A train, an AC drive system and a method, apparatus and medium for voltage control of a DC link therein

Abstract

The application discloses a train, an alternating-current transmission system, a voltage control method and device of an intermediate direct-current bus and a medium. The train alternating-current transmission system comprises a main generator, a rectification module, an intermediate direct-current bus and a braking resistor. The control method comprises the following steps: obtaining a reference voltage value of the intermediate direct-current bus, an actual voltage value of the intermediate direct-current bus and a current state of an electric brake handle; determining a braking chopper duty cycle at a current moment and a braking chopper duty cycle at a previous moment based on a PI control algorithm according to the reference voltage value of the intermediate direct-current bus and the actual voltage value of the intermediate direct-current bus; determining an output braking chopper duty cycle according to the braking chopper duty cycle at the current moment, the braking chopper duty cycle at the previous moment, the actual voltage value of the intermediate direct-current bus and the current state of the electric brake handle; and controlling the braking resistor to discharge at the output braking chopper duty cycle. The scheme can avoid voltage fluctuation of the intermediate direct-current bus and improve train operation stability and passenger comfort.

Description

Technical Field

[0001] This invention relates to the field of diesel locomotive technology, and in particular to a voltage control method, device and medium for a train, an AC drive system and its intermediate DC bus. Background Technology

[0002] In AC-drive diesel locomotives operating under electric power, the traction motor converts kinetic energy into electrical energy. The generated three-phase AC power is then converted into DC power and fed back to the intermediate DC bus to power the locomotive's equipment. The remaining electrical energy is dissipated in the braking resistor through brake chopper control. In existing technology, the voltage reference value and actual voltage value of the intermediate DC bus are typically calculated using a PI converter. The output value of the PI calculation is then directly used as the duty cycle of the brake chopper PWM output to control the discharge of the braking resistor, thereby keeping the voltage value of the intermediate DC bus within a reasonable range.

[0003] However, when the train experiences electric braking or rapid fluctuations in power consumption of the auxiliary converter module and train power supply module, the intermediate DC bus voltage will fluctuate. Due to the computational cycle of the network control system, PI calculations have a brief lag. When the peak value of the intermediate DC bus voltage is large or small, or when there are large oscillations, it can easily lead to failure of the auxiliary converter module and train power supply module, causing the train to unload. For a short period of time, the train cannot enter normal traction or electric braking conditions, affecting the normal operation of the train power supply equipment, and thus impacting driving safety and passenger comfort. Summary of the Invention

[0004] This invention provides a voltage control method, device, and medium for a train, an AC drive system, and its intermediate DC bus, which can avoid overvoltage, undervoltage, and abnormal fluctuations in the intermediate DC bus voltage, thereby improving the stability of the train's AC drive system and enhancing the stability of train operation and passenger comfort.

[0005] In a first aspect, the present invention provides a voltage control method for an intermediate DC bus, applied to a train AC drive system, the train AC drive system comprising: a main generator, a rectifier module, an intermediate DC bus, and a braking resistor; the three-phase AC output terminal of the main generator is electrically connected to the AC input terminal of the rectifier module, and the DC output terminal of the rectifier module is electrically connected to the intermediate DC bus; the braking resistor is electrically connected between the positive and negative terminals of the intermediate DC bus; the voltage control method for the intermediate DC bus comprises: Obtain the reference voltage value of the intermediate DC bus, the actual voltage value of the intermediate DC bus, and the current state of the electric control handle; Based on the reference voltage value of the intermediate DC bus and the actual voltage value of the intermediate DC bus, the braking chopper duty cycle at the current moment and the braking chopper duty cycle at the previous moment are determined using a PI control algorithm. The output braking chopper duty cycle is determined based on the current braking chopper duty cycle, the previous braking chopper duty cycle, the actual voltage value of the intermediate DC bus, and the current state of the electric control handle. The braking resistor is controlled to discharge at the duty cycle of the output braking chopper.

[0006] Optionally, the output braking chopper duty cycle is determined based on the current braking chopper duty cycle, the previous braking chopper duty cycle, the actual voltage value of the intermediate DC bus, and the current state of the electric control handle, including: When the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, the output braking chopper duty cycle is determined based on the braking chopper duty cycle at the current moment, the braking chopper duty cycle at the previous moment, and the current state of the electric control handle. When the actual voltage value of the intermediate DC bus is greater than the preset undervoltage warning value, the braking chopper duty cycle at the current moment is determined as the output braking chopper duty cycle.

