A regenerative braking energy feedback device and a power supply system

Abstract

The present invention discloses a regenerative braking energy feedback device and a power supply system. When the rail vehicle brakes, the first DC voltage of the DC bus of the rail vehicle is converted into the second DC voltage required by the DC power grid through M first energy feedback converters, and is converted into the second AC voltage required by the AC power grid through N second energy feedback converters and N grid transformers. Thus, it can be seen that the present invention can not only realize the feedback of regenerative braking energy to AC power grids with different voltage levels, but also feedback it to DC power grids with different voltage levels. The feedback form of the regenerative braking energy is more flexible and has stronger expandability.

Description

Technical Field

[0001] The present invention relates to the technical field of rail transit, and particularly to a regenerative braking energy feedback device and a power supply system. Background Art

[0002] With the continuous development of rail transit, when the traction motor of a rail vehicle is in the braking condition, a large amount of regenerative braking energy is generated. If it can be recycled, it has extremely high economic value and environmental protection value. In the prior art, the voltage of the DC bus connected to the traction motor is fed back to the AC power grid through a regenerative braking energy feedback device. Specifically, the regenerative braking energy feedback device includes an energy feedback converter and an energy feedback transformer. The energy feedback converter converts the DC voltage of the DC bus into a first AC voltage, and then the energy feedback transformer boosts the first AC voltage to obtain a second AC voltage, and then the second AC voltage is fed back to the AC power grid. However, the existing regenerative braking energy feedback device has a single feedback form and poor expandability. Summary of the Invention

[0003] The purpose of the present invention is to provide a regenerative braking energy feedback device and a power supply system, which can not only realize the feedback of regenerative braking energy to AC power grids with different voltage levels, but also feedback it to DC power grids with different voltage levels. The feedback form of the regenerative braking energy is more flexible and has stronger expandability.

[0004] To solve the above technical problems, the present invention provides a regenerative braking energy feedback device, including:

[0005] M first energy feedback converters, the input ends of the M first energy feedback converters are connected to the DC bus of the rail vehicle, and the output ends of the M first energy feedback converters are connected to M DC power grid ports, and are used for converting the first DC voltage of the DC bus into the second DC voltage required by the DC power grid, and feeding back the second DC voltage to the corresponding DC power grid through the M DC power grid ports, where M is a positive integer;

[0006] N second energy feedback converters, the input ends of the N second energy feedback converters are connected to the DC bus of the rail vehicle, and are used for converting the first DC voltage of the DC bus into a first AC voltage;

[0007] N grid transformers, the input ends of the N grid transformers are respectively connected to the output ends of the N second energy feedback converters in a one-to-one correspondence, and the output ends of the N grid transformers are respectively connected to N AC power grid ports in a one-to-one correspondence, and are used for converting the first AC voltage into the second AC voltage required by the AC power grid, and feeding back the second AC voltage to the corresponding AC power grid through the N AC power grid ports, where N is a positive integer.

[0008] Preferably, the first energy feedback converter includes:

[0009] A first H-bridge inverter module with its input terminal serving as the input terminal of the first energy feedback converter, configured to invert the first DC voltage of the DC bus to obtain a third AC voltage;

[0010] A first resonant module, where the first resonant module is connected in series with the primary winding of a first isolation transformer and the series circuit is connected to the output terminal of the first H-bridge inverter module, for generating resonance;

[0011] The first isolation transformer, for electrically isolating the third AC voltage;

[0012] A first H-bridge rectifier module with its input terminal connected to the secondary winding of the first isolation transformer and its output terminal serving as the output terminal of the first energy feedback converter, for rectifying the third AC voltage to obtain the second DC voltage.

