Traction converter and EMU traction drive system

Abstract

The present invention provides a traction converter and a traction drive system for a multiple unit train. The traction converter of the present invention comprises: 4QC, a bidirectional DC / DC converter, and a traction inverter; wherein, the 4QC is used to electrically connect to the overhead line, the 4QC is electrically connected to the bidirectional DC / DC converter, the bidirectional DC / DC converter is electrically connected to the traction inverter, and the traction inverter is used to electrically connect to the traction motor; the bidirectional DC / DC converter is used to set the power of the bidirectional DC / DC converter to be equal to the secondary pulsating power on the DC side of the 4QC, so as to suppress the secondary pulsating voltage on the DC side of the 4QC. The present invention achieves the suppression of the secondary pulsating voltage on the DC side of the 4QC by setting the power of the bidirectional DC / DC converter to be equal to the secondary pulsating power on the DC side of the 4QC, so that the traction converter can adapt to various working conditions in the actual operation of the locomotive, and also reduces the volume and weight of the traction converter, thereby improving the power density of the traction converter.

Description

Technical Field

[0001] The present invention relates to the technical field of rail transit, and in particular to a traction converter and a traction drive system for an EMU. Background Art

[0002] With the innovation and development of key technologies for high-speed railways, how to reduce the weight of the locomotive, lower the manufacturing cost of the locomotive, and simplify the manufacturing process of the locomotive have also become key issues in achieving locomotive optimization, especially the optimization of the traction inverter, which is one of the important components of the locomotive.

[0003] Due to the single-phase power supply characteristics of high-speed railways, there is always a secondary pulsating power in the grid-side input instantaneous power of the traction inverter, which will cause the DC voltage output by the four-quadrant rectifier 4QC at the front end of the traction inverter to have a voltage pulsation with a frequency of twice the industrial frequency. This secondary pulsating voltage will have an extremely adverse effect on the entire traction drive system.

[0004] The traditional method of suppressing secondary pulsating voltage mainly adopts LC secondary filter, 4QC is connected to LC secondary filter, and LC secondary filter is connected to traction inverter. Specifically, the series-connected inductor L and capacitor C are connected in parallel at both ends of the DC side of 4QC, and at the same time in parallel at both ends of the DC side of traction inverter. However, due to the large size, high weight and complex manufacturing process of LC secondary filter itself, the traction converter is large in size, high in weight and high in production cost. Therefore, there is an urgent need for a traction converter with small size, low cost and the ability to suppress secondary pulsating voltage. Summary of the invention

[0005] The present invention provides a traction converter and a traction drive system for a motor vehicle group, so as to solve the problems of large volume, high weight and high production cost of the traction converter in the prior art.

[0006] In a first aspect, the present invention provides a traction converter, comprising: a four-quadrant rectifier 4QC, a bidirectional DC / DC converter, and a traction inverter;

[0007] Wherein, the 4QC is used to electrically connect to the overhead line, the 4QC is electrically connected to the bidirectional DC / DC converter, the bidirectional DC / DC converter is electrically connected to the traction inverter, and the traction inverter is used to electrically connect to the traction motor;

[0008] The bidirectional DC / DC converter is used to set the power of the bidirectional DC / DC converter to be equal to the secondary pulsating power of the 4QC DC side, so as to suppress the secondary pulsating voltage of the 4QC DC side.

[0009] Optionally, the traction converter further comprises: a processor; the bidirectional DC / DC converter comprises: a first switching element, a second switching element, and a filtering energy storage unit;

[0010] Wherein, the first end of the first switch element is electrically connected to the first output end of the 4QC DC side, the second end of the first switch element is electrically connected to the first end of the second switch element, the second end of the second switch element is electrically connected to the second output end of the 4QC DC side, the first end of the filter energy storage unit is electrically connected to both the second end of the first switch element and the first end of the second switch element, the second end of the filter energy storage unit is electrically connected to the second output end of the 4QC DC side, and the power of the filter energy storage unit is equal to the secondary pulsating power of the 4QC DC side;

[0011] The control end of the first switch element and the control end of the second switch element are electrically connected to the processor respectively; the processor is used to control the conduction and disconnection of the first switch element and the second switch element.

[0012] Optionally, the first switching element and the second switching element are insulated gate bipolar transistor (IGBT) modules.

