CN109204066B - Fuel cell power system and control method thereof, vehicle control unit and vehicle - Google Patents
Fuel cell power system and control method thereof, vehicle control unit and vehicle Download PDFInfo
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- CN109204066B CN109204066B CN201811337736.2A CN201811337736A CN109204066B CN 109204066 B CN109204066 B CN 109204066B CN 201811337736 A CN201811337736 A CN 201811337736A CN 109204066 B CN109204066 B CN 109204066B
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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
- Y02T10/72—Electric energy management in electromobility
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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
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02T90/40—Application of hydrogen technology to transportation, e.g. using fuel cells
Abstract
The application discloses fuel cell power system and control method, vehicle control unit, car thereof, fuel cell power system includes vehicle control unit, fuel cell engine, direct current/direct current DC/DC converter, machine controller, power battery, bypass switch and anti-reverse charging device, wherein: the fuel cell engine is respectively connected with the motor controller through a first branch and a second branch, the first branch comprises a DC/DC converter, and the second branch comprises a bypass switch and an anti-reverse charging device which are connected in series; the power battery and the DC/DC converter are connected in parallel on a direct current bus of the motor controller; and the vehicle control unit is used for controlling the on-off state of the bypass switch according to the running state of the vehicle. The power loss of the whole power system caused by the inherent energy conversion efficiency of the DC/DC converter is reduced by controlling the opening and closing state of the bypass switch according to the running state of the vehicle.
Description
Technical Field
The invention relates to the technical field of automobiles, in particular to a fuel cell power system, a control method thereof, a vehicle control unit and an automobile.
Background
The fuel cell vehicle is considered to be a new energy vehicle which is expected to replace an internal combustion engine vehicle to become a next generation road transport tool due to the advantages of high efficiency, zero emission and the like. Because the durability of the fuel cell is improved by limiting the dynamic response speed of output power, the conventional fuel cell power system generally adopts a hybrid power source formed by a fuel cell engine and a power cell to provide power for loads such as a vehicle accessory system, a motor controller and the like.
Because the output voltage of the fuel cell engine, the open-circuit voltage of the power cell and the input voltage of the motor controller are different greatly, a Direct Current/Direct Current (DC/DC) converter is required to decouple the voltage and control the power of the fuel cell engine, the power cell and the motor controller, so as to optimize the working state of the fuel cell engine. However, the DC/DC converter has inherent energy conversion efficiency, and this power loss is significant under high power fuel cell engine conditions, which in turn reduces the fuel cell power system economy.
Disclosure of Invention
The embodiment of the invention provides a fuel cell power system, a control method thereof, a vehicle control unit and a vehicle, which can reduce the power loss of the fuel cell power system.
In order to achieve the purpose of the invention, the technical scheme of the embodiment of the invention is realized as follows:
the embodiment of the invention provides a fuel cell power system, which comprises a vehicle control unit, a fuel cell engine, a DC/DC converter, a motor controller, a power cell, a bypass switch and an anti-reverse charging device, wherein:
the fuel cell engine is respectively connected with the motor controller through a first branch and a second branch, the first branch comprises a DC/DC converter, and the second branch comprises a bypass switch and an anti-reverse charging device which are connected in series; the power battery and the DC/DC converter are connected in parallel on a direct current bus of the motor controller;
and the vehicle control unit is used for controlling the on-off state of the bypass switch according to the running state of the vehicle.
In an embodiment of the present invention, the controlling of the open/close state of the bypass switch by the vehicle controller according to the driving state of the vehicle includes:
and when the running state of the vehicle is a driving state, the running speed is higher than a preset first speed threshold value and within a preset duration range, and the speed change rate of the vehicle is lower than a preset rate change rate threshold value, controlling the state of the bypass switch to be a closed state.
In an embodiment of the present invention, the controlling of the open/close state of the bypass switch by the vehicle controller according to the driving state of the vehicle includes:
and when the running state of the vehicle is a driving state and the running speed is lower than the preset first speed threshold value, controlling the state of the bypass switch to be an off state.
