Cooling control method and system for laser welding machine

Abstract

The invention belongs to the technical field of cooling control of laser welding machines, and discloses a cooling control method and system of a laser welding machine, an auxiliary expansion valve is arranged in a one-way circulating refrigerating loop and can be matched with a main expansion valve to more accurately adjust the refrigerating capacity, and faster feedback can be obtained by replacing temperature detection with pressure detection. The response speed of the system is improved, calculation is carried out through an estimation model based on the collected first parameter information of the laser welding machine, initial operation parameters of a compressor, a main expansion valve, an auxiliary expansion valve and a fan are obtained, then adjustment is carried out through PID, the situation that a large amount of test experience data is needed and a large amount of time is consumed is avoided, and the system reliability is improved. And the feedback speed and the adjusting speed are also improved, so that higher temperature control precision is realized, the cost is lower, and the adaptability is higher.

Description

Technical Field

[0001] The invention belongs to the technical field of laser welder cooling control, and in particular relates to a laser welder cooling control method and system. Background Art

[0002] The cooling of the laser welding machine is mainly achieved by heating and cooling the refrigeration circuit and controlling the refrigeration circuit to achieve more accurate cooling control. Figure 1 As shown, the single-loop refrigerant refrigeration structure adopted realizes cooling and heating of the cold plate by reversing the four-way valve; when cooling, the heating device on the cold plate generates heat, so that the liquid refrigerant in the cold plate is vaporized and absorbs heat, and the gaseous refrigerant is sucked into the compressor for compression, and the high-temperature and high-pressure gaseous refrigerant is discharged. The high-temperature and high-pressure gaseous refrigerant is cooled into liquid in the condenser, releases heat, and the heat is dissipated into the air. The liquid refrigerant passes through the liquid storage tank, the drying filter, and the electronic expansion valve throttling to control the flow rate and recirculates; when heating, through the reversal of the four-way valve, the refrigerant flow direction is opposite to that of cooling, the condenser becomes the evaporator to absorb heat from the environment, which is the same as the role of the cold plate in refrigeration, the cold plate becomes the condenser, releases heat, and the device absorbs heat, thereby maintaining a certain temperature, which is the same as the role of the condenser in refrigeration.

[0003] But the disadvantages of this circuit are:

[0004] (1) The four-way valve realizes the switching between cooling and heating. It takes a long time for the system to establish a balance. It takes a long time to switch to form a stable heat transfer balance. The state is uncontrollable, which can easily cause the cold plate to overheat or overcool, resulting in the cold plate temperature being out of control;

[0005] (2) When in standby mode, since the compressor is in operation, the heat load on the cold plate is zero, and the cooling capacity is much greater than the heat output, which can easily cause the temperature to be low. When switching to heating mode, the temperature rises rapidly and reaches the set temperature. It takes a certain amount of time to quickly switch back to cooling mode to form a stable refrigeration cycle, which can easily cause the temperature to be high.

[0006] (3) When the heat source on the cold plate is started, the thermal power suddenly changes, the compressor frequency adjustment speed is slow, the heat source temperature rises rapidly, the compressor adjustment speed lags behind the temperature change speed, the temperature quickly overshoots, and when the temperature stops increasing and starts to drop, the cooling capacity is far greater than the heating value, the temperature drops rapidly again, overshooting, resulting in large temperature control fluctuations;

[0007] (4) When the heat source on the cold plate is suddenly turned off, the cooling capacity is much greater than the heating capacity due to the slow frequency adjustment of the compressor, causing the temperature to drop rapidly and the low-temperature overshoot to be serious;

[0008] (5) Poor temperature control accuracy and slow control response.

