An air compressor system with self-heating for ice melting

Abstract

The present invention provides an air compressor system with self-heating ice melting, belonging to the technical field of fuel cells, and solves the problems in the prior art that the use of a heating water jacket and a PTC heating tape results in a complex structure, increased cost, and cumbersome control of the air compressor. The system includes an air compressor and a controller. Among them, the air compressor includes a housing and a permanent magnet synchronous motor, a compressor, and a turboexpander located inside the housing. The housing, the impeller of the compressor, the turbine of the turboexpander, and the volute are all prepared by using ferromagnetic materials or covering a ferromagnetic material coating on the surface of non-ferromagnetic materials. One end of the rotating shaft of the permanent magnet synchronous motor is installed with a compressor, and the other end is installed with a turboexpander. The controller is used to identify the presence of low-temperature icing inside the air compressor when the air compressor starts, and then control the quadrature-axis current of the motor I q = 0, and the direct-axis current I d is an alternating current with a set frequency and amplitude to perform eddy current heating and hysteresis loss heating on the air compressor until the ice melting is completed, and then start the air compressor normally.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and particularly to an air compressor system with self-heating and ice melting. Background Art

[0002] With the application in large vehicles such as heavy trucks, the power of fuel cell systems is increasing, resulting in an increasing power consumption of air compressors. The tail gas of high-power fuel cell systems has high energy, including kinetic energy and thermal energy. Recovering the energy of the tail gas of the fuel cell system through an air compressor with an expander can effectively reduce the power consumption of the air compressor, and thus improve the comprehensive energy utilization efficiency of the fuel cell system. However, the tail gas usually contains a large amount of liquid water and water vapor. When starting in low temperature, the liquid water remaining in the expansion end of the air compressor will freeze, resulting in the jamming of the turbine and the volute, making the air compressor unable to start normally.

[0003] There are two existing methods to solve the above-mentioned ice formation problem at the expansion end of the air compressor. The first method is to add a water jacket on the surface of the volute and heat the turbine volute by heating the water in the water jacket before starting in cold conditions. However, since the structure of the air compressor body becomes more complex after adding the water jacket, the cost increases, and at the same time, the thermal management architecture of the fuel cell system also becomes complex. The second method is to install a PTC heating tape on the outer surface of the volute or other positions to heat the turbine volute through the PTC heating tape. However, after installing the PTC heating tape, the structure of the air compressor body is also complicated, and the electrical architecture of the fuel cell system becomes complex, and the cost increases at the same time. Summary of the Invention

[0004] In view of the above analysis, the embodiments of the present invention aim to provide an air compressor system with self-heating and ice melting to solve the problems of inconvenient carrying, replacement, and poor safety of existing test fixtures.

[0005] On the one hand, the embodiments of the present invention provide an air compressor system with self-heating and ice melting, including an air compressor and a controller; wherein, the air compressor further includes a housing and a permanent magnet synchronous motor, a compressor, and a turbine expander located inside the housing; the housing, the impeller of the compressor, the turbine of the turbine expander, and the volute are all made of ferromagnetic materials or prepared by covering a ferromagnetic material coating on the surface of non-ferromagnetic materials;

[0006] One end of the rotating shaft of the permanent magnet synchronous motor is installed with a compressor, and the other end is installed with a turbine expander; the recovery gas inlet of the turbine expander is connected to the tail gas outlet of the fuel cell stack;

[0007] The controller is used to identify whether there is a low-temperature ice formation phenomenon inside the air compressor when the air compressor starts; and if so, control the quadrature-axis current I q = 0, and the direct-axis current I dAn alternating current with a set frequency and a set amplitude is used to perform eddy current heating and hysteresis loss heating on the air compressor until it is recognized that the low-temperature icing phenomenon has been eliminated, and then the air compressor is started normally.

[0008] The beneficial effects of the above technical solution are as follows: The method of eddy current heating and hysteresis loss heating is used to solve the icing problem at the expansion end of the air compressor during low-temperature cold start. Specifically, when the housing, impeller, turbine, and volute of the air compressor are made of ferromagnetic materials or a ferromagnetic material coating is covered on the surface of non-ferromagnetic materials, the alternating magnetic field generated by the permanent magnet synchronous motor will cause the ferromagnetic materials to be repeatedly magnetized while realizing eddy current heating, and the magnetic domains will continuously rub against each other to generate heat, that is, the temperatures of the components such as the housing, impeller, turbine, and volute of the air compressor will increase, thereby realizing the ice melting function.

