Fuel cell power generation system

Abstract

The invention provides a fuel cell power generation system. The fuel cell power generation system comprises a fuel cell, a three-phase inverter circuit and a three-phase transformer, and each phase of inverter circuit of the three-phase inverter circuit comprises at least one H-bridge inverter. And the input end of the three-phase inverter circuit is connected with the fuel cell. The three-phase transformer comprises a three-phase primary winding and a three-phase secondary winding, the three-phase output ends of the three-phase inverter circuit are connected with the three-phase secondary winding in a one-to-one correspondence mode, and the three-phase primary winding is used for outputting electric energy. The number of circuit elements of the fuel cell power generation system can be reduced, the switching loss is reduced, and the operation efficiency of the circuit is improved.

Description

Technical Field

[0001] The present application relates to the field of battery power generation technology, and in particular to a fuel cell power generation system. Background Art

[0002] Large-scale fuel cell power generation systems usually include many stacks. The voltage output by the stack is converted to low-voltage AC power after DC / DC conversion and DC / AC inversion, and then connected to the distribution network through a transformer. DC / AC inversion is mostly achieved through a three-phase bridge circuit, which has many circuit components, complex circuits, and high integration difficulty. In order to ensure a smooth output waveform of the AC voltage, the three-phase bridge circuit needs to use a sufficiently high switching frequency, which results in high switching losses and low circuit efficiency. Summary of the invention

[0003] The present application provides a fuel cell power generation system, which can reduce the number of circuit elements, reduce switching losses, and improve the operating efficiency of the circuit.

[0004] The present application provides a fuel cell power generation system, comprising:

[0005] Fuel cells;

[0006] A three-phase inverter circuit, each phase of the inverter circuit includes at least one H-bridge inverter, and an input end of the three-phase inverter circuit is connected to the fuel cell; and

[0007] The three-phase transformer comprises a three-phase primary winding and a three-phase secondary winding. The three-phase output end of the three-phase inverter circuit is connected to the three-phase secondary winding in a one-to-one correspondence. The three-phase primary winding is used to output electric energy.

[0008] Optionally, each phase inverter circuit of the three-phase inverter circuit includes a plurality of H-bridge inverters connected in parallel.

[0009] Optionally, the fuel cell power generation system further includes a DC-DC converter, wherein an input end of the DC-DC converter is connected to the fuel cell, and an output end of the DC-DC converter is connected to an input end of the three-phase inverter circuit.

[0010] Optionally, the fuel cell power generation system includes a plurality of the fuel cells and a plurality of the DC-DC converters, and an input end of each of the DC-DC converters is connected to one of the fuel cells, respectively.

[0011] Optionally, the fuel cell power generation system further includes a low-voltage DC bus, the output ends of the plurality of DC-DC converters are connected in parallel to the low-voltage DC bus, and the input end of the three-phase inverter circuit is connected to the low-voltage DC bus.

[0012] Optionally, the number of the H-bridge inverters in each phase of the inverter circuit is determined according to the capacity of the fuel cell power generation system, the rated voltage of the low-voltage DC bus and the model of the H-bridge inverter.

[0013] Optionally, the fuel cell power generation system further includes an energy storage battery connected to the low-voltage DC bus.

[0014] Optionally, the DC-DC converter includes a Boost circuit.

[0015] Optionally, the number of the H-bridge inverters in the three-phase inverter circuit is equal.

[0016] Optionally, each phase of the three-phase transformer includes a plurality of secondary windings, which are respectively connected one-to-one with the output ends of a plurality of H-bridge inverters of the inverter circuit of each phase.

[0017] In some embodiments, the input end of the three-phase inverter circuit is connected to the fuel cell, each phase inverter circuit includes at least one H-bridge inverter, the three-phase output end of the three-phase inverter circuit is connected one-to-one with the three-phase secondary winding of the three-phase transformer, and the three-phase primary winding is used to output electrical energy. The H-bridge inverter has a small number of circuit elements and a simple circuit, and only needs to adopt a lower switching frequency to achieve a higher equivalent switching frequency, thereby reducing switching losses and improving the operating efficiency of the circuit.

[0018] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0020] Figure 1 Shown is a circuit diagram of an embodiment of a fuel cell power generation system of the present application. DETAILED DESCRIPTION

[0021] The present application provides a fuel cell power generation system. The fuel cell power generation system of the present application is described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the features of the following embodiments and implementations can be combined with each other.

