Design method of train traction converter cooling system

Abstract

The invention relates to the technical field of rail transit, in particular to a train traction converter cooling system design method. The method comprises the following steps: acquiring train line operation data; calculating the power device loss of the traction converter according to the train line operation data; calculating the junction temperature of the power device by combining the cooling system parameters of the traction converter and the calculation result of the power device loss of the traction converter; calculating the service life of the power device according to the junction temperature calculation result of the power device; and performing optimization design on the cooling system parameters based on the service life calculation result of the power device, and repeating the junction temperature and service life calculation of the power device until the service life calculation result of the power device meets the design service life requirement. According to the method, the service life calculation and the service life design of the traction converter power device are carried out for the actual train route, comprehensive optimization matching of the traction converter cooling system is achieved, and therefore the purpose of improving the overall system performance and reliability is achieved.

Description

Technical Field

[0001] The present invention relates to the field of rail transit technology, and more specifically, to a design method for a cooling system of a train traction converter. Background Art

[0002] The main power device of the traction converter is IGBT (insulated gate bipolar transistor). IGBT is a high-frequency on-off power device that consumes electrical energy when working and converts electrical energy into heat energy. Usually, the current flowing through the IGBT is large, and the on-off frequency of the IGBT is also high, so the device generates a large amount of heat. If the generated heat cannot be dissipated effectively and in a timely manner, the junction temperature inside the IGBT module will exceed the allowable value and the IGBT may be damaged. Relevant data show that for every 2°C increase in the temperature of electronic components, the reliability decreases by 10%, and the lifespan at a temperature rise of 50°C is only 1 / 6 of that at a temperature rise of 25°C. Therefore, only by quickly and promptly dissipating the generated heat can the normal operation of the IGBT be guaranteed.

[0003] The cooling system design of the traction converter has always been one of the cores of the traction converter design. The cooling methods of the traction converter mainly include running air cooling, forced air cooling, forced air cooling + water cooling, etc. How to optimize the design of the cooling system has always been one of the most critical issues. The heat dissipation capacity of the traction converter cooling system directly affects the converter performance and the safe and stable operation of the traction system. Ensuring that the maximum temperature rise of the IGBT is within the allowable value range and that the life of the IGBT meets the service life of the train running on the scheduled route is one of the most important tasks in the design of the traction converter cooling system.

[0004] The current air cooling system of the traction inverter mainly adopts various cooling methods such as water cooling, air cooling or running air cooling. The main factors considered in its design and implementation include key indicators such as the constancy of the heat dissipation power, whether the heat dissipation power is adjustable, reducing the noise level and the service life of the cooling system.

[0005] For example, the cooling system of a CRH380BL traction converter proposed in Chinese invention patent CN 102916567 A is a water cooling system, which mainly discloses a constant power control cooling system. Another Chinese invention patent CN104901557A proposes an intelligent converter cooling system and intelligent cooling control method, which further adds the regulation and control of the water cooling medium and the fan flow on the basis of the aforementioned patent to achieve the purpose of regulating the cooling effect. The controlled variable is to maintain the temperature rise of the power device below the safe allowable value.

[0006] In the existing train traction converter design, the cooling system usually has two working modes: one is to work continuously according to the rated cooling power, and the other is to adjust the cooling power according to the temperature rise of the power device. However, these designs often ignore the design of the cooling system based on the life of the IGBT in the traction converter, and fail to fully consider the impact of the cooling system on the life of the IGBT. Summary of the invention

[0007] The purpose of the present invention is to provide a method for designing a cooling system for a train traction converter, so as to solve the problem that the design of the cooling system for a train traction converter in the prior art does not fully consider the impact on the life of an IGBT module.

[0008] In order to achieve the above object, the present invention provides a method for designing a cooling system for a train traction converter, comprising the following steps:

[0009] Obtain train line operation data;

[0010] Calculate the power device losses of the traction converter based on the train line operation data;

[0011] Calculate the junction temperature of the power device by combining the cooling system parameters of the traction converter with the calculation results of the power device loss of the traction converter;

[0012] Calculate the life of the power device based on the junction temperature calculation results of the power device;

[0013] The cooling system parameters are optimized based on the life calculation results of the power device, and the junction temperature and life calculation of the power device are repeated until the life calculation results of the power device meet the design life requirements.

[0014] In some embodiments, the train line operation data is the train full line operation data;

[0015] The train line operation data includes the current and voltage on the input side of the converter, the current and voltage on the output side, and the train running time and speed.

[0016] In some embodiments, the traction converter cooling system parameters are related to the cooling method adopted, and the cooling method includes water cooling, air cooling, running air cooling, heat pipe cooling and forced air cooling.

[0017] In some embodiments, the cooling method is water cooling, and the traction inverter cooling system parameters include radiator parameters, pump parameters, fan parameters, heat exchanger parameters and cooling system pipeline resistance.

