Magnetic levitation micro gas turbine power plant and control method thereof

Abstract

The application discloses a magnetic suspension micro gas turbine power station and a control method thereof, and belongs to the technical field of micro gas turbine power generation. The magnetic suspension micro gas turbine power station comprises a micro gas turbine, a magnetic suspension motor and an electronic control system. The micro gas turbine is one of a type without a regenerator, a type with a built-in regenerator or a type with an external regenerator. The air inlet of the centrifugal compressor of the micro gas turbine is arranged in the magnetic suspension motor, and the motor stator is fixed in the air inlet. The centrifugal compressor and the radial turbine are back-to-back arranged on the rotating shaft, the radial turbine is fixed on the cantilever end of the rotating shaft and located outside the two radial magnetic bearings to form cantilever support, and the centrifugal compressor, the radial turbine, the motor rotor and the magnetic bearing rotor adopt a coaxial mounting structure. The application also adopts a double cooling gas path and a three-ring nested control strategy, and realizes high integration, oil-free, efficient cooling and precise dynamic control of the power station.

Description

Technical Field

[0001] This application belongs to the field of micro gas turbine power generation technology, specifically relating to a magnetically levitated micro gas turbine power station and its control method. Background Technology

[0002] Micro gas turbine power plants are compact energy supply devices that use natural gas, diesel, kerosene, etc. as fuel. They have advantages such as high power density, wide fuel adaptability, low emissions, and low noise, and have broad applications in distributed power generation, emergency power supply, vehicle range extenders, communication base stations, and data center energy supply.

[0003] Existing micro gas turbine power plants typically suffer from the following shortcomings: Firstly, regarding structural layout, traditional units often employ a separate layout of "gas turbine, speed-increasing gearbox, and high-speed generator," resulting in a large overall size, high mechanical losses, and high noise levels. Some designs use couplings to connect the gas turbine rotor and the generator rotor, but this separate structure increases axial length and rotational inertia, reducing system reliability. Furthermore, the rotor system relies on oil-lubricated rolling or sliding bearings, requiring complex lubrication circuits and cooling systems, leading to high maintenance costs and difficulty in rapid start-up and reliable operation in extreme environments such as high altitudes and frigid zones.

[0004] Secondly, regarding motor cooling. High-speed permanent magnet motors have high power density and generate a lot of heat. In existing technologies, some solutions use independent cooling jackets and coolants for cooling, which increases the system complexity and weight; other solutions place the motor at the front end of the compressor, but the motor is still an independent unit and does not make full use of the intake air for efficient cooling.

[0005] Secondly, regarding bearing support, the existing magnetic levitation bearing layout fails to fully utilize the compressor intake cooling bearing coils and lacks a comprehensive redundancy and failure protection mechanism.

[0006] Finally, regarding control strategies, micro gas turbines are highly nonlinear and multivariable systems. Existing control strategies are mostly decoupled speed closed-loop control or simple temperature open-loop control, which are prone to overshoot, surge, or even stalling when faced with dynamic conditions such as sudden load increases or decreases. Furthermore, control accuracy will significantly decrease as engine performance deteriorates after prolonged use.

[0007] Therefore, there is an urgent need for a micro gas turbine power plant solution that is more compact, has more efficient cooling, is easier to maintain, has more precise control, and has a more stable dynamic response. Summary of the Invention

[0008] This invention proposes a magnetically levitated micro gas turbine power station, aiming to solve the problems of non-compact structure, poor motor heat dissipation, high maintenance costs due to reliance on oil lubrication system, and poor dynamic control accuracy and insufficiency in existing micro gas turbine power stations.

[0009] The technical solution is as follows: On one hand, a magnetically levitated micro gas turbine power station is characterized by comprising: A micro gas turbine, which is one of the following: without a regenerator, with an internal regenerator, or with an external regenerator; it includes: a centrifugal compressor, a combustion chamber, and a radial turbine, wherein the centrifugal compressor has an air intake; Magnetic levitation generator, including: Shaft; A permanent magnet motor has a motor rotor fixedly mounted on the rotating shaft and a motor stator; The magnetic levitation bearing system includes a bearing housing and two radial magnetic bearings and one axial magnetic bearing mounted on the bearing housing. The two radial magnetic bearings and one axial magnetic bearing are all fitted onto the rotating shaft to achieve five-degree-of-freedom active control of the rotating shaft. This fully magnetically levitation oil-free support structure completely replaces traditional oil-lubricated bearings, eliminating the need for lubrication lines and cooling systems, achieving maintenance-free, low-noise, and highly reliable operation.

[0010] An electronic control system is connected to the micro gas turbine and the magnetic levitation generator respectively, and is used to perform multivariable integrated control. The centrifugal compressor's air intake duct is integrated within the magnetic levitation generator, and the motor stator is fixedly mounted within the air intake duct. This arrangement ensures that the compressor's intake air flows through the motor stator before entering the impeller, achieving a high degree of structural integration.

