A traction converter

Abstract

This invention discloses a traction converter, relating to the field of traction converters. When powered by a power battery, a first power battery sequentially powers a first traction motor through a first switching module and a first inverter module, and powers an auxiliary load through a first auxiliary transformer module and a first transformer. Similarly, a second power battery sequentially powers a second traction motor through a second switching module and a second inverter module, and powers an auxiliary load through a second auxiliary transformer module and a second transformer. When charging the power batteries, power is supplied to the first power battery through a charging port, a first transformer, and a first auxiliary transformer module; and the second power battery is charged through a charging port, a second transformer, and a second auxiliary transformer module. During normal charging and power supply, the first and second auxiliary transformer modules, as well as the first and second transformers, are reused, eliminating the need for additional charging circuits for the first and second power batteries, thereby reducing the size and cost of the traction converter.

Description

Technical Field

[0001] This invention relates to the field of traction converters, and in particular to a traction converter. Background Technology

[0002] With the promotion and use of clean energy, traction systems powered by new energy sources are gradually becoming one of the new directions for development in the rail transit field. New energy sources, such as power batteries, supply power to the traction converter. Specifically, the onboard traction converter converts the DC power provided by the power battery into AC power to supply power to the traction motor and auxiliary loads.

[0003] When the power battery is low on power, it needs to be charged. In the existing technology, an additional charging circuit is usually set up in the traction converter to charge the power battery. However, the traction converter is relatively expensive and heavy. Summary of the Invention

[0004] The purpose of this invention is to provide a traction converter that, when the power battery is charging and supplying power normally, enables the reuse of the first auxiliary transformer module and the second auxiliary transformer module, as well as the first transformer and the second transformer, eliminating the need for additional charging circuits for the first and second power batteries, thereby reducing the size and cost of the traction converter.

[0005] To solve the above-mentioned technical problems, the present invention provides a traction converter, comprising:

[0006] The first switch module has a first end connected to the first power battery and a second end connected to the DC end of the first inverter module and the DC end of the first auxiliary transformer module, respectively.

[0007] The first inverter module has its AC terminal connected to the first traction motor and is used to convert the first power supply DC power into the first power supply AC power to power the first traction motor.

[0008] The first auxiliary transformer module has its AC terminal connected to the input terminal of the first transformer and is used to convert the first power supply DC current into the second power supply AC current and the first charging AC current into the first charging DC current.

[0009] The first transformer has its output terminals connected to the first output port and the first terminal of the third switch module, respectively, for stepping down the second power supply AC to the third power supply AC and stepping up the second charging AC to the first charging AC;

[0010] The second switch module has a first end connected to the second power battery and a second end connected to the DC end of the second inverter module and the DC end of the second auxiliary transformer module.

[0011] The second inverter module has its AC terminal connected to the second traction motor and is used to convert the second power supply DC power into the second power supply AC power to power the second traction motor.

[0012] The second auxiliary transformer module has its AC terminal connected to the input terminal of the second transformer. It is used to convert the second power supply DC to the third power supply AC and the third charging AC to the second charging DC.

[0013] The second transformer has its output terminals connected to the second output port and the first terminal of the third switch module, respectively, and is used to step down the third power supply AC to the fourth power supply AC; and to step up the second charging AC to the third charging AC.

[0014] The third switch module has its second end connected to the charging port.

[0015] Optionally, the first switch module includes:

[0016] The first switch has its first end connected to the first power battery and its second end connected to the positive DC terminal of the first inverter module and the positive DC terminal of the first auxiliary transformer module, respectively.

[0017] The second switch has its first end connected to the first power battery and its second end connected to the first end of the first current-limiting resistor.

[0018] The second end of the first current-limiting resistor is connected to the positive DC terminal of the first inverter module and the positive DC terminal of the first auxiliary transformer module, respectively.

[0019] Optionally, the second switch module includes:

[0020] The third switch has its first end connected to the second power battery and its second end connected to the positive DC terminal of the second inverter module and the positive DC terminal of the second auxiliary transformer module, respectively.

[0021] The fourth switch has its first end connected to the second power battery and its second end connected to the first end of the second current-limiting resistor.

[0022] The second end of the second current-limiting resistor is connected to the positive DC terminal of the second inverter module and the positive DC terminal of the second auxiliary transformer module, respectively.

[0023] The third switch module includes:

[0024] The fifth switch has its first end connected to the second end of the first transformer and the second end of the second transformer, and its second end connected to the charging port.

[0025] The sixth switch has its first terminal connected to the second terminal of the first transformer and the second terminal of the second transformer, and its second terminal connected to the first terminal of the third current-limiting resistor.

[0026] The third current-limiting resistor has its second end connected to the charging port.

[0027] Optionally, it also includes:

[0028] The seventh switch has its first end connected to the AC terminal of the first auxiliary transformer module, and its second end connected to the first terminal of the first transformer and the first terminal of the eighth switch.

[0029] The eighth switch, the second terminal of which is connected to the AC terminal of the second auxiliary transformer module;

[0030] The ninth switch has its first end connected to the second end of the eighth switch and the AC end of the second auxiliary transformer module, and its second end is connected to the first end of the second transformer.

[0031] The tenth switch has its first end connected to the second end of the first transformer and the input end of the third switch module, and its second end connected to the second end of the second transformer and the second output port.

[0032] Optionally, it also includes:

[0033] The eleventh switch has its first end connected to the first power battery and its second end connected to the second power battery.

[0034] Optionally, it also includes:

[0035] The circuit breaker has its first terminal connected to the first terminal of the first transformer and its second terminal connected to the charger.

[0036] The charger has its second end connected to a DC load, which is used to convert the AC power from the third power supply into DC power to power the DC load.

[0037] Optionally, it also includes:

[0038] The first filter module has its first end connected to the first power battery and its second end connected to the input terminal of the first switch module.

[0039] And / or, a second filter module, the first end of which is connected to the second power battery, and the second end of which is connected to the input terminal of the second switch module.

[0040] Optionally, it also includes:

[0041] The first capacitor has its first end connected to the positive DC terminal of the first inverter module and its second end connected to the negative DC terminal of the first inverter module.

[0042] The second capacitor has its first end connected to the positive DC terminal of the first auxiliary transformer module and its second end connected to the negative DC terminal of the first auxiliary transformer module.

[0043] The third capacitor has its first end connected to the positive DC terminal of the second inverter module and its second end connected to the negative DC terminal of the second inverter module.

[0044] The fourth capacitor has its first end connected to the positive DC terminal of the second auxiliary transformer module and its second end connected to the negative DC terminal of the second auxiliary transformer module.

[0045] Optionally, it also includes:

[0046] The fourth resistor has its first end connected to the positive DC terminal of the first inverter module, and its second end connected to the first end of the fifth resistor and the first end of the fifth capacitor, with the common terminal of the connection grounded.