In an embodiment of the present invention, the controlling of the open/close state of the bypass switch by the vehicle controller according to the driving state of the vehicle includes:
and when the vehicle running state is a braking state, controlling the state of the bypass switch to be an off state.
In an embodiment of the present invention, the vehicle control unit is further configured to:
maintaining a set of equilibrium states, said set of equilibrium states including a plurality of equilibrium states, each said equilibrium state including a first operating point of said motor controller and a corresponding second operating point of said fuel cell engine, said first operating point of said motor controller including input current and input voltage of said motor controller; the second operating point of the fuel cell engine includes an output current and an output voltage of the fuel cell engine.
In an embodiment of the present invention, the vehicle control unit is further configured to:
adjusting a first operating point of the motor controller to move to an equilibrium state of greater input current and lower input voltage in the saved set of equilibrium states as a travel speed of the vehicle gradually increases; adjusting a second operating point of the fuel cell engine to move to an equilibrium state of greater output current and lower output voltage in the saved set of equilibrium states.
In an embodiment of the present invention, the vehicle control unit is further configured to:
when the running speed of the vehicle is gradually increased and the difference value between the input voltage of the motor controller and the output voltage of the fuel cell engine is smaller than or equal to a preset voltage threshold value, continuously adjusting the first operating point of the motor controller to move to a balance state of larger input current and lower input voltage in the saved balance state set, and closing the bypass switch when the input voltage of the motor controller is lower than the output voltage of the fuel cell engine.
Embodiments of the present invention also provide an automobile, including a fuel cell power system as described in any one of the above.
The embodiment of the invention also provides a control method of a fuel cell power system, wherein the fuel cell power system comprises a vehicle controller, a fuel cell engine, a DC/DC converter, a motor controller, a power cell, a bypass switch and an anti-reverse charging device, wherein: the fuel cell engine is respectively connected with the motor controller through a first branch and a second branch, the first branch comprises a DC/DC converter, and the second branch comprises a bypass switch and an anti-reverse charging device which are connected in series; the power battery and the DC/DC converter are connected in parallel on a direct current bus of the motor controller;
the control method comprises the following steps:
and controlling the fuel cell engine to be connected with the motor controller through the first branch or the second branch according to the running state of the vehicle.
The embodiment of the invention also provides a vehicle control unit, which comprises a processor and a memory, wherein:
the processor is configured to execute a control program of the fuel cell power system stored in the memory to implement the steps of the control method of the fuel cell power system as described above.
The technical scheme of the embodiment of the invention has the following beneficial effects:
according to the fuel cell power system and the control method thereof, the vehicle controller and the vehicle provided by the embodiment of the invention, the opening and closing state of the bypass switch is controlled according to the running state of the vehicle, so that the fuel cell engine is controlled to be connected with the motor controller through the DC/DC converter or bypass the DC/DC converter, the power loss of the whole fuel cell power system caused by the inherent energy conversion efficiency of the DC/DC converter is reduced, and the economy of the fuel cell power system is improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:
FIG. 1 is a schematic diagram of a fuel cell power system according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of another fuel cell power system according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a vehicle control unit according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.
As shown in fig. 1, a fuel cell power system according to an embodiment of the present invention includes a vehicle control unit 101, a fuel cell engine 102, a DC/DC converter 103, a motor controller 104, a power cell 105, a bypass switch 106, and an anti-reverse charging device 107, wherein:
the fuel cell engine 102 is connected with the motor controller 104 through a first branch circuit and a second branch circuit respectively, the first branch circuit comprises a DC/DC converter 103, and the second branch circuit comprises a bypass switch 106 and an anti-reverse charging device 107 which are connected in series; a power battery 105 and the DC/DC converter 103 are connected in parallel on a direct current bus of the motor controller 104;
the vehicle control unit 101 is configured to control an open/close state of the bypass switch 106 according to a vehicle driving state.
