Fuel cell system without direct current converter

Abstract

The invention discloses a fuel cell system without a direct-current converter, and relates to the technical field of high-voltage platform architecture of hydrogen fuel cell systems, and the system comprises a fuel cell module which is used for generating electric energy; the whole vehicle power module comprises a first high-voltage power distribution unit, a bidirectional DCDC unit and an energy storage unit, the first high-voltage power distribution unit is used for obtaining the electric energy, and the bidirectional DCDC unit is used for achieving energy conversion between the first high-voltage power distribution unit and the energy storage unit.

Description

Technical Field

[0001] The present application relates to the technical field of high-voltage platform architecture of hydrogen fuel cell systems, and in particular to a fuel cell system without a direct current converter. Background Art

[0002] At present, the high-voltage architecture of hydrogen fuel cell systems all include DCDC power units. DCDC is responsible for converting the unstable DC voltage output by the battery stack into a stable DC voltage to power the vehicle's power batteries and high-voltage components.

[0003] However, in this high-voltage architecture, DCDC is the core component of the fuel cell system, and the cost of DCDC is also one of the top costs of the fuel cell system. At present, with the increasingly mature technical indicators of the fuel cell stack, such as reliability, dynamic response, and life, it is necessary to design a new high-voltage architecture to reduce the fuel cell system's dependence on DCDC and reduce the cost of the fuel cell system. At present, there is no appropriate method to solve the above problems. Therefore, it is necessary to propose a fuel cell system without a DC converter to at least solve some of the above problems. Summary of the invention

[0004] A series of simplified concepts are introduced in the Summary of the Invention section, which will be further described in detail in the Detailed Description of the Invention section. The Summary of the Invention section of this application does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0005] In a first aspect, an embodiment of the present application provides a fuel cell system without a DC converter, the system comprising:

[0006] A fuel cell module, wherein the fuel cell module is used to generate electrical energy;

[0007] A vehicle power module, the vehicle power module includes a first high-voltage distribution unit, a bidirectional DCDC unit and an energy storage unit, the first high-voltage distribution unit is used to obtain the electric energy, and the bidirectional DCDC unit is used to realize energy conversion between the first high-voltage distribution unit and the energy storage unit.

[0008] In one embodiment of the present invention, the fuel cell module comprises: a fuel cell stack and a second high-voltage power distribution unit;

[0009] The fuel cell stack is used to obtain chemical energy from fuel and convert the chemical energy into electrical energy according to electrochemical reaction;

[0010] The second high-voltage power distribution unit is used to distribute the electric energy.

[0011] In one embodiment of the present invention, the second high-voltage power distribution unit includes: a residual hydrogen discharge switch, a voltage sensor, a current sensor, a protector and an integrated air compressor controller;

[0012] The voltage sensor is connected in parallel with the residual hydrogen discharge switch, and the voltage sensor is used to detect the bus voltage. The residual hydrogen discharge switch is connected in series with the current sensor, and the current sensor is used to detect the output current of the fuel cell stack and the net output current of the fuel-electric system. The protector is connected in parallel with the residual hydrogen discharge switch, and the protector is connected in series with the integrated air compressor controller.

[0013] In one embodiment of the present invention, the fuel cell module further comprises a fuel cell control unit:

[0014] The fuel cell control unit is used to calculate the stack power based on the bus voltage and the stack output current; the fuel cell unit is also used to calculate the fuel-electric system power based on the bus voltage and the net output current of the fuel-electric system; the fuel cell unit is also used to transmit the stack power and the fuel-electric system power to the vehicle CAN network.

[0015] In one embodiment of the present invention, the fuel cell control unit is further used to detect whether the bus voltage is higher than a preset safety threshold when the fuel cell system without a DC converter is shut down. The fuel cell control unit is also used to close the residual hydrogen discharge switch when the bus voltage is lower than the preset safety threshold until the bus voltage is lower than the preset safety threshold.