[0007] Optionally, when the actual voltage value of the intermediate DC bus is less than or equal to a preset undervoltage warning value, the output braking chopper duty cycle is determined based on the current braking chopper duty cycle, the previous braking chopper duty cycle, and the current state of the electric control handle, including: When the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the electric control handle is in the rising phase, and the braking chopper duty cycle at the current moment is greater than the braking chopper duty cycle at the previous moment, then the braking chopper duty cycle at the current moment is determined as the output braking chopper duty cycle. When the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the electric control handle is in the rising phase, and the braking chopper duty cycle at the current moment is less than the braking chopper duty cycle at the previous moment, then the braking chopper duty cycle at the previous moment is determined as the output braking chopper duty cycle. When the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the electric control handle is in the falling phase, and the braking chopper duty cycle at the current moment is greater than or equal to the braking chopper duty cycle at the previous moment, then the braking chopper duty cycle at the previous moment is determined as the output braking chopper duty cycle. When the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the electric control handle is in the falling phase, and the braking chopper duty cycle at the current moment is less than the braking chopper duty cycle at the previous moment, then the braking chopper duty cycle at the current moment is determined as the output braking chopper duty cycle.

[0008] Optionally, the voltage control method for the intermediate DC bus further includes: When the actual voltage value of the intermediate DC bus is less than the preset undervoltage fault value, the main generator is controlled to supplement the intermediate DC bus with electrical energy.

[0009] Optionally, obtain the current state of the electric control handle, including: Get the current position of the electric control lever and the previous position of the electric control lever. The current state of the electric control handle is determined based on the current position of the electric control handle and the previous position of the electric control handle.

[0010] Optionally, the current state of the electric control lever is determined based on the current position of the electric control lever and the previous position of the electric control lever, including: When the current position of the electric lever is greater than or equal to the position of the electric lever in the previous moment, the current state of the electric lever is determined to be the rising phase. When the current position of the electric control lever is less than the position of the electric control lever at the previous moment, the current state of the electric control lever is determined to be the descent phase.

[0011] Secondly, the present invention also provides a voltage control device for an intermediate DC bus, applied to a train AC drive system, the train AC drive system comprising: a main generator, a rectifier module, an intermediate DC bus, and a braking resistor; the three-phase AC output terminal of the main generator is electrically connected to the AC input terminal of the rectifier module, and the DC output terminal of the rectifier module is electrically connected to the intermediate DC bus; the braking resistor is electrically connected between the positive and negative terminals of the intermediate DC bus; the voltage control device for the intermediate DC bus comprises: The parameter acquisition module is used to acquire the reference voltage value of the intermediate DC bus, the actual voltage value of the intermediate DC bus, and the current state of the electric control handle; The first duty cycle determination module is used to determine the braking chopper duty cycle at the current moment and the braking chopper duty cycle at the previous moment based on the reference voltage value of the intermediate DC bus and the actual voltage value of the intermediate DC bus, using a PI control algorithm. The second duty cycle determination module is used to determine the output braking chopper duty cycle based on the current braking chopper duty cycle, the previous braking chopper duty cycle, the actual voltage value of the intermediate DC bus, and the current state of the electric control handle. The discharge control module is used to control the braking resistor to discharge at the duty cycle of the output braking chopper.

[0012] Thirdly, the present invention also provides a computer storage medium storing computer instructions, which are used to cause a processor to execute the voltage control method for the intermediate DC bus described in the first aspect.

[0013] Fourthly, the present invention also provides a train AC drive system, comprising: a main generator, a rectifier module, an intermediate DC bus, a braking resistor, and a controller; The three-phase AC output terminal of the main generator is electrically connected to the AC input terminal of the rectifier module, and the DC output terminal of the rectifier module is electrically connected to the intermediate DC bus; the braking resistor is electrically connected between the positive and negative busbars of the intermediate DC bus. The controller is electrically connected to the main generator, the rectifier module, the intermediate DC bus, and the braking resistor, respectively; the controller is used to execute the voltage control method of the intermediate DC bus described in the first aspect.

[0014] Fifthly, the present invention also provides a train, characterized in that it includes at least an electric control handle and the train AC drive system described in the fourth aspect; The electric control handle is equipped with a handle detection sensor, which is used to detect the gear position of the electric control handle in real time. The handle detection sensor is connected to the controller of the train's AC drive system.

[0015] The technical solution of this invention obtains the reference voltage value of the intermediate DC bus, the actual voltage value of the intermediate DC bus, and the current state of the electric brake handle. Based on the reference voltage value and the actual voltage value of the intermediate DC bus, and using a PI control algorithm, it determines the braking chopper duty cycle at the current moment and the braking chopper duty cycle at the previous moment. Based on the braking chopper duty cycle at the current moment, the braking chopper duty cycle at the previous moment, the actual voltage value of the intermediate DC bus, and the current state of the electric brake handle, it determines the output braking chopper duty cycle and controls the braking resistor to discharge according to the output braking chopper duty cycle. This ensures that the voltage of the intermediate DC bus is controlled within a reasonable range, avoiding overvoltage, undervoltage, and abnormal fluctuations in the intermediate DC bus voltage, thereby improving the stability of the train's AC drive system and enhancing the stability of train operation and passenger comfort. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a train AC drive system provided in an embodiment of the present invention; Figure 2 This is a schematic flowchart of a voltage control method for an intermediate DC bus provided in Embodiment 2 of the present invention; Figure 3 This is a schematic flowchart of a voltage control method for an intermediate DC bus provided in Embodiment 3 of the present invention; Figure 4 This is a schematic flowchart of a voltage control method for an intermediate DC bus provided in Embodiment 4 of the present invention; Figure 5 This is a schematic flowchart of a voltage control method for an intermediate DC bus provided in Embodiment 5 of the present invention; Figure 6 This is a schematic diagram of the structure of a voltage control device for an intermediate DC bus provided in an embodiment of the present invention. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0018] The terminology used in the embodiments of this invention is for the purpose of describing specific embodiments only and is not intended to limit the invention. It should be noted that directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this invention. Furthermore, in the context, it should be understood that when referring to an element being formed "on" or "below" another element, it can be formed not only directly on or below the other element, but also indirectly on or below it through intermediate elements. The terms "first," "second," etc., are used for descriptive purposes only and do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0019] The term "comprising" and its variations as used in this invention are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment".

