CN111907511A - Power control method for hybrid power system and hybrid power system - Google Patents
Power control method for hybrid power system and hybrid power system Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W10/00—Conjoint control of vehicle sub-units of different type or different function
- B60W10/04—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units
- B60W10/06—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units including control of combustion engines
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L50/00—Electric propulsion with power supplied within the vehicle
- B60L50/50—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells
- B60L50/60—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells using power supplied by batteries
- B60L50/61—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells using power supplied by batteries by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W10/00—Conjoint control of vehicle sub-units of different type or different function
- B60W10/04—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units
- B60W10/08—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units including control of electric propulsion units, e.g. motors or generators
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W10/00—Conjoint control of vehicle sub-units of different type or different function
- B60W10/24—Conjoint control of vehicle sub-units of different type or different function including control of energy storage means
- B60W10/26—Conjoint control of vehicle sub-units of different type or different function including control of energy storage means for electrical energy, e.g. batteries or capacitors
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W20/00—Control systems specially adapted for hybrid vehicles
- B60W20/10—Controlling the power contribution of each of the prime movers to meet required power demand
- B60W20/13—Controlling the power contribution of each of the prime movers to meet required power demand in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W20/00—Control systems specially adapted for hybrid vehicles
- B60W20/10—Controlling the power contribution of each of the prime movers to meet required power demand
- B60W20/15—Control strategies specially adapted for achieving a particular effect
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W2510/00—Input parameters relating to a particular sub-units
- B60W2510/24—Energy storage means
- B60W2510/242—Energy storage means for electrical energy
- B60W2510/244—Charge state
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/62—Hybrid vehicles
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/80—Technologies aiming to reduce greenhouse gasses emissions common to all road transportation technologies
- Y02T10/84—Data processing systems or methods, management, administration
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Abstract
The invention provides a power control method for a hybrid power system and the hybrid power system. In the control method, the target power of the generator is determined by considering both the efficiency value and the equivalent fuel consumption value of the power generation system comprising the engine and the first motor, so that the generator is controlled to generate the actual power of the generator based on the target power of the generator, and the driving power for driving the vehicle and the charging and discharging state of the battery are distributed based on the magnitude relation between the actual power of the generator and the requested driving power. Thus, the scheme does not need a special engine and a high-efficiency battery energy conversion technology, and can optimize the energy generation mode and the energy use mode in a cost-free mode, so that the relation between the energy generation and the energy use of the series hybrid power system is optimized.
Description
Technical Field
The present invention relates to the field of vehicles, and in particular, to a power control method for a hybrid power system and a hybrid power system using the same.
Background
In a conventional hybrid system, an engine, two electric machines (a generator and a motor), a battery, and a transmission are included. Specifically, the battery is electrically connected to both motors. The engine is mechanically drivingly coupled to the generator such that the engine can drive the generator to produce electrical energy to charge the battery. The electric motor is mechanically drivingly coupled to the transmission such that the electric motor can generate driving power for driving the vehicle using electric energy from the battery.
The series hybrid system has the advantages that the working state of the engine can always work in the optimal working area regardless of the requirement of the vehicle for driving power, and the working state of the engine is completely separated from the requirement of the vehicle for driving power (the rotating speed of the engine is completely separated from the rotating speed of the vehicle). However, in such a series hybrid system, there is a large energy loss in the energy conversion process in which the electric power generated from the engine-driven generator is used to drive the electric motor to generate the driving power, and particularly, the energy loss is increased in the process in which the generated electric power is charged to the battery and then discharged from the battery. Thus, there is a need for how to further optimize the relationship between energy production and energy usage of the series hybrid system described above.
In most existing solutions to the above-mentioned demand, the operating state of the engine is always in the optimum operating region (further, at the optimum operating point) regardless of the demand for the driving torque of the vehicle. In this way, the engine is always designed and tuned to operate in a very efficient but small operating region, and the energy conversion efficiency is improved only by energy conversion techniques (e.g., using SiC inverters), thereby satisfying the above-mentioned needs. Thus, the above-described prior art solutions suffer from the disadvantage that dedicated engines and high efficiency battery energy conversion technologies can significantly increase the cost of the prior series hybrid systems.