[0009] For the above-mentioned problems in the refrigeration circuit structure, PID is usually used for regulation and control to reduce the error between the cooling or heating temperature and the target temperature. The PID control of the cooling system mainly includes valve control and fan control. The valve control is based on the feedback control of the evaporator inlet and outlet temperature sensors and the cold plate temperature sensor, and the fan control is based on the condenser temperature feedback control. Conventional cooling system control is mainly achieved through PID control, but when the PID control feedback has a lag or the control variable has a sudden change, it is difficult to achieve accurate control. Moreover, since the temperature sensor is fixed to the outer wall of the copper tube by a clamp, the temperature sensor is required to measure the refrigerant temperature inside the copper tube. The refrigerant temperature must pass through the copper tube wall, the clamp and the temperature sensor shell, and then be transmitted to the temperature sensing chip. There will be a delay in the transmission process, and the sensor is greatly affected by the ambient temperature, resulting in inaccurate test values. The lag and inaccurate temperature values ​​will affect the PID adjustment, forming oscillation and overshoot, and the adjustment speed cannot be fast; at the same time, there is a sudden change in the input heat source of the cooling system, and a few kilowatts of heat load will instantly become zero. The control system cannot complete control in a short time, such as within 10 seconds. The system temperature cannot be controlled and will continue to rise, exceeding the alarm limit. Control cannot be achieved simply through feedback from the system lag. After the feedback is completed, the system temperature has exceeded a lot, and temperature stability cannot be guaranteed.

[0010] There is another way to implement cooling system control, which is fuzzy control + PID adjustment. Fuzzy control is to obtain some empirical values ​​through a large number of experiments. In order to deal with the problem of slow system response, a fuzzy parameter is first output as the initial value of PID parameter control. In order to solve the oscillation caused by the PID adjustment of the lagging system, it is necessary to slow down the speed of PID adjustment. In this way, the control accuracy of the system will be reduced, and the adaptability of the system is weak. Accurate empirical parameters are required, and a lot of time is needed to test the empirical parameters, which greatly prolongs the product development cycle. In addition, in order to solve the problem of delay in temperature detection, fuzzy control is introduced, but fuzzy control requires a lot of experiments and a lot of time to obtain accurate empirical values ​​as the input value of fuzzy control. At the same time, when the system changes slightly, the empirical value will change, and a lot of time is needed to test the empirical value, and the adaptability is weak. After the fuzzy control stage, PID adjustment is entered. Due to the lag in system feedback, the PID adjustment speed is slow, the system response speed is slow, and the control error generated by the system is large, and accurate temperature control cannot be achieved. The temperature control accuracy is > ±3℃.

[0011] Therefore, the problems of unstable cooling and heating, delayed temperature detection and low PID control accuracy in the laser welded refrigeration circuit structure are urgent issues to be solved. Summary of the invention

[0012] In view of this, an object of the present invention is to provide a laser welder cooling control method and system to solve the problems of slow cooling control feedback speed and low control accuracy of the existing laser welder.

[0013] In order to achieve the above object, the present invention adopts the following technical solutions:

[0014] On the one hand, a laser welding machine cooling control method is provided, comprising the following steps:

[0015] The current ambient temperature of the laser welder is obtained, and the initial operating power of the compressor in the refrigeration circuit of the laser welder is determined according to the compressor initial frequency estimation model that matches the relationship between the ambient temperature and the compressor frequency, and the compressor is controlled to operate at the initial operating power; wherein the refrigeration circuit comprises a compressor, a condenser, a main expansion valve and a cooling member that are sequentially connected in series, and an auxiliary expansion valve and a fan for heat dissipation of the condenser are also provided in the refrigeration circuit, the input end of the auxiliary expansion valve is connected to the input end of the condenser, and the output end of the auxiliary expansion valve is connected to the input end of the cooling member;

[0016] Acquire first parameter information of the laser welder, the first parameter information including the pressure at the input end of the condenser and the pressure at the output end of the cooling member, determine a first initial opening of the main expansion valve, a second initial opening of the auxiliary expansion valve, and an initial output ratio of the fan as estimated parameters through an estimation model constructed based on the current ambient temperature of the laser welder and the first parameter information, and control the main expansion valve, the auxiliary expansion valve, and the fan to operate according to the determined estimated parameters;

[0017] Perform PID regulation on the main expansion valve, auxiliary expansion valve and fan.

