High voltage frequency converter system

Abstract

The embodiments of the present disclosure relate to a high-voltage frequency converter system. The high-voltage frequency converter system comprises a first filtering unit, a rectification and feedback unit, a direct-current bus unit, an inversion unit, a second filtering unit and a controller unit, and is configured to be connected between an input voltage end and an electric motor unit, wherein the first filtering unit is connected between the input voltage end and the rectification and feedback unit, comprises a filter and a common-mode reactor, and is configured to enable an input voltage to be adjusted to meet the standard that the voltage of the rectification and feedback unit meets; and the rectification and feedback unit is connected between the first filtering unit and the direct-current bus unit, comprises a bridge circuit consisting of an IGBT-based active front-end frequency converter, and is configured to execute conversion between an alternating-current voltage signal and a direct-current voltage signal.

Description

High-voltage inverter system Technical Field

[0001] The present invention relates to the field of frequency converters, and in particular to a high-voltage frequency converter system. Background Art

[0002] Key components of large chute belt conveyors, such as high-power soft-start devices, rely entirely on imports. This increases equipment investment, makes after-sales service difficult, and makes spare parts difficult to source. Furthermore, currently, for large chute belt conveyors with a single drive power of 800kW or above, the soft-start method often involves direct no-load starting of the motor, coupled with a CST or speed-regulating hydraulic coupling. The drawback is that soft-starting with a CST or speed-regulating hydraulic coupling has a significant impact on the mechanical equipment and the power grid. While it generally meets soft-start requirements, it lacks speed control, and its reliability, speed regulation, power balance, and speed synchronization performance all fall short of field requirements. Furthermore, maintenance is difficult and expensive. Most importantly, mechanical slip causes the motor to heat up rapidly at low speeds, making it impossible to perform low-speed belt testing on long chute belt conveyors.

[0003] Since 2004, China has been using high-voltage inverters as soft-start devices for large belt conveyors operating on non-explosion-proof working surfaces. This application has achieved remarkable results and is now widely adopted. However, currently, only low-voltage explosion-proof inverters are available for electrical soft-starting of chute belt conveyors. With the advancement of science and technology and the emergence of large-scale mines, there is an urgent need to develop high-power, high-voltage explosion-proof inverters to achieve soft-start.

[0004] Taking the production needs of a mine with an annual output of 30 million tons as an example, the underground supporting chute belt conveyor has a bandwidth of 1600mm, a belt speed of 5.0m / s, and a driving power of 3×1250+3×1250kW. If a flameproof and intrinsically safe high-voltage and high-power frequency conversion device is configured as a soft start method, the maximum transportation distance of the retractable chute belt conveyor will reach more than 6 kilometers.

[0005] At present, there are no mature high-voltage (10kV), high-power (2000kW) explosion-proof and intrinsically safe frequency conversion devices for mining in China. The fundamental reasons are twofold: first, China has not yet mastered the core technology for high-voltage frequency conversion speed regulation for constant torque loads. It is difficult to produce mining products with original imported high-voltage frequency converters from abroad. The quality is difficult to guarantee after disassembly, and service also becomes a problem. Secondly, how to quickly and effectively discharge tens of kilowatts of heat in a closed explosion-proof cavity without damaging the electronic components in the cavity is also a key technology. Summary of the Invention

[0006] To address these issues, this disclosure discloses a flameproof and safe inverter that utilizes low-voltage IGBT power modules to achieve bidirectional energy flow. Its switching frequency and reliability are significantly higher than those of similar products using high-voltage IGBTs or IGCTs. This inverter system adjusts the input power factor, eliminating harmonic pollution to the power grid, and feeds energy generated by the motor back to the grid, achieving energy savings.