[0047] The fifth resistor has its second end connected to the negative DC terminal of the first inverter module;

[0048] The first voltage sensor has its input terminal connected to both ends of the fourth resistor and its output terminal connected to the traction control unit, and is used to collect the voltage across the fourth resistor.

[0049] The fifth capacitor has its second terminal connected to the negative DC terminal of the first inverter module.

[0050] The sixth resistor has its first end connected to the positive DC terminal of the second inverter module, and its second end connected to the first end of the seventh resistor and the first end of the sixth capacitor, with the common terminal of the connection grounded.

[0051] The seventh resistor has its second terminal connected to the negative DC terminal of the second inverter module.

[0052] The second voltage sensor has its input terminal connected to both ends of the sixth resistor and its output terminal connected to the traction control unit, and is used to collect the voltage across the sixth resistor.

[0053] The sixth capacitor has its second terminal connected to the negative DC terminal of the second inverter module.

[0054] A fourth voltage sensor, the input terminal of which is connected to the DC terminal of the first inverter module and the output terminal of which is connected to the traction control unit, is used to measure the voltage at the DC terminal of the first inverter module.

[0055] The sixth voltage sensor has its input terminal connected to the DC terminal of the second inverter module and its output terminal connected to the traction control unit, and is used to measure the voltage at the DC terminal of the second inverter module.

[0056] The traction control unit is used to determine whether there is a grounding fault at the DC or AC terminal of the first inverter module based on the voltage collected by the first voltage sensor and the voltage collected by the fourth voltage sensor, and to determine whether there is a grounding fault at the DC or AC terminal of the second inverter module based on the voltage collected by the second voltage sensor and the voltage collected by the sixth voltage sensor.

[0057] Optionally, it also includes:

[0058] The third voltage sensor has its input end connected to both ends of the first power battery and its output end connected to the traction control unit. It is used to measure the voltage at both ends of the first power battery.

[0059] The first current sensor has its input end connected to the second end of the first switch module and its output end connected to the traction control unit. It is used to measure the current flowing through the first current sensor itself.

[0060] The fourth voltage sensor has its input terminal connected to the DC terminal of the first inverter module and its output terminal connected to the traction control unit. It is used to measure the voltage at the DC terminal of the first inverter module.

[0061] The fifth voltage sensor has its input end connected to both ends of the second power battery and its output end connected to the traction control unit. It is used to measure the voltage at both ends of the second power battery.

[0062] The second current sensor has its input end connected to the second end of the second switch module and its output end connected to the traction control unit. It is used to measure the current flowing through the second current sensor itself.

[0063] The sixth voltage sensor has its input terminal connected to the DC terminal of the second inverter module and its output terminal connected to the traction control unit. It is used to measure the voltage at the DC terminal of the second inverter module.

[0064] The traction control unit is used to determine overvoltage and undervoltage of the first power battery based on the voltage collected by the third voltage sensor; to control the first inverter module based on the voltage collected by the fourth voltage sensor; to control the current during the charging process of the first power battery and to determine overcurrent faults based on the current flowing through the first current sensor; to determine overvoltage and undervoltage of the second power battery based on the voltage collected by the fifth voltage sensor; to control the second inverter module based on the voltage collected by the sixth voltage sensor; and to control the current during the charging process of the second power battery and to determine overcurrent faults based on the current flowing through the second current sensor.

[0065] Optionally, it also includes:

[0066] The phase sequence detection port is connected to the charging port and is used to measure the voltage phase sequence of the charging port.

[0067] Optionally, it also includes:

[0068] The cooling system is used to cool the first auxiliary transformer module and the second auxiliary transformer module, the first inverter module and the second inverter module, the first transformer and the second transformer during power supply and charging.

[0069] Optionally, the cooling system includes:

[0070] A water-circulating cooling system is used to cool the first inverter module, the second inverter module, the first auxiliary transformer module, and the second auxiliary transformer module during power supply and charging.

[0071] The air circulation cooling system is used to cool the first and second transformers during power supply and charging.

[0072] Optionally, it also includes:

[0073] The traction control unit is used to control the first auxiliary transformer module and the second auxiliary transformer module during the charging process of the first power battery and the second power battery, so that the harmonic components of the AC terminal of the first auxiliary transformer module cancel out the harmonic components of the AC terminal of the second auxiliary transformer module.

[0074] As can be seen from the above, the present invention provides a traction converter, including a first switching module, a second switching module, a third switching module, a first inverter module, a second inverter module, a first auxiliary transformer module, a second auxiliary transformer module, a first transformer, and a second transformer. When powered by a power battery, the first power battery sequentially powers the first traction motor through the first switching module and the first inverter module, and powers the auxiliary load through the first auxiliary transformer module and the first transformer. Similarly, the second power battery sequentially powers the second traction motor through the second switching module and the second inverter module, and powers the auxiliary load through the second auxiliary transformer module and the second transformer. When charging the power battery, the first power battery is powered through the charging port, the first transformer, and the first auxiliary transformer module, and the second power battery is charged through the charging port, the second transformer, and the second auxiliary transformer module. During normal charging and power supply of the power battery, the first and second auxiliary transformer modules, as well as the first and second transformers, are reused, eliminating the need for additional charging circuits for the first and second power batteries, thereby reducing the size and cost of the traction converter. Attached Figure Description

[0075] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0076] Figure 1 A schematic diagram of the structure of a traction converter provided by the present invention;

[0077] Figure 2 A schematic diagram of the specific circuit structure of a traction converter provided by the present invention;

[0078] Figure 3 A schematic diagram of the forward power supply of a traction converter provided by the present invention;

[0079] Figure 4 This invention provides a schematic diagram of reverse power supply for a traction converter;

[0080] Figure 5 This invention provides a forward power supply energy transmission path diagram for a traction converter;

[0081] Figure 6 This invention provides another forward power supply energy transmission path diagram for a traction converter;

[0082] Figure 7 This invention provides another forward power supply energy transmission path diagram for a traction converter;

[0083] Figure 8 This invention provides another forward power supply energy transmission path diagram for a traction converter;

[0084] Figure 9 This invention provides a reverse power supply energy transmission path diagram for a traction converter;

[0085] Figure 10 Another reverse power supply energy transmission path diagram for a traction converter provided by the present invention;

[0086] Figure 11 Another reverse power supply energy transmission path diagram for a traction converter provided by the present invention;

[0087] Figure 12 This invention provides another reverse power supply energy transmission path diagram for a traction converter. Detailed Implementation

[0088] The core of this invention is to provide a traction converter that, when the power battery is charging and supplying power normally, enables the reuse of the first auxiliary transformer module and the second auxiliary transformer module, as well as the first transformer and the second transformer, eliminating the need for additional charging circuits for the first and second power batteries, thereby reducing the size and cost of the traction converter.

