Magnetic suspension motor, cooling method and device thereof, storage medium and program product

Abstract

The invention discloses a cooling method and device of a magnetic suspension motor, the magnetic suspension motor, a storage medium and a computer program product, a coolant pipeline is arranged at a motor winding of the magnetic suspension motor, and an electronic expansion valve is arranged on the coolant pipeline; the method comprises the steps that after a magnetic suspension motor starts to work, the target opening degree of the electronic expansion valve is determined according to the temperature of a motor winding; the electronic expansion valve is powered on in a pulse mode, and the power-on time of the electronic expansion valve is controlled according to the action frequency of the electronic expansion valve, so that the power-on time of the electronic expansion valve is shortened while the opening degree of the electronic expansion valve reaches the target opening degree, and heat at the position of the electronic expansion valve is reduced. According to the scheme, the electronic expansion valve is powered on in a pulse mode, and the power-on time is controlled according to the action frequency of the electronic expansion valve, so that the power-on time of the electronic expansion valve is shortened, heat at the electronic expansion valve is reduced, high-temperature failure of the electronic expansion valve is avoided, and stable operation of the magnetic suspension motor is ensured.

Description

Technical Field

[0001] The present invention belongs to the field of magnetic levitation motors, and in particular relates to a cooling method and device for a magnetic levitation motor, a magnetic levitation motor, a storage medium and a computer program product. Background Art

[0002] During the operation of the magnetic levitation motor, the motor winding will generate a lot of heat due to the movement of the rotor cutting the magnetic flux lines, and coolant is needed to cool the motor winding.

[0003] When cooling the motor windings, by installing an electronic expansion valve at the front end of the motor winding cooling channel, the flow of the coolant can be accurately controlled, so that the motor winding temperature is maintained within a stable range. However, since the motor power changes dynamically, the motor winding temperature will also fluctuate accordingly. In order to stabilize the temperature of the motor winding, the electronic expansion valve will be continuously powered on and frequently operated, thereby accumulating heat at the electronic expansion valve. Excessive heat can easily cause the electronic expansion valve to fail, which in turn makes it impossible to effectively control the temperature of the motor winding.

[0004] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0005] The purpose of the present invention is to provide a cooling method and device for a magnetic levitation motor, a magnetic levitation motor, a storage medium and a computer program product, so as to solve the problem in related schemes that excessive heat accumulation at the electronic expansion valve causes failure of the electronic expansion valve, thereby failing to effectively control the temperature of the motor winding, so as to achieve the effect of reducing the power-on time of the electronic expansion valve and reducing the heat at the electronic expansion valve, thereby avoiding high-temperature failure of the electronic expansion valve, effectively controlling the temperature of the motor winding and ensuring the stable operation of the magnetic levitation motor.

[0006] The present invention provides a cooling method for a magnetic levitation motor, wherein a coolant pipeline is provided at a motor winding of the magnetic levitation motor; an electronic expansion valve is provided on the coolant pipeline; the method comprises: after the magnetic levitation motor starts to work, obtaining the temperature of the motor winding and the operating frequency of the electronic expansion valve; determining the target opening of the electronic expansion valve according to the temperature of the motor winding; energizing the electronic expansion valve in a pulse manner, and controlling the power-on time of the electronic expansion valve according to the operating frequency of the electronic expansion valve, so as to reduce the power-on time of the electronic expansion valve and reduce the heat at the electronic expansion valve while making the opening of the electronic expansion valve reach the target opening.

[0007] In some embodiments, the electronic expansion valve has a four-phase coil and a valve body; by controlling the power supply of each phase coil of the four-phase coil in sequence according to a set power-on sequence, the valve body is activated to change the opening of the electronic expansion valve so that the electronic expansion valve reaches the target opening.

[0008] In some embodiments, determining the target opening of the electronic expansion valve according to the temperature of the motor winding includes: bringing the temperature of the motor winding into a preset calculation formula to calculate the target opening of the electronic expansion valve; the preset calculation formula is:

[0009] U pre-sat =U p (k)+U i (k);

[0010] Among them, U pre-sat is the target opening of the electronic expansion valve; U p (k) is the proportional output, U p (k) = K p err(k), err(k) = -(Ref - Fdb), Fdb is the temperature of the motor winding, Ref is the reference temperature of the motor winding, K p is the proportional gain coefficient; U i (k) is the integral output.

[0011] In some embodiments, the power-on time of the electronic expansion valve is controlled according to the operating frequency of the electronic expansion valve, including: determining the inverse of the operating frequency of the electronic expansion valve as the pulse period; and taking the result of multiplying the pulse period by a set duty cycle as the power-on time of the electronic expansion valve.