[0009] Based on the further improvement of the above system, the controller further includes:

[0010] A data acquisition unit, which is used to acquire the ambient temperature of the air compressor system in real time and send it to the data processing and control unit;

[0011] A data processing and control unit, which is used to judge whether there is a low-temperature icing phenomenon inside the air compressor according to the received ambient temperature when the air compressor starts; if so, control the quadrature axis current I q = 0, and at the same time, the direct axis current I d is an alternating current with a set frequency and a set amplitude, which is used to perform eddy current heating and hysteresis loss heating on the air compressor, and identify whether the low-temperature icing phenomenon inside the air compressor is eliminated during the heating process. After the elimination, the air compressor is started normally;

[0012] The data acquisition unit further includes:

[0013] An ambient temperature sensor, which is arranged in the external environment of the air compressor and is used to acquire the ambient temperature at the installation position as the ambient temperature of the air compressor system;

[0014] An infrared temperature sensor, which is arranged on the inner wall of the intake pipeline of the turbine expander and is used to acquire the ambient temperature at the installation position as the internal temperature of the turbine expander; The data processing and control unit executes the following program:

[0015] Identify whether an air compressor start signal sent by the fuel cell system controller is received; if so, execute the next step;

[0016] Acquire the ambient temperature of the air compressor at the current moment, and judge whether there is a low-temperature icing phenomenon inside the air compressor; if so, execute the next step, otherwise, start the air compressor normally;

[0017] Control the quadrature axis current I q= 0, and at the same time, control the direct-axis current I d is an alternating current with a set frequency and set amplitude, and is used to perform eddy current heating and hysteresis loss heating on the air compressor;

[0018] Based on the ambient temperature of the air compressor system and the internal temperature of the turboexpander at the current moment, obtain the heating time t. Until after reaching the heating time t, it is determined that the low-temperature icing phenomenon inside the air compressor has been eliminated, and then adjust the direct-axis current I of the permanent magnet synchronous motor d = 0, and then start the air compressor normally.

[0019] The heating time t is determined by the following formula:

[0020] t = a(T2 - T1) 3 + b(T2 - T1) 2 + c(T2 - T1)+ dT2 + e

[0021] In the formula, T2 is the ambient temperature of the air compressor system, T1 is the internal temperature of the turboexpander, and a, b, c, d, e are coefficients calibrated according to the heating time for eliminating the low-temperature icing phenomenon in the laboratory;

[0022] This system further includes a flow control valve; the output port of the compressor is connected to the air inlet of the fuel cell stack through this flow control valve; and,

[0023] The turbine of the turboexpander and the impeller of the compressor are respectively installed at both ends of the rotating shaft of the permanent magnet synchronous motor; the data acquisition unit further includes:

[0024] An impeller speed and torque monitoring sub-unit, which is used to monitor the speed and torque of the impeller in the compressor and send them to the data processing and control unit; and,

[0025] The data processing and control unit also executes the following program:

[0026] Start the air compressor and obtain the speed and torque of the impeller in the compressor;

[0027] Identify whether it meets the condition that the speed of the impeller in the compressor remains zero continuously within a preset time period and the torque of the compressor is higher than the set torque. If so, it is determined that there is a low-temperature icing phenomenon inside the air compressor; otherwise, it is determined that there is no low-temperature icing phenomenon inside the air compressor.

[0028] Furthermore, the data acquisition unit further includes:

[0029] A gas temperature-flow integrated sensor, which is arranged at the air inlet of the turboexpander and is used to obtain the gas temperature and flow rate at the installation position; and,

[0030] The data processing and control unit also executes the following program:

[0031] After the air compressor is started, according to the gas temperature and flow rate collected by the gas temperature-flow integrated sensor, the direct-axis current I of the permanent magnet synchronous motor d is synchronously adjusted in terms of amplitude and frequency.

[0032] Furthermore, the rotating shaft is supported at both ends of the permanent magnet synchronous motor by high-speed rolling bearings or high-speed sliding bearings; and,

[0033] A flow distribution valve is provided between the recovered gas inlet of the turboexpander and the exhaust port of the fuel cell.

[0034] Furthermore, the heating time t is the shortest heating time required to heat the volute to achieve the ice melting effect at this ambient temperature.