[0018] In some embodiments, the traction inverter cooling system includes a water cooling plate, and the traction inverter cooling system parameters include cooling liquid flow rate, cooling liquid inlet temperature, heat dissipation power of heat-generating devices installed on the water cooling plate, the maximum allowable temperature of the water cooling plate surface, and the maximum allowable thermal resistance of the water cooling plate.

[0019] In some embodiments, the power device is an IGBT module including a plurality of IGBT chips and a FWD chip.

[0020] In some embodiments, the IGBT module loss includes the IGBT chip loss P T and FWD chip loss P D .

[0021] In some embodiments, the IGBT chip loss P T Including IGBT steady-state loss P sat and IGBT switching loss P on+off ;

[0022] IGBT steady-state loss P sat , the corresponding expression is as follows:

[0023]

[0024] IGBT switching loss P on+off , the corresponding expression is as follows:

[0025]

[0026] Where D is the duty cycle, MR is the modulation depth, and θ is the initial phase angle;

[0027] V CE(sat) is the collector (C)-emitter (E) saturation voltage;

[0028] I CP For the current passing through the IGBT chip, the current sensor tests the current peak value of the effective value;

[0029] x is the phase angle;

[0030] P sw(on) is the turn-on loss of the IGBT chip;

[0031] P sw(off) is the turn-off loss of the IGBT chip;

[0032] f c is the switching frequency of the IGBT module.

[0033] In some embodiments, the FWD chip loss P D Including FWD steady-state loss P Fand FWD reverse recovery loss P rr ;

[0034] FWD steady-state loss P F , the corresponding expression is as follows:

[0035]

[0036] FWD reverse recovery loss P rr , the corresponding expression is as follows:

[0037]

[0038] Where MR is the modulation depth, θ is the initial phase angle, V CC is the intermediate voltage;

[0039] x is the phase angle;

[0040] I CP is the current passing through the IGBT chip, and is the current peak value of the effective value of the current extracted during train operation;

[0041] I rr is the reverse recovery current, which is the operating parameter of the FWD chip;

[0042] t rr is the reverse recovery time, which is the action parameter of the FWD chip;

[0043] f c is the switching frequency of the IGBT module;

[0044] V EC is the forward voltage of the diode and is the operating parameter of the FWD chip.

[0045] In some embodiments, the step of calculating the junction temperature of the power device by combining the traction converter cooling system parameters with the calculation results of the power device loss of the traction converter further comprises:

[0046] Get the IGBT module case temperature Tc;

[0047] IGBT chip junction temperature T based on traction converter cooling system parameters j(T) Calculation, and

[0048] Based on the parameters of the traction converter cooling system, the FWD chip junction temperature T j(D) calculate.

[0049] In some embodiments, the calculation formula of the IGBT module case temperature Tc is as follows:

[0050] T C =(P T +P D)×R th(c-f)T热耦合 +(P T +P D )×R th(f-a) +Ta;

[0051] Among them, R th(c-f)T热耦合 It is the equivalent thermal resistance of the thermal grease between the IGBT module base plate and the heat sink after considering the thermal coupling effect;

[0052] R th(f-a) is the thermal resistance of the heat sink itself;

[0053] Ta is the temperature of the heat sink below the IGBT module;

[0054] P T is the IGBT chip loss;

[0055] P D FWD chip loss.

[0056] In some embodiments, the junction temperature T j(T) and FWD chip junction temperature T j(D) The calculation formulas are as follows:

[0057] T j(T) =P T ×R th(j-c)T +T C =P T ×R th(j-c)T +(P T +P D )×R th(c-f)T热耦合 +(P T +P D )×R th(f-a) +Ta;

[0058] T j(D) =P D ×R th(j-c)D +T C =P D ×R th(j-c)D +(P T +P D )×R th(c-f)T热耦合 +(P T +P D )×R th(f-a) +Ta;

[0059] Among them, R th(j-c)D is the thermal resistance between the junction temperature and the case temperature of the FWD chip;

[0060] R th(j-c)T It is the thermal resistance between the junction temperature and the case temperature of the IGBT chip;

[0061] R th(c-f)T热耦合 It is the equivalent thermal resistance of the thermal grease between the IGBT module base plate and the heat sink after considering the thermal coupling effect;

[0062] R th(f-a) is the thermal resistance of the heat sink itself;

[0063] Ta is the temperature of the heat sink below the IGBT module;

[0064] Tc is the case temperature below the IGBT module;

[0065] P T is the IGBT chip loss;

[0066] P D FWD chip loss.

[0067] In some embodiments, the equivalent thermal resistance R of the thermal conductive silicone grease between the IGBT module base plate and the heat sink after considering the thermal coupling effect is th(c-f)T热耦合 , the corresponding expression is:

[0068]

[0069] Among them, R th(c-f)T测试值 It is the test value when the IGBT chip or FWD chip is working; k1 is the chip coupling coefficient; k2 is the substrate coupling coefficient; S is the chip distance, and D is the substrate thickness.

[0070] In some embodiments, the calculating the life of the power device according to the junction temperature calculation result of the power device further includes:

[0071] The temperature variation operating matrix junction temperature of the IGBT module is calculated, and the life of the IGBT module is calculated based on the matrix data.