[0011] The centrifugal compressor and the radial turbine are mounted back-to-back on the rotating shaft. The two radial magnetic bearings are located inside the motor section of the rotating shaft. The impeller of the radial turbine is fixedly mounted on the cantilever end of the rotating shaft, located outside the two radial magnetic bearings, forming a cantilever support. The centrifugal compressor, the radial turbine, the rotating shaft, and the magnetic bearing rotor are coaxially mounted. This structure eliminates the need for a gearbox and coupling, achieving integrated direct drive of the gas turbine and generator, significantly shortening the axial dimension, and improving mechanical efficiency and power density.

[0012] Furthermore, the micro gas turbine also has an engine housing, the magnetic levitation generator is fixed to the inner wall of the intake casing of the engine housing, and the bearing seat is fixed to the motor stator housing.

[0013] Furthermore, when the micro gas turbine is in the external regenerator mode, it also includes an external regenerator, which is connected to the outlet of the centrifugal compressor and the inlet of the combustion chamber via pipelines.

[0014] Furthermore, when the micro gas turbine is in the mode of having a built-in regenerator, it also includes an annular regenerator. The combustion chamber is fixed inside the annular regenerator, and an annular toothed disc is provided inside the annular regenerator to isolate the compartment where the centrifugal compressor is located from the compartment where the centrifugal turbine is located.

[0015] Furthermore, it also includes a cooling air path, which utilizes the intake air of the centrifugal compressor to cool the permanent magnet motor. The cooling air path includes: a main air path, formed by an annular channel between the motor stator housing and the inner wall of the intake duct; and an auxiliary air path, formed by the air gap between the motor stator and the rotating shaft. The main air path and the auxiliary air path merge before entering the impeller of the centrifugal compressor. This design solves the heat dissipation problem of high-power-density motors, recovers heat lost from motor losses, preheats the intake air, and improves the overall thermal efficiency of the machine.

[0016] Furthermore, it also includes a fuel supply system for supplying fuel to the combustion chamber, which includes: a fuel controller, a fuel circuit actuator, and a combustion-supporting circuit actuator; The fuel controller is used to control the fuel circuit actuator and the combustion-supporting circuit actuator to adjust the ratio of fuel flow to gas delivered to the combustion chamber.

[0017] Furthermore, the electronic control system adopts a three-loop nested control strategy, including: The power loop (outer loop) generates a speed signal based on the difference between the load power requirement and the actual generated power. The speed loop (middle loop) generates control parameters based on the difference between the speed signal and the actual speed; The combustion temperature ring (inner ring) takes the combined input of the engine speed signal and the exhaust temperature signal, calculates the energy value through an incremental proportional-integral algorithm, and controls the fuel flow rate based on the energy value.

[0018] This composite control strategy avoids the oscillation problem caused by the coupling between the traditional dual closed loop of speed and temperature. At the same time, when engine performance deteriorates, temperature feedback can promptly correct the fuel supply to prevent stalling and surge.

[0019] Furthermore, it also includes a brake control system that executes two braking modes: In the event of a grid-side fault, disconnect the grid-connected circuit breaker, activate the braking circuit, and convert the shaft kinetic energy into DC bus electrical energy and charge the battery through a bidirectional energy converter. In the event of a non-grid-side fault, the grid-connected circuit breaker is disconnected, causing the permanent magnet motor to enter coasting power generation mode. When the speed drops below the threshold, the braking circuit is automatically engaged.

[0020] Furthermore, the magnetic levitation bearing system is also equipped with redundancy and failure protection mechanisms, including: dual-winding coils, temperature monitoring devices, and protective bearings to buffer the shaft from falling in the event of power failure or malfunction.

[0021] On the other hand, a control method for a magnetically levitated micro gas turbine power plant is provided, applied to the aforementioned magnetically levitated micro gas turbine power plant, comprising the following steps: The electronic control system performs multivariable integrated control, employing a three-loop nested control strategy. Power loop control: Generates a speed signal based on the difference between the load power requirement and the actual generated power; Speed ​​loop control: Generate control parameters based on the difference between the speed signal and the actual speed; Temperature loop control: The speed signal and exhaust temperature signal are fed back together and the energy value is obtained by incremental proportional-integral algorithm. The fuel flow rate delivered to the combustion chamber is controlled according to the energy value.

[0022] The technical solution includes at least the following technical effects: 1. By incorporating the air intake and stator into the layout, the axial dimension is significantly reduced, eliminating the need for gearboxes and couplings, thereby improving power density and mechanical efficiency.

[0023] 2. By using a dual cooling air path, the heat dissipation problem of the high-speed motor is efficiently solved, and heat is recovered to preheat the intake air, thereby improving the overall thermal efficiency of the machine.

[0024] 3. Fully magnetically levitated and oil-free support eliminates the need for lubrication circuits, achieving maintenance-free, low-noise, and highly reliable operation, making it especially suitable for extreme environments such as high-altitude and cold regions.

[0025] 3. The three-loop nested control strategy, combined with incremental PI control based on speed-temperature composite feedback, significantly improves dynamic response speed and stability, effectively preventing stalling and surge.