Disclosure of Invention
The present invention has been made in view of the state of the art described above. An object of the present invention is to provide a power control method for a hybrid system, which can optimize the relationship between energy generation and availability of a series hybrid system without increasing the cost. Another object of the present invention is to provide a hybrid system employing the above power control method for a hybrid system.
In order to achieve the above object, the present invention adopts the following technical solutions.
The invention provides a power control method for a hybrid system, wherein the hybrid system comprises an engine, a first motor, a battery and a second motor, the first motor and the second motor are electrically connected with the battery, the engine can drive the first motor to charge the battery, and the second motor can generate driving power by using electric energy of the battery, wherein the power control method comprises the following steps:
under the condition that the efficiency value (the ratio of electric energy generated by a generator to fuel consumed by the engine) of a power generation system comprising the engine and the first motor is not less than a preset value, determining a generator target power within a preset generator power range according to the requested driving power of the hybrid power system under the condition of minimum equivalent fuel consumption value, wherein the preset generator power range is determined according to the preset value; and
controlling the power generation system to generate generator actual power equal to the generator target power, distributing driving power for driving a vehicle among the generator actual power based on a magnitude relation between the generator actual power and the requested driving power, and controlling a charge-discharge state of the battery.
Preferably, allocating the driving power for driving the vehicle among the generator actual power and controlling the charge and discharge state of the battery based on the magnitude relation between the generator actual power and the requested driving power includes:
when the generator actual power is greater than the corresponding requested drive power, using a portion of the generator actual power equal to the requested drive power for driving a vehicle to travel, and using the remaining portion for driving the first electric machine to charge the battery;
when the actual power of the generator is equal to the requested driving power, enabling the actual power of the generator to be fully used for driving a vehicle to run; and is
When the generator actual power is smaller than the requested drive power, the generator actual power is entirely used to drive the vehicle to travel, and a portion of the requested drive power that is larger than the generator actual power is generated by the second electric machine using electric energy of the battery.
More preferably, the determining the target power of the generator within the predetermined power range of the generator with the minimum equivalent fuel consumption value as a condition includes:
and correspondingly to the request driving power, respectively calculating equivalent oil consumption values under different powers within the preset power range of the generator, and selecting the power corresponding to the minimum equivalent oil consumption value as the target power of the generator corresponding to the request driving power.
More preferably, the equivalent fuel consumption value is a sum of an actual fuel consumption value of the engine per unit time and a fuel consumption value equivalent to charging and discharging of the battery per unit time.
More preferably, the controlling the power generation system to generate the actual power of the generator equal to the target power of the generator includes:
and controlling the power generation system to generate the actual power of the generator according to a generator target power curve, wherein the generator target power curve is a curve representing the target power of the generator which continuously changes along with the requested driving power, and the generator target power curve is formed by fitting a plurality of discrete requested driving powers and a plurality of corresponding discrete generator target powers.
More preferably, the generator target power curve is a monotonically increasing curve.
More preferably, the function corresponding to the generator target power curve is f (x + k), where x is the requested driving power x and k is the offset magnitude of the driving power determined based on the state of charge of the battery.
More preferably, when the state of charge of the battery is greater than a first predetermined value, the offset amplitude k is a positive value;
when the state of charge of the battery is smaller than a second preset value, the offset amplitude k is a negative value; and is
And when the state of charge of the battery is greater than or equal to the second preset value and less than or equal to the first preset value, the offset amplitude k is zero.
More preferably, the first predetermined value is any one of values 0.8 to 0.9, and the second predetermined value is any one of values 0.1 to 0.2.
The invention also provides a hybrid power system which adopts the power control method for the hybrid power system in any one of the technical schemes.
