Control method of oil cooling motor system

Abstract

The invention discloses a control method of an oil cooling motor system. The control method comprises the following steps: S1, inputting a target rotating speed, a torque and main motor parameters of a main motor; s2, estimating main motor bearing loss, main motor iron loss, main motor copper loss and wind abrasion according to the input data, and summing all the losses; s3, calculating the oil quantity required by the system, calculating the rotating speed of an oil pump according to the oil quantity, and judging whether the rotating speed of the oil pump is higher than the maximum allowable rotating speed or not; s4, when the oil temperature reaches a set value of a radiator temperature control three-way valve, the lubricating oil passes through a radiator; s5, when the temperature of the stator reaches a set value of the stator temperature control three-way valve, the lubricating oil passes through the stator; and S6, the lubricating oil in the stator converges at the stator temperature control three-way valve through a pipeline and then reaches the bearing through a filter, and the lubricating oil after cooling the bearing returns to the oil tank. According to the method, the system flow resistance can be remarkably reduced, and meanwhile the oil supply temperature of the system can be stabilized.

Description

Technical Field

[0001] The present invention relates to the technical field of motors and new energy vehicles, and in particular to a control method for an oil-cooled motor system. Background Art

[0002] Oil-cooled motors are emerging with new energy vehicles. Oil cooling is one of the main cooling forms for medium and low voltage motors and new energy vehicle motors. Oil-cooled motors can significantly reduce the temperature rise of windings because the cooling oil is in direct contact with the windings of the motor's heating components. However, the viscosity of the cooling oil is exponentially related to the temperature. Under low temperature conditions, the viscosity of the oil is extremely high (the viscosity of the oil at 5°C is dozens of times that of 40°C), requiring the oil pump to have a very large torque, but the oil pump drive motor may burn out or the oil system may leak due to excessive pressure. After calculating the lubrication system, it was found that the flow resistance and pressure resistance weaknesses of the lubrication system mainly exist in the heat exchange components, namely the heat exchanger and the oil-cooled motor stator, while the flow resistance of the pipeline itself is very small, and the risk of leakage is also low. The existing solutions mainly use the control of the oil pump speed to match the motor operation mode, without a decompression method, and a small part of monitoring the oil pressure, that is, reducing the oil pump speed when the system is over-pressured, but this may cause insufficient lubricating oil supply, and the risk of over-temperature of the bearings or motor windings. The existing oil cooling system generally adopts the "oil-water-air" cooling solution, which undergoes two layers of heat exchange, but the system response speed is slow and the efficiency is low.

[0003] An existing generator set supported by sliding bearings has a large demand for lubricating oil. At the same time, the unit is required to be suitable for desert or plateau environments. The system is required to be extremely compact. In order to improve the heat exchange efficiency and reduce the size of the motor, the motor adopts an oil cooling solution. Using the traditional method, the system flow resistance is too large at low temperatures. When the target flow rate is to be reached, the oil pump cannot be started. In the traditional method, the oil system uses a water cooling method. Due to the two heat exchanges of oil-water-air, the target oil temperature cannot be reached in high temperature weather environments. Using Freon refrigeration will increase the complexity of the system and reduce the system reliability.

[0004] The existing patent application number CN202210727136.7 discloses an oil cooling circuit control method, system and electric vehicle for an oil-cooled motor system, which determines the current flow resistance of the oil cooling circuit according to the oil temperature, oil pump operating current and oil pump speed, and judges whether the oil cooling circuit has an abnormal state by judging whether the current flow resistance of the oil cooling circuit is within a preset theoretical flow resistance range. If the oil cooling circuit has an abnormal state, the lubricating oil flow rate of the oil cooling circuit is increased by increasing the oil pump speed, thereby providing the lubricating oil flow rate required for cooling and lubrication of the oil-cooled motor system. This invention only controls the flow rate by controlling the speed of the lubricating oil pump, there is no system decompression, and the oil temperature cannot be accurately controlled. The existing patent application number CN201910636889.5 discloses an oil-cooled motor control device and method, and the oil-cooled motor temperature control method described in the patent includes: controlling the speed of the oil pump according to the predicted working condition of the oil-cooled motor, the temperature control target of the oil-cooled motor, and the temperature control target of the lubricating oil; controlling the speed of the water pump according to the temperature of the coolant flowing into the heat exchanger, the temperature of the lubricating oil in the oil sump, the flow rate of the lubricating oil, and the temperature control target of the lubricating oil. This control method has too many input variables, resulting in an overly complex system, and there is a coupling relationship between the input variables, and the control target does not explain the basis for determination. The existing patent application number CN202210434619.8 discloses an oil pump control method, system and vehicle for an oil-cooled motor system. The working mode of the invention selects the oil pump speed to match the motor operation mode, but when the oil temperature is low and the motor starts with a large torque, the viscosity of the lubricating oil is high, the system flow resistance is large, the system oil pressure is high, and the oil pump system has a risk of leakage, and no method for reducing the flow resistance and controlling the oil temperature is provided. Summary of the invention