[0020] It should be noted that the concepts of "first" and "second" mentioned in this invention are only used to distinguish the corresponding contents and are not used to limit the order or interdependence.

[0021] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0022] Example 1 Figure 1 This is a schematic diagram of the structure of a train AC drive system provided in an embodiment of the present invention, as shown below. Figure 1 As shown, the train AC drive system includes a main generator 10, a rectifier module 20, an intermediate DC bus 30, a braking resistor 40, and a controller (not shown in the figure). The three-phase AC output terminal of the main generator 10 is electrically connected to the AC input terminal of the rectifier module 20, and the DC output terminal of the rectifier module 20 is electrically connected to the intermediate DC bus 30. The braking resistor 40 is electrically connected between the positive and negative bus of the intermediate DC bus 30. The controller is electrically connected to the main generator 10, the rectifier module 20, the intermediate DC bus 30, and the braking resistor 40. The controller is used to execute the voltage control method of the intermediate DC bus in any embodiment of the present invention.

[0023] When the train is in traction mode, the main generator 10 outputs three-phase AC power. The rectifier module 20 converts the AC power into DC power and transmits it to the intermediate DC bus 30. The high-voltage DC power from the intermediate DC bus 30 can be inverted into three-phase AC power by the traction converter circuit 50 and used to drive the traction motor 60. The traction motor 60 converts electrical energy into mechanical energy to drive the train. The train's AC drive system also includes a train power supply module 70 and an auxiliary converter module 80. The train power supply module 70 uses the power from the intermediate DC bus 30 to power the train's lighting, air conditioning, and other electrical equipment. The auxiliary converter module 80... The auxiliary converter module 80 can convert the DC power from the intermediate DC bus 30 into constant voltage and constant frequency AC power and supply power to constant voltage and constant frequency equipment. The auxiliary converter module 80 can also convert the DC power from the intermediate DC bus 30 into variable voltage and variable frequency AC power and supply power to variable voltage and variable frequency equipment. The auxiliary converter module 80 is also electrically connected to the excitation controller. The excitation controller changes the output frequency and power generation of the main generator 10 by adjusting the excitation current of the excitation winding of the main generator 10. The auxiliary converter module 80 is also connected to the charger. The auxiliary converter module 80 can convert high voltage DC power into 110V low voltage DC power and supply power to the train equipment through the charger.

[0024] When the driver shifts the electric brake lever to the next position, the train is in electric braking mode. The traction motor 60 switches to generator mode, and the traction converter circuit 50 converts the kinetic energy of the traction motor 60 into three-phase AC power, which is then supplied to the intermediate DC bus 30. The power of the intermediate DC bus 30 is used to power the train power supply module 70 and the auxiliary converter module 80. Excess power from the intermediate DC bus 30 can be dissipated in the braking resistor 40 through the brake chopper 90. The brake fan 100 is connected in parallel across the braking resistor 40 to provide air cooling for the braking resistor 40, thereby improving the operational stability of the train's AC drive system.

[0025] In this embodiment, the train AC drive system can synchronously distribute the power from the intermediate DC bus to the traction converter circuit, the train power supply module, and the auxiliary converter module when the train is in traction mode, thus realizing integrated centralized power supply for the train. When the train is in electric braking mode, it can prioritize supplying the power from the intermediate DC bus to the train power supply module and the auxiliary converter module. At the same time, the remaining power from the intermediate DC bus can be consumed in the braking resistor through the braking chopper, thereby improving the stability of the train AC drive system.

[0026] It is understood that the controller in the train AC drive system provided in the embodiments of the present invention can be used to execute the voltage control method of the intermediate DC bus provided in any embodiment of the present invention. Therefore, the controller of the train AC drive system has the relevant functional structure for executing the voltage control method of the intermediate DC bus provided in any embodiment of the present invention, and can achieve the same beneficial effect as the voltage control method of the intermediate DC bus provided in the embodiments of the present invention. For details, please refer to the following description.

[0027] Example 2 Figure 2 This is a flowchart illustrating a voltage control method for an intermediate DC bus according to Embodiment 2 of the present invention. This embodiment can be used to improve the stability of the intermediate DC bus voltage. The voltage control method for the intermediate DC bus can be executed by a voltage control device for the intermediate DC bus. This voltage control device can be implemented in software and / or hardware, and is generally integrated into the controller of the train's AC drive system, such as... Figure 2 As shown, the voltage control method for the intermediate DC bus includes: S110: Obtain the reference voltage value of the intermediate DC bus, the actual voltage value of the intermediate DC bus, and the current status of the electric control handle.