By adopting the technical scheme, the invention provides a novel power control method for a hybrid power system and the hybrid power system adopting the power control method for the hybrid power system. In the control method, the target power of the generator is determined by considering both the efficiency value and the equivalent fuel consumption value of the power generation system comprising the engine and the first motor, so that the generator is controlled to generate the actual power of the generator based on the target power of the generator, and the driving power for driving the vehicle and the charging and discharging state of the battery are distributed based on the magnitude relation between the actual power of the generator and the requested driving power. Thus, the scheme does not need a special engine and a high-efficiency battery energy conversion technology, and can optimize the energy generation mode and the energy use mode in a cost-free mode, so that the relation between the energy generation and the energy use of the series hybrid power system is optimized.
Drawings
FIG. 1 is a schematic diagram illustrating the topology of a hybrid powertrain system according to the present invention, wherein solid lines represent mechanical drive couplings and dashed lines represent electrical connections.
FIG. 2 is a schematic diagram illustrating a generator target power curve derived from a power control method employed by the hybrid powertrain system of FIG. 1.
Fig. 3 is a diagram showing a corresponding generator target power curve obtained after determining an offset magnitude of a requested driving power based on the generator target power curve in fig. 2 and using the state of charge SOC.
Fig. 4 is a diagram showing a variation in the offset amplitude of the driving power with the state of charge.
Description of the reference numerals
1 engine 2, first motor 3, battery 4, second motor 5 speed changer
Detailed Description
Exemplary embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the detailed description is intended only to teach one skilled in the art how to practice the invention, and is not intended to be exhaustive or to limit the scope of the invention. In the present invention, the term "mechanically driving coupling" means that a driving force/torque can be transmitted between two members, and the two members may be directly connected or indirectly coupled via a transmission mechanism; "electrically connected" means that electrical energy can be transferred between two components.
The structure of the hybrid system according to the invention will be described first with reference to the drawings attached to the specification.
(Structure of hybrid System according to the invention)
As shown in fig. 1, the hybrid system according to the present invention includes one engine 1, two electric machines (a first electric machine 2 and a second electric machine 4), a battery 3, and a transmission 5.
In particular, the battery 3 is electrically connected to both electrical machines 2, 4. The engine 1 is mechanically drive-coupled to the first electric machine 2 as a generator, so that the engine 1 can drive the first electric machine 2 to generate electric energy to charge the battery 3. The second electric machine 4 as an electric motor is mechanically drivingly coupled to the transmission 5 such that the second electric machine 4 can generate drive power for driving the vehicle using electric energy of the battery 3, thereby enabling transmission of drive torque to the transmission 5. Thus, the engine 1 is not mechanically drivingly coupled to the transmission 5, but the second electric machine 4 is able to generate drive power to the transmission 5 using electrical energy after the engine 1 drives the first electric machine 2 to generate electrical energy to transmit drive torque to the transmission 5.
An example of the power control method for a hybrid system according to the invention employed by the above-described hybrid system will be described below.
(example of Power control method for hybrid System according to the present invention)
Fig. 2 is a diagram showing a generator target power curve obtained for explaining a power control method employed by the hybrid system in fig. 1, in which a parameter on the abscissa is a requested driving power from a control unit of the hybrid system, and a parameter on the ordinate is a generator target power, both of which have a unit of kW.
Taking the hybrid system shown in fig. 1 as an example, referring to fig. 2, in the power control method for a hybrid system according to the present invention, in the case where the efficiency value of the power generation system including the engine 1 and the first motor 2 is not less than the predetermined value (i.e., the efficiency value of the power generation system is high), the predetermined generator power range is determined. The efficiency value of the power generation system is the ratio of the electric energy generated by the first electric machine 2 as a generator to the fuel consumed by the engine 1, and mainly depends on the oil consumption of the engine 1 under different powers. The efficiency values of different power generation systems are different according to the types, functions and the like of the engine and the generator, and more electric energy can be generated with the same oil consumption under the condition that the efficiency values of the power generation systems are higher. The predetermined generator power range is a range defined by "maximum" and "minimum" on the ordinate in the figure, and the area corresponding to the lattice is an optimum range within the range. Thus, the generator target power should be determined within the above-mentioned predetermined generator power range.