[0018] In a possible implementation, the first parameter information also includes the current driving voltage of the laser welder, the current driving current, the current laser output power, the current compressor heating power, the current compressor frequency, the condenser input end pressure, the cooling component output end pressure and the compressor heating value;

[0019] The method includes the following steps: determining a first initial opening of a main expansion valve, a second initial opening of an auxiliary expansion valve, and an initial output ratio of a fan as estimation parameters by using an estimation model constructed based on the current ambient temperature of the laser welder and the first parameter information:

[0020] Calculate the first initial opening of the main expansion valve at the current ambient temperature according to the main valve opening estimation model matching the relationship among the main expansion valve flow, the main expansion valve opening and the ambient temperature;

[0021] Calculate the second initial opening of the auxiliary expansion valve at the current compressor frequency according to the auxiliary valve opening model matching the relationship among the compressor frequency, the compressor exhaust volume, the auxiliary expansion valve opening, the unloading flow, the condenser input end pressure and the cooling component output end pressure;

[0022] The initial output ratio of the fan is calculated based on a fan output estimation model that matches the relationship among the driving voltage, driving current, laser output power, compressor heating power and fan output of the laser welder.

[0023] In a possible implementation, the main valve opening estimation model includes the following formula:

[0024] m1=3×L1×n (1)

[0025] In Formula 1, L1 satisfies the following conditions:

[0026] L = 0.5 × T + 26 (2)

[0027] In the above formula, m1 is the first initial opening of the main expansion valve, L1 is the current flow of the main expansion valve, n is the safety factor and the default value is 1.1, and T is the ambient temperature of the laser welder.

[0028] In a possible implementation, the auxiliary valve opening model includes the following conditions:

[0029] L2=(10×V×n) / [(P1 -P2)×5.5] (3)

[0030] In Formula 3, V satisfies the following conditions:

[0031] V=(5.86×60×H) / 1000 (4)

[0032] In the above formula, L2 is the compressor unloading flow, V is the compressor exhaust volume, n is the unloading coefficient, P1 is the condenser input pressure, P2 is the cooling component output pressure, and H is the compressor initial frequency;

[0033] The second initial opening of the auxiliary expansion valve satisfies the following conditions:

[0034] When L2≤1, m2=32×L2;

[0035] When 1<L2≤14.67, m2=24.36×L2+7.64;

[0036] When L2>14.67, m2=2.855×L2+323.19;

[0037] Wherein, m2 is the second initial opening degree of the auxiliary expansion valve.

[0038] In a possible implementation, the fan output estimation model includes the following formula:

[0039] V=(Q1 / 40-3) (5)

[0040] In the above formula, Q1 satisfies the following conditions:

[0041] Q1=U×I-P3+Q2 (6)

[0042] In the above formula, V is the initial output ratio of the fan, Q1 is the heat generated by the condenser, U is the driving voltage of the laser welder, I is the driving current of the laser welder, P3 is the laser output power, and Q2 is the heat generated by the compressor.

[0043] In a possible implementation, the compressor initial frequency estimation model includes the following formula:

[0044] H=0.45×T+31 (7)

[0045] Wherein, H is the initial frequency of the compressor, and T is the ambient temperature of the laser welder.

[0046] In a possible implementation, the pressure at the condenser input end and the pressure at the cooling component output end in the first parameter information are acquired through a pressure sensor.

[0047] In a possible implementation, the condenser is a microchannel condenser.

[0048] On the other hand, a laser welding machine cooling control system is also provided, comprising:

[0049] A refrigeration circuit comprises a compressor, a condenser, a main expansion valve and a cooling member which are sequentially connected in series. An auxiliary expansion valve and a fan for heat dissipation of the condenser are also arranged in the refrigeration circuit. The input end of the auxiliary expansion valve is connected to the input end of the condenser, and the output end of the auxiliary expansion valve is connected to the input end of the cooling member.

[0050] A first parameter acquisition module, used to acquire first parameter data including ambient temperature, condenser input end pressure and cooling component output end pressure; and

[0051] The controller includes an estimation model calculation module, a PID adjustment module and a control operation module, wherein the estimation model calculation module is used to calculate a first initial opening of a main expansion valve, a second initial opening of an auxiliary expansion valve and an initial output ratio of a fan according to first parameter data, the control operation module is used to control the main expansion valve, the auxiliary expansion valve and the fan to operate with corresponding estimation parameters calculated by the estimation model calculation module, and the PID adjustment module is used to perform PID algorithm adjustment when the main expansion valve, the auxiliary expansion valve and the fan operate with corresponding estimation parameters.

