical energy transfer between the drive motor and the coupling mechanism. The mechanical energy transfer between the components of the series hybrid power unit mainly occurs between the engine and the generator. The energy transfer process between the engine and the generator in the engine-generator unit is as follows: The mechanical energy output by the engine is transferred to the rotating shaft. Since the rotating shaft has mass, the mechanical energy transferred to the rotating shaft is absorbed by the rotating shaft in the form of kinetic energy; the rotating shaft transfers part of the kinetic energy to the generator, and the generator absorbs it in the form of mechanical energy. When the kinetic energy of the rotating shaft is positive, Δω e >0; when the kinetic energy of the rotating shaft is negative, Δω e <0. In addition, Δω e1 is the speed change brought about by the kinetic energy absorbed by the rotating shaft, and Δω e2 is the speed change brought about by the kinetic energy released by the rotating shaft. As an intermediate link in the energy transfer process from the engine to the generator, the rotating shaft absorbs energy while also releasing energy. When the energy absorbed by the rotating shaft is greater than the energy released, it cannot completely release the mechanical energy absorbed from the engine, so it will store a part of the energy. This part of the stored energy will increase the kinetic energy of the rotating shaft and accelerate the speed; when the energy absorbed by the rotating shaft is less than the energy released, in addition to releasing all the mechanical energy absorbed from the engine, it also needs to release part of its own original kinetic energy, so the energy of the rotating shaft decreases and the speed decreases; when the energy absorbed by the rotating shaft is basically the same as the energy released, it neither stores energy nor releases its own original energy, so the energy of the rotating shaft remains basically unchanged and the speed also remains basically unchanged.

[0066] Step 22: According to the energy transfer matching rules between the generator and the high-voltage microgrid, the energy transfer matching rules between the composite energy storage unit and the high-voltage microgrid, the energy transfer matching rules between the auxiliary motor in the auxiliary unit and the high-voltage microgrid, and the energy transfer matching rules between the drive motor in the power unit and the high-voltage microgrid, construct the matching rules caused by the change of the electric energy of the high-voltage microgrid, specifically as follows;

[0067]

[0068] Among them, the real-time electric power corresponding to the change of the electric energy of the high-voltage microgrid caused by the generator, the composite energy storage unit, the auxiliary motor, and the drive motor represents the real-time electric power corresponding to the change of the electric potential energy of the high-voltage microgrid caused by the generator, represents the real-time electric power corresponding to the change of the electric potential energy of the high-voltage microgrid caused by the composite energy storage unit, represents the real-time electric power corresponding to the change of the electric potential energy of the high-voltage microgrid caused by the drive motor, It represents the real-time electric power corresponding to the change in the electric potential energy of the high-voltage microgrid caused by the auxiliary motor; The value of

[0069]

[0070] wherein, It represents the real-time voltage change corresponding to the change in the electric potential energy of the high-voltage microgrid caused by the generator, It represents the real-time voltage change corresponding to the change in the electric potential energy of the high-voltage microgrid caused by the composite energy storage unit, It represents the real-time voltage change corresponding to the change in the electric potential energy of the high-voltage microgrid caused by the drive motor, It represents the real-time voltage change corresponding to the change in the electric potential energy of the high-voltage microgrid caused by the auxiliary motor.

[0071] In the method of the present invention, the electric energy absorbed by the high-voltage microgrid is regarded as positive, and the electric energy released by the high-voltage microgrid is regarded as negative.

