Disclosure of Invention
The invention provides a traction converter cooling system based on boiling heat transfer, which can realize heat dissipation of high-power and high-heat-flux power electronic devices.
The invention adopts the following technical means:
The traction converter cooling system based on boiling heat transfer comprises a pump, a cold plate, a filter, a main loop flow regulating device, a surge tank, a condenser flow regulating device, a condenser outlet pipeline, a bypass pipeline, a branch loop flow regulating device and a monitoring system, wherein the cold plate is communicated with an outlet of the pump through a cold plate inlet main pipeline;
The monitoring system comprises a monitoring unit and a control unit;
The monitoring unit comprises a first temperature monitoring device and a first pressure monitoring device which are arranged on the cold plate inlet main pipeline;
The monitoring unit is used for collecting a temperature signal T1 and a pressure signal P1 of the main pipeline of the cold plate inlet and transmitting the temperature signal T1 and the pressure signal P1 to the control unit;
The control unit is configured to receive the pressure signal P1, calculate a boiling point Tf of the working medium under the pressure according to the pressure signal P1, calculate a precooling margin Δt=tf-T1, and determine whether the precooling margin Δt is within a set value range, if not, the control unit adjusts at least one of an opening of the main circuit flow regulator, an opening of the condenser flow regulator, an opening of the sub-circuit flow regulator, and a rotational speed of a fan of the condenser, so that the precooling margin Δt is within the set value range, and if yes, perform the next acquisition.
Further, the main loop flow regulating device is a three-way regulating valve, an inlet of the three-way regulating valve is communicated with an outlet of the pump through a pipeline, a first outlet of the three-way regulating valve is communicated with the filter, and a bypass pipeline is communicated with a second outlet of the three-way regulating valve and the inlet of the pump.
Further, the main loop flow regulating device is a two-way regulating valve, the bypass pipeline is communicated with the outlet of the pump and the inlet of the pump, and the two-way regulating valve is arranged on the bypass pipeline.
Further, one end of the cold plate outlet main pipeline connected with the surge tank is arranged at the middle lower part of the surge tank, one end of the condenser inlet pipeline connected with the surge tank is arranged at the middle upper part of the surge tank, and one end of the return pipeline connected with the surge tank is arranged at the bottom of the surge tank.
Further, the cold plate is provided with a plurality of groups, the inlets of the cold plates are respectively communicated with the main pipeline of the inlet of the cold plate through branch pipelines of the inlet of the cold plate, and the outlets of the cold plates are respectively communicated with the main pipeline of the outlet of the cold plate through branch pipelines of the outlet of the cold plate.
Further, the surge tank is further provided with a safety valve, the monitoring unit further comprises a third pressure monitoring device arranged on the surge tank, the third pressure monitoring device collects pressure signals Px on the surge tank and transmits the pressure signals Px to the control unit, and the control unit judges whether the received pressure signals Px are larger than a preset pressure limit value or not, if yes, the control unit controls the safety valve to be opened.
Further, a third temperature monitoring device for collecting a pump inlet temperature signal T3 is further arranged on the outlet pipeline of the condenser.
Further, a second pressure monitoring device for collecting the pressure signal P2 on the cold plate outlet main pipeline and a second temperature monitoring device for collecting the temperature signal T2 on the cold plate outlet main pipeline are further arranged on the cold plate outlet main pipeline.
Further, the condenser is any one of a plate fin radiator, a tube strip radiator and a tube fin radiator.
Compared with the prior art, the traction converter cooling system based on boiling heat transfer has the advantages that the boiling cooling system based on two-phase boiling heat transfer is adopted to replace the existing liquid cooling system based on single-phase convection heat transfer, and the latent heat of vaporization (latent heat) of working media is tens times or even tens times of specific heat (sensible heat), so that the heat taken away during evaporation is a plurality of times or even tens of times of heat taken away by convection heat transfer. Therefore, the evaporating end of the cooling system, namely the cold plate, has stronger heat absorbing capacity. When the heat flux density of the power electronic device exceeds 20-30W/cm2, the traditional single-phase liquid cooling system cannot meet the heat dissipation requirement because the volume and the weight of the traction converter cooling system are limited, and the traction converter cooling system provided by the scheme can provide an efficient cooling system for a high-power and high-heat flux density traction converter.
