Intelligent variable-frequency main air supply unit for city domain train and control method of intelligent variable-frequency main air supply unit

Abstract

The intelligent variable-frequency main air supply unit comprises a compressed air generation module, an air post-processing module, an electrical control module, a pressure control module and an intelligent variable-frequency control module, and is integrally supported on a cross beam at the bottom of the train through a hanging bracket; the compressed air generation module is an oil screw type air compressor and is connected with the air source hanging bracket, and the oil screw type air compressor comprises an air inlet filter, an air inlet valve, a screw machine head, an oil-gas separator, a temperature control valve, a cooling system and a permanent magnet synchronous motor. An absolute pressure sensor is integrated at the air inlet valve and is used for feeding back the air suction negative pressure state of the air filter in real time; the cooling system comprises a centrifugal impeller, a volute, a diffuser and a cooler, and temperature sensors are integrated at a cooling air inlet and an outlet of the cooler and used for monitoring the cooling air temperature of the unit and the temperature level of an outlet of a compressor in real time. A temperature sensor is integrated in the permanent magnet synchronous motor to monitor the temperature rise of a motor stator winding in real time.

Description

Technical Field

[0001] This invention relates to the field of rail vehicle braking equipment technology, and in particular to an intelligent variable frequency main air supply unit for urban rail trains and its control method. Background Technology

[0002] The construction of urban (suburban) railways is developing rapidly, and a series of urban trains with various speed levels have been formed, covering speeds from 140km / h to 160km / h, with a demand for speeds up to 200km / h. To accelerate construction and promote the integration of the four networks (railway, railway, and urban rail transit), and given the increasingly strong market demand for urban trains, it is urgent to develop a platform-based, simplified main air supply unit product that is compatible with a variety of train models, while reducing R&D costs, shortening the supply cycle, and coordinating full life-cycle management.

[0003] Existing main air supply units for urban rail transit braking systems generally suffer from the following problems: high instantaneous inrush current / noise during unit startup and excessive noise during continuous operation, affecting passenger comfort; due to fixed displacement, oil emulsification is prone to occur under special application conditions such as train commissioning, low operational rates, and hot and humid weather, leading to cumbersome operation and maintenance; replacement of easily damaged and consumable parts is carried out according to specific cycles, without linkage with actual unit operating time or environment for condition-based maintenance, resulting in insufficient or excessive maintenance; low unit integration, large size and weight, occupying significant space under the vehicle. Faced with the industry's trend towards intelligent and green development and the inherent requirements for improving vehicle quality, existing technologies are insufficient to meet the core requirements of the next generation of intelligent urban rail transit trains for low-noise, reliable, intelligent, and convenient maintenance of the air supply system. Therefore, it is necessary to provide a main air supply unit technical solution to address the above problems. Summary of the Invention

[0004] This invention addresses the interface requirements of urban train ventilation systems. Based on an oil-lubricated screw-type main air supply unit, it employs permanent magnet synchronous motor drive technology to achieve flexible unit startup, significantly reducing startup power load and eliminating inrush current and startup mechanical shock. Simultaneously, it utilizes variable frequency speed control technology, combined with the actual air consumption conditions of the vehicle, to achieve intelligent adjustment of the air supply operating mode and displacement, reducing operating noise, improving passenger comfort, and enabling rapid air replenishment under extreme air consumption conditions, thus enhancing vehicle air supply safety redundancy. Furthermore, it integrates PHM technology to achieve functions such as monitoring the status of key unit parameters, early warning of fault trends, and condition-based maintenance of key consumables, and features intelligent, platform-based, and integrated characteristics.

[0005] The objective of this invention is achieved through the following technical solutions.

[0006] A smart variable frequency main air supply unit for urban rail transit includes a compressed air generation module, an air post-treatment module, an electrical control module, a pressure control module, and a smart variable frequency control module, which are integrated into one unit by a hanger and mounted on the bottom crossbeam of the train.

[0007] The main air supply unit is equipped with a heat dissipation duct assembly, which can promptly discharge the cooled hot air from the air compressor cooler to the outside of the vehicle's equipment compartment (if applicable), improving the unit's weather resistance. The heat dissipation duct is connected to the main air supply unit bracket by bolts and sealed to the air compressor cooler by a duct sealing ring to prevent the cooling air from spreading to other areas. The duct sealing ring is made of rubber and has a buffer structure to isolate the compressor unit from vibration and impact during vehicle operation.

[0008] The compressed air generating module is mainly an oil-lubricated screw air compressor, connected to the air source bracket via rubber vibration dampers. The oil-lubricated screw air compressor mainly consists of an intake filter, intake valve, screw compressor head, oil-gas separator, temperature control valve, cooling system, permanent magnet synchronous motor, and related brackets and supports. An absolute pressure sensor is integrated at the intake valve for real-time feedback of the air filter's intake negative pressure. The cooling system consists of a centrifugal impeller, volute, diffuser, and cooler. Temperature sensors are integrated at both the cooling air inlet and the cooler outlet (i.e., the compressor outlet) for real-time monitoring of the unit's cooling air temperature (indirectly feeding back ambient temperature) and the compressor outlet temperature level. A temperature sensor is integrated inside the permanent magnet synchronous motor to monitor the temperature rise of the motor stator windings in real-time.