[0089] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0090] Please refer to Figure 1 and Figure 2 ,in, Figure 1 A schematic diagram of the structure of a traction converter provided by the present invention; Figure 2 A schematic diagram of the specific circuit structure of a traction converter provided by the present invention.

[0091] The traction converter includes:

[0092] The first switch module 1 has a first end connected to the first power battery and a second end connected to the DC end of the first inverter module 3 and the DC end of the first auxiliary transformer module 4, respectively.

[0093] The first inverter module 3 has its AC terminal connected to the first traction motor and is used to convert the first power supply DC power into the first power supply AC power to power the first traction motor.

[0094] The first auxiliary transformer module 4 has its AC terminal connected to the input terminal of the first transformer T11, and is used to convert the first power supply DC to the second power supply AC and the first charging AC to the first charging DC.

[0095] The first transformer T11 has its output terminals connected to the first output port and the first terminal of the third switch module 7, respectively, and is used to step down the second power supply AC to the third power supply AC and step up the second charging AC to the first charging AC.

[0096] The first switch module 2 has its first end connected to the second power battery and its second end connected to the DC end of the second inverter module 6 and the DC end of the second auxiliary transformer module 5, respectively.

[0097] The second inverter module 6 has its AC terminal connected to the second traction motor and is used to convert the second power supply DC power into the second power supply AC power to power the second traction motor.

[0098] The second auxiliary transformer module 5 has its AC terminal connected to the input terminal of the second transformer T21. It is used to convert the second power supply DC to the third power supply AC and the third charging AC to the second charging DC.

[0099] The second transformer T21 has its output terminals connected to the second output port and the first terminal of the third switch module 7, respectively, and is used to step down the third power supply AC to the fourth power supply AC; and to step up the second charging AC to the third charging AC.

[0100] The third switch module 7 has its second end connected to the charging port.

[0101] It is understandable that when the train is in motion, the power battery on the train supplies power to the traction motor and auxiliary loads in the forward direction, and when the train is stopped, the external power source charges the power battery in the reverse direction through the charging port.

[0102] Specifically, when the first power battery is supplying power, the first switch module 1 is turned on, and the first inverter module 3 converts the first power supply DC to the first power supply AC to power the first traction motor. At the same time, the first auxiliary transformer module 4 converts the first power supply DC to the second power supply AC, and the first transformer T11 steps down the second power supply AC to the third power supply AC to power the first auxiliary load. Correspondingly, when the second power battery is supplying power, the first switch module 2 is turned on, and the second inverter module 6 converts the second power supply DC to the second power supply AC to power the second traction motor. At the same time, the second auxiliary transformer module 5 converts the second power supply DC to the third power supply AC, and the second transformer T21 steps down the third power supply AC to the fourth power supply AC to power the second auxiliary load. When an external power source reverse charges the power battery through the charging port, the third switch module 7 is turned on, the first transformer T11 boosts the second charging AC power to the first charging AC power, and the first auxiliary transformer module 4 converts the first charging AC power to the first charging DC power to charge the first power battery; similarly, when the third switch module 7 is turned on, the second transformer T21 boosts the second charging AC power to the third charging AC power, and the second auxiliary transformer module 5 converts the third charging AC power to the second charging DC power to charge the second power battery.

[0103] It should be noted that when powered by the power batteries, the first power battery can provide 380V AC power to the first auxiliary load through the traction converter; the second power battery can provide 380V AC power to the second auxiliary load through the traction converter. The first power supply AC power is VVVF (Variable Voltage and Variable Frequency), and the second power supply AC power is CVCF (Constant Voltage and Constant Frequency). When an external power source charges the power batteries in reverse through the charging port, the external power source can provide 380V AC power to the first and second power batteries in reverse through the charging port, transformer, and auxiliary transformer module. The 380V AC power at the charging port can be sourced from the internal power supply.

[0104] It should also be noted that, in addition to the functions of stepping up and stepping down voltage, the first transformer T11 and the second transformer T21 here also have the function of filtering.

[0105] Based on the structure of this application, fuel cells or other power supply systems can be respectively set on the first and second power batteries, and the back-end circuit design is completely identical except for the power battery. When the power battery is undervoltage, the fuel cell continues to supply power to the traction motor and auxiliary loads through the traction converter to ensure uninterrupted power supply to the traction converter. In addition, based on the structure of this application, a set of inverter output and auxiliary transformer output can be connected in parallel at the inverter module 3 and the auxiliary transformer module respectively to supply power to the train's traction motor and auxiliary loads.

[0106] As can be seen from the above, when the external power source is charging the power battery normally and supplying power to the power battery, the reuse of the first auxiliary transformer module 4 and the second auxiliary transformer module 5, the first transformer T11 and the second transformer T21 is realized, and there is no need to set up additional charging circuits for the first power battery and the second power battery, thereby reducing the size and cost of the traction converter.

[0107] Based on the above embodiments:

[0108] As an optional embodiment, the first switch module 1 includes:

[0109] The first switch KM12 has its first end connected to the first power battery and its second end connected to the DC positive terminal of the first inverter module 3 and the DC positive terminal of the first auxiliary transformer module 4, respectively.

[0110] The second switch KM11 has its first end connected to the first power battery and its second end connected to the first end of the first current-limiting resistor R11.

[0111] The second end of the first current-limiting resistor R11 is connected to the DC positive terminal of the first inverter module 3 and the DC positive terminal of the first auxiliary transformer module 4, respectively.

[0112] It should be noted that, considering that the current will increase instantaneously when the power battery supplies power to the traction motor and auxiliary load, which may damage the components in the circuit, this application sets up a pre-charging circuit in the circuit to prevent damage to the components in the circuit during the power supply instant.

[0113] In this application, the first switch module 1 includes a first switch KM12, a second switch KM11, and a first current-limiting resistor R11. Based on this structure, when the first power battery supplies power to the first traction motor and auxiliary load, the traction control unit first controls the second switch KM11 to close and the first switch KM12 to open. At this time, the supply current passes through the first current-limiting resistor R11, thereby reducing the supply current to the first traction motor and auxiliary load, and realizing the pre-charging of the first capacitor C11 and the second capacitor C12. After the pre-charging is completed, the traction control unit controls the second switch KM11 to open and the first switch KM12 to close. At this time, the first traction motor and auxiliary load are supplied through the first switch KM12.

[0114] It is evident that this method ensures a stable power supply current for both the first traction motor and the auxiliary load throughout the entire power supply process.

[0115] As an optional embodiment, the first switch module 2 includes:

[0116] The third switch KM22 has its first end connected to the second power battery and its second end connected to the positive DC terminal of the second inverter module 6 and the positive DC terminal of the second auxiliary transformer module 5, respectively.

[0117] The fourth switch KM21 has its first terminal connected to the second power battery and its second terminal connected to the first terminal of the second current-limiting resistor R21.

[0118] The second end of the second current-limiting resistor R21 is connected to the positive DC terminal of the second inverter module 6 and the positive DC terminal of the second auxiliary transformer module 5, respectively.