The vehicle controller 101 controls the fuel cell engine 102 to select a first branch where the DC/DC converter 103 is located according to the driving state of the vehicle, or a second branch formed by the bypass switch 106 and the anti-reverse charging device 107 to be directly connected to the DC bus, and further form a hybrid power source with the power battery 105 to provide power to loads such as the vehicle accessory system and the motor controller 104.
As shown in fig. 2, the fuel cell power system further includes a driving motor, an accessory system, a transmission and a transaxle, the accessory system is connected in parallel with the power cell and the DC/DC converter on a DC bus of the motor controller, the driving motor is connected to an output of the motor controller, the transmission is connected to the driving motor, and the transaxle is connected to the transmission.
In an embodiment of the present invention, the vehicle control unit 101 may establish communication connections with the fuel cell engine 102, the DC/DC converter 103, the motor Controller 104, the power battery 105, and the bypass switch 106 through a Controller Area Network (CAN) data bus.
In this embodiment, the DC/DC converter 103 may be a low-power unidirectional DC/DC converter 103. Specifically, the rated power of the DC/DC converter 103 may be less than or equal to the rated power of the fuel cell engine 102, and may be, for example, about 40% to 50% of the rated power of the fuel cell engine 102. The embodiment of the invention reduces the cost of the fuel cell power system by adopting the low-power DC/DC converter 103.
In this embodiment, the anti-reverse charging device 107 may be a power diode. The bypass switch 106 and power diode should satisfy high current high voltage safety.
In an embodiment of the present invention, the controlling the open/close state of the bypass switch 106 by the vehicle controller 101 according to the vehicle driving state includes:
and when the running state of the vehicle is a driving state, the running speed is higher than a preset first speed threshold value and within a preset time range, and the speed change rate of the vehicle is lower than a preset rate change rate threshold value, controlling the state of the bypass switch 106 to be a closed state.
In an embodiment of the present invention, the controlling the open/close state of the bypass switch 106 by the vehicle controller 101 according to the vehicle driving state includes:
and when the running state of the vehicle is a driving state and the running speed is lower than a preset first speed threshold value, controlling the state of the bypass switch 106 to be an off state.
It should be noted that, when the vehicle is running at a low speed (in this case, the vehicle may be running in a steady state or running in an unsteady state), the vehicle controller 101 according to the embodiment of the present invention controls the state of the bypass switch 106 to be the off state; and controlling the state of the bypass switch 106 to be a closed state when the vehicle runs at a high speed in a steady state.
The highway has the characteristics of stable working condition, high vehicle speed, large load, long driving distance, few braking working conditions, large variation range of power demand of a power system in the braking process and the like, so that when a vehicle runs on the highway, the common running state is high-speed steady-state running. The fuel cell power system of the embodiment of the invention allows the fuel cell engine 102 to bypass the DC/DC converter 103 and be directly connected with the anti-reverse charging device 107 through the bypass switch 106 when the vehicle runs at a high speed and in a steady state, thereby eliminating the power loss of the whole fuel cell power system caused by the inherent energy conversion efficiency of the DC/DC converter 103 and ensuring the economy of the fuel cell power system.
In an embodiment of the present invention, when the driving state of the vehicle is a driving state and the driving speed is lower than a preset first speed threshold, the vehicle controller 101 is further configured to:
the DC/DC converter 103 is controlled to draw the output current of the fuel cell engine 102 (i.e. the DC/DC converter 103 is controlled to operate in a current closed loop control mode, and the DC/DC converter 103 forces the output current of the fuel cell engine 102).
Under low speed steady state conditions, the motor controller 104 has less current demand on the hybrid power source. According to the output characteristics of the power battery 105, when the output current is small, the output voltage is high and smaller than the open circuit voltage. Therefore, the output current of the fuel cell engine 102 is extracted through the DC/DC converter 103, the open-circuit voltage decoupling of the fuel cell engine 102 and the power cell 105 is realized, the fuel cell engine 102 is allowed to select a working point with reasonable output voltage under the condition of constant power, and the durability of a power system is ensured.