[0026] 4. The dual-mode braking control intelligently switches according to the type of fault, realizing energy recovery while avoiding mechanical impact, thus improving system safety.

[0027] 5. The multi-variable integrated electronic control system simplifies the system architecture and improves the reliability and coordination of the overall machine control. Attached Figure Description

[0028] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0029] Figure 1 A schematic diagram of a magnetically levitated micro gas turbine power plant is provided as a preferred embodiment of this application; Figure 2 A schematic diagram of a fuel supply system provided in a preferred embodiment of this application; Figure 3 A schematic diagram of the structure of a micro gas turbine and a magnetic levitation generator in a magnetic levitation micro gas turbine power plant, provided as a preferred embodiment of this application; Figure 4 A schematic diagram of a micro gas turbine with a built-in regenerator provided in a preferred embodiment of this application; Figure 5 for Figure 4 Enlarged view of point A in the middle; Figure 6 The gas flow process inside a micro gas turbine with a built-in regenerator is provided in a preferred embodiment of this application.

[0030] Explanation of reference numerals in the attached figures: 1. Magnetic levitation generator; 101. Axial magnetic bearing; 102. Radial magnetic bearing; 103. Motor stator; 104. Motor stator housing; 105. Intake casing; 106. Motor rotor; 107. Intake duct; 2. Gas turbine; 201. Centrifugal compressor; 202. Annular grate disc; 203. Exhaust port; 204. Annular regenerator; 205. Centripetal turbine; 206. Combustion chamber; 207. Regenerator low-temperature high-pressure inlet; 208. Regenerator high-temperature high-pressure exhaust port; 209. Grate mounting hole; 210. Engine housing; 211. Countersunk screw hole; 212. Combustion chamber housing; 213. Rear compartment housing; 214. Rear compartment mounting cover; 215. Impeller fastening screw; 216. Front compartment housing. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0032] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0033] This application provides a magnetic levitation micro gas turbine power station, comprising: a micro gas turbine, a magnetic levitation generator, an electronic control system (ECU), a rectifier control module, a battery management and control module, a battery pack, a magnetic bearing control module, a fuel control module, a gas pump control module, a DC-DC controller, an inverter grid connection module, and an emergency braking control system. Compared with traditional power stations, this application eliminates equipment such as oil bearings, gearboxes, and lubrication stations, achieving oil-free operation. It features a high power-to-weight ratio, high efficiency, high comprehensive energy utilization efficiency, clean emissions, low noise, long lifespan, and multi-fuel compatibility, making it a highly valuable next-generation distributed energy equipment in the field of military-civilian integration.

[0034] A micro gas turbine, which is one of the following: without a regenerator, with an internal regenerator, or with an external regenerator; it includes: a centrifugal compressor, a combustion chamber, and a radial turbine, wherein the centrifugal compressor has an air intake; Magnetic levitation generator, including: Shaft; The permanent magnet motor has a motor rotor 106 fixedly mounted on the rotating shaft and a motor stator 103. The magnetic levitation bearing system includes a bearing housing and two radial magnetic bearings and one axial magnetic bearing mounted on the bearing housing. The two radial magnetic bearings and one axial magnetic bearing are all sleeved on the rotating shaft to achieve five-degree-of-freedom active control of the rotating shaft.

[0035] The electronic control unit (ECU) is connected to both the micro gas turbine and the magnetic levitation generator, and is used to perform multivariable integrated control. This application employs multivariable system integrated control technology, integrating combustion control, motor control, magnetic bearing control, grid connection control, battery charging and discharging control, and braking control into the ECU, thereby improving the overall control reliability.

[0036] Regarding the control strategy, this application employs a three-loop control system: an outer power loop, a middle speed loop, and an inner combustion temperature loop. The magnetic levitation micro-turbine power station uses an incremental PI control algorithm. In the inner closed-loop control algorithm, the speed or exhaust temperature signal is fed back to the ECU control system. The ECU control system then calculates the energy value and controls the fuel flow.

[0037] The centrifugal compressor's air intake duct is built inside the magnetic levitation generator, and the motor stator is fixedly installed inside the air intake duct. The impeller of the centrifugal compressor and the impeller of the radial turbine are fixed to the same end of the rotating shaft, and the two are arranged with their backs facing each other. The two radial magnetic bearings are located inside the motor section of the rotating shaft, and the impeller of the centripetal turbine is fixedly mounted on the cantilever end of the rotating shaft and located outside the two radial magnetic bearings, forming a cantilever support. The centrifugal compressor 201, the centrifugal turbine 205, the rotating shaft, and the magnetic bearing rotor adopt a coaxial mounting structure.