[0009] The post-treatment system consists of a pre-filter assembly, a dual-tower dryer, and an outlet filter. The pre-filter comprises an air-water separator, a condensate filter, a drain solenoid valve, a heater, a protective plate, and a drain block. Impurities filtered out by the filter are discharged through the integrated drain solenoid valve at the bottom in a set sequence, ensuring the quality of the air entering the dryer. A heater is installed at the valve body of the drain solenoid valve to prevent icing and jamming in low winter temperatures. A protective plate is installed at the bottom of the drain solenoid valve, and a drain block assembly is integrated on the plate. Impurities discharged from the drain solenoid valve are discharged through a hose and the drain block to the outside of the equipment compartment (if applicable). The dual-tower dryer adopts the working principle of "pressure swing adsorption, heatless regeneration" and mainly consists of drying towers, an integrated air circuit board, a reversing valve, and an electronic controller. The electronic controller integrates a control circuit board to control the switching sequence of the two drying towers. Two pressure sensors are installed on the integrated air circuit board of the dryer to monitor and provide feedback on the internal pressure values ​​of the two drying towers in real time. The reversing valve and integrated air circuit board are installed sideways, and the outlet is equipped with an exhaust muffler. It can be converted to be installed upwards via an adapter to minimize the space occupied by the undercarriage height limit. The outlet filter is located at the dryer outlet and adopts a high-precision deep pleated filter element manufacturing process to filter fine solid dust and ensure that the air quality of the main air supply unit meets the air requirements of the train (ISO 8573-1 2-2-2).

[0010] The electrical control module includes an electrical control box assembly and an electrical connector assembly. The electrical control box assembly adopts a box-type integrated design and is connected to the main air source hanger via bolts. It mainly consists of a protective box assembly, intermediate relays, time relays, and related wiring terminals. The protective box assembly is equipped with a secondary anti-detachment structure to avoid the risk of the box cover loosening due to human error. The electrical connector assembly includes a control connector (DC110V) and a power connector (AC380V), which are connected to the air source hanger via mounting brackets.

[0011] The pressure control module mainly consists of a minimum pressure valve at the air source outlet, a safety valve, an auxiliary pressure switch assembly, and a hanger. The hanger adopts a "Z-shaped" structure design, which improves the space utilization of the minimum pressure valve and the auxiliary pressure switch assembly, enabling convenient online maintenance of the minimum pressure valve. The auxiliary pressure switch assembly is equipped with a protective cover, enhancing the overall protection level.

[0012] The intelligent frequency converter control module is powered by AC380V and can be optionally equipped with DC600V input. It has the following main functions:

[0013] Data Acquisition and Communication: The frequency converter control module integrates RS485 / CAN / Ethernet communication, pressure detection, temperature detection and other functions. It can collect data from pressure switch, temperature switch, pressure sensor and temperature sensor in real time, and synchronously collect key parameters of motor and controller. The status information is uploaded to vehicle electronic control unit (BCU) through CAN communication.

[0014] Control execution: The frequency conversion control module can drive the permanent magnet synchronous motor into the set working mode (start, speed adjustment, shutdown, etc.) according to the control commands issued by the BCU, and synchronously feed back the working status of the main air supply unit to the BCU.

[0015] Fault protection mechanism: When the main air supply unit malfunctions, it immediately sends a fault code to the BCU via CAN and responds accordingly based on the BCU's instructions. If the controller detects serious faults such as output short circuit, bus overvoltage, or phase loss, it immediately shuts down for protection and reports the fault to the BCU via CAN.

[0016] The intelligent frequency converter control module mainly consists of a circuit board assembly, a cooling module, and a protective enclosure assembly. The circuit board assembly comprises five boards: an EMC board, a power board, a drive control board, a capacitor board, and a network board. These boards are stacked to maximize space utilization, improve product integration, and reduce the size and weight of the circuit board assembly. The capacitor boards are designed independently, avoiding the resource waste associated with replacing the entire board during maintenance in traditional integrated designs. The cooling module mainly consists of a plate-fin radiator, a cooling fan, and an air duct assembly. In high-speed urban vehicles with equipment compartments or high-altitude operations, natural convection cooling is weak. Forced convection cooling of the radiator requires adjusting the cooling fan based on the air temperature. The cooling fan is located at the bottom of the cooling module, and the cooling air blows upwards, aligning with the direction of hot air convection (hot air, being less dense, convects upwards), maximizing heat dissipation performance. Air outlets are located on the sides and top of the air duct assembly. The protective enclosure assembly includes the enclosure and related connectors, and the enclosure features a secondary anti-detachment structure.