[0013] Optionally, the filtering energy storage unit comprises: a filtering inductor and an energy pack;

[0014] The first end of the filter inductor is electrically connected to the second end of the first switch element and the first end of the second switch element, the first end of the energy packet is electrically connected to the second output end of the 4QC DC side, and the power of the energy packet is equal to the secondary pulsating power of the 4QC DC side;

[0015] The control end of the energy packet is electrically connected to the processor; the processor is used to control whether the second end of the energy packet is connected to or disconnected from the second end of the filter inductor.

[0016] Optionally, the energy pack includes: a first contactor and a filter capacitor;

[0017] The second end of the filter inductor is electrically connected to the first end of the first contactor, the second end of the first contactor is electrically connected to the first end of the filter capacitor, the second end of the filter capacitor is electrically connected to the second output end of the 4QC DC side, and the power of the filter capacitor is equal to the secondary pulsating power of the 4QC DC side;

[0018] The control end of the first contactor is electrically connected to the processor; the processor is used to control the on or off of the first contactor to connect or disconnect the filter capacitor and the filter inductor.

[0019] Optionally, the filter capacitor is a super capacitor.

[0020] Optionally, the energy pack further comprises: a second contactor and a first power battery pack;

[0021] The second end of the filter inductor is electrically connected to the first end of the second contactor, the second end of the second contactor is electrically connected to the first end of the first power battery pack, and the second end of the first power battery pack is electrically connected to the second output end of the 4QC DC side;

[0022] The control end of the first power battery pack is electrically connected to the processor; the processor is used to control the second contactor to be turned on or off so as to connect or disconnect the first power battery pack and the filter inductor.

[0023] Optionally, the energy pack includes: a second power battery pack;

[0024] The second end of the filter inductor is electrically connected to the first end of the second power battery pack, the second end of the second power battery pack is electrically connected to the second output end of the 4QC DC side, and the power of the second power battery pack is equal to the secondary pulsating power of the 4QC DC side;

[0025] The control end of the second power battery pack is electrically connected to the processor; and the processor is used to control whether the second power battery pack is connected to or disconnected from the filter inductor.

[0026] Optionally, the traction converter further comprises: an auxiliary inverter;

[0027] Wherein, the auxiliary inverter is electrically connected to the bidirectional DC / DC converter, and the auxiliary inverter is used to be electrically connected to the vehicle.

[0028] In a second aspect, the present invention provides a traction drive system for an EMU, comprising: a contact network, a traction motor, and a traction converter as described in the first aspect;

[0029] The contact network is electrically connected to the traction inverter, and the traction inverter is electrically connected to the traction motor.

[0030] The traction converter and EMU traction drive system provided by the present invention, the traction converter includes a four-quadrant rectifier 4QC, a bidirectional DC / DC converter and a traction inverter. By connecting 4QC to the contact network, the AC voltage on the contact network can be obtained, and 4QC converts the AC voltage into a DC voltage. When the traction converter needs filtering, by connecting 4QC to the bidirectional DC / DC converter, and setting the power of the bidirectional DC / DC converter equal to the secondary pulsating power on the DC side of 4QC, the bidirectional DC / DC converter can suppress the secondary pulsating voltage on the DC side of 4QC to achieve filtering. By connecting the bidirectional DC / DC converter to the traction inverter, the traction inverter can obtain a DC voltage with good performance, and the traction inverter can reliably and stably supply power to the traction motor. In the present invention, by setting the power of the bidirectional DC / DC converter equal to the secondary pulsating power on the 4QC DC side, the secondary pulsating voltage on the 4QC DC side is suppressed, so that the traction inverter can adapt to various working conditions in the actual operation of the locomotive, and the volume and weight of the traction inverter are reduced, thereby improving the power density of the traction inverter. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0032] Figure 1 A schematic diagram of the structure of the traction converter provided by the present invention;

[0033] Figure 2 A schematic diagram of the structure of the traction converter provided by the present invention;

[0034] Figure 3 A schematic diagram of the structure of an energy package in a traction converter provided by the present invention;

[0035] Figure 4 A schematic diagram of the structure of an energy package in a traction converter provided by the present invention;

[0036] Figure 5 A schematic diagram of the structure of an energy package in a traction converter provided by the present invention;

[0037] Figure 6 A schematic diagram of the structure of the traction converter provided by the present invention;

[0038] Figure 7 This is a schematic structural diagram of the EMU traction drive system provided by the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments in the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the embodiments of the present invention.