[0038] according to Figure 1 The schematic diagram of the magnetic levitation micro gas turbine power station shown below illustrates its working principle as follows: A micro gas turbine drives a magnetic levitation generator to rotate, converting the chemical energy of fuel into electrical energy. The generator's output AC power is converted to 760V DC power by a rectifier control module and fed into a 760V DC bus as the energy center of the entire station. This bus supplies power to the inverter grid-connected module, the DC-DC controller, and the battery management and control module: the inverter grid-connected module inverts the 760V DC power into 400V / 230V / 50Hz three-phase four-wire AC power, providing AC power to external loads, enabling grid connection or independent power supply; the DC-DC controller steps down the 760V DC power to 216V DC power to supply the secondary bus, which further outputs 28.5V DC power through DC-DC conversion (used for magnetic bearing control, fuel control, gas circuit control, etc.); the battery management and control module connects to the battery pack to realize battery charging and discharging management, used for system startup, peak power compensation, and emergency backup power. Meanwhile, the Electronic Control Unit (ECU), as the core control unit of the entire power station, connects via a communication bus to the magnetic bearing control module, fuel control module, air pump control module, rectifier control module, battery management and control module, inverter grid-connection module, and DC-DC controller, respectively, to perform multi-variable integrated control: the magnetic bearing control module controls two radial magnetic bearings and one axial magnetic bearing to achieve five-degree-of-freedom active suspension control of the shaft; the fuel control module regulates the fuel flow to the combustion chamber; the air pump control module regulates the combustion gas flow to ensure the optimal fuel-air ratio; the rectifier control module achieves voltage stabilization and rectification of the generator output power; the battery management and control module monitors the battery status and controls the charging and discharging process; the inverter grid-connection module achieves grid synchronization, power regulation, and islanding protection; and the DC-DC controller maintains voltage stability on each stage of the DC bus. Furthermore, the ECU also connects to remote interfaces and monitoring interfaces, supporting remote monitoring, parameter configuration, fault diagnosis, and operating status display, enabling intelligent management of the power station. This application achieves unified energy dispatch through a 760V DC bus and coordinated control of various subsystems through an ECU controller, eliminating the complex gear transmission and oil lubrication system of traditional power plants, and significantly improving the power density, reliability and comprehensive energy utilization of the system.

[0039] The fuel control module is part of the fuel supply system.

[0040] according to Figure 2 The schematic diagram of the fuel supply system shown in this application illustrates the working principle of the fuel supply system provided in this application as follows: The fuel supply system consists of a fuel controller, a fuel circuit actuator, and a combustion-supporting circuit actuator. The fuel controller controls the fuel circuit actuator and the combustion-supporting circuit actuator to work together based on the energy value Q calculated by the electronic control unit (ECU) to provide the optimal fuel-air ratio for the gas turbine combustion chamber.

[0041] Working principle of the fuel system actuator: Fuel flows in from an external fuel source, is filtered by a fuel filter, and then enters the booster pump, which increases the fuel pressure to a set value. A pressure regulator maintains stable fuel system pressure. The electronic fuel pump, under the control of the fuel controller, adjusts the fuel delivery according to engine operating conditions. Fuel is distributed via a fuel distributor; one path injects fuel into the combustion chamber during startup through the start-up injection valve, while the other path supplies fuel through the main fuel line. A fuel system pressure sensor monitors the fuel system pressure in real time and feeds it back to the fuel controller, achieving closed-loop regulation. When the system stops or pressure needs to be released, the drain valve opens, draining fuel from the pipeline to the return tank. A drain pump is used to discharge and recover fuel from the return tank. The fuel controller also receives signals from a level sensor to monitor the return tank level. The entire fuel system is connected to the fuel controller via a cable for signal transmission and actuation.

[0042] Working principle of the combustion-supporting air circuit actuator: The air pump draws in air from the atmosphere and compresses it. The compressed air is divided into two paths by an air splitter: one path, after being regulated by the air-supporting air flow valve, is sent to the combustion chamber as combustion air; the other path, after being regulated by the air circuit terminal valve, is used for other pneumatic components (such as air circuit sealing or cooling). The air circuit pressure sensor monitors the combustion-supporting air circuit pressure and feeds it back to the fuel controller to precisely adjust the opening of the air-supporting air flow valve, ensuring the optimal air-fuel ratio under different operating conditions.

[0043] Coordinated control process: When the engine starts, the fuel controller controls the opening of the starter fuel injection valve, the electronic fuel pump supplies fuel, and the air pump starts simultaneously, with the air-fuel ratio valve opening according to the starting air-fuel ratio. After successful ignition, the fuel controller adjusts the fuel supply of the electronic fuel pump and the opening of the air-fuel ratio valve in real time based on the energy value Q sent by the ECU, maintaining the optimal ratio of fuel flow to combustion air flow for efficient and clean combustion. When the engine stops or malfunctions, the fuel controller shuts off the electronic fuel pump, opens the drain valve to cut off the fuel supply, and simultaneously closes the air-fuel ratio valve to ensure safety.

[0044] The fuel supply system achieves precise adjustment of the fuel-gas ratio over a wide operating range through the coordinated control of the fuel circuit and the gas circuit by the fuel controller, ensuring the efficient and stable operation of the gas turbine.

[0045] like Figures 3-5 As shown, this application provides a magnetic levitation micro gas turbine power station, the core of which lies in the highly integrated design of the micro gas turbine and the magnetic levitation generator. The key integrated structure is reflected in: First, the air intake duct 107 is integrated into the stator. The air intake duct 107 of the centrifugal compressor 201 is integrated inside the magnetic levitation generator 1, and the motor stator 104 is fixedly installed inside the air intake duct 107. This allows the compressor intake air to flow through the motor stator 104 before entering the impeller, achieving efficient cooling.