[0028] Among them, the reference voltage value of the intermediate DC bus is the ideal bus voltage value corresponding to the position of the electric brake lever; the actual voltage value of the intermediate DC bus refers to the instantaneous operating voltage value of the intermediate DC bus; the current state of the electric brake lever refers to the upward or downward state of the electric brake lever, and the current state of the electric brake lever reflects the driver's braking intention.

[0029] Specifically, after determining the current position of the electric control lever, the reference voltage value of the intermediate DC bus corresponding to the current position of the electric control lever can be determined by looking up a table; the intermediate DC bus is also connected to a voltage sensor, which can detect the actual voltage value of the intermediate DC bus in real time; the current state of the electric control lever can be determined based on the previous position and the current position of the electric control lever.

[0030] S120. Based on the reference voltage value and the actual voltage value of the intermediate DC bus, determine the braking chopper duty cycle at the current moment and the braking chopper duty cycle at the previous moment using the PI control algorithm.

[0031] Among them, the PI control algorithm is a commonly used feedback control algorithm. It dynamically adjusts the output braking chopper duty cycle by calculating the deviation between the reference voltage value and the actual voltage value of the intermediate DC bus in real time. After determining the reference voltage value and the actual voltage value of the intermediate DC bus, the braking chopper duty cycle at the current moment and the braking chopper duty cycle at the previous moment can be determined based on the PI control algorithm. Then, the braking chopper duty cycle at the current moment and the braking chopper duty cycle at the previous moment can be used to control the energy consumption of the braking resistor and avoid voltage oscillation of the intermediate DC bus.

[0032] S130. Determine the output braking chopper duty cycle based on the current braking chopper duty cycle, the previous braking chopper duty cycle, the actual voltage value of the intermediate DC bus, and the current state of the electric control handle.

[0033] Specifically, after determining the braking chopper duty cycle at the current moment and the braking chopper duty cycle at the previous moment, the braking chopper duty cycle determined based on the PI control algorithm can be set by combining the actual voltage value of the intermediate DC bus and the current state of the electric brake handle, so as to determine the dynamically smooth output braking chopper duty cycle and avoid voltage oscillation of the intermediate DC bus caused by the electric brake handle gear adjustment process.

[0034] S140, control the braking resistor to discharge using the output braking chopper duty cycle.

[0035] Specifically, after determining the output braking chopper duty cycle, the braking chopper can convert the output braking chopper duty cycle into a corresponding PWM drive signal, thereby controlling the braking resistor to release excess electrical energy from the intermediate DC bus, so that the voltage of the intermediate DC bus is controlled within a reasonable range, avoiding overvoltage, undervoltage and abnormal fluctuations in the intermediate DC bus voltage.

[0036] This embodiment acquires the reference voltage value of the intermediate DC bus, the actual voltage value of the intermediate DC bus, and the current state of the electric brake handle. Based on the reference voltage value and the actual voltage value of the intermediate DC bus, and using a PI control algorithm, it determines the braking chopper duty cycle at the current moment and the braking chopper duty cycle at the previous moment. Based on the current braking chopper duty cycle, the previous braking chopper duty cycle, the actual voltage value of the intermediate DC bus, and the current state of the electric brake handle, it determines the output braking chopper duty cycle and controls the braking resistor to discharge at the output braking chopper duty cycle. This ensures that the voltage of the intermediate DC bus is controlled within a reasonable range, avoiding overvoltage, undervoltage, and abnormal fluctuations in the intermediate DC bus voltage. This improves the stability of the train's AC drive system and enhances the stability of train operation and passenger comfort.

[0037] Example 3 Figure 3 This is a flowchart illustrating a voltage control method for an intermediate DC bus provided in Embodiment 3 of the present invention. Based on the above embodiments, this embodiment provides a detailed explanation of the method for determining the output braking chopper duty cycle, such as... Figure 3 As shown, the voltage control method for the intermediate DC bus includes: S210: Obtain the reference voltage value of the intermediate DC bus, the actual voltage value of the intermediate DC bus, and the current status of the electric control handle.

[0038] S220. Based on the reference voltage value and the actual voltage value of the intermediate DC bus, determine the braking chopper duty cycle at the current moment and the braking chopper duty cycle at the previous moment using the PI control algorithm.

[0039] S230. When the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, the output braking chopper duty cycle is determined based on the current braking chopper duty cycle, the previous braking chopper duty cycle, and the current state of the electric control handle.

[0040] Specifically, when the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, it indicates that the voltage of the intermediate DC bus may not be able to guarantee the normal power supply of the train power supply module and auxiliary converter module, and there is a risk of undervoltage on the intermediate DC bus. The output braking chopper duty cycle can be determined based on the current braking chopper duty cycle, the braking chopper duty cycle of the previous moment, and the current state of the electric brake handle. For example, the preset undervoltage warning value can be 1450V.

