A high-speed train traction converter and a traction conversion control method

Abstract

The application provides a high-speed train traction converter and a traction conversion control method. The device comprises n multiple current conversion units, 2n pulse width controllers and combined switches. When the running speed of the high-speed train is in a first speed range, a first combined switch is closed and a second combined switch is opened. When the running speed of the high-speed train is in a second speed range, the second combined switch is closed and the first combined switch is opened. The three-phase switch tube states of the first three-level inverter and the second three-level inverter in all current conversion units are controlled according to the delay switch instruction to perform current conversion control. The second speed range is higher than the first speed range. Compared with the prior art, the technical scheme of the application can solve the technical problems in the prior art that the current device cannot simultaneously realize low-speed large current, medium-speed high voltage, continuous change of frequency from zero and the need to configure an additional filter device, resulting in a large volume.

Description

Technical Field

[0001] This invention relates to the field of high-speed magnetic levitation flying train technology, and in particular to a traction converter device and traction converter control method for a high-speed flying train. Background Technology

[0002] The high-speed maglev flying train (hereinafter referred to as the high-speed flying train) is a modern high-tech rail transportation tool. It achieves contactless levitation and guidance between the train and the track through electromagnetic force. It uses the electromagnetic force generated by the long stator linear motor to pull the flying train. Its speed can reach more than 1,000 km / h, and can even be developed to 4,000 km / h. It is a true ground-hugging flying vehicle.

[0003] The traction converter is used to provide the required variable frequency and voltage power to the long stator linear motor of the high-speed maglev train. During the low-speed start-up and low-speed operation phases of the high-speed maglev train, the linear motor has a low back EMF. At this time, the converter needs to provide a low-voltage, high-current output. The converter's output frequency synchronously increases from zero, and the high current provides the maglev train with a large thrust to maintain its continuous acceleration. During the high-speed medium-to-high-speed operation and cruising phases of the high-speed maglev train, the linear motor has a high back EMF, requiring the converter to output a higher voltage and a larger rated output frequency. Simultaneously, because the high-speed maglev train needs to overcome forward resistance, the traction converter needs to provide a relatively low cruising current to maintain its speed stability. Based on the requirements of high-speed maglev trains, the traction converter needs to meet the requirements of high starting current (high thrust), high cruising voltage (high motor back EMF), low harmonic distortion rate (low vehicle vibration), and continuous frequency variation from zero to rated operating conditions (wide speed range).

[0004] Currently, linear motor drives for high-speed flying trains generally use two-level or multi-level inverters. However, due to the voltage and current withstand limits of power devices, current traction converters cannot simultaneously meet the requirements of output voltage reaching 20 kilovolts or above, output current not less than 800 amperes, and output frequency continuously varying from zero to hundreds of hertz. Moreover, traditional inverters have the disadvantage of large output harmonics, requiring the addition of large filter devices at the output end to reduce output current harmonics, which occupies a large volume and space. Summary of the Invention

[0005] To address one of the problems existing in the prior art, the present invention provides a traction converter device and traction converter control method for high-speed flying trains.

[0006] According to one aspect of the present invention, a high-speed flying train traction converter is provided, the device comprising:

[0007] The n-level converter unit includes a first three-level inverter, a second three-level inverter, and a combined transformer. Both the first and second three-level inverters include three-phase switching transistors. In the nth-level converter unit, each phase level output of the first and second three-level inverters is connected to the primary side of the combined transformer in this unit, and the secondary side of the combined transformer in this unit is grounded. In the second to nth-level converter units, each phase level output of the first and second three-level inverters of two adjacent converter units is connected in series with open windings through the combined transformers in the current two units. The secondary side of the combined transformer in the nth-level converter unit is connected to a three-phase motor.

[0008] There are 2n pulse width controllers, which are connected one-to-one with the n first three-level inverters and n second three-level inverters in the n-fold converter unit. The pulse width controllers are used to generate delay switching commands.

[0009] A combination switch is disposed between the first converter unit and the second converter unit. The combination switch includes a first combination switch and a second combination switch. The first combination switch is used to connect and disconnect the secondary side of the inverter combination in the second converter unit from the primary side of the inverter combination in the first converter unit. The second combination switch is used to connect and disconnect the secondary side of the inverter combination in the second converter unit from the secondary side of the inverter combination in the first converter unit.

[0010] When the high-speed maglev train's operating speed is within the first speed range, the first combination switch is closed and the second combination switch is open. According to the delay switch command, the state of the three-phase switching transistors of the first three-level inverter and the second three-level inverter in all converter units is controlled to perform converter control. When the high-speed maglev train's operating speed is within the second speed range, the second combination switch is closed and the first combination switch is open. According to the delay switch command, the state of the three-phase switching transistors of the first three-level inverter and the second three-level inverter in all converter units is controlled to perform converter control. The second speed range is higher than the first speed range.

[0011] Furthermore, each pulse width controller includes a sine wave modulator, a triangular carrier generator, a waveform comparator, and a delay unit. The sine wave modulator is used to generate a sine wave, the triangular carrier generator is used to generate a triangular carrier, the waveform comparator is used to compare the ordinate values ​​of the sine wave and the triangular carrier at the same time to generate a status command, and the delay unit is used to generate a delay switch command based on the status command.

[0012] Furthermore, when the high-speed flying train is operating at a speed within the first speed range, the phase angle difference between the sine waves input to the first three-level inverter and the second three-level inverter in the first converter unit is 0°, the amplitude of the sine waves input to the first three-level inverter and the second three-level inverter in the second to nth converter units is 0, and the phase angle difference between the triangular carrier waves input to the first three-level inverter and the second three-level inverter in each converter unit is 180°.

[0013] Furthermore, when the high-speed flying train operates within the second speed range, the phase angle difference between the sine waves input to the first three-level inverter in each converter unit is 0°, the phase angle difference between the sine waves input to the second three-level inverter in each converter unit is 0°, and the phase angle difference between the sine waves input to the first three-level inverter and the sine waves input to the second three-level inverter in each converter unit is 180°. The phase angle difference of the triangular carrier of the device is 0°. When 1≤i≤(n+1) / 2, the initial value Y of the ordinate of the triangular carrier input to the i-th converter unit is Y=2*(i-1) / n. When Y≠0, it shows negative growth, and when Y=0, it shows positive growth. When (n+1) / 2<i≤n, the initial value Y' of the ordinate of the triangular carrier input to the i-th converter unit is Y'=2*(n-i+1) / n. When Y≠1, it shows positive growth, and when Y=1, it shows negative growth.

[0014] Furthermore, the status instructions include three types: N_State, O_State, and P_State. When the ordinate value of the sine wave is greater than 0 and greater than the ordinate value of the upper triangular carrier wave, the waveform comparator generates a P_State status instruction. When the ordinate value of the sine wave is greater than 0 and less than or equal to the ordinate value of the upper triangular carrier wave, the waveform comparator generates an O_State status instruction. When the ordinate value of the sine wave is less than or equal to 0 and greater than the ordinate value of the lower triangular carrier wave, the waveform comparator generates an O_State status instruction. When the ordinate value of the sine wave is less than or equal to 0 and less than or equal to the ordinate value of the lower triangular carrier wave, the waveform comparator generates an N_State status instruction.