[0013] Preferably, the second energy feedback converter includes:

[0014] A second H-bridge inverter module with its input terminal serving as the input terminal of the second energy feedback converter, configured to invert the first DC voltage of the DC bus to obtain a fourth AC voltage;

[0015] A second resonant module, where the second resonant module is connected in series with the primary winding of a second isolation transformer and the series circuit is connected to the output terminal of the second H-bridge inverter module, for generating resonance;

[0016] The second isolation transformer, for electrically isolating the fourth AC voltage;

[0017] A second capacitor;

[0018] A second H-bridge rectifier module with its input terminal connected to the secondary winding of the second isolation transformer and its output terminal connected to the input terminal of the four-quadrant module through the second capacitor, for rectifying the fourth AC voltage to obtain the third DC voltage;

[0019] The four-quadrant module with its output terminal serving as the output terminal of the second energy feedback converter, for inverting the third DC voltage to obtain the first AC voltage.

[0020] Preferably, the second resonant module includes a resonant inductor and a resonant capacitor, and the resonant inductor and the resonant capacitor are connected in series.

[0021] Preferably, the second energy feedback converter further includes a reactor. The input end of the reactor is connected to the output end of the four-quadrant module, and the output end of the reactor is connected to the grid transformer, for filtering the first AC voltage.

[0022] Preferably, it further includes a pre-charging module. The pre-charging module is arranged between the grid transformer and the second energy feedback converter, for pre-charging the second capacitor.

[0023] Preferably, the pre-charging module includes a resistor, a first circuit breaker and a second circuit breaker;

[0024] The first circuit breaker is connected in series with the resistor and then connected in parallel with the second circuit breaker, and one end of the two ends after parallel connection is used as the input end of the pre-charging module, and the other end is used as the output end of the pre-charging module;

[0025] The first circuit breaker is used to conduct when the pre-charging of the second capacitor starts and disconnect after the pre-charging is completed;

[0026] The second circuit breaker is used to disconnect when the pre-charging of the second capacitor starts and conduct after the pre-charging is completed.

[0027] Preferably, it further includes:

[0028] M third energy feedback converters. The M third energy feedback converters are connected in parallel with the M first energy feedback converters one by one, for converting the first DC voltage of the DC bus into the second DC voltage required by the DC grid, and feeding back the second DC voltage to the DC grid corresponding to the DC grid port through the M DC grid ports, where M is a positive integer.

[0029] Preferably, it further includes:

[0030] N fourth energy feedback converters. The N fourth energy feedback converters are connected in parallel with the N second energy feedback converters one by one, for converting the first DC voltage of the DC bus into the first AC voltage.

[0031] To solve the above technical problems, the present invention further provides a power supply system, including a traction transformer and a rectifier. The traction transformer is connected to the power supply grid of the rail vehicle, the rectifier is respectively connected to the traction transformer and the DC bus of the rail vehicle, and the power supply system further includes the above-mentioned regenerative braking energy feedback device.

[0032] The present invention discloses a regenerative braking energy feedback device and a power supply system, including M first energy feedback converters, which can convert the first DC voltage of the DC bus of a rail vehicle into the second DC voltage required by the DC power grid, and feedback the second DC voltage to the DC power grid corresponding to the DC power grid port one by one through M DC power grid ports, where M is a positive integer; N second energy feedback converters and N grid transformers. The N second energy feedback converters can convert the first DC voltage of the DC bus of the rail vehicle into a first AC voltage, and then the N grid transformers convert the first AC voltage into the second AC voltage required by the AC power grid, and feedback the second AC voltage to the AC power grid corresponding to the AC power grid port one by one through N AC power grid ports, where N is a positive integer.