[0046] Second, a dual cooling air path. The cooling air path utilizes the low-temperature intake air from the centrifugal compressor 201 to cool the permanent magnet motor. The low-temperature intake air is divided into two paths: the main air path is formed by the annular channel between the motor stator housing and the inner wall of the intake passage 107; the auxiliary air path is formed by the air gap between the motor stator housing 104 and the shaft. The main and auxiliary air paths merge before entering the impeller of the centrifugal compressor 201. Both airflows are ultimately drawn into the compressor, which not only efficiently solves the motor heat dissipation problem but also recovers heat to preheat the intake air, improving the utilization rate of the intake air temperature.

[0047] Third, a back-to-back cantilever direct-drive structure. The impellers of the centrifugal compressor 201 and the radial turbine 205 are fixed to the same end of the shaft, with their backs facing each other. Two radial magnetic bearings 102 are located inside the motor section of the shaft, and the impeller of the radial turbine 205 is fixedly mounted on the cantilever end of the shaft, located outside the two radial magnetic bearings 102, forming a cantilever support. The centrifugal compressor 201, radial turbine 305, shaft, and magnetic bearing rotor are coaxially mounted. This design eliminates the need for a gearbox and coupling, significantly reducing the axial dimension.

[0048] Fourth, redundant protection for magnetic bearings. The magnetic levitation bearing system is equipped with redundancy and failure protection mechanisms, including dual-winding coils, a temperature monitoring device, and a protective bearing to buffer rotor drop in the event of power failure or malfunction. The magnetic bearing body uses a high-permeability iron core and high-performance rare-earth permanent magnet materials (such as neodymium iron boron) to enhance load-bearing capacity. Air cooling is introduced to solve the problem of electromagnetic coil overheating, ensuring long-term operational stability. The magnetic bearing sensor control achieves micron-level precision, and a derating design is implemented between the system bandwidth and shaft speed.

[0049] Fifth, the fuel supply system. The fuel supply system includes a fuel controller, fuel line actuators, and combustion-supporting fuel line actuators, used to supply fuel to the combustion chamber 206. The fuel controller controls the fuel line actuators and combustion-supporting fuel line actuators to work together based on the energy value calculated by the electronic control unit (ECU) to provide the optimal air-fuel ratio for combustion in the gas turbine combustion chamber 206.

[0050] Sixth, Coaxial Rotor System: The micro gas turbine engine 2 consists of a centrifugal compressor 201, a combustion chamber 206, a radial turbine 205, a magnetic levitation motor, etc. The rotor system (motor rotor 106, magnetic bearing rotor, centrifugal compressor 201, radial turbine 205, and all other rotor components) adopts a coaxial mounting structure. The centrifugal compressor 201 and the radial turbine 205 are mounted back-to-back on the motor rotor 106. The motor rotor 106 is supported by two magnetic levitation bearings using a 1-1-0 structure. The stator of the motor is mounted on the intake duct 107 of the centrifugal compressor 201. In one embodiment, the combustion chamber 206 is a return-type annular combustion chamber.

[0051] This application incorporates both installation structure design and online dynamic balancing design in its design to ensure coaxial assembly and high-speed rotation of the rotor system.

[0052] The engine housing includes a front compartment housing 216, a rear compartment housing 213, and a rear compartment mounting cover 214. The combustion chamber 206 assembly and the annular regenerator 204 assembly are mounted on the rear compartment housing 213, and the annular grates are mounted on the combustion chamber 206.

[0053] During assembly, the radial turbine 205, annular grating, and centrifugal compressor 201 pass back-to-back through the guide shaft fixture and are installed into the rear housing 213 assembly. Then, the front housing 216 is fixed onto the rear housing 213 (point B in the figure). The magnetic bearing rotor is mounted on the rotating shaft, passes through the motor stator 104, and passes from the left side through the centrifugal compressor 201, annular grating, and radial turbine 205. The guide shaft fixture is pushed out from the rear housing mounting cover 214. Through the rear housing mounting cover 214, the impeller fastening screws 215 are installed, realizing the coaxial structure assembly of the rotor system.

[0054] Since the rotor system of the engine in this application rotates at high speed, the above-mentioned mounting structure cannot guarantee the dynamic imbalance of the rotor system. Therefore, in the design, online dynamic balancing measures are considered. Several small dynamic balancing screw holes are set on the impeller fastening screw 215. Through the rear housing mounting cover 214, the small dynamic balancing screws are added or removed to achieve precise online dynamic balancing and ensure that the rotor can rotate at high speed.

[0055] Example 1: Mode without Regenerator This embodiment provides a magnetically levitated micro gas turbine power plant. The micro gas turbine includes a centrifugal compressor, a combustion chamber, and a radial turbine. The centrifugal compressor has an air intake. In this embodiment, the micro gas turbine is in a regenerator-less mode, and the outlet of the centrifugal compressor is directly connected to the inlet of the combustion chamber.