[0119] It should be noted that, considering that the current of the power battery will increase instantaneously when supplying power to the traction motor and auxiliary load, which may damage the components in the circuit, this application sets up a pre-charging circuit in the circuit to prevent damage to the components in the circuit during the instantaneous power supply.

[0120] In this application, the first switch module 2 includes a third switch KM22, a fourth switch KM21, and a second current-limiting resistor R21. Based on this structure, when the second power battery supplies power to the second traction motor through the first inverter module 3, the traction control unit first controls the fourth switch KM21 to close and the second switch KM11 to open. At this time, the supply current passes through the second current-limiting resistor R21, thereby reducing the supply current to the second traction motor and realizing the pre-charging of the voltage regulator capacitor. After the pre-charging is completed, the traction control unit controls the fourth switch KM21 to open and the third switch KM22 to close, at which time the second traction motor is supplied with power through the third switch KM22.

[0121] It is evident that this method ensures a stable power supply current for the second traction motor and auxiliary load throughout the entire power supply process.

[0122] As an optional embodiment, the third switch module 7 includes:

[0123] The fifth switch Kc2 has its first end connected to the second end of the first transformer T11 and the second end of the second transformer T21, and its second end is connected to the charging port.

[0124] The sixth switch Kc1 has its first end connected to the second end of the first transformer T11 and the second end of the second transformer T21, and its second end connected to the first end of the third current-limiting resistor Rc.

[0125] The third current-limiting resistor Rc has its second end connected to the charging port.

[0126] It should be noted that when the power battery is charged in reverse, the current will increase instantaneously upon power-on. This can easily generate a large surge current in the charging circuit between the second transformer T21 and the second auxiliary transformer module 5, which may damage the components in the circuit. To prevent this problem, this application has set up a pre-charging circuit at the charging port to prevent damage to the components in the circuit during charging.

[0127] In this application, the third switch module 7 includes a fifth switch Kc2, a sixth switch Kc1, and a third current-limiting resistor Rc. Based on this structure, an external power supply outputs 380V AC power through the charging port to charge the first and second power batteries. The traction control unit first controls the sixth switch Kc1 to close. At this time, the charging current passes through the third current-limiting resistor Rc, thereby reducing the charging current of the first and second power batteries and realizing the pre-charging of the second capacitor C12 and the fourth capacitor C22. After the pre-charging is completed, the traction control unit controls the sixth switch Kc1 to open and controls the fifth switch Kc2 to close. At this time, the first and second power batteries are charged through the fifth switch Kc2.

[0128] Please refer to Figure 3 and Figure 4 , Figure 3 A schematic diagram of forward power supply for a traction converter provided by the present invention; Figure 4 This invention provides a schematic diagram of a traction converter with reverse power supply.

[0129] As an optional embodiment, it also includes:

[0130] The seventh switch K1 has its first end connected to the AC terminal of the first auxiliary transformer module 4, and its second end connected to the first terminal of the first transformer T11 and the first terminal of the eighth switch K2.

[0131] The eighth switch K2, the second end of the eighth switch K2 is connected to the AC terminal of the second auxiliary transformer module 5;

[0132] The first end of the ninth switch K3 is connected to the second end of the eighth switch K2 and the AC end of the second auxiliary transformer module 5, and the second end is connected to the first end of the second transformer T21.

[0133] The tenth switch K4 has its first end connected to the second end of the first transformer T11 and the input end of the third switch module 7, and its second end connected to the second end of the second transformer T21 and the second output port.

[0134] It should be noted that when the first power battery is supplying power, the first inverter module 3 converts the first DC power supply to the first AC power supply to power the first traction motor. Simultaneously, the first auxiliary transformer module 4 converts the first DC power supply to the second AC power supply. The seventh switch K1 closes, and the first transformer T11 steps down the second AC power supply to the third AC power supply. The charger then converts the third AC power supply back to DC power to power the DC loads and train auxiliary loads. Correspondingly, when the second power battery is supplying power, the second inverter module 6 converts the second DC power supply to the second AC power supply to power the second traction motor. Simultaneously, the second auxiliary transformer module 5 converts the second DC power supply to the third AC power supply. The ninth switch K3 closes, and the second transformer T21 steps down the third AC power supply to the fourth AC power supply to power the train auxiliary loads.

[0135] When the external power supply charges the first and second power batteries in reverse through the charging port, the seventh switch K1 and the ninth switch K3 are closed. The first transformer T11 boosts the second charging AC power to the first charging AC power, and the first auxiliary transformer module 4 converts the first charging AC power to the first charging DC power to charge the first power battery. At the same time, the second transformer T21 boosts the second charging AC power to the third charging AC power, and the second auxiliary transformer module 5 converts the third charging AC power to the second charging DC power to charge the second power battery. Please refer to Table 1 for details. Table 1 is a forward charging redundancy design specification table.

[0136] Table 1. Forward Power Supply Redundancy Design Specifications

[0137]

[0138] Please refer to Figure 5 , Figure 5 This invention provides a forward power supply energy transmission path diagram for a traction converter.

[0139] When the power battery is supplying power to the traction motor and auxiliary loads in the forward direction, if the first auxiliary transformer module 4 fails, the seventh switch K1 can be disconnected and the eighth switch K2 and the ninth switch K3 can be closed. The first power battery can supply power to the first traction motor through the first inverter module 3, and the second power battery can supply power to the second traction motor. In addition, the second power battery can also supply power to the auxiliary loads through the second auxiliary transformer module 5 and the second transformer T21, supply power to the auxiliary loads through the first transformer T11, and supply power to the DC loads of the train through the charger.

[0140] Reference Figure 6 , Figure 6 This invention provides another forward power supply energy transmission path diagram for a traction converter.

[0141] If the second auxiliary transformer module 5 fails, the seventh switch K1, the eighth switch K2 and the ninth switch K3 are closed. The first power battery supplies power to the first traction motor, supplies power to the auxiliary load through the first auxiliary transformer module 4 and the first transformer T11, supplies power to the DC load through the charger, and supplies power to the auxiliary load through the second transformer T21; the second power battery supplies power to the second traction motor.

[0142] Reference Figure 7 , Figure 7 This invention provides another forward power supply energy transmission path diagram for a traction converter.

[0143] If the first auxiliary transformer module 4 and the first transformer T11 fail, the seventh switch K1 and the eighth switch K2 are disconnected, and the ninth switch K3 and the tenth switch K4 are closed. The first power battery supplies power to the first traction motor, the second power battery supplies power to the second traction motor, and supplies power to the auxiliary load through the second auxiliary transformer module 5 and the second transformer T21, supplies power to the auxiliary load through the tenth switch K4, and supplies power to the DC load through the charger.

[0144] Reference Figure 8 , Figure 8 This invention provides another forward power supply energy transmission path for a traction converter.