[0035] Compared with the prior art, the present invention can at least achieve one of the following beneficial effects:

[0036] 1. When the air compressor is cold-started, it does not rotate first. The quadrature-axis current I of the permanent magnet synchronous motor is controlled to be 0, and the direct-axis current I q is an alternating current with a set frequency and a set amplitude to perform eddy current heating on the air compressor for a set heating time. After the ice melting is completed, the air compressor is started normally. d 2. The ice in the internal gas pipeline of the air compressor is melted by heating methods based on two principles: eddy current heating and hysteresis loss heating. The heating effect is good and the ice melting speed is fast.

[0037] 3. It avoids the problems of complex structure, increased cost, and cumbersome control of the air compressor caused by using a heating water jacket and a PTC heating tape.

[0038] 4. Adding an air filter can improve the service life of the air compressor. Adding a flow distribution valve can adjust the flow rate of the exhaust gas entering the turboexpander according to requirements.

[0039] 5. The present invention provides the content of the invention to introduce the selection of concepts in a simplified form, which will be further described in the specific embodiments below. The content of the invention is not intended to identify the important features or essential features of the present disclosure, nor is it intended to limit the scope of the present disclosure.

[0040] BRIEF DESCRIPTION OF THE DRAWINGS BRIEF DESCRIPTION OF THE DRAWINGS

[0041] By describing the exemplary embodiments of the present disclosure in more detail in conjunction with the accompanying drawings, the above and other objects, features, and advantages of the present disclosure will become more apparent. Among them, in the exemplary embodiments of the present disclosure, the same reference numerals generally represent the same components.

[0042] Figure 1 FIG. 1 shows a schematic diagram of the composition of the self-heating and ice-melting air compressor system according to Embodiment 1;

[0043] Figure 2 Shows the schematic diagram of direct-axis current and quadrature-axis current control of the permanent magnet synchronous motor in Embodiment 1;

[0044] Figure 3 Shows the schematic diagram of partial control principle of the air compressor system with self-heating ice melting in Embodiment 2.

[0045] Reference numerals:

[0046] N - Geomagnetic North Pole; S - Geomagnetic South Pole; D-axis direction - Direct-axis current direction;

[0047] Q-axis direction - Quadrature-axis current direction; Is - Control current. Detailed implementation manners

[0048] The embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0049] The term "including" and its variants used herein mean open inclusion, that is, "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "at least partially based on". The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc. may refer to different or the same objects. There may also be other explicit and implicit definitions below.

[0050] To more clearly illustrate the technical effects of the present invention, the basic physical principles involved are first introduced.

[0051] The air compressor is driven by a permanent magnet synchronous motor, and when the stator winding of the motor passes through a changing current (direct-axis current), a changing magnetic field can be generated. According to the law of electromagnetic induction, when the magnetic field of the stator winding changes, any conductor in the magnetic field will generate an induced electromotive force and an induced current, and cause a circulating current. These circulating currents flow in a vortex shape around the magnetic field inside the conductor, which is called eddy current. Eddy current can heat the conductor. The higher the frequency of the magnetic flux change in the conductor, the greater the magnetic flux density B, the greater the induced electromotive force, the greater the eddy current, and the greater the power of eddy current heating, that is, the faster the temperature rise rate.

[0052] Ferromagnetic materials can be magnetized by an external magnetic field because there are many smaller natural magnetization regions called magnetic domains inside them. When a ferromagnetic material component is placed in an alternating magnetic field, the material is magnetized repeatedly. At the same time, continuous friction between the magnetic domains inside it generates heat, which is called hysteresis loss heating. The higher the frequency of the magnetic flux change, the faster the temperature rise rate.

[0053] Magnetic flux: Refers to magnetic flux. In a uniform magnetic field with magnetic flux density B, there is a plane with an area S and perpendicular to the magnetic field direction. The product of the magnetic flux density B and the area S is the magnetic flux passing through this plane, abbreviated as magnetic flux, usually represented by the letter φ.

[0054] Magnetic flux density: The magnetic force lines perpendicular to the unit area are called magnetic flux density, abbreviated as magnetic flux density. It reflects the density of magnetic force lines quantitatively and is commonly represented by the symbol B.

[0055] Ferromagnetic materials: Include iron, nickel, cobalt, and their alloys.