[0022] Figure 1 FIG. 1 is a circuit diagram of an embodiment of a fuel cell power generation system 10 of the present application. Figure 1 As shown, the fuel cell power generation system 10 includes: a fuel cell 11 , a three-phase inverter circuit 12 and a three-phase transformer 13 .

[0023] The fuel cell power generation system 10 can convert the DC power generated by the fuel cell 11 into AC power suitable for use by a power grid or a specific load.

[0024] The fuel cell 11 can convert the chemical energy of the fuel and the oxidant into electrical energy through an electrochemical reaction. In some embodiments, the fuel cell 11 includes a hydrogen fuel cell. The hydrogen fuel cell converts the chemical energy of hydrogen and oxygen into electrical energy.

[0025] Each phase of the three-phase inverter circuit 12 includes at least one H-bridge inverter 121. The input end of the three-phase inverter circuit 12 is connected to the fuel cell 11.

[0026] The three-phase inverter circuit 12 is used to convert the direct current generated by the fuel cell 11 into alternating current. The H-bridge inverter 121 includes four switching elements Q1, Q2, Q3 and Q4, and the four switching elements Q1, Q2, Q3 and Q4 are arranged in an H-type to form two parallel branches and an input-output branch. In some embodiments, the switching elements include MOSFET, IGBT, etc. In some embodiments, the H-bridge inverter 121 also includes a freewheeling diode connected in parallel with the switching element to protect the switching element. By controlling the on and off of the switching elements Q1, Q2, Q3 and Q4, the direct current is inverted into alternating current. Specifically, the switching elements Q1 and Q4 are controlled to be turned on, and the switching elements Q2 and Q3 are turned off at the same time. At this time, the current flows from the output end of the fuel cell 11 through the switching element Q1 to the switching element Q4. Then the switching elements Q2 and Q3 are controlled to be turned on, and the switching elements Q1 and Q4 are turned off at the same time, and the current flows from the output end of the fuel cell 11 through the switching element Q2 to the switching element Q3. In the three-phase inverter circuit 12 , the H-bridge inverter 121 of each phase of the inverter circuit generates an alternating current of one phase.

[0027] The three-phase transformer 13 includes a three-phase primary winding 131 and a three-phase secondary winding 132. The three-phase output terminals of the three-phase inverter circuit 12 are connected one-to-one with the three-phase secondary windings 132. The three-phase primary winding 131 is used to output electric energy.

[0028] The three-phase transformer 13 is used to adjust the voltage level of the alternating current. The three-phase alternating current output by the three-phase inverter circuit 12 is first connected to the three-phase secondary winding 132. The three-phase secondary winding 132 plays the role of electrical isolation and voltage conversion, and adjusts the voltage output by the three-phase inverter circuit 12 to a range suitable for the use of the power grid or load. The alternating current transformed by the three-phase secondary winding 132 is then output from the three-phase primary winding 131. At this time, the output electric energy has met the specific voltage and current requirements and can be directly supplied to the power grid or a specific load for use.

[0029] In some embodiments, the input end of the three-phase inverter circuit 12 is connected to the fuel cell 11, each phase inverter circuit includes at least one H-bridge inverter 121, the three-phase output end of the three-phase inverter circuit 12 is connected to the three-phase secondary winding 132 of the three-phase transformer 13 in a one-to-one correspondence, and the three-phase primary winding 131 is used to output electric energy. At least one H-bridge inverter 121 of each phase inverter circuit can utilize the leakage reactance of the three-phase transformer 13, and run in parallel through the single-phase winding of the three-phase transformer 13, thereby eliminating the connection reactor required when the H-bridge inverter 121 is directly connected in parallel, making the system more compact, the number of circuit elements of the H-bridge inverter 121 is small, and the circuit is simple. Since the sum of the voltages of the single-phase windings on the secondary side of the three-phase transformer 13 is relatively high, for the scenario where a large capacity of fuel cell power generation is required, the current of the three-phase transformer 13 is relatively small, the design of the three-phase inverter circuit 12 is relatively simple, and the increase in cable and transformer losses is also avoided.

[0030] In some embodiments, each phase inverter circuit of the three-phase inverter circuit 12 includes a plurality of H-bridge inverters 121 connected in parallel. Since the plurality of H-bridge inverters 121 work in parallel, they can jointly bear a larger current load.