[0033] In this application, when the rail vehicle brakes, the first DC voltage of the DC bus of the rail vehicle is converted into the second DC voltage required by the DC power grid through M first energy feedback converters, and into the second AC voltage required by the AC power grid through N second energy feedback converters and N grid transformers. This can not only realize the feedback of regenerative braking energy to AC power grids with different voltage levels, but also to DC power grids with different voltage levels. The feedback form of regenerative braking energy is more flexible and has stronger expandability. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the prior art and the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0035] Figure 1 It is a schematic structural diagram of a regenerative braking energy feedback device provided by the present invention;

[0036] Figure 2 It is a schematic structural diagram of another regenerative braking energy feedback device provided by the present invention;

[0037] Figure 3 It is a partial schematic structural diagram of a second energy feedback converter provided by the present invention;

[0038] Figure 4 It is a schematic structural diagram of a power supply system provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The core of the present invention is to provide a regenerative braking energy feedback device and a power supply system, which can not only realize the feedback of regenerative braking energy to AC power grids with different voltage levels, but also to DC power grids with different voltage levels. The feedback form of regenerative braking energy is more flexible and has stronger expandability.

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0041] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of a regenerative braking energy feedback device provided by this application.

[0042] The present invention provides a regenerative braking energy feedback device, including:

[0043] M first energy feedback converters 1, the input ends of the M first energy feedback converters 1 are connected to the DC bus of the rail vehicle, and the output ends of the M first energy feedback converters 1 are connected to M DC grid ports, which are used to convert the first DC voltage of the DC bus into the second DC voltage required by the DC grid, and feedback the second DC voltage to the DC grid corresponding to the DC grid port through the M DC grid ports, where M is a positive integer;

[0044] N second energy feedback converters 2, the input ends of the N second energy feedback converters 2 are connected to the DC bus of the rail vehicle, which are used to convert the first DC voltage of the DC bus into the first AC voltage;

[0045] N grid transformers 3, the input ends of the N grid transformers 3 are respectively connected to the output ends of the N second energy feedback converters 2 in a one-to-one correspondence, and the output ends of the N grid transformers 3 are respectively connected to N AC grid ports in a one-to-one correspondence, which are used to convert the first AC voltage into the second AC voltage required by the AC grid, and feedback the second AC voltage to the AC grid corresponding to the AC grid port through the N AC grid ports, where N is a positive integer.

[0046] Considering that when the traction motor of the rail vehicle is in the braking condition, the first DC voltage of the DC bus of the rail vehicle rises. When the first DC voltage exceeds the preset voltage threshold, the energy feedback system starts, and the energy is feedback to the grid through the regenerative braking energy feedback device. However, the existing regenerative braking energy feedback device can only feedback the energy of regenerative braking to the AC grid through the energy feedback converter and the energy feedback transformer, with a single feedback form and poor scalability.

[0047] To solve the above technical problems, the regenerative braking energy feedback device in this application includes M first energy feedback converters 1, N second energy feedback converters 2, and N grid transformers 3. Among them, the M first energy feedback converters 1 can perform DC-DC (Direct current-Direct current) conversion on the first DC voltage of the DC bus of the rail vehicle to obtain a second DC voltage, and feedback the second DC voltage to the DC grid corresponding to the DC grid port one by one through the M DC grid ports. M is a positive integer. The N second energy feedback converters 2 can perform DC-AC (Direct current-Alternating Current) conversion on the first DC voltage of the DC bus of the rail vehicle to obtain a first AC voltage, and then perform AC-AC (Alternating Current-Alternating Current) conversion on the first AC voltage through the N grid transformers 3 to obtain the second AC voltage required by the AC grid, and feedback the second AC voltage to the AC grid corresponding to the AC grid port one by one through the N AC grid ports. N is a positive integer. In this application, when the rail vehicle brakes, the first DC voltage of the DC bus of the rail vehicle is converted into the second DC voltage required by the DC grid through the M first energy feedback converters 1, and is converted into the second AC voltage required by the AC grid through the N second energy feedback converters 2 and the N grid transformers 3. Through the DC grid ports corresponding to the M first energy feedback converters 1 and the AC grid ports corresponding to the N grid transformers 3 one by one, it can not only realize the feedback of regenerative braking energy to AC grids of different voltage levels, but also feedback to DC grids of different voltage levels, such as 1180V AC grid, 400V AC grid, 900V DC grid or 1800V DC grid, forming an intelligent distribution network with rich ports, more flexible energy flow, promoting the integration of renewable energy, and making the access of green energy more convenient.