The boiling cooling system based on two-phase boiling heat transfer is adopted to replace the existing liquid cooling system based on single-phase convection heat transfer, and the superheat degree in the working medium evaporation process only needs to be 3-5 ℃ higher than the boiling point temperature under the saturation pressure, so that the corresponding working medium boiling point is higher (up to 75 ℃) when the temperature of the plate surface of the cold plate is not higher than 80 ℃, and the temperature of liquid at the outlet of the cold plate is higher than that of the cooling plate of the single-phase cooling system based on convection heat transfer (usually 60-64 ℃), namely the temperature of the working medium reaching the inside of the condenser is higher, and the heat release capacity of the condenser is stronger under the condition that the temperature and the flow of cooling air are the same. Therefore, on the premise of the same heat dissipation capacity requirement, the volume of the cooling device at the condensing end of the cooling system can be reduced, the weight of the cooling device is reduced, and the structural compactness is improved.
In addition, as the boiling point of the corresponding working medium is higher than the temperature of the liquid at the outlet of the cooling plate of the cooling system based on single-phase convection heat exchange when the temperature of the plate surface of the cooling plate is not higher than 80 ℃, that is to say, the temperature of the working medium reaching the inside of the condenser is higher, and the air quantity of the required fan is smaller under the conditions of the same heat dissipation requirement and the same cooling air inlet temperature. On the premise of the same heat dissipation capacity requirement, the ventilation quantity of the fan of the cooling system can be reduced, the noise is reduced, and the power consumption of a motor driving the fan is reduced. Therefore, the cooling system of the scheme has lower energy consumption, is more energy-saving and has better environmental friendliness.
Detailed Description
As shown in fig. 1, the traction converter cooling system based on boiling heat transfer disclosed by the invention comprises a pump 1, a cold plate 8 communicated with an outlet of the pump 1 through a cold plate inlet main pipeline 5, a filter 4 arranged on the cold plate inlet main pipeline 5, a main loop flow regulating device 2 arranged between the pump 1 and the filter 4, a surge tank 11 communicated with an outlet of the cold plate 8 through a cold plate outlet main pipeline 10, a condenser 14 communicated with the surge tank 11 through a condenser inlet pipeline 13, a condenser flow regulating device 12 arranged on the condenser inlet pipeline 13, a condenser outlet pipeline 16 communicated with an outlet of the condenser 14 and an inlet of the pump 1, a bypass pipeline 19 communicated with an outlet and an inlet of the pump 1, a return loop flow regulating device 18 arranged on the return loop pipeline 17 and a monitoring system, wherein the return loop flow regulating device is arranged on the return loop 17;
As shown in fig. 1, the pump 1, the filter 4, the cold plate 8, the surge tank 11, the condenser 14, the flow adjusting devices and the pipelines form a working medium loop system, the working medium loop system is filled with working medium, and the boiling point of the working medium is as follows: the working medium loop system is sealed after working medium is filled at normal pressure not higher than 80 ℃, the internal pressure is lower than 1 standard atmospheric pressure, the power electronic components 7 are arranged on the cold plates, preferably, the cold plates are arranged in parallel in multiple groups, the number of the cold plates in the drawing is two groups, the inlets of the multiple groups of the cold plates 8 are respectively communicated with the cold plate inlet main pipeline 5 through the cold plate inlet branch pipelines 6, the outlets of the multiple groups of the cold plates 8 are respectively communicated with the cold plate outlet main pipeline 10 through the cold plate outlet branch pipelines 9, a fourth temperature monitoring device 26 is arranged on the surface of the cold plates, the fourth temperature monitoring device is arranged on a typical position point which is a certain distance from the power electronic components on the surface of the cold plates, the fourth temperature monitoring device can be arranged on each cold plate of the multiple groups of the cold plates which