[0052] In a possible implementation, the condenser is a microchannel condenser;

[0053] And / or, the first parameter acquisition module includes a temperature sensor for acquiring ambient light temperature, a pressure sensor 1 for acquiring pressure at the input end of the condenser, and a pressure sensor 2 for acquiring pressure at the output end of the cooling component.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] The laser welder cooling control method and system of the present invention can cooperate with the main expansion valve to more accurately adjust the refrigeration capacity by setting an auxiliary expansion valve in a unidirectional circulation refrigeration circuit, and can obtain faster feedback by replacing temperature detection with pressure detection, thereby improving the response speed of the system. The initial operating parameters of the compressor, the main expansion valve, the auxiliary expansion valve and the fan are calculated based on the collected first parameter information of the laser welder through an estimation model, and then PID is entered for adjustment, which not only avoids the need for a large amount of test experience data and a large amount of time, but also improves the feedback speed and the adjustment speed, thereby achieving higher temperature control accuracy, lower cost and stronger adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic diagram of an existing single-circuit refrigerant refrigeration structure;

[0057] Figure 2 It is a schematic diagram of the refrigeration circuit structure of a laser welding machine cooling control method;

[0058] Figure 3 The present invention is a flow chart of a cooling control method for a laser welder. DETAILED DESCRIPTION

[0059] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with specific implementation methods.

[0060] Please refer to Figure 2 and Figure 3 As shown, the embodiment of the present application provides a laser welding machine cooling control method, comprising the following steps:

[0061] Step S100: Acquire the current ambient temperature of the laser welder, and determine the initial operating power of the compressor in the refrigeration circuit of the laser welder according to the compressor initial frequency estimation model that matches the relationship between the ambient temperature and the compressor frequency, and control the compressor to operate at the initial operating power; wherein the refrigeration circuit includes a compressor, a condenser, a main expansion valve and a cooling component arranged in series in sequence, and an auxiliary expansion valve and a fan for heat dissipation of the condenser are also arranged in the refrigeration circuit, the input end of the auxiliary expansion valve is connected to the input end of the condenser, and the output end of the auxiliary expansion valve is connected to the input end of the cooling component.

[0062] In this step, the refrigeration circuit used by the laser welder is a one-way circulation refrigeration circuit. The compressor, condenser, main electronic expansion valve, auxiliary electronic expansion valve, and cooling component of the refrigeration circuit are connected by copper pipes. The cooling component can be a cold plate used to cool the heating device. The heat of the heating device is transferred to the refrigerant through the cold plate. The refrigerant absorbs heat by evaporation. The gas generated by evaporation is compressed by the compressor to become high-pressure gas and circulate to the condenser. The heat of the gas is transferred to the condenser fins. The fan forces air to flow through the microchannel condenser fins to take away the heat on the fins, causing the refrigerant to condense, and then circulate to the cold plate through the main electronic expansion valve to form a cycle. The auxiliary electronic expansion valve in parallel can adjust the refrigeration capacity of the high-pressure refrigerant, and the main expansion valve can be adjusted more accurately. In addition, through such a one-way circulation refrigeration structure, the refrigeration effect is more stable and the error is smaller. By constructing a compressor initial frequency estimation model that matches the relationship between ambient temperature and compressor frequency, where the relationship between ambient temperature and compressor frequency is a linear relationship, an estimated parameter can be calculated through the constructed compressor initial frequency estimation model and used as the initial operating power of the compressor. In this way, the compressor can operate with an estimated parameter that conforms to the operating law of the compressor, and this estimated parameter can be closer to the accurate operating parameter, which can more accurately and directly achieve the purpose of reducing the error, and on this basis, PID adjustment and control can be performed to make the system respond faster and the control more precise.

[0063] Step S200: Obtain the first parameter information of the laser welder, the first parameter information including the pressure at the condenser input end and the pressure at the cooling component output end, and determine the first initial opening of the main expansion valve, the second initial opening of the auxiliary expansion valve and the initial output ratio of the fan as estimated parameters through an estimation model constructed based on the current ambient temperature of the laser welder and the first parameter information, and control the main expansion valve, the auxiliary expansion valve and the fan to operate according to the determined estimated parameters.