[0007] According to a first aspect of the present disclosure, a high-voltage inverter system is provided, which includes a first filter unit, a rectifier feedback unit, a DC bus unit, an inverter unit, a second filter unit and a controller unit and is configured to be connected between an input voltage terminal and a motor unit, and is characterized in that: the first filter unit is connected between the input voltage terminal and the rectifier feedback unit, includes a filter and a common-mode inductor and is configured so that the input voltage is adjusted to meet the voltage compliance standard of the rectifier feedback unit; the rectifier feedback unit is connected between the first filter unit and the DC bus unit, includes a bridge circuit composed of an active front-end inverter based on IGBT and is configured to perform conversion between AC voltage signals and DC voltage signals; the DC bus unit is connected between the rectifier feedback unit and the inverter unit, includes a braking capacitor and a braking resistor and is configured to absorb the current that fails to be fed to the inverter unit. The electric energy of the motor in the electric state is absorbed by the DC bus unit and is fed back via the rectifier feedback unit; the inverter unit is connected between the DC bus unit and the second filter unit, includes a bridge circuit composed of an active front-end inverter based on IGBT and is configured to perform conversion between AC voltage signals and DC voltage signals; the second filter unit is connected between the inverter unit and the motor unit, includes a filter and a common-mode inductor and is configured to receive an AC voltage signal from the inverter unit and adjust the received AC voltage signal to meet the voltage compliance standard of the motor unit; and the controller unit is connected to the first filter unit, the rectifier feedback unit, the DC bus unit, the inverter unit, and the second filter unit, and is configured to determine the working state of the motor and control the first filter unit, the rectifier feedback unit, the inverter unit and the second filter unit to perform high-voltage frequency conversion.

[0008] According to a second aspect of the present disclosure, a computing device is provided, comprising: at least one processor; and a memory communicatively connected to the at least one processor; the memory storing instructions executable by the at least one processor, the instructions being executed by the at least one processor so as to enable the at least one processor to execute the method of the first aspect of the present disclosure.

[0009] In a third aspect of the present disclosure, a non-transitory computer-readable storage medium storing computer instructions is provided, wherein the computer instructions are used to cause a computer to execute the method of the first aspect of the present disclosure.

[0010] In some embodiments, the high-voltage inverter system controls the first filtering unit, the rectifier feedback unit, the inverter unit, and the second filtering unit to perform high-voltage frequency conversion, including: in response to determining that the working state of the motor is the motoring state, the controller is configured to control the rectifier feedback unit to receive an AC voltage signal and convert the AC voltage signal into a DC voltage signal and feed it to the inverter unit via the DC bus unit, and also controls the inverter unit to receive the DC voltage signal from the DC bus unit and invert the DC voltage signal into an AC voltage signal with adjustable voltage and frequency and feed it to the motor, thereby controlling the operation of the AC motor; in response to determining that the working state of the motor is the power generation state, the controller is configured to control the inverter unit to receive the AC voltage signal generated by the motor and convert the AC voltage signal into a DC voltage signal and feed the DC voltage signal to the rectifier feedback unit via the DC bus unit, and also controls the rectifier feedback unit to invert the DC voltage signal into a sinusoidal AC voltage signal that is synchronized with the power grid and in the same phase as the power grid and feed the AC voltage signal to the power grid after the first filtering unit filters out high-order harmonics.

[0011] In some embodiments, the rectifier feedback unit and the inverter unit of the high-voltage inverter system perform conversion or inversion of DC voltage signals and AC voltage signals by triggering a bridge circuit composed of an active front-end inverter of the IGBT of the rectifier feedback unit and the inverter unit based on a predetermined trigger timing.

[0012] In some embodiments, the high-voltage inverter system further includes a cooling subsystem, characterized in that the cooling subsystem includes a main circulation module, a deionized water module and a water replenishment module.

[0013] In some embodiments, the main circulation module of the high-voltage inverter system is configured to provide power for the deionized water side circulation operation and to measure the pressure, temperature, flow rate and conductivity of the deionized water side operation.

[0014] In some embodiments, the deionized water module of the high-voltage inverter system is configured to dynamically remove dissolved electrolyte ions in the deionized water, thereby ensuring that the conductivity of the deionized water side of the cooling system meets the operating requirements of the inverter device.

[0015] In some embodiments, the cooling subsystem of the high-voltage inverter system further includes a water-to-water heat dissipation module, and the water-to-water heat dissipation module is configured to continuously and stably dissipate heat on the deionized water side into external water.

[0016] In some embodiments, the cooling subsystem of the high-voltage inverter system further includes a water-air heat dissipation module, which is configured to continuously and stably dissipate heat on the deionized water side into the air.