[0048] In addition, the regenerative braking energy feedback device also has the advantages of excellent performance, small volume, and high power density, higher intelligence level, and can meet various application environments. It can not only meet the transformation of existing urban rail power supply products, be suitable for the use of urban rail power supply products, but also meet the needs of new projects. It can also reserve an interface for the green intelligent energy system to effectively manage the access of green energy. That is, it can undertake the relevant power supply tasks of the station distribution system, and can also flexibly interact with the public grid in terms of energy. The energy can also be interacted between different power supply systems inside it.

[0049] Please refer to Figure 2 , Figure 2 which is the structural schematic diagram of another regenerative braking energy feedback device provided by this application.

[0050] For example, the DC grid port can be connected to the second energy feed converter 2 of the AC grid. As the energy source of the DC grid, on the one hand, when the traction motor of the rail vehicle is in the braking condition, the regenerative braking energy of the DC bus of the rail vehicle can be fed back to the DC grid through the first energy feed converter 1. On the other hand, when the traction motor of the rail vehicle is in the braking condition, the regenerative braking energy of the DC bus of the rail vehicle can also be first fed back to the AC grid, and then when the traction motor of the rail vehicle is in the traction condition, the AC grid energy can be transmitted to the DC grid.

[0051] In addition, when the traction of the rail vehicle causes the first DC voltage of the DC bus to decrease and be lower than the preset voltage threshold, the regenerative braking energy feedback device can also operate in the rectification state and work in coordination with the original traction system to keep the first DC voltage of the DC bus stable.

[0052] The grid transformer 3 can be, but is not limited to, a 12-pulse rectifier transformer to realize multiplexing with the traction branch transformer. Of course, a transformer independent of the traction branch can also be set.

[0053] The DC grid can be, but is not limited to, connected to new energy systems such as energy storage and photovoltaic.

[0054] The regenerative braking energy feedback device of the present application can select devices with high voltage levels and high switching frequencies. For example, devices with a voltage level of 3300V are selected, and the switching frequency of IGCT (Integrated Gate-Commutated Thyristor) is selected to be 5 - 6kHz to achieve high frequency, and also reduce the volume and weight of the device to realize miniaturization of the overall device. The present application does not make special limitations here.

[0055] In summary, the regenerative braking energy feedback device of the present application can not only feed back the regenerative braking energy to AC grids with different voltage levels, but also feed it back to DC grids with different voltage levels. The feedback form of the regenerative braking energy is more flexible and has stronger expandability.

[0056] Based on the above embodiments:

[0057] As a preferred embodiment, the first energy feed converter 1 includes:

[0058] The first H-bridge inverter module 11 with its input end as the input end of the first energy feed converter 1 is used to invert the first DC voltage of the DC bus to obtain a third AC voltage;

[0059] The first resonant module 12, the first resonant module 12 is connected in series with the primary winding of the first isolation transformer 13 and the series circuit is connected to the output end of the first H-bridge inverter module 11 for generating resonance;

[0060] The first isolation transformer 13 is used for electrically isolating the third AC voltage;

[0061] The first H-bridge rectification module 14, whose input terminal is connected to the secondary winding of the first isolation transformer 13 and whose output terminal serves as the output terminal of the first energy-feedback converter 1, is used for rectifying the third AC voltage to obtain a second DC voltage.