[0012] Matching the above method, the present invention provides a cooling device for a magnetic levitation motor on the other hand, wherein a coolant pipe is provided at the motor winding of the magnetic levitation motor; an electronic expansion valve is provided on the coolant pipe; the cooling device comprises: an acquisition unit, configured to acquire the temperature of the motor winding and the operating frequency of the electronic expansion valve after the magnetic levitation motor starts working; a control unit, configured to determine the target opening of the electronic expansion valve according to the temperature of the motor winding; the control unit is further configured to energize the electronic expansion valve in a pulse manner, and control the power-on time of the electronic expansion valve according to the operating frequency of the electronic expansion valve, so as to reduce the power-on time of the electronic expansion valve and reduce the heat at the electronic expansion valve while making the opening of the electronic expansion valve reach the target opening.

[0013] In some embodiments, the electronic expansion valve has a four-phase coil and a valve body; by controlling the power supply of each phase coil of the four-phase coil in sequence according to a set power-on sequence, the valve body is activated to change the opening of the electronic expansion valve so that the electronic expansion valve reaches the target opening.

[0014] In some embodiments, the control unit determines the target opening of the electronic expansion valve according to the temperature of the motor winding, including: bringing the temperature of the motor winding into a preset calculation formula to calculate the target opening of the electronic expansion valve; the preset calculation formula is:

[0015] U pre-sat =U p (k)+U i (k);

[0016] Among them, U pre-sat is the target opening of the electronic expansion valve; U p (k) is the proportional output, U p (k) = K p err(k), err(k) = -(Ref - Fdb), Fdb is the temperature of the motor winding, Ref is the reference temperature of the motor winding, K p is the proportional gain coefficient; U i (k) is the integral output.

[0017] In some embodiments, the control unit controls the power-on time of the electronic expansion valve according to the operating frequency of the electronic expansion valve, including: determining the inverse of the operating frequency of the electronic expansion valve as the pulse period; and taking the result of multiplying the pulse period by a set duty cycle as the power-on time of the electronic expansion valve.

[0018] Matching the above device, the present invention provides a magnetic levitation motor on another aspect, including: the cooling device of the magnetic levitation motor described above.

[0019] Matching the above method, the present invention provides a storage medium on another aspect, wherein the storage medium includes a stored program, wherein when the program is running, the device where the storage medium is located is controlled to execute the above-mentioned cooling method for the magnetic levitation motor.

[0020] Matching the above method, the present invention provides a computer program product on another aspect, wherein the computer program product includes a computer program, and when the computer program product is processed and executed, the steps of the above magnetic levitation motor cooling method are implemented.

[0021] The scheme of the present invention is to set an electronic expansion valve on the coolant pipeline of the motor winding to control the flow of the coolant; after the magnetic levitation motor starts working, the target opening of the electronic expansion valve is determined according to the temperature of the motor winding; the electronic expansion valve is energized in a pulse manner, and the power-on time is controlled according to the operating frequency of the electronic expansion valve, so as to reduce the power-on time of the electronic expansion valve and reduce the heat at the electronic expansion valve while making the electronic expansion valve reach the target opening. By energizing the electronic expansion valve in a pulse manner and controlling the power-on time according to the operating frequency of the electronic expansion valve, the power-on time of the electronic expansion valve is reduced, the heat at the electronic expansion valve is reduced, and the failure of the electronic expansion valve due to high temperature is avoided, so that the temperature of the motor winding is effectively controlled, and the stable operation of the magnetic levitation motor is ensured.

[0022] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention.

[0023] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of a flow chart of an embodiment of a cooling method for a magnetic levitation motor of the present invention;

[0025] Figure 2 It is a structural schematic diagram of an embodiment of a cooling device for a magnetic levitation motor of the present invention;

[0026] Figure 3 It is a structural schematic diagram of the motor winding cooling pipeline;

[0027] Figure 4 This is a schematic diagram of the wiring method and the opening and closing method of the electronic expansion valve;

[0028] Figure 5 This is the pulse control current diagram of the electronic expansion valve;

[0029] Figure 6 A schematic diagram of a flow chart for controlling the opening of an electronic expansion valve;

[0030] Figure 7 This is a flow chart of controlling the power supply of an electronic expansion valve by pulse mode.

[0031] In conjunction with the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:

[0032] 102 - acquisition unit; 104 - control unit. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] According to an embodiment of the present invention, a cooling method for a magnetic levitation motor is provided, wherein a coolant pipeline is provided at the motor winding of the magnetic levitation motor; a coolant flows in the coolant pipeline, and the coolant can cool the motor winding; an electronic expansion valve is provided on the coolant pipeline; the electronic expansion valve is used to control the flow rate of the coolant. Figure 3 As shown, the coolant pipeline is wound around the motor winding, and the coolant enters the pipeline through the cooling inlet and cools the motor winding. After that, the coolant flows out from the return air pipeline and enters the intake air pipeline, completing a cycle. An electronic expansion valve is provided at the cooling inlet. By controlling the opening size of the electronic expansion valve, the coolant flow rate flowing into the coolant pipeline is controlled. When the coolant flow rate is large, the temperature of the motor winding is reduced, and when the coolant flow rate is small, the temperature of the motor winding is increased, thereby keeping the temperature of the motor winding within a certain range.