[0072] In some embodiments, the calculation to obtain the temperature variation operation matrix junction temperature of the IGBT module and the IGBT module life calculation based on the matrix data further include:

[0073] Calculate the case temperature change ΔT of the IGBT module c Operation matrix, IGBT operation junction temperature change ΔT jT Operation matrix and FWD operation junction temperature change ΔT jD The operation matrix of

[0074] According to the actual operation process ΔT c , ΔT jT , ΔT jDThe relationship between the amplitude of temperature change and the corresponding number of cycles is obtained by obtaining the corresponding cycle life value in the cycle life curve corresponding to the IGBT module, thereby calculating the life of the IGBT module.

[0075] In some embodiments, the IGBT module ΔT c The cumulative lifespan calculation formula is as follows:

[0076]

[0077] IGBT module ΔT jT The cumulative lifespan calculation formula is as follows:

[0078]

[0079] IGBT module ΔT jD The cumulative lifespan calculation formula is as follows:

[0080]

[0081] in, Refers to the cumulative life of the IGBT module under the condition of cyclic changes in the junction temperature of the IGBT chip;

[0082] Refers to the cumulative life of the IGBT module under the condition of cyclic changes in the junction temperature of the FWD chip;

[0083] L (ΔTc) It refers to the IGBT module at the shell temperature T c Cumulative life under cyclic variation conditions;

[0084] n jTi It means that under different IGBT chip junction temperature change cycles, the IGBT module is under a certain temperature difference ΔT jTi The number of cycles in the case;

[0085] n jDi It means that under different FWD chip junction temperature change cycles, the IGBT module is under a certain temperature difference ΔT jDi The number of cycles in the case;

[0086] n ci It means that under different shell temperature change cycles, the IGBT module is under a certain temperature difference ΔT ci The number of cycles in the case;

[0087] N jTi Indicates the corresponding temperature difference ΔT jTi Under this condition, the rated life or maximum permissible number of cycles of the IGBT module;

[0088] N jDiIndicates the corresponding temperature difference ΔT jDi Under this condition, the rated life or maximum permissible number of cycles of the IGBT module;

[0089] N ci Indicates the corresponding temperature difference ΔT ci The rated life or maximum allowable number of cycles of the IGBT module.

[0090] The present invention proposes a train traction inverter cooling system design method based on the actual operating conditions of the train. The life calculation and life design of the traction inverter power devices are performed based on the actual line route operating conditions of the train, and the cooling system parameters of the traction inverter are optimized and designed. The cooling system parameters and IGBT life and other factors are comprehensively considered to achieve comprehensive optimization and matching of the traction inverter cooling system, thereby ensuring the safe and stable operation of the equipment while extending the service life of key components such as IGBT, ultimately achieving the purpose of improving the overall system performance and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which the same reference numerals always represent the same features, wherein:

[0092] Figure 1 A step diagram of a method for designing a cooling system for a train traction converter according to an embodiment of the present invention is disclosed;

[0093] Figure 2 A flow chart of a method for designing a cooling system for a train traction converter according to an embodiment of the present invention is disclosed;

[0094] Figure 3 A schematic diagram of train operation data according to an embodiment of the present invention is disclosed;

[0095] Figure 4 Disclosed is a loss composition diagram of an IGBT module according to an embodiment of the present invention;

[0096] Figure 5 A thermal equivalent model diagram of an IGBT module according to an embodiment of the present invention is disclosed;

[0097] Figure 6 A schematic diagram of heat sink temperature according to an embodiment of the present invention is disclosed;

[0098] Figure 7 A schematic diagram of temperature monitoring points of an IGBT module according to an embodiment of the present invention is disclosed;

[0099] Figure 8 Disclosed is a speed and current operation diagram of a train station spacing according to an embodiment of the present invention;

[0100] Fig. 9 A schematic diagram of cycle life calculation according to an embodiment of the present invention is disclosed.

[0101] The meanings of the reference numerals in the figures are as follows:

[0102] 511 FWD chip;

[0103] 512 IGBT chips;

[0104] 521 upper solder layer;

[0105] 522 upper copper layer;

[0106] 530 Ceramic layer;

[0107] 541 lower copper layer;

[0108] 542 lower solder layer;

[0109] 550 substrate;

[0110] 560 thermal interface material layer;

[0111] 570 Radiator;

[0112] 571 water inlet;

[0113] 572 Water outlet. DETAILED DESCRIPTION

[0114] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the invention and are not used to limit the invention.

[0115] The present invention proposes a traction converter cooling system design method based on the actual line operating conditions of a train, and more particularly involves life calculation and life design of traction converter power devices according to the actual line route of the train, thereby optimizing the traction converter cooling system based on the life calculation results.