[0005] The present invention is mainly aimed at various lubrication systems and oil-cooled motor solutions in the prior art, which do not involve methods for reducing drag and controlling target temperature. When starting at low temperature, the system pressure is too high, and there is a risk of excessive oil pump power and leakage. When the bearing lubricating oil temperature fluctuates too much, it may cause the bearing oil film to be unstable, causing abnormal vibration or abnormal noise of the unit. A control method for an oil-cooled motor system is proposed.

[0006] In view of the above technical problems, the technical solutions of the present invention are as follows:

[0007] A control method for an oil-cooled motor system comprises the following steps:

[0008] S1, input the target speed, torque and parameters of the main motor;

[0009] S2, estimating the main motor bearing loss, main motor iron loss, main motor copper loss and wind wear according to the data input in step S1, and then summing the main motor bearing loss, main motor iron loss, main motor copper loss and wind wear;

[0010] S3, calculating the amount of oil required by the oil-cooled motor system, calculating the oil pump speed according to the oil amount, and judging whether the oil pump speed is higher than the maximum allowable speed. When the oil pump speed is lower than the maximum allowable speed, the motor runs at a given speed; when the oil pump speed is higher than the maximum allowable speed, the motor runs at the maximum speed;

[0011] S4. A temperature sensor is provided on the radiator bypass pipeline, and the temperature sensor detects the temperature of the lubricating oil after the radiator temperature control three-way valve converges. When the oil temperature reaches the set value of the radiator temperature control three-way valve, the radiator temperature control three-way valve opens, and part or all of the lubricating oil passes through the radiator;

[0012] S5, the stator winding is connected to the stator winding temperature sensor, and the stator winding temperature sensor is connected to the stator temperature control three-way valve. When the stator temperature reaches the set value of the stator temperature control three-way valve, the stator temperature control three-way valve is opened, and part or all of the lubricating oil passes through the stator;

[0013] S6. The lubricating oil in the stator is converged at the stator temperature control three-way valve through a pipeline. The converged lubricating oil passes through a filter to remove impurities in the lubricating oil and then supplies oil to the motor bearings. The lubricating oil after cooling the bearings returns to the oil tank.

[0014] Furthermore, the temperature control target of the radiator temperature control three-way valve is the temperature of the lubricating oil after confluence, and the temperature control target of the stator temperature control three-way valve is the temperature of the stator winding.

[0015] Furthermore, in step S4, when the oil temperature of the lubricating oil is lower than the set value of the radiator temperature control three-way valve, the lubricating oil reaches the radiator temperature control three-way valve through the radiator bypass oil pipe.

[0016] Furthermore, in step S4, if the oil temperature of the lubricating oil after confluence of the radiator temperature control three-way valve is higher than the target temperature, the radiator fan is turned on; if the oil temperature of the lubricating oil after confluence of the radiator temperature control three-way valve is lower than the target temperature, the radiator fan is braked.

[0017] Furthermore, the target temperature after confluence at the radiator adjusts the flow ratio through the radiator and the bypass pipe to balance the overall oil supply temperature of the system. When the oil temperature after confluence is high, all the lubricating oil passes through the radiator. When the oil temperature after confluence is low, all the lubricating oil passes through the radiator bypass pipe.

[0018] Furthermore, the speed of the radiator fan is determined according to the temperature of the converged lubricating oil. When the oil temperature deviates from the target temperature, the speed of the radiator fan increases. Conversely, the speed of the radiator fan decreases until it stops.

[0019] Furthermore, in step S5, the stator temperature is detected by the stator winding temperature sensor. When the stator temperature is too high, the oil pump speed is increased and the process returns to step S3; when the stator temperature is within a normal range, the oil pump maintains the predetermined speed.