[0015] Furthermore, the three-phase switching transistors include phase A, phase B, and phase C, and each phase switching transistor includes an upper outer transistor, an upper inner transistor, a lower inner transistor, and a lower outer transistor. The timer includes a three-phase timer, and each phase timer includes an upper outer transistor timer, an upper inner transistor timer, a lower inner transistor timer, and a lower outer transistor timer. When the state instruction is P_State and the upper outer transistor timer is 0, the delay switch instruction is: upper inner transistor on, lower inner transistor off, lower outer transistor off, lower inner transistor timer... The timer counts the preset delay duration and the upper external tube is turned on. When the state instruction is P_State and the upper external tube timer is not 0, the delay switch instruction is: upper inner tube turned on, lower inner tube turned off, lower external tube turned off, lower inner tube timer counts the preset delay duration, upper external tube turned off, and upper external tube timer counts down by 1. When the state instruction is O_State and both the upper and lower inner tube timers are 0, the delay switch instruction is: upper external tube turned off, lower external tube turned off, and upper external tube timer counts down by 1. The upper inner tube timer and the lower inner tube timer are both set to a preset delay duration. When the state instruction is O_State and both the upper and lower inner tube timers are not zero, the delay switch instruction is: upper outer tube off, lower outer tube off, upper outer tube timer set to the preset delay duration, lower outer tube timer set to the preset delay duration, upper inner tube off, upper inner tube timer decremented by 1, lower inner tube off and lower inner tube timer decremented. 1. When the status instruction is N_State and the lower outer tube timer is 0, the delay switch instruction is: upper outer tube off, upper inner tube off, lower inner tube on, upper inner tube timer set to the preset delay duration, and lower outer tube on. When the status instruction is N_State and the lower outer tube timer is not 0, the delay switch instruction is: upper outer tube off, upper inner tube off, lower inner tube on, upper inner tube timer set to the preset delay duration, lower outer tube off, and lower outer tube timer decremented by 1.

[0016] Furthermore, the sine wave includes an A-phase sine wave, a B-phase sine wave, and a C-phase sine wave. The amplitude range of the three phases of the sine wave is -1 to +1, and the phase angle difference between the A-phase sine wave and the B-phase sine wave is 120°, as is the phase angle difference between the B-phase sine wave and the C-phase sine wave. The triangular carrier includes an upper triangular carrier and a lower triangular carrier. The amplitude range of the upper triangular carrier is 0 to +1, and the amplitude range of the lower triangular carrier is -1 to 0. The upper and lower triangular carriers are in the same phase. The A-phase sine wave is used to control the on and off of the A-phase switch, the B-phase sine wave is used to control the on and off of the B-phase switch, and the C-phase sine wave is used to control the on and off of the C-phase switch.

[0017] According to another aspect of the present invention, a traction converter control method is provided, the method utilizing the traction converter device proposed above for converter control, the method comprising:

[0018] When the high-speed flying train is operating at a speed within the first speed range, the first combination switch is closed and the second combination switch is opened to connect the secondary side of the inverter combination in the second converter unit to the primary side of the inverter combination in the first converter unit. 2n pulse width controllers are used to generate delay switch commands corresponding one-to-one with the n first three-level inverters and n second three-level inverters in the n converter units. The delay switch commands are used to control the state of the three-phase switching transistors of the first three-level inverters and the second three-level inverters in all converter units for converter control.

[0019] When the high-speed train is operating at a speed within the second speed range, the second combination switch is closed and the first combination switch is opened to connect the secondary side of the inverter combination in the second converter unit to the secondary side of the inverter combination in the first converter unit. 2n pulse width controllers are used to generate delay switch commands corresponding one-to-one with the n first three-level inverters and n second three-level inverters in the n converter units. These delay switch commands are then used to control the state of the three-phase switching transistors of the first and second three-level inverters in all converter units for converter control. The second speed range is higher than the first speed range.

[0020] Furthermore, each pulse width controller includes a sinusoidal modulation wave generator, a triangular carrier generator, a waveform comparator, and a delay unit, which generate delay switching instructions in the following manner:

[0021] A sine wave is generated using a sine modulation wave generator;

[0022] A triangular carrier wave is generated using a triangular carrier wave generator;

[0023] A waveform comparator is used to compare the ordinate values ​​of a sine wave and a triangular carrier wave at the same moment to generate a status command.

[0024] A delay switch instruction is generated based on the status instruction using a delay timer.

[0025] Furthermore, when the high-speed flying train is operating at a speed within the first speed range, the phase angle difference between the sine waves input to the first three-level inverter and the second three-level inverter in the first converter unit is 0°, the amplitude of the sine waves input to the first three-level inverter and the second three-level inverter in the second to nth converter units is 0, and the phase angle difference between the triangular carrier waves input to the first three-level inverter and the second three-level inverter in each converter unit is 180°.

[0026] When the high-speed flying train operates at a speed within the second speed range, the phase angle difference between the sine waves input to the first three-level inverter in each converter unit is 0°, the phase angle difference between the sine waves input to the second three-level inverter in each converter unit is 0°, and the phase angle difference between the sine waves input to the first three-level inverter and the sine waves input to the second three-level inverter in each converter unit is 180°. The phase angle difference of the angular carrier is 0°. When 1≤i≤(n+1) / 2, the initial value Y of the ordinate of the triangular carrier input to the i-th converter unit is Y=2*(i-1) / n. When Y≠0, it shows negative growth, and when Y=0, it shows positive growth. When (n+1) / 2<i≤n, the initial value Y' of the ordinate of the triangular carrier input to the i-th converter unit is Y'=2*(n-i+1) / n. When Y≠0, it shows positive growth, and when Y=0, it shows negative growth.