[0056] A magnetic levitation generator comprises a shaft, a permanent magnet motor, and a magnetic levitation bearing system. The permanent magnet motor has a motor rotor (permanent magnet) fixedly mounted on the shaft, and a motor stator. The magnetic levitation bearing system includes a bearing housing, and two radial magnetic bearings and one axial magnetic bearing mounted on the bearing housing. The two radial magnetic bearings and one axial magnetic bearing are all fitted onto the shaft to achieve five degrees of freedom active control of the shaft.

[0057] The electronic control system (ECU) is connected to the micro gas turbine and the magnetic levitation generator respectively to perform multivariable integrated control.

[0058] Example 2: Built-in Regenerator Mode As attached Figures 3-5 As shown, this embodiment adds an annular regenerator 204 to the first embodiment; the annular regenerator design improves the combustion efficiency of the engine.

[0059] When the micro gas turbine 2 is in the built-in regenerator mode, an annular regenerator 204 is installed inside the micro gas turbine 2, and the combustion chamber 206 is fixed inside the annular regenerator 204. An annular toothed disc 202 is provided inside the annular regenerator 204 to isolate the compartment where the centrifugal compressor 201 is located from the compartment where the radial turbine 205 is located. The annular toothed disc 202 is installed on the combustion chamber shell through countersunk screw holes 211. A toothed mounting hole 209 is provided on the gas turbine 2 casing to fasten the countersunk screws on the annular toothed disc 202 to the combustion chamber shell, realizing the overall installation, that is, the compressor and the radial turbine 205 (cantilevered on the motor rotor 106 of the magnetic levitation generator 1) are integrally installed with the magnetic levitation generator 1 on the annular regenerator 204 and the combustion chamber 206.

[0060] In one embodiment, the engine combustion chamber 206 is fixed inside the annular regenerator 204. The annular regenerator 204 is provided with an annular toothed disc 202 to isolate the centrifugal compressor compartment (front compartment) and the radial turbine compartment (rear compartment). The annular toothed disc 202 is mounted on the combustion chamber housing through countersunk screw holes 211. For ease of installation, toothed disc mounting holes 209 are provided on the engine housing to fasten the countersunk screws on the annular toothed disc 202 to the combustion chamber housing.

[0061] The annular regenerator 204 exchanges heat between the low-temperature airflow at the outlet of the centrifugal compressor 201 and the high-temperature airflow at the outlet of the combustion chamber 206 within the shortest distance, thereby reducing the exhaust temperature of the engine and increasing the intake temperature at the inlet of the combustion chamber 206, thus significantly improving the combustion efficiency of the engine. In existing embodiments, the combustion efficiency of a micro engine without a regenerator is about 20%, while the efficiency of an engine with a regenerator can be increased by more than 10%.

[0062] When using an annular regenerator, the installation of the compressor and the high-pressure gas outlet structure of the compressor, the installation of the grate plate, the installation of the radial turbine, the structure of the combustion chamber intake, and the structure of the combustion exhaust gas inlet and outlet are taken into consideration to achieve the shortest gas path emission and efficient heat exchange, resulting in a compact structure and small size.

[0063] like Figure 6 As shown, air enters through the intake casing 105, and the high-pressure, low-temperature combustible gas compressed by the centrifugal compressor 201 enters the cold side of the regenerator through the low-temperature, high-pressure intake port 207. It absorbs the residual heat of the combustion exhaust gas for heating. The combustible gas after heat exchange enters the combustion chamber 206 through the high-temperature, high-pressure exhaust port 208 of the regenerator and mixes with the fuel for combustion. The high-temperature gas generated drives the centripetal turbine 205 to do work. The high-temperature combustion exhaust gas discharged from the centripetal turbine 205 passes through the hot side of the regenerator, releases heat to the combustible gas on the cold side, and then its temperature decreases. Finally, it is discharged from the exhaust port combustion exhaust gas outlet.

[0064] Example 3: External Regenerator Mode When the micro gas turbine is in external regenerator mode, the external regenerator is located outside the engine casing and connected to the outlet of the centrifugal compressor and the inlet of the combustion chamber via pipelines. The regenerator recovers exhaust waste heat and preheats the compressed air entering the combustion chamber, thereby improving thermal efficiency.

[0065] This application adopts an integrated control design: Integrated control includes: integrated control of motor, engine, and magnetic bearing; and integrated control of emergency braking and magnetic bearing emergency protection.

[0066] Based on the coaxial mounting structure of the rotor system, with the motor control speed as the reference, the engine combustion control and the motor control speed and power are coordinated to ensure power balance; the magnetic bearing coordinates the adaptive notch control speed of the rotor system with the motor control speed to ensure smooth speed control.

[0067] In the event of a grid-side fault, the braking circuit is activated, and a bidirectional energy converter is used to convert the motor's kinetic energy into DC bus power, ensuring power supply to the magnetic bearing control system and preventing the magnetic bearing from falling off.