[0016] In one embodiment of the present invention, the bidirectional DCDC unit includes: a power device and a high-frequency inductor;

[0017] The power device is connected in series with the high-frequency inductor, and the power device is used to step up or step down the bus voltage; the high-frequency inductor is used to convert the acquired voltage to obtain output power.

[0018] In one embodiment of the present invention, the power device comprises: a first power device and a second power device;

[0019] The first power device and the second power device are connected in series, and when the bus voltage is greater than the target voltage, the power device steps down the bus voltage, the first power device is turned on, and the second power device is turned off.

[0020] In one embodiment of the present invention, when the bus voltage is less than the target voltage, the power device boosts the bus voltage, the first power device is turned off, and the second power device is turned on.

[0021] In one embodiment of the present invention, the bidirectional DCDC unit further comprises: a pre-charge branch relay, a main positive relay, a pre-charge relay and a pre-charge resistor;

[0022] The pre-charging branch relay is connected in parallel with the main positive relay, which is in series with the pre-charging resistor, which is in series with the pre-charging relay. The pre-charging branch relay and the pre-charging resistor are used to limit the size of the charging current flowing into the capacitor. The main positive relay is connected in series with the pre-charging relay. The main positive relay is used to provide current to the fuel cell system without a DC converter when the capacitor is fully charged, and the pre-charging relay is used to provide a path for the pre-charging current of the capacitor.

[0023] In one embodiment of the present invention, when the bus voltage is less than a preset voltage, the pre-charging branch relay and the pre-charging relay are both closed to form a pre-charging loop;

[0024] When the bus voltage is greater than or equal to a preset voltage, the pre-charging branch relay is disconnected and the main positive relay is closed to provide current to the fuel cell system without a DC converter.

[0025] In summary, a fuel cell system without a DC converter in an embodiment of the present application includes: a fuel cell module, the fuel cell module is used to generate electrical energy; a vehicle power module, the vehicle power module includes a first high-voltage distribution unit, a bidirectional DCDC unit and an energy storage unit, the first high-voltage distribution unit is used to obtain the electrical energy, and the bidirectional DCDC unit is used to realize the energy conversion between the first high-voltage distribution unit and the energy storage unit. By directly connecting the output of the battery stack to the second high-voltage distribution unit, and installing a 50KW bidirectional DCDC unit between the first high-voltage distribution unit and the energy storage unit, the bidirectional DCDC unit is mainly used for energy conversion between the energy storage unit and the first high-voltage distribution unit. When the bus voltage is too high, the voltage can be reduced to charge the energy storage unit. When the bus voltage is too low, the voltage can be reversed to provide voltage to the bus, so as to reduce the dependence of the fuel cell system on DCDC and the dependence of the vehicle on the power battery.

[0026] The fuel cell system without DC converter proposed in the present application, other advantages, objectives and features of the present application will be reflected in part through the following description, and in part will be understood by technicians in this field through research and practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present specification. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0028] Figure 1 A schematic diagram of the structure of a fuel cell system without a DC converter provided in an embodiment of the present application;

[0029] Figure 2 A schematic structural diagram of a first high-voltage power distribution unit in a fuel cell system without a DC converter provided in an embodiment of the present application;

[0030] Figure 3 A schematic structural diagram of a second high-voltage power distribution unit in a fuel cell system structure without a DC converter provided in an embodiment of the present application;

[0031] Figure 4 A schematic structural diagram of a bidirectional DCDC unit in a fuel cell system structure without a DC converter provided in an embodiment of the present application;

[0032] in, Figure 1-Figure 4 The corresponding relationship between the reference numerals and the component names is as follows:

[0033] 101 fuel cell module, 1011 fuel cell stack, 1012 second high-voltage distribution unit, 10121 residual hydrogen discharge switch, 10122 voltage sensor, 10123 current sensor, 10124 protector, 10125 integrated air compressor controller, 1013 fuel cell control unit, 201 vehicle power module, 2011 first high-voltage distribution unit, 2012 bidirectional DCDC unit, 20121 power device, 201211 first power device, 201212 second power device, 20122 high-frequency inductor, 20123 pre-charge branch relay, 20124 main positive relay, 20125 pre-charge relay, 20126 pre-charge resistor, 2013 energy storage unit. DETAILED DESCRIPTION

[0034] In order to better understand the technical solutions provided by the embodiments of this specification, the technical solutions of the embodiments of this specification are described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of this specification and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this specification, rather than limitations on the technical solutions of this specification. In the absence of conflict, the embodiments of this specification and the technical features in the embodiments can be combined with each other.