[0020] Furthermore, in step S5, the stator temperature is detected by the stator winding temperature sensor. When the stator temperature is lower than the set value of the stator temperature control three-way valve, the lubricating oil directly reaches the filter through the stator bypass pipeline and reaches the bearing through the filter.

[0021] Furthermore, a bearing oil inlet temperature sensor is provided on the bearing oil inlet line, and the bearing temperature is detected by the bearing oil inlet temperature sensor. If the bearing temperature is too high, the oil pump speed is increased and returns to step S3; if the bearing temperature is within a normal range, the oil pump maintains a predetermined speed.

[0022] Furthermore, the flow rate through the stator winding is determined by the stator. When the stator winding temperature sensor detects that the stator temperature is high, the oil pump controls the flow rate of the lubricating oil through the stator to be large; when the stator winding temperature sensor detects that the stator temperature is low, the oil pump controls the flow rate of the lubricating oil through the stator to be small.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention cools the radiator through a bypass oil pipe or an electric fan, then converges at the radiator temperature control three-way valve, passes through the motor stator or the stator bypass oil pipe, and converges again at the stator temperature control three-way valve. The lubricating oil after convergence passes through a filter to remove impurities in the lubricating oil and then supplies oil to the motor bearing. The lubricating oil after cooling the bearing will be returned to the oil tank through gravity or an oil return pump. The radiator 3 fan and oil pump have variable speeds, the radiator temperature control three-way valve controls the target temperature to be the temperature after convergence, and the stator temperature control three-way valve controls the target temperature to be the stator winding temperature. The lubricating oil flow resistance is adjusted by the radiator temperature control three-way valve and the stator temperature control three-way valve. When the system oil temperature is low, the lubricating oil passes through the bypass pipeline, which can significantly reduce the system flow resistance and reduce the oil pump power; the oil pump speed matches the target speed or stator loss, and the oil pump speed is adjusted in real time according to the loss to reduce the power consumption of the oil pump during the entire working cycle.

[0025] 2. The oil temperature control method provided by the present invention maintains a stable oil inlet temperature through the coordination of two-way temperature control three-way valves and two-stage speed of the heat exchanger fan.

[0026] 3. Use air-oil cooling for direct heat exchange cooling, reduce the intermediate link of cooling water, increase the temperature difference between heat exchange media, significantly improve the efficiency of heat exchanger, reduce the size of heat exchanger, and improve system reliability; because the system does not require cooling water, it can be used in water-scarce environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flow chart of temperature and pressure control of lubrication system of oil-cooled motor system;

[0028] Figure 2 It is a schematic diagram of the lubrication system of an oil-cooled motor;

[0029] Figure 3 Provides control logic diagram for oil cooling radiator fan operation;

[0030] Figure 4 The following is a schematic diagram of another system for an oil-cooled motor lubrication system.

[0031] In the figure, 1. mailbox; 2. oil pump; 3. radiator; 4. radiator temperature control three-way valve; 5. stator temperature control three-way valve; 6. filter; 7. stator; 8. stator winding temperature sensor; 9. bearing oil inlet temperature sensor; 10. bearing; 11. main motor; 12. radiator bypass pipeline; 13. stator bypass pipeline; 14. temperature sensor. DETAILED DESCRIPTION

[0032] In order to clearly illustrate the technical features of the application scheme of the present invention, the present invention is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0033] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0034] Example 1

[0035] like Figure 1 and Figure 2 As shown, a control method for an oil-cooled motor system comprises the following steps:

[0036] S1, input the target speed, torque and parameters of the main motor 11;

[0037] S2, estimating the main motor bearing loss, main motor iron loss, main motor copper loss and wind wear according to the data input in step S1, and then summing the main motor bearing loss, main motor iron loss, main motor copper loss and wind wear;

[0038] S3, calculating the amount of oil required by the oil-cooled motor system, calculating the speed of the oil pump 2 according to the amount of oil, and judging whether the speed of the oil pump 2 is higher than the maximum allowable speed. When the speed of the oil pump 2 is lower than the maximum allowable speed, the main motor 11 runs at a given speed; when the speed of the oil pump 2 is higher than the maximum allowable speed, the main motor 11 runs at the maximum speed;