[0017] In some embodiments, the water replenishment module of the high-voltage inverter system is configured to add a corresponding volume of replenishment water to the deionized water side of the cooling system based on predetermined instructions.

[0018] In some embodiments, the high-voltage inverter system also includes an explosion-proof casing, wherein the inner cavity size, installation method, wall thickness of the explosion-proof casing, flange thickness and width of the explosion-proof casing, and thickness, height and arrangement of the reinforcement ribs of the explosion-proof casing are determined based on finite element analysis and the size of the high-voltage inverter system. The installation method includes pushing one side of the casing horizontally, a full-through door is opened on one side of the explosion-proof casing, an extendable guide rail is provided under the inner wall of the explosion-proof casing, and multiple inspection doors are provided in front of the explosion-proof casing.

[0019] In some embodiments, the controller unit of the high-voltage inverter system determines the operating state of the motor based on a machine learning algorithm.

[0020] Existing voltage-source flameproof and intrinsically safe inverter systems require a phase-shifting transformer at the front end due to their main circuit structure, resulting in a bulky external transformer. The IGBT-based inverter system provided in this disclosure generates DC bus voltage and feeds power back to the grid. Its transformerless design allows for direct cable entry, resulting in a compact, modular design and drawer-style structure for easy maintenance.

[0021] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. In the accompanying drawings, the same or similar reference numerals represent the same or similar elements.

[0023] FIG1 shows a schematic diagram of a frequency converter system according to an embodiment of the present disclosure.

[0024] FIG2 shows a schematic diagram of a first filtering unit of a frequency converter system according to an embodiment of the present disclosure.

[0025] FIG3 shows a schematic diagram of a rectifier feedback unit and an inverter unit of a frequency converter system according to an embodiment of the present disclosure.

[0026] FIG4 shows a schematic diagram of a cooling subsystem for an inverter system according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0027] The following description of exemplary embodiments of the present disclosure is made in conjunction with the accompanying drawings, including various details of the embodiments of the present disclosure to facilitate understanding. These details should be considered as merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0028] As used herein, the term "including" and its variations represent open inclusion, i.e., "including but not limited to." Unless otherwise stated, the term "or" means "and / or." The term "based on" means "based at least in part on." The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment." The term "another embodiment" means "at least one additional embodiment." The terms "first," "second," etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0029] FIG1 shows a schematic diagram of an inverter system according to an embodiment of the present disclosure. As shown in FIG1 , the high-voltage inverter system includes a first filter unit, a rectifier feedback unit, a DC bus unit, an inverter unit, a second filter unit, and a controller unit. In addition, it also includes some interface board transformers commonly used in the field. The high-voltage inverter system is configured to be connected between the input voltage terminal and the motor unit. Specifically, the input grid voltage is filtered by the first filter unit and output to the rectifier feedback unit, and the rectifier feedback unit rectifies the input AC power into DC power to the DC bus unit. Then it is converted into the voltage and frequency required by the motor through the inverter unit, and filtered by the second filter unit and output to the motor.

[0030] Correspondingly, the system can also realize the charging function from the motor to the power grid. The pre-charging transformer is used to pre-charge the DC bus unit to avoid inrush current when the flameproof and intrinsically safe inverter is started. The power interface board provides all analog measurement interfaces, digital measurement interfaces and IGBT trigger / monitoring signal interfaces. The power interface board includes a rectifier power port board and an inverter power interface board. The monitoring information of the first filter unit, the rectifier feedback unit, the inverter unit and the second filter unit is connected to the controller unit through the rectifier power port board. The monitoring information of the inverter unit and the second filter unit is connected to the controller through the inverter power interface board.

[0031] In one embodiment, the first filter unit of the high-voltage inverter system is connected between the input voltage terminal and the rectifier-feedback unit. The filter and common-mode reactor are configured to adjust the input voltage to meet the voltage compliance standards of the rectifier-feedback unit. The first filter unit comprises a filter circuit composed of capacitors, inductors, and resistors. This filter circuit limits common-mode currents and reduces harmonics, ensuring that the voltage input to the rectifier-feedback unit meets the standards.