[0056] Embodiment 1

[0057] An embodiment of the present invention discloses an air compressor system for self-heating ice melting, as Figure 1 shown, including an air compressor and a controller.

[0058] The air compressor further includes a housing and a permanent magnet synchronous motor, a compressor, and a turboexpander located inside the housing. The housing, the impeller of the compressor, the turbine of the turboexpander, and the volute are all made of ferromagnetic materials or prepared by covering a ferromagnetic material coating on the surface of non-ferromagnetic materials.

[0059] One end of the rotating shaft of the permanent magnet synchronous motor is installed with a compressor, and the other end is installed with a turboexpander. The output end of the compressor is connected to the air inlet of the fuel cell stack. The recovery gas inlet of the turboexpander is connected to the tail gas outlet of the fuel cell stack.

[0060] The controller is used to identify whether there is a low-temperature icing phenomenon inside the air compressor when the air compressor starts; and, if so, control the quadrature axis current I q = 0, and the direct axis current I d is an alternating current with a set frequency and a set amplitude, and the air compressor is heated by eddy current and hysteresis loss until it is identified that the low-temperature icing phenomenon has been eliminated, and then the air compressor is started normally.

[0061] It should be noted that the above compressor, permanent magnet synchronous motor, and turboexpander can all adopt the structures of existing equipment, but the housing, the impeller of the compressor, the turbine of the turboexpander, and the volute need to be made of ferromagnetic materials or prepared by covering a ferromagnetic material coating on the surface of non-ferromagnetic materials.

[0062] During implementation, when the excitation current output by the controller causes a change in the magnetic field of the permanent magnet synchronous motor, then in the conductors within this magnetic field, including the stator core, rotor, housing, turbine of the expander, volute of the volute, and other conductor components of the permanent magnet synchronous motor, induced electromotive force and induced current will be generated, and then the phenomenon of eddy current heating will occur.

[0063] Most of the magnetic flux generated by the stator current-carrying coil will pass through the stator core and rotor. This part is called the main magnetic flux. Therefore, the eddy current heating power of the stator core and rotor will be higher than that of other conductor components. The stator core and rotor will transfer heat to the expander of the air compressor through heat transfer to increase the temperature inside the volute of the expander and thus achieve ice melting.

[0064] In the space around the current-carrying coil and part of the iron core, there is still a small amount of scattered magnetic flux. This part of the magnetic flux is called leakage magnetic flux. The leakage magnetic flux will pass through conductor components such as the housing, turbine of the expander, and volute. Therefore, the housing, turbine of the expander, and volute will also have the phenomenon of eddy current heating, and the temperature inside the volute of the expander will also increase through heat conduction, thus achieving ice melting.

[0065] Currently, the permanent magnet synchronous motor adopts FOC vector control (normal start of the air compressor). The three-phase current output by the controller can be converted into direct-axis current (I d ) and quadrature-axis current (I q ) through Clarke transformation and Park transformation, as shown in Figure 2 . Because the direction of the direct-axis current is the same as the magnetic field direction of the permanent magnet rotor, the direct-axis current can only control the magnetization or demagnetization of the motor magnetic field. The quadrature axis is perpendicular to the magnetic field direction of the permanent magnet rotor, so the quadrature-axis current controls the motor to generate torque. Before the cold start of the air compressor, in order to avoid jamming, the air compressor does not rotate (I q = 0). First, the air compressor body is heated by the method of eddy current heating. After the temperature inside the expander cavity is higher than 0°C and remains for a period of time, it is then started. Therefore, during the cold start of the air compressor, the quadrature-axis current I q should be controlled to be 0, so that the torque current of the air compressor is 0, that is, the air compressor does not generate torque, and the state of the air compressor not rotating is achieved. The direct-axis current I d outputs an alternating current with a specific frequency and specific amplitude to achieve a change in the magnetic field inside the motor, and then causes the conductors in this magnetic field to generate the phenomenon of eddy current heating, achieving ice melting.

[0066] When components such as the housing, impeller, turbine, and volute of the air compressor are made of ferromagnetic materials or are coated with ferromagnetic materials on the surface of non-ferromagnetic materials, while the alternating magnetic field generated by the motor achieves eddy current heating, it will also cause the ferromagnetic materials to be repeatedly magnetized, and the magnetic domains will continuously rub against each other to generate heat, that is, the temperature of components such as the housing, impeller, turbine, and volute of the air compressor will increase, thus achieving the ice melting function.