[0116] Figure 1 A step diagram of a method for designing a cooling system for a train traction converter according to an embodiment of the present invention is disclosed. Figure 1 As shown, a method for designing a cooling system for a train traction converter proposed by the present invention comprises the following steps:

[0117] Step S1, obtaining train line operation data;

[0118] Step S2, calculating the power device loss of the traction converter according to the train line operation data;

[0119] Step S3, calculating the junction temperature of the power device by combining the cooling system parameters of the traction converter and the calculation result of the power device loss of the traction converter;

[0120] Step S4, calculating the life of the power device according to the calculation result of the junction temperature of the power device;

[0121] Step S5, optimizing the design of cooling system parameters based on the life calculation result of the power device, and repeating the power device junction temperature and life calculation until the life calculation result of the power device meets the design life requirement.

[0122] The present invention proposes a method for designing a train traction inverter cooling system, which calculates power device losses based on train line operation data, and calculates junction temperature based on traction inverter cooling system parameters, obtains matrix data for power device junction temperature calculation, and then calculates power device life based on the matrix data, thereby realizing IGBT life calculation and optimal design of traction inverter cooling system parameters.

[0123] In this embodiment, the power device of the traction converter is an IGBT module.

[0124] The IGBT module is a modular semiconductor product that is packaged by connecting an IGBT chip and a FWD (Freewheeling diode) chip through a specific circuit bridge.

[0125] IGBT (Insulated Gate Bipolar Transistor) chip is a composite fully controlled voltage-driven power semiconductor device composed of BJT (bipolar junction transistor) and MOS (insulated gate field effect transistor). It has the advantages of both the high input impedance of MOSFET and the low on-state voltage drop of GTR (high power transistor).

[0126] Figure 2 A flow chart of a method for designing a cooling system for a train traction converter according to an embodiment of the present invention is disclosed. Figure 1 and Figure 2 , the above steps of the present invention will be described in detail. It should be understood that within the scope of the present invention, the above technical features of the present invention and the technical features specifically described below (such as embodiments) can be combined with each other and related to each other to form a preferred technical solution.

[0127] Step S1, obtaining train line operation data.

[0128] First, extract the line operation curve of the train. When the train is running, there will be acceleration, constant speed, and deceleration in an operation section. Each acceleration and deceleration will cause the IGBT temperature rise to increase and decrease.

[0129] Figure 3 A schematic diagram of train operation data according to an embodiment of the present invention is disclosed. Specifically, Figure 3 The current data of a train running on a certain line section is presented. The horizontal axis in the figure represents time, and the vertical axis represents the voltage V of the traction converter, which uses the system application value. The train operation data includes the current I and voltage V on the input and output sides of the converter, the train running time t, and speed information. Usually, these data are used for analysis of the converter input end.

[0130] Step S2, calculating the power device loss of the traction converter according to the train line operation data.

[0131] The power devices of traction converters include insulated gate bipolar transistors (IGBTs), thyristors, gate turn-off thyristors (GTOs), and silicon carbide metal oxide semiconductor field effect transistors (SiC-MOSFETs).

[0132] In this embodiment, the power device is an IGBT module, and the IGBT module includes a plurality of IGBT chips and a FWD chip:

[0133] As a switching device, the IGBT module cyclically switches between various static and dynamic states when working. During this process, the IGBT will generate static loss and dynamic loss, which constitute the total loss of the semiconductor module and cause the IGBT module to heat up.

[0134] Figure 4 The IGBT module loss composition diagram according to an embodiment of the present invention is disclosed. Figure 4 As shown, the IGBT module is a high voltage IGBT (HVIGBT) module, and the IGBT module loss includes the IGBT chip loss P T and FWD chip loss P D .

[0135] The IGBT chip loss P T Including IGBT steady-state loss P sat and IGBT switching loss P on+off , IGBT chip loss P T The corresponding expression is:

[0136] P T =P sat +P on+off .

[0137] Among them, IGBT steady-state loss P sat , the corresponding expression is as follows:

[0138]

[0139] IGBT switching loss P on+off , the corresponding expression is as follows:

[0140]

[0141] Where D is the duty cycle, MR is the modulation depth, and θ is the initial phase angle;

[0142] V CE(sat) is the collector (C)-emitter (E) saturation voltage;

[0143] I CP The current sensor tests the current peak value of the effective value for the current passing through the IGBT chip;

[0144] x is the phase angle, which is the phase of the traction transformer and is sampled by the internal device;

[0145] P sw(on) is the turn-on loss of the IGBT chip. The turn-on loss varies with the current. is the IGBT parameter of the IGBT module, obtained from the device manufacturer's manual;

[0146] P sw(off) This is the turn-off loss of the IGBT chip. The turn-on loss also varies with the current.

[0147] IGBT parameters of the IGBT module are obtained from the device manufacturer's manual;

[0148] f c is the switching frequency of the IGBT module.

[0149] The “@” in the formula is a common formula symbol used by those skilled in the art, and A(@B) represents A under the condition that B is limited.