[0035] In this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements limited by the statement "comprise one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. The term "more than two" includes two or more than two situations.

[0036] See also Figure 1 , is a schematic diagram of a fuel cell system structure without a DC converter provided in an embodiment of the present application, which may specifically include:

[0037] A fuel cell module 101, wherein the fuel cell module 101 is used to generate electrical energy;

[0038] The vehicle power module 201 includes a first high-voltage distribution unit 2011, a bidirectional DCDC unit 2012 and an energy storage unit 2013. The first high-voltage distribution unit 2011 is used to obtain the electric energy, and the bidirectional DCDC unit 2012 is used to realize energy conversion between the first high-voltage distribution unit 2011 and the energy storage unit 2013.

[0039] For example, Figure 2As shown, it is a structural schematic diagram of the first high-voltage distribution unit in a fuel cell system structure without a DC converter provided in an embodiment of the present application, and the function of the fuel cell module 101 is to generate electrical energy. It is a device that directly converts the chemical energy of a fuel (such as hydrogen) and an oxidant (such as oxygen) into electrical energy. It generates current through an electrochemical reaction to provide a source of electricity for the entire system. The bidirectional DCDC unit 2012 can realize energy conversion between the first high-voltage distribution unit 2011 and the energy storage unit 2013. When the output power of the fuel cell module 101 is greater than the vehicle demand, the bidirectional DCDC unit 2012 can store excess energy in the energy storage unit 2013, for example, converting high-voltage direct current into a voltage and current suitable for charging the energy storage unit 213. When the output power of the fuel cell module 101 is insufficient, the bidirectional DCDC unit 2012 can extract energy from the energy storage unit 2013 and supplement it to the vehicle power system to meet the power demand of the vehicle. The energy storage unit 2013 is usually a power battery or a supercapacitor, which can provide additional energy when the fuel cell output power is insufficient to improve the power performance and cruising range of the vehicle. In cases such as braking energy recovery, the energy storage unit 2013 can also store the recovered energy to improve energy utilization efficiency.

[0040] In summary, the fuel cell system without DC converter proposed in the embodiment of the present application directly connects the output of the battery stack 1011 to the second high-voltage distribution unit 1012, and installs a 50KW bidirectional DCDC unit 2012 between the first high-voltage distribution unit 2011 and the energy storage unit 2013. The bidirectional DCDC unit 2012 is mainly used for energy conversion between the energy storage unit 2013 and the first high-voltage distribution unit 2011. When the bus voltage is too high, it can step down the voltage to charge the energy storage unit 2013. When the bus voltage is too low, it can reversely step up the voltage to provide voltage to the bus, thereby achieving the purpose of reducing the fuel cell system's dependence on DCDC and the vehicle's dependence on the power battery.

[0041] In some examples, the fuel cell module 101 includes: a fuel cell stack 1011 and a second high-voltage power distribution unit 1012;

[0042] The fuel cell stack 1011 is used to obtain chemical energy from fuel and convert the chemical energy into electrical energy according to electrochemical reaction;

[0043] The second high-voltage power distribution unit 1012 is used to distribute the electric energy.