In an embodiment of the present invention, the controlling of the vehicle control unit 101 according to a running state of the vehicle, the controlling of the opening and closing state of the bypass switch 106, further includes:
when the vehicle running state is the braking state, the state of the bypass switch 106 is controlled to be the off state.
In this embodiment, when the vehicle driving state is a braking state, the vehicle controller 101 is further configured to:
the DC/DC converter 103 is controlled to draw the output current of the fuel cell engine 102, and the power battery 105 is controlled to absorb the output current of the fuel cell engine 102 drawn by the DC/DC converter 103 and the current output to the DC bus by the motor controller 104.
Under the condition of brake feedback, the motor controller 104 inputs current to the direct current bus, the bypass switch 106 is opened, the DC/DC converter 103 starts to work, the output current of the fuel cell engine 102 is extracted through the DC/DC converter 103, and in the process that the power cell 105 absorbs brake energy, the load of the fuel cell engine 102 is gradually reduced, the output voltage clamp of the fuel cell engine 102 is realized, and the durability of a fuel cell power system is ensured. The power battery 105 absorbs the output currents of the fuel cell engine 102 and the motor controller 104 at the same time, and stores energy. Then, according to the operating point variation trend (stop or re-drive) of the motor controller 104, the operating point of the fuel cell engine 102 is coordinately controlled to smoothly move to a low-power or high-power operating point, so as to ensure the durability of the power system.
In an embodiment of the present invention, the vehicle control unit 101 is further configured to:
maintaining a set of equilibrium states, said set of equilibrium states including a plurality of equilibrium states, each said equilibrium state including a first operating point of said motor controller 104 and a corresponding second operating point of said fuel cell engine 102, said first operating point of said motor controller 104 including input current and input voltage of said motor controller 104; the second operating point of the fuel cell engine 102 includes the output current and the output voltage of the fuel cell engine 102.
It should be noted that the motor controller 104 of the embodiment of the present invention should have a wide input voltage range, and the target output characteristics of the power battery 105 should match the first operating point set of the motor controller 104. Before using the fuel cell power system of the embodiment of the present invention, it is first required to calculate the first operating point set of the motor controller 104 according to the target operating point set of the vehicle, and then select the target output characteristic (i.e. the voltage-current characteristic curve at a certain charge level) of the power cell 105 according to the first operating point set of the motor controller 104, while selecting the second operating point set of the fuel cell engine 102 at a constant power. One or more equilibrium states are defined, each equilibrium state including a first operating point of the motor controller 104 and a second operating point of the corresponding fuel cell engine 102. The durability of the fuel cell power system can be ensured by controlling the fuel cell engine 102 to operate at the second set of operating points.
In the equilibrium state, the output current of the DC/DC converter 103 is equal to the input current demand of the motor controller 104, and the output voltage of the DC/DC converter 103 is equal to the input voltage demand of the motor controller 104 and simultaneously equal to the output voltage of the power battery 105.
In an embodiment of the present invention, the vehicle control unit 101 is further configured to:
adjusting a first operating point of the motor controller 104 to move to an equilibrium state of greater input current and lower input voltage in the saved set of equilibrium states as the travel speed of the vehicle gradually increases; adjusting the second operating point of the fuel cell engine 102 moves to an equilibrium state of greater output current and lower output voltage in the saved set of equilibrium states.
As the vehicle speed increases, the input power demand of the motor controller 104 increases, and the actual operating point of the motor controller 104 moves to a more current and lower voltage equilibrium state in the first set of operating points, and correspondingly, the actual operating point of the fuel cell engine 102 also moves to a more current and lower voltage equilibrium state in the second set of operating points.