[0145] If the second auxiliary transformer module 5 and the second transformer T21 fail, disconnect the eighth switch K2 and the ninth switch K3, and close the seventh switch K1 and the tenth switch K4. The first power battery supplies power to the auxiliary load through the first auxiliary transformer module 4 and the first transformer T11, and supplies power to the DC load through the charger, and supplies power to the auxiliary load through the tenth switch K4. Please refer to Table 2 for details. Table 2 is the reverse charging redundancy design specification table.

[0146] Table 2 Reverse Charging Redundancy Design Specifications

[0147]

[0148] As an optional embodiment, it also includes:

[0149] The eleventh switch Kd has its first end connected to the first power battery and its second end connected to the second power battery.

[0150] Please refer to Figure 9 , Figure 9 This invention provides a reverse power supply energy transmission path diagram for a traction converter.

[0151] The external power supply is reversed to charge the first and second power batteries. If the first auxiliary transformer module 4 fails, the seventh switch K1 and the eighth switch K2 are disconnected, and the ninth switch K3, the tenth switch K4 and the eleventh switch Kd are closed. The first and second power batteries are then charged through the second transformer T21 and the second auxiliary transformer module 5.

[0152] Please refer to Figure 10 , Figure 10 This invention provides another reverse power supply energy transmission path diagram for a traction converter.

[0153] If the second auxiliary transformer module 5 fails, disconnect the eighth switch K2, the ninth switch K3, and the tenth switch K4, and close the seventh switch K1 and the eleventh switch Kd to charge the first power battery and the second power battery through the first transformer T11 and the first auxiliary transformer module 4.

[0154] Please refer to Figure 11 , Figure 11 This invention provides another reverse power supply energy transmission path diagram for a traction converter.

[0155] If the first transformer T11 fails, disconnect the eleventh switch Kd and close the seventh switch K1, the eighth switch K2, the ninth switch K3 and the tenth switch K4. The first power battery can be charged through the second transformer T21, and then through the first auxiliary transformer module 4, and the second power battery can be charged through the second auxiliary transformer module 5.

[0156] Please refer to Figure 12 , Figure 12 This invention provides another reverse power supply energy transmission path diagram for a traction converter.

[0157] If the second transformer T21 fails, disconnect the ninth switch K3, the tenth switch K4 and the fifth circuit breaker, and close the seventh switch K1 and the eighth switch K2. The first power battery can be charged through the first transformer T11, then through the first auxiliary transformer module 4, and then through the second auxiliary transformer module 5.

[0158] As an optional embodiment, it also includes:

[0159] The circuit breaker has its first terminal connected to the first terminal of the first transformer T11 and its second terminal connected to the charger.

[0160] The charger has its second end connected to a DC load, which is used to convert the AC power from the third power supply into DC power to power the DC load.

[0161] Understandably, when the first auxiliary transformer module 4 fails, the eighth switch K2 and the sixth circuit breaker close. The second power battery can then supply the charger with third AC power through the second auxiliary transformer module 5, the eighth switch K2, and the first transformer T11. The charger converts this third AC power into DC power to supply the DC loads in the train. When the second auxiliary transformer module 5 fails, the seventh switch K1 closes. The first power battery can then supply the charger with third AC power through the first auxiliary transformer module 4, the seventh switch K1, and the first transformer T11. The charger converts this third AC power into DC power to supply the DC loads in the train. The system provides AC power to the charger via the second auxiliary power module 5 and the first transformer T11. When the first auxiliary power module 4 and the first transformer T11 fail, the ninth switch K3, the tenth switch K4 and the circuit breaker close, and the second power supply provides the charger with the fourth AC power through the second auxiliary power module 5 and the second transformer T21. The charger converts the fourth AC power to DC power to supply the train load. When the second auxiliary power module 5 and the second transformer T21 fail, the seventh switch K1 closes, and the first power battery provides the charger with the third AC power through the first auxiliary power module 4 and the first transformer T11. The charger converts the third AC power to DC power to supply the train's DC load.

[0162] It should be noted that the charger's DC output port has two positive lines and one negative line, outputting 110V DC power to supply power to the vehicle's DC load.

[0163] As an optional embodiment, it also includes:

[0164] The first filter module Lm11 has its first end connected to the first power battery and its second end connected to the input terminal of the first switch module 1.

[0165] And / or, the second filter module Lm21, the first end of the second filter module Lm21 is connected to the second power battery, and the second end is connected to the input end of the first switch module 2.

[0166] In this application, the first filter module Lm11 and the second filter module Lm21 are inductors. The first filter module Lm11 is disposed between the first power battery and the first switch module 1 to suppress noise at the output voltage of the first power battery, reduce the current ripple when charging the first power battery, and further improve the reliability of the power battery power supply. The second filter module Lm21 is disposed between the second power battery and the first switch module 2 to suppress noise at the output voltage of the second power battery, reduce the current ripple when charging the second power battery, and further improve the reliability of the power battery power supply.

[0167] As can be seen, this application uses a first filter module Lm11 and / or a second filter module Lm21 to suppress noise in the power supply voltage, thereby further improving the reliability of the power supply voltage provided to the traction motor and auxiliary load.

[0168] As an optional embodiment, it also includes:

[0169] The first capacitor C11 has its first end connected to the positive DC terminal of the first inverter module 3, and its second end connected to the negative DC terminal of the first inverter module 3.

[0170] The second capacitor C12 has its first end connected to the positive DC terminal of the first auxiliary transformer module 4, and its second end connected to the negative DC terminal of the first auxiliary transformer module 4.

[0171] The third capacitor C21 has its first end connected to the positive DC terminal of the second inverter module 6 and its second end connected to the negative DC terminal of the second inverter module 6.

[0172] The fourth capacitor C22 has its first end connected to the positive DC terminal of the second auxiliary transformer module 5, and its second end connected to the negative DC terminal of the second auxiliary transformer module 5.

[0173] Considering that the voltage fluctuations in the entire power supply circuit are large during the power battery supply process, which may damage the components in the circuit, this application sets up a first capacitor C11, a second capacitor C12, a third capacitor C21 and a fourth capacitor C22 to suppress the voltage fluctuations in the circuit, so that the voltage on the circuit is smoother.

[0174] As an optional embodiment, it also includes:

[0175] The fourth resistor R12 has its first end connected to the DC positive terminal of the first inverter module 3, and its second end connected to the first end of the fifth resistor R13 and the first end of the fifth capacitor, respectively, with the common terminal of the connection grounded.

[0176] The fifth resistor R13 has its second end connected to the negative DC terminal of the first inverter module 3.

[0177] The first voltage sensor VH13 has its input terminal connected to both ends of the fourth resistor R12 and its output terminal connected to the traction control unit, and is used to collect the voltage across the fourth resistor R12.

[0178] The fifth capacitor has its second terminal connected to the negative DC terminal of the first inverter module 3.