[0017] A method for controlling the main air supply unit of an urban rail transit train is characterized in that the BCU sends a working mode signal based on the change in the total air pressure (MR) of the vehicle, and the intelligent frequency conversion control module receives the signal and controls the main air supply unit to operate according to the specified mode.

[0018] Furthermore, the intelligent variable frequency control module collects various operating data signals from the main air supply unit and transmits them to the ground PHM platform via the BCU to achieve real-time monitoring of the intelligent air compressor's status. Specific items include: CMK closing signal monitoring, suction negative pressure, cooling air temperature / compressor outlet temperature, dryer operating status, motor winding temperature rise, IGBT temperature, power supply abnormalities of the intelligent variable frequency control module, and lubricating oil temperature signal feedback.

[0019] The specific steps include:

[0020] 1) CMK closing signal monitoring: When the train's three-phase AC contactor CMK is closed, the main air supply unit works, the intelligent frequency conversion control module records the CMK closing status and synchronously feeds it back to the BCU, providing real-time feedback on the actual operating time of the unit, providing real operation and maintenance information feedback for maintenance work, and realizing condition-based maintenance by linking vulnerable and consumable parts with the actual operating time of the unit.

[0021] 2) Intake negative pressure monitoring: An absolute pressure sensor is installed at the rear end of the air filter element. The pressure signal is collected in real time through the intelligent frequency conversion control module to determine the status of the intake filter element. When the design threshold is exceeded, an early warning signal is fed back to the BCU, and the maintenance personnel replace the filter element in advance.

[0022] 3) Cooling air temperature / compressor outlet temperature monitoring: Temperature sensors are installed at the air intake of the cooler fan and the outlet of the compressor. The data is collected by the intelligent frequency converter control module to monitor the cooling air temperature T1 and the compressor outlet exhaust temperature T2 in real time. When the temperature T1 reaches the limit, the intelligent frequency converter controller starts the cooling fan to force heat dissipation. When T2-T1≥the set threshold, a high temperature warning is issued by the BCU.

[0023] 4) Dryer operation status monitoring: Pressure sensors PSL and PSR are configured on the integrated air circuit board of the dryer to monitor the pressure of the two drying towers respectively. When the air compressor starts, if the pressure of either tower exceeds or falls below the set value for t seconds, a status warning will be issued. If the pressure continues to exceed the set number of times, it will be judged as a dryer malfunction, the unit will be controlled to stop, and the information will be reported to the BCU.

[0024] 5) Motor winding temperature rise: The motor is equipped with a winding temperature rise sensor. The intelligent frequency conversion control module collects the winding temperature rise status in real time. When the temperature rise exceeds the design threshold, the generator unit stops and reports to the BCU.

[0025] 6) IGBT temperature monitoring: The intelligent frequency conversion control module circuit board assembly is equipped with IGBT over-temperature protection monitoring. When the IGBT temperature is too high, it will trigger a shutdown and report to the BCU.

[0026] 7) Intelligent variable frequency control module power supply monitoring: When a power supply failure occurs, the unit is triggered to shut down and the information is reported to the BCU;

[0027] 8) Oil temperature switch action signal: When the lubricating oil temperature is higher than the set upper limit temperature, the normally closed contact of the temperature switch integrated inside the machine head opens, the unit stops, and the normally open contact closes. The signal is collected and fed back to the BCU through the intelligent frequency conversion control module. When the oil temperature cools down, the normally closed contact of the temperature switch closes again, the high temperature alarm on the vehicle side is released, and the unit is ready to start.

[0028] Compared with the prior art, the advantages of this invention are:

[0029] (1) Permanent magnet synchronous motor drive technology is adopted to realize soft start of the main air supply unit, reducing instantaneous impact vibration and noise during startup;

[0030] (2) The BCU sends a working mode signal according to the MR change. The intelligent frequency conversion control module receives the signal and controls the main air supply unit to operate according to the specified mode, thereby realizing the speed control of the motor and finally realizing the flexible adjustment of the unit's displacement, reducing noise during operation, improving passenger comfort, and enabling rapid air replenishment under extreme air consumption conditions, thus improving the safety redundancy of vehicle air supply.

[0031] (3) It has remote monitoring and intelligent management functions, and can collect and analyze unit operation data in real time to realize intelligent fault early warning and operation and maintenance scheduling, thereby reducing unit failure rate and operation and maintenance costs;

[0032] (4) The design is miniaturized, simplified and platform-based, while taking into account the structural requirements of the vehicle equipment compartment of high-speed urban trains. The intelligent frequency conversion control module adopts an independent cooling system design to improve the overall weather resistance (high temperature and high altitude conditions) performance and expand the range of applicable models. Attached Figure Description

[0033] Figure 1 , Figure 2 This is a schematic diagram of the structure of an intelligent variable frequency main air supply unit for urban rail transit according to an embodiment of the present invention.

[0034] Figure 3 This is a schematic diagram of the heat dissipation duct assembly of the main air supply unit according to an embodiment of the present invention.

[0035] Figure 4 This is a schematic diagram of the air compressor assembly of the main air supply unit according to an embodiment of the present invention.