[0067] Compared with the prior art, the system provided in this embodiment solves the icing problem at the expansion end of the air compressor during low-temperature cold start by using the methods of eddy current heating and hysteresis loss heating. Specifically, when the housing, impeller, turbine, and volute of the air compressor are made of ferromagnetic materials or a ferromagnetic material coating is covered on the surface of non-ferromagnetic materials, the alternating magnetic field generated by the permanent magnet synchronous motor will cause the ferromagnetic materials to be repeatedly magnetized while realizing eddy current heating, and the magnetic domains will continuously rub against each other to generate heat, that is, the temperatures of components such as the housing, impeller, turbine, and volute of the air compressor are increased, thereby realizing the ice melting function.

[0068] Embodiment 2

[0069] Based on the improvement of Embodiment 1, the controller further includes a data acquisition unit and a data processing and control unit that are connected in sequence.

[0070] The data acquisition unit is used to acquire the ambient temperature of the air compressor system in real time and send it to the data processing and control unit.

[0071] The data processing and control unit is used to judge whether there is a low-temperature icing phenomenon inside the air compressor according to the received ambient temperature when the air compressor starts; if so, control the quadrature axis current I q = 0, and at the same time, the direct axis current I d is an alternating current with a set frequency and set amplitude, and performs eddy current heating and hysteresis loss heating on the air compressor. During the heating process, it identifies whether the low-temperature icing phenomenon inside the air compressor is eliminated. After elimination, the air compressor is started normally, and its control principle is as Figure 3 shown. The method of controlling the quadrature axis current I q and the direct axis current I d is the prior art. Exemplarily, reference can be made to Patent CN201611129148.0.

[0072] It should be noted that if it is identified that there is no low-temperature icing phenomenon inside the air compressor when the air compressor starts, the air compressor is started normally.

[0073] Preferably, the data acquisition unit further includes an ambient temperature sensor and an infrared temperature sensor.

[0074] The ambient temperature sensor is arranged in the external environment of the air compressor and is used to acquire the ambient temperature at the installation position as the ambient temperature of the air compressor system.

[0075] The infrared temperature sensor is arranged on the inner wall of the intake pipeline of the turbine expander and is used to acquire the ambient temperature at the installation position as the internal temperature of the turbine expander.

[0076] Preferably, the data processing and control unit executes the following program:

[0077] S1. Identify whether an air compressor start signal sent by the fuel cell system controller is received; if yes, proceed to the next step;

[0078] S2. Obtain the ambient temperature of the air compressor at the current moment, and determine whether there is a low-temperature icing phenomenon inside the air compressor; if yes, proceed to the next step, otherwise, start the air compressor normally; Exemplarily, if the ambient temperature is lower than 0°C, it is determined that there is a low-temperature icing phenomenon, otherwise there is no low-temperature icing phenomenon;

[0079] S3. Control the quadrature-axis current I q of the permanent magnet synchronous motor to be 0, and at the same time, control the direct-axis current I d to be an alternating current with a set frequency and set amplitude to perform eddy current heating and hysteresis loss heating on the air compressor;

[0080] S4. Obtain the heating time t based on the ambient temperature of the air compressor system and the internal temperature of the turboexpander at the current moment, and until the low-temperature icing phenomenon inside the air compressor is determined to have been eliminated after reaching the heating time t, adjust the direct-axis current I d of the permanent magnet synchronous motor to be 0, and then start the air compressor normally.

[0081] Preferably, the heating time t is determined by the following formula:

[0082] t = a(T2 - T1) 3 + b(T2 - T1) 2 + c(T2 - T1)+ dT2 + e

[0083] In the formula, T2 is the ambient temperature of the air compressor system, T1 is the internal temperature of the turboexpander, and a, b, c, d, e are coefficients calibrated according to the heating time for eliminating low-temperature icing phenomena in the laboratory.

[0084] Preferably, the air compressor system further includes a flow control valve. The output port of the compressor is connected to the air inlet of the fuel cell stack through the flow control valve.

[0085] Preferably, an air filter is provided at the intake end of the compressor. Filtering impurities in the intake air can effectively improve the overall service life of the air compressor and the fuel cell.