[0032] Due to the presence of the first filtering unit, the flameproof and intrinsically safe inverter system of the present disclosure can perform voltage transformation without using a transformer.

[0033] Figure 2 shows a schematic diagram of the first filtering unit of the inverter system according to an embodiment of the present disclosure. As shown in Figure 2, the first filtering unit includes an LCL sine wave filter and a common-mode reactor. The LCL sine wave filter can improve harmonics so that it meets most international standards. The common-mode reactor can limit the common-mode current. Specifically, the LCL sine wave filter includes inductors L1 and L2, a DC resistor Rinf, and a capacitor C3, and the common-mode reactor includes a common-mode reactor inductor Lcm. The LCL sine wave filter and the common-mode reactor are designed and matched to form the first filtering unit. The first filtering unit cooperates with the rectifier feedback unit to realize dynamic tracking compensation on the grid side, and can compensate for both harmonics and reactive power.

[0034] In one embodiment, the rectifier feedback unit is connected between the first filter unit and the DC bus unit, includes a bridge circuit composed of an IGBT-based active front-end inverter, and is configured to perform conversion between AC voltage signals and DC voltage signals.

[0035] The rectifier-feedback unit is an IGBT-based active front-end with a nested neutral point piloted (NPP) topology. The rectifier-feedback unit used in this disclosure can be, for example, a three-level or five-level power module, thereby generating a three-level or five-level output voltage.

[0036] The rectifier feedback unit is used to convert DC voltage signals into AC voltage signals. It can not only convert the AC voltage signal of the grid power supply into DC voltage signals, but also feed back electrical energy to the grid.

[0037] In one embodiment, the DC bus unit is connected between the rectifier-feedback unit and the inverter unit, includes a braking capacitor and a braking resistor, and is configured to absorb electric energy that cannot be fed to the motor in the electric state and feed back the absorbed electric energy to the DC bus unit via the rectifier-feedback unit.

[0038] In one embodiment, the inverter unit is connected between the DC bus unit and the second filter unit, includes a bridge circuit composed of an IGBT-based active front-end inverter, and is configured to perform conversion between AC voltage signals and DC voltage signals.

[0039] Figure 3 shows a schematic diagram of the rectifier feedback unit and inverter unit of the inverter system according to an embodiment of the present disclosure. As shown in Figure 3, the inverter unit is used to convert DC voltage signals into AC voltage signals. The inverter unit can convert the DC voltage signal of the rectifier feedback unit into an AC voltage signal and transmit this AC voltage signal to the motor. The inverter unit adopts a nested neutral point piloted (NPP) topology and is a three-level or five-level power module, which can generate a three-level or five-level output voltage.

[0040] In one embodiment, a second filter unit is connected between the inverter unit and the motor unit. The filter unit includes a filter and a common-mode reactor and is configured to receive an AC voltage signal from the inverter unit and adjust the received AC voltage signal to meet the motor unit's voltage compliance standards. The second filter unit can be a DV / DT filter, which reduces switching transient overvoltages, thereby allowing the use of longer motor cables. DV / DT series filters are used to protect motors. Placed at the inverter output, they effectively extend the rise time of the PWM pulses at the inverter output, reduce the rate of voltage change, and effectively protect the motor's insulation.

[0041] The system also includes some auxiliary and control units, such as a controller unit. The controller unit can be a power electronic controller that can provide high-performance vector control calculations and is connected to the first filter unit, rectifier feedback unit, inverter unit, DC bus unit, and second filter unit to control the operation of the first filter unit, rectifier feedback unit, inverter unit, DC bus unit, and second filter unit.

[0042] In one embodiment, the controller unit is connected to the first filter unit, the rectifier feedback unit, the DC bus unit, the inverter unit, and the second filter unit, and is configured to determine the working state of the motor and control the first filter unit, the rectifier feedback unit, the inverter unit, and the second filter unit to perform high-voltage frequency conversion.

[0043] The frequency converter disclosed herein is a four-quadrant frequency converter. A four-quadrant frequency converter is one that can operate in both the motoring state and the generating state.