[0150] The FWD chip loss P D Including FWD steady-state loss P F and FWD reverse recovery loss P rr , the corresponding expression is:

[0151] P D =P F +P rr ;

[0152] Among them, FWD steady-state loss P F , the corresponding expression is as follows:

[0153]

[0154] FWD reverse recovery loss P rr , the corresponding expression is as follows:

[0155]

[0156] Where MR is the modulation depth, θ is the initial phase angle, V CC is the intermediate voltage;

[0157] x is the phase angle;

[0158] I CP is the current passing through the IGBT chip, and is the current peak value of the effective value of the current extracted during train operation;

[0159] I rr is the reverse recovery current, is the operating parameter of the FWD chip, obtained from the device manufacturer's manual;

[0160] t rr is the reverse recovery time, which is the operating parameter of the FWD chip, obtained from the device manufacturer's manual;

[0161] f c is the switching frequency of the IGBT module;

[0162] V EC is the forward voltage of the diode, and is the operating parameter of the FWD chip, which is obtained from the device manufacturer's manual.

[0163] Step S3, calculating the junction temperature of the power device by combining the cooling system parameters of the traction converter and the calculation result of the power device loss of the traction converter.

[0164] Furthermore, the step S3 further includes designing parameters of a cooling system of the traction converter.

[0165] The parameters of the cooling system of the traction converter are related to the cooling method adopted, which includes but is not limited to water cooling, air cooling, running air cooling, heat pipe cooling and forced air cooling.

[0166] In this embodiment, taking a water-cooled traction inverter as an example, the radiator method also uses a water-cooled radiator structure to illustrate the parameters of the traction inverter cooling system. This method is also applicable to traction inverters with other cooling methods such as running air cooling, heat pipe cooling, and forced air cooling.

[0167] Water cooling is also called liquid cooling. The principle of water cooling is very simple: in a closed liquid circulation device, the power generated by the pump drives the liquid circulation in the closed system. The radiator is the heat absorbing and dissipating component. The radiator transfers the heat generated by the IGBT module to a larger heat exchanger through the circulation of the liquid, and the fan cools the heat exchanger for heat dissipation.

[0168] The cooled liquid flows back to the radiator and other equipment, and the cycle repeats itself.

[0169] The parameters of the cooling system of the traction converter involve the thermal resistance design of the water-cooled radiator, the selection of the pump, the selection of the fan and the design of the cooling system piping system.

[0170] The cooling system of the traction converter is represented by a multivariate function f:

[0171] y=f(x1,x2,...x5);

[0172] x1: Radiator parameters. The thermal resistance design of the radiator includes related parameters such as flow rate, flow resistance, heat generation, and thermal resistance.

[0173] x2: Pump parameters, including pump head, flow rate and other parameters, radiator parameters, heat exchanger parameters, and cooling system pipeline resistance;

[0174] x3: Fan parameters, which include flow rate and resistance. The selection of fan parameters is related to the heat exchanger parameters.

[0175] x4: heat exchanger parameters, including flow rate, air volume, flow resistance and heat dissipation;

[0176] x5: Cooling system pipeline resistance, mainly including resistance of quick connectors, pipelines, various functional valves (flow control valves), filters, other pipe joints, etc.

[0177] As an important part of the water cooling system, the cold plate is mainly used to fully exchange the heat generated by the heat-generating components with the coolant. In order to ensure that the heat dissipated by the heat-generating surface of the device can be taken away as much as possible when being cooled by the liquid, the contact between the device and the cold plate and the thermal resistance of the cold plate are particularly important.

[0178] To design a proper cold plate, the following parameters need to be determined: cooling liquid flow rate, cooling liquid inlet temperature, heat dissipation power of the heat generating device mounted on the cold plate, and the maximum allowable temperature Tmax of the cold plate surface. Knowing these parameters, the maximum allowable thermal resistance of the cold plate can be determined and verified through thermal simulation analysis.

[0179]

[0180] T out : Cooling liquid outlet temperature;

[0181] T in : Cooling liquid inlet temperature;

[0182] Q: Total heat dissipation power of the heat generating devices on the cold plate;

[0183] ρ: density of liquid;

[0184] v: cooling liquid flow rate;

[0185] Cp : Specific heat capacity of the cooling liquid.

[0186] After determining the above parameters, calculate the flow resistance of the radiator (if it is an air-cooled radiator, it is the wind resistance).

[0187] Pipeline systems and valves are important components of the water cooling system hardware, mainly including quick connectors, pipes, various functional valves (flow control valves), filters, other pipe joints and seals.

[0188] The size of the pipe (such as diameter, length, etc.) is determined according to the flow rate of the coolant:

[0189]

[0190] Among them, Q v is the water flow rate (m3 / h); v is the water flow velocity (m / s).

[0191] After calculating the flow rate, the resistance of quick connectors, pipes, various functional valves (flow control valves), filters, and other pipe joints can be determined. The sum of the above resistances is the cooling system pipe resistance.

[0192] Coolant: The coolant's heat transfer capacity, freezing point and viscosity, boiling point and decomposition temperature, insulating properties, corrosiveness, flammability, toxicity, cost, etc. must be considered.

[0193] The pump is an important part of the cooling system. Its purpose is to circulate the coolant at a flow rate required to overcome the total fluid friction heat in the cooling circuit. The parameters of the pump mainly include the flow rate Q required by the cooling system. v And pressure head H.