[0040] Figure 1 A schematic diagram of the structure of the traction converter provided by the present invention is shown in FIG. Figure 1 As shown, the traction converter 10 of this embodiment may include: 4QC 11, a bidirectional DC / DC converter 12, and a traction inverter 13;

[0041] Among them, 4QC11 is used to electrically connect to the overhead line, 4QC11 is electrically connected to the bidirectional DC / DC converter 12, the bidirectional DC / DC converter 12 is electrically connected to the traction inverter 13, and the traction inverter 13 is used to electrically connect to the traction motor;

[0042] The bidirectional DC / DC converter 12 is used to set the power of the bidirectional DC / DC converter 12 to be equal to the secondary pulsating power on the DC side of the 4QC11, so as to suppress the secondary pulsating voltage on the DC side of the 4QC11.

[0043] Specifically, in this embodiment, 4QC11 can convert the AC voltage on the contact network into a DC voltage through the connection of the contact network. The bidirectional DC / DC converter 12 can suppress the secondary pulsating voltage on the DC side of 4QC11 by connecting with 4QC11 and setting the power of the bidirectional DC / DC converter 12 to the secondary pulsating power on the DC side of 4QC11, so that the bidirectional DC / DC converter 12 can obtain a good DC voltage by being electrically connected to the traction inverter 13, and then provide a reliable voltage to the traction motor, so that the locomotive can adapt to various working conditions of actual movement. Among them, this embodiment does not limit the specific form of the bidirectional DC / DC converter 12.

[0044] Furthermore, the traditional method of using LC secondary filter to suppress secondary pulsating voltage has the problems of large volume, high weight and complex manufacturing process, resulting in large volume and high cost of traction converter 10. In this embodiment, by setting the power of bidirectional DC / DC converter 12 equal to the secondary pulsating power on the DC side of 4QC11, it can suppress the voltage pulse on the DC side of 4QC11, effectively improve the power density of traction converter 10, greatly reduce the volume and weight of traction converter 10, and save costs, overcome the disadvantage that LC secondary filtering can only compensate for fixed frequency harmonics, can adapt to complex power grid environment, and has a more ideal suppression effect than traditional methods.

[0045] The traction converter provided in this embodiment includes a four-quadrant rectifier 4QC, a bidirectional DC / DC converter and a traction inverter. By connecting 4QC to the contact network, the AC voltage on the contact network can be obtained, and 4QC converts the AC voltage into a DC voltage. When the traction converter needs filtering, by connecting 4QC to the bidirectional DC / DC converter and setting the power of the bidirectional DC / DC converter equal to the secondary pulsating power on the DC side of 4QC, the bidirectional DC / DC converter can suppress the secondary pulsating voltage on the DC side of 4QC to achieve filtering. By connecting the bidirectional DC / DC converter to the traction inverter, the traction inverter can obtain a DC voltage with good performance, and the traction inverter can reliably and stably supply power to the traction motor. In the present invention, by setting the power of the bidirectional DC / DC converter equal to the secondary pulsating power on the DC side of 4QC, the secondary pulsating voltage on the DC side of 4QC is suppressed, so that the traction converter can adapt to various working conditions in the actual operation of the locomotive, and the volume and weight of the traction converter are reduced, thereby improving the power density of the traction converter.

[0046] Below, in the above Figure 1 Based on the embodiment, the traction converter 10 further includes: a processor ( Figure 1 not shown), combined Figure 2 , the specific structure of the bidirectional DC / DC converter 12 in the embodiment is described in detail. Figure 2 A schematic diagram of the structure of the traction converter provided by the present invention is shown in FIG. Figure 2 As shown, the bidirectional DC / DC converter 12 of this embodiment includes: a first switch element 121, a second switch element 122, and a filtering energy storage unit 123;

[0047] Wherein, the first end of the first switching element 121 is electrically connected to the first output end of the DC side of 4QC11, the second end of the first switching element 121 is electrically connected to the first end of the second switching element 122, the second end of the second switching element 122 is electrically connected to the second output end of the DC side of 4QC11, the first end of the filtering energy storage unit 123 is electrically connected to both the second end of the first switching element 121 and the first end of the second switching element 122, the second end of the filtering energy storage unit 123 is electrically connected to the second output end of the DC side of 4QC11, and the power of the filtering energy storage unit 123 is equal to the secondary pulsating power of the DC side of 4QC11;

[0048] The control end of the first switch element 121 and the control end of the second switch element 122 are electrically connected to the processor respectively; the processor is used to control the conduction and disconnection of the first switch element 121 and the second switch element 122.