[0072] In practical applications, the electric energy transfer between the components of the series hybrid power device mainly occurs on the high-voltage microgrid. Figure 4 It is a schematic diagram of the energy transfer between the high-voltage microgrid and the key components connected thereto. As Figure 4 shown, the electric energy transfer process between the high-voltage microgrid and the key components connected thereto in the method of the present invention is as follows: The generator, as an electric energy supply component, does not recover electric energy. The generator outputs electric energy and transfers it to the high-voltage microgrid. The high-voltage microgrid absorbs the electric energy in the form of electric potential energy, resulting in a change in the electric potential energy of the high-voltage microgrid; The composite energy storage unit has a small capacity and mainly serves as an auxiliary electric energy supply component. It can both transfer electric energy to the high-voltage microgrid and absorb electric energy from the high-voltage microgrid, and also affects the change in the electric potential energy of the high-voltage microgrid; The drive motor mainly draws electric energy from the high-voltage microgrid, but in some braking conditions, the electric energy generated by the drive motor during auxiliary braking will also be transferred to the high-voltage microgrid, resulting in a change in the electric potential energy of the high-voltage microgrid; The auxiliary motor needs to draw electric energy from the high-voltage microgrid to meet its normal working requirements. When the electric energy absorbed by the high-voltage microgrid is greater than the electric energy released, the high-voltage microgrid will store a part of the electric energy, and this part of the stored electric energy will cause the electric potential energy of the high-voltage microgrid to rise and the bus voltage in the high-voltage microgrid to rise; When the electric energy absorbed by the high-voltage microgrid is less than the electric energy released, in addition to releasing all the absorbed electric energy, the high-voltage microgrid also needs to release part of its original electric potential energy, which causes the electric potential energy of the high-voltage microgrid to decrease and the bus voltage in the high-voltage microgrid to decrease; When the electric energy absorbed by the high-voltage microgrid is basically the same as the electric energy released, the electric potential energy of the high-voltage microgrid and the bus voltage therein are basically unchanged.

[0073] In the method of the present invention, step 3 specifically includes the following steps:

[0074] Step 31: Matching rules caused by the change of high-voltage microgrid power obtained in step 22 The transformation is performed, and the real-time electric power output by the generator in step 12 is calculated. The following energy relationship is obtained:

[0075]

[0076] Step 32: Combine the energy relationship obtained in step 31 with the energy transfer matching rule obtained in step 21:

[0077]

[0078] The unstable change mechanism of engine speed and high-voltage microgrid bus voltage state is obtained as follows:

[0079]

[0080] Furthermore, the energy deviation ΔP0 between the front power chain and the rear power chain in the series hybrid device is obtained as follows:

[0081]

[0082] Step 33: When the energy deviation ΔP0≠0 between the current power chain and the subsequent power chain, According to the high-voltage microgrid energy mapping relationship obtained in step 13 and the real-time mechanical power corresponding to the rotating shaft kinetic energy in step 21, it is determined that there is an imbalance between the engine speed and the bus voltage in the high-voltage microgrid at this time, and the series hybrid power device becomes unstable.

[0083] In the method of the present invention, step 4 specifically comprises the following steps:

[0084] Step 41: When the output power of the generator is greater than the power consumption of the composite energy storage unit, the auxiliary motor, and the drive motor, that is, when When , the energy deviation ΔP0 between the front power chain and the rear power chain>0; then, It shows that the series hybrid power device has the first type of instability, and the kinetic energy of the rotating shaft of the engine-generator set and the potential energy of the high-voltage microgrid both increase. Correspondingly, the rotating shaft speed ω e , bus voltage U dc All increased, as follows:

[0085]

[0086] Step 42: When the output power of the generator is less than the power consumption of the composite energy storage unit, the auxiliary motor, and the drive motor, that is, when When ΔP0 < 0, the energy deviation between the front power chain and the rear power chain; furthermore, it indicates that the series hybrid power device experiences the second type of state instability, and the kinetic energy of the engine - generator set's rotating shaft and the electric potential energy of the high - voltage micro - grid both decrease. Correspondingly, the rotational speed ω e of the rotating shaft and the bus voltage U dc both decrease, specifically as follows:

[0087]