[0194] Fan parameters include flow rate, resistance, and the selection of fan parameters is related to the heat exchanger parameters and the cooling system structure of the system.

[0195] Heat exchanger parameters include flow rate, air volume, flow resistance and heat dissipation.

[0196] Furthermore, the step S3 further includes calculating the junction temperature of the power device.

[0197] In this embodiment, the step S3 further includes:

[0198] Get the IGBT module shell temperature (casing temperature) Tc;

[0199] IGBT chip junction temperature T based on traction converter cooling system parameters j(T) Calculation, and

[0200] Based on the parameters of the traction converter cooling system, the FWD chip junction temperature T j(D)calculate.

[0201] The power device junction temperature refers to the temperature rise caused by the loss of the internal chip of the IGBT module when performing switching actions. After obtaining the loss of the IGBT chip and the FWD chip, the average junction temperature of the IGBT chip and the FWD chip is calculated using the thermal resistance equivalent model.

[0202] Figure 5 A thermal equivalent model diagram of an IGBT module according to an embodiment of the present invention is disclosed. Figure 5 The thermal resistance equivalent model shown can help analyze the thermal coupling between multiple IGBT modules, that is, the influence of mutual heating and heat dissipation when multiple chips work in parallel, so as to determine the design requirements of the overall cooling system.

[0203] Figure 5 The leftmost 1-N represents N IGBT modules of the same heat sink, each of which includes a FWD chip and an IGBT chip;

[0204] In each IGBT module consisting of an IGBT and FWD chip, heat flows from Tj (junction temperature) through the thermal resistance from junction to case (R th(j-c)D or R th(j-c)T ), reaching the shell temperature Tc.

[0205] Then, the heat is transferred through R th(c-f)T Further conducted to the heat sink temperature Tf.

[0206] Finally, through R th(f-a) , heat is transferred to the inlet water temperature Ta of the cooling system.

[0207] Among them, T j-FWD is the junction temperature of the FWD chip, T j-IGBT is the junction temperature of the IGBT chip; Tc is the case temperature;

[0208] Tf is the temperature of the heat sink under the IGBT module;

[0209] Ta is the inlet side temperature of the cooling system radiator;

[0210] R th(j-c)D is the thermal resistance between the junction temperature and the case temperature of the FWD chip;

[0211] R th(j-c)T It is the thermal resistance between the junction temperature and the case temperature of the IGBT chip;

[0212] R th(c-f)T It is the equivalent thermal resistance of the thermal conductive silicone grease between the IGBT module base plate (substrate) and the heat sink, that is, the thermal resistance from the shell temperature to the heat sink temperature, which describes the heat conduction process from the IGBT module base plate to the heat sink;

[0213] R th(f-a) is the thermal resistance of the radiator itself, describing the heat conduction process from the radiator temperature Tf position to the cooling system radiator inlet side temperature Ta position.

[0214] Through Figure 5 The thermal equivalent model shown can accurately simulate the heat distribution of multiple power devices and analyze the relationship between junction temperature, case temperature, heat sink temperature and cooling system inlet temperature, which helps to optimize the design of the cooling system, ensure that all modules operate within a safe temperature range, and extend the service life of power devices.

[0215] Figure 6 A schematic diagram of the heat sink temperature according to an embodiment of the present invention is disclosed. Figure 6 As shown, the IGBT module structure includes:

[0216] The FWD chip 511 and the IGBT chip 512 are core parts of the IGBT module, and these chips are mounted on a DBC (direct bond copper) ceramic layer 530 .

[0217] The upper solder layer 521 is used to connect the FWD chip 511, the IGBT chip 512 and the ceramic layer 530, and provide an electrical and thermal conduction path. The upper copper layer 522 is located between the upper solder layer 521 and the ceramic layer 530, and can be used as a metal layer for structural support and thermal conduction.

[0218] The ceramic layer 530 is located below the chip and plays a role of electrical insulation and thermal conduction, and conducts the heat generated by the chip to the substrate 550 below.

[0219] The lower copper layer 541 is located between the lower solder layer 542 and the ceramic layer 530, and as a metal layer, can be used for structural support and heat conduction. The lower solder layer 542 is used to connect the ceramic layer 530 and the substrate 550, providing an electrical and thermal conduction path;

[0220] The substrate 550 is a metal substrate, and a heat sink 570 is connected below to further transfer heat to the heat sink 570 below;

[0221] The thermal interface material (TIM) layer 560 is used to fill the tiny gap between the substrate 550 and the heat sink 570 to improve the heat conduction efficiency. In this embodiment, the thermal interface material layer 560 is thermal conductive silicone grease.

[0222] The radiator 570 includes a water inlet 571 and a water outlet 572 for the flow of cooling liquid to remove heat.

[0223] The heat sink 570 design of the cooling system is crucial to the thermal management of the IGBT module. By optimizing the heat sink design and the flow of the coolant, the temperature inside the module can be effectively controlled, and the efficiency and reliability of the module can be improved.