[0068] In existing technologies, the engine and motor are connected in series. The engine has an oil-lubricated bearing structure, and the motor is a magnetic levitation motor. The rotor system of such products is a non-levitation rotor system, and the engine life and reliability are no different from ordinary engines. This application uses a magnetically levitation micro gas turbine and magnetically levitation bearings.

[0069] The difference between the existing hydrodynamic air suspension bearing and the magnetic suspension bearing of this application: The levitation force of a dynamic pressure air bearing comes from the air film generated during rotation, which is a passive airflow; the levitation force of a magnetic levitation bearing comes from electromagnetic force and can be actively controlled. Dynamic pressure air suspension bearings have low load-bearing capacity, while magnetic suspension bearings can have a very high load-bearing capacity. Dynamic air bearings do not require control, but friction occurs during start-up and shutdown, resulting in low reliability and short lifespan; magnetic bearings require control, are frictionless throughout the entire process, and have high reliability and long lifespan.

[0070] Example 4: Control Method for Magnetic Levitation Micro Gas Turbine Power Plant This embodiment provides a control method for a magnetically levitated micro gas turbine power plant, applied to the aforementioned magnetically levitated micro gas turbine power plant; including: The electronic control unit (ECU) performs multivariable integrated control, employing a three-loop nested control strategy: Power loop (outer loop): Generates speed signal based on the difference between the load power requirement and the actual generated power.

[0071] Speed ​​Loop (Middle Loop): Generates control parameters based on the difference between the speed signal and the actual speed.

[0072] Combustion temperature ring (inner ring): The combined input of the speed signal and the exhaust temperature signal is used to calculate the energy value through an incremental proportional-integral algorithm. The flow rate of fuel delivered to the combustion chamber is controlled according to the energy value to achieve speed adjustment.

[0073] The basic form of the incremental proportional-integral algorithm is: ; ; in, For sampling sequence number, For the first The computer output value at the next sampling time; For the first The increment of the control quantity at each sampling time; For the first The deviation value input at the next sampling time This is the proportionality coefficient. The integral coefficient; This refers to the exhaust temperature.

[0074] In this embodiment, the magnetic levitation micro-turbine power station adopts an incremental PI control algorithm. In the inner closed-loop control algorithm, the speed or exhaust temperature signal is fed back to the ECU control system. After calculation, the ECU control system obtains the energy value Q and then controls the fuel flow, that is: ; This control strategy avoids mutual interference between the two closed-loop circuits in a simple dual-loop system, and improves control accuracy, reduces the impact of engine performance degradation on acceleration and power generation, thus effectively improving engine efficiency.

[0075] In the formula, For sampling sequence number, The deviation value input at the k-th sampling time. This is the proportionality coefficient. The integral coefficient. The proportional coefficient. It is directly related to the deviation value of each sampling, therefore improving... This enables the system to respond quickly, while the integral coefficient... Related to all the previous sampling deviation values, the function of the integral term is to reduce the steady-state error. Since the sampling period is long, the error of each sampling has a large impact. Therefore, reducing the integral coefficient is beneficial to improving the control accuracy.

[0076] Example 5: Braking Control Method This embodiment provides two braking modes.

[0077] In the event of a grid-side fault (such as a power outage): The electronic control system (ECU) disconnects the grid-connected circuit breaker, activates the braking circuit, and converts the shaft kinetic energy into DC bus electrical energy via a bidirectional energy converter, charging the battery. The braking torque is adjusted proportionally to the square of the rotational speed to ensure smooth braking.

[0078] Specifically, a five-prevention interlocking mechanism (to prevent misoperation) is used to achieve safe tripping; the starting braking circuit uses a bidirectional energy converter to convert the motor's kinetic energy into DC bus electrical energy, and the braking torque is adjusted according to the square of the speed; battery charging control allows charging only when SOC < 90%, the charging current is limited to 50% of the rated value, and a constant current followed by constant voltage mode is adopted to prevent overcharging; motor mode switching: the inverter switches from grid-connected mode to energy consumption braking mode, and the braking current is controlled by adjusting the PWM duty cycle.

[0079] In the event of a non-grid-side fault (such as an internal generator fault): the electronic control system (ECU) disconnects the grid-connected circuit breaker, causing the permanent magnet motor to enter coasting power generation mode. When the speed drops below the threshold, the braking circuit is automatically engaged.

[0080] Specifically, the fault handling on the same grid side involves: putting the permanent magnet motor into coasting generation mode, switching the inverter to low power output mode (output power < 20% of rated power), and maintaining the DC bus voltage stability by adjusting the excitation current; and preparing the braking circuit: the braking circuit is pre-charged to 80% of the rated voltage and automatically engaged when the speed drops below 30% to complete the final braking.

[0081] This staged braking strategy avoids the huge impact on the mechanical structure caused by direct energy dissipation braking at high speeds.