[0039] S4, a temperature sensor 14 is provided on the radiator bypass pipe 12, and the temperature sensor 14 detects the temperature of the lubricating oil after confluence with the radiator temperature control three-way valve 4. When the oil temperature reaches the set value of the radiator temperature control three-way valve 4, the radiator temperature control three-way valve 4 is opened, and part or all of the lubricating oil passes through the radiator 3;

[0040] S5, the stator 7 winding is connected to the stator winding temperature sensor 8, and the stator winding temperature sensor 8 is connected to the stator temperature control three-way valve 5. When the temperature of the stator 7 reaches the set value of the stator temperature control three-way valve 5, the stator temperature control three-way valve 5 is opened, and part or all of the lubricating oil passes through the stator 7;

[0041] S6, the lubricating oil in the stator 7 is converged at the stator temperature control three-way valve 5 through the pipeline, and the converged lubricating oil passes through the filter 6 to remove impurities in the lubricating oil and then supplies oil to the bearing 10. The lubricating oil after cooling the bearing 10 returns to the oil tank 1.

[0042] like Figure 1 As shown, the temperature control target of the radiator temperature control three-way valve 4 is the temperature of the lubricating oil after confluence, and the temperature control target of the stator temperature control three-way valve 5 is the temperature of the stator 7 winding. In step S4, when the temperature of the lubricating oil is lower than the set value of the radiator temperature control three-way valve 4, the lubricating oil reaches the radiator temperature control three-way valve 4 through the radiator bypass pipeline 12. When the temperature of the lubricating oil after confluence at the radiator temperature control three-way valve 4 is higher than the target temperature, the radiator 3 fan is turned on; when the temperature of the lubricating oil after confluence at the radiator temperature control three-way valve 4 is lower than the target temperature, the radiator 3 fan is braked, and the speed of the radiator 3 fan is determined according to the temperature of the lubricating oil after confluence. The higher the oil temperature deviates from the target temperature, the higher the speed of the radiator 3 fan is, and vice versa, the lower the speed of the radiator 3 fan is until it stops.

[0043] The target temperature after confluence through the radiator 3 is adjusted to adjust the flow ratio through the radiator 3 and the bypass line to balance the overall oil supply temperature of the system. When the oil temperature after confluence is high, all the lubricating oil passes through the radiator 3. When the oil temperature after confluence is low, all the lubricating oil passes through the radiator bypass line 12, which can reduce the flow resistance of the system and the pressure of the system oil supply is relatively low.

[0044] like Figure 1As shown, in step S5, the temperature of the stator 7 is detected by the stator winding temperature sensor 8. When the temperature of the stator 7 is too high, the speed of the oil pump 2 is increased and the process returns to step S3; when the temperature of the stator 7 is within the normal range, the oil pump 2 rotates at a predetermined speed. The temperature of the stator 7 is detected by the stator winding temperature sensor 8. When the temperature of the stator 7 is lower than the set value of the stator temperature control three-way valve 5, the lubricating oil directly reaches the filter 6 through the stator bypass pipeline 13, and reaches the bearing 10 through the filter 6. The bearing 10 oil inlet temperature sensor 9 is provided on the oil inlet of the bearing 10. The bearing 10 temperature is detected by the bearing oil inlet temperature sensor 9. When the temperature of the bearing 10 is too high, the speed of the oil pump 2 is increased and the process returns to step S3; when the temperature of the bearing 10 is within the normal range, the oil pump 2 rotates at a predetermined speed. The flow rate through the stator winding is determined by the stator 7. When the stator 7 winding temperature sensor 8 detects that the temperature of the stator 7 is high, the oil pump 2 controls the flow rate of the lubricating oil through the stator 7 to be large; when the stator winding temperature sensor 8 detects that the temperature of the stator is low, the oil pump 2 controls the flow rate of the lubricating oil through the stator 7 to be small, and the overall flow resistance of the system is low.

[0045] like Figure 2 As shown, in this embodiment, taking the motor supported by the sliding bearing 10 as an example, the oil pump 2 draws lubricating oil from the oil tank 1, passes through the radiator bypass pipe 12 or the radiator 3 cooled by the electric fan, and then converges at the radiator temperature control three-way valve 4, and then passes through the generator stator 7 or the stator bypass pipe 13. The lubricating oil converges at the stator temperature control three-way valve 5, and the converging lubricating oil passes through the filter 5 to remove impurities in the lubricating oil, and then supplies oil to the bearing 10. The lubricating oil after cooling the bearing 10 returns to the oil tank 1 through gravity or an oil return pump. The speed of the radiator 3 fan and the oil pump 2 are adjustable, the radiator temperature control three-way valve 4 controls the target temperature to be the temperature of the lubricating oil after converging, and the stator temperature control three-way valve 5 controls the target temperature to be the temperature of the stator 7 winding.