In an embodiment of the present invention, the vehicle control unit 101 is further configured to:
when the running speed of the vehicle gradually increases and the difference between the input voltage of the motor controller 104 and the output voltage of the fuel cell engine 102 is less than or equal to a preset voltage threshold, the first operating point of the motor controller 104 is continuously adjusted to move to the equilibrium state of a larger input current and a lower input voltage in the saved equilibrium state set, and when the input voltage of the motor controller 104 is lower than the output voltage of the fuel cell engine 102, the bypass switch 106 is closed.
It should be noted that, in the fuel cell power system according to the embodiment of the present invention, the bypass switch 106 is closed during the vehicle is accelerated to a high-speed steady state; during rapid vehicle acceleration and then a speed drop, the bypass switch 106 is not closed. When the output voltage of the fuel cell engine 102 approaches the input voltage of the motor controller 104, the first operating point of the motor controller 104 is first controlled to continue to move to the equilibrium state of higher input current and lower input voltage, and when the input voltage of the motor controller 104 is lower than the output voltage of the fuel cell engine 102, the bypass switch 106 is closed, so that the fuel cell engine 102 is ensured to continuously output current, the output voltage is prevented from greatly increasing, and the durability of the fuel cell power system is ensured. Meanwhile, when the voltage at the two ends of the bypass switch 106 is close, the switch is closed, so that the adhesion of the contactor caused by large current can be avoided.
Embodiments of the present invention also provide an automobile, including a fuel cell power system as described in any one of the above.
The embodiment of the invention also provides a control method of a fuel cell power system, wherein the fuel cell power system comprises a vehicle controller, a fuel cell engine, a DC/DC converter, a motor controller, a power cell, a bypass switch and an anti-reverse charging device, wherein: the fuel cell engine is respectively connected with the motor controller through a first branch and a second branch, the first branch comprises a DC/DC converter, and the second branch comprises a bypass switch and an anti-reverse charging device which are connected in series; the power battery and the DC/DC converter are connected in parallel on a direct current bus of the motor controller;
the control method comprises the following steps:
and controlling the fuel cell engine to be connected with the motor controller through the first branch or the second branch according to the running state of the vehicle.
In this embodiment, the DC/DC converter may be a low-power unidirectional DC/DC converter. Specifically, the rated power of the DC/DC converter may be less than or equal to the rated power of the fuel cell engine, and may be, for example, about 40% to 50% of the rated power of the fuel cell engine. The embodiment of the invention reduces the cost of the fuel cell power system by adopting the low-power DC/DC converter.
In this embodiment, the anti-reverse-charging device may be a power diode. The bypass switch and power diode should meet high current high voltage safety.
In an embodiment of the present invention, the control method includes:
and when the running state of the vehicle is a driving state, the running speed is higher than a preset first speed threshold value and within a preset time range, and the speed change rate of the vehicle is lower than a preset rate change rate threshold value, controlling the fuel cell engine to be connected with the motor controller through the second branch.
In an embodiment of the present invention, the control method includes:
and when the running state of the vehicle is a driving state and the running speed is lower than a preset first speed threshold value, controlling the fuel cell engine to be connected with the motor controller through the first branch circuit.
In the control method of the fuel cell power system according to the embodiment of the present invention, when the vehicle is running at a low speed (in this case, the vehicle may be running in a steady state or in an unsteady state), the fuel cell engine is controlled to be connected to the motor controller through the DC/DC converter; and when the vehicle runs at a high speed in a steady state, controlling the fuel cell engine to bypass the DC/DC converter and directly connecting the DC/DC converter with the motor controller through a direct current bus.
The highway has the characteristics of stable working condition, high vehicle speed, large load, long driving distance, few braking working conditions, large variation range of power demand of a power system in the braking process and the like, so that when a vehicle runs on the highway, the common running state is high-speed steady-state running. The embodiment of the invention allows the fuel cell engine to bypass the DC/DC converter and be directly connected with the anti-reverse charging device through the bypass switch when the vehicle runs at a high speed and in a steady state, thereby eliminating the power loss of the whole fuel cell power system caused by the inherent energy conversion efficiency of the DC/DC converter and ensuring the economy of the fuel cell power system.