[0041] In an optional embodiment, when the actual voltage value of the intermediate DC bus is less than or equal to a preset undervoltage warning value, the output braking chopping duty cycle is determined based on the current braking chopping duty cycle, the previous braking chopping duty cycle, and the current state of the electric control handle. This includes: when the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the electric control handle is in the rising phase, and the current braking chopping duty cycle is greater than the previous braking chopping duty cycle, then the current braking chopping duty cycle is determined as the output braking chopping duty cycle; when the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the electric control handle is in the rising phase, and the current braking chopping duty cycle is greater than the previous braking chopping duty cycle, then the current braking chopping duty cycle is determined as the output braking chopping duty cycle; when the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the electric control handle is in the rising phase, and the current braking chopping duty cycle is greater than the previous braking chopping duty cycle, then the current braking chopping duty cycle is determined as the output braking chopping duty cycle; If the duty cycle of the braking chopper is less than the duty cycle of the braking chopper at the previous moment, then the duty cycle of the braking chopper at the previous moment is determined as the output braking chopper duty cycle. When the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the electric control handle is in the falling phase, and the duty cycle of the braking chopper at the current moment is greater than or equal to the duty cycle of the braking chopper at the previous moment, then the duty cycle of the braking chopper at the previous moment is determined as the output braking chopper duty cycle. When the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the electric control handle is in the falling phase, and the duty cycle of the braking chopper at the current moment is less than the duty cycle of the braking chopper at the previous moment, then the duty cycle of the braking chopper at the current moment is determined as the output braking chopper duty cycle.

[0042] Specifically, when the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the electric brake lever is in the rising stage, it indicates that the driver is increasing the braking force. The voltage output from the traction motor to the intermediate DC bus should gradually increase. To avoid voltage fluctuations in the intermediate DC bus, the output braking chopper duty cycle at the current moment should be greater than or equal to the output braking chopper duty cycle at the previous moment. Therefore, if the braking chopper duty cycle at the current moment is greater than the braking chopper duty cycle at the previous moment, the braking chopper duty cycle at the current moment is determined as the output braking chopper duty cycle; if the braking chopper duty cycle at the current moment is less than the braking chopper duty cycle at the previous moment, the braking chopper duty cycle at the previous moment is determined as the output braking chopper duty cycle.

[0043] If the current state of the electric brake lever is in the descending phase, it means that the driver is reducing the braking force. The voltage output from the traction motor to the intermediate DC bus should gradually decrease. To avoid voltage fluctuations in the intermediate DC bus, the current output braking chopper duty cycle should be less than or equal to the previous output braking chopper duty cycle. Therefore, if the current braking chopper duty cycle is greater than or equal to the previous braking chopper duty cycle, the previous braking chopper duty cycle is determined as the output braking chopper duty cycle; if the current braking chopper duty cycle is less than the previous braking chopper duty cycle, the current braking chopper duty cycle is determined as the output braking chopper duty cycle.

[0044] S240. When the actual voltage value of the intermediate DC bus is greater than the preset undervoltage warning value, the braking chopper duty cycle at the current moment is determined as the output braking chopper duty cycle.

[0045] Specifically, when the actual voltage value of the intermediate DC bus is greater than the preset undervoltage warning value, it indicates that the voltage of the intermediate DC bus can guarantee the normal power supply of the train power supply module and auxiliary converter module, there is no risk of undervoltage on the intermediate DC bus, and the voltage fluctuation is frequent and low. Therefore, the current braking chopper duty cycle can be directly determined as the output braking chopper duty cycle. For example, the preset undervoltage warning value could be 1450V.

[0046] S250 controls the braking resistor to discharge using the output braking chopper duty cycle.

[0047] This embodiment determines the output braking chopper duty cycle based on the current braking chopper duty cycle, the previous braking chopper duty cycle, and the current state of the electric brake handle when the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value; and determines the current braking chopper duty cycle as the output braking chopper duty cycle when the actual voltage value of the intermediate DC bus is greater than the preset undervoltage warning value. This effectively avoids fluctuations in the intermediate DC bus voltage under different operating conditions, and improves the stability of train operation while ensuring the braking chopper output control capability.

[0048] Example 4 Figure 4 This is a flowchart illustrating a voltage control method for an intermediate DC bus according to Embodiment 4 of the present invention. Based on the above embodiments, this embodiment provides a detailed description of the scenario where the main generator supplements power to the intermediate DC bus. Figure 4 As shown, the voltage control method for the intermediate DC bus includes: S310: Obtain the reference voltage value of the intermediate DC bus, the actual voltage value of the intermediate DC bus, and the current status of the electric control handle.

[0049] S320. Based on the reference voltage value and the actual voltage value of the intermediate DC bus, determine the braking chopper duty cycle at the current moment and the braking chopper duty cycle at the previous moment using the PI control algorithm.

[0050] S330. Determine the output braking chopper duty cycle based on the current braking chopper duty cycle, the previous braking chopper duty cycle, the actual voltage value of the intermediate DC bus, and the current state of the electric control handle.