[0027] The present invention provides a traction converter device and traction converter control method for a high-speed flying train. This device connects the phase level output of each of the first and second three-level inverters in the first converter unit to the primary side of the combined transformer in the same unit. Furthermore, it connects the phase level output of each of the first and second three-level inverters in the second to nth converter units in series with open windings via a combined inverter. Switching between the first and second combined switches enables switching between the inverter combinations in the second and first converter units. A pulse width controller generates delayed switching commands to control the state of the three-phase switches in each first and second three-level inverter, thus forming a multi-phase three-level full-bridge inverter topology. This structure is simple, small in size, and can meet the requirements of high-speed flying trains at different operating stages, including low-speed high current, medium-speed high voltage, continuous frequency variation from zero, and low ripple current. Attached Figure Description

[0028] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0029] Figure 1 A schematic diagram of the topology of a high-speed flying train traction converter according to a specific embodiment of the present invention is shown;

[0030] Figure 2A schematic diagram of a three-phase sinusoidal modulation wave according to a specific embodiment of the present invention is shown;

[0031] Figure 3 A schematic diagram of a triangular carrier wave provided according to a specific embodiment of the present invention is shown;

[0032] Figure 4 A schematic diagram of the state instruction generation process according to a specific embodiment of the present invention is shown;

[0033] Figure 5 A schematic diagram of a three-level inverter according to a specific embodiment of the present invention is shown;

[0034] Figure 6 A schematic diagram illustrating the working principle of a delay device according to a specific embodiment of the present invention is shown;

[0035] Figure 7 A schematic diagram of the sine wave and carrier wave input to the first three-level inverter in mode one of the first converter unit provided according to a specific embodiment of the present invention is shown;

[0036] Figure 8 A schematic diagram of the sine wave and carrier wave input to the second three-level inverter in mode one of the first converter unit provided according to a specific embodiment of the present invention is shown;

[0037] Figure 9 A schematic diagram of the total output waveform of the converter provided according to a specific embodiment of the present invention in mode one is shown;

[0038] Figure 10 A schematic diagram of the sine wave and carrier wave input to the first three-level inverter in mode two of a quadruple converter unit provided according to a specific embodiment of the present invention is shown;

[0039] Figure 11 A schematic diagram of the sine wave and carrier wave input to the second three-level inverter in mode two of a quadruple converter unit provided according to a specific embodiment of the present invention is shown;

[0040] Figure 12 A schematic diagram of the total output waveform of the converter provided according to a specific embodiment of the present invention in mode two is shown. Detailed Implementation

[0041] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. 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 a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. 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.

[0042] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0043] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0044] like Figure 1 As shown, a high-speed flying train traction converter is provided according to a specific embodiment of the present invention, the device comprising:

[0045] The n-level converter unit includes a first three-level inverter, a second three-level inverter, and a combined transformer. Both the first and second three-level inverters include three-phase switching transistors. In the first-level converter unit, each phase level output of the first and second three-level inverters is connected to the primary side of the combined transformer in this unit, and the secondary side of the combined transformer in this unit is grounded. In the second to nth-level converter units, each phase level output of the first and second three-level inverters of two adjacent converter units is connected in series with open windings through the combined transformers in the current two units. The secondary side of the combined transformer in the nth-level converter unit is connected to the three-phase motor.

[0046] There are 2n pulse width controllers, which are connected one-to-one with the n first three-level inverters and n second three-level inverters in the n-fold converter unit. The pulse width controllers are used to generate delay switching commands.

[0047] A combination switch is disposed between the first converter unit and the second converter unit. The combination switch includes a first combination switch and a second combination switch. The first combination switch is used to connect and disconnect the secondary side of the inverter combination in the second converter unit from the primary side of the inverter combination in the first converter unit. The second combination switch is used to connect and disconnect the secondary side of the inverter combination in the second converter unit from the secondary side of the inverter combination in the first converter unit.

[0048] When the high-speed maglev train's operating speed is within the first speed range, the first combination switch is closed and the second combination switch is open. According to the delay switch command, the state of the three-phase switching transistors of the first three-level inverter and the second three-level inverter in all converter units is controlled to perform converter control. When the high-speed maglev train's operating speed is within the second speed range, the second combination switch is closed and the first combination switch is open. According to the delay switch command, the state of the three-phase switching transistors of the first three-level inverter and the second three-level inverter in all converter units is controlled to perform converter control. The second speed range is higher than the first speed range.

[0049] In this invention, n is a positive integer, also known as a cascaded multiplication number; please refer to [reference needed]. Figure 1In this embodiment, the first three-level inverter iX and the second three-level inverter iY in each converter unit include three-phase level outputs: phase A level, phase B level, and phase C level. Correspondingly, each combined transformer includes phase A transformer TiA, phase B transformer TiB, and phase C transformer TiC, where i represents the i-th converter unit, and 1≤i≤n. Each phase transformer includes a primary side and a secondary side. The primary side includes three connection points, defined as P1, P2, and P3 from bottom to top, and the secondary side includes two connection points, defined as S1 and S2 from bottom to top. In any given converter unit, the A-phase output of the first three-level inverter iX is connected to point P3 of the A-phase transformer TiA in that converter unit; the A-phase output of the second three-level inverter iY is connected to point P1 of the A-phase transformer TiA; the B-phase output of the first three-level inverter iX is connected to point P3 of the B-phase transformer TiB; the B-phase output of the second three-level inverter iY is connected to point P1 of the B-phase transformer TiB; the C-phase output of the first three-level inverter iX is connected to point P3 of the C-phase transformer TiC; and the C-phase output of the second three-level inverter iY is connected to point P1 of the C-phase transformer TiC. Furthermore, the S1 voltage of the A-phase transformer T1A, B-phase transformer T1B, and C-phase transformer T1C in the first converter unit is connected to... Both the S2 and S3 connection points are grounded through grounding resistor R1. The S2 connection points of the A-phase transformer TnA, B-phase transformer TnB, and C-phase transformer TnC in the nth converter unit are connected to the A-phase, B-phase, and C-phase of the three-phase motor M, respectively. The S1 connection points are connected to the S2 connection points of the A-phase transformer Tn-1A, B-phase transformer Tn-1B, and C-phase transformer Tn-1C in the (n-1)th converter unit, respectively. The S1 connection points of the A-phase transformer Tn-1A, B-phase transformer Tn-1B, and C-phase transformer Tn-1C in the (n-1)th converter unit are connected to the S2 connection points of the A-phase transformer Tn-2A, B-phase transformer Tn-2B, and C-phase transformer Tn-2C in the (n-2)th converter unit, and so on, until the second converter unit.

[0050] Point S1 of the A-phase transformer T2A, B-phase transformer T2B, and C-phase transformer T2C in the second converter unit can be connected to point P2 of the same transformer in the first converter unit via the first combination switch S1'. Similarly, point S2 of the transformers in the first converter unit can be connected via the second combination switch S2'. When the first combination switch S1' is closed and the second combination switch S2' is open, the transformers function as current-sharing reactors, and the inverters in the second to nth converter units operate in soft bypass mode. Their leakage inductance can be used as filter inductors to optimize harmonics in the output current, thereby reducing current ripple. When the second combination switch S2' is closed and the first combination switch S1' is open, the transformers function as cascaded step-up transformers. To achieve automatic switching between the two combination switches, this invention may also include a mode control module to switch the combination switches according to the operating phase of the high-speed flying train.