[0224] Figure 6 The junction temperature T of the FWD chip is marked respectively. j-FWD And the junction temperature T of the IGBT chip j-IGBT . Figure 6 The case temperature Tc is also marked, and its location is on the base plate 550 of the IGBT module bottom plate, directly below the chip. The heat sink temperature is located on the surface of the heat sink 570 Tf, corresponding to the case temperature Tc.

[0225] Heat transfer starts from the chip (Tj), first passes through the ceramic layer 530 to the substrate 550, forming a shell temperature Tc. Then, the heat continues to be transferred from the substrate 550 to the heat sink 570, and the temperature drops to the heat sink temperature Tf. Finally, the heat is taken away by the cooling water circulation of the heat sink 570. Water enters the heat sink 570 from the water inlet 571, heats up during the heat dissipation process, and is discharged from the water outlet 572. The inlet side temperature of the water inlet 571 is Ta.

[0226] In actual applications, the interior of an IGBT module may be composed of multiple chips connected in parallel, and the temperature of the corresponding points of each chip will be different.

[0227] Figure 7 A schematic diagram of temperature monitoring points of an IGBT module according to an embodiment of the present invention is disclosed. Figure 7 As shown, the IGBT module includes multiple IGBT (insulated gate bipolar transistor) and FWD (diode) chips, which are arranged on the device substrate to form a parallel structure. The shell temperature Tc at the bottom of the chip includes shell temperature Tc1, shell temperature Tc2 and shell temperature Tc3, and the heat sink temperature Tf on the surface of the heat sink 570 includes heat sink temperature Tf1, heat sink temperature Tf2 and heat sink temperature Tf3.

[0228] Figure 7 The upper part of the diagram is a temperature distribution diagram, showing the temperature difference inside the module, where Tj(av) is the average junction temperature of the chip, Tc(av) is the average case temperature, Tf(av) is the average heat sink temperature, dTj-c is the temperature difference between the junction temperature and the case temperature, and dTc-f is the temperature difference between the case temperature and the heat sink. Through these temperature measurements and analyses, the temperature distribution inside the multi-chip IGBT module can be evaluated, the impact of thermal coupling effects on temperature can be identified, and the design of the cooling system can be optimized to reduce the temperature difference and balance the temperature distribution, thereby improving the service life and reliability of the IGBT module.

[0229] The junction temperature of different IGBT and FWD chips may be different. When multiple chips are connected in parallel, multiple IGBT chips and FWD chips often work at the same time, and each chip will heat each other from all directions to form thermal coupling. The effect of thermal coupling cannot be ignored. Actual tests show that the temperature after thermal coupling is higher than the temperature without thermal coupling.

[0230] Since the thermal coupling effect is closely related to the chip spacing and the copper base thickness, after considering the thermal coupling effect, the equivalent thermal resistance R of the thermal grease between the IGBT module base plate (substrate) and the heat sink is th(c-f)T热耦合 , the corresponding expression is:

[0231]

[0232] Among them, R th(c-f)T测试值 It is the test value when the IGBT chip or FWD chip is working;

[0233] k1 is the chip coupling coefficient, which is related to the chip layout;

[0234] k2 is the substrate coupling coefficient, which is related to the substrate material;

[0235] S is the chip distance and D is the substrate thickness.

[0236] It should be noted that, in this embodiment, the shell temperature Tc is obtained by calculation. In other embodiments, the shell temperature Tc can also be obtained by other methods such as sensor measurement.

[0237] Furthermore, based on the traction converter cooling system parameters, the IGBT module case temperature Tc is calculated.

[0238] In this embodiment, after considering the effect of thermal coupling, the calculation formulas of the IGBT module case temperature Tc are as follows:

[0239] T C =(P T +P D )×R th(c-f)T热耦合 +(P T +P D )×R th(f-a) +Ta;

[0240] Among them, R th(c-f)T热耦合 It is the equivalent thermal resistance of the thermal grease between the IGBT module base plate and the heat sink after considering the thermal coupling effect;

[0241] R th(f-a) is the thermal resistance of the heat sink itself;

[0242] Ta is the temperature of the heat sink below the IGBT module;

[0243] P T is the IGBT chip loss;

[0244] P D FWD chip loss.

[0245] Furthermore, the IGBT chip junction temperature T j(T) Calculation. FWD chip junction temperature T based on traction converter cooling system parameters j(D) calculate.