[0044] In one embodiment, for the electric state working in the first and third quadrants, the controller unit can be configured to control the rectifier feedback unit to receive the AC voltage signal and convert the AC voltage signal into a DC voltage signal and feed it to the inverter unit via the DC bus unit in response to determining that the working state of the motor is the electric state, and also control the inverter unit to receive the DC voltage signal from the DC bus unit and invert the DC voltage signal into an AC voltage signal with adjustable voltage and frequency and feed it to the motor, thereby controlling the operation of the AC motor.

[0045] Specifically, when the motor is operating in the electric state, the bridge circuit composed of controllable components such as IGBTs inside the rectifier feedback unit can control which path of the bridge is conductive during a certain period of time by controlling the triggering timing of the controllable components, thereby converting AC power into DC power and outputting it to the DC bus unit. The inverter unit obtains electrical energy from the DC bus unit and uses IGBT inverter technology to convert DC power into AC power with adjustable voltage and frequency to control the AC motor. At this time, energy flows from the grid power supply to the motor through the rectifier feedback unit circuit and the inverter unit circuit.

[0046] In one embodiment, for the power generation state operating in the second and fourth quadrants, the controller unit can be configured to control the inverter unit to receive the AC voltage signal generated by the motor and convert the AC voltage signal into a DC voltage signal and feed the DC voltage signal to the rectifier feedback unit via the DC bus unit in response to determining that the motor is in the power generation state, and also control the rectifier feedback unit to invert the DC voltage signal into a sinusoidal AC voltage signal that is synchronized with the power grid and in the same phase as the power grid and feed the AC voltage signal to the power grid after the first filter unit filters out high-order harmonics.

[0047] When the motor is operating in the generating state, the energy generated by the motor is fed back to the DC bus unit through the inverter unit. The rectifier feedback unit inverts the DC bus unit's energy DC voltage signal into a sinusoidal AC voltage signal synchronized with the grid and in phase. After the first filter unit filters out higher harmonics, the energy is fed back to the grid power supply, achieving energy conservation. At this time, energy flows from the motor through the inverter unit and rectifier feedback unit to the original input grid power supply.

[0048] Through the above technical solution, the inverter uses a low-voltage IGBT power module to achieve bidirectional energy flow. Its switching frequency and reliability are significantly higher than the high-voltage IGBT or IGCT used in similar products. On the one hand, it can adjust the input power factor and eliminate harmonic pollution to the power grid. On the other hand, it can feed the energy generated by the motor back to the power grid to achieve a complete energy-saving effect.

[0049] In one embodiment, a controller unit monitors the motor based on a machine learning algorithm to determine the motor's operating status. The controller unit may be connected to a sensor unit, such as a camera. Based on the sensor unit, the controller unit acquires multiple power generation state diagrams and motoring state diagrams of the motor and normalizes the power generation state diagrams and motoring state diagrams to obtain preprocessed images. The controller unit then cleans the preprocessed images based on the power generation state diagram and motoring state diagram datasets, dividing the cleaned power generation state diagram and motoring state diagram datasets into training and validation sets. Training and validation are iteratively performed until the accuracy of the trained power generation state diagram and motoring state diagram models reaches a threshold level, thereby acquiring validated power generation state diagram and motoring state diagram models. Finally, the images acquired by the sensors are input into the power generation state diagram and motoring state diagram models to determine whether the motor is in the power generation state or motoring state.

[0050] Specifically, the sensor unit can crop the power generation state diagram and the electric state diagram into image blocks of 128×3 voxels, and uniformly resample the cropped image blocks to an isotropic spacing of 0.9~0.945 mm / voxel. Iteratively performing the above training and verification until the accuracy of the trained power generation state diagram and electric state diagram models reaches a threshold level includes: using data enhancement to train the power generation state diagram and electric state diagram models, and using data enhancement includes performing random elastic deformation of cropping 0~0.015mm, performing small random scaling of 0.3~0.41 times, and small random rotation of -4°~+4°. Iteratively performing the above training and verification until the accuracy of the trained power generation state diagram and electric state diagram models reaches a threshold level also includes: using the Adam optimizer in deep learning to optimize the power generation state diagram and electric state diagram models, and the minimized objective loss function is set to the initial learning rate = 5 -4 , β1=0.1, β2=0.1, the training batch size is set to 2-8, the focal loss is set to α=0.15, γ=0.1, where β1, β2, α, and γ are parameters in the loss function. The Kaming initialization method can also be used to initialize the model parameters of the power generation state diagram and electric state diagram models.