[0035] In some embodiments, the electronic expansion valve has a four-phase coil and a valve body; by controlling the power supply of each phase coil of the four-phase coil in sequence according to a set power-on sequence, the valve body is activated to change the opening of the electronic expansion valve so that the electronic expansion valve reaches the target opening.

[0036] The electronic expansion valve is essentially a stepper motor. The electronic expansion valve in this scheme belongs to a five-wire four-phase unipolar stepper motor according to the winding method of the coil. Figure 4 As shown in (a) and (b), the electronic expansion valve adopts the common anode wiring method. The out1 of the drive signal is connected to the A terminal of the electronic expansion valve, and the out2 of the drive signal is connected to the The out3 of the drive signal is connected to the B end of the electronic expansion valve, and the out4 of the drive signal is connected to the terminals, where the COM terminal is connected to the +24V power supply.

[0037] The control mode of the electronic expansion valve is four-phase eight-beat control mode, such as Figure 4As shown in (c), during the control process, one or two phases are always energized. The shaded part in the figure indicates that the phase is in the energized state, that is, each stepping action consists of energizing and de-energizing two or one phase out of the four phases. In the first beat, phase A is energized, so that the rotor of the motor is attracted by the magnetic force generated by the coil, and the rotor turns to a position aligned with the coil of phase A; in the second beat, phases A and B are energized, and the rotor is attracted by the magnetic force of the two coils and moves to a position between the two coils; in the third beat, only phase B is energized, and the rotor turns to a position aligned with the collar of phase B. The fourth to eighth beats are analogous, that is, single-phase energization and two-phase energization are alternated to rotate the rotor, thereby accurately controlling the operating frequency and opening of the electronic expansion valve.

[0038] For Figure 4 The wiring method of the electronic expansion valve shown in (a) and (b) is generally powered by square wave control, such as Figure 5 The waveform shown in (a) indicates that during the control process of the electronic expansion valve, one or two phases are always energized. However, since the electronic expansion valve is always energized, the heat at the electronic expansion valve will continue to accumulate. If this heat cannot be dissipated in time, the control of the electronic expansion valve may fail, and the temperature of the motor winding cannot be controlled.

[0039] This solution controls the electronic expansion valve by adopting a pulse control method, and controls the power-on time of each phase during each beat, thereby reducing the power-on time of each phase, reducing the heat generated by the coil, and allowing the heat at the electronic expansion valve to be dissipated in time, achieving a cooling effect.

[0040] like Figure 1 The flowchart of an embodiment of the method of the present invention is shown in FIG. The cooling method of the magnetic levitation motor may include: steps S110 to S130.

[0041] In step S110, after the magnetic levitation motor starts to work, the temperature of the motor winding and the operating frequency of the electronic expansion valve are obtained.

[0042] The action frequency of the electronic expansion valve is set by the system, which can be the frequency of the electronic expansion valve regulating the coolant flow, that is, the number of times the electronic expansion valve regulates the coolant flow per unit time. Since the temperature sampling point of the motor winding is no longer in the same position as the electronic expansion valve, it is usually set at the outlet of the return air pipeline. Therefore, when the opening of the electronic expansion valve increases, the temperature at the inlet of the coolant pipeline where the electronic expansion valve is located will decrease, while the temperature of the sampling point will not change immediately; when the opening of the electronic expansion valve decreases, the temperature at the inlet of the coolant pipeline where the electronic expansion valve is located will rise, while the temperature of the sampling point will not change immediately, so there is a lag in the temperature change detection of the motor winding. Therefore, when the temperature sampling point of the motor winding changes in temperature, it means that the temperature of the entire motor winding is basically the same. According to the characteristic that the temperature sampling point will change in temperature only after a certain period of time after the opening of the electronic expansion valve changes, the service life of the electronic expansion valve can be extended by extending the control cycle of the electronic expansion valve.

[0043] In step S120 , the target opening degree of the electronic expansion valve is determined according to the temperature of the motor winding.

[0044] In some embodiments, in step S120, the specific process of determining the target opening of the electronic expansion valve according to the temperature of the motor winding includes: substituting the temperature of the motor winding into a preset calculation formula to calculate the target opening of the electronic expansion valve.