[0064] In this step, the temperature control of the cooling component is achieved by controlling the evaporation pressure. By collecting the pressure data at the output end of the cooling component in real time and adjusting the control of the expansion valve phenomenon pressure, the pressure response is faster, which can greatly improve the response speed of the system. The temperature control of the condenser is achieved by adjusting the fan speed by collecting the pressure data in the input end of the condenser in real time to achieve condensation temperature control. The pressure response is faster, which can greatly improve the response speed of the system. The traditional refrigeration system collects the temperature of the cold plate and condenser through the temperature sensor, adjusts the electronic expansion valve, and realizes the temperature adjustment of the cold plate. When the temperature sensor detects, the heat is first transferred to the surface of the copper tube, and then transferred to the temperature sensor probe through the temperature sensor fixture. The transfer time is long and the reaction speed is slow. In addition, the temperature sensor will also be affected by the ambient temperature, resulting in acquisition errors and reducing the control accuracy. Therefore, the feedback is more direct and fast, which can avoid the induction delay caused by the temperature sensor installed with a fixture outside the copper tube of the pipeline, and can effectively reduce the error and improve the control accuracy.

[0065] Moreover, based on the collected first parameter information and ambient temperature, an estimation model is constructed about the first initial opening of the main expansion valve, the second initial opening of the auxiliary expansion valve and the initial output ratio of the fan, and the corresponding estimation parameters can be determined through the estimation model to achieve coarse adjustment, avoiding a lot of time spent on testing a large amount of empirical data. After coarse adjustment, PID adjustment is entered. Since the pressure sensor has a faster feedback speed, real-time feedback can be provided to achieve rapid PID adjustment and higher temperature control accuracy.

[0066] Step S300: Perform PID adjustment on the main expansion valve, the auxiliary expansion valve and the fan.

[0067] In this step, PID regulation can combine the control effects of proportional control, integral control and differential control in the refrigeration circuit to achieve precise control of the system, and can optimize the control effect by adjusting the three parameters of proportional, integral and differential according to the specific needs and characteristics of the system. After obtaining the basic estimated parameters of the main expansion valve, auxiliary expansion valve and fan, PID regulation can make the regulation more precise and achieve higher temperature control accuracy.

[0068] In one embodiment, the first parameter information also includes the current driving voltage of the laser welder, the current driving current, the current laser output power, the current compressor heating power, the current compressor frequency, the condenser input end pressure, the cooling component output end pressure and the compressor heating value;

[0069] The method includes the following steps: determining a first initial opening of a main expansion valve, a second initial opening of an auxiliary expansion valve, and an initial output ratio of a fan as estimation parameters by using an estimation model constructed based on the current ambient temperature of the laser welder and the first parameter information:

[0070] Step S201: Calculate a first initial opening of the main expansion valve at the current ambient temperature according to a main valve opening estimation model that matches the relationship among the main expansion valve flow rate, the main expansion valve opening and the ambient temperature.

[0071] Step S202: Calculate the second initial opening of the auxiliary expansion valve at the current compressor frequency according to the auxiliary valve opening model that matches the relationship between the compressor frequency, the compressor exhaust volume, the auxiliary expansion valve opening, the unloading flow, the condenser input end pressure and the cooling component output end pressure;

[0072] Step S203: Calculate the initial output ratio of the fan according to a fan output estimation model that matches the relationship between the driving voltage, driving current, laser output power, compressor heating power and fan output of the laser welder.

[0073] In this way, the main valve opening estimation model, auxiliary valve opening model and fan output estimation model, which are constructed through the relationship or rules between each parameter and the target parameter, can respectively determine the first initial opening of the main expansion valve at the current ambient temperature, the second initial opening of the auxiliary expansion valve at the current compressor frequency, and the initial output ratio of the fan, thereby obtaining the corresponding estimation parameters and avoiding the need to obtain initial values ​​through a large number of experiments that consume a lot of energy and time.

[0074] Regarding the construction of the main valve opening estimation model, in a preferred embodiment, the flow through the main expansion valve is calculated according to the ambient temperature, the flow and the valve opening are linearized as shown in Table 1, and the opening of the main expansion valve is calculated.

[0075] Table 1

[0076] Serial number Ambient temperature / ℃ Main valve flow / kg / h 1 10 31 2 20 36 3 30 41 4 40 46 5 50 51

[0077] The ambient temperature and main valve flow are linearized to obtain the formula: L1 = 0.5 × T + 26, where L1 is the current flow of the main expansion valve and T is the ambient temperature of the laser welder. Then, the main electronic expansion valve opening is calculated according to the valve characteristics, and the main valve flow and valve opening are linearized to obtain the formula: m1 = 3 × L1 × n, where m1 is the first initial opening of the main expansion valve, L1 is the current flow of the main expansion valve, and n is the safety factor and is 1.1 by default.