[0031] If the switching frequency of the switching elements in the three-phase inverter circuit 12 is f sw , then the equivalent switching frequency of each H-bridge inverter 121 is 2f sw When the carrier phase shift pulse width modulation strategy is adopted for n H-bridge inverters 121, the overall equivalent switching frequency is 2nf sw In this way, only a lower switching frequency is needed to achieve a higher equivalent switching frequency, reduce switching losses, and improve the operating efficiency of the fuel cell power generation system 10.

[0032] Each phase of the three-phase transformer 13 includes a plurality of secondary windings, which are respectively connected to the output ends of the plurality of H-bridge inverters 121 of the inverter circuit of each phase in a one-to-one correspondence.

[0033] Since the output of each H-bridge inverter 121 is directly connected to a secondary winding of a corresponding phase of the three-phase transformer 13, the output of each H-bridge inverter 121 can be independently controlled. Therefore, the output voltage and current of each H-bridge inverter 121 can be flexibly adjusted according to system requirements or load changes, thereby improving the overall power conversion efficiency.

[0034] The multiple secondary windings are connected to the output ends of the multiple H-bridge inverters 121 of each phase inverter circuit in a one-to-one manner, which reduces the energy loss in the power conversion process and makes the system more efficient.

[0035] When a certain H-bridge inverter 121 or a secondary winding fails, since they are connected in a one-to-one relationship, it is easier to isolate the fault, thereby reducing the impact of the fault on the entire system and improving the reliability and stability of the system.

[0036] In some implementations, an additional H-bridge inverter 121 and a secondary winding may be configured for each phase inverter circuit as redundancy. When a main inverter or a secondary winding fails, the redundant H-bridge inverter 121 and the secondary winding may immediately take over the work to ensure continuous operation of the system.

[0037] Such a connection mode enables the output of each H-bridge inverter 121 to be accurately matched to the corresponding secondary winding, which helps to reduce the voltage fluctuation, current imbalance and other problems caused by mismatch, thereby improving the power quality and stability of the system.

[0038] According to different application scenarios and requirements, the number of H-bridge inverters 121 and the configuration of the secondary winding in each phase inverter circuit can be flexibly adjusted. For example, in situations where a high output voltage is required, the number of H-bridge inverters 121 can be increased or the turns ratio of the secondary winding can be adjusted; in situations where a large current is required, the cross-sectional area of ​​the secondary winding can be increased.

[0039] Each phase of the three-phase transformer 13 includes multiple secondary windings, which are connected one-to-one with the output ends of multiple H-bridge inverters of each phase inverter circuit, thereby improving the efficiency of power conversion, enhancing the reliability of the system, optimizing the performance of the system, and providing flexible configuration options to meet different application requirements.

[0040] The primary winding of the three-phase transformer 13 includes a three-phase winding in a star connection.

[0041] The three-phase winding of the star connection can ensure that the three-phase current remains balanced in the system. In a three-phase power system, if the three-phase load is completely symmetrical, the current of each phase will also be equal. This balanced state helps to reduce the energy loss and potential overheating problems of the system. The star connection maintains this balanced state by providing a common neutral point so that the current of each phase can flow independently without being affected by other phases. The neutral point of the star connection can be grounded or ungrounded. In a system that requires grounding protection, neutral point grounding can effectively prevent electric shock hazards and improve the safety of the system. In addition, neutral point grounding can also provide a reference potential for the system, which is convenient for voltage measurement and protection control.

[0042] The star connection also helps reduce voltage fluctuations. In a three-phase system, if the load on a phase suddenly increases or decreases, it may cause fluctuations in the voltage of that phase. However, due to the existence of the star connection, the voltages of the other two phases can be compensated to a certain extent through the neutral point, thereby reducing the impact of voltage fluctuations on the entire system. In this way, the fuel cell power generation system 10 can maintain a stable output voltage to meet the load requirements.

[0043] The fuel cell power generation system 10 may need to supply power to various types of loads, including linear loads and nonlinear loads. The three-phase transformer 13 in star connection can better adapt to these different types of loads. For linear loads, it can provide stable voltage and current; for nonlinear loads, such as power electronic equipment, it can provide a certain degree of current compensation through the neutral point to reduce the generation of harmonics and the impact on the system.

[0044] The primary winding of the three-phase transformer 13 adopts a three-phase winding in star connection, which can improve the current balance of the system, reduce voltage fluctuations, provide neutral point grounding, and adapt to different loads.