[0062] In order to reduce the losses of the devices in the energy feedback of the regenerative braking energy feedback device, in this embodiment, the first energy-feedback converter 1 includes a first H-bridge inversion module 11, a first resonance module 12, a first isolation transformer 13, and a first H-bridge rectification module 14. The first H-bridge inversion module 11 inverts the first DC voltage of the DC bus to obtain a third AC voltage. The first resonance module 12 generates resonance to achieve soft switching of the devices, which can greatly reduce the switching losses of the devices, ensure that the switching voltage of the devices will not be too high, thereby realizing high-frequency operation. In addition, it can also reduce the heat dissipation pressure of the overall device. The first isolation transformer 13 electrically isolates the third AC voltage, improving the reliability of the device. The first H-bridge rectification module 14 rectifies the third AC voltage to obtain a second DC voltage so as to feedback the second DC voltage to the DC grid. In summary, the first energy-feedback converter 1 of this embodiment has the advantages of soft switching, bidirectional energy flow, high efficiency, high power density, etc., improves the sinusoidality of the voltage, reduces the waveform distortion rate, reduces the losses of the devices in the energy feedback of the regenerative braking energy feedback device, and realizes high-frequency operation.

[0063] In addition, the first isolation transformer 13 can be but is not limited to a high-frequency isolation transformer. Since the primary topology of the transformer is a high-voltage system with a relatively high potential, the high-frequency isolation transformer can play the role of electrical isolation; in addition, in engineering applications, by selecting a high-frequency isolation transformer, the energy transmission efficiency can be improved, the volume and weight of the overall device can be reduced, the energy conversion loss can be reduced, the line loss can be reduced, the energy transmission distance can be farther, the exciting loss of the transformer can be reduced, and at the same time, the circulating current inside the device can also be suppressed.

[0064] Please refer to Figure 3 , Figure 3 which is a partial structural schematic diagram of a second energy-feedback converter provided by this application.

[0065] As a preferred embodiment, the second energy-feedback converter 2 includes:

[0066] The second H-bridge inversion module 21, whose input terminal serves as the input terminal of the second energy-feedback converter 2, is used for inverting the first DC voltage of the DC bus to obtain a fourth AC voltage;

[0067] The second resonance module 22, the second resonance module 22 is connected in series with the primary winding of the second isolation transformer 23, and the series circuit is connected to the output end of the second H-bridge inverter module 21, and is used to generate resonance;

[0068] The second isolation transformer 23 is used for electrical isolation of the fourth AC voltage;

[0069] The second capacitor;

[0070] The second H-bridge rectifier module 24 with its input end connected to the secondary winding of the second isolation transformer 23 and its output end connected to the input end of the four-quadrant module 25 through the second capacitor is used to rectify the fourth AC voltage to obtain the third DC voltage;

[0071] The four-quadrant module 25 with its output end serving as the output end of the second energy feedback converter 2 is used to invert the third DC voltage to obtain the first AC voltage.

[0072] In order to improve the efficiency of regenerative braking energy feedback, in this embodiment, the second energy feedback converter 2 includes a second H-bridge inverter module 21, a second resonance module 22, a second isolation transformer 23, a second capacitor, a second H-bridge rectifier module 24 and a four-quadrant module 25. Specifically, the second H-bridge inverter module 21 inverts the first DC voltage of the DC bus to obtain the fourth AC voltage. The second resonance module 22 can introduce resonance before and after the switching process of the devices in the regenerative braking energy feedback device, realize soft switching of the devices, ensure that the devices are turned on or off under zero voltage or zero current, so that the switching loss of the devices is reduced to the minimum, realize high frequency, and also reduce the heat dissipation pressure of the overall device. The second isolation transformer 23 performs electrical isolation on the fourth AC voltage, improving the reliability of the device. The second H-bridge rectifier module 24 rectifies the fourth AC voltage to obtain the third DC voltage. The four-quadrant module 25 can maintain the third DC voltage at a fixed voltage value, such as 1800V, and at the same time invert the third DC voltage to obtain the first AC voltage for feeding back the first AC voltage to the AC grid. In summary, the solution of this embodiment realizes independent control of active and reactive power, and the quality of the fed-back electric energy is excellent, improves the power density of the overall device and the efficiency of regenerative braking energy feedback, and realizes miniaturization of the overall device through high frequency.