[0045] The calculation formula for calculating the target opening of the electronic expansion valve according to the motor winding temperature can be a PI calculation formula, specifically:

[0046] U pre-sat =U p (k)+U i (k);

[0047] In the formula, U pre-sat is the target opening of the electronic expansion valve, U p (k) is the proportional output, U p (k) = K p err(k), err(k) = -(Ref-Fdb), the negative value is because when the temperature of the motor winding is lower than the reference temperature, the opening of the electronic expansion valve needs to be adjusted, and the relationship with Ref-Fdb is negatively correlated; K p is the proportional gain coefficient; Ref is the reference temperature of the motor winding, Fdb is the temperature of the motor winding; Ui(k) is the integral output, Ui(k)=U i (k-1)+KiU p (k), default

[0048] Optionally, after obtaining the target opening of the electronic expansion valve according to the PI calculation formula, the target opening can also be limited to prevent the electronic expansion valve from being oversaturated. The formula for limiting is:

[0049]

[0050] U(k) is the target opening of the electronic expansion valve after limiting. max is the maximum opening of the electronic expansion valve, U min is the minimum opening of the electronic expansion valve. By calculating the opening of the electronic expansion valve according to the PI calculation formula, when the motor winding temperature is greater than the reference temperature, the opening of the electronic expansion valve will increase, and when the motor winding temperature is less than the reference temperature, the opening of the electronic expansion valve will decrease, and the greater the temperature difference, the greater the opening adjustment amount. By limiting the pre-output opening of the electronic expansion valve, it is possible to prevent the electronic expansion valve from entering a saturated state during the adjustment process, making the opening adjustment more sensitive and the motor winding temperature control more precise.

[0051] In step S130, the electronic expansion valve is energized in a pulse manner, and the power-on time of the electronic expansion valve is controlled according to the operating frequency of the electronic expansion valve, so as to reduce the power-on time of the electronic expansion valve and reduce the heat at the electronic expansion valve while making the opening of the electronic expansion valve reach the target opening.

[0052] The pulse mode is a power supply mode that provides electrical energy through a periodic pulse signal, and the pulse signal is provided by a pulse generator.

[0053] Figure 6 The flow chart of controlling the opening of the electronic expansion valve is as follows: Figure 6 As shown, the method includes:

[0054] Step 1: upload the temperature of the motor winding to the host computer, and the host computer calculates the preset opening required by the electronic expansion valve according to the temperature of the motor winding.

[0055] Step 2: The host computer controls the electronic expansion valve according to the set action frequency, and performs pulse control according to the set duty cycle, so that the electronic expansion valve reaches a preset opening.

[0056] By controlling the power-on operation of the electronic expansion valve in a pulse manner, the power-on time of each phase coil in the electronic expansion valve is reduced without affecting the operating frequency of the electronic expansion valve, thereby reducing the heat generated by the coil and effectively dissipating the heat at the electronic expansion valve, thereby ensuring the stable operation of the electronic expansion valve and increasing the service life of the electronic expansion valve, avoiding the inability to effectively control the temperature of the motor winding due to failure of the electronic expansion valve, and ensuring the stable operation of the magnetic levitation motor.

[0057] In some embodiments, in step S130, the specific process of controlling the power-on time of the electronic expansion valve according to the operating frequency of the electronic expansion valve includes: determining the inverse of the operating frequency of the electronic expansion valve as the pulse period; and taking the result of multiplying the pulse period by a set duty cycle as the power-on time of the electronic expansion valve.

[0058] When controlling the power-on time of the electronic expansion valve, the host computer will first set the operating frequency f of the electronic expansion valve, and calculate the conduction time based on the operating frequency f. The conduction time T = (1 / f) * duty cycle, and the duty cycle is set according to the actual situation. Then, according to the conduction time T, the pulse control method is used to control the conduction time of each phase coil in the electronic expansion valve. Figure 5 As shown in (b), taking the first beat as an example, phase A is energized only part of the time, with a high level when energized and a low level when not energized. The electronic expansion valve works normally when energized, and does not work when not energized. At this time, the coil does not generate heat and will dissipate the accumulated heat. Among them,

[0059] ˉˉ

[0060] As long as the voltages between terminals A, A, B, and B are the same as the voltage between terminals COM, the coil is in a power-off state. For example, if the out1 to out4 terminals of the upper computer control driver chip are all at a high level, the coil can be powered off.

[0061] The pulse control method not only reduces the temperature at the electronic expansion valve, but also does not change the operating frequency of the electronic expansion valve.

[0062] Figure 7 The schematic diagram of the process of controlling the power supply of the electronic expansion valve by pulse mode is as follows:

[0063] Step 11, the host computer sets the operating frequency f of the electronic expansion valve, and calculates the duty cycle time T = (1 / f) * duty cycle, where the duty cycle is the set value.

[0064] Step 12, the host computer controls the driver chip pins in sequence to control the power-on of each phase of the electronic expansion valve. After the power-on time reaches the duty cycle time, the driver chip output is controlled to be high level, so that the electronic expansion valve is powered off.

[0065] By adopting the technical solution of this embodiment, an electronic expansion valve is provided on the coolant pipeline of the motor winding to control the flow of the coolant; after the magnetic levitation motor starts working, the target opening of the electronic expansion valve is determined according to the temperature of the motor winding; the electronic expansion valve is energized in a pulse manner, and the power-on time is controlled according to the operating frequency of the electronic expansion valve, so as to reduce the power-on time of the electronic expansion valve and reduce the heat at the electronic expansion valve while making the electronic expansion valve reach the target opening. By energizing the electronic expansion valve in a pulse manner and controlling the power-on time according to the operating frequency of the electronic expansion valve, the power-on time of the electronic expansion valve is reduced, the heat at the electronic expansion valve is reduced, and the failure of the electronic expansion valve due to high temperature is avoided, so that the temperature of the motor winding is effectively controlled, and the stable operation of the magnetic levitation motor is ensured.