[0088] Step 43: When the output power of the generator is approximately equal to the power consumed by the composite energy storage unit, the auxiliary motor, and the drive motor, that is, when ΔP0 ≈ 0, the energy deviation between the front power chain and the rear power chain; furthermore, it indicates that the series hybrid power device is in a stable state, and the kinetic energy of the engine - generator set's rotating shaft and the electric potential energy of the high - voltage micro - grid both remain unchanged. Correspondingly, the rotational speed ω e of the rotating shaft and the bus voltage U dc both remain unchanged, specifically as follows:

[0089]

[0090] In the method of the present invention, step 5 specifically includes the following steps:

[0091] Step 51: For the first type of state instability in step 41, adjust the energy deviation ΔP0 < 0 between the front power chain and the rear power chain. Furthermore, reduce the kinetic energy of the engine - generator set's rotating shaft and the electric potential energy of the high - voltage micro - grid, specifically: reduce the instantaneous output power of the engine, increase the energy absorption of the composite energy storage unit or reduce the energy release of the composite energy storage unit, increase the energy consumption of the auxiliary motor, and increase the energy consumption of the drive motor.

[0092] Step 52: For the second type of state instability in step 42, adjust the energy deviation ΔP0 > 0 between the front power chain and the rear power chain. Furthermore, reduce the kinetic energy of the engine - generator set's rotating shaft and the electric potential energy of the high - voltage micro - grid, specifically: increase the instantaneous output power of the engine, reduce the energy absorption of the composite energy storage unit or increase the energy release of the composite energy storage unit, reduce the energy consumption of the auxiliary motor, and reduce the energy consumption of the drive motor.

[0093] In the above solution, the electronic switch devices used in the boost circuit and components or equipment such as converters and inverters are also controlled by the controller in the series hybrid power device because electronic switch devices are used. However, the control method of the controller is not the content described in the method of the present invention and will not be elaborated here.

[0094] In summary, the above are only the preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for analyzing the instability mechanism of a series hybrid power plant and for controlling the state, characterized in that: The state instability mechanism analysis and back-control method comprises the following steps: Step 1, obtaining the energy conservation law inside the series hybrid power device components, that is, determining the energy conservation law of the engine input and output and the energy conservation law of the generator input and output in the engine-generator unit, the energy conservation law of the composite energy storage unit input and output, the energy conservation law of the auxiliary motor input and output in the auxiliary unit, and the energy conservation law of the drive motor input and output in the power unit; Step 2, obtaining the energy transfer matching law between the components of the series hybrid power device, that is, obtaining the energy transfer matching law between the engine and the generator in the engine-generator unit, the energy transfer matching law between the generator and the high-voltage microgrid, the energy transfer matching law between the composite energy storage unit and the high-voltage microgrid, the energy transfer matching law between the auxiliary motor in the auxiliary unit and the high-voltage microgrid, and the energy transfer matching law between the drive motor in the power unit and the high-voltage microgrid, and constructing the matching law caused by the change of electric energy in the high-voltage microgrid; Step 3: According to the matching law caused by the change of high-voltage microgrid power obtained in step 2, the energy deviation between the front power chain and the rear power chain is derived, and the unstable change mechanism of the engine speed and the high-voltage microgrid bus voltage state is determined; Step 4: According to the unstable change mechanism of the engine speed and the high-voltage microgrid bus voltage state determined in step 3, determine the state of the engine speed and the high-voltage microgrid bus voltage under different energy matching conditions; Step 5: According to the state of the engine speed and the high-voltage microgrid bus voltage under different energy matching conditions in step 4, corresponding feedback control measures are taken.