[0073] In addition, the second isolation transformer 23 can be but is not limited to a high-frequency isolation transformer. Increasing the working frequency of the transformer can reduce its volume and weight without increasing the winding current density, can play an isolation role in suppressing circulating current, and reduces the floor space of the overall device.

[0074] The four - quadrant module 25 can also achieve bidirectional energy flow. It can not only meet the transmission requirements of braking energy, but also meet the transmission requirements of traction energy when the first DC voltage of the DC bus decreases. No special limitation is made in this application.

[0075] As a preferred embodiment, the second resonant module 22 includes a resonant inductor and a resonant capacitor, and the resonant inductor and the resonant capacitor are connected in series.

[0076] In order to improve the conversion efficiency of regenerative braking energy, in this embodiment, the second resonant module 22 selects an LC resonant module, which consists of a resonant inductor Lr and a resonant capacitor Cr. The resonant inductor Lr, the resonant capacitor Cr and the leakage inductance Lm of the primary side of the transformer form an LLC resonance. The overall circuit structure is simple, further reducing the switching losses of the devices, reducing the heat dissipation pressure of the overall device while achieving the purpose of high - frequency operation and high energy conversion efficiency. For example, the switching frequency of the devices can reach above 2 kHz.

[0077] Please refer to Figure 4 , Figure 4 which is a schematic structural diagram of a power supply system provided by this application.

[0078] As a preferred embodiment, the second energy - feedback converter 2 further includes a reactor 4. The input end of the reactor 4 is connected to the output end of the four - quadrant module 25, and the output end of the reactor 4 is connected to the grid transformer 3, which is used to filter the first AC voltage.

[0079] In order to improve the quality of regenerative braking energy feedback, in this embodiment, the second energy - feedback converter 2 can further include a reactor 4, which can filter the first AC voltage, prevent the high - order harmonics generated by the high voltage from polluting the AC power grid, and can control the harmonics through the reactor 4 to improve the quality of regenerative braking energy feedback.

[0080] As a preferred embodiment, it further includes a pre - charge module 5. The pre - charge module 5 is arranged between the grid transformer 3 and the second energy - feedback converter 2 and is used to pre - charge the second capacitor.

[0081] Considering that when the grid transformer 3 is switched on, the inrush current of the grid transformer 3 is too large, which may affect the second energy - feedback converter 2. In this embodiment, the regenerative braking energy feedback device further includes a pre - charge module 5, which can pre - charge the second capacitor of the second energy - feedback converter 2 to store energy. After the pre - charging of the second capacitor is completed, the inrush current subsides, thereby suppressing the influence of the inrush current on the second energy - feedback converter 2, and the circuit structure is simple, and the loss of the overall device is small.

[0082] As a preferred embodiment, the pre-charging module 5 includes a resistor, a first circuit breaker and a second circuit breaker;

[0083] The first circuit breaker is connected in series with the resistor and then in parallel with the second circuit breaker, and one end of the two ends after parallel connection is used as the input end of the pre-charging module 5, and the other end is used as the output end of the pre-charging module 5;

[0084] The first circuit breaker is used to conduct when the pre-charging of the second capacitor starts and disconnect after the pre-charging is completed;

[0085] The second circuit breaker is used to disconnect when the pre-charging of the second capacitor starts and conduct after the pre-charging is completed.

[0086] In this embodiment, the pre-charging module 5 can select a resistor, a first circuit breaker and a second circuit breaker. The first circuit breaker conducts when the pre-charging of the second capacitor starts and disconnects after the pre-charging is completed. The second circuit breaker disconnects when the pre-charging of the second capacitor starts and conducts after the pre-charging is completed. The overall circuit structure is simple, the operation is convenient, and the flexibility is strong. It realizes suppressing the influence of the magnetizing inrush current of the grid transformer 3 at the moment of closing on the second energy feedback converter 2, and improves the stability and reliability of the overall device.