[0078] When the first initial opening of the main expansion valve is calculated, the main expansion valve is immediately adjusted to the first initial opening, and then PID regulation is entered.

[0079] Regarding the construction of the auxiliary valve opening model, in a preferred embodiment, the compressor exhaust volume is calculated based on the compressor initial frequency, and the calculation formula is: V = (5.86×60×H) / 1000, where V is the compressor exhaust volume and H is the compressor initial frequency.

[0080] Then, according to the compressor exhaust volume and unloading coefficient, the compressor unloading flow is calculated, and the calculation formula is: L2 = (10×V×n) / [(P1-P2)×5.5], where L2 is the compressor unloading flow, V is the compressor exhaust volume, n is the unloading coefficient, P1 is the condenser input pressure, P2 is the cooling component output pressure, and H is the compressor initial frequency.

[0081] According to the relationship between the unloading flow and the auxiliary valve opening, the unloading flow and the auxiliary valve opening are linearized to obtain:

[0082] The second initial opening of the auxiliary expansion valve meets the following conditions:

[0083] When L2≤1, m2=32×L2;

[0084] When 1<L2≤14.67, m2=24.36×L2+7.64;

[0085] When L2>14.67, m2=2.855×L2+323.19;

[0086] Wherein, m2 is the second initial opening degree of the auxiliary expansion valve.

[0087] Therefore, by using such a construction method, it is possible to obtain an auxiliary valve opening degree model that can calculate the second initial opening degree of the auxiliary expansion valve.

[0088] Regarding the fan output estimation model, in a preferred embodiment, the control system collects the driving voltage, driving current and laser output power of the laser welder and the heating power of the compressor to calculate the heating value of the condenser. The calculation formula is: Q1=U×I-P3+Q2, wherein Q1 is the heating value of the condenser, U is the driving voltage of the laser welder, I is the driving current of the laser welder, P3 is the laser output power, and Q2 is the heating value of the compressor.

[0089] Then, according to the approximate linear relationship between the heat output and the fan percentage, the heat output and the fan percentage are linearized, as shown in Table 2, and the formula is obtained: V = (Q1 / 40-3), where V is the initial output ratio of the fan and Q1 is the heat output of the condenser.

[0090] Table 2

[0091] Serial number Heat generation / W Fan output percentage / % 1 3500 85 2 2500 60 3 1500 35 4 500 10

[0092] The fan output estimation model can be obtained by the above method, and the fan output percentage can be calculated by the model.

[0093] Regarding the compressor initial frequency estimation model, in a preferred embodiment, the compressor operating frequency is calculated according to the ambient temperature and adjusted to the corresponding frequency.

[0094] Since the heat source power does not change with temperature, the cooling capacity is required to be about 3000W. The compressor cooling capacity changes with temperature as shown in Table 3. From Table 3, it can be seen that the compressor frequency and the ambient temperature have an approximately linear relationship. The ambient temperature and the compressor frequency are linearized to obtain the formula: H = 0.45 × T + 31, where H is the initial frequency of the compressor and T is the ambient temperature of the laser welder.

[0095] Table 3

[0096] Serial number Ambient temperature / ℃ Compressor frequency / Hz Cooling capacity / W 1 10 36 3000 2 20 40 3020 3 30 45 2980 4 40 49 3100 5 50 54 3060

[0097] Through the above estimation model construction method, the compressor initial frequency estimation model can be obtained.

[0098] Furthermore, the condenser input pressure and the cooling component output pressure in the first parameter information are acquired through a pressure sensor. By acquiring the condenser input pressure and the cooling component output pressure through a pressure sensor, the pressure response is faster, which can greatly improve the response speed of the system.

[0099] In order to further improve the hardware response speed, further, the condenser adopts a microchannel condenser.

[0100] Therefore, the above-mentioned laser welding machine cooling control method can have the following technical effects:

[0101] (1) Using mathematical models to calculate and obtain initial values ​​avoids the need to spend a lot of time and energy on a large number of experiments. This is more flexible, less costly, more accurate, and more adaptable.