[0046] The speed of the oil pump 2 can be adjusted in real time according to the loss, so that the speed of the oil pump 2 matches the target speed or stator loss, reducing the power consumption of the oil pump 2 during the entire working cycle. The two-way temperature control three-way valve and the two-level coordination of the radiator 3 fan speed can keep the oil inlet temperature stable.

[0047] Example 2

[0048] like Figure 1 and Figure 2 As shown, a control method for an oil-cooled motor system comprises the following steps:

[0049] S1, input the target speed, torque and parameters of the main motor 11;

[0050] S2, estimating the main motor bearing loss, main motor iron loss, main motor copper loss and wind wear according to the data input in step S1, and then summing the main motor bearing loss, main motor iron loss, main motor copper loss and wind wear;

[0051] S3, calculating the amount of oil required by the oil-cooled motor system, calculating the speed of the oil pump 2 according to the amount of oil, and judging whether the speed of the oil pump 2 is higher than the maximum allowable speed. When the speed of the oil pump 2 is lower than the maximum allowable speed, the main motor 11 runs at a given speed; when the speed of the oil pump 2 is higher than the maximum allowable speed, the main motor 11 runs at the maximum speed;

[0052] S4, a temperature sensor 14 is provided on the radiator bypass pipe 12, and the temperature sensor 14 detects the temperature of the lubricating oil after confluence with the radiator temperature control three-way valve 4. When the oil temperature reaches the set value of the radiator temperature control three-way valve 4, the radiator temperature control three-way valve 4 is opened, and part or all of the lubricating oil passes through the radiator 3;

[0053] S5, the stator 7 winding is connected to the stator winding temperature sensor 8, and the stator winding temperature sensor 8 is connected to the stator temperature control three-way valve 5. When the temperature of the stator 7 reaches the set value of the stator temperature control three-way valve 5, the stator temperature control three-way valve 5 is opened, and part or all of the lubricating oil passes through the stator 7;

[0054] S6, the lubricating oil in the stator 7 is converged at the stator temperature control three-way valve 5 through the pipeline, and the converged lubricating oil passes through the filter 6 to remove impurities in the lubricating oil and then supplies oil to the bearing 10. The lubricating oil after cooling the bearing 10 returns to the oil tank 1.

[0055] like Figure 3 As shown, in this embodiment, the system controls the oil pump speed by cooperating with the radiator temperature control three-way valve 4 and the stator temperature control three-way valve 5 to achieve pipeline pressure reduction when the system is running at low temperature, and takes away the heat generated by the stator 7 and the bearing 10 through the air-cooled radiator 3, wherein the fan action logic of the air-cooled radiator 3 is as follows: that is, by monitoring the oil temperature T after mixing through the radiator temperature control three-way valve 4 s This temperature has met the requirements for fan operation. The preset target oil temperature T1 is generally 45-55°C. The fan can stably control the lowest speed N1 and the highest speed N e , allowable fluctuation temperature T b , calculate the target speed N s Because the heat dissipation power of radiator 3 is designed to be greater than the heating power of the system, the oil inlet temperature of radiator 3 is generally higher than T1 (45-55°C) and is also significantly higher than the atmospheric environment temperature. Radiator 3 has a high efficiency and can achieve a balance between heating and heat dissipation power when the fan speed is low.

[0056] Specific implementation methods are as follows Figure 3As shown, given the values ​​of various parameters, calculate the speed of the radiator 3 fan Determine the minimum speed N based on the calculation result of the fan speed s Is it lower than the controllable minimum speed N1? s If the fan speed is lower than the controllable minimum speed N1, the radiator 3 fan rotates at the minimum speed N1; when the fan speed N s When the fan speed is higher than the controllable minimum speed N1, the fan speed N s With rated maximum speed N e Compare, if the fan speed N s Higher than the rated maximum speed N e , then the heat exchanger fan is N e Rotate; if the fan speed N s Lower than the rated maximum speed N e , then the heat exchanger fan is N s Rotate.