[0045] The fuel cell power generation system 10 also includes a DC-DC converter 14. The input end of the DC-DC converter 14 is connected to the fuel cell 11, and the output end of the DC-DC converter 14 is connected to the input end of the three-phase inverter circuit 12. The DC-DC converter 14 is used to adjust the DC voltage output by the fuel cell 11. Since the output voltage of the fuel cell 11 may fluctuate under different working conditions, and the subsequent three-phase inverter circuit 12 has specific requirements for the input voltage, it is necessary to stabilize the voltage through the DC-DC converter 14 to ensure the stable operation of the fuel cell power generation system 10. The DC-DC converter 14 can also optimize the power conversion efficiency and improve the efficiency of the fuel cell power generation system 10 by reducing the loss in the power conversion process and adjusting the output power according to the power grid demand. The DC-DC converter 14 also has an electrical isolation function, which can protect the three-phase inverter circuit 12 of the subsequent stage from the influence of the previous stage circuit failure or abnormal voltage, thereby enhancing the safety and reliability of the fuel cell power generation system 10.

[0046] The DC-DC converter 14 in the fuel cell power generation system 10 receives the DC power output from the fuel cell 11 stack, and outputs stable DC power that meets the requirements of the subsequent three-phase inverter circuit 12 by adjusting the voltage and optimizing the power conversion process. After the inverter process, it is converted into three-phase AC power, which is finally supplied and connected to the power grid. In this way, the fuel cell power generation system 10 can efficiently and stably provide power to the outside.

[0047] In some embodiments, the DC-DC converter 14 includes a Boost circuit.

[0048] The boost circuit is a step-up DC-DC converter that can convert a lower DC input voltage into a higher DC output voltage. The boost circuit includes switch elements Q5, Q6, inductor L1, and capacitor C1. When the switch element Q6 is turned on, the input voltage charges the capacitor C1 through the inductor L1 and the switch element Q6. At this time, the inductor L1 absorbs energy and the current gradually increases. When the switch element Q6 is turned off, since the current of the inductor L1 cannot change suddenly, the inductor L1 will release the energy absorbed before, and charge the capacitor C1 together with the input voltage to maintain the stability of the output voltage.

[0049] The control of the switching elements Q5 and Q6 can be achieved through pulse width modulation (PWM). The PWM signal switches the on and off states of the switching elements Q5 and Q6 at a fixed frequency, and controls the output voltage by adjusting the duty cycle. The larger the duty cycle, the higher the output voltage; conversely, the lower it is.

[0050] The fuel cell power generation system 10 includes a plurality of fuel cells 11 and a plurality of DC-DC converters 14. The input end of each DC-DC converter 14 is connected to a fuel cell 11. In this way, the output of each fuel cell 11 can be independently converted to voltage, thereby improving the flexibility and reliability of the entire fuel cell power generation system 10. At the same time, by using a plurality of DC-DC converters 14 in parallel, a higher power output and more complex voltage regulation requirements can be achieved.

[0051] The fuel cell power generation system 10 further includes a low-voltage DC bus 15 . The output ends of the plurality of DC-DC converters 14 are connected in parallel to the low-voltage DC bus 15 , and the input end of the three-phase inverter circuit 12 is connected to the low-voltage DC bus 15 .

[0052] The low-voltage DC bus 15 can collect the output voltages of multiple DC-DC converters 14, and combine the DC power from different fuel cells 11 and DC-DC converters 14 into a unified DC voltage. In this way, when the output voltage and current of the fuel cell 11 fluctuate, they can be collected on the low-voltage DC bus 15 in the form of stable voltage and current after being adjusted by the DC-DC converter 14.

[0053] The low voltage DC bus 15 transmits electric energy to the three-phase inverter circuit 12. The energy storage of the low voltage DC bus 15 helps to stabilize the voltage and current of the entire fuel cell power generation system 10 and reduce system fluctuations caused by sudden load changes or output fluctuations of the fuel cell 11.

[0054] The number of H-bridge inverters 121 in each phase inverter circuit is determined according to the capacity of the fuel cell power generation system 10 , the rated voltage of the low-voltage DC bus 15 , and the model of the H-bridge inverter 121 .

[0055] In the fuel cell power generation system 10 , the number of H-bridge inverters 121 in each phase inverter circuit directly affects the output capacity, efficiency and reliability of the fuel cell power generation system 10 .