[0051] This configuration provides a high-speed maglev train traction converter device. The device connects each phase output of the first and second three-level inverters in the first converter unit to the primary side of the combined transformer in this unit. Furthermore, it connects each phase output of the first to nth converter units via open windings in series through a combined inverter. Switching between the first and second combined switches allows for switching between the inverter combinations in the second and first converter units. A pulse width controller generates delayed switching commands to control the state of the three-phase switches in each first and second three-level inverter, thus forming a multi-phase three-level full-bridge inverter topology. This structure is simple, compact, and meets the requirements of high-speed maglev trains at different operating stages, including low-speed high current, medium-speed high voltage, continuous frequency variation from zero, and low ripple current. Compared with the prior art, the technical solution of the present invention can solve the technical problems in the prior art that the current device cannot simultaneously achieve low-speed large current, medium-speed high voltage, continuous frequency change from zero, and large size due to the need to configure additional filtering device.

[0052] The first speed range and the second speed range are relative concepts. The first speed range refers to a lower speed, and the second speed range refers to a higher speed. For example, the speed of the high-speed flying train during the start-up acceleration phase and the low-speed operation phase can be considered to belong to the first speed range, while the speed of the medium-to-high-speed operation phase and the cruise phase can be considered to belong to the second speed range. The specific range is determined according to the actual situation. As a specific embodiment of the present invention, the first speed range is defined as 0 to 100 km / h, corresponding to a frequency of 0 to 10 Hz, and the second speed range is defined as 100 to 1000 km / h, corresponding to a frequency of 10 to 100 Hz.

[0053] In this embodiment of the invention, each pulse width controller includes a sine wave modulator, a triangular carrier generator, a waveform comparator, and a delay unit. The sine wave modulator generates a sine wave, the triangular carrier generator generates a triangular carrier wave, the waveform comparator compares the ordinate values ​​of the sine wave and the triangular carrier wave at the same moment to generate a status command, and the delay unit generates a delay switch command based on the status command. Wherein, as... Figure 1 As shown, the sinusoidal modulation wave generator is also called the modulation wave module 1X~nX and 1Y~nY, the triangular carrier generator is also called the triangular carrier module 1X~nX and 1Y~nY, the waveform comparator is also called the comparison module 1X~nX and 1Y~nY, and the delay unit is also called the dead zone module 1X~nX and 1Y~nY.

[0054] Furthermore, since each inverter's three-phase switching transistors include phase A, phase B, and phase C switching transistors, in order to control the on / off state of each phase switching transistor, please refer to a specific embodiment of the present invention. Figure 2 and Figure 3 The sine wave includes phase A, phase B, and phase C. The amplitude range of the three phases is -1 to +1, and the phase angle difference between phase A and phase B is 120°, as is the phase angle difference between phase B and phase C. The triangular carrier includes an upper triangular carrier and a lower triangular carrier. The amplitude range of the upper triangular carrier is 0 to +1, and the amplitude range of the lower triangular carrier is -1 to 0. The upper and lower triangular carriers are in the same phase. The phase A sine wave is used to control the on and off of the phase A switch, the phase B sine wave is used to control the on and off of the phase B switch, and the phase C sine wave is used to control the on and off of the phase C switch.

[0055] In this embodiment of the invention, when the high-speed flying train is operating within a first speed range, the phase angle difference between the sine waves input to the first three-level inverter and the second three-level inverter in the first converter unit is 0°, the amplitude of the sine waves input to the first three-level inverter and the second three-level inverter in the second to nth converter units is 0, and the phase angle difference between the triangular carrier waves input to the first three-level inverter and the second three-level inverter in each converter unit is 180°. The sine waves input to the first three-level inverter and the second three-level inverter in the first converter unit each include a phase A sine wave, a phase B sine wave, and a phase C sine wave. A phase angle difference of 0° means that the phase angle difference between the corresponding phase sine waves is 0°. The statement that the phase angle difference of the triangular carriers of the first three-level inverter and the second three-level inverter in each input converter unit is 180° means that in any converter unit, the phase angle difference of the upper triangular carriers of the first three-level inverter and the second three-level inverter is 180°, and the phase angle difference of the lower triangular carriers of the first three-level inverter and the second three-level inverter is also 180°.

[0056] In this embodiment of the invention, when the high-speed flying train's operating speed is within the second speed range, the phase angle difference between the sine waves input to the first three-level inverter in each converter unit is 0°, the phase angle difference between the sine waves input to the second three-level inverter in each converter unit is 0°, and the phase angle difference between the sine waves input to the first three-level inverter and the sine waves input to the second three-level inverter in each converter unit is 180°. The phase angle difference of the triangular carrier of the converter is 0°. When 1≤i≤(n+1) / 2, the initial value Y of the ordinate of the triangular carrier input to the i-th converter unit is Y=2*(i-1) / n. When Y≠0, it shows negative growth, and when Y=0, it shows positive growth. When (n+1) / 2<i≤n, the initial value Y' of the ordinate of the triangular carrier input to the i-th converter unit is Y'=2*(n-i+1) / n. When Y≠1, it shows positive growth, and when Y=1, it shows negative growth.

[0057] In the above embodiments, a phase angle difference of 0° for the sine waves input to the first three-level inverter in each converter unit means that the phases of the sine waves input to the first three-level inverter in each converter unit are the same. Similarly, a phase angle difference of 0° for the sine waves input to the second three-level inverter in each converter unit means that the phases of the sine waves input to the second three-level inverter in each converter unit are also the same. A phase angle difference of 0° for the triangular carrier waves input to the first and second three-level inverters in each converter unit means that the upper triangular carrier waves of the two inverters in each converter unit have the same phase, and the lower triangular carrier waves also have the same phase. Taking a quadrupled converter unit as an example, when n=4, assuming the initial value of the horizontal coordinate of the triangular carrier is 0, the following results can be obtained according to the above formula for calculating the initial value of the vertical coordinate and the growth method:

[0058] The triangular carrier in the i=1th recurrent converter unit: the initial coordinate value is (0,0), since And Y = 0, therefore the growth direction is positive;

[0059] The triangular carrier in the i=2nd converter unit has initial coordinates of (0, 1 / 2). And Y≠0, therefore the growth direction is negative;

[0060] The triangular carrier in the i=3rd converter unit: the initial coordinates are (0,1), because... And Y = 1, therefore the growth direction is negative;

[0061] The triangular carrier in the i=4th converter unit has an initial coordinate value of (0, 1 / 2). And Y≠1, therefore the growth direction is positive.

[0062] Further, please refer to Figure 4 In this embodiment, the status instructions include three types: N_State, O_State, and P_State. When the ordinate value of the sine wave is greater than 0 and greater than the ordinate value of the upper triangular carrier wave, the waveform comparator generates a P_State status instruction. When the ordinate value of the sine wave is greater than 0 and less than or equal to the ordinate value of the upper triangular carrier wave, the waveform comparator generates an O_State status instruction. When the ordinate value of the sine wave is less than or equal to 0 and greater than the ordinate value of the lower triangular carrier wave, the waveform comparator generates an O_State status instruction. When the ordinate value of the sine wave is less than or equal to 0 and less than or equal to the ordinate value of the lower triangular carrier wave, the waveform comparator generates an N_State status instruction.