[0087] As a preferred embodiment, it further includes:

[0088] M third energy feedback converters, and the M third energy feedback converters are connected in parallel with the M first energy feedback converters 1 one by one, and are used to convert the first DC voltage of the DC bus into the second DC voltage required by the DC grid, and feed back the second DC voltage to the DC grid corresponding to the DC grid port through the M DC grid ports, where M is a positive integer.

[0089] Considering the increase in the power and quantity of the rail vehicles operating in urban rail transit, it is required that the regenerative braking energy feedback device operates under high-power conditions. Obviously, the capacity of the first energy feedback converter 1 can no longer meet the requirements. In this embodiment, the regenerative braking energy feedback device may further include M third energy feedback converters. By adopting the method of connecting the M third energy feedback converters in parallel with the M first energy feedback converters 1 one by one, the first DC voltage of the DC bus can be converted into the second DC voltage required by the DC grid, and the second DC voltage can be fed back to the DC grid corresponding to the DC grid port through the M DC grid ports. This not only improves the power level of the overall device, but also the energy feedback converters are redundant with each other in parallel, improving the flexibility and reliability of the device.

[0090] As a preferred embodiment, it further includes:

[0091] N fourth energy feedback converters 6, and the N fourth energy feedback converters 6 are connected in parallel with the N second energy feedback converters 2 one by one, and are used to convert the first DC voltage of the DC bus into a first AC voltage.

[0092] In order to be able to feedback the regenerative braking energy generated by the rail vehicle to the AC power grid to the greatest extent, in this embodiment, the regenerative braking energy feedback device may further include N fourth energy feedback converters 6, which can convert the first DC voltage of the DC bus into a first AC voltage. By the way of being connected in parallel with the N second energy feedback converters 2 one by one, the power of the second energy feedback converters 2 can be expanded, and the regenerative braking energy can be feedback to the AC power grid with high power.

[0093] The present invention also provides a power supply system, including a traction transformer and a rectifier 7. The traction transformer is connected to the power supply grid of the rail vehicle, and the rectifier 7 is respectively connected to the traction transformer and the DC bus of the rail vehicle. The power supply system further includes the above-mentioned regenerative braking energy feedback device.

[0094] In addition, the grid transformer 3 and the traction transformer can be reused to realize the connection of the traction branch and the braking branch. When the first voltage of the DC bus of the rail vehicle decreases and is lower than the preset voltage threshold, the energy of the regenerative braking energy feedback device can not only be feedback to the AC power grid but also assist the traction branch to work, so as to keep the first DC voltage of the DC bus stable. This application does not make special limitations here.

[0095] The traction transformer can be, but is not limited to, a 12-pulse rectifier transformer, and the rectifier 7 can be, but is not limited to, a diode rectifier unit.

[0096] For more content about the working principle and working mode of the power supply system, reference can be made to the relevant descriptions of the above embodiments, which will not be elaborated here.

[0097] It should be noted that in this specification, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of another identical element in the process, method, article or device including the element.

[0098] The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A regenerative braking energy feedback device, characterized in that, Comprising: M first energy feedback converters, the input ends of the M first energy feedback converters are connected to the DC bus of the rail vehicle, and the output ends of the M first energy feedback converters are connected to M DC grid ports, for converting the first DC voltage of the DC bus into the second DC voltage required by the DC grid, and feeding back the second DC voltage to the corresponding DC grid through the M DC grid ports, where M is a positive integer; N second energy feedback converters, the input ends of the N second energy feedback converters are connected to the DC bus of the rail vehicle, for converting the first DC voltage of the DC bus into a first AC voltage; N grid transformers, the input ends of the N grid transformers are respectively connected to the output ends of the N second energy feedback converters in a one-to-one correspondence, and the output ends of the N grid transformers are respectively connected to N AC grid ports in a one-to-one correspondence, for converting the first AC voltage into the second AC voltage required by the AC grid, and feeding back the second AC voltage to the corresponding AC grid through the N AC grid ports, where N is a positive integer.