[0056] The capacity of the fuel cell power generation system 10 depends on the type, quantity and power requirements of the loads connected to the system. For example, if the system is used to drive a large AC motor, a higher output power is required.

[0057] According to the total power demand of the system, the power share that each phase inverter circuit needs to bear can be calculated.

[0058] The rated voltage of the low voltage DC bus 15 is also a factor that needs to be considered when designing the three-phase inverter circuit 12. The H-bridge inverter 121 needs to be able to operate normally within this voltage range, and a certain voltage fluctuation range also needs to be considered.

[0059] Different types of H-bridge inverters 121 have different requirements for input voltage. When selecting the type of inverter 121, it is necessary to ensure that its input voltage range matches the rated voltage of the low-voltage DC bus 15.

[0060] The number of H-bridge inverters 121 required for each phase inverter circuit can be preliminarily determined based on the power requirement of each phase inverter circuit and the rated power of the H-bridge inverter 121. For example, if each phase inverter circuit needs to output 100 kW of power, and the rated power of the selected H-bridge inverter 121 is 50 kW, at least two H-bridge inverters 121 are required for each phase inverter circuit.

[0061] In some embodiments, in order to improve the reliability and redundancy of the system, an additional H-bridge inverter 121 is added to each phase inverter circuit. In this way, even if a certain H-bridge inverter 121 fails, the system can still continue to operate, reducing the risk of system downtime caused by a single failure point.

[0062] When determining the number of H-bridge inverters 121, it is also necessary to consider economy and maintainability. Too many H-bridge inverters 121 will increase the complexity and cost of the system; while too few H-bridge inverters 121 may not meet the power requirements of the system or reduce the reliability of the system. Therefore, it is necessary to select a number of H-bridge inverters 121 that is economical, reasonable and easy to maintain while meeting the system requirements.

[0063] In some embodiments, the number of H-bridge inverters 121 of the three-phase inverter circuit is equal.

[0064] The equal number of H-bridge inverters 121 in the three-phase inverter circuit helps to achieve a balanced distribution of loads between the phases. In a three-phase or multi-phase system, load balance is an important factor in ensuring stable operation of the system. If there are too many or too few H-bridge inverters 121 in a phase inverter circuit, this phase may bear too much load, while other phases may be lightly loaded, thereby causing system imbalance and reduced efficiency.

[0065] In addition, by making the number of H-bridge inverters 121 in the three-phase inverter circuit equal, the harmonics generated by load imbalance can be reduced to a certain extent, thereby improving the power quality.

[0066] The equal number of H-bridge inverters 121 in the three-phase inverter circuit is conducive to the standardized design of the system, which means that unified standards and processes can be adopted in the design, manufacturing, installation and maintenance process to reduce complexity and cost.

[0067] When the number of H-bridge inverters 121 in all phase inverter circuits is the same, if a phase fails or needs maintenance, it is easier to find a replacement H-bridge inverter 121 or troubleshoot. In addition, since the design of each phase is the same, maintenance personnel can quickly become familiar with and master the maintenance skills of the system.

[0068] If an H-bridge inverter 121 in a phase inverter circuit fails, while the number of H-bridge inverters 121 in other phases is the same and they operate normally, the entire system can still maintain a certain output capacity, thereby reducing the impact on the overall operation of the system.

[0069] The fuel cell power generation system 10 further includes an energy storage battery 16 connected to the low-voltage DC bus 15 .

[0070] The energy storage battery 16 can store excess electrical energy and release it when needed to balance the mismatch between the output of the fuel cell power generation system 10 and the load demand. This is beneficial for stabilizing the output of the fuel cell power generation system 10 when there is a sudden load change or output fluctuation of the fuel cell 11.

[0071] The energy storage battery 16 has a fast response capability and can replenish or absorb electric energy in a short time, thereby stabilizing the voltage and frequency of the system and reducing system fluctuations caused by imbalance between supply and demand.

[0072] When the fuel cell 11 or other power generation equipment fails, the energy storage battery 16 can serve as a backup power source to continue to supply power to the system and ensure the continuous operation of the system.

[0073] Electric energy flows bidirectionally between the energy storage battery 16 and the low voltage DC bus 15. The energy storage battery 16 can not only release electric energy when the system needs it, but also receive and store electric energy when there is excess electric energy.