[0057] Example 3

[0058] like Figure 4 As shown, a control method for an oil-cooled motor system is different from that in Example 1. In this embodiment, the positions of the radiator temperature control three-way valve 4 and the stator temperature control three-way valve 5 can be interchanged, and the precondition for replacement is: if the power loss of the bearing 10 of the stator 7 is significantly higher than the power loss of the stator 7 under rated power and speed, and the temperature rise of the lubricating oil after passing through the bearing 10 is more significant, then the lubricating oil first passes through the radiator 3, and this scheme is consistent with the scheme in Example 1. If under rated conditions, the power loss of the stator 7 is significantly higher than the loss of the bearing 10, and the heating effect of the bearing 10 on the lubricating oil is not obvious, and the oil coming out of the oil tank 1 can directly cool the stator 7, then the positions of the two temperature control three-way valves can be replaced to better control the temperature of the system and ensure the stability of the system lubricating oil.

[0059] Example 4

[0060] like Figure 1 and Figure 2 As shown, a control method for an oil-cooled motor system comprises the following steps:

[0061] S1, input the target speed, torque and parameters of the main motor 11;

[0062] S2, estimating the main motor bearing loss, main motor iron loss, main motor copper loss and wind wear according to the data input in step S1, and then summing the main motor bearing loss, main motor iron loss, main motor copper loss and wind wear;

[0063] like Figure 1As shown, the total loss of the motor includes the main motor iron loss, main motor copper loss, bearing loss and wind wear. Using the known conditions: the voltage U, current I, speed f, lubricating oil temperature T given by the motor controller communication lub , viscosity μ0 (T0 temperature) and viscosity-temperature index β given by the lubricant manufacturer.

[0064] P all =P fe +P cu +P b +P wind

[0065] In the above formula, P all is the total loss, P fe is the main motor iron loss, P cu is the main motor copper loss, P b is the bearing loss, P wind For wind wear.

[0066] Among them, the core loss P fe :The magnetic flux density B is proportional to the input voltage U. For a certain motor, its iron loss is approximately proportional to the square of the voltage. At any speed, the motor iron loss has the following relationship with the magnetic flux density and speed:

[0067] P fe ≈K1*(Bf) 2

[0068] In the above formula, the motor generally works in the range before the magnetic flux saturation of the silicon steel sheet. At this time, the magnetic flux density B is proportional to the terminal voltage U. K1 is the shape factor, which is determined when the motor leaves the factory and can be calculated when the motor is designed. It is related to the core thickness and the properties of the silicon steel sheet itself. Therefore,

[0069] P fe =K2*(Uf) 2

[0070] In the above formula, K2=K1*K3 2 , K3 is the proportionality coefficient, that is

[0071] Among them, copper loss P cu The calculation expression is:

[0072] P=3*I 2 *R

[0073] cu

[0074] In the above formula, I is the stator phase current and R is the stator phase resistance.

[0075] For sliding bearings, the bearing loss P is proportional to the square of the bearing speed f and the grease viscosity μ.b The calculation expression is:

[0076] P b =K b *μ*f 2

[0077] In the above formula, K b is the bearing loss calculation coefficient, which is related to the bearing shape and is determined at the factory. μ is the lubricating oil viscosity, which is related to the temperature index.

[0078]

[0079] Among them, rotor wind wear P wind It is proportional to the cube of the speed f, and the expression is:

[0080] P wind =K w *f 3

[0081] In the above formula, K w It is the wind wear coefficient, which is related to air viscosity and rotor diameter and can be considered as a constant.

[0082] By using the method of factory test and actual load correction, the motor no-load loss is compared with the load loss. The iron loss, bearing loss, and wind wear are basically unchanged, but the copper loss increases. The motor no-load loss can be measured by the factory test, and the relationship curve between the no-load loss and the speed can be obtained. For any speed, the no-load loss P1 at the factory, the resistance R1 of the motor stator at the factory, and the temperature T1 of the stator during the factory test are known. To estimate the stator temperature T2 at the time, the stator current I2, for the copper wire motor

[0083] P all =P1+I2(R1*(1+0.0039*(T2-T1)))

[0084] For aluminum wire motors

[0085] P all =P1+I2(R1*(1+0.0049*(T2-T1)))