[0086] Preferably, the turbine of the turboexpander and the impeller of the compressor are respectively installed at both ends of the rotating shaft of the permanent magnet synchronous motor, which is convenient for realizing synchronous control and improving control efficiency. It reduces the power consumption of the motor, can also maintain the rotation speed of the rotating shaft, thereby saving electric energy and improving the working efficiency of the fuel cell.

[0087] Preferably, the data acquisition unit further comprises an impeller speed and torque monitoring subunit (optional camera). The impeller speed and torque monitoring subunit is used to monitor the speed and torque of the impeller in the compressor and send them to the data processing and control unit.

[0088] Preferably, the data processing and control unit may also execute the following procedure to predict whether low-temperature icing still exists before executing step S2:

[0089] S201. Start the air compressor and obtain the speed and torque of the impeller in the compressor;

[0090] S202. Identify whether the speed of the impeller in the compressor is continuously zero within a preset time and the torque of the compressor is higher than the set torque. If so, determine that low-temperature icing exists inside the air compressor; otherwise, determine that low-temperature icing does not exist inside the air compressor.

[0091] By using a variety of identification methods to eliminate under-judgment or misjudgment of low-temperature icing phenomena, the user experience can be effectively improved.

[0092] Preferably, the data acquisition unit further comprises a gas temperature-flow integrated sensor. The gas temperature-flow integrated sensor is arranged at the air inlet of the turbo expander and is used to acquire the gas temperature and flow at the arranged position.

[0093] Preferably, the data processing and control unit also executes the following program:

[0094] S5. After the air compressor is started, the direct-axis current I of the permanent magnet synchronous motor is measured based on the gas temperature and flow rate collected by the gas temperature-flow integrated sensor. d The amplitude and frequency of the sensor are adjusted synchronously. The specific value can be obtained based on the laboratory calibration data.

[0095] Preferably, the rotating shaft of the permanent magnet synchronous motor is supported at both ends of the permanent magnet synchronous motor by high-speed rolling bearings or high-speed sliding bearings. In addition, a flow distribution valve is provided between the recovered gas inlet of the turbo expander and the exhaust port of the fuel cell.

[0096] Preferably, the heating time t is the shortest heating time required for heating the volute to achieve the deicing effect at the ambient temperature, and the time can be obtained through laboratory calibration.

[0097] Preferably, the controller has a display module, the display screen of the display module displays the current ambient temperature, the result of identifying the presence of low-temperature icing inside the air compressor based on the ambient temperature, the startup status of the air compressor, and the temperature and flow rate of the gas at the air inlet of the turbo expander containing air exhaust energy information (to facilitate developers to improve the design of control parameters).

[0098] Compared with Embodiment 1, the air intake device provided in this embodiment has the following

[0099] Advantageous effects:

[0100] 1. When the air compressor is cold-started, it does not rotate first. Control the quadrature-axis current I q = 0, and the direct-axis current I d is an alternating current with a set frequency and set amplitude to perform eddy current heating on the air compressor for a set heating time. After the ice melting is completed, the air compressor is then started normally.

[0101] 2. The ice on the internal gas pipeline of the air compressor is melted by heating methods based on two principles: eddy current heating and hysteresis loss heating. The heating effect is good and the ice melting speed is fast.

[0102] 3. It avoids the problems of complex structure, increased cost, and cumbersome control of the air compressor caused by using a heating water jacket and a PTC heating tape.

[0103] 4. Adding an air filter can improve the service life of the air compressor. A flow distribution valve is added, which can adjust the flow rate of the exhaust gas entering the turboexpander according to requirements.

[0104] The embodiments of the present disclosure have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the prior art, or to enable other ordinary skill in the art in the technical field to understand the disclosed embodiments.