[0044] Exemplarily, the stack 1011 is the core component of the fuel cell module 101. It obtains chemical energy from fuel (usually hydrogen). Through electrochemical reactions, the chemical energy is directly converted into electrical energy. The second high-voltage distribution unit 1012 is used to distribute the electrical energy generated by the stack 1011. The electrical energy is distributed to different loads or systems, for example, to the main drive motor, DCL, air conditioning, PTC (abbreviation of Positive Temperature Coefficient, generally refers to positive temperature coefficient thermistor, commonly used in heating devices) and other high-voltage components to meet the power requirements of the fuel cell module 101 itself and other systems connected.

[0045] In some examples, the second high-voltage power distribution unit 1012 includes: a residual hydrogen discharge switch 10121, a voltage sensor 10122, a current sensor 10123, a protector 10124 and an integrated air compressor controller 10125;

[0046] The voltage sensor 10122 is connected in parallel with the residual hydrogen discharge switch 10121, and the voltage sensor 10122 is used to detect the bus voltage. The residual hydrogen discharge switch 10121 is connected in series with the current sensor 10123, and the current sensor 10123 is used to detect the output current of the fuel cell stack and the net output current of the fuel-electric system. The protector 10124 is connected in parallel with the residual hydrogen discharge switch 10121, and the protector 10124 is connected in series with the integrated air compressor controller 10125.

[0047] For example, Figure 3 As shown, this is a schematic diagram of the structure of the second high-voltage distribution unit in a fuel cell system without a DC converter proposed in the present application, and the voltage sensor 10122 is used to detect the bus voltage, that is, the voltage of the main power supply line in the circuit. The residual hydrogen discharge switch 10121 is used to control the discharge process of excess hydrogen in the fuel cell. When the excess hydrogen needs to be released, the switch is closed so that the hydrogen can be safely discharged to prevent the safety risks caused by hydrogen accumulation. The current sensor 10123 is used to detect the output current of the battery stack and the net output current of the fuel-electric system. By monitoring the current, the working status of the battery stack 1011 and the power output of the entire fuel-electric system can be understood, which is helpful for controlling and diagnosing faults in the system. The protector 10124 can play a role in protecting the circuit, for example, when the current is too large, the voltage is too high, or other abnormal conditions occur, the circuit is cut off to protect other components in the system from damage.

[0048] In some examples, the fuel cell module 101 further includes a fuel cell control unit 1013:

[0049] The fuel cell control unit 1013 is used to calculate the stack power based on the bus voltage and the stack output current; the fuel cell unit is also used to calculate the fuel-electric system power based on the bus voltage and the net output current of the fuel-electric system; the fuel cell unit is also used to transmit the stack power and the fuel-electric system power to the vehicle CAN network.

[0050] Exemplarily, the FCCU (Fuel Cell Control Unit, fuel cell control unit 1013) uses a voltage sensor 10122 to monitor the bus voltage. The bus is the main line for power transmission. Detecting the bus voltage can understand the power supply situation of the entire system and ensure that the voltage is within a suitable range to ensure the normal operation of the fuel cell system and other devices connected thereto. The fuel cell control unit 1013 detects the stack output current and the net output current of the fuel-electric system respectively with the help of the current sensor 10123. By monitoring these current parameters, the working state of the stack 1011 and the power output of the entire fuel-electric system can be mastered, providing an important basis for the control and management of the system. The fuel cell control unit 1013 calculates the stack power (stack power = bus voltage × stack output current) based on the detected bus voltage and stack output current and other parameters. At the same time, the power of the entire fuel-electric system is calculated in combination with the bus voltage and the net output current of the fuel-electric system. Then, the FCCU uploads the stack power and fuel-electric system power to the vehicle's CAN network (Controller Area Network), allowing other control units and systems of the vehicle to obtain the operating status information of the fuel cell system for comprehensive coordination and control.

[0051] In some examples, the fuel cell control unit 1013 is also used to detect whether the bus voltage is higher than a preset safety threshold when the fuel cell system without a DC converter is shut down. The fuel cell control unit is also used to close the residual hydrogen discharge switch 10121 when the bus voltage is lower than the preset safety threshold until the bus voltage is lower than the preset safety threshold.