[0066] According to an embodiment of the present invention, a cooling device for a magnetic levitation motor corresponding to the cooling method for a magnetic levitation motor is also provided. A coolant pipeline is provided at the motor winding of the magnetic levitation motor; a coolant flows in the coolant pipeline, and the coolant can cool the motor winding; an electronic expansion valve is provided on the coolant pipeline; the electronic expansion valve is used to control the flow rate of the coolant. Figure 3 As shown, the coolant pipeline is wound around the motor winding, and the coolant enters the pipeline through the cooling inlet and cools the motor winding. After that, the coolant flows out from the return air pipeline and enters the intake air pipeline, completing a cycle. An electronic expansion valve is provided at the cooling inlet. By controlling the opening size of the electronic expansion valve, the coolant flow rate flowing into the coolant pipeline is controlled. When the coolant flow rate is large, the temperature of the motor winding is reduced, and when the coolant flow rate is small, the temperature of the motor winding is increased, thereby keeping the temperature of the motor winding within a certain range.

[0067] In some embodiments, the electronic expansion valve has a four-phase coil and a valve body; by controlling the power supply of each phase coil of the four-phase coil in sequence according to a set power-on sequence, the valve body is activated to change the opening of the electronic expansion valve so that the electronic expansion valve reaches the target opening.

[0068] The electronic expansion valve is essentially a stepper motor. The electronic expansion valve in this scheme belongs to a five-wire four-phase unipolar stepper motor according to the winding method of the coil. Figure 4 As shown in (a) and (b), the electronic expansion valve adopts the common anode wiring method. The out1 of the drive signal is connected to the A terminal of the electronic expansion valve, and the out2 of the drive signal is connected to the The out3 of the drive signal is connected to the B end of the electronic expansion valve, and the out4 of the drive signal is connected to the terminals, where the COM terminal is connected to the +24V power supply.

[0069] The control mode of the electronic expansion valve is four-phase eight-beat control mode, such as Figure 4 As shown in (c), during the control process, one or two phases are always energized. The shaded part in the figure indicates that the phase is in the energized state, that is, each stepping action consists of energizing and de-energizing two or one phase out of the four phases. In the first beat, phase A is energized, so that the rotor of the motor is attracted by the magnetic force generated by the coil, and the rotor turns to a position aligned with the coil of phase A; in the second beat, phases A and B are energized, and the rotor is attracted by the magnetic force of the two coils and moves to a position between the two coils; in the third beat, only phase B is energized, and the rotor turns to a position aligned with the collar of phase B. The fourth to eighth beats are analogous, that is, single-phase energization and two-phase energization are alternated to rotate the rotor, thereby accurately controlling the operating frequency and opening of the electronic expansion valve.

[0070] For Figure 4 The wiring method of the electronic expansion valve shown in (a) and (b) is generally powered by square wave control, such as Figure 5 The waveform shown in (a) indicates that during the control process of the electronic expansion valve, one or two phases are always energized. However, since the electronic expansion valve is always energized, the heat at the electronic expansion valve will continue to accumulate. If this heat cannot be dissipated in time, the control of the electronic expansion valve may fail, and the temperature of the motor winding cannot be controlled.

[0071] This solution controls the electronic expansion valve by adopting a pulse control method, and controls the power-on time of each phase during each beat, thereby reducing the power-on time of each phase, reducing the heat generated by the coil, and allowing the heat at the electronic expansion valve to be dissipated in time, achieving a cooling effect.

[0072] See also Figure 2 The schematic diagram of the structure of an embodiment of the device of the present invention is shown. The cooling device of the magnetic levitation motor may include: an acquisition unit 102 and a control unit 104.

[0073] The acquisition unit 102 is configured to acquire the temperature of the motor winding and the operating frequency of the electronic expansion valve after the magnetic levitation motor starts to work. The specific functions and processing of the acquisition unit 102 refer to step S110.

[0074] The action frequency of the electronic expansion valve is set by the system, which can be the frequency of the electronic expansion valve regulating the coolant flow, that is, the number of times the electronic expansion valve regulates the coolant flow per unit time. Since the temperature sampling point of the motor winding is no longer in the same position as the electronic expansion valve, it is usually set at the outlet of the return air pipeline. Therefore, when the opening of the electronic expansion valve increases, the temperature at the inlet of the coolant pipeline where the electronic expansion valve is located will decrease, while the temperature of the sampling point will not change immediately; when the opening of the electronic expansion valve decreases, the temperature at the inlet of the coolant pipeline where the electronic expansion valve is located will rise, while the temperature of the sampling point will not change immediately, so there is a lag in the temperature change detection of the motor winding. Therefore, when the temperature sampling point of the motor winding changes in temperature, it means that the temperature of the entire motor winding is basically the same. According to the characteristic that the temperature sampling point will change in temperature only after a certain period of time after the opening of the electronic expansion valve changes, the service life of the electronic expansion valve can be extended by extending the control cycle of the electronic expansion valve.