[0179] The sixth resistor R22 has its first end connected to the DC positive terminal of the second inverter module 6, and its second end connected to the first end of the seventh resistor R23 and the first end of the sixth capacitor, respectively, with the common terminal of the connection grounded.

[0180] The seventh resistor R23 has its second end connected to the negative DC terminal of the second inverter module 6.

[0181] The second voltage sensor VH23 has its input terminal connected to both ends of the sixth resistor R22 and its output terminal connected to the traction control unit. It is used to collect the voltage across the sixth resistor R22.

[0182] The sixth capacitor has its second terminal connected to the negative DC terminal of the second inverter module 6.

[0183] The fourth voltage sensor VH12 has its input terminal connected to the DC terminal of the first inverter module 3 and its output terminal connected to the traction control unit. It is used to measure the voltage at the DC terminal of the first inverter module 3.

[0184] The sixth voltage sensor VH22 has its input terminal connected to the DC terminal of the second inverter module 6 and its output terminal connected to the traction control unit. It is used to measure the voltage at the DC terminal of the second inverter module 6.

[0185] The traction control unit is used to determine whether there is a grounding fault at the DC or AC terminal of the first inverter module based on the voltage collected by the first voltage sensor VH13 and the voltage collected by the fourth voltage sensor VH12, and to determine whether there is a grounding fault at the DC or AC terminal of the second inverter module based on the voltage collected by the second voltage sensor VH23 and the voltage collected by the sixth voltage sensor VH22.

[0186] Considering that the power battery may experience a grounding fault when it is supplying power in the forward direction, this application sets up a fourth resistor R12, a fifth resistor R13, a first voltage sensor VH13, and a fourth voltage sensor VH12 in the primary power supply circuit. The traction control unit determines whether the DC positive terminal, DC negative terminal, or AC terminal of the first inverter module is grounded. In the secondary power supply circuit, a sixth resistor R22, a seventh resistor R23, a second voltage sensor VH23, and a sixth voltage sensor VH22 are set up. The traction control unit then determines whether the DC positive terminal, DC negative terminal, or AC terminal of the second inverter module is grounded.

[0187] It should be noted that the first terminals of the fifth and sixth capacitors are grounded, which can filter out the AC components mixed in with the DC current through the characteristic of passing AC and blocking DC.

[0188] As can be seen, by setting up the first voltage sensor VH13 and the fourth voltage sensor VH12, the voltage values ​​collected by the two voltage sensors are compared to determine whether there is a grounding fault at the DC or AC terminal of the first inverter module 3. Similarly, by setting up the second voltage sensor VH23 and the sixth voltage sensor VH22, the voltage values ​​collected by the two voltage sensors are compared to determine whether there is a grounding fault at the DC or AC terminal of the second inverter module 6. After filtering by the fifth and sixth capacitors, a smoother DC current can be obtained, making the filtered voltage more accurate and improving the efficiency of power supply from the power battery.

[0189] As an optional embodiment, it also includes:

[0190] The third voltage sensor VH11 has its input terminal connected to both ends of the first power battery and its output terminal connected to the traction control unit. It is used to measure the voltage across the first power battery.

[0191] The first current sensor LH11 has its input terminal connected to the second terminal of the first switch module 1 and its output terminal connected to the traction control unit. It is used to measure the current flowing through the first current sensor LH11 itself.

[0192] The fourth voltage sensor VH12 has its input terminal connected to the DC terminal of the first inverter module 3 and its output terminal connected to the traction control unit. It is used to measure the voltage at the DC terminal of the first inverter module 3.

[0193] The fifth voltage sensor VH21 has its input terminal connected to both ends of the second power battery and its output terminal connected to the traction control unit. It is used to measure the voltage across the second power battery.

[0194] The second current sensor LH21 has its input terminal connected to the second terminal of the second switch module 2 and its output terminal connected to the traction control unit. It is used to measure the current flowing through the second current sensor LH21 itself.

[0195] The sixth voltage sensor VH22 has its input terminal connected to the DC terminal of the second inverter module 6 and its output terminal connected to the traction control unit. It is used to measure the voltage at the DC terminal of the second inverter module 6.

[0196] The traction control unit is used to determine overvoltage and undervoltage of the first power battery based on the voltage collected by the third voltage sensor VH11, and to control the first inverter module 3 based on the voltage collected by the fourth voltage sensor VH12; to control the current during the charging process of the first power battery and to determine overcurrent faults based on the current flowing through the first current sensor LH11; to determine overvoltage and undervoltage of the second power battery based on the voltage collected by the fifth voltage sensor VH21; to control the second inverter module 6 based on the voltage collected by the sixth voltage sensor VH22; and to control the current during the charging process of the second power battery and to determine overcurrent faults based on the current flowing through the second current sensor LH21.

[0197] Understandably, when the first power battery is supplying power, the third voltage sensor VH11 measures the voltage across the first power battery, and the traction control unit determines whether the first power battery is in an undervoltage state. When charging the first power battery, the third voltage sensor VH11 measures the voltage across the first power battery, and the traction control unit determines whether the first power battery is in an overvoltage state. A fourth voltage sensor VH12 is provided to control the AC side voltage of the first inverter module 3 to obtain the voltage value of the first power supply DC. After conversion by the first inverter module 3, the first power supply DC is converted into first power supply AC to provide suitable AC power for the first traction motor. Similarly, a sixth voltage sensor VH22 is provided to control the AC side voltage of the second inverter module 6 to obtain the voltage value of the second power supply DC. After conversion by the second inverter module 6, the second power supply DC is converted into second power supply AC to provide suitable AC power for the second traction motor.

[0198] Understandably, when the external power source is charging the first power battery through the charging port, the first current sensor LH11 can be used to measure the current flowing through it, constantly monitoring the charging current of the first power battery. If the measured value is greater than the current of the first power battery, the traction control unit will stop charging the first power battery. Similarly, the second current sensor LH21 can be used to measure the current flowing through it, constantly monitoring the charging current of the second power battery. If the measured value is greater than the current of the second power battery, the traction control unit will stop charging the second power battery.

[0199] It is evident that when the power battery supplies power and charges the power battery in reverse, the traction control unit judges the power battery for undervoltage and overvoltage faults based on the voltage sensor, and judges the power battery for overcurrent faults based on the measurement value of the current sensor. After judging the fault, the traction control unit promptly takes corresponding control measures, which can protect the power battery to a certain extent.

[0200] As an optional embodiment, it also includes:

[0201] The phase sequence detection port is connected to the charging port and is used to measure the voltage phase sequence of the charging port.

[0202] It is understandable that when the external power source is charging the power battery, the two charging circuits will share a charging port to charge simultaneously. A phase sequence detection port is set at the charging port to measure the phase sequence of the voltage input to the charging port.

[0203] It is evident that measuring the voltage phase sequence at the input of the charging port by the phase sequence detection port during power battery charging improves the charging efficiency to some extent.