[0051] S340 controls the braking resistor to discharge using the output braking chopper duty cycle.

[0052] S350: When the actual voltage value of the intermediate DC bus is less than the preset undervoltage fault value, control the main generator to supplement the intermediate DC bus with power.

[0053] Specifically, when the actual voltage of the intermediate DC bus is less than the preset undervoltage fault value, it indicates that the power consumption of the train power supply module and auxiliary converter module exceeds the feedback energy of the traction motor, leading to a drop in the voltage of the intermediate DC bus. At this time, the main generator is controlled to supplement the intermediate DC bus with power to maintain its voltage stability, ensuring power supply to the train power supply module and auxiliary converter module, and preventing an input undervoltage fault on the intermediate DC bus. For example, the preset undervoltage fault value could be 1100V.

[0054] This embodiment controls the main generator to supplement the intermediate DC bus with power when the actual voltage value of the intermediate DC bus is less than the preset undervoltage fault value. This maintains the voltage stability of the intermediate DC bus, ensures the power supply of the train power supply module and auxiliary converter module, avoids input undervoltage faults in the intermediate DC bus, and improves the stability of train operation and passenger comfort.

[0055] Example 5 Figure 5 This is a flowchart illustrating a voltage control method for an intermediate DC bus according to Embodiment 5 of the present invention. Based on the above embodiments, this embodiment provides a detailed explanation of the method for obtaining the current state of the control handle, such as... Figure 5 As shown, the voltage control method for the intermediate DC bus includes: S410: Obtain the reference voltage value and the actual voltage value of the intermediate DC bus.

[0056] S420: Obtain the current position of the electric control lever and the previous position of the electric control lever.

[0057] The electric brake lever has multiple positions; the higher the position of the electric brake lever, the faster the train decelerates.

[0058] S430. Determine the current state of the electric control lever based on the current position of the electric control lever and the previous position of the electric control lever.

[0059] Specifically, the electric brake lever is equipped with a lever detection sensor, which can detect the gear position of the electric brake lever in real time. After obtaining the current gear position and the previous gear position, the current state of the electric brake lever can be determined, thereby determining the driver's braking intention.

[0060] In an optional embodiment, determining the current state of the electric control lever based on the current lever position and the previous lever position includes: determining the current state of the electric control lever as an ascending phase when the current lever position is greater than or equal to the previous lever position; and determining the current state of the electric control lever as a descending phase when the current lever position is less than the previous lever position.

[0061] Specifically, when the current position of the electric brake lever is greater than or equal to the position of the electric brake lever at the previous moment, it indicates that the driver is increasing the braking force. The current state of the electric brake lever is in the rising phase, and the voltage output from the traction motor to the intermediate DC bus gradually increases. When the current position of the electric brake lever is less than the position of the electric brake lever at the previous moment, it indicates that the driver is decreasing the braking force. The current state of the electric brake lever is in the falling phase, and the voltage output from the traction motor to the intermediate DC bus gradually decreases.

[0062] S440. Based on the reference voltage value and the actual voltage value of the intermediate DC bus, determine the braking chopper duty cycle at the current moment and the braking chopper duty cycle at the previous moment using the PI control algorithm.

[0063] S450: Determine the output braking chopper duty cycle based on the current braking chopper duty cycle, the previous braking chopper duty cycle, the actual voltage value of the intermediate DC bus, and the current state of the electric control handle.

[0064] S460 controls the braking resistor to discharge using the output braking chopper duty cycle.

[0065] This embodiment obtains the current and previous positions of the electric brake lever and determines its current state based on these positions. This allows the determination of the driver's braking intention and the trend of the intermediate DC bus voltage change, providing data support for determining the output braking chopper duty cycle.

[0066] Example 6 Figure 6This is a schematic diagram of the structure of a voltage control device for an intermediate DC bus provided in an embodiment of the present invention. This voltage control device for the intermediate DC bus can be implemented by software and / or hardware, and is generally integrated into the controller of the train's AC drive system, such as... Figure 6 As shown, the voltage control device for the intermediate DC bus includes: The parameter acquisition module 610 is used to acquire the reference voltage value of the intermediate DC bus, the actual voltage value of the intermediate DC bus, and the current status of the electric control handle; The first duty cycle determination module 620 is used to determine the braking chopping duty cycle at the current moment and the braking chopping duty cycle at the previous moment based on the reference voltage value of the intermediate DC bus and the actual voltage value of the intermediate DC bus, using a PI control algorithm. The second duty cycle determination module 630 is used to determine the output braking chopper duty cycle based on the current braking chopper duty cycle, the previous braking chopper duty cycle, the actual voltage value of the intermediate DC bus, and the current state of the electric control handle. The discharge control module 640 is used to control the braking resistor to discharge by outputting the braking chopper duty cycle.