[0075] The control unit 104 is configured to determine the target opening of the electronic expansion valve according to the temperature of the motor winding. The specific functions and processing of the control unit 104 refer to step S120.

[0076] In some embodiments, the control unit 104 determines the specific process of the target opening of the electronic expansion valve according to the temperature of the motor winding, including: substituting the temperature of the motor winding into a preset calculation formula to calculate the target opening of the electronic expansion valve.

[0077] The calculation formula for calculating the target opening of the electronic expansion valve according to the motor winding temperature can be a PI calculation formula, specifically:

[0078] U pre-sat =U p (k)+U i (k);

[0079] In the formula, U pre-sat is the target opening of the electronic expansion valve, U p (k) is the proportional output, U p (k) = K p err(k), err(k) = -(Ref-Fdb), the negative value is because when the temperature of the motor winding is lower than the reference temperature, the opening of the electronic expansion valve needs to be adjusted, and the relationship with Ref-Fdb is negatively correlated; K p is the proportional gain coefficient; Ref is the reference temperature of the motor winding, Fdb is the temperature of the motor winding; Ui(k) is the integral output, Ui(k)=U i (k-1)+KiU p (k), default

[0080] Optionally, after obtaining the target opening of the electronic expansion valve according to the PI calculation formula, the target opening can also be limited to prevent the electronic expansion valve from being oversaturated. The formula for limiting is:

[0081]

[0082] U(k) is the target opening of the electronic expansion valve after limiting. max is the maximum opening of the electronic expansion valve, U min is the minimum opening of the electronic expansion valve. By calculating the opening of the electronic expansion valve according to the PI calculation formula, when the motor winding temperature is greater than the reference temperature, the opening of the electronic expansion valve will increase, and when the motor winding temperature is less than the reference temperature, the opening of the electronic expansion valve will decrease, and the greater the temperature difference, the greater the opening adjustment amount. By limiting the pre-output opening of the electronic expansion valve, it is possible to prevent the electronic expansion valve from entering a saturated state during the adjustment process, making the opening adjustment more sensitive and the motor winding temperature control more precise.

[0083] The control unit 104 is further configured to energize the electronic expansion valve in a pulse manner, and control the energization time of the electronic expansion valve according to the operating frequency of the electronic expansion valve, so as to reduce the energization time of the electronic expansion valve and reduce the heat at the electronic expansion valve while making the opening of the electronic expansion valve reach the target opening. The specific functions and processing of the control unit 104 refer to step S130.

[0084] The pulse mode is a power supply mode that provides electrical energy through a periodic pulse signal, and the pulse signal is provided by a pulse generator.

[0085] Figure 6 The flow chart of controlling the opening of the electronic expansion valve is as follows: Figure 6 As shown, the method includes:

[0086] Step 1: upload the temperature of the motor winding to the host computer, and the host computer calculates the preset opening required by the electronic expansion valve according to the temperature of the motor winding.

[0087] Step 2: The host computer controls the electronic expansion valve according to the set action frequency, and performs pulse control according to the set duty cycle, so that the electronic expansion valve reaches a preset opening.

[0088] By controlling the power-on operation of the electronic expansion valve in a pulse manner, the power-on time of each phase coil in the electronic expansion valve is reduced without affecting the operating frequency of the electronic expansion valve, thereby reducing the heat generated by the coil and effectively dissipating the heat at the electronic expansion valve, thereby ensuring the stable operation of the electronic expansion valve and increasing the service life of the electronic expansion valve, avoiding the inability to effectively control the temperature of the motor winding due to failure of the electronic expansion valve, and ensuring the stable operation of the magnetic levitation motor.

[0089] In some embodiments, the control unit 104 controls the power-on time of the electronic expansion valve according to the operating frequency of the electronic expansion valve, including: determining the inverse of the operating frequency of the electronic expansion valve as the pulse period; and taking the result of multiplying the pulse period by a set duty cycle as the power-on time of the electronic expansion valve.

[0090] When controlling the power-on time of the electronic expansion valve, the host computer will first set the operating frequency f of the electronic expansion valve, and calculate the conduction time based on the operating frequency f. The conduction time T = (1 / f) * duty cycle, and the duty cycle is set according to the actual situation. Then, according to the conduction time T, the pulse control method is used to control the conduction time of each phase coil in the electronic expansion valve. Figure 5 As shown in (b), taking the first beat as an example, phase A is energized only part of the time, with a high level when energized and a low level when not energized. The electronic expansion valve works normally when energized, and does not work when not energized. At this time, the coil does not generate heat and will dissipate the accumulated heat. Among them,

[0091] ˉˉ

[0092] As long as the voltages between terminals A, A, B, and B are the same as the voltage between terminals COM, the coil is in a power-off state. For example, if the out1 to out4 terminals of the upper computer control driver chip are all at a high level, the coil can be powered off.