In an embodiment of the present invention, when the driving state of the vehicle is a driving state and the driving speed is lower than a preset first speed threshold, the control method further includes:
and controlling the DC/DC converter to pump the output current of the fuel cell engine (namely controlling the DC/DC converter to work in a current closed loop control mode, and forcing the output current of the fuel cell engine by the DC/DC converter).
Under the low-speed steady-state working condition, the current demand of the motor controller on the hybrid power source is smaller. According to the output characteristics of the power battery, when the output current is small, the output voltage is high and is smaller than the open-circuit voltage. Therefore, the output current of the fuel cell engine is extracted through the DC/DC converter, the open-circuit voltage decoupling of the fuel cell engine and the power cell is realized, the fuel cell engine is allowed to select a working point with reasonable output voltage under the condition of constant power, and the durability of a power system is ensured.
In an embodiment of the present invention, the control method includes:
and when the running state of the vehicle is a braking state, controlling the fuel cell engine to be connected with the motor controller through the first branch circuit.
In this embodiment, when the vehicle running state is a braking state, the control method further includes:
and controlling the DC/DC converter to extract the output current of the fuel cell engine, and controlling the power battery to absorb the output current of the fuel cell engine extracted by the DC/DC converter and the current output to a direct current bus by the motor controller.
Under the condition of brake feedback, the motor controller inputs current to the direct current bus, the bypass switch is turned on, the DC/DC converter starts to work, the output current of the fuel cell engine is extracted through the DC/DC converter, the load of the fuel cell engine is gently reduced in the process that the power cell absorbs brake energy, the output voltage clamping of the fuel cell engine is realized, and the durability of the fuel cell power system is ensured. The power battery absorbs the output current of the fuel cell engine and the motor controller at the same time, and stores energy. And then, according to the change trend (stop or re-drive) of the working point of the motor controller, the working point of the fuel cell engine is coordinately controlled to smoothly move to a low-power or high-power working point, so that the durability of the power system is ensured.
In an embodiment of the present invention, the control method further includes:
saving a balance state set on the vehicle controller, wherein the balance state set comprises a plurality of balance states, each balance state comprises a first working point of the motor controller and a corresponding second working point of the fuel cell engine, and the first working point of the motor controller comprises the input current and the input voltage of the motor controller; the second operating point of the fuel cell engine includes an output current and an output voltage of the fuel cell engine.
It should be noted that the motor controller of the embodiment of the present invention should have a wide input voltage range, and the target output characteristic of the power battery should match the first operating point set of the motor controller. Before the control method of the fuel cell power system provided by the embodiment of the invention is used, firstly, a first operating point set of the motor controller is calculated according to a target operating point set of a vehicle, then, a target output characteristic (namely a volt-ampere characteristic curve under a certain electric quantity level) of the power cell is selected according to the first operating point set of the motor controller, and meanwhile, a second operating point set of the fuel cell engine is selected at constant power. One or more equilibrium states are defined, each equilibrium state including a first operating point of the motor controller and a second operating point of the corresponding fuel cell engine. The durability of the fuel cell power system can be ensured by controlling the fuel cell engine to operate in the second operating point set.
In the balanced state, the output current of the DC/DC converter is equal to the input current requirement of the motor controller, and the output voltage of the DC/DC converter is equal to the input voltage requirement of the motor controller and the output voltage of the power battery.
In an embodiment of the present invention, the control method further includes:
adjusting a first operating point of the motor controller to move to an equilibrium state of greater input current and lower input voltage in the saved set of equilibrium states as a travel speed of the vehicle gradually increases; adjusting a second operating point of the fuel cell engine to move to an equilibrium state of greater output current and lower output voltage in the saved set of equilibrium states.
As the vehicle speed gradually increases, the input power demand of the motor controller increases, and the actual operating point of the motor controller moves to a more current and lower voltage equilibrium state in the first operating point set, and correspondingly, the actual operating point of the fuel cell engine also moves to a more current and lower voltage equilibrium state in the second operating point set.