Further, the control unit of the hybrid system issues a request drive power according to the running behavior of the vehicle. And determining the optimal generator target power within the preset generator power range on the basis of the request driving power and on the condition of minimum equivalent fuel consumption.
The equivalent fuel consumption value is obtained, for example, based on the fuel consumption minimization algorithm ECMS as an optimized energy management strategy. The basic idea of the ECMS algorithm is that for a charge sustaining hybrid system, the battery is an energy buffer, the energy consumed during the running of the vehicle is finally from the fuel, and the consumed battery power needs to be supplemented by the corresponding amount of fuel consumed during the following running of the vehicle, so that an equivalent relationship between the consumed battery power and the fuel needed for compensating the power needs to be established. Therefore, the equivalent fuel quantity of the fuel quantity consumed by the engine and the electric energy consumed by the battery at a certain moment is represented as a unified energy consumption index and used as a control target of the optimized control. The ECMS algorithm comprehensively considers the fuel consumption rate and the battery charging and discharging power of each instantaneous system and performs equivalence on the charging and discharging power of the battery, so that the equivalent fuel consumption value of the system is obtained, and the control with the minimum instantaneous equivalent fuel consumption value is the instantaneous control quantity. Thus, when the battery is discharged, the total equivalent fuel consumption of the system is greater than the actual fuel consumption of the engine due to the output power of the battery; conversely, when the battery is charged, the total equivalent fuel consumption of the system is less than the actual fuel consumption of the engine. In summary, in the present example, the equivalent fuel consumption value is the sum of the actual fuel consumption value per unit time of the engine 1 and the fuel consumption value equivalent to the charge and discharge of the battery 3 per unit time.
Further, for each requested driving power, the equivalent fuel consumption values of different powers within the predetermined power range of the generator corresponding to each requested driving power are respectively calculated, and the power corresponding to the minimum equivalent fuel consumption value is selected as the optimal target power of the generator within the predetermined power range of the generator corresponding to the requested driving power. Therefore, under the condition that enough discrete values of the requested driving power are selected, the discrete requested driving powers are used for respectively calculating to obtain corresponding target power of the generator, and discrete data of all the calculated target power of the generator are fitted to obtain a target power curve of the generator continuously changing along with the requested driving power. In the fitting process described above, an interpolation algorithm may be utilized to obtain a generator target power curve from these discrete data.
Further, the power generation system is controlled to generate the generator actual power equal to the generator target power according to the generator target power curve, and the driving power for driving the vehicle and the charge-discharge state of the battery 3 are distributed based on the magnitude relation between the generator actual power and the requested driving power. In fact, since the generator actual power is equal to the generator target power, the driving power can be distributed and the charge and discharge state of the battery 3 can be controlled according to the comparison between the generator target power curve and the requested driving power following curve in fig. 2.
Specifically, as shown in fig. 2, the requested driving power following curve is a straight line having a slope of 45 degrees, which is obtained such that the generator target power and the requested driving power are always equal. It should be noted that, according to the requested driving power following curve, the actual power of the generator theoretically generated to be equal to the target power of the generator is always equal to the requested driving power, so that if the curve is followed according to the requested driving power, there is no energy loss in the energy conversion process due to the charging and discharging of the battery 3.
Thus, when based on the same requested drive power, comparing the values obtained by the generator target power curve according to the present invention with the above-described requested drive power following curve makes it possible to clarify the distribution of the drive power for driving the vehicle and the charge-discharge state of the battery 3 as follows.
(a) When the generator actual power is larger than the requested drive power, a portion of the generator actual power equal to the requested drive power is used as drive power for driving the vehicle, and the remaining portion is used for driving the first electric machine 2 to charge the battery 3 (as indicated by the shaded portion at the lower left in fig. 2).
(b) When the generator actual power is equal to the requested driving power, the generator actual power is all used as the driving power for driving the vehicle (at the intersection between the generator target power curve and the requested driving power in fig. 2).