[0074] When the fuel cell power generation system 10 is running, the DC power generated by the fuel cell 11 is first adjusted and stabilized by the DC-DC converter 14, and then collected on the low-voltage DC bus 15. At the same time, the energy storage battery 16 is also connected to the low-voltage DC bus 15. According to the load demand of the fuel cell power generation system 10 and the output of the fuel cell 11, the energy storage battery 16 can automatically adjust its charge and discharge state to balance the supply and demand of the system. When the load demand increases, the energy storage battery 16 can release electrical energy to supplement the system output; when the load demand decreases or the fuel cell 11 outputs excess electricity, the energy storage battery 16 can receive and store excess electrical energy. In this way, the fuel cell power generation system 10 can achieve efficient, stable and reliable power supply.

[0075] The solution of the present application is described below through specific embodiments.

[0076] Taking a 4MW hydrogen fuel cell power generation system as an example, the system includes 20 hydrogen fuel cells with a capacity of 200kW, each of which is connected to 20 200kW DC / DC converters 14. The rated voltage of the low-voltage DC bus 15 is 600V. The rated current output by each DC / DC converter 14 is 333.3A. In the three-phase inverter circuit 12, the rated voltage inverted by each H-bridge inverter 121 is 400V, so the total current on the low-voltage side should be 3.333kA. Select an H-bridge inverter 121 with a rated parameter of 1.2kV / 600A, then each H-bridge inverter 121 can share a current of about 420A. In this way, each phase inverter circuit requires a total of 8 to 9 H-bridge inverters 121. In this embodiment, 9 are taken, so that in addition to providing 4MW of active power to the distribution network, it can also provide about 2MVar of reactive power at the same time. Therefore, the capacity of the three-phase transformer 13 is designed to be 4.5 MVA, each phase transformer includes 9 single-phase windings, the rated voltage of each winding is 400 V, and the transformation ratio of the three-phase transformer 13 is 9×400√3 V / 10 kV.

[0077] In order to assist the start and stop of the hydrogen fuel cell, the energy storage battery 16 is selected to have a peak power of 4 MW.

Claims

1. A fuel cell power generation system, characterized in that: include: Fuel cells; A three-phase inverter circuit, each phase inverter circuit includes at least one H-bridge inverter, and an input end of the three-phase inverter circuit is connected to the fuel cell; and The three-phase transformer comprises a three-phase primary winding and a three-phase secondary winding. The three-phase output end of the three-phase inverter circuit is connected to the three-phase secondary winding in a one-to-one correspondence. The three-phase primary winding is used to output electric energy.

2. The fuel cell power generation system according to claim 1, characterized in that: Each phase inverter circuit of the three-phase inverter circuit includes a plurality of H-bridge inverters connected in parallel.

3. The fuel cell power generation system according to claim 2, characterized in that: The fuel cell power generation system further includes a DC-DC converter, an input end of the DC-DC converter is connected to the fuel cell, and an output end of the DC-DC converter is connected to an input end of the three-phase inverter circuit.

4. The fuel cell power generation system according to claim 3, characterized in that: The fuel cell power generation system includes a plurality of the fuel cells and a plurality of the DC-DC converters, and an input end of each of the DC-DC converters is connected to one of the fuel cells.

5. The fuel cell power generation system according to claim 4, characterized in that: The fuel cell power generation system also includes a low-voltage DC bus, the output ends of the plurality of DC-DC converters are connected in parallel to the low-voltage DC bus, and the input end of the three-phase inverter circuit is connected to the low-voltage DC bus.

6. The fuel cell power generation system according to claim 5, characterized in that: The number of the H-bridge inverters of each phase of the inverter circuit is determined according to the capacity of the fuel cell power generation system, the rated voltage of the low-voltage DC bus and the model of the H-bridge inverter.

7. The fuel cell power generation system according to claim 5, characterized in that: The fuel cell power generation system also includes an energy storage battery connected to the low-voltage DC bus.

8. The fuel cell power generation system according to claim 3, characterized in that: The DC-DC converter includes a Boost circuit.

9. The fuel cell power generation system according to claim 2, characterized in that: The number of the H-bridge inverters in the three-phase inverter circuit is equal.

10. The fuel cell power generation system according to claim 1, characterized in that: Each phase of the three-phase transformer includes a plurality of secondary windings, which are respectively connected to the output ends of the plurality of H-bridge inverters of the inverter circuit of each phase in a one-to-one correspondence.

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