2. The regenerative braking energy feedback device according to claim 1, characterized in that The first energy feedback converter includes: A first H-bridge inverter module with its input end as the input end of the first energy feedback converter, for inverting the first DC voltage of the DC bus to obtain a third AC voltage; A first resonance module, the first resonance module is connected in series with the primary winding of the first isolation transformer and the series circuit is connected to the output end of the first H-bridge inverter module, for generating resonance; The first isolation transformer, for electrically isolating the third AC voltage; A first H-bridge rectifier module with its input end connected to the secondary winding of the first isolation transformer and its output end as the output end of the first energy feedback converter, for rectifying the third AC voltage to obtain the second DC voltage.

3. The regenerative braking energy feedback device according to claim 1, characterized in that, The second energy feedback converter includes: A second H-bridge inverter module with its input end as the input end of the second energy feedback converter, for inverting the first DC voltage of the DC bus to obtain a fourth AC voltage; A second resonance module, the second resonance module is connected in series with the primary winding of the second isolation transformer and the series circuit is connected to the output end of the second H-bridge inverter module, for generating resonance; The second isolation transformer, for electrically isolating the fourth AC voltage; A second capacitor; A second H-bridge rectifier module with its input end connected to the secondary winding of the second isolation transformer and its output end connected to the input end of the four-quadrant module through the second capacitor, for rectifying the fourth AC voltage to obtain a third DC voltage; The four-quadrant module with its output end as the output end of the second energy feedback converter, for inverting the third DC voltage to obtain the first AC voltage.

4. The regenerative braking energy feedback device according to claim 3, characterized in that, The second resonance module includes a resonance inductor and a resonance capacitor, and the resonance inductor and the resonance capacitor are connected in series.

5. The regenerative braking energy feedback device according to claim 3, characterized in that The second energy feedback converter further includes a reactor. The input end of the reactor is connected to the output end of the four-quadrant module, and the output end of the reactor is connected to the grid transformer, and is used for filtering the first AC voltage.

6. The regenerative braking energy feedback device according to claim 3, wherein, It further includes a pre-charging module. The pre-charging module is arranged between the grid transformer and the second energy feedback converter, and is used for pre-charging the second capacitor.

7. The regenerative braking energy feedback device according to claim 6, wherein The pre-charging module includes a resistor, a first circuit breaker and a second circuit breaker; The first circuit breaker is connected in series with the resistor and then connected in parallel with the second circuit breaker, and one end of the two ends after parallel connection is used as the input end of the pre-charging module, and the other end is used as the output end of the pre-charging module; The first circuit breaker is used to conduct when the pre-charging of the second capacitor starts and disconnect after the pre-charging is completed; The second circuit breaker is used to disconnect when the pre-charging of the second capacitor starts and conduct after the pre-charging is completed.

8. The regenerative braking energy feedback device according to any one of claims 1 to 7, characterized in that It further includes: M third energy feedback converters. The M third energy feedback converters are connected in parallel with the M first energy feedback converters one by one, and are used for converting the first DC voltage of the DC bus into the second DC voltage required by the DC grid, and feeding back the second DC voltage to the DC grid corresponding to the DC grid port through the M DC grid ports, where M is a positive integer.

9. The regenerative braking energy feedback device according to any one of claims 1 to 7, characterized in that It further includes: N fourth energy feedback converters. The N fourth energy feedback converters are connected in parallel with the N second energy feedback converters one by one, and are used for converting the first DC voltage of the DC bus into the first AC voltage.

10. A power supply system, characterized in that, It includes a traction transformer and a rectifier. The traction transformer is connected to the power supply grid of the rail vehicle, and the rectifier is respectively connected to the traction transformer and the DC bus of the rail vehicle. The power supply system further includes the regenerative braking energy feedback device according to any one of claims 1 to 9.

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