[0102] (2) Use microchannel condensers and pressure sensors to improve system response speed;

[0103] (3) As the hardware improves the system response speed, the software can increase the refresh speed, further improving the temperature control accuracy.

[0104] The embodiment of the present application also provides a laser welding machine cooling control system, including:

[0105] A refrigeration circuit comprises a compressor, a condenser, a main expansion valve and a cooling member which are sequentially connected in series. An auxiliary expansion valve and a fan for heat dissipation of the condenser are also arranged in the refrigeration circuit. The input end of the auxiliary expansion valve is connected to the input end of the condenser, and the output end of the auxiliary expansion valve is connected to the input end of the cooling member.

[0106] A first parameter acquisition module, used to acquire first parameter data including ambient temperature, condenser input end pressure and cooling component output end pressure; and

[0107] The controller includes an estimation model calculation module, a PID adjustment module and a control operation module, wherein the estimation model calculation module is used to calculate a first initial opening of a main expansion valve, a second initial opening of an auxiliary expansion valve and an initial output ratio of a fan according to first parameter data, the control operation module is used to control the main expansion valve, the auxiliary expansion valve and the fan to operate with corresponding estimation parameters calculated by the estimation model calculation module, and the PID adjustment module is used to perform PID algorithm adjustment when the main expansion valve, the auxiliary expansion valve and the fan operate with corresponding estimation parameters.

[0108] The condenser is a microchannel condenser; and / or, the first parameter acquisition module includes a temperature sensor for collecting ambient light temperature, a pressure sensor P1 for collecting the pressure at the input end of the condenser, and a pressure sensor P2 for collecting the pressure at the output end of the cooling component.

[0109] Specifically, the laser welder is a handheld laser welder.

[0110] In summary, the laser welder cooling control method and system of the embodiment of the present application, by setting an auxiliary expansion valve in the unidirectional circulation refrigeration circuit, can cooperate with the main expansion valve to more accurately adjust the refrigeration capacity, and can obtain faster feedback by replacing temperature detection with pressure detection, thereby improving the response speed of the system, and based on the collected first parameter information of the laser welder, the estimation model is used to calculate and obtain the initial operating parameters of the compressor, the main expansion valve, the auxiliary expansion valve and the fan, and then enter the PID for adjustment, which not only avoids the need for a large amount of test experience data and a lot of time, but also improves the feedback speed and the adjustment speed, thereby achieving higher temperature control accuracy, lower cost and stronger adaptability.

[0111] The above are only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A laser welding machine cooling control method, characterized in that: The following steps are involved: The current ambient temperature of the laser welder is obtained, and the initial operating power of the compressor in the refrigeration circuit of the laser welder is determined according to the compressor initial frequency estimation model that matches the relationship between the ambient temperature and the compressor frequency, and the compressor is controlled to operate at the initial operating power; wherein the refrigeration circuit comprises a compressor, a condenser, a main expansion valve and a cooling member that are sequentially connected in series, and an auxiliary expansion valve and a fan for heat dissipation of the condenser are also provided in the refrigeration circuit, the input end of the auxiliary expansion valve is connected to the input end of the condenser, and the output end of the auxiliary expansion valve is connected to the input end of the cooling member; Acquire first parameter information of the laser welder, the first parameter information including the pressure at the input end of the condenser and the pressure at the output end of the cooling member, determine a first initial opening of the main expansion valve, a second initial opening of the auxiliary expansion valve, and an initial output ratio of the fan as estimated parameters through an estimation model constructed based on the current ambient temperature of the laser welder and the first parameter information, and control the main expansion valve, the auxiliary expansion valve, and the fan to operate according to the determined estimated parameters; Perform PID regulation on the main expansion valve, auxiliary expansion valve and fan.

2. A laser welding machine cooling control method as claimed in claim 1, characterized in that: The first parameter information also includes the current driving voltage of the laser welder, the current driving current, the current laser output power, the current compressor heating power, the current compressor frequency, the condenser input end pressure, the cooling component output end pressure and the compressor heating value; The first initial opening of the main expansion valve, the second initial opening of the auxiliary expansion valve and the initial output ratio of the fan as estimation parameters are determined respectively by an estimation model constructed based on the current ambient temperature of the laser welder and the first parameter information, including the following methods: Calculate the first initial opening of the main expansion valve at the current ambient temperature according to the main valve opening estimation model matching the relationship among the main expansion valve flow, the main expansion valve opening and the ambient temperature; Calculate the second initial opening of the auxiliary expansion valve at the current compressor frequency according to the auxiliary valve opening model matching the relationship among the compressor frequency, the compressor exhaust volume, the auxiliary expansion valve opening, the unloading flow, the condenser input end pressure and the cooling component output end pressure; The initial output ratio of the fan is calculated based on a fan output estimation model that matches the relationship among the driving voltage, driving current, laser output power, compressor heating power and fan output of the laser welder.