[0052] Exemplarily, when the fuel cell system completes shutdown, the FCCU will continue to detect the bus voltage through the voltage sensor 10122. If the bus voltage is detected to be higher than the preset safety threshold, where the preset safety threshold is 60V, the FCCU will take measures to reduce the voltage to ensure safety. The specific operation is to close the residual hydrogen discharge switch 10121. When the residual hydrogen discharge switch 10121 is closed, the voltage generated by the residual hydrogen reaction inside the system will be discharged through the resistor. Through this discharge process, the bus voltage is reduced to below the safe voltage of 60V. The purpose of this is to avoid safety risks caused by excessive voltage due to residual hydrogen reaction after the system is shut down, such as electrical failures, fires, and even explosions. Lowering the voltage to a safe range can improve the safety and stability of the system.

[0053] In some examples, the bidirectional DCDC unit 2012 includes: a power device 20121 and a high-frequency inductor 20122;

[0054] The power device 20121 is connected in series with the high-frequency inductor 20122. The power device 20121 is used to step up or step down the bus voltage; the high-frequency inductor 20122 is used to convert the acquired voltage to obtain output power.

[0055] For example, Figure 4 As shown, it is a structural schematic diagram of a bidirectional DCDC unit in a fuel cell system structure without a DC converter provided in an embodiment of the present application. The main function of the bidirectional DCDC unit 2012 is to clamp the bus voltage, according to the accelerator pedal of the whole vehicle (which can be understood as power demand), and then set the target operating voltage according to the polarization curve of the working of the battery stack 1011. At this voltage, the battery stack 1011 can output the corresponding power. The power device 20121 is used to boost or buck the bus voltage. When a higher voltage is required to drive a specific load or perform energy transmission, the power device 20121 can increase the bus voltage; and when the voltage needs to be reduced to adapt to different circuit or equipment requirements, it can perform a buck operation. The high-frequency inductor 20122 is used to convert the acquired voltage to obtain the output power. When the current passes through the high-frequency inductor 20122, the voltage will be transformed according to its characteristics. This transformation may include functions such as filtering, energy storage and voltage conversion. Through the action of the high-frequency inductor 20122, the input voltage is converted into an output power suitable for a specific load or system requirement.

[0056] In some examples, the power device 20121 includes: a first power device 201211 and a second power device 201212;

[0057] The first power device 201211 and the second power device 201212 are connected in series. When the bus voltage is greater than the target voltage, the power device 20121 steps down the bus voltage, the first power device 201211 is turned on and the second power device 201212 is turned off.

[0058] Exemplarily, when the bus voltage is greater than the target voltage, the bus voltage needs to be stepped down. At this time, the power device 20121 plays a step-down role. Specifically, the first power device 201211 is turned on, and the second power device 201212 is turned off. In this way, the bus voltage can be stepped down to make the output voltage closer to the target voltage to meet the needs of the system.

[0059] In some examples, when the bus voltage is less than a target voltage, the power device 20121 boosts the bus voltage, the first power device 201211 is turned off, and the second power device 201212 is turned on.

[0060] Exemplarily, when the bus voltage is less than the target voltage, the bus voltage needs to be boosted to reach the desired target voltage value. At this time, the power device 20121 performs a voltage boost. Specifically, the first power device 201211 is turned off and the second power device 201212 is turned on. In this way, when the bus voltage is insufficient, the working state of the power device 20121 can be adjusted to achieve a boost regulation of the bus voltage, ensuring that the output voltage meets the system requirements.

[0061] In some examples, the bidirectional DCDC unit 2012 further includes: a pre-charge branch relay 20123, a main positive relay 20124, a pre-charge relay 20125 and a pre-charge resistor 20126;

[0062] The pre-charging branch relay 20123 is connected in parallel with the main positive relay 20124, which is connected in series with the pre-charging resistor 20126, which is connected in series with the pre-charging relay 20125. The pre-charging branch relay 20123 and the pre-charging resistor 20126 are used to limit the size of the charging current flowing into the capacitor, and the main positive relay 20124 is connected in series with the pre-charging relay 20125. The main positive relay 20124 is used to provide current to the fuel cell system without a DC converter when the capacitor is fully charged, and the pre-charging relay 20125 is used to provide a path for the pre-charging current of the capacitor.