2. A method for analyzing and controlling the instability mechanism of a series hybrid power device according to claim 1, characterized in that: The step 1 specifically includes the following steps: Step 11: Obtain the internal energy conservation law of the engine in the engine-generator set, as follows: IN th =In m +W l ; Among them, W th Indicates the real-time thermal energy of the engine; W m Indicates the real-time mechanical energy output by the engine; W l Indicates the real-time energy loss during the energy transfer process inside the engine; Step 12: Obtain the internal energy conservation law of the generator in the engine-generator set, as follows: in, Indicates the real-time electric power output by the generator, represents the real-time mechanical power absorbed by the generator, η g It represents the conversion efficiency of the real-time mechanical energy absorbed by the generator into real-time electrical energy, P abc Indicates the real-time three-phase AC power output by the generator; Step 13, obtaining the internal energy conservation law of the composite energy storage unit, including: obtaining the power mapping relationship between the DC battery group and the DC output terminal and obtaining the energy mapping relationship of the high-voltage microgrid; The power mapping relationship between the DC battery pack and the DC output terminal is as follows: P bd =P b ·or bd =U b ·I b ·or bd ; Among them, P bd Indicates the real-time output power of the DC output terminal, P b Indicates the real-time output power of the DC battery pack, U b Indicates the real-time output voltage of the DC battery pack, I b Indicates the real-time output current of the DC battery pack; η bd It represents the total energy conversion efficiency from the DC battery pack to the DC output terminal and satisfies the following relationship: The energy mapping relationship of the high-voltage microgrid is as follows: and, in, It means that the high-voltage microgrid stores electric energy in real time; Indicates the real-time electric power absorbed or released by the high-voltage microgrid; ΔU dc Represents the real-time change of DC voltage in the high-voltage microgrid; R hvm Represents the equivalent resistance of all electrical equipment in the high-voltage microgrid; Step 14: Obtain the internal energy conservation law of the auxiliary motor in the auxiliary unit, as follows: and, in, Indicates the real-time electric power of the auxiliary motor; ω Au Indicates the real-time speed of the auxiliary motor; C1, C2, C3, and C4 represent the first coefficient, the second coefficient, the third coefficient, and the fourth coefficient respectively; Step 15, obtaining the internal energy conservation law of the driving motor in the power unit of the series hybrid power device, as follows: in, Indicates the electric power of the driving motor, represents the mechanical power of the drive motor, and T m is the driving motor torque, ω m is the driving motor speed.

3. A method for analyzing and controlling the instability mechanism of a series hybrid power device according to claim 2, characterized in that: In step 11, the real-time mechanical energy output by the engine Among them, the real-time mechanical power output of the engine Engine real-time torque Real-time engine speed G e (s) is the transfer function of the inertial link with time delay, s is the Laplace operator; the real-time change of engine speed Damping torque T of engine output shaft ec =C w ·ω e ; T g Indicates the real-time torque of the generator; C w Indicates the rotational damping coefficient of the engine output shaft; J e represents the equivalent rotational inertia of the engine; τ represents the upper limit time of the integral time period; t represents the time parameter; Engine given torque Among them, the kinetic energy converted from thermal energy Indicates the equivalent height of the cylinder in the engine; Indicates the equivalent stroke from the crankshaft to the piston force point in the engine; η p Indicates the conversion efficiency from thermal energy to kinetic energy; the heat energy generated by the combustion of the equivalent amount of fuel injected by the engine L d Indicates the equivalent fuel injection amount of the engine, q d Indicates the calorific value of diesel in the engine; η th It represents the thermal efficiency of the engine.

4. A method for analyzing and controlling the instability mechanism of a series hybrid power device according to claim 2 or 3, characterized in that: In step 12, the real-time electric power output by the generator Among them, U nd It represents the DC voltage obtained after the three-phase AC is inverted, I nd It indicates the DC current obtained after the three-phase AC is inverted; In step 12, the three-phase AC power P output by the generator abc =P a +P b +P c ; Among them, the power of phase a in three-phase AC Phase b power Phase C power u a 、i a They represent the induced voltage and current of phase a in three-phase alternating current, and u b 、i b They represent the induced voltage and current of phase b in three-phase alternating current, u c 、i c They represent the c-phase induced voltage and c-phase induced current in the three-phase alternating current respectively; Indicates the power factor of three-phase alternating current, represents the power factor angle; In step 12, the real-time mechanical power absorbed by the generator And the real-time speed of the generator ω g =ω e ; Among them, the generator excitation torque sL d =L q ψ g represents the magnetic flux of the generator; p represents the number of pole pairs of the generator; L d , L q They represent the inductance of the generator in the d-axis direction and the q-axis direction respectively; i d 、i q They represent the current of the generator in the d-axis direction and the q-axis direction respectively; st is the abbreviation of subject to, which means the constraint condition.