3. A laser welding machine cooling control method as claimed in claim 2, characterized in that: The main valve opening estimation model includes the following formula: m1=3×L1×n (1) In Formula 1, L1 satisfies the following conditions: L1 = 0.5 × T + 26 (2) In the above formula, m1 is the first initial opening of the main expansion valve, L1 is the current flow of the main expansion valve, n is the safety factor and the default value is 1.1, and T is the ambient temperature of the laser welder.

4. A laser welding machine cooling control method as claimed in claim 2, characterized in that: The auxiliary valve opening model includes the following conditions: L2=(10×V×n) / [(P1 -P2)×5.5] (3) In Formula 3, V satisfies the following conditions: V=(5.86×60×H) / 1000 (4) In the above formula, L2 is the compressor unloading flow, V is the compressor exhaust volume, n is the unloading coefficient, P1 is the condenser input pressure, P2 is the cooling component output pressure, and H is the compressor initial frequency; The second initial opening of the auxiliary expansion valve satisfies the following conditions: When L2≤1, m2=32×L2; When 1<L2≤14.67, m2=24.36×L2+7.64; When L2>14.67, m2=2.855×L2+323.19; Wherein, m2 is the second initial opening degree of the auxiliary expansion valve.

5. A laser welding machine cooling control method as claimed in claim 2, characterized in that: The fan output estimation model includes the following formula: V=(Q1 / 40-3) (5) In the above formula, Q1 satisfies the following conditions: Q1=U×I-P3+Q2 (6) In the above formula, V is the initial output ratio of the fan, Q1 is the heat generated by the condenser, U is the driving voltage of the laser welder, I is the driving current of the laser welder, P3 is the laser output power, and Q2 is the heat generated by the compressor.

6. A laser welding machine cooling control method as claimed in claim 1, characterized in that: The compressor initial frequency estimation model includes the following formula: H=0.45×T+31 (7) Wherein, H is the initial frequency of the compressor, and T is the ambient temperature of the laser welder.

7. A laser welding machine cooling control method as claimed in claim 1, characterized in that: The pressure at the condenser input end and the pressure at the cooling component output end in the first parameter information are acquired through a pressure sensor.

8. A laser welding machine cooling control method as claimed in claim 1, characterized in that: The condenser is a microchannel condenser.

9. A laser welding machine cooling control system, characterized in that: include: A refrigeration circuit comprises a compressor, a condenser, a main expansion valve and a cooling member which are sequentially connected in series. An auxiliary expansion valve and a fan for heat dissipation of the condenser are also arranged in the refrigeration circuit. The input end of the auxiliary expansion valve is connected to the input end of the condenser, and the output end of the auxiliary expansion valve is connected to the input end of the cooling member. A first parameter acquisition module, used to acquire first parameter data including ambient temperature, condenser input end pressure and cooling component output end pressure; as well as The controller includes an estimation model calculation module, a PID adjustment module and a control operation module, wherein the estimation model calculation module is used to calculate a first initial opening of a main expansion valve, a second initial opening of an auxiliary expansion valve and an initial output ratio of a fan according to first parameter data, the control operation module is used to control the main expansion valve, the auxiliary expansion valve and the fan to operate with corresponding estimation parameters calculated by the estimation model calculation module, and the PID adjustment module is used to perform PID algorithm adjustment when the main expansion valve, the auxiliary expansion valve and the fan operate with corresponding estimation parameters.

10. A laser welding machine cooling control system as claimed in claim 9, characterized in that: The condenser is a microchannel condenser; And / or, the first parameter acquisition module includes a temperature sensor for acquiring ambient light temperature, a pressure sensor 1 for acquiring pressure at the input end of the condenser, and a pressure sensor 2 for acquiring pressure at the output end of the cooling component.

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