[0204] As an optional embodiment, it also includes:

[0205] The cooling system is used to cool the first auxiliary transformer module 4 and the second auxiliary transformer module 5, the first inverter module 3 and the second inverter module 6, the first transformer T11 and the second transformer T21 during power supply and charging.

[0206] Understandably, the power battery supplies power to the traction motor and auxiliary load, and the external power supply charges the power battery through the charging port. During this process, the cooling system can ensure that components such as the first auxiliary transformer module 4 and the second auxiliary transformer module 5, the first inverter module 3 and the second inverter module 6, the first transformer T11 and the second transformer T21 do not overheat, and dissipate the heat generated by these devices in a timely manner to protect the normal operation of other components in the circuit.

[0207] It is evident that by installing a cooling system in the main circuit of the traction converter, the cooling system can effectively reduce the temperature of the first auxiliary transformer module 4 and the second auxiliary transformer module 5, the first inverter module 3 and the second inverter module 6, the first transformer T11 and the second transformer T21 during actual operation, ensuring that these devices operate within the ideal temperature range, thereby guaranteeing the performance of the traction converter and the safe operation of the train.

[0208] As an optional embodiment, the cooling system includes:

[0209] A water-circulating cooling system is used to cool the first inverter module 3 and the second inverter module 6, the first auxiliary transformer module 4 and the second auxiliary transformer module 5 during power supply and charging.

[0210] The air circulation cooling system is used to cool the first transformer T11 and the second transformer T21 during power supply and charging.

[0211] It is understandable that, in order to effectively cool the components in the circuit, a wind-circulating cooling system and a water-circulating cooling system can be set up inside the traction converter. The first inverter module 3 and the second inverter module 6, the first auxiliary transformer module 4 and the second auxiliary transformer module 5 are cooled by water circulation, while the first transformer T11 and the second transformer T21 are cooled by wind circulation.

[0212] Specifically, the heat is transferred from the inside of the traction converter to the outside through a water circulation system, and then dissipated to the surrounding environment through a radiator. The water circulation cooling system generally includes components such as a water pump, radiator, and water pipes, which can effectively reduce the temperature of the traction converter, prevent overheating, and ensure that the converter can operate stably under various working conditions. The water circulation cooling system also has the function of preventing scale formation and freezing, further protecting the traction converter from damage. The first transformer T11 and the second transformer T21 are cooled by air circulation. Through air flow or the installation of fans, heat is transferred from the inside of the traction converter to the external environment to achieve the effect of protecting the internal components from overheating.

[0213] It is understandable that the first transformer T11 and the second transformer T21 are cooled by air circulation, which has a relatively simple structure and low cost. On the other hand, the first inverter module 3 and the second inverter module 6, the first auxiliary transformer module 4 and the second auxiliary transformer module 5 are cooled by water circulation. Water flows in a closed circulation system to absorb the heat generated by the devices, which has high heat dissipation efficiency and can meet the heat dissipation requirements of high-power traction converters.

[0214] It is evident that by installing both air-cooled and water-cooled systems in the traction converter, the problem of overheating of various components is not only solved, but the structures of the air-cooled and water-cooled systems are also relatively simple and cost-effective.

[0215] As an optional embodiment, it also includes:

[0216] The traction control unit is used to control the first auxiliary transformer module 4 and the second auxiliary transformer module 5 during the charging process of the first power battery and the second power battery, so that the harmonic components of the AC terminal of the first auxiliary transformer module 4 cancel out the harmonic components of the AC terminal of the second auxiliary transformer module 5.

[0217] Considering that when the external power supply charges the power battery, the two circuits charge simultaneously and share a charging port, which will generate harmonics at the charging port, the traction control unit controls the first auxiliary transformer module 4 and the second auxiliary transformer module 5. There is a phase difference between the first and second circuits, so that the harmonic components of the AC terminal of the first auxiliary transformer module 4 and the harmonic components of the AC power of the second auxiliary transformer module 5 cancel each other out. This achieves phase-shift control of the charging of the two sets of power batteries, thereby reducing input-side harmonics and improving charging efficiency.

[0218] It is evident that when charging the first and second power batteries, the harmonics at the AC terminals of the first auxiliary transformer module 4 and the second auxiliary transformer module 5 are canceled out, thereby reducing harmonics. Furthermore, the requirements for hardware filtering circuits are reduced during harmonic filtering, eliminating the need for additional filtering components and achieving a lightweight design for the traction converter.

[0219] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0220] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A traction converter, characterized in that, include: The first switch module has a first end connected to the first power battery and a second end connected to the DC end of the first inverter module and the DC end of the first auxiliary transformer module, respectively. The first inverter module has its AC terminal connected to the first traction motor and is used to convert the first power supply DC power into the first power supply AC power to power the first traction motor. The first auxiliary transformer module has its AC terminal connected to the input terminal of the first transformer, and is used to convert the first power supply DC current into the second power supply AC current and the first charging AC current into the first charging DC current. The first transformer, whose output terminals are respectively connected to the first output port and the first terminal of the third switch module, is used to step down the second power supply AC to the third power supply AC and step up the second charging AC to the first charging AC; The second switch module has a first end connected to the second power battery and a second end connected to the DC end of the second inverter module and the DC end of the second auxiliary transformer module, respectively. The second inverter module has its AC terminal connected to the second traction motor and is used to convert the second power supply DC power into the second power supply AC power to power the second traction motor. The second auxiliary transformer module has its AC terminal connected to the input terminal of the second transformer, and is used to convert the second power supply DC current into the third power supply AC current, and the third charging AC current into the second charging DC current. The second transformer, whose output terminal is connected to the second output port and the first terminal of the third switch module respectively, is used to step down the third AC power supply to the fourth AC power supply. The second charging AC power is boosted to the third charging AC power; The third switch module has its second end connected to the charging port.

2. The traction converter as described in claim 1, characterized in that, The first switch module includes: A first switch, the first end of which is connected to the first power battery, and the second end of which is connected to the DC positive terminal of the first inverter module and the DC positive terminal of the first auxiliary transformer module respectively; The second switch has a first end connected to the first power battery and a second end connected to the first end of the first current-limiting resistor. The second end of the first current-limiting resistor is connected to the positive DC terminal of the first inverter module and the positive DC terminal of the first auxiliary transformer module, respectively.

3. The traction converter as described in claim 1, characterized in that, The second switch module includes: The third switch has its first end connected to the second power battery and its second end connected to the positive DC terminal of the second inverter module and the positive DC terminal of the second auxiliary transformer module, respectively. The fourth switch has its first end connected to the second power battery and its second end connected to the first end of the second current-limiting resistor. The second end of the second current-limiting resistor is connected to the DC positive terminal of the second inverter module and the DC positive terminal of the second auxiliary transformer module, respectively.