[0051] Temperature is a critical factor that severely impacts the lifespan of all electrical components, especially semiconductor devices. All their parameter ratings are based on a specific temperature. Unlike most devices, which damage slowly and at inaccurate temperatures, in a VFD's inverter circuit, exceeding a certain temperature limit immediately damages the inverter diodes, and this temperature limit is often very accurate. Therefore, the failure rate of VFDs increases exponentially with increasing temperature, while their service life decreases exponentially with increasing temperature. The 10°C rule states that for every 10°C increase in ambient temperature, the average lifespan of an VFD is halved (its failure rate doubles).

[0052] The high-voltage inverter disclosed herein has a relatively large capacity and high heat dissipation. Heat accumulates in a fixed, enclosed space, necessitating urgent and important solutions for dissipating the inverter's heat, reducing temperature rise, and improving component reliability, thereby extending the equipment's service life. The heat dissipation problem of the main circuit power components in the inverter requires multiple approaches. The heat generation principle is analyzed, modeled, and simulated to produce a mathematical model. Based on this model, a corresponding heat dissipation structure is designed. Based on the heat dissipation structure, the heat dissipation effect is simulated, prototyped, and optimized, ultimately resulting in a heat dissipation device that meets standards and technical requirements.

[0053] Figure 4 shows a schematic diagram of a cooling subsystem for a frequency converter system according to an embodiment of the present disclosure. In some embodiments, the high-voltage frequency converter system further includes a cooling subsystem comprising a primary circulation module, a deionized water module, and a water replenishment module, and optionally further comprising a water-to-water cooling module and a water-to-air cooling module.

[0054] External heat exchanger, flexible cooling method. The device has a closed redundant water cooling system with two optional cooling methods: "water-to-water" and "water-to-air". The heat inside the inverter is carried out by the internal circulating water to the water-to-water heat exchanger. In the absence of external cooling water, the water-to-water heat exchanger can be bypassed and the water-to-air heat exchanger can be used. In relatively harsh heat dissipation conditions, both cooling methods can be used simultaneously.

[0055] In some embodiments, the main circulation module of the high-voltage inverter system is configured to provide power for the deionized water side circulation operation and to measure the pressure, temperature, flow rate, and conductivity of the deionized water side operation. The main circulation module provides power for the deionized water side circulation operation and to measure the pressure, temperature, flow rate, and conductivity of the deionized water side operation in real time.

[0056] In some embodiments, the deionized water module of the high-voltage inverter system is configured to dynamically remove dissolved electrolyte ions from the deionized water, thereby ensuring that the conductivity of the deionized water side of the cooling system meets the inverter's operating requirements. The deionized water module dynamically removes dissolved electrolyte ions from the water, ensuring that the conductivity of the deionized water side of the cooling subsystem meets the inverter's operating requirements.

[0057] In some embodiments, the cooling subsystem of the high-voltage inverter system also includes a water-to-water heat dissipation module, which is configured to continuously and stably dissipate heat from the deionized water side into external water. The water-to-water heat dissipation module continuously and stably dissipates heat from the deionized water side into the external water. The radiator must be maintained according to the maintenance manual. If a water-to-air heat dissipation module is used as the primary heat dissipation method and a water-to-water heat dissipation module is used as the secondary heat dissipation method, the external water flow rate must be ≥7.3 m³ / h, and the water supply pressure must be within a range of 4-6 bar.

[0058] In some embodiments, the cooling subsystem of the high-voltage inverter system further includes a water-to-air heat dissipation module configured to continuously and stably dissipate heat from the deionized water side into the air. The water-to-air heat dissipation module is selected when the ambient temperature is less than or equal to a threshold temperature, for example, 30°C, to continuously and stably dissipate heat from the deionized water side into the air.