[0036] Figure 5 , Figure 6 This is a schematic diagram of the post-processing module structure of the main air supply unit according to an embodiment of the present invention.

[0037] Figure 7 This is a schematic diagram of the main air supply unit pressure control module according to an embodiment of the present invention.

[0038] Figure 8This is a schematic diagram of the intelligent frequency conversion control module of the main air supply unit according to an embodiment of the present invention.

[0039] Figure 9 , Figure 10 This is a block diagram illustrating the structure and principle of the circuit board assembly of the intelligent frequency conversion control module for the main air supply unit according to an embodiment of the present invention.

[0040] Figure 11 , Figure 12 This is an example of a control method for an intelligent variable frequency main air supply unit of a city-area train (including variable frequency control logic and PHM intelligent operation and maintenance control logic) according to an embodiment of the present invention.

[0041] In the diagram: 1-Hanger assembly; 2-Double tower dryer; 3-Electrical control module; 4-Heat dissipation duct assembly; 5-Rubber stack vibration damper; 6-Compressed air generation module; 7-Pre-filter assembly; 8-Pressure control module; 9-Drain block; 10-Outlet filter; 11-Intelligent frequency conversion control module; 12-Outlet hose; 13-Duct sealing ring; 14-Duct support; 15-Rivet nut; 16-Outlet flange; 17-Stud; 18-Pull rivet; 19-Fan hood assembly; 20-Duct Installation slot diagram; 21-Cross-section of air duct sealing ring; 22-Permanent magnet synchronous motor; 23-Cooler; 24-Diffuser; 25-Volume; 26-Pressure maintaining valve; 27-Oil-gas cylinder; 28-First safety valve; 29-Oil filter; 30-Temperature control valve; 31-Secondary oil return assembly; 32-Vacuum indicator; 33-Head unit; 34-Air filter; 35-Unloading solenoid valve; 36-Backup pressure switch; 37-Absolute pressure sensor; 38-Inlet hose; 39-Inlet valve; 40-First Temperature sensor; 41-Second temperature sensor; 42-Temperature sensor bracket; 43-Compressor hanger; 44-Filter bracket; 45-Gas-water separator; 46-Colour filter; 47-Drain solenoid valve; 48-Guard plate; 49-Drain block; 50-Pipe fitting; 51-PU hose; 52-Heater; 53-Drying tower; 54-Pressure sensor PSL / PSR; 55-Integrated gas circuit board; 56-Electrical controller; 57-Reversing valve; 58-Compression fitting; 5 9-Exhaust muffler; 60-Test socket; 61-Z-type bracket; 62-Auxiliary pressure switch; 63-Protective cover assembly; 64-Minimum pressure valve; 65-Second safety valve; 66-Pressure switch bend; 67-Connector; 68-Bellwall joint; 69-Casing assembly; 70-Secondary anti-detachment structure; 71-Plate-fin radiator; 72-Cooling fan; 73-Air duct assembly; 74-EMC board; 75-Power board; 76-Drive control board; 77-Network board; 78-Capacitor board. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0043] like Figure 1 and 2 As shown, a smart variable frequency main air supply unit for urban rail transit trains comprises a hanger assembly 1, a compressed air generation module 6, an air after-treatment module (pre-filter assembly 7, dual-tower dryer 2, outlet filter 10), an electrical control module 3, a pressure control module 8, and a smart variable frequency control module 11. The hanger assembly 1 is connected to the compressed air generation module 6 via a rubber stack vibration damper 5, serving to isolate and reduce vibration. The compressed air generation module 6 and the air after-treatment module are connected via an outlet hose 12. Considering that high-speed urban rail transit vehicles have equipment compartments, a cooling duct assembly 4 and a drain block 9 are designed to discharge cooling hot air and impurities filtered out by the filter to the outside of the equipment compartment, improving the unit's high-temperature resistance. The air source outlet is designed with an internal thread structure, allowing for the installation of a compression fitting for connection to the vehicle's main air duct.

[0044] like Figure 3 As shown, the heat dissipation duct assembly 4 mainly consists of a duct sealing ring 13, a duct support 14, an outlet flange 16, and a fan shroud assembly 19. To minimize product weight while maintaining product strength, the duct support 14 is made of carbon steel, while the fan shroud assembly 19 and the outlet flange 16 are made of aluminum alloy. To avoid deformation caused by thin plate welding, the fan shroud assembly 19 is connected to the duct support 14 by rivets and bolts, and the fan shroud assembly 19 is fixed to the outlet flange 16 by blind rivets. To facilitate connection between the vehicle equipment compartment and the heat dissipation duct outlet, a ring of mounting studs 17 is designed on the outlet flange 16. The duct sealing ring 13 is designed with a buffer structure 21 to isolate the vibration and impact of the compressor unit during vehicle operation.