In an embodiment of the present invention, the control method further includes:
when the running speed of the vehicle is gradually increased and the difference value between the input voltage of the motor controller and the output voltage of the fuel cell engine is smaller than or equal to a preset voltage threshold value, continuously adjusting the first operating point of the motor controller to move to a balance state of larger input current and lower input voltage in the saved balance state set, and closing the bypass switch when the input voltage of the motor controller is lower than the output voltage of the fuel cell engine.
It should be noted that, in the control method of the fuel cell power system according to the embodiment of the present invention, the bypass switch is closed in the process of the vehicle steadily accelerating to the high-speed steady state; the bypass switch is not closed during rapid acceleration of the vehicle and then speed drop back. When the output voltage of the fuel cell engine is close to the input voltage of the motor controller, the first working point of the motor controller is controlled to continuously move to the balance state of larger input current and lower input voltage, and when the input voltage of the motor controller is lower than the output voltage of the fuel cell engine, the bypass switch is closed, so that the fuel cell engine is ensured to continuously output current, the output voltage is prevented from greatly increasing, and the durability of the fuel cell power system is ensured. Meanwhile, when the voltages at the two ends of the bypass switch are close, the switch is closed, and the adhesion of the contactor caused by large current can be avoided.
As shown in fig. 3, an embodiment of the present invention further provides a vehicle control unit, including a processor 301 and a memory 302, where:
the processor 301 is configured to execute a control program of the fuel cell power system stored in the memory 302 to implement the steps of the control method of the fuel cell power system according to any one of the above.
Embodiments of the present invention also provide a computer readable storage medium storing one or more programs, which are executable by one or more processors to implement the steps of the control method of the fuel cell power system as described in any one of the above.
The fuel cell power system and the control method thereof, the vehicle controller and the vehicle provided by the embodiment of the invention have the advantages that:
(1) by matching the output characteristics of the fuel cell engine and the power cell, the direct connection of the fuel cell engine with the direct current bus can be realized under the high-speed steady-state working condition, so that the power loss caused by a DC/DC converter is eliminated, the adoption of high-power DC/DC is avoided, and the cost of a fuel cell power system is reduced;
(2) under the low-speed steady-state working condition, the output current of the fuel cell engine is extracted through the DC/DC converter, so that the decoupling of the output voltage of the fuel cell engine and the output voltage of the power cell is realized, the fuel cell engine is allowed to select a working point with reasonable output voltage under the constant power condition, and the durability of a power system is ensured;
(3) under the condition of brake feedback, the output current of the fuel cell engine is extracted through the DC/DC converter, the reduction rate of the output current of the fuel cell engine is limited, the output voltage clamping of the fuel cell engine is realized, and the durability of a power system is ensured.
It will be understood by those skilled in the art that all or part of the steps of the above methods may be implemented by instructing the relevant hardware through a program, and the program may be stored in a storage medium, such as a read-only memory, a magnetic or optical disk, and the like. Alternatively, all or part of the steps of the foregoing embodiments may also be implemented by using one or more integrated circuits, and accordingly, each module/unit in the foregoing embodiments may be implemented in the form of hardware, and may also be implemented in the form of a software functional module. The present invention is not limited to any specific form of combination of hardware and software.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A fuel cell power system is characterized by comprising a vehicle controller, a fuel cell engine, a direct current/direct current DC/DC converter, a motor controller, a power cell, a bypass switch and an anti-reverse charging device, wherein:
the fuel cell engine is respectively connected with the motor controller through a first branch and a second branch, the first branch comprises a DC/DC converter, and the second branch comprises a bypass switch and an anti-reverse charging device which are connected in series; the power battery and the DC/DC converter are connected in parallel on a direct current bus of the motor controller;
the vehicle control unit is used for controlling the on-off state of the bypass switch according to the running state of the vehicle;
the vehicle control unit is further configured to: maintaining a set of equilibrium states, said set of equilibrium states including a plurality of equilibrium states, each said equilibrium state including a first operating point of said motor controller and a corresponding second operating point of said fuel cell engine, said first operating point of said motor controller including input current and input voltage of said motor controller; the second operating point of the fuel cell engine comprises an output current and an output voltage of the fuel cell engine;
the vehicle control unit is further configured to: adjusting a first operating point of the motor controller to move to an equilibrium state of greater input current and lower input voltage in the saved set of equilibrium states as a travel speed of the vehicle gradually increases; adjusting a second operating point of the fuel cell engine to move to an equilibrium state of greater output current and lower output voltage in the saved set of equilibrium states.