[0059] In some embodiments, the water replenishment module of the high-voltage inverter system is configured to add a corresponding volume of replenishment water to the deionized water side of the cooling system based on a predetermined instruction. The water replenishment module automatically prompts an operator to manually perform a predetermined operation to add a certain volume of replenishment water to the deionized water side of the cooling subsystem.

[0060] In some embodiments, the high-voltage inverter system also includes an explosion-proof casing, wherein the inner cavity size, installation method, wall thickness of the explosion-proof casing, flange thickness and width of the explosion-proof casing, and thickness, height and arrangement of the reinforcement ribs of the explosion-proof casing are determined based on finite element analysis and the size of the high-voltage inverter system. The installation method includes pushing one side of the casing horizontally, a full-through door is opened on one side of the explosion-proof casing, an extendable guide rail is provided under the inner wall of the explosion-proof casing, and multiple inspection doors are provided in front of the explosion-proof casing.

[0061] In the design and development of flameproof enclosures, the traditional method is to use a large number of formulas to calculate basic parameters such as relevant materials, shell thickness, and door cover thickness based on the required external dimensions. This method cannot quickly obtain an optimized design solution, and it is very troublesome to modify the drawings. If a single dimension changes, all related components need to be redesigned. The flameproof enclosure for the inverter system disclosed in this disclosure uses Creo's 3D finite element analysis and associative design. By 3D solidifying the flameproof enclosure and conducting finite element analysis, the structure is optimized. Under the premise of meeting the flameproof requirements, the design can be completed quickly and efficiently, and the drawings can be output. Therefore, the design software used is Creo 2.0, and the finite element analysis software is ANSYS. After the core structure size is confirmed, the inner cavity size of the explosion-proof shell can be obtained; according to the design requirements, the installation method is to push in horizontally from one side of the shell, so a full-through door needs to be opened on the left side of the explosion-proof shell, and a guide rail needs to be set under the inner wall, and it needs to be extended; there is also a requirement to place the whole body against the wall at the use site, so three inspection doors are set on the front side of the shell; after the basic structure is determined, the shell structure is roughly designed for finite element analysis and optimization to determine the shell wall thickness, flange thickness and width, and reinforcement rib thickness, height and layout.

[0062] Specifically, the explosion-proof enclosure used for the frequency converter system may include a detailed design, with high-voltage wiring cavities arranged on the left and right sides for the incoming and outgoing lines and flange surfaces reserved for the installation of cable connectors; an observation window and an operating keyboard are arranged on the corresponding maintenance door on the right side of the front operation and display part of the frequency converter core; a wiring cavity is set up on the right side of the corresponding core part that needs to be wired; the non-power lines such as control, display, door locking switch and signal acquisition are included in the intrinsically safe circuit through the isolation fence; a docking device with an explosion-proof surface is designed at the position corresponding to the water-cooling pipe flange; a lifting device will be used during production and transportation, and the corresponding lifting holes are designed; flatbed trucks or rail transportation can be used for underground transportation and installation, and the installation holes and wheelset installation positions are designed.

[0063] Those skilled in the art will appreciate that the present invention is not limited to the embodiments described above, and that the present invention may be implemented in many other forms without departing from its spirit and scope. Therefore, the examples and embodiments shown are to be considered illustrative rather than restrictive, and that the present invention may encompass various modifications and substitutions without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. A high-voltage inverter system, comprising a first filter unit, a rectifier feedback unit, a DC bus unit, an inverter unit, a second filter unit and a controller unit, and configured to be connected between an input voltage terminal and a motor unit, characterized in that: The first filtering unit is connected between the input voltage terminal and the rectifying feedback unit, comprises a filter and a common mode reactor and is configured so that the input voltage is adjusted to meet the voltage compliance standard of the rectifying feedback unit; The rectification feedback unit is connected between the first filtering unit and the DC bus unit, includes a bridge circuit composed of an IGBT-based active front-end inverter and is configured to perform conversion between an AC voltage signal and a DC voltage signal; The DC bus unit is connected between the rectification and feedback unit and the inverter unit, includes a braking capacitor and a braking resistor, and is configured to absorb the electric energy that cannot be fed to the motor in the electric state and feed back the absorbed electric energy on the DC bus unit via the rectification and feedback unit; The inverter unit is connected between the DC bus unit and the second filter unit, includes a bridge circuit composed of an IGBT-based active front-end inverter and is configured to perform conversion between an AC voltage signal and a DC voltage signal; The second filtering unit is connected between the inverter unit and the motor unit, includes a DV / DT filter and is configured to receive an AC voltage signal from the inverter unit and adjust the received AC voltage signal to meet a voltage compliance standard of the motor unit; and The controller unit is connected to the first filter unit, the rectifier feedback unit, the DC bus unit, the inverter unit, and the second filter unit, and is configured to determine the working state of the motor and control the first filter unit, the rectifier feedback unit, the inverter unit, and the second filter unit to perform high-voltage frequency conversion.