5. A method for analyzing and controlling the instability mechanism of a series hybrid power device according to claim 4, characterized in that: Get the current i of the generator in the d-axis direction d , the current i of the generator in the q-axis direction q , specifically including the following steps: Step X1: The a-phase induced current i in the three-phase alternating current output by the generator is a , the b-phase induced current i b , the c-phase induced current i c Perform the following Clarke transformation: Among them, i α Represents the three-phase induced current i output by the generator a 、i b 、i c The conversion current in the direction of the α coordinate axis, i β Represents the three-phase induced current i output by the generator a 、i b 、i c The conversion current in the direction of the β coordinate axis; Step X2: convert the current i in the α coordinate axis direction obtained in step X1 α , the conversion current i in the direction of the β coordinate axis β Perform the following Parker transformation: Among them, i d Represents the conversion current i in the direction of the α coordinate axis α , the conversion current i in the direction of the β coordinate axis β The converted current in the d-axis direction obtained by Parker transformation, i q Represents the conversion current i in the direction of the α coordinate axis α , the conversion current i in the direction of the β coordinate axis β The converted current in the q-axis direction obtained by Park transformation.

6. A method for analyzing and controlling the instability mechanism of a series hybrid power device according to claim 1 or 5, characterized in that: The step 2 specifically includes the following steps: Step 21, obtaining the energy transfer matching rule between the engine and the generator in the engine-generator set, as follows: in, represents the real-time mechanical power corresponding to the kinetic energy of the rotating shaft, and The power of the kinetic energy of the rotating shaft caused by the engine The power of the rotating shaft kinetic energy caused by the generator Δω e1 Indicates the change in speed caused by the energy absorbed by the rotating shaft, Δω e2 Indicates the change in speed caused by the kinetic energy released by the rotating shaft; the change in speed of the rotating shaft Δω e =Δω e1 +Δω e2 ; Step 22, according to the energy transfer matching law between the generator and the high-voltage microgrid, the energy transfer matching law between the composite energy storage unit and the high-voltage microgrid, the energy transfer matching law between the auxiliary motor in the auxiliary unit and the high-voltage microgrid, and the energy transfer matching law between the drive motor in the power unit and the high-voltage microgrid, the matching law caused by the change of the electric energy of the high-voltage microgrid is constructed, as follows; Among them, the real-time electric power corresponding to the change of high-voltage microgrid electric energy caused by the generator, composite energy storage unit, auxiliary motor, and drive motor Indicates the real-time electric power corresponding to the change in electric potential energy of the high-voltage microgrid caused by the generator, Indicates the real-time electric power corresponding to the change in electric potential energy of the high-voltage microgrid caused by the composite energy storage unit, Indicates the real-time electric power corresponding to the change in the electric potential energy of the high-voltage microgrid caused by the driving motor, Indicates the real-time electric power corresponding to the change in electric potential energy of the high-voltage microgrid caused by the auxiliary motor; The values ​​of are as follows: in, Indicates the real-time voltage change corresponding to the change in the potential energy of the high-voltage microgrid caused by the generator, It represents the real-time voltage change corresponding to the change in the electric potential energy of the high-voltage microgrid caused by the composite energy storage unit. Indicates the real-time voltage change corresponding to the change in the electric potential energy of the high-voltage microgrid caused by the drive motor, It represents the real-time voltage change corresponding to the change in electric potential energy of the high-voltage microgrid caused by the auxiliary motor.