[0063] Please refer to Figure 5 and Figure 6In this embodiment, the three-phase switching transistors include phase A switching transistor An, phase B switching transistor Bn, and phase C switching transistor Cn, and each phase switching transistor includes an upper outer transistor, an upper inner transistor, a lower inner transistor, and a lower outer transistor. The delay circuit includes a three-phase delay circuit, and each phase delay circuit includes an upper outer transistor timer, an upper inner transistor timer, a lower inner transistor timer, and a lower outer transistor timer. When the state instruction is P_State and the upper outer transistor timer is 0, the delay switch instruction is upper inner transistor on, lower inner transistor off, lower outer transistor off, and so on. The lower inner tube timer counts for a preset delay duration and the upper outer tube is turned on. When the status instruction is P_State and the upper outer tube timer is not 0, the delay switch instructions are: upper inner tube turned on, lower inner tube turned off, lower outer tube turned off, lower inner tube timer counts for the preset delay duration, upper outer tube turned off, and upper outer tube timer counts down by 1. When the status instruction is O_State and both the upper and lower inner tube timers are 0, the delay switch instructions are: upper outer tube turned off, lower outer tube turned off. The upper outer tube timer and lower outer tube timer are set to a preset delay duration. The upper inner tube is turned on, and the lower inner tube is turned on. When the state instruction is O_State and both the upper and lower inner tube timers are not zero, the delay switch instruction is: upper outer tube off, lower outer tube off, upper outer tube timer set to the preset delay duration, lower outer tube timer set to the preset delay duration, upper inner tube off, upper inner tube timer decremented by 1, lower inner tube off, and the lower inner tube timer is turned on. The delay switch command is as follows: When the status instruction is N_State and the lower outer tube timer is 0, the delay switch command is: upper outer tube off, upper inner tube off, lower inner tube on, upper inner tube timer set to the preset delay duration, and lower outer tube on. When the status instruction is N_State and the lower outer tube timer is not 0, the delay switch command is: upper outer tube off, upper inner tube off, lower inner tube on, upper inner tube timer set to the preset delay duration, lower outer tube off, and lower outer tube timer decremented by 1.

[0064] Specifically, such as Figure 5 As shown, in the nth converter unit, Qn1, Qn5, and Qn9 are the upper outer tubes of phase A switch An, phase B switch Bn, and phase C switch Cn, respectively; Qn2, Qn6, and Qn10 are the upper inner tubes of phase A switch An, phase B switch Bn, and phase C switch Cn, respectively; Qn3, Qn7, and Qn11 are the lower inner tubes of phase A switch An, phase B switch Bn, and phase C switch Cn, respectively; and Qn4, Qn8, and Qn12 are the lower outer tubes of phase A switch An, phase B switch Bn, and phase C switch Cn, respectively. The upper outer tubes and lower inner tubes are complementary, and the upper inner tubes and lower outer tubes are also complementary. Please refer to [reference needed]. Figure 6This example demonstrates the delay control of the A-phase switching transistors in the first-stage converter unit. Q1, Q2, Q3, and Q4 represent the upper outer transistor, upper inner transistor, lower inner transistor, and lower outer transistor, respectively; 0 indicates off, and 1 indicates on. Cnt_Q1, Cnt_Q2, Cnt_Q3, and Cnt_Q4 represent the upper outer transistor timer, upper inner transistor timer, lower inner transistor timer, and lower outer transistor timer, respectively. DeadTime represents the preset delay duration, used to control the delay turn-on time of the complementary transistor. The program execution time is set to SysPe. Given the following parameters: riod, the maximum turn-off delay time of the power device is Tdoff, the minimum turn-on delay time is Tdon, the minimum rise time is Tr, the maximum fall time is Tf, the minimum turn-on delay time of the driver circuit is Tddvon, and the maximum turn-off delay time is Tddvoff, then DeadTime ≥ [(Tdoff+Tf)-(Tdon+Tr)+(Tddvoff-Tddvon)]*1.5 / SysPeriod. This method converts the state command from the waveform comparator into the specific switching action of the switching transistor and controls the complementary transistor to turn on with a delay, thereby avoiding bridge arm shoot-through problems caused by switching speed.

[0065] Based on the above embodiments, when the converter is in Mode 1 (current sharing reactor mode), that is, when each sinusoidal modulation wave generator and triangular carrier generator generates the corresponding sinusoidal wave and triangular carrier according to the requirements of the aforementioned first speed range, the first combination switch S1' is closed and connected, and the second combination switch S2' is open. The converter provides low-speed, high-current. This mode is suitable for operation in the frequency range of 0Hz to 10Hz. When the converter is in Mode 2 (open-winding transformer cascade mode), that is, when each sinusoidal modulation wave generator and triangular carrier generator generates the corresponding sinusoidal wave and triangular carrier according to the requirements of the aforementioned second speed range, the second combination switch S2' is closed and connected, and the first combination switch S1' is open. The converter provides cruising high voltage. This mode is suitable for operation in the frequency range of 10Hz to 100Hz. By switching between Mode 1 and Mode 2, the output frequency of the traction converter can be continuously varied from 0 to 100Hz, propelling the high-speed flying train from a standstill to a continuous change in cruising speed. Furthermore, Mode 1, through carrier phase inversion modulation technology, reduces the output voltage harmonics of the traction converter in the low-speed range by 10.53% compared to traditional converters, achieving low output voltage harmonics in the low-frequency range. It also utilizes the leakage inductance of the cascaded output transformer to enhance the continuity of the traction converter's output current, reducing the output filter inductance and achieving low-speed, high-current output capability. This eliminates the need for external filtering equipment, helping to reduce the cost and size / weight of the traction converter, and also contributing to smoother operation of the long stator linear motor of the high-speed flying train. Mode 2, through modulation wave phase inversion + carrier phase shift + cascaded multiplexing modulation technology, effectively increases the total output voltage of the converter, achieving high speed and high voltage, and significantly reducing the harmonic distortion rate of the output voltage compared to traditional cascaded converters (e.g., a 12.58% reduction with a quadruple converter unit). The organic combination of Modes 1 and 2 not only increases the total output capacity of the traction converter but also effectively reduces the output voltage and current harmonics of the traction converter system, meeting the power supply requirements of low-speed, high-current, high-speed, high-voltage, and low-ripple current for high-speed flying trains.

[0066] According to another aspect of the present invention, a traction converter control method is provided, the method utilizing the traction converter device proposed above for converter control, the method comprising:

[0067] When the high-speed flying train is operating at a speed within the first speed range, the first combination switch is closed and the second combination switch is opened to connect the secondary side of the inverter combination in the second converter unit to the primary side of the inverter combination in the first converter unit. 2n pulse width controllers are used to generate delay switch commands corresponding one-to-one with the n first three-level inverters and n second three-level inverters in the n converter units. The delay switch commands are used to control the state of the three-phase switching transistors of the first three-level inverters and the second three-level inverters in all converter units for converter control.