2. The fuel cell power system according to claim 1, wherein the controlling of the vehicle control unit to control the open/close state of the bypass switch according to the vehicle running state includes:
and when the running state of the vehicle is a driving state, the running speed is higher than a preset first speed threshold value and within a preset duration range, and the speed change rate of the vehicle is lower than a preset rate change rate threshold value, controlling the state of the bypass switch to be a closed state.
3. The fuel cell power system according to claim 1, wherein the controlling of the vehicle control unit to control the open/close state of the bypass switch according to the vehicle running state includes:
and when the running state of the vehicle is a driving state and the running speed is lower than a preset first speed threshold value, controlling the state of the bypass switch to be an off state.
4. The fuel cell power system according to claim 1, wherein the controlling of the vehicle control unit to control the open/close state of the bypass switch according to the vehicle running state includes:
and when the vehicle running state is a braking state, controlling the state of the bypass switch to be an off state.
5. The fuel cell power system of claim 1, wherein the vehicle controller is further configured to:
when the running speed of the vehicle is gradually increased and the difference value between the input voltage of the motor controller and the output voltage of the fuel cell engine is smaller than or equal to a preset voltage threshold value, continuously adjusting the first operating point of the motor controller to move to a balance state of larger input current and lower input voltage in the saved balance state set, and closing the bypass switch when the input voltage of the motor controller is lower than the output voltage of the fuel cell engine.
6. An automobile characterized by comprising the fuel cell power system according to any one of claims 1 to 5.
7. A control method of a fuel cell power system, the fuel cell power system comprising a vehicle control unit, a fuel cell engine, a DC/DC converter, a motor controller, a power cell, a bypass switch, and an anti-reverse charging device, wherein: the fuel cell engine is respectively connected with the motor controller through a first branch and a second branch, the first branch comprises a DC/DC converter, and the second branch comprises a bypass switch and an anti-reverse charging device which are connected in series; the power battery and the DC/DC converter are connected in parallel on a direct current bus of the motor controller;
the control method comprises the following steps:
maintaining a set of equilibrium states, said set of equilibrium states including a plurality of equilibrium states, each said equilibrium state including a first operating point of said motor controller and a corresponding second operating point of said fuel cell engine, said first operating point of said motor controller including input current and input voltage of said motor controller; the second operating point of the fuel cell engine comprises an output current and an output voltage of the fuel cell engine;
controlling the fuel cell engine to be connected with the motor controller through the first branch or the second branch according to the running state of the vehicle;
adjusting a first operating point of the motor controller to move to an equilibrium state of greater input current and lower input voltage in the saved set of equilibrium states as a travel speed of the vehicle gradually increases; adjusting a second operating point of the fuel cell engine to move to an equilibrium state of greater output current and lower output voltage in the saved set of equilibrium states.
8. The vehicle control unit is characterized by comprising a processor and a memory, wherein:
the processor is configured to execute a control program of the fuel cell power system stored in the memory to implement the steps of the control method of the fuel cell power system according to claim 7.
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| CN114204664B (en) * | 2021-12-10 | 2023-06-27 | 中国人民解放军海军工程大学 | Automatic switching circuit for voltage source type converter double power sources and switching control method thereof |
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