[0045] like Figure 4As shown, when the compressed air generation module is working, the permanent magnet synchronous motor 22 drives the compressor head 33 to rotate, creating a negative pressure that draws outside air through the air filter 34, then through the intake hose 38 and intake valve 39 into the compressor head 33 for compression. The compressed high-temperature, high-pressure oil-gas-water mixture undergoes oil-gas separation through the oil-gas cylinder 27, then passes through the pressure maintaining valve 26 into the cooler 23 for cooling before being output to subsequent modules. The lubricating oil, after oil-gas separation, is filtered by the oil filter 29 and then flows back into the compressor head 33 through the return oil pipe. When the lubricating oil temperature exceeds a set threshold, the temperature control valve 30 opens, allowing the lubricating oil to enter the cooler 23 for cooling, and then, after being filtered by the oil filter 29, flows back into the compressor head 33 through the return oil pipe, completing the oil circuit circulation. An absolute pressure sensor 38 is installed at the intake valve 39 port to provide real-time feedback on the air filter element's suction negative pressure value, indirectly indicating the filter element's contamination status. A first temperature sensor 40 is installed at the cooler outlet to monitor the compressor outlet working fluid temperature in real time. The second temperature sensor 41 is installed near the cooling air intake area and is connected to the permanent magnet synchronous motor 22 via the temperature sensor bracket 42 to monitor the cooling air temperature in real time (indirectly providing feedback on the ambient temperature of the unit). The compressed air generation module is connected to the hanger assembly 1 via the compressor hanger 43.

[0046] like Figure 5 As shown, this is an embodiment of the pre-filter assembly 7. The pre-filter assembly 7 is connected to the hanger assembly 1 via the filter bracket 44. Compressed air, compressed and cooled by the compressed air generation module, enters the air-water separator 45 to remove liquid water and oil. It then enters the condensation filter 46 for further removal of oil, water, and solid particulate impurities. The filtered impurities are discharged to the outside of the vehicle's equipment compartment (if any) via the drain solenoid valve 47, PU hose 51, and drain block 49. The drain solenoid valve 47 is equipped with a heater 52 to prevent abnormalities such as freezing of liquid water inside the valve due to low temperatures. The drain block 49 is installed on the guard plate 48, and the position of the drain outlet of the drain block 49 can be adaptively adjusted by adjusting the structural dimensions of the guard plate.

[0047] like Figure 6As shown, the dual-tower dryer 2 mainly consists of a drying tower 53, an integrated air circuit board 55, a reversing valve 57, and an electronic controller 56. The electronic controller 56 integrates a control circuit board to control the switching sequence of the two drying towers 53. Two pressure sensors 54 are installed on the integrated air circuit board 55 to monitor and provide feedback on the internal pressure values ​​of the two drying towers in real time. The dryer outlet is located on the side of the integrated air circuit board 55, and a test socket 60 is installed on the outlet air line for testing the air quality at the dryer outlet and troubleshooting. The dryer inlet is installed on the upper part of the reversing valve 57 via a compression fitting 58. The reversing valve 57 is installed side-mounted to the integrated air circuit board 55. An exhaust muffler 59 is installed at the drain port of the reversing valve, which is converted to an upward-facing installation via an adapter, improving product integration and reducing the occupancy of the vehicle's under-height limit dimensions.

[0048] like Figure 7 As shown, the pressure control module 8 mainly consists of a minimum pressure valve 64 at the air source outlet, a second safety valve 65, an auxiliary pressure switch 62, and a Z-shaped bracket 61. The auxiliary pressure switch 62 is equipped with a protective cover 63 to enhance the overall protection level. Pressure is collected from the air source outlet air path via a pressure switch bend 66. Simultaneously, the second safety valve 65 in the outlet air path monitors the total air pressure, providing overpressure protection. The minimum pressure valve 64 at the air source outlet can accumulate pressure during unit startup, ensuring the establishment of the switching pressure for the dual-tower dryer reversing valve 57.

[0049] like Figure 8 As shown, the intelligent frequency conversion control module 11 mainly consists of a protective enclosure assembly 69, a connector 67, a bellows joint 68, and a cooling module. The circuit board assembly is integrated inside the protective enclosure assembly 69, and interacts with the permanent magnet synchronous motor 22 and the electrical control module 3 through the connector 67 and the bellows joint 68. The protective enclosure is equipped with a secondary anti-detachment structure 70. The cooling module mainly consists of a plate-fin heat exchanger 71, a cooling fan 72, and an air duct assembly 73. When operating in high-speed urban vehicles with equipment compartments or at high altitudes, the natural convection cooling capacity is weak. It is necessary to judge and activate the cooling fan in a timely manner according to the cooling air temperature to force convection cooling of the radiator. The cooling fan 72 is located at the bottom of the cooling module, and the cooling air blows from bottom to top, which is consistent with the direction of hot air convection (hot air has a lower density and heats from bottom to top), thus maximizing the heat dissipation performance. The air duct assembly 73 has air outlets on the side and top.