[0068] When the high-speed train is operating at a speed within the second speed range, the second combination switch is closed and the first combination switch is opened to connect the secondary side of the inverter combination in the second converter unit to the secondary side of the inverter combination in the first converter unit. 2n pulse width controllers are used to generate delay switch commands corresponding one-to-one with the n first three-level inverters and n second three-level inverters in the n converter units. These delay switch commands are then used to control the state of the three-phase switching transistors of the first and second three-level inverters in all converter units for converter control. The second speed range is higher than the first speed range.

[0069] Furthermore, each pulse width controller includes a sinusoidal modulation wave generator, a triangular carrier generator, a waveform comparator, and a delay unit, which generate delay switching instructions in the following manner:

[0070] A sine wave is generated using a sine modulation wave generator;

[0071] A triangular carrier wave is generated using a triangular carrier wave generator;

[0072] A waveform comparator is used to compare the ordinate values ​​of a sine wave and a triangular carrier wave at the same moment to generate a status command.

[0073] A delay switch instruction is generated based on the status instruction using a delay timer.

[0074] Furthermore, when the high-speed flying train is operating at a speed within the first speed range, the phase angle difference between the sine waves input to the first three-level inverter and the second three-level inverter in the first converter unit is 0°, the amplitude of the sine waves input to the first three-level inverter and the second three-level inverter in the second to nth converter units is 0, and the phase angle difference between the triangular carrier waves input to the first three-level inverter and the second three-level inverter in each converter unit is 180°.

[0075] When the high-speed flying train operates at a speed within the second speed range, the phase angle difference between the sine waves input to the first three-level inverter in each converter unit is 0°, the phase angle difference between the sine waves input to the second three-level inverter in each converter unit is 0°, and the phase angle difference between the sine waves input to the first three-level inverter and the sine waves input to the second three-level inverter in each converter unit is 180°. The phase angle difference of the angular carrier is 0°. When 1≤i≤(n+1) / 2, the initial value Y of the ordinate of the triangular carrier input to the i-th converter unit is Y=2*(i-1) / n. When Y≠0, it shows negative growth, and when Y=0, it shows positive growth. When (n+1) / 2<i≤n, the initial value Y' of the ordinate of the triangular carrier input to the i-th converter unit is Y'=2*(n-i+1) / n. When Y≠0, it shows positive growth, and when Y=0, it shows negative growth.

[0076] The relevant examples of the traction converter control method in this invention can be referred to the aforementioned examples of the traction converter device, and will not be repeated here. In this way, a traction converter control method is provided. By switching between mode one and mode two, the cascaded mode of the first converter unit and the second converter unit can be switched. It can provide low-speed high current when the high-speed flying train is in the first speed range, and provide high voltage when its speed is in the second speed range. The frequency changes continuously from zero. At the same time, it can provide low ripple current without additional filtering devices, reducing the size and weight of the converter device.

[0077] To better understand the converter control method proposed in this invention, the following is combined with... Figures 7 to 12 The control flow will be further illustrated with a specific embodiment. The turns ratio of all transformers in the converter is set to k (primary:secondary), the DC bus voltage is ±V_BUS, the operating frequency of the delta carrier wave is f, and the average switching frequency of all switching transistors is equal to the frequency f of the delta carrier wave.

[0078] like Figure 7 , Figure 8 and Figure 9As shown, when the high-speed flying train is operating at a speed within the first speed range, the converter is in mode one, the first combination switch S1' is closed, the second combination switch S2' is open, and the three-level inverters 1X and 1Y are in inverter output mode. The phase of the A-phase sinusoidal modulation wave of inverter 1X is 0° (the phase angle difference between the B-phase sinusoidal modulation wave and the A-phase sinusoidal modulation wave is 120°, and the phase angle difference between the C-phase sinusoidal modulation wave and the B-phase sinusoidal modulation wave is 120°). The phase of the A-phase modulation wave of inverter 1Y is 0° (the phase angle difference between the B-phase sinusoidal modulation wave and the A-phase sinusoidal modulation wave is 120°, and the phase angle difference between the C-phase sinusoidal modulation wave and the B-phase sinusoidal modulation wave is 120°). The phase of the upper triangular carrier wave of inverter 1X is 0° (the phase angle difference between the lower triangular carrier wave and the upper triangular carrier wave is 0°). The phase of the upper triangular carrier wave of inverter 1Y is 180° (the phase of the lower triangular carrier wave is the same as that of the upper triangular carrier wave), meaning the first inverter is in the carrier phase-shifted open winding inverter mode. The amplitude of the three-phase sinusoidal modulation waves in inverters 2X~nX and 2Y~nY is 0. After processing by the comparison module and dead-zone module, the upper and lower inner tubes of phase A, phase B, and phase C will automatically remain on, while the remaining outer tubes (phase A, phase B, and phase C) will remain off. This means the inverters in the second to nth converter units are in soft bypass mode. The formula for calculating the effective value of the total output line voltage of the converter in this mode is: Where V_BUS represents the DC bus voltage, k represents the transformer turns ratio, i.e. the primary side to the secondary side. The harmonic distortion rate of the voltage is 24.61%, which is 10.53% lower than the harmonic distortion rate of 35.14% of the output voltage of the traditional carrier non-phase shifted output voltage.

[0079] like Figure 10 , Figure 11 and Figure 12As shown, when the high-speed flying train is operating at its first speed range, the converter is in mode two, the first combination switch S1' is open, the second combination switch S2' is closed, and the three-level inverters 1X~nX and 1Y~nY are in inverter output mode. The phase of the A-phase sinusoidal modulation wave of inverters 1X~nX is 0° (the phase angle difference between the B-phase sinusoidal modulation wave and the A-phase sinusoidal modulation wave is 120°, and the phase angle difference between the C-phase sinusoidal modulation wave and the B-phase sinusoidal modulation wave is 120°). The phase of the A-phase sinusoidal modulation wave of inverters 1Y~nY is 180° (the phase angle difference between the B-phase sinusoidal modulation wave and the A-phase sinusoidal modulation wave is 120°, and the phase angle difference between the C-phase sinusoidal modulation wave and the B-phase sinusoidal modulation wave is 120°). The phase angle difference of the waves is 120°. Each triangular carrier wave of inverter 1X and inverter 1Y, inverter 2X and inverter 2Y, and inverter nX and inverter nY is in phase with each other, but the phases of each triangular carrier wave are staggered. That is, the initial abscissa of the i-th triangular carrier wave (1≤i≤(n+1) / 2) is 0, and the corresponding initial ordinate is 2*(i-1) / n, with a negative growth direction (automatically reversed when the calculated ordinate value is 0); the initial abscissa of the i-th triangular carrier wave ((n+1) / 2<i≤n) is 0, and the corresponding initial ordinate is 2*(n-i+1) / n, with a positive growth direction (automatically reversed when the calculated ordinate value is 1). In this mode, the formula for calculating the effective value of the line voltage of the total output of the converter is: Taking the quadruple converter unit as an example, the harmonic distortion rate of the total output line voltage of the converter device is 11.73%, which is 12.58% lower than the harmonic distortion rate of 24.31% of the output voltage of the traditional carrier without phase shift.