(c) When the generator actual power is smaller than the requested drive power, the generator actual power is entirely used as the drive power for driving the vehicle, and a portion of the requested drive power, which is larger than the generator actual power, is generated by the second electric machine 4 using the electric energy in the battery 3, at which time the battery 3 is discharged (as indicated by the hatched portion on the right in fig. 2).
In addition, as shown in fig. 2, the generator target power according to the present invention is a monotone increasing curve, and the slope in the vicinity of the intersection between the generator target power curve and the requested driving power is small, so that the generator target power is concentrated in the optimal range corresponding to the lattice as much as possible.
A method of adjusting the above-described generator target power curve by introducing the state of charge SOC of the battery 3 will be described below.
Fig. 3 is a diagram showing a corresponding generator target power curve obtained after determining the offset magnitude of the requested driving power using the state of charge based on the generator target power curve in fig. 2, where the parameter on the abscissa is the requested driving power from the control unit of the hybrid system, and the parameter on the ordinate is the generator target power, both of which have a unit of kW.
Referring to fig. 3, when the requested driving power is set to x and the offset amplitude k of the driving power is determined based on the state of charge of the battery 3, the function corresponding to the generator target power curve is made adjustable to f (x + k).
Different offset amplitudes k are obtained according to different states of charge, so that the function f (x) corresponding to the target power curve of the generator can be adjusted as follows.
(a) When the state of charge of the battery 3 is greater than the first predetermined value, the offset amplitude k is positive, and the function f (x + k) corresponds to the curve indicated by the two-dot chain line in fig. 3.
(b) When the state of charge of the battery 3 is smaller than the second predetermined value, the offset amplitude k is negative, and the function f (x + k) corresponds to the curve indicated by the dashed line in fig. 3.
(c) When the state of charge of the battery 3 is equal to or greater than the second predetermined value and equal to or less than the first predetermined value, the offset amplitude k is zero, and the function f (x + k) (actually, the function f (x)) corresponds to the curve indicated by the solid line in fig. 3.
In the present example, as shown in fig. 4, the first predetermined value is 0.8 and the second predetermined value is 0.2. In addition, in the variation process of the k value shown in fig. 4, when the state of charge is between 0.2 and 0.1, the k value is a negative value and the absolute value of the k value gradually increases, and when the state of charge is between 0.1 and 0, the k value is a negative value and the absolute value of the k value is the largest; correspondingly, when the state of charge is between 0.8 and 0.9, the k value is a positive value and the absolute value of the k value gradually increases, and when the state of charge is between 0.9 and 1, the k value is a positive value and the absolute value of the k value is maximum.
It should be understood that the above embodiments are only exemplary and are not intended to limit the present invention. Various modifications and alterations of the above-described embodiments may be made by those skilled in the art in light of the teachings of the present invention without departing from the scope thereof. In addition, supplementary explanation is made as follows.
i. According to the power control method for the hybrid power system, the efficiency of the power generation system and the energy conversion efficiency can be considered under the condition of not increasing the cost, so that better system efficiency is realized. With the solution according to the invention, there is no substantial impact on the physical architecture of existing series hybrid systems. The hybrid system according to the present invention can employ the geared engine 1 without requiring special design and calibration of the engine 1.
Since at least a part of the generator actual power is directly used as the requested drive power, the portion for charging the battery 3 is reduced as compared with the case where the generator actual power is used entirely for charging the battery 3, thereby reducing the energy loss caused during the charge and discharge of the battery 3 and reducing the requirements for the capacity and maximum power of the battery 3.
In addition, the target power curve of the generator can be adaptively adjusted when the state of charge is in an extreme condition, so that the extreme condition of the state of charge can be better dealt with.
Although it is described in the above embodiment that the first predetermined value is 0.8 and the second predetermined value is 0.2, the present invention is not limited thereto, and the first predetermined value may be any one of values of 0.8 to 0.9 and the second predetermined value may be any one of values of 0.1 to 0.2.
Although not specifically described in the above embodiment, it should be understood that the efficiency value of the power generation system including the engine 1 and the first electric machine 2 should be determined by combining the operating efficiency of the generator 1 and the operating efficiency of the generator.