[0049] Specifically, in this embodiment, the processor can control the on and off of the first switch element 121 and the second switch element 122 by connecting to the control end of the first switch element 121 and the control end of the second switch element 122 respectively, so as to control the charging and discharging direction of the filter energy storage unit 123. When the first switch element 121 is turned on and the second switch element 122 is turned off, the filter energy storage unit 123 is charged; when the first switch element 121 is turned off and the second switch element 122 is turned on, the filter energy storage unit 123 is discharged.

[0050] Among them, this embodiment does not limit the specific form of the first switch element 121 and the second switch element 122. Optionally, the first switch element 121 and the second switch element 122 are insulated gate bipolar transistor (IGBT) modules. Specifically, since 4QC11 also includes multiple IGBT modules, in order to facilitate the hardware design of the entire traction converter 10, this embodiment can make the withstand voltage level of the first switch element 121 and the second switch element 122 the same as the IGBT module in 4QC11, which is easy to integrate with the previous stage 4QC11, saving cost and space, and reducing the volume of the entire traction converter 10.

[0051] Furthermore, in this embodiment, by setting the power of the filter energy storage unit 123 to be equal to the secondary pulsating power on the DC side of 4QC11, the secondary pulse voltage on the DC side of 4QC11 can be suppressed, thereby playing a filtering role. It is easy for those skilled in the art to understand that once there is a slight deviation in the contact network frequency, the suppression effect of the LC secondary filter in the prior art will deteriorate, resulting in low working efficiency of the traction converter 10, unstable working process, or even damage resulting in failure to work normally. In this embodiment, since the filter energy storage unit 123 is not directly connected to the DC side of 4QC11, whether the filter energy storage unit 123 increases or decreases the voltage or current, the power density of the traction converter 10 can be improved.

[0052] Furthermore, in addition to filtering, the filter energy storage unit 123 can also be used as a drive device for energy storage elements, for different levels of voltage conversion and energy flow control, to stabilize the intermediate DC link voltage. The specific structure of the filter energy storage unit 123 is not limited in this embodiment.

[0053] Continue to combine Figure 2 , Optionally, the filtering energy storage unit 123 includes: a filtering inductor 1231 and an energy pack 1232;

[0054] The first end of the filter inductor 1231 is electrically connected to the second end of the first switch element 121 and the first end of the second switch element 122, the first end of the energy packet 1232 is electrically connected to the second output end of the DC side of the 4QC11, and the power of the energy packet 1232 is equal to the secondary pulsating power of the DC side of the 4QC11;

[0055] The control end of the energy packet 1232 is electrically connected to the processor; the processor is used to control whether the second end of the energy packet 1232 is connected or disconnected from the second end of the filter inductor 1231.

[0056] Specifically, in this embodiment, the first end of the filter inductor 1231 is connected to the midpoint of the first switch element 121 and the second switch element 122, and the first end of the energy packet 1232 is electrically connected to the second output end of the DC side of 4QC11. When the traction converter 10 needs to be filtered, the processor can control the second end of the energy packet 1232 to be connected to the second end of the filter inductor 1231. Since the power of the energy packet 1232 is set equal to the secondary pulsating power on the DC side of 4QC11, the filter inductor 1231 and the energy packet 1232 can play a filtering role, compensate for the secondary pulsating voltage on the DC side of 4QC11, and the energy packet 1232 can also be used as an energy storage element to realize charging and / or discharging of the traction converter 10. When the traction inverter 10 does not need to perform filtering, the processor can control the second end of the energy packet 1232 to be disconnected from the second end of the filter inductor 1231. Since the filter inductor 1231 and the energy packet 1232 are not directly connected to 4QC11, even if the current of the filter inductor 1231 and the voltage of the energy packet 1232 change, it will not have an adverse effect on the normal operation of the traction inverter 10.

[0057] The present embodiment does not limit the specific implementation of the energy packet 1232. Figure 3-5 , the specific form of the energy package 1232 is described in detail in three ways.