Claims

1. An air compressor system with self-heating and ice melting, characterized in that It includes an air compressor and a controller; among them, the air compressor further includes a housing and a permanent magnet synchronous motor, a compressor, and a turboexpander located inside the housing; the housing, the impeller of the compressor, the turbine and the volute of the turboexpander are all made of ferromagnetic materials or prepared by covering a ferromagnetic material coating on the surface of non-ferromagnetic materials; One end of the rotating shaft of the permanent magnet synchronous motor is equipped with a compressor, and the other end is equipped with a turboexpander; the recovery gas inlet of the turboexpander is connected to the exhaust gas outlet of the fuel cell stack; A controller, configured to identify whether there is a low-temperature icing phenomenon inside the air compressor when the air compressor starts; and, if so, control the quadrature-axis current I q = 0, and the direct-axis current I d is an alternating current with a set frequency and a set amplitude, to perform eddy current heating and hysteresis loss heating on the air compressor until it is identified that the low-temperature icing phenomenon has been eliminated, and then start the air compressor normally; The controller further includes: A data acquisition unit, which is used to obtain the ambient temperature of the air compressor system in real time and send it to the data processing and control unit; A data processing and control unit is used to determine whether there is a low-temperature icing phenomenon inside the air compressor according to the received ambient temperature when the air compressor starts; if so, control the quadrature-axis current I of the permanent magnet synchronous motor q = 0. At the same time, the direct-axis current I d is an alternating current with a set frequency and a set amplitude, and is used to perform eddy current heating and hysteresis loss heating on the air compressor. During the heating process, it is identified whether the low-temperature icing phenomenon inside the air compressor is eliminated. After elimination, the air compressor is started normally; The data acquisition unit further includes: An ambient temperature sensor, which is arranged in the external environment of the air compressor and is used to obtain the ambient temperature at the installation position as the ambient temperature of the air compressor system; An infrared temperature sensor, which is arranged on the inner wall of the intake pipeline of the turboexpander and is used to obtain the ambient temperature at the installation position as the internal temperature of the turboexpander; The data processing and control unit executes the following program: Identify whether it has received the air compressor start signal sent by the fuel cell system controller; if so, execute the next step; Obtain the ambient temperature of the air compressor at the current moment and judge whether there is a low-temperature icing phenomenon inside the air compressor; if so, execute the next step, otherwise, start the air compressor normally; Control the quadrature-axis current I of the permanent magnet synchronous motor q = 0. At the same time, control the direct-axis current I d to be an alternating current with a set frequency and set amplitude, and perform eddy current heating and hysteresis loss heating on the air compressor; Obtain the heating time t based on the ambient temperature of the air compressor system at the current moment and the internal temperature of the turboexpander. It is determined that the low-temperature icing phenomenon inside the air compressor has been eliminated until the heating time t is reached, and then adjust the direct-axis current I of the permanent magnet synchronous motor d = 0, and then start the air compressor normally; The heating time t is determined by the following formula: t = a(T2 - T1) 3 + b(T2 - T1) 2 + c(T2 - T1)+ dT2 + e In the formula, T2 is the ambient temperature of the air compressor system, T1 is the internal temperature of the turboexpander, and a, b, c, d, e are coefficients calibrated according to the heating time for eliminating low-temperature icing phenomena in the laboratory; It also includes a flow control valve; the output port of the compressor is connected to the air inlet of the fuel cell stack through this flow control valve; and, The turbine of the turboexpander and the impeller of the compressor are respectively installed at both ends of the rotating shaft of the permanent magnet synchronous motor; The data acquisition unit also includes: An impeller speed and torque monitoring sub-unit, which is used to monitor the speed and torque of the impeller in the compressor and send them to the data processing and control unit; and, The data processing and control unit also executes the following program: Start the air compressor and obtain the speed and torque of the impeller in the compressor; Identify whether it meets the condition that the speed of the impeller in the compressor remains zero for a preset duration and the torque of the compressor is higher than the set torque; if so, determine that there is a low-temperature icing phenomenon inside the air compressor, otherwise, determine that there is no low-temperature icing phenomenon inside the air compressor.

2. The self-heating ice-melting air compressor system according to claim 1, wherein The data acquisition unit also includes: A gas temperature-flow integrated sensor, which is arranged at the air inlet of the turboexpander and is used to obtain the gas temperature and flow at the installation position; and, The data processing and control unit also executes the following program: After the air compressor starts, according to the gas temperature and flow rate collected by the gas temperature-flow integrated sensor, the amplitude and frequency of the direct-axis current I d of the permanent magnet synchronous motor are synchronously adjusted.

3. The air compressor system for self-heating ice melting according to claim 2, characterized in that, The rotating shaft is supported at both ends of the permanent magnet synchronous motor by high-speed rolling bearings or high-speed sliding bearings; and, A flow distribution valve is arranged between the recovery gas inlet of the turboexpander and the exhaust port of the fuel cell.

4. The self-heating ice-melting air compressor system according to claim 1, wherein The heating time t is the shortest heating time required to heat the volute to achieve the ice melting effect at this ambient temperature.

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