[0067] Optionally, the second duty cycle determination module 630 may include a first output braking chopper duty cycle determination unit and a second output braking chopper duty cycle determination unit; the first output braking chopper duty cycle determination unit is used to determine the output braking chopper duty cycle based on the current braking chopper duty cycle, the previous braking chopper duty cycle, and the current state of the electric control handle when the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value; the second output braking chopper duty cycle determination unit is used to determine the current braking chopper duty cycle as the output braking chopper duty cycle when the actual voltage value of the intermediate DC bus is greater than the preset undervoltage warning value.

[0068] Optionally, the first output braking chopper duty cycle determination unit is specifically used for: when the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the control handle is in the rising phase, and the braking chopper duty cycle at the current moment is greater than the braking chopper duty cycle at the previous moment, then the braking chopper duty cycle at the current moment is determined as the output braking chopper duty cycle; when the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the control handle is in the rising phase, and the braking chopper duty cycle at the current moment is less than the braking chopper duty cycle at the previous moment, then the braking chopper duty cycle at the previous moment is determined. The output braking chopper duty cycle is determined as follows: When the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the electric control handle is in the falling phase, and the braking chopper duty cycle at the current moment is greater than or equal to the braking chopper duty cycle at the previous moment, then the braking chopper duty cycle at the previous moment is determined as the output braking chopper duty cycle; when the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the electric control handle is in the falling phase, and the braking chopper duty cycle at the current moment is less than the braking chopper duty cycle at the previous moment, then the braking chopper duty cycle at the current moment is determined as the output braking chopper duty cycle.

[0069] Optionally, the voltage control device for the intermediate DC bus also includes a power replenishment module; the power replenishment module is used to control the main generator to replenish power to the intermediate DC bus when the actual voltage value of the intermediate DC bus is less than the preset undervoltage fault value.

[0070] Optionally, the parameter acquisition module 610 may include a gear position determination unit and a state determination unit; the gear position determination unit is used to acquire the gear position of the electric lever at the current moment and the gear position of the electric lever at the previous moment; the state determination unit is used to determine the current state of the electric lever based on the gear position of the electric lever at the current moment and the gear position of the electric lever at the previous moment.

[0071] Optionally, the state determination unit is specifically used to: determine the current state of the electric control handle as an ascending phase when the current position of the electric control handle is greater than or equal to the position of the electric control handle in the previous moment; and determine the current state of the electric control handle as a descending phase when the current position of the electric control handle is less than the position of the electric control handle in the previous moment.

[0072] It is understood that, since the voltage control device for the intermediate DC bus described above is capable of executing the voltage control method for the intermediate DC bus in the embodiments of the present invention, those skilled in the art can understand the specific implementation and various variations of the voltage control device for the intermediate DC bus in this embodiment based on the voltage control method for the intermediate DC bus described in the embodiments of the present invention. Therefore, how the voltage control device for the intermediate DC bus implements the voltage control method for the intermediate DC bus in the embodiments of the present invention will not be described in detail here. Any device used by those skilled in the art to implement the voltage control method for the intermediate DC bus in the embodiments of the present invention falls within the scope of protection of this application.

[0073] Example 7 The present invention also provides a computer storage medium storing computer instructions. The computer instructions are used to cause a processor to execute the voltage control method of the intermediate DC bus in any embodiment of the present invention, and thus have the beneficial effects of the corresponding voltage control method of the intermediate DC bus. The similarities can be referred to the above description, and will not be repeated here.

[0074] In the context of this invention, a computer storage medium can be a tangible medium that may contain or store computer programs for use by or in conjunction with an instruction execution system, apparatus, or device. The computer storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination thereof.

[0075] Example 8 The present invention also provides a train, including at least an electric handle and a train AC drive system according to any embodiment of the present invention; the electric handle is provided with a handle detection sensor, which is used to detect the gear position of the electric handle in real time; the handle detection sensor is connected to the controller of the train AC drive system; the train includes at least an electric handle and a train AC drive system according to any embodiment of the present invention, and therefore has the beneficial effects of the corresponding train AC drive system. The similarities can be referred to the above description, and will not be repeated here.

[0076] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A voltage control method for an intermediate DC bus, applied to a train AC drive system, characterized in that, The train's AC drive system includes: a main generator, a rectifier module, an intermediate DC bus, and a braking resistor; the three-phase AC output terminal of the main generator is electrically connected to the AC input terminal of the rectifier module, and the DC output terminal of the rectifier module is electrically connected to the intermediate DC bus; the braking resistor is electrically connected between the positive and negative terminals of the intermediate DC bus; the voltage control method for the intermediate DC bus includes: Obtain the reference voltage value of the intermediate DC bus, the actual voltage value of the intermediate DC bus, and the current state of the electric control handle; Based on the reference voltage value of the intermediate DC bus and the actual voltage value of the intermediate DC bus, the braking chopper duty cycle at the current moment and the braking chopper duty cycle at the previous moment are determined using a PI control algorithm. The output braking chopper duty cycle is determined based on the current braking chopper duty cycle, the previous braking chopper duty cycle, the actual voltage value of the intermediate DC bus, and the current state of the electric control handle. The braking resistor is controlled to discharge at the duty cycle of the output braking chopper.