[0050] like Figure 9 , Figure 10As shown, the circuit board assembly mainly consists of five boards: an EMC board 74, a power board 75, a drive control board 76, a network board 77, and a capacitor board 78. The boards adopt a stacked design to maximize space utilization, improve product integration, and reduce the size and weight of the circuit board assembly. The boards are electrically connected via copper busbars, which improves reliability compared to flying wire connections. After the AC380V / DC600V power supply is input, it first passes through the EMC board 74 to suppress high-frequency interference from the grid side using common-mode inductors and differential-mode capacitors. An LC filter is added at the inverter output to reduce high-frequency pulse voltage at the motor end and reduce cable radiation interference. Varistors are used to absorb voltage spikes and surge currents during IGBT switching, reducing high-frequency noise. A metal shielding layer is installed inside the boards to isolate high-frequency signals, and interference current is discharged through low-impedance grounding to ensure the intelligent frequency conversion control module can operate safely even in the presence of electromagnetic interference, preventing malfunctions or accidents caused by electromagnetic interference. The capacitor board 78 smooths and filters the bus voltage when the IGBT switches on and off, reducing voltage fluctuations and interference to other equipment. The board's independent design avoids the resource waste associated with replacing the entire board during maintenance, a common practice in traditional integrated designs. The power board 75 converts AC power to DC power via a three-phase bridge rectifier. After DC filtering and voltage smoothing, the DC power is inverted into AC power with adjustable frequency and voltage via pulse modulation technology using IGBT power devices, driving the permanent magnet synchronous motor 22 for variable frequency operation. The network board 77 parses the control commands sent by the BCU via CAN, extracts the valid parameters (operating mode), and transmits them to the drive control board 76. Simultaneously, it collects real-time parameters from various sensors (temperature, pressure), key parameters of the intelligent variable frequency control module (output current, bus voltage, IGBT temperature, etc.), and motor parameters (speed, temperature, etc.), encapsulates them according to the protocol, and uploads them back to the BCU. The network board uses CAN and Ethernet for communication, with a reserved RS485 communication interface for debugging. The drive control board 76 mainly controls the turn-on and turn-off timing of the IGBTs based on the instructions from the network board, and outputs variable frequency AC power.

[0051] like Figure 11As shown in the figure, a control method for an intelligent variable-frequency main air supply unit of a suburban train is characterized in that the BCU sends a working mode signal according to the change of the total vehicle air pressure (MR), and the intelligent variable-frequency control module receives and controls the operation of the main air supply unit according to the specified mode. Mode switching logic: The BCU selects the working mode according to the falling edge of MR, and maintains the state until shutdown according to the rising edge. When the MR pressure drops to X1 kPa, the BCU sends a start command for the "silent mode", and the main air supply unit adopts a reduced speed working mode; in the initial charging air condition or when the rising rate of the total air pressure < X2 kPa / min, the BCU sends a "fast charging air mode" command and switches to the increased speed air supply mode; when the communication of the intelligent variable-frequency control module is abnormal or during the menu-guided braking test, it works in the "standard air supply mode" (rated speed).

[0052] Further, as Figure 12 shown, the intelligent variable-frequency control module collects the operation data signals of the main air supply unit and transmits them to the ground PHM platform through the BCU to realize the real-time monitoring of the state of the intelligent air compressor, as follows:

[0053] 1) Monitoring of the CMK closing signal: When the three-phase AC contactor CMK of the train closes, the main air supply unit works. The intelligent variable-frequency control module records the closing state of CMK and synchronously feeds it back to the BCU, and the actual operation time of the unit is fed back in real time, providing real operation and maintenance information feedback for the maintenance work, realizing the linkage of vulnerable parts and the actual operation time of the unit to achieve condition-based maintenance, and avoiding the situation of insufficient or excessive maintenance.

[0054] 2) Monitoring of the suction negative pressure: An absolute pressure sensor is set at the rear end of the air filter element. The pressure signal is collected in real time through the intelligent variable-frequency control module to judge the state of the intake air filter element. When it exceeds the design threshold, a warning signal is fed back to the BCU, and the maintenance personnel can replace the filter element in advance according to the specific maintenance process to avoid abnormal problems such as the reduction of air supply efficiency caused by the expiration of the air filter life.

[0055] 3) Monitoring of the cooling air temperature / compressor outlet temperature: Temperature sensors are arranged at the suction port of the cooler cooling fan and the compressor outlet end. Through the intelligent variable-frequency control module, the cooling air temperature T1 / compressor outlet exhaust temperature T2 are monitored in real time. When the T1 temperature reaches the limit, the cooling fan of the intelligent variable-frequency controller is controlled to start forced cooling. When T2 - T1 ≥ the set threshold, a high-temperature warning is reported to the BCU.

[0056] 4) Monitoring of the dryer operation state: Pressure sensors PSL and PSR are configured on the integrated air circuit board of the dryer to monitor the pressures of the two drying towers respectively. When the air compressor starts and the pressure of any tower exceeds or is lower than the set value for t seconds, a state warning is given. When it continuously exceeds the set number of times, it is judged that the dryer fails, the unit is controlled to stop, and it is reported to the BCU.