[0080] In summary, this invention provides a traction converter device and traction converter control method for high-speed flying trains. The device connects the phase level output of each of the first and second three-level inverters in the first converter unit to the primary side of the combined transformer in this unit. Furthermore, it connects the phase level output of each of the first and second three-level inverters in the second to nth converter units in series with open windings via a combined inverter. Switching between the first and second combined switches enables switching between two connection methods: the inverter combination in the second converter unit and the inverter combination in the first converter unit. A pulse width controller generates delayed switching commands to control the state of the three-phase switches in each first and second three-level inverter, thus forming a multi-phase three-level full-bridge inverter topology. This structure is simple, small in size, and can meet the requirements of high-speed flying trains at different operating stages, including low-speed high current, medium-speed high voltage, continuous frequency variation from zero, and low ripple current. Compared with the prior art, the technical solution of the present invention can solve the technical problems in the prior art that the current device cannot simultaneously achieve low-speed large current, medium-speed high voltage, continuous frequency change from zero, and large size due to the need to configure additional filtering device.

[0081] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0082] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0083] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0084] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A traction converter for a high-speed flying train, characterized in that, The device comprises: n multiple variable current units, each multiple variable current unit comprising a first three-level inverter, a second three-level inverter and a combined transformer, the first three-level inverter and the second three-level inverter each comprising three-phase switching tubes, the first three-level inverter and the second three-level inverter in each multiple variable current unit each comprising A-phase, B-phase and C-phase three-phase level outputs, each combined transformer comprising A-phase, B-phase and C-phase transformers, each A-phase transformer, each B-phase transformer and each C-phase transformer comprising a primary side and a secondary side; the primary side of the A-phase transformer, the B-phase transformer and the C-phase transformer in the first multiple variable current unit each comprising a P1 connection point, a P2 connection point and a P3 connection point arranged in sequence from bottom to top, the primary side of the A-phase transformer, the B-phase transformer and the C-phase transformer in the 2nd to nth multiple variable current units each comprising a P1 connection point and a P3 connection point arranged in sequence from bottom to top, and the secondary side of the A-phase transformer, the B-phase transformer and the C-phase transformer in each multiple variable current unit each comprising a S1 connection point and a S2 connection point arranged in sequence from bottom to top; in each multiple variable current unit, the A-phase level output of the first three-level inverter is connected to the P3 connection point of the A-phase transformer, the A-phase level output of the second three-level inverter is connected to the P1 connection point of the A-phase transformer, the B-phase level output of the first three-level inverter is connected to the P3 connection point of the B-phase transformer, the B-phase level output of the second three-level inverter is connected to the P1 connection point of the B-phase transformer, the C-phase level output of the first three-level inverter is connected to the P3 connection point of the C-phase transformer, the C-phase level output of the second three-level inverter is connected to the P1 connection point of the C-phase transformer, and the S1 connection points of the A-phase transformer, the B-phase transformer and the C-phase transformer in the first multiple variable current unit are grounded through a grounding resistor R1; the S2 connection points of the A-phase transformer, the B-phase transformer and the C-phase transformer in the nth multiple variable current unit are connected to the A-phase, the B-phase and the C-phase of a three-phase motor respectively, the S1 connection points of the A-phase transformer, the B-phase transformer and the C-phase transformer in the nth multiple variable current unit are connected to the S2 connection points of the A-phase transformer, the B-phase transformer and the C-phase transformer in the (n-1)th multiple variable current unit respectively, and the S1 connection points of the A-phase transformer, the B-phase transformer and the C-phase transformer in the (n-1)th multiple variable current unit are connected to the S2 connection points of the A-phase transformer, the B-phase transformer and the C-phase transformer in the (n-2)th multiple variable current unit, and so on, until the 2nd multiple variable current unit; 2n pulse width controllers, the 2n pulse width controllers being connected to the n first three-level inverters and the n second three-level inverters in the n multiple variable current units one by one, and the pulse width controllers being used to generate delay switch instructions; A combination switch is arranged between the first and second heavy current conversion units, the combination switch comprises a first combination switch and a second combination switch, S1 points of A-phase, B-phase and C-phase transformers of the second heavy current conversion unit are connected with P2 connection points of A-phase, B-phase and C-phase transformers of the first heavy current conversion unit through the first combination switch, and are connected with S2 connection points of A-phase, B-phase and C-phase transformers of the first heavy current conversion unit through the second combination switch, the first combination switch is used for connecting and disconnecting a secondary side of a combination transformer in the second heavy current conversion unit with a primary side of a combination transformer in the first heavy current conversion unit, and the second combination switch is used for connecting and disconnecting the secondary side of the combination transformer in the second heavy current conversion unit with a secondary side of the combination transformer in the first heavy current conversion unit; When the running speed of the high-speed flying train is in a first speed range, the first combination switch is closed, the second combination switch is opened, and the three-phase switch tube states of the first and second three-level inverters in all the heavy current conversion units are controlled according to the delay switch instruction to perform current conversion control, when the running speed of the high-speed flying train is in a second speed range, the second combination switch is closed, the first combination switch is opened, and the three-phase switch tube states of the first and second three-level inverters in all the heavy current conversion units are controlled according to the delay switch instruction to perform current conversion control, wherein the second speed range is higher than the first speed range; Each pulse width controller comprises a sine modulation wave generator, a triangular carrier wave generator, a waveform comparator and a delay timer, the sine modulation wave generator is used for generating a sine wave, the triangular carrier wave generator is used for generating a triangular carrier wave, the waveform comparator is used for comparing the vertical coordinate values of the sine wave and the triangular carrier wave at the same time to generate a state instruction, and the delay timer is used for generating the delay switch instruction according to the state instruction; When the running speed of the high-speed flying train is in a first speed range, the phase angle difference of the sine waves input to the first and second three-level inverters in the first heavy current conversion unit is 0°, the amplitude of the sine waves input to the first and second three-level inverters in the second to nth heavy current conversion units is 0, and the phase angle difference of the triangular carrier waves input to the first and second three-level inverters in each heavy current conversion unit is 180°.