[0058] The first possible implementation method is Figure 3 The schematic diagram of the structure of the energy package in the traction converter provided by the present invention is as follows: Figure 3 As shown, optionally, the energy package 1232 in this embodiment includes: a first contactor 12321 and a filter capacitor 12322;

[0059] The second end of the filter inductor 1231 is electrically connected to the first end of the first contactor 12321, the second end of the first contactor 12321 is electrically connected to the first end of the filter capacitor 12322, the second end of the filter capacitor 12322 is electrically connected to the second output end of the DC side of 4QC11, and the power of the filter capacitor 12322 is equal to the secondary pulsating power of the DC side of 4QC11;

[0060] The control end of the first contactor 12321 is electrically connected to the processor; the processor is used to control the on or off of the first contactor 12321 to connect or disconnect the filter capacitor 12322 and the filter inductor 1231.

[0061] Specifically, in this embodiment, the first contactor 12321 can be controlled by the processor to be turned on or off according to whether the traction converter 10 needs filtering, so that the filter capacitor 12322 is connected or disconnected from the filter inductor 1231. When the traction converter 10 needs to be filtered, the processor turns on the first contactor 12321, so that the filter capacitor 12322 is connected to the filter inductor 1231, thereby completing the filtering process of the secondary pulsating voltage on the DC side of 4QC11. When the traction converter 10 does not need to be filtered, the processor turns off the first contactor 12321, so that the filter capacitor 12322 is disconnected from the filter inductor 1231, so that the traction converter 10 completes other normal working processes. Among them, this embodiment does not limit the specific forms of the first contactor 12321 and the filter capacitor 12322. Optionally, the filter capacitor 12322 is a super capacitor. Supercapacitors are between traditional capacitors and batteries. They are a power source with special properties. They have the characteristics of high power density, short charging and discharging time, and long cycle life. Therefore, supercapacitors can not only achieve filtering together with filter inductor 1231, but also be used as an energy source for charging and discharging.

[0062] A second feasible implementation method is as follows: Figure 3 Based on the examples, Figure 4 The schematic diagram of the structure of the energy package in the traction converter provided by the present invention is as follows: Figure 4 As shown, when the filter capacitor 12322 adopts a common capacitor, the energy pack 1232 in this embodiment further includes: a second contactor 12323 and a first power battery pack 12324;

[0063] The second end of the filter inductor 1231 is electrically connected to the first end of the second contactor 12323, the second end of the second contactor 12323 is electrically connected to the first end of the first power battery pack 12324, and the second end of the first power battery pack 12324 is electrically connected to the second output end of the DC side of 4QC11;

[0064] The control end of the first power battery pack 12324 is electrically connected to the processor; the processor is used to control the second contactor 12323 to be turned on or off, so as to connect or disconnect the first power battery pack 12324 and the filter inductor 1231.

[0065] Specifically, when the filter capacitor 12322 adopts an ordinary capacitor, the second end of the filter inductor 1231 is not only connected to the first end of the first contactor 12321, so that the filter inductor 1231 and the filter capacitor 12322 can achieve the filtering effect on the secondary pulsating voltage of 4QC11, but also connected to the first end of the second contactor 12323, so that the first power battery pack 12324 can be used as an energy storage element to achieve the function of charging and discharging. When the traction converter 10 needs the first power battery pack 12324 to release energy or store energy to the first power battery pack 12324, the processor can control the second contactor 12323 to be turned on, so that the first power battery pack 12324 can achieve the process of charging and discharging; when the traction converter 10 does not need the first power battery pack 12324 to release energy or does not need to store energy to the first power battery pack 12324, the processor can control the second contactor 12323 to be turned off, so that the first power battery pack 12324 stops the process of charging and discharging.

[0066] The third possible implementation method is: Figure 5 The schematic diagram of the structure of the energy package in the traction converter provided by the present invention is as follows: Figure 5 As shown, optionally, the energy pack 1232 in this embodiment includes: a second power battery pack 12325;

[0067] The second end of the filter inductor 1231 is electrically connected to the first end of the second power battery pack 12325, the second end of the second power battery pack 12325 is electrically connected to the second output end of the DC side of 4QC11, and the power of the second power battery pack 12325 is equal to the secondary pulsating power of the DC side of 4QC11;

[0068] The control end of the second power battery pack 12325 is electrically connected to the processor; the processor is used to control whether the second power battery pack 12325 is connected or disconnected from the filter inductor 1231.