[0063] Exemplarily, the pre-charge branch relay 20123 is connected in parallel with the main positive relay 20124. The pre-charge branch relay 20123 is connected in series with the pre-charge resistor 20126, and the pre-charge resistor 20126 is further connected in series with the pre-charge relay 20125. At the same time, the main positive relay 20124 is also connected in series with the pre-charge relay 20125.

[0064] The function of the pre-charging branch relay 20123 and the pre-charging resistor 20126 is to limit the size of the charging current flowing into the capacitor. At the initial stage of circuit startup, the capacitor is equivalent to a short-circuit state. If it is directly connected to the power supply, a large impact current may be generated, damaging the circuit components. The series connection of the pre-charging branch relay 20123 and the pre-charging resistor 20126 can limit the charging current, causing it to rise slowly, thereby protecting the circuit.

[0065] The main positive relay 20124 is used to provide current to the fuel cell system without a DC converter when the capacitor is fully charged. When the capacitor is charged to a certain level and meets the system requirements, the main positive relay 20124 closes to provide a large current path required for normal operation.

[0066] The pre-charging relay 20125 is used to provide a path for the pre-charging current of the capacitor. In the pre-charging stage, the pre-charging relay 20125 is closed, so that the current flows into the capacitor through the pre-charging branch relay 20123 and the pre-charging resistor 20126 for charging.

[0067] In some examples, when the bus voltage is less than a preset voltage, the pre-charging branch relay 20123 and the pre-charging relay 20125 are both closed to form a pre-charging loop;

[0068] When the bus voltage is greater than or equal to a preset voltage, the pre-charging branch relay 20123 is disconnected and the main positive relay 20124 is closed to provide current to the fuel cell system without a DC converter.

[0069] Exemplarily, when the bus voltage is less than the preset voltage, the pre-charging branch relay 20123 and the pre-charging relay 20125 are both closed. At this time, a pre-charging loop is formed, the purpose of which is to slowly charge components such as capacitors through the loop, because under low voltage conditions, direct access to the main loop may generate a large impact current and damage system components. The pre-charging resistor 20126 in the pre-charging loop can limit the size of the charging current to ensure a safe and stable charging process.

[0070] The pre-charging branch relay 20123 is disconnected, and the main positive relay 20124 is closed. At this time, the pre-charging branch is disconnected, and the main positive relay 20124 provides current to the fuel cell system without a DC converter. Because when the bus voltage reaches the preset value, it means that components such as capacitors have been charged to a suitable state and can be switched to the main circuit for normal operation. After the main positive relay 20124 is closed, it can provide a larger current path to meet the needs of normal operation of the system.

[0071] In the present disclosure, the terms "first", "second", and "third" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance; the term "plurality" refers to two or more, unless otherwise expressly defined. The terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to the specific circumstances.

[0072] In the description of the present disclosure, it is necessary to understand that the directions or positional relationships indicated by the terms "up", "down", "left", "right", "front", "back", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation, and therefore, should not be understood as a limitation on the present disclosure.

[0073] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0074] In the several embodiments provided in the present application, it should be understood that the disclosed devices, apparatuses and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0075] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0076] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0077] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), disk or optical disk and other media that can store program codes.

[0078] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

[0079] Although the preferred embodiments of this specification have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of this specification.

[0080] Obviously, those skilled in the art can make various changes and modifications to this specification without departing from the spirit and scope of this specification. Thus, if these modifications and variations of this specification fall within the scope of the claims of this specification and their equivalents, this specification is also intended to include these modifications and variations.