2. The high voltage inverter system according to claim 1, characterized in that: Controlling the first filter unit, the rectification feedback unit, the inverter unit, and the second filter unit to perform high-voltage frequency conversion includes: In response to determining that the working state of the motor is the motoring state, the controller is configured to control the rectification and feedback unit to receive the AC voltage signal and convert the AC voltage signal into a DC voltage signal and feed it to the inverter unit via the DC bus unit, and further control the inverter unit to receive the DC voltage signal from the DC bus unit and invert the DC voltage signal into an AC voltage signal with adjustable voltage and frequency and feed it to the motor, thereby controlling the AC motor to work; and In response to determining that the working state of the motor is the power generation state, the controller is configured to control the inverter unit to receive the AC voltage signal generated by the motor and convert the AC voltage signal into a DC voltage signal and feed the DC voltage signal to the rectification and feedback unit via the DC bus unit, and also control the rectification and feedback unit to invert the DC voltage signal into a sinusoidal AC voltage signal that is synchronized with the power grid and in the same phase as the power grid and feed the AC voltage signal to the power grid after the first filter unit filters out high-order harmonics.

3. The high voltage inverter system according to claim 1, characterized in that: The conversion or inversion of the DC voltage signal and the AC voltage signal by the rectifier feedback unit and the inverter unit is realized by triggering a bridge circuit composed of an active front-end inverter of the IGBT of the rectifier feedback unit and the inverter unit based on a predetermined trigger timing.

4. The high-voltage inverter system according to any one of claims 1 to 3, further comprising a cooling subsystem, characterized in that: The cooling subsystem includes a main circulation module, a deionized water module and a water replenishment module.

5. The high voltage inverter system according to claim 4, characterized in that: The main circulation module is configured to provide power for the deionized water side circulation operation and to measure the pressure, temperature, flow rate and conductivity of the deionized water side operation.

6. The high voltage inverter system according to claim 4, characterized in that: The deionized water module is configured to dynamically remove electrolyte ions dissolved in the deionized water, thereby ensuring that the conductivity of the deionized water side of the cooling system meets the operating requirements of the frequency conversion device.

7. The high voltage inverter system according to claim 4, characterized in that: The cooling subsystem also includes a water-to-water heat dissipation module, which is configured to dissipate the heat on the deionized water side into external water in a continuous and stable manner.

8. The high voltage inverter system according to claim 4, characterized in that: The cooling subsystem also includes a water-air heat dissipation module, which is configured to dissipate the heat on the deionized water side into the air continuously and stably.

9. The high voltage inverter system according to claim 4, characterized in that: The water replenishment module is configured to add a corresponding volume of replenishment water to the deionized water side of the cooling system based on a predetermined instruction.

10. The high voltage inverter system according to claim 1, characterized in that: The high-voltage inverter system also includes an explosion-proof housing, wherein the inner cavity size, installation method, wall thickness, flange thickness and width, and rib thickness, height and arrangement of the explosion-proof housing are determined based on finite element analysis and the size of the high-voltage inverter system. The installation method includes pushing one side of the housing in horizontally, a full-through door is opened on one side of the explosion-proof housing, an extendable guide rail is arranged under the inner wall of the explosion-proof housing, and a plurality of inspection doors are arranged in front of the explosion-proof housing.

11. The high voltage inverter system according to claim 1, characterized in that: The controller unit monitors the motor according to a machine learning algorithm to determine the operating status of the motor.

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