[0069] Specifically, on the one hand, this embodiment can control the connection or disconnection between the second power battery pack 12325 and the filter inductor 1231 through the processor according to whether the traction converter 10 needs to filter. When the traction converter 10 needs to filter, the processor controls the connection between the second power battery pack 12325 and the filter inductor 1231 to achieve the filtering process of the secondary pulsating voltage on the DC side of 4QC11. When the traction converter 10 does not need to filter, the processor controls the second power battery pack 12325 to disconnect from the filter inductor 1231, so that the traction converter 10 completes other normal working processes. Among them, this embodiment does not limit the specific form of the second power battery pack 12325.

[0070] On the other hand, since the second power battery pack 12325 in this embodiment has the advantages of high energy density and large charge and discharge rate, and the second power battery pack 12325 can be provided with a separate battery management system, which is beneficial to the energy management of the traction inverter 10, therefore, in this embodiment, the second power battery pack 12325 can be used as an energy storage element to realize the charging and discharging of the traction inverter 10.

[0071] Then, in Figure 1 Based on Figure 6 , the specific structure of the traction converter of this embodiment is described in detail. Figure 6 A schematic diagram of the structure of the traction converter provided by the present invention is shown in FIG. Figure 6 As shown, the traction converter 10 of this embodiment further includes: an auxiliary inverter 14;

[0072] The auxiliary inverter 14 is electrically connected to the bidirectional DC / DC converter 12 , and the auxiliary inverter 14 is used for electrically connecting to the vehicle.

[0073] Specifically, since the locomotive requires voltages of various magnitudes, an auxiliary inverter 14 may be provided in this embodiment to obtain a DC voltage through the connection of the bidirectional DC / DC converter 12 and provide a reliable and stable power supply voltage to the locomotive. This embodiment does not limit the specific implementation of the auxiliary inverter 14.

[0074] In order to facilitate understanding of the role of the bidirectional DC / DC converter 12 in the traction converter 10, the following describes in detail the filtering and energy storage roles of the bidirectional DC / DC converter 12 when the train is in different vehicle conditions. Figure 4 The specific structure shown.

[0075] When the contact network is the main energy source of 4QC11, the train is in traction condition, the train accelerates, the load power increases and maintains constant power, the contact network and 4QC11 are the main energy sources, and the bidirectional DC / DC converter 12 switches to the filtering mode. The processor controls the first contactor 12321 to be turned on, and the filter inductor 1231 is connected to the filter capacitor 12322, so that the bidirectional DC / DC converter 12 plays a filtering role.

[0076] When the contact network does not provide an energy source for 4QC11, the train is in a braking condition, and the first power battery group 12324 in the energy pack 1232 is charged for the next discharge, and the train braking energy will not be fed back to the contact network.

[0077] When the overhead line does not provide an energy source for 4QC11, the core function of the bidirectional DC / DC converter 12 is to maintain a constant voltage in the intermediate DC link, which can ensure the normal operation of the traction inverter 13 and the auxiliary inverter 14. When the train is in traction (or emergency start) or coasting mode, the traction converter 10 does not need filtering, and the first contactor 12321 can be controlled to be turned off, disconnecting the connection between the filter inductor 1231 and the filter capacitor 12322, and the first power battery pack 12324 will release energy to maintain the stability of the intermediate DC link voltage of the traction converter 10.

[0078] When the overhead line does not provide energy source for 4QC11, the train is in braking condition, the train is in deceleration condition, the traction inverter 13 converts the kinetic energy of the train into electrical energy and feeds it back to the intermediate DC link, and the first power battery pack 12324 absorbs this part of the braking energy. And the traction inverter 13 is changed from a load to a power source, and since its power is not stable, the first power battery pack 12324 stabilizes the intermediate DC link voltage of the traction converter 10 by absorbing or releasing energy.

[0079] When the train enters the phase separation area, 4QC11 cannot work in the phase separation area due to the lack of electricity in the contact network. Since the power EMU is equipped with an energy storage device, namely the first power battery pack 12324, the first power battery pack 12324 can be used to stabilize the intermediate DC link in the phase separation area to ensure the normal operation of the train.

[0080] Figure 7 The structural diagram of the traction drive system of the EMU provided by the present invention is as follows: Figure 7 As shown, the EMU traction drive system 70 of this embodiment includes: a contact network 71, a traction motor 72 and a traction converter 73 as described above;

[0081] The overhead contact network 71 is electrically connected to the traction converter 73 , and the traction converter 73 is electrically connected to the traction motor 72 .