Claims

1. A fuel cell system without a DC converter, characterized in that: The system comprises: A fuel cell module, wherein the fuel cell module is used to generate electrical energy; A vehicle power module, the vehicle power module includes a first high-voltage distribution unit, a bidirectional DCDC unit and an energy storage unit, the first high-voltage distribution unit is used to obtain the electric energy, and the bidirectional DCDC unit is used to realize energy conversion between the first high-voltage distribution unit and the energy storage unit.

2. A fuel cell system without a DC converter according to claim 1, characterized in that: The fuel cell module comprises: a fuel cell stack and a second high-voltage power distribution unit; The fuel cell stack is used to obtain chemical energy from fuel and convert the chemical energy into electrical energy according to electrochemical reaction; The second high-voltage power distribution unit is used to distribute the electric energy.

3. A fuel cell system without a DC converter according to claim 1, characterized in that: The second high-voltage power distribution unit includes: a residual hydrogen discharge switch, a voltage sensor, a current sensor, a protector and an integrated air compressor controller; The voltage sensor is connected in parallel with the residual hydrogen discharge switch, and the voltage sensor is used to detect the bus voltage. The residual hydrogen discharge switch is connected in series with the current sensor, and the current sensor is used to detect the output current of the fuel cell stack and the net output current of the fuel-electric system. The protector is connected in parallel with the residual hydrogen discharge switch, and the protector is connected in series with the integrated air compressor controller.

4. A fuel cell system without a DC converter according to claim 3, characterized in that: The fuel cell module further comprises a fuel cell control unit: The fuel cell control unit is used to calculate the stack power based on the bus voltage and the stack output current; the fuel cell unit is also used to calculate the fuel-electric system power based on the bus voltage and the net output current of the fuel-electric system; the fuel cell unit is also used to transmit the stack power and the fuel-electric system power to the vehicle CAN network.

5. A fuel cell system without a DC converter according to claim 4, characterized in that: The fuel cell control unit is also used to detect whether the bus voltage is higher than a preset safety threshold when the fuel cell system without a DC converter is shut down. The fuel cell control unit is also used to close the residual hydrogen discharge switch when the bus voltage is lower than the preset safety threshold until the bus voltage is lower than the preset safety threshold.

6. A fuel cell system without a DC converter according to claim 3, characterized in that: The bidirectional DCDC unit includes: a power device and a high-frequency inductor; The power device is connected in series with the high-frequency inductor, and the power device is used to step up or step down the bus voltage; the high-frequency inductor is used to convert the acquired voltage to obtain output power.

7. A fuel cell system without a DC converter according to claim 6, characterized in that: The power device comprises: a first power device and a second power device; The first power device and the second power device are connected in series, and when the bus voltage is greater than the target voltage, the power device steps down the bus voltage, the first power device is turned on, and the second power device is turned off.

8. A fuel cell system without a DC converter according to claim 7, characterized in that: When the bus voltage is less than the target voltage, the power device boosts the bus voltage, the first power device is turned off, and the second power device is turned on.

9. A fuel cell system without a DC converter according to claim 6, characterized in that: The bidirectional DCDC unit also includes: a pre-charge branch relay, a main positive relay, a pre-charge relay and a pre-charge resistor; The pre-charging branch relay is connected in parallel with the main positive relay, which is in series with the pre-charging resistor, which is in series with the pre-charging relay. The pre-charging branch relay and the pre-charging resistor are used to limit the size of the charging current flowing into the capacitor. The main positive relay is connected in series with the pre-charging relay. The main positive relay is used to provide current to the fuel cell system without a DC converter when the capacitor is fully charged, and the pre-charging relay is used to provide a path for the pre-charging current of the capacitor.

10. A fuel cell system without a DC converter according to claim 9, characterized in that: When the bus voltage is less than a preset voltage, the pre-charging branch relay and the pre-charging relay are both closed to form a pre-charging circuit; When the bus voltage is greater than or equal to a preset voltage, the pre-charging branch relay is disconnected and the main positive relay is closed to provide current to the fuel cell system without a DC converter.

Images