[0093] The pulse control method not only reduces the temperature at the electronic expansion valve, but also does not change the operating frequency of the electronic expansion valve.

[0094] Figure 7 The schematic diagram of the process of controlling the power supply of the electronic expansion valve by pulse mode is as follows:

[0095] Step 11, the host computer sets the operating frequency f of the electronic expansion valve, and calculates the duty cycle time T = (1 / f) * duty cycle, where the duty cycle is the set value.

[0096] Step 12, the host computer controls the driver chip pins in sequence to control the power-on of each phase of the electronic expansion valve. After the power-on time reaches the duty cycle time, the driver chip output is controlled to be high level, so that the electronic expansion valve is powered off.

[0097] Since the processing and functions implemented by the device of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments, and no further elaboration will be made here.

[0098] According to the technical solution of the present invention, an electronic expansion valve is arranged on the coolant pipeline of the motor winding to control the flow of the coolant; after the magnetic levitation motor starts working, the target opening of the electronic expansion valve is determined according to the temperature of the motor winding; the electronic expansion valve is energized in a pulse manner, and the power-on time is controlled according to the operating frequency of the electronic expansion valve, so as to reduce the power-on time of the electronic expansion valve and reduce the heat at the electronic expansion valve while making the electronic expansion valve reach the target opening. By energizing the electronic expansion valve in a pulse manner and controlling the power-on time according to the operating frequency of the electronic expansion valve, the power-on time of the electronic expansion valve is reduced, the heat at the electronic expansion valve is reduced, and the failure of the electronic expansion valve due to high temperature is avoided, so that the temperature of the motor winding is effectively controlled, and the stable operation of the magnetic levitation motor is ensured.

[0099] According to an embodiment of the present invention, a magnetic levitation motor corresponding to a cooling device of the magnetic levitation motor is also provided. The magnetic levitation motor may include: the cooling device of the magnetic levitation motor described above.

[0100] Since the processing and functions implemented by the magnetic levitation motor of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned device, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments, and no further elaboration will be made here.

[0101] According to the technical solution of the present invention, an electronic expansion valve is arranged on the coolant pipeline of the motor winding to control the flow of the coolant; after the magnetic levitation motor starts working, the target opening of the electronic expansion valve is determined according to the temperature of the motor winding; the electronic expansion valve is energized in a pulse manner, and the power-on time is controlled according to the operating frequency of the electronic expansion valve, so as to reduce the power-on time of the electronic expansion valve and reduce the heat at the electronic expansion valve while making the electronic expansion valve reach the target opening. By energizing the electronic expansion valve in a pulse manner and controlling the power-on time according to the operating frequency of the electronic expansion valve, the power-on time of the electronic expansion valve is reduced, the heat at the electronic expansion valve is reduced, and the failure of the electronic expansion valve due to high temperature is avoided, so that the temperature of the motor winding is effectively controlled, and the stable operation of the magnetic levitation motor is ensured.

[0102] According to an embodiment of the present invention, a storage medium corresponding to the cooling method of the magnetic levitation motor is also provided, wherein the storage medium includes a stored program, wherein when the program is run, the device where the storage medium is located is controlled to execute the cooling method of the magnetic levitation motor described above.

[0103] Since the processing and functions implemented by the storage medium of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments, and no further elaboration will be made here.

[0104] According to the technical solution of the present invention, an electronic expansion valve is arranged on the coolant pipeline of the motor winding to control the flow of the coolant; after the magnetic levitation motor starts working, the target opening of the electronic expansion valve is determined according to the temperature of the motor winding; the electronic expansion valve is energized in a pulse manner, and the power-on time is controlled according to the operating frequency of the electronic expansion valve, so as to reduce the power-on time of the electronic expansion valve and reduce the heat at the electronic expansion valve while making the electronic expansion valve reach the target opening. By energizing the electronic expansion valve in a pulse manner and controlling the power-on time according to the operating frequency of the electronic expansion valve, the power-on time of the electronic expansion valve is reduced, the heat at the electronic expansion valve is reduced, and the failure of the electronic expansion valve due to high temperature is avoided, so that the temperature of the motor winding is effectively controlled, and the stable operation of the magnetic levitation motor is ensured.

[0105] According to an embodiment of the present invention, a computer program product corresponding to the cooling method of the magnetic levitation motor is also provided. The computer program product includes a computer program. When the computer program product is processed and executed, the steps of the cooling method of the magnetic levitation motor are implemented.