[0082] The EMU traction drive system provided in the embodiment of the present invention includes the traction inverter as described above, and can execute the above embodiment. Its specific implementation principles and technical effects can be found in the above method embodiment, and this embodiment will not be repeated here.

[0083] Those skilled in the art can understand that all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, disk or optical disk and other media that can store program codes.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention 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 replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A traction converter, characterized in that: include: Four-quadrant rectifier 4QC, bidirectional DC / DC converter, traction inverter; Wherein, the 4QC is used to electrically connect to the overhead line, the 4QC is electrically connected to the bidirectional DC / DC converter, the bidirectional DC / DC converter is electrically connected to the traction inverter, and the traction inverter is used to electrically connect to the traction motor; The bidirectional DC / DC converter is used to set the power of the bidirectional DC / DC converter to be equal to the secondary pulsating power of the 4QC DC side, so as to suppress the secondary pulsating voltage of the 4QC DC side; The traction converter further comprises: a processor; the bidirectional DC / DC converter comprises: a first switch element, a second switch element, and a filtering energy storage unit; Wherein, the first end of the first switch element is electrically connected to the first output end of the 4QC DC side, the second end of the first switch element is electrically connected to the first end of the second switch element, the second end of the second switch element is electrically connected to the second output end of the 4QC DC side, the first end of the filter energy storage unit is electrically connected to both the second end of the first switch element and the first end of the second switch element, the second end of the filter energy storage unit is electrically connected to the second output end of the 4QC DC side, and the power of the filter energy storage unit is equal to the secondary pulsating power of the 4QC DC side; The control end of the first switch element and the control end of the second switch element are electrically connected to the processor respectively; the processor is used to control the conduction and disconnection of the first switch element and the second switch element; The first switching element and the second switching element are insulated gate bipolar transistor IGBT modules; The filtering energy storage unit comprises: a filtering inductor and an energy pack; The first end of the filter inductor is electrically connected to the second end of the first switch element and the first end of the second switch element, the first end of the energy packet is electrically connected to the second output end of the 4QC DC side, and the power of the energy packet is equal to the secondary pulsating power of the 4QC DC side; The control end of the energy packet is electrically connected to the processor; the processor is used to control whether the second end of the energy packet is connected to or disconnected from the second end of the filter inductor.

2. The traction converter according to claim 1, characterized in that: The energy pack includes: a first contactor and a filter capacitor; The second end of the filter inductor is electrically connected to the first end of the first contactor, the second end of the first contactor is electrically connected to the first end of the filter capacitor, the second end of the filter capacitor is electrically connected to the second output end of the 4QC DC side, and the power of the filter capacitor is equal to the secondary pulsating power of the 4QC DC side; The control end of the first contactor is electrically connected to the processor; the processor is used to control the on or off of the first contactor to connect or disconnect the filter capacitor and the filter inductor.

3. The traction converter according to claim 2, characterized in that: The filter capacitor is a super capacitor.

4. The traction converter according to claim 2, characterized in that: The energy pack further comprises: a second contactor and a first power battery pack; The second end of the filter inductor is electrically connected to the first end of the second contactor, the second end of the second contactor is electrically connected to the first end of the first power battery pack, and the second end of the first power battery pack is electrically connected to the second output end of the 4QC DC side; The control end of the first power battery pack is electrically connected to the processor; the processor is used to control the second contactor to be turned on or off so as to connect or disconnect the first power battery pack and the filter inductor.

5. The traction converter according to claim 1, characterized in that: The energy pack includes: a second power battery pack; The second end of the filter inductor is electrically connected to the first end of the second power battery pack, the second end of the second power battery pack is electrically connected to the second output end of the 4QC DC side, and the power of the second power battery pack is equal to the secondary pulsating power of the 4QC DC side; The control end of the second power battery pack is electrically connected to the processor; and the processor is used to control whether the second power battery pack is connected to or disconnected from the filter inductor.

6. The traction converter according to claim 1, characterized in that: The traction converter further includes: an auxiliary inverter; Wherein, the auxiliary inverter is electrically connected to the bidirectional DC / DC converter, and the auxiliary inverter is used to be electrically connected to the vehicle.

7. A traction drive system for an EMU, characterized in that: include: A contact network, a traction motor and a traction converter according to any one of claims 1 to 6; The contact network is electrically connected to the traction inverter, and the traction inverter is electrically connected to the traction motor.

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