[0057] 5) Motor winding temperature rise: The motor is equipped with a winding temperature rise sensor. The intelligent frequency conversion control module collects the winding temperature rise status in real time. When the temperature rise exceeds the design threshold, the generator unit stops and reports to the BCU.

[0058] 6) IGBT temperature monitoring: The intelligent frequency conversion control module circuit board assembly is equipped with IGBT over-temperature protection monitoring. When the IGBT temperature is too high, it will trigger a shutdown and report to the BCU.

[0059] 7) Intelligent frequency converter control module power supply monitoring: When a power supply fault occurs (overload, overvoltage, undervoltage, short circuit, etc.), the unit is triggered to stop and the information is reported to the BCU;

[0060] 8) Oil temperature switch action signal: When the lubricating oil temperature is higher than the set upper limit temperature, the normally closed contact of the temperature switch integrated inside the machine head opens, the unit stops, and the normally open contact closes. The signal is collected and fed back to the BCU through the intelligent frequency conversion control module. When the oil temperature cools down, the normally closed contact of the temperature switch closes again, the high temperature alarm on the vehicle side is released, and the unit is ready to start.

Claims

1. A smart variable frequency main air supply unit for urban rail transit, characterized in that... The system includes a compressed air generation module, an air after-treatment module, an electrical control module, a pressure control module, and an intelligent frequency conversion control module. The intelligent frequency conversion control module includes a circuit board assembly, a cooling module, and a protective enclosure assembly. The circuit board assembly includes an EMC board, a power board, a drive control board, a capacitor board, and a network board, all of which are stacked. The cooling module includes a plate-fin heat sink, a cooling fan, and an air duct assembly. The cooling fan is located at the bottom of the cooling module, and the cooling air blows upwards from the heat sink in the same direction as the hot air convection. The air duct assembly has air outlets on its sides and top. The protective enclosure assembly includes a protective enclosure and related connectors, and the protective enclosure has a secondary anti-detachment structure.

2. The intelligent variable frequency main air supply unit for urban rail transit according to claim 1, characterized in that... The compressed air generation module, air after-treatment module, electrical control module, pressure control module, and intelligent frequency conversion control module are integrated into one unit via a hanger and mounted on the bottom crossbeam of the train. The compressed air generation module is an oil-lubricated screw air compressor, connected to the air source hanger via rubber vibration dampers. The oil-lubricated screw air compressor includes an intake filter, intake valve, screw compressor head, oil-gas separator, temperature control valve, cooling system, and permanent magnet synchronous motor. An absolute pressure sensor is integrated at the intake valve for real-time feedback of the air filter intake negative pressure status. The cooling system includes a centrifugal impeller, volute, diffuser, and cooler. A temperature sensor is integrated at both the cooling air inlet and the cooler outlet for real-time monitoring of the unit's cooling air temperature and the compressor outlet temperature level. A temperature sensor is integrated inside the permanent magnet synchronous motor to monitor the temperature rise of the motor stator windings in real time.

3. The intelligent variable frequency main air supply unit for urban rail transit according to claim 1, characterized in that... The intelligent frequency conversion control module is powered by AC380V or DC600V input. It is used for data acquisition and communication: real-time acquisition of data from pressure switches, temperature switches, pressure sensors, and temperature sensors; synchronous acquisition of motor and controller parameters; and uploading status information to the vehicle electronic control unit via CAN communication. The intelligent frequency conversion control module is also used for control execution: based on control commands issued by the BCU, it drives the permanent magnet synchronous motor into a set operating mode and synchronously feeds back the main air supply unit's operating status to the BCU. Furthermore, the intelligent frequency conversion control module is used for fault protection: when a fault occurs in the main air supply unit, it immediately sends a fault code to the BCU via CAN and responds according to the BCU's commands. If the controller detects an output short circuit, bus overvoltage, or phase loss fault, it immediately shuts down for protection and reports the fault to the BCU via CAN.

4. The intelligent variable frequency main air supply unit for urban rail transit according to claim 1, characterized in that... The system includes a cooling duct assembly that promptly discharges the cooled hot air from the air compressor cooler to the outside of the vehicle. The cooling duct is connected to the main air supply unit hanger by bolts and sealed to the air compressor cooler by a duct sealing ring. The duct sealing ring is made of rubber and has a buffer structure designed to isolate the compressor unit from vibration and impact during vehicle operation.

5. The intelligent variable frequency main air supply unit for urban rail transit according to claim 1, characterized in that... The air aftertreatment module includes a pre-filter assembly, a dual-tower dryer, and an outlet filter. The pre-filter includes an air-water separator, a condensate filter, a drain solenoid valve, a heater, a protective plate, and a drain block. Impurities filtered out by the filter are discharged through the integrated drain solenoid valve at the bottom in a set sequence. A heater is installed at the valve body of the drain solenoid valve, and a protective plate is installed at the bottom of the drain solenoid valve. The protective plate integrates a drain block assembly. The drain assembly discharges the impurities discharged by the drain solenoid valve through a hose and the drain block to the outside. The dual-tower dryer includes a drying tower, an integrated air circuit board, a reversing valve, and an electronic controller. The electronic controller integrates a control circuit board to control the switching sequence of the two drying towers. Two pressure sensors are installed on the integrated air circuit board of the dryer to monitor and provide feedback on the internal pressure values ​​of the two drying towers in real time. The reversing valve is installed laterally with the integrated air circuit board, and an exhaust silencer is installed at the outlet. It can be converted to an upward installation through an adapter. The outlet filter is located at the dryer outlet and adopts a high-precision deep-folded filter element manufacturing process to filter fine solid dust.