[0106] Since the processing and functions implemented by the computer program product of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0107] According to the technical solution of the present invention, an electronic expansion valve is arranged on the coolant pipeline of the motor winding to control the flow of the coolant; after the magnetic levitation motor starts working, the target opening of the electronic expansion valve is determined according to the temperature of the motor winding; the electronic expansion valve is energized in a pulse manner, and the power-on time is controlled according to the operating frequency of the electronic expansion valve, so as to reduce the power-on time of the electronic expansion valve and reduce the heat at the electronic expansion valve while making the electronic expansion valve reach the target opening. By energizing the electronic expansion valve in a pulse manner and controlling the power-on time according to the operating frequency of the electronic expansion valve, the power-on time of the electronic expansion valve is reduced, the heat at the electronic expansion valve is reduced, and the failure of the electronic expansion valve due to high temperature is avoided, so that the temperature of the motor winding is effectively controlled, and the stable operation of the magnetic levitation motor is ensured.

[0108] In summary, it is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0109] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A cooling method for a magnetic levitation motor, characterized in that: A coolant pipeline is provided at the motor winding of the magnetic levitation motor; an electronic expansion valve is provided on the coolant pipeline; The method comprises: After the magnetic levitation motor starts to work, obtaining the temperature of the motor winding and the operating frequency of the electronic expansion valve; determining a target opening of the electronic expansion valve according to the temperature of the motor winding; The electronic expansion valve is energized in a pulse manner, and the energization time of the electronic expansion valve is controlled according to the operating frequency of the electronic expansion valve, so as to reduce the energization time of the electronic expansion valve and reduce the heat at the electronic expansion valve while making the opening of the electronic expansion valve reach the target opening.

2. The cooling method of the magnetic levitation motor according to claim 1, characterized in that: The electronic expansion valve comprises a four-phase coil and a valve body; by controlling the power supply of each phase coil of the four-phase coil in sequence according to a set power supply sequence, the valve body is activated to change the opening of the electronic expansion valve so that the electronic expansion valve reaches the target opening.

3. The cooling method of the magnetic levitation motor according to claim 1, characterized in that: Determining a target opening of the electronic expansion valve according to the temperature of the motor winding includes: The temperature of the motor winding is brought into a preset calculation formula to calculate the target opening of the electronic expansion valve; the preset calculation formula is: IN pre-sat =U p (k)+U i (k); Among them, U pre-sat is the target opening of the electronic expansion valve; U p (k) is the proportional output, U p (k) = K p err(k), err(k) = -(Ref - Fdb), Fdb is the temperature of the motor winding, Ref is the reference temperature of the motor winding, K p is the proportional gain coefficient; U i (k) is the integral output.

4. The cooling method of the magnetic levitation motor according to any one of claims 1 to 3, characterized in that: Controlling the power-on time of the electronic expansion valve according to the operating frequency of the electronic expansion valve includes: The inverse of the operating frequency of the electronic expansion valve is determined as the pulse period; The result of multiplying the pulse period by the set duty cycle is used as the power-on time of the electronic expansion valve.

5. A cooling device for a magnetic levitation motor, characterized in that: A coolant pipeline is provided at the motor winding of the magnetic levitation motor; an electronic expansion valve is provided on the coolant pipeline; The cooling device comprises: an acquisition unit, configured to acquire the temperature of the motor winding and the operating frequency of the electronic expansion valve after the magnetic levitation motor starts to work; a control unit configured to determine a target opening of the electronic expansion valve according to a temperature of the motor winding; The control unit is further configured to energize the electronic expansion valve in a pulsed manner, and control the power-on time of the electronic expansion valve according to the operating frequency of the electronic expansion valve, so as to reduce the power-on time of the electronic expansion valve and reduce the heat at the electronic expansion valve while making the opening of the electronic expansion valve reach the target opening.

6. The cooling device for the magnetic levitation motor according to claim 5, characterized in that: The electronic expansion valve comprises a four-phase coil and a valve body; by controlling the power supply of each phase coil of the four-phase coil in sequence according to a set power supply sequence, the valve body is activated to change the opening of the electronic expansion valve so that the electronic expansion valve reaches the target opening.

7. The cooling method of the magnetic levitation motor according to claim 5, characterized in that: The control unit determines the target opening of the electronic expansion valve according to the temperature of the motor winding, including: The temperature of the motor winding is brought into a preset calculation formula to calculate the target opening of the electronic expansion valve; the preset calculation formula is: IN pre-sat =U p (k)+U i (k); Among them, U pre-sat is the target opening of the electronic expansion valve; U p (k) is the proportional output, U p (k) = K p err(k), err(k) = -(Ref - Fdb), Fdb is the temperature of the motor winding, Ref is the reference temperature of the motor winding, K p is the proportional gain coefficient; U i (k) is the integral output.

8. A magnetic levitation motor, characterized in that: include: A cooling device for a magnetic levitation motor as claimed in any one of claims 5 to 7.

9. A storage medium, characterized in that: The storage medium includes a stored program, wherein when the program is executed, the device where the storage medium is located is controlled to execute the cooling method for the magnetic levitation motor according to any one of claims 1 to 4.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

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