7. A method for analyzing and controlling the instability mechanism of a series hybrid power device according to claim 6, characterized in that: The step 3 specifically includes the following steps: Step 31: Matching rules caused by the change of high-voltage microgrid power obtained in step 22 The transformation is performed, and the real-time electric power output by the generator in step 12 is calculated. The following energy relationship is obtained: Step 32: Combine the energy relationship obtained in step 31 with the energy transfer matching rule obtained in step 21: The unstable change mechanism of engine speed and high-voltage microgrid bus voltage state is obtained as follows: Furthermore, the energy deviation ΔP0 between the front power chain and the rear power chain in the series hybrid device is obtained as follows: Step 33: When the energy deviation ΔP0≠0 between the current power chain and the subsequent power chain, According to the high-voltage microgrid energy mapping relationship obtained in step 13 and the real-time mechanical power corresponding to the rotating shaft kinetic energy in step 21, it is determined that there is an imbalance between the engine speed and the bus voltage in the high-voltage microgrid at this time, and the series hybrid power device becomes unstable.

8. A method for analyzing and controlling the instability mechanism of a series hybrid power device according to claim 7, characterized in that: The step 4 specifically includes the following steps: Step 41: When the output power of the generator is greater than the power consumption of the composite energy storage unit, the auxiliary motor, and the drive motor, that is, when When , the energy deviation ΔP0 between the front power chain and the rear power chain>0; then, It shows that the series hybrid power device has the first type of instability, and the kinetic energy of the rotating shaft of the engine-generator set and the potential energy of the high-voltage microgrid both increase. Correspondingly, the rotating shaft speed ω e , bus voltage U dc All increased, as follows: Step 42: When the output power of the generator is less than the power consumption of the composite energy storage unit, the auxiliary motor, and the drive motor, that is, when When , the energy deviation ΔP0 between the front power chain and the rear power chain is less than 0; furthermore, It shows that the second type of instability occurs in the series hybrid power device, and the kinetic energy of the rotating shaft of the engine-generator set and the potential energy of the high-voltage microgrid are reduced. Correspondingly, the rotating shaft speed ω e , bus voltage U dc All decreased, as follows: Step 43: When the output power of the generator is approximately equal to the power consumption of the composite energy storage unit, the auxiliary motor, and the drive motor, that is, when When , the energy deviation ΔP0 between the front power chain and the rear power chain is ≈ 0; furthermore, It shows that the series hybrid power device is stable, and the kinetic energy of the rotating shaft of the engine-generator set and the potential energy of the high-voltage microgrid remain unchanged. Correspondingly, the rotating shaft speed ω e , bus voltage U dc All remain unchanged, as follows:

9. A method for analyzing and controlling the instability mechanism of a series hybrid power device according to claim 8, characterized in that: The step 5 specifically includes the following steps: Step 51: for the first type of state instability in step 41, adjust the energy deviation ΔP0<0 between the front power chain and the rear power chain, thereby reducing the kinetic energy of the rotating shaft of the engine-generator set and the electric potential energy of the high-voltage microgrid, specifically: reduce the instantaneous output power of the engine, increase the energy absorption of the composite energy storage unit or reduce the energy release of the composite energy storage unit, increase the energy consumption of the auxiliary motor, and increase the energy consumption of the drive motor; Step 52, for the second type of state instability in step 42, adjust the energy deviation ΔP0>0 between the front power chain and the rear power chain, thereby reducing the kinetic energy of the rotating shaft of the engine-generator set and the electric potential energy of the high-voltage microgrid, specifically: increase the instantaneous output power of the engine, reduce the energy absorption of the composite energy storage unit or increase the energy release of the composite energy storage unit, reduce the energy consumption of the auxiliary motor, and reduce the energy consumption of the drive motor.

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