[0086] Obviously, the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A control method for an oil-cooled motor system, characterized in that: The following steps are involved: S1, input the target speed, torque and parameters of the main motor; S2, estimating the main motor bearing loss, main motor iron loss, main motor copper loss and wind wear according to the data input in step S1, and then summing the main motor bearing loss, main motor iron loss, main motor copper loss and wind wear; S3, calculating the amount of oil required by the oil-cooled motor system, calculating the oil pump speed according to the oil amount, and judging whether the oil pump speed is higher than the maximum allowable speed. When the oil pump speed is lower than the maximum allowable speed, the motor runs at a given speed; when the oil pump speed is higher than the maximum allowable speed, the motor runs at the maximum speed; S4. A temperature sensor is provided on the radiator bypass pipeline, and the temperature sensor detects the temperature of the lubricating oil after the radiator temperature control three-way valve converges. When the oil temperature reaches the set value of the radiator temperature control three-way valve, the radiator temperature control three-way valve opens, and part or all of the lubricating oil passes through the radiator; S5, the stator winding is connected to the stator winding temperature sensor, and the stator winding temperature sensor is connected to the stator temperature control three-way valve. When the stator temperature reaches the set value of the stator temperature control three-way valve, the stator temperature control three-way valve is opened, and part or all of the lubricating oil passes through the stator; S6. The lubricating oil in the stator is converged at the stator temperature control three-way valve through a pipeline. The converged lubricating oil passes through a filter to remove impurities in the lubricating oil and then supplies oil to the motor bearings. The lubricating oil after cooling the bearings returns to the oil tank.

2. The control method of an oil-cooled motor system according to claim 1, characterized in that: The temperature control target of the radiator temperature control three-way valve is the temperature of the lubricating oil after confluence, and the temperature control target of the stator temperature control three-way valve is the temperature of the stator winding.

3. The control method of an oil-cooled motor system according to claim 1, characterized in that: In the step S4, when the oil temperature of the lubricating oil is lower than the set value of the radiator temperature control three-way valve, the lubricating oil reaches the radiator temperature control three-way valve through the radiator bypass oil pipe.

4. The control method of an oil-cooled motor system according to claim 1, characterized in that: In step S4, if the oil temperature of the lubricating oil after the radiator temperature control three-way valve converges is higher than the target temperature, the radiator fan is turned on; if the oil temperature of the lubricating oil after the radiator temperature control three-way valve converges is lower than the target temperature, the radiator fan is braked.

5. The control method of an oil-cooled motor system according to claim 4, characterized in that: The target temperature after confluence at the radiator adjusts the flow ratio through the radiator and the bypass pipe to balance the overall oil supply temperature of the system. When the oil temperature after confluence is high, all the lubricating oil passes through the radiator. When the oil temperature after confluence is low, all the lubricating oil passes through the radiator bypass pipe.

6. The control method of an oil-cooled motor system according to claim 5, characterized in that: The speed of the radiator fan is determined according to the temperature of the lubricating oil after confluence. When the oil temperature deviates from the target temperature, the speed of the radiator fan is higher. Conversely, the speed of the radiator fan is lower until it stops.

7. The control method of an oil-cooled motor system according to claim 1, characterized in that: In step S5, the stator temperature is detected by the stator winding temperature sensor. When the stator temperature is too high, the oil pump speed is increased and the process returns to step S3. When the stator temperature is within a normal range, the oil pump keeps rotating at a predetermined speed.

8. The control method of an oil-cooled motor system according to claim 1, characterized in that: In step S5, the stator temperature is detected by the stator winding temperature sensor. When the stator temperature is lower than the set value of the stator temperature control three-way valve, the lubricating oil directly reaches the filter through the stator bypass pipeline and reaches the bearing through the filter.

9. The control method of an oil-cooled motor system according to claim 8, characterized in that: A bearing oil inlet temperature sensor is provided on the bearing oil inlet line, and the bearing temperature is detected by the bearing oil inlet temperature sensor. When the bearing temperature is too high, the oil pump speed is increased and returns to step S3; when the bearing temperature is within the normal range, the oil pump maintains the predetermined speed.

10. The control method of an oil-cooled motor system according to claim 8, characterized in that: The flow rate through the stator winding is determined by the stator. When the stator winding temperature sensor detects that the stator temperature is high, the oil pump controls the flow rate of the lubricating oil through the stator to be large; when the stator winding temperature sensor detects that the stator temperature is low, the oil pump controls the flow rate of the lubricating oil through the stator to be small.

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