6. The intelligent variable frequency main air supply unit for urban rail transit according to claim 1, characterized in that... The electrical control module includes an electrical control box assembly and an electrical connector assembly. The electrical control box assembly adopts a box-type integrated design and is connected to the main air source hanger by bolts. It includes a protective box assembly, intermediate relays, time relays, and related wiring terminals. The protective box assembly is equipped with a secondary anti-detachment structure. The electrical connector assembly includes a control electrical connector and a power electrical connector, and is connected to the air source hanger by a mounting bracket.

7. The intelligent variable frequency main air supply unit for urban rail transit according to claim 1, characterized in that... The pressure control module includes a minimum pressure valve at the air source outlet, a safety valve, an auxiliary pressure switch assembly, and a hanger. The hanger adopts a Z-shaped structure design, and the auxiliary pressure switch assembly is equipped with a protective cover assembly.

8. A control method for an intelligent variable frequency main air supply unit of a city-regional train, characterized in that... Using the intelligent variable frequency main air supply unit for urban trains as described in any one of claims 1-7, the BCU sends a working mode signal based on the change in the total air pressure of the vehicle. The intelligent variable frequency control module receives the signal and controls the operation of the main air supply unit according to the specified mode. The intelligent variable frequency control module collects various operating data signals of the main air supply unit and transmits them to the ground PHM platform via the BCU to realize real-time monitoring of the status of the intelligent air compressor. The specific points are: CMK closing signal monitoring, suction negative pressure, cooling air temperature / compressor outlet temperature, dryer operating status, motor winding temperature rise, IGBT temperature, power supply abnormality of the intelligent variable frequency control module, and lubricating oil temperature signal feedback.

9. A control method for an intelligent variable frequency main air supply unit of a city-area train according to claim 8, characterized in that... The specific steps include: 1) CMK closing signal monitoring: When the train's three-phase AC contactor CMK is closed, the main air supply unit works, the intelligent frequency conversion control module records the CMK closing status and synchronously feeds it back to the BCU, providing real-time feedback on the actual operating time of the unit, providing real operation and maintenance information feedback for maintenance work, and realizing condition-based maintenance by linking vulnerable and consumable parts with the actual operating time of the unit. 2) Intake negative pressure monitoring: An absolute pressure sensor is installed at the rear end of the air filter element. The pressure signal is collected in real time through the intelligent frequency conversion control module to determine the status of the intake filter element. When the design threshold is exceeded, an early warning signal is fed back to the BCU, and the maintenance personnel replace the filter element in advance. 3) Cooling air temperature / compressor outlet temperature monitoring: Temperature sensors are installed at the air intake of the cooler fan and the outlet of the compressor. The data is collected by the intelligent frequency converter control module to monitor the cooling air temperature T1 and the compressor outlet exhaust temperature T2 in real time. When the temperature T1 reaches the limit, the intelligent frequency converter controller starts the cooling fan to force heat dissipation. When T2-T1≥the set threshold, a high temperature warning is issued by the BCU. 4) Dryer operation status monitoring: Pressure sensors PSL and PSR are configured on the integrated air circuit board of the dryer to monitor the pressure of the two drying towers respectively. When the air compressor starts, if the pressure of either tower exceeds or falls below the set value for t seconds, a status warning will be issued. If the pressure continues to exceed the set number of times, it will be judged as a dryer malfunction, the unit will be controlled to stop, and the information will be reported to the BCU. 5) Motor winding temperature rise: The motor is equipped with a winding temperature rise sensor. The intelligent frequency conversion control module collects the winding temperature rise status in real time. When the temperature rise exceeds the design threshold, the generator unit stops and reports to the BCU. 6) IGBT temperature monitoring: The intelligent frequency conversion control module circuit board assembly is equipped with IGBT over-temperature protection monitoring. When the IGBT temperature is too high, it will trigger a shutdown and report to the BCU. 7) Intelligent variable frequency control module power supply monitoring: When a power supply failure occurs, the unit is triggered to shut down and the information is reported to the BCU; 8) Oil temperature switch action signal: When the lubricating oil temperature is higher than the set upper limit temperature, the normally closed contact of the temperature switch integrated inside the machine head opens, the unit stops, and the normally open contact closes. The signal is collected and fed back to the BCU through the intelligent frequency conversion control module. When the oil temperature cools down, the normally closed contact of the temperature switch closes again, the high temperature alarm on the vehicle side is released, and the unit is ready to start.

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