2. The voltage control method for the intermediate DC bus according to claim 1, characterized in that, The output braking chopper duty cycle is determined based on the current braking chopper duty cycle, the previous braking chopper duty cycle, the actual voltage value of the intermediate DC bus, and the current state of the control handle, including: When the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, the output braking chopper duty cycle is determined based on the braking chopper duty cycle at the current moment, the braking chopper duty cycle at the previous moment, and the current state of the electric control handle. When the actual voltage value of the intermediate DC bus is greater than the preset undervoltage warning value, the braking chopper duty cycle at the current moment is determined as the output braking chopper duty cycle.

3. The voltage control method for the intermediate DC bus according to claim 2, characterized in that, When the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, the output braking chopper duty cycle is determined based on the current braking chopper duty cycle, the previous braking chopper duty cycle, and the current state of the electric control handle, including: When the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the electric control handle is in the rising phase, and the braking chopper duty cycle at the current moment is greater than the braking chopper duty cycle at the previous moment, then the braking chopper duty cycle at the current moment is determined as the output braking chopper duty cycle. When the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the electric control handle is in the rising phase, and the braking chopper duty cycle at the current moment is less than the braking chopper duty cycle at the previous moment, then the braking chopper duty cycle at the previous moment is determined as the output braking chopper duty cycle. When the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the electric control handle is in the falling phase, and the braking chopper duty cycle at the current moment is greater than or equal to the braking chopper duty cycle at the previous moment, then the braking chopper duty cycle at the previous moment is determined as the output braking chopper duty cycle. When the actual voltage value of the intermediate DC bus is less than or equal to the preset undervoltage warning value, if the current state of the electric control handle is in the falling phase, and the braking chopper duty cycle at the current moment is less than the braking chopper duty cycle at the previous moment, then the braking chopper duty cycle at the current moment is determined as the output braking chopper duty cycle.

4. The voltage control method for the intermediate DC bus according to claim 1, characterized in that, Also includes: When the actual voltage value of the intermediate DC bus is less than the preset undervoltage fault value, the main generator is controlled to supplement the intermediate DC bus with electrical energy.

5. The voltage control method for the intermediate DC bus according to claim 1, characterized in that, Obtain the current state of the electric control handle, including: Get the current position of the electric control lever and the previous position of the electric control lever. The current state of the electric control handle is determined based on the current position of the electric control handle and the previous position of the electric control handle.

6. The voltage control method for the intermediate DC bus according to claim 5, characterized in that, The current state of the electric control lever is determined based on the current position of the electric control lever and the previous position of the electric control lever, including: When the current position of the electric lever is greater than or equal to the position of the electric lever in the previous moment, the current state of the electric lever is determined to be the rising phase. When the current position of the electric control lever is less than the position of the electric control lever at the previous moment, the current state of the electric control lever is determined to be the descent phase.

7. A voltage control device for an intermediate DC bus, applied to a train AC drive system, characterized in that, The train's AC drive system includes: a main generator, a rectifier module, an intermediate DC bus, and a braking resistor; the three-phase AC output terminal of the main generator is electrically connected to the AC input terminal of the rectifier module, and the DC output terminal of the rectifier module is electrically connected to the intermediate DC bus; the braking resistor is electrically connected between the positive and negative terminals of the intermediate DC bus; the voltage control device for the intermediate DC bus includes: The parameter acquisition module is used to acquire the reference voltage value of the intermediate DC bus, the actual voltage value of the intermediate DC bus, and the current state of the electric control handle; The first duty cycle determination module is used to determine the braking chopper duty cycle at the current moment and the braking chopper duty cycle at the previous moment based on the reference voltage value of the intermediate DC bus and the actual voltage value of the intermediate DC bus, using a PI control algorithm. The second duty cycle determination module is used to determine the output braking chopper duty cycle based on the current braking chopper duty cycle, the previous braking chopper duty cycle, the actual voltage value of the intermediate DC bus, and the current state of the electric control handle. The discharge control module is used to control the braking resistor to discharge at the duty cycle of the output braking chopper.

8. A computer storage medium, characterized in that, The computer storage medium stores computer instructions, which are used to cause the processor to execute the voltage control method for the intermediate DC bus as described in any one of claims 1-6.

9. A train AC drive system, characterized in that, include: Main generator, rectifier module, intermediate DC bus, braking resistor and controller; The three-phase AC output terminal of the main generator is electrically connected to the AC input terminal of the rectifier module, and the DC output terminal of the rectifier module is electrically connected to the intermediate DC bus; the braking resistor is electrically connected between the positive and negative busbars of the intermediate DC bus. The controller is electrically connected to the main generator, the rectifier module, the intermediate DC bus, and the braking resistor respectively; the controller is used to execute the voltage control method of the intermediate DC bus according to any one of claims 1-6.

10. A train, characterized in that, It includes at least an electric control handle and the train AC drive system as described in claim 9; The electric control handle is equipped with a handle detection sensor, which is used to detect the gear position of the electric control handle in real time. The handle detection sensor is connected to the controller of the train's AC drive system.

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