2. The apparatus of claim 1, wherein, When the running speed of the high-speed train is in the second speed range, the phase angle difference of the sine wave input to the first three-level inverter in each multiple-conversion unit is 0°, the phase angle difference of the sine wave input to the second three-level inverter in each multiple-conversion unit is 0°, the phase angle difference of the sine wave input to the first three-level inverter and the sine wave input to the second three-level inverter in each multiple-conversion unit is 180°, the phase angle difference of the triangular carrier input to the first three-level inverter and the triangular carrier input to the second three-level inverter in each multiple-conversion unit is 0°, when the longitudinal coordinate initial value of the triangular carrier input to the i-th multiple-conversion unit is , and when it is in negative growth, when it is in positive growth, when the longitudinal coordinate initial value of the triangular carrier input to the i-th multiple-conversion unit is , and when it is in positive growth, when it is in negative growth.​​ 3. The apparatus of claim 2, wherein, The state instruction includes three state instructions of N State, O State and P State, when the longitudinal coordinate value of the sine wave is greater than 0 and greater than the longitudinal coordinate value of the upper triangular carrier, the waveform comparator generates the P State state instruction, when the longitudinal coordinate value of the sine wave is greater than 0 and less than or equal to the longitudinal coordinate value of the upper triangular carrier, the waveform comparator generates the O State state instruction, when the longitudinal coordinate value of the sine wave is less than or equal to 0 and greater than the longitudinal coordinate value of the lower triangular carrier, the waveform comparator generates the O State state instruction, and when the longitudinal coordinate value of the sine wave is less than or equal to 0 and less than or equal to the longitudinal coordinate value of the lower triangular carrier, the waveform comparator generates the N State state instruction.

4. The apparatus of claim 3, wherein, The three-phase switch tube includes A-phase switch tube, B-phase switch tube and C-phase switch tube, and each phase switch tube includes upper outer tube, upper inner tube, lower inner tube and lower outer tube, the delay timer includes three-phase delay timer, and each phase delay timer includes upper outer tube timer, upper inner tube timer, lower inner tube timer and lower outer tube timer, when the state instruction is P State and the upper outer tube timer is timing 0, the delay switch instruction is upper inner tube on, lower inner tube off, lower outer tube off, lower inner tube timer timing preset delay time length and upper outer tube on, when the state instruction is P State and the upper outer tube timer is not timing 0, the delay switch instruction is upper inner tube on, lower inner tube off, lower outer tube off, lower inner tube timer timing preset delay time length, upper outer tube off and upper outer tube timer timing reduction 1, when the state instruction is O State and the timing of the upper inner tube timer and the lower inner tube timer is 0, the delay switch instruction is upper outer tube off, lower outer tube off, upper outer tube timer timing preset delay time length, lower outer tube timer timing preset delay time length, upper inner tube on and lower inner tube on, when the state instruction is O State and the timing of the upper inner tube timer and the lower inner tube timer is not 0, the delay switch instruction is upper outer tube off, lower outer tube off, upper outer tube timer timing preset delay time length, lower outer tube timer timing preset delay time length, upper inner tube off, upper inner tube timer timing reduction 1, lower inner tube off and lower inner tube timer timing reduction 1, when the state instruction is N State and the lower outer tube timer is timing 0, the delay switch instruction is upper outer tube off, upper inner tube off, lower inner tube on, upper inner tube timer timing preset delay time length and lower outer tube on, when the state instruction is N State and the lower outer tube timer is not timing 0, the delay switch instruction is upper outer tube off, upper inner tube off, lower inner tube on, upper inner tube timer timing preset delay time length, lower outer tube off and lower outer tube timer timing reduction 1.

5. The apparatus of claim 4, wherein, The sine wave includes an A-phase sine wave, a B-phase sine wave and a C-phase sine wave, the amplitude of the sine wave of the three phases ranges from -1 to +1, the phase angle difference between the A-phase sine wave and the B-phase sine wave is 120°, the phase angle difference between the B-phase sine wave and the C-phase sine wave is 120°, the triangular carrier includes an upper triangular carrier and a lower triangular carrier, the amplitude of the upper triangular carrier ranges from 0 to +1, the amplitude of the lower triangular carrier ranges from -1 to 0, and the phase of the upper triangular carrier is the same as that of the lower triangular carrier, the A-phase sine wave is used to control the turn-on and turn-off of the A-phase switch tube, the B-phase sine wave is used to control the turn-on and turn-off of the B-phase switch tube, and the C-phase sine wave is used to control the turn-on and turn-off of the C-phase switch tube.

6. A traction converter control method for performing a conversion control using the traction converter device according to any one of claims 1 to 5, characterized by, The method comprises: When the running speed of the high-speed flying train is in a first speed range, a first combination switch is closed and a second combination switch is opened to connect the secondary side of the combination transformer in the second heavy current conversion unit with the primary side of the combination transformer in the first heavy current conversion unit, 2n pulse width controllers are used to generate delay switch instructions corresponding to n first three-level inverters and n second three-level inverters in n heavy current conversion units respectively, and the delay switch instructions are used to control the three-phase switch tube states of the first three-level inverters and the second three-level inverters in all the heavy current conversion units to perform current conversion control; When the running speed of the high-speed flying train is in a second speed range, the second combination switch is closed and the first combination switch is opened to connect the secondary side of the combination transformer in the second heavy current conversion unit with the secondary side of the combination transformer in the first heavy current conversion unit, 2n pulse width controllers are used to generate delay switch instructions corresponding to n first three-level inverters and n second three-level inverters in n heavy current conversion units respectively, and the delay switch instructions are used to control the three-phase switch tube states of the first three-level inverters and the second three-level inverters in all the heavy current conversion units to perform current conversion control, wherein the second speed range is higher than the first speed range.

7. The method of claim 6, wherein, Each of the pulse width controllers comprises a sine modulation wave generator, a triangular carrier generator, a waveform comparator and a delay timer, and the delay switch instruction is generated in the following manner: The sine modulation wave generator is used to generate a sine wave; The triangular carrier generator is used to generate a triangular carrier; The waveform comparator is used to compare the vertical coordinate values of the sine wave and the triangular carrier at the same time to generate a state instruction; The delay timer is used to generate the delay switch instruction according to the state instruction.

8. The method of claim 7, wherein, When the running speed of the high-speed flying train is in a first speed range, the phase angle difference of the sine wave input to the first three-level inverters and the second three-level inverters in the first heavy current conversion unit is 0°, the amplitude of the sine wave input to the first three-level inverters and the second three-level inverters in the 2nd to nth heavy current conversion units is 0, and the phase angle difference of the triangular carrier input to the first three-level inverters and the second three-level inverters in each heavy current conversion unit is 180°. When the running speed of the high-speed train is in the second speed range, the phase angle difference of the sine wave input to the first three-level inverter in each multiple-conversion unit is 0°, the phase angle difference of the sine wave input to the second three-level inverter in each multiple-conversion unit is 0°, the phase angle difference of the sine wave input to the first three-level inverter and the sine wave input to the second three-level inverter in each multiple-conversion unit is 180°, the phase angle difference of the triangular carrier input to the first three-level inverter and the triangular carrier input to the second three-level inverter in each multiple-conversion unit is 0°, when the ordinate of the triangular carrier input to the i-th multiple-conversion unit initially is , and when , it is in negative growth, when , it is in positive growth, when the ordinate of the triangular carrier input to the i-th multiple-conversion unit initially is , and when , it is in positive growth, when , it is in negative growth.

Images