Although not illustrated in the above specific embodiment, it should be understood that the power control method for a hybrid system according to the present invention may be executed in a control unit of a hybrid system or a vehicle control unit of a vehicle including the hybrid system, or a separate control unit may be provided to execute the power control method for a hybrid system according to the present invention. Whatever the control unit adopted, the control unit should be able to control the operating states of the engine 1, the first motor 2, the battery 3, and the second motor 4.
Claims (10)
1. A power control method for a hybrid system, the hybrid system including an engine (1), a first electric machine (2), a battery (3), and a second electric machine (4), the first electric machine (2) and the second electric machine (4) being electrically connected to the battery (3), the engine (1) being capable of driving the first electric machine (2) to charge the battery (3), the second electric machine (4) being capable of generating drive power using electric energy of the battery (3), wherein the power control method comprises:
under the condition that the efficiency value of a power generation system comprising the engine (1) and the first motor (2) is not less than a preset value, determining a target power of a generator within a preset generator power range according to the requested driving power of the hybrid power system under the condition of minimum equivalent fuel consumption value, wherein the preset generator power range is determined according to the preset value; and
controlling the power generation system to generate generator actual power equal to the generator target power, distributing drive power for driving a vehicle among the generator actual power based on a magnitude relation between the generator actual power and the requested drive power, and controlling a charge-discharge state of the battery (3).
2. The control method according to claim 1, wherein allocating drive power for driving a vehicle among the generator actual power and controlling the charge-discharge state of the battery (3) based on a magnitude relation between the generator actual power and the requested drive power includes:
when the generator actual power is greater than the corresponding requested drive power, using a portion of the generator actual power equal to the requested drive power for driving the vehicle to travel, and using the remaining portion for driving the first electric machine (2) to charge the battery (3);
when the actual power of the generator is equal to the requested driving power, enabling the actual power of the generator to be fully used for driving a vehicle to run; and is
When the generator actual power is smaller than the requested drive power, the generator actual power is entirely used for driving the vehicle to run, and a portion of the requested drive power larger than the generator actual power is generated by the second electric machine (4) using electric energy of the battery (3).
3. The control method according to claim 1 or 2, wherein determining the generator target power within a predetermined generator power range on the condition that the equivalent fuel consumption value is minimum comprises:
and correspondingly to the request driving power, respectively calculating equivalent oil consumption values under different powers within the preset power range of the generator, and selecting the power corresponding to the minimum equivalent oil consumption value as the target power of the generator corresponding to the request driving power.
4. The control method according to claim 3, characterized in that the equivalent fuel consumption value is the sum of the actual fuel consumption value of the engine (1) per unit time and the fuel consumption value equivalent to the charging and discharging of the battery (3) per unit time.
5. The control method according to claim 3, wherein controlling the power generation system to generate an actual power of the generator equal to the target power of the generator includes:
and controlling the power generation system to generate the actual power of the generator according to a generator target power curve, wherein the generator target power curve is a curve representing the target power of the generator which continuously changes along with the requested driving power, and the generator target power curve is formed by fitting a plurality of discrete requested driving powers and a plurality of corresponding discrete generator target powers.
6. The control method of claim 5, wherein the generator target power curve is a monotonically increasing curve.
7. The control method according to claim 5, characterized in that the generator target power curve corresponds to a function of f (x + k), where x is the requested drive power x and k is an offset magnitude of the drive power determined based on the state of charge of the battery (3).
8. The control method according to claim 7,
when the state of charge of the battery (3) is larger than a first preset value, the offset amplitude k is a positive value;
when the state of charge of the battery (3) is smaller than a second preset value, the offset amplitude k is a negative value; and is
And when the state of charge of the battery (3) is greater than or equal to the second preset value and less than or equal to the first preset value, the offset amplitude k is zero.
9. The control method according to claim 8, wherein the first predetermined value is any one of values 0.8 to 0.9, and the second predetermined value is any one of values 0.1 to 0.2.
10. A hybrid system characterized by employing the power control method for a hybrid system according to any one of claims 1 to 9.
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