[0246] Based on the above equivalent thermal resistance R th(c-f)T热耦合 After considering the effect of thermal coupling, the junction temperature T of the IGBT chip inside the IGBT module j(T) and the junction temperature of the FWD chip inside the IGBT module T j(D) The calculation formulas are as follows:

[0247] T j(T) =P T ×R th(j-c)T +T C =P T ×R th(j-c)T +(P T +P D )×R th(c-f)T热耦合 +(P T +P D )×R th(f-a) +Ta;

[0248] T j(D) =P D ×R th(j-c)D +T C =P D ×R th(j-c)D +(P T +P D )×R th(c-f)T热耦合 +(P T +P D )×R th(f-a) +Ta;

[0249] Among them, R th(j-c)D is the thermal resistance between the junction temperature and the case temperature of the FWD chip, obtained from the device manufacturer's manual;

[0250] R th(j-c)T is the thermal resistance between the junction temperature and the case temperature of the IGBT chip, obtained from the device manufacturer's manual;

[0251] R th(c-f)T热耦合 It is the equivalent thermal resistance of the thermal grease between the IGBT module base plate and the heat sink after considering the thermal coupling effect;

[0252] Rth(f-a) It is the thermal resistance of the radiator itself, which is related to the material, shape, and heat dissipation method of the radiator;

[0253] Tf is the temperature of the heat sink below the IGBT module;

[0254] Tc is the case temperature below the IGBT module;

[0255] P T is the IGBT chip loss;

[0256] P D FWD chip loss.

[0257] Step S4, calculating the life of the power device according to the calculation result of the junction temperature of the power device.

[0258] IGBT fatigue failure is caused by repeated electrical stress and thermal stress shocks to the solder layer, connecting solder joints, bonding wires, etc. inside the module package during application. The thermal expansion coefficients of the various layers of materials inside the module are different, and the temperature changes frequently during operation. The repeated impact of temperature fluctuations causes the bonding wires to detach from the bonding points, the metal layer on the chip surface to crack, and the solder layer inside the module package to crack, void and delamination, thereby reducing the life and reliability of the device. Therefore, accurately calculating the life of the IGBT module is crucial to achieving refined research and development.

[0259] There are two main factors that affect the life of IGBT, which are power cycle life damage and thermal cycle life damage. The damage of power cycle life loss mainly occurs at the connection between the silicon chip and the bonding wire. The damage point of thermal cycle life loss is located at the welding layer between the base plate and the insulation layer.

[0260] The biggest factor affecting the life of the module is the junction temperature fluctuation. The entire operating cycle contains different junction temperature fluctuations. Different junction temperature fluctuations can be decomposed and simplified into load cycles with different fluctuation amplitudes.

[0261] In this embodiment, the calculation of the life of the power device according to the calculation result of the junction temperature of the power device further includes:

[0262] The temperature variation operating matrix junction temperature of the IGBT module is calculated, and the life of the IGBT module is calculated based on the matrix data.

[0263] Figure 8 The speed and current operation diagram of a train station spacing according to an embodiment of the present invention is disclosed, such as Figure 8 As shown in the figure, by importing the train operation data, the IGBT module loss can be calculated, and the internal junction temperature change data can be further calculated based on the parameters of the traction converter cooling system. The internal junction temperature change data is calculated based on the traction converter cooling system parameters, and the shell temperature change ΔT of the IGBT module is calculated.c Operation matrix, IGBT chip operation junction temperature change ΔT jT Operation matrix and FWD operation junction temperature change ΔT jD The operation matrix.

[0264] The operating temperature matrix refers to the collection of multiple temperature changes and corresponding cycle numbers experienced by the IGBT module during operation.

[0265] IGBT module case temperature change ΔT cT The operation matrix is ​​as follows:

[0266]

[0267] Where, ΔT c1 , ΔT c2 , ΔT c3 and ΔT cn There are n shell temperature changes, and the corresponding number of cycles is n c1 、n c2 、n c3 and n cn .

[0268] IGBT chip operating junction temperature change ΔT jT The operation matrix is ​​as follows:

[0269]

[0270] Where, ΔT jT1 , ΔT jT2 , ΔT jT3 and ΔT jTn is the junction temperature change of n types of IGBT chips and the corresponding number of cycles n jT1 、n jT2 、n jT3 and n jTn .

[0271] FWD chip operating junction temperature change ΔT jD The operation matrix is ​​as follows:

[0272]

[0273] Where, ΔT jD1 , ΔT jD2 , ΔT jD3 and ΔT jDn is the junction temperature change of n types of FWD chips and the corresponding number of cycles n jD1 、n jD2 、n jD3 and n jDn .

[0274] The life of IGBT modules is determined by material fatigue caused by repeated temperature cycle stress. The operating temperature matrix describes the amplitude of different temperature changes experienced by the device during operation, and each temperature change amplitude corresponds to a specific fatigue cycle life.

[0275] Fig. 9 A schematic diagram of cycle life calculation according to an embodiment of the present invention is disclosed, such as Fig. 9 As shown, the ΔT in the figure can be ΔT c , ΔT jT or ΔT jD Any one of them can be used to calculate the corresponding cycle life of the IGBT module.

[0276] The relationship between the temperature change amplitude and the corresponding number of cycles can be used to determine the cycle life of the IGBT module under different temperature change conditions. c , ΔT jT , ΔT jD ), the corresponding cycle life value of the IGBT module can be read in the cycle life curve.

[0277] According to the actual operation process ΔT c , ΔT jT , ΔT jD The fluctuation peak value, especially the relationship between the amplitude and the corresponding number of cycles, is read out from the cycle life curve corresponding to the IGBT module, thereby calculating the life of the IGBT module