[0082] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

Claims

1. A magnetically levitated micro gas turbine power station, characterized in that, include: A micro gas turbine is one of the following: without a regenerator, with an internal regenerator, or with an external regenerator. It includes: a centrifugal compressor, a combustion chamber, and a radial turbine, wherein the centrifugal compressor has an air intake; Magnetic levitation generator, including: Shaft; A permanent magnet motor has a motor rotor fixedly mounted on the rotating shaft and a motor stator; A magnetic levitation bearing system includes a bearing housing, and two radial magnetic bearings and one axial magnetic bearing disposed on the bearing housing. The two radial magnetic bearings and one axial magnetic bearing are all sleeved on the rotating shaft to realize five-degree-of-freedom active control of the rotating shaft. An electronic control system is connected to the micro gas turbine and the magnetic levitation generator respectively, and is used to perform multivariable integrated control. The centrifugal compressor's air intake duct is built inside the magnetic levitation generator, and the motor stator is fixedly installed inside the air intake duct. The centrifugal compressor and the centrifugal turbine are mounted back-to-back on the rotating shaft; The two radial magnetic bearings are located inside the motor section of the rotating shaft, and the impeller of the centripetal turbine is fixedly installed on the cantilever end of the rotating shaft and located outside the two radial magnetic bearings, forming a cantilever support. The centrifugal compressor, centripetal turbine, motor rotor, and magnetic bearing rotor are coaxially mounted.

2. The magnetic levitation micro gas turbine power station according to claim 1, characterized in that, The micro gas turbine also has an engine housing, the magnetic levitation generator is fixed to the inner wall of the intake casing of the engine housing, and the bearing seat is fixed to the motor stator housing.

3. The magnetic levitation micro gas turbine power plant according to claim 2, characterized in that, When the micro gas turbine is in the external regenerator mode, it also includes an external regenerator, which is connected to the outlet of the centrifugal compressor and the inlet of the combustion chamber via pipelines.

4. The magnetic levitation micro gas turbine power station according to claim 1, characterized in that, When the micro gas turbine is in the mode of having a built-in regenerator, it also includes an annular regenerator. The combustion chamber is fixed inside the annular regenerator. The annular regenerator is provided with an annular toothed disc to isolate the compartment where the centrifugal compressor is located from the compartment where the centrifugal turbine is located.

5. The magnetic levitation micro gas turbine power station according to claim 1, characterized in that, It also includes a cooling air path, which utilizes the intake air of the centrifugal compressor to cool the permanent magnet motor; the cooling air path includes: The main air passage is formed by an annular channel between the motor stator housing and the inner wall of the intake duct. The auxiliary air passage is formed by the air gap between the motor stator and the rotating shaft; The main air passage and the auxiliary air passage merge before entering the impeller of the centrifugal compressor.

6. The magnetic levitation micro gas turbine power station according to claim 1, characterized in that, It also includes a fuel supply system, which comprises: Fuel controller; Fuel circuit actuators include: fuel controller, booster pump, exhaust pump, electronic fuel pump, and fuel circuit pressure sensor; The gas-supporting circuit actuator includes: an air pump, an air distributor, an air-supporting flow valve, and a gas circuit terminal valve; The fuel controller is used to control the fuel circuit actuator and the combustion-supporting circuit actuator to adjust the ratio of fuel flow to gas delivered to the combustion chamber.

7. The magnetic levitation micro gas turbine power plant according to claim 1, characterized in that, The electronic control system adopts a three-loop nested control strategy, including: The power loop generates a speed signal based on the difference between the load power requirement and the actual generated power. The speed loop generates control parameters based on the difference between the speed signal and the actual speed. The combustion temperature loop takes the combined input of the engine speed signal and the exhaust temperature signal, calculates the energy value through an incremental proportional-integral algorithm, and controls the fuel flow rate based on the energy value.

8. The magnetic levitation micro gas turbine power station according to claim 1, characterized in that, It also includes a brake control system, which is used to execute two braking modes: In the event of a grid-side fault, disconnect the grid-connected circuit breaker, activate the braking circuit, and convert the shaft kinetic energy into DC bus electrical energy and charge the battery through a bidirectional energy converter. In the event of a non-grid-side fault, the grid-connected circuit breaker is disconnected, causing the permanent magnet motor to enter coasting power generation mode. When the speed drops below the threshold, the braking circuit is automatically engaged.

9. The magnetic levitation micro gas turbine power station according to claim 1, characterized in that, The magnetic levitation bearing system is also equipped with redundancy and failure protection mechanisms, including: dual-winding coils, temperature monitoring devices, and protective bearings to buffer the shaft from falling in the event of power failure or malfunction.

10. A control method for a magnetically levitated micro gas turbine power plant, applied to the magnetically levitated micro gas turbine power plant as described in any one of claims 1 to 9, characterized in that, include: Multivariable integrated control is performed through an electronic control system, employing a three-loop nested control strategy. Power loop control: Generates a speed signal based on the difference between the load power requirement and the actual generated power; Speed ​​loop control: Generates control parameters based on the difference between the target speed command and the actual speed; Temperature loop control: The engine speed signal and the exhaust temperature signal are fed back together and the energy value is obtained by incremental proportional-integral algorithm. The fuel flow rate delivered to the combustion chamber is controlled according to the energy value.

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