4. The traction converter as described in claim 1, characterized in that, The third switch module includes: The fifth switch has its first end connected to the second end of the first transformer and the second end of the second transformer, and its second end connected to the charging port. The sixth switch has its first end connected to the second end of the first transformer and the second end of the second transformer, and its second end connected to the first end of the third current-limiting resistor. The third current-limiting resistor has its second end connected to the charging port.

5. The traction converter as described in claim 1, characterized in that, Also includes: The seventh switch has its first end connected to the AC terminal of the first auxiliary transformer module, and its second end connected to the first terminal of the first transformer and the first terminal of the eighth switch, respectively. The eighth switch, the second end of the eighth switch is connected to the AC terminal of the second auxiliary transformer module; The ninth switch has its first end connected to the second end of the eighth switch and the AC terminal of the second auxiliary transformer module, and its second end connected to the first end of the second transformer. The tenth switch has its first end connected to the second end of the first transformer and the input end of the third switch module, and its second end connected to the second end of the second transformer and the second output port.

6. The traction converter as described in claim 1, characterized in that, Also includes: The eleventh switch has its first end connected to the first power battery and its second end connected to the second power battery.

7. The traction converter as described in claim 1, characterized in that, Also includes: A circuit breaker, wherein the first end of the circuit breaker is connected to the first end of the first transformer, and the second end is connected to the charger; The charger has a second end connected to a DC load, which is used to convert the third AC power supply into DC power to supply power to the DC load.

8. The traction converter as described in claim 1, characterized in that, Also includes: The first filtering module has a first end connected to the first power battery and a second end connected to the input end of the first switching module. And / or, a second filtering module, wherein the first end of the second filtering module is connected to the second power battery, and the second end is connected to the input end of the second switching module.

9. The traction converter as described in claim 1, characterized in that, Also includes: A first capacitor, with its first end connected to the positive DC terminal of the first inverter module and its second end connected to the negative DC terminal of the first inverter module; The second capacitor has its first end connected to the positive DC terminal of the first auxiliary transformer module and its second end connected to the negative DC terminal of the first auxiliary transformer module. The third capacitor has its first end connected to the positive DC terminal of the second inverter module and its second end connected to the negative DC terminal of the second inverter module. The fourth capacitor has its first end connected to the positive DC terminal of the second auxiliary transformer module and its second end connected to the negative DC terminal of the second auxiliary transformer module.

10. The traction converter as described in claim 1, characterized in that, Also includes: The fourth resistor has its first end connected to the DC positive terminal of the first inverter module, its second end connected to the first end of the fifth resistor and the first end of the fifth capacitor, and the common terminal of the connection is grounded. The fifth resistor, the second end of which is connected to the negative DC terminal of the first inverter module; A first voltage sensor, the input terminal of which is connected to both ends of the fourth resistor, and the output terminal of which is connected to the traction control unit, is used to collect the voltage across the fourth resistor; The fifth capacitor has its second terminal connected to the negative DC terminal of the first inverter module; The sixth resistor has its first end connected to the positive DC terminal of the second inverter module, and its second end connected to the first end of the seventh resistor and the first end of the sixth capacitor, with the common terminal of the connection grounded. The seventh resistor, the second end of which is connected to the negative DC terminal of the second inverter module; The second voltage sensor has its input terminal connected to both ends of the sixth resistor and its output terminal connected to the traction control unit, and is used to collect the voltage across the sixth resistor. The sixth capacitor, the second end of which is connected to the negative DC terminal of the second inverter module; A fourth voltage sensor, the input terminal of which is connected to the DC terminal of the first inverter module and the output terminal of which is connected to the traction control unit, is used to measure the voltage at the DC terminal of the first inverter module. The sixth voltage sensor has its input terminal connected to the DC terminal of the second inverter module and its output terminal connected to the traction control unit, and is used to measure the voltage at the DC terminal of the second inverter module. The traction control unit is used to determine whether there is a grounding fault at the DC or AC terminal of the first inverter module based on the voltage collected by the first voltage sensor and the voltage collected by the fourth voltage sensor, and to determine whether there is a grounding fault at the DC or AC terminal of the second inverter module based on the voltage collected by the second voltage sensor and the voltage collected by the sixth voltage sensor.

11. The traction converter as described in claim 1, characterized in that, Also includes: The third voltage sensor has its input end connected to both ends of the first power battery and its output end connected to the traction control unit, and is used to measure the voltage at both ends of the first power battery. A first current sensor, the input terminal of which is connected to the second terminal of the first switch module, and the output terminal of which is connected to the traction control unit, is used to measure the current flowing through the first current sensor itself; The fourth voltage sensor has its input terminal connected to the DC terminal of the first inverter module and its output terminal connected to the traction control unit, and is used to measure the voltage at the DC terminal of the first inverter module. The fifth voltage sensor has its input terminal connected to both ends of the second power battery and its output terminal connected to the traction control unit, and is used to measure the voltage across the second power battery. The second current sensor has its input terminal connected to the second terminal of the second switch module and its output terminal connected to the traction control unit. It is used to measure the current flowing through the second current sensor itself. The sixth voltage sensor has its input terminal connected to the DC terminal of the second inverter module and its output terminal connected to the traction control unit, and is used to measure the voltage at the DC terminal of the second inverter module. The traction control unit is used to determine overvoltage and undervoltage of the first power battery based on the voltage collected by the third voltage sensor; and to control the first inverter module based on the voltage collected by the fourth voltage sensor. Based on the current flowing through the first current sensor, the current during the charging process of the first power battery is controlled and overcurrent faults are judged. Based on the voltage collected by the fifth voltage sensor, the second power battery is judged to be over-voltage or under-voltage; based on the voltage collected by the sixth voltage sensor, the second inverter module is controlled. Based on the current flowing through the second current sensor, the current during the charging process of the second power battery is controlled and overcurrent faults are determined.

12. The traction converter as described in claim 1, characterized in that, Also includes: A phase sequence detection port is connected to the charging port and is used to measure the voltage phase sequence of the charging port.

13. The traction converter as described in claim 1, characterized in that, Also includes: A cooling system is provided for cooling the first auxiliary transformer module and the second auxiliary transformer module, the first inverter module and the second inverter module, the first transformer and the second transformer during power supply and charging.

14. The traction converter as described in claim 13, characterized in that, The cooling system includes: A water-circulating cooling system is used to cool the first inverter module and the second inverter module, the first auxiliary transformer module and the second auxiliary transformer module during power supply and charging. A wind-circulating cooling system is used to cool the first transformer and the second transformer during power supply and charging.

15. The traction converter as described in any one of claims 1 to 14, characterized in that, Also includes: The traction control unit is used to control the first auxiliary transformer module and the second auxiliary transformer module during the charging process of the first power battery and the second power battery, so that the harmonic components of the AC terminal of the first auxiliary transformer module cancel out the harmonic components of the AC terminal of the second auxiliary transformer module.

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