are arranged in parallel, can also be arranged on the typical cold plates through test verification, the fourth temperature monitoring device is used for monitoring the temperatures Tb1, tb1 and … … Tbn of the cold plate surfaces, and the obtained cold plate surface temperature signals are transmitted to the control unit, and the condenser is any one of a plate fin type radiator, a strip radiator and a tube type radiator. The working medium circularly flows in the working medium loop system under the action of the pump, when the power electronic components work, heat is generated due to heat loss, the heat is conducted to the inner wall of the working medium through the outer wall of the cold plate, the working medium flowing through the inner cavity of the cold plate is heated to boil, the working medium is changed into steam from liquid, a large amount of heat is absorbed in the process, the working medium which becomes gas phase after evaporation and a small part of liquid phase working medium which is not evaporated form a mixed phase working medium, the mixed phase working medium flowing out of the outlet pipeline of the cold plate is converged in the main pipeline of the outlet of the cold plate and flows to the pressure stabilizing box, the gas-liquid mixed phase working medium flows into the condenser after flowing through the pressure stabilizing box and then enters the condenser through the flow regulating device of the condenser, the steam heat in the condenser is taken away by cooling air, the steam is liquefied, and the liquefied working medium flows to the inlet of the pump along the outlet pipeline of the condenser.
When the main circuit flow regulating device 2 is a three-way regulating valve, an inlet of the three-way regulating valve is communicated with an outlet of the pump 1 through a pipeline, a first outlet of the three-way regulating valve is communicated with the filter 4, and a bypass pipeline 19 is communicated with a second outlet of the three-way regulating valve and an inlet (condenser outlet pipeline) of the pump 1. When the main circuit flow regulator 2 is a two-way regulator, the bypass line 19 communicates the outlet of the pump 1 with the inlet of the pump 1 (condenser outlet line), and the two-way regulator is provided on the bypass line 19. Through the bypass pipeline 19 and the main loop flow regulating device 2, the flow of working medium flowing through the cold plate can be regulated, and the working medium in the cold plate can be ensured to work effectively.
The sub-circuit line 17 communicates the surge tank 11 with an inlet (condenser outlet line) of the pump 1, and the sub-circuit flow rate adjustment device 18 is provided on the sub-circuit line 17. Through setting up branch loop system to temperature data and pressure data through temperature monitoring devices and pressure monitoring devices collection can real-time regulation through cold plate and condenser's working medium flow, in order to guarantee that the working medium through cold plate can get into saturated nucleate boiling fast, guarantee the heat dispersion of cold plate.
The condenser inlet pipeline 13 is provided with a condenser flow regulating device 12, so that the flow of working medium passing through the condenser can be regulated in real time, the working medium passing through the cold plate can be ensured to rapidly enter saturated nucleate boiling, and the heat dissipation capacity of the cold plate is ensured.
The monitoring system comprises a monitoring unit and a control unit 3;
the monitoring unit comprises a first temperature monitoring device 20 and a first pressure monitoring device 21 which are arranged on the main cooling plate inlet pipeline 5;
The monitoring unit is used for collecting a temperature signal T1 and a pressure signal P1 of the main pipeline of the cold plate inlet and transmitting the temperature signal T1 and the pressure signal P1 to the control unit;
The control unit 3 is configured to receive the pressure signal P1, calculate a boiling point Tf of the working medium under the pressure according to the pressure signal P1, calculate a precooling margin Δt=tf-T1, and determine whether the precooling margin Δt is within a set value range, if not, the control unit adjusts at least one of an opening of the main circuit flow regulator, an opening of the condenser flow regulator, an opening of the sub-circuit flow regulator, and a rotational speed of a fan of the condenser, so that the precooling margin Δt is within the set value range, and if yes, perform the next acquisition.
The system further comprises a second temperature monitoring device 22, a second pressure monitoring device 23, a third temperature monitoring device 24 and a third pressure monitoring device 25, wherein the second temperature monitoring device 22 and the second pressure monitoring device 23 are arranged on the cold plate outlet main pipeline 10, the third temperature monitoring device 24 is arranged on the condenser outlet pipeline 16, the third pressure monitoring device 25 is arranged on the surge tank 11, the second temperature monitoring device 22 is used for collecting the working medium temperature T2 in the cold plate outlet main pipeline, the second pressure monitoring device 23 is used for collecting the working medium pressure P2 in the cold plate outlet main pipeline, the third temperature monitoring device 24 is used for collecting the pump inlet working medium temperature T3, and the third pressure monitoring device 25 is used for collecting the working medium pressure Px in the surge tank. The temperature monitoring device and the pressure monitoring device are connected with the control unit, the control unit can be independently arranged and is called as a control box of the traction converter cooling system, the control unit can also be arranged in the traction converter control unit, the control unit collects temperature values and pressure values of all monitoring positions in the cooling system, and executing mechanisms such as a fan and a flow regulating device are controlled according to the obtained temperature values and pressure values, so that the cooling system heat dissipation capacity, namely the surface temperature control of the cooling plate is realized, and meanwhile, the system safety is ensured.
Preferably, one end of the cold plate outlet main pipeline connected with the surge tank is arranged at the middle lower part of the surge tank, one end of the condenser inlet pipeline connected with the surge tank is arranged at the middle upper part of the surge tank, and one end of the return pipeline connected with the surge tank is arranged at the bottom of the surge tank. This design ensures that the liquid working medium directly flows back to the pump 1 through the return line 17, while the gaseous working medium flows to the condenser. The liquid working medium in the main pipeline of the cold plate inlet is effectively ensured, namely the cooling heat dissipation capacity is ensured.
According to the traction converter cooling system, the pressure stabilizing box with relatively large volume is directly arranged between the cold plate outlet pipeline and the condenser inlet pipeline, the gas has relatively large compressibility, the instant pulsation of the cold plate outlet pressure is restrained, and the pressure in the cold plate outlet main pipeline is ensured to be relatively stable; by matching with the pipeline design, the mutual influence of flow and pressure among the parallel cold plates caused by different instantaneous heating powers of the power electronic components can be controlled within an allowable range. The design provides a guarantee for safe, reliable and normal operation of the cooling system. When the heat loads on the surfaces of the multiple groups of cold plates are different, the vaporization quantity of the working medium in the cold plate with large heat load is large, and the working medium in the main pipeline of the inlet of the cold plate can be timely sucked into the cold plate through the branch pipe of the inlet of the cold plate to supplement the working medium, so that the automatic distribution of the flow of the working medium in the multiple groups of cold plates is ensured, and the safe work of each cold plate under different loads is ensured.
The pressure stabilizing box is further provided with a safety valve, the monitoring unit further comprises a third pressure monitoring device 25 arranged on the pressure stabilizing box 11, the third pressure monitoring device 25 collects pressure signals Px on the pressure stabilizing box and transmits the pressure signals Px to the control unit, and when the received pressure signals Px are larger than a preset pressure limit value, the control unit controls the safety valve to be opened so as to ensure the stability of pressure in the cooling system.
The filter of the cooling system is used for ensuring the cleanness of working medium entering the cold plate, avoiding the local overheating phenomenon of the cold plate caused by the blockage of the internal channel of the cold plate by impurities and ensuring the safety of power electronic components mounted on the surface of the cold plate.
The invention discloses a traction converter cooling system based on boiling heat transfer, which comprises the following working processes:
The cooling loop system is filled with working medium, and the boiling point of the working medium is as follows: the normal pressure is not higher than 80 ℃, the cooling system is sealed after being filled with working medium, the internal pressure is lower than 1 standard atmospheric pressure, the power electronic component 7 is arranged on the cold plate, the control unit of the monitoring system is connected with each temperature monitoring device, each pressure monitoring device and each fan, and the parameter measuring points of the monitoring unit monitoring cooling system of the monitoring system are set as follows and mainly comprise:
The first temperature monitoring device is arranged on the main pipeline of the cold plate inlet and is used for measuring the temperature T1 of the working medium in the main pipeline of the cold plate inlet;
the second temperature monitoring device is arranged on the main pipeline of the cold plate outlet and is used for measuring the temperature T2 of the working medium in the main pipeline of the cold plate outlet;
The third temperature monitoring device is arranged on the main pipeline of the pump inlet and is used for measuring the temperature T3 of the working medium at the pump inlet;
a fourth temperature monitoring device arranged on the surface of the cold plate and having a typical position point with a certain distance from the power electronic components arranged on the surface of the cold plate, and used for measuring the temperatures Tb1, tb1 and … … Tbn of the surface of the cold plate;
The first pressure monitoring device is arranged on the main pipeline of the cold plate inlet and is used for measuring the pressure P1 of the working medium in the main pipeline of the cold plate inlet;
the second pressure monitoring device is arranged on the main pipeline of the cold plate outlet and is used for measuring the pressure P2 of the working medium in the main pipeline of the cold plate outlet;
And the third pressure monitoring device is arranged at the upper end of the surge tank and is used for measuring the pressure Px of the working medium in the surge tank.
The temperature monitoring device and the pressure monitoring device measure the temperature and the pressure of the monitoring point according to the set time interval and transmit data to the control unit of the monitoring system.
The traction converter cooling system based on boiling heat transfer can be controlled by controlling the temperature and the flow of a working medium to ensure the heat radiation performance of a cold plate, and specifically, the control process is as follows:
a) When the temperature Tbn of the typical position point of the cold plate measured by the monitoring device is higher than a preset early warning value Tb-1 but smaller than a preset warning value Tb-2, and the precooling margin Δt is smaller than a preset lower limit value, the control unit sends out a signal to perform one or more of the following control: (1) The opening of the main loop flow regulating device is increased according to a preset value, and the flow of the working medium at the inlet of the cold plate is increased; (2) The opening of the sub-loop flow regulating device is reduced according to a preset value, the flow of working medium flowing into the inlet of the pump and not cooled by the condenser is reduced, and the temperature T3 of the working medium at the inlet of the pump is reduced; (3) The opening of a flow regulating device of the condenser is increased according to a preset value, the flow of working medium flowing through the condenser is increased, and the temperature T3 of the working medium at the inlet of the pump is reduced, so that the temperature T1 of the working medium at the inlet of the cold plate is reduced; (4) Increasing the rotating speed of a fan at the condenser end, and reducing the temperature T3 of a working medium at the inlet of the pump; further, the temperature T1 of the working medium at the inlet of the cold plate is reduced, and the precooling margin delta T of the cold plate is improved.
When the temperature Tbn of the typical position point of the cold plate measured by the monitoring device is higher than a preset early warning value Tb-1 but smaller than a preset warning value Tb-2, and the precooling margin Δt is higher than a preset upper limit value, the control unit sends out a signal to perform one or more of the following control: (1) The opening of the main loop flow regulating device is increased according to a preset value, and the flow of the working medium at the inlet of the cold plate is increased; (2) The opening of the split-loop flow regulating device is increased according to a preset value, the flow of working medium flowing into the inlet of the pump and not cooled by the condenser is increased, and the temperature T3 of the working medium at the inlet of the pump is increased; (3) The opening of a flow regulating device of the condenser is reduced according to a preset value, the flow of working medium flowing through the condenser is reduced, the temperature T3 of the working medium at the inlet of the pump is increased, and the temperature T1 of the working medium at the inlet of the cold plate is increased; (4) The rotating speed of a fan of the condenser is reduced, and the temperature T3 of a working medium at the inlet of the pump is increased; and further increasing the temperature T1 of the working medium at the inlet of the cold plate so as to reduce the precooling margin delta T of the cold plate. In this embodiment, the pre-cooling margin Δt is set to 2-10 ℃, i.e., the lower limit of the pre-cooling margin Δt is set to 2 ℃, the upper limit is set to 10 ℃, and the specific range of the pre-cooling margin Δt can be set according to the requirements. The precooling margin delta T is maintained within a set value range, so that the heat exchange efficiency and the heat dissipation capacity of the cold plate can be ensured.
When the temperature Tbn of the typical position point of the cold plate measured by the monitoring device is higher than a preset early warning value Tb-1 but smaller than a preset warning value Tb-2 and the precooling margin Δt is within a set range, the control unit sends out a signal to control as follows: and the opening of the main loop flow regulating device is increased according to a preset value, the flow of working medium at the inlet of the cold plate is increased, and the heat dissipation capacity of the cold plate is improved.
B) When the temperature Tbn of the typical position point of the cold plate measured by the monitoring device is higher than a preset alarm value Tb-2 but smaller than a preset limit value Tb-3, the control unit sends out a signal, and the converter reduces power to operate.
C) When the temperature Tbn of the typical position point of the cold plate measured by the monitoring device is higher than a preset limit value Tb-3, the control unit sends a signal to cut off the converter so as to stop working, and the components mounted on the surface of the cold plate are protected from being damaged due to overheating.
D) The control unit calculates the boiling point Tf of the working medium under the pressure according to the pressure P1 measured by the monitoring device and the physical property parameter table of the working medium, and then calculates the precooling margin DeltaT=Tf-T1.
E) The control unit compares the pressure P2 measured by the monitoring device with a preset pressure limit value, and when the pressure P2 exceeds the preset pressure limit value, the control unit sends out an early warning signal according to preset logic or enables the converter to run with reduced power or cuts off the converter to stop working.
F) The control unit compares the pressure Px measured by the monitoring device with a preset pressure limit value, when the pressure Px exceeds the preset pressure limit value, the safety valve at the top of the pressure stabilizing box is opened, and the control unit sends out a signal to cut off the converter to stop working.
The traction converter cooling system based on boiling heat transfer disclosed by the invention realizes the pre-cooling margin delta T regulation, wherein the pre-cooling margin delta T regulation is realized by a temperature measuring device, a main loop flow regulating device, a condenser flow regulating device, a sub-loop flow regulating device and a fan rotating speed control system which are arranged on an inlet main pipeline of a cold plate, and the pre-cooling margin regulation provides effective guarantee for the heat dissipation capacity of the boiling heat transfer cooling system disclosed by the invention. The precooling margin is too large, and the working medium cannot enter saturated nucleate boiling as soon as possible after entering the cold plate, but needs to pass through a longer section of single-phase convection heat transfer process, but the single-phase convection heat transfer capacity of the working medium is much lower than that of the conventional cooling liquid, so that the advantage of boiling heat transfer cannot be exerted. The traction converter cooling system based on boiling heat transfer disclosed by the invention ensures that the difference value between the boiling point temperature of the working medium (corresponding to the boiling point under the condition of the pressure P1 on the main pipeline of the inlet of the cold plate) and the temperature T1 of the working medium in the main pipeline of the inlet of the cold plate meets the requirement of a preset value delta T, so that the temperature of the inlet of the cold plate is in a micro supercooling state. Thus, part of working medium enters the nucleate boiling state soon after entering the cold plate, and the working medium continuously nucleates boiling in the process of flowing through the cold plate. The design ensures the high-efficiency heat absorption capacity of the cold plate, ensures the uniformity of the temperature of the whole plate surface from the inlet to the outlet of the cold plate, reduces the thermal stress suffered by the power electronic components arranged on the surface of the cold plate, improves the use reliability of the power electronic components and prolongs the service life of the power electronic components.
The monitoring system of the traction converter cooling system also has the advantages that when the temperature of the typical position point of the cooling plate is higher than a preset value due to the change of the environmental temperature, the altitude and the operating condition (the heating power of the power electronic components), the cooling system can automatically adjust the heat dissipation capacity of the cooling system according to the surface temperature of the cooling plate, so that the cooling system can normally operate under the working condition of lowest noise and most energy saving, and the heat dissipation requirement is met; and meanwhile, the operation reliability of the cooling system under complex conditions and working conditions is improved. The heat-dissipating device has the advantages of high heat-transferring efficiency, strong heat-transferring capability, compact structure, low noise and power consumption, higher reliability and safety, and can well solve the main bottleneck problem of development of the high-power and high-heat-flux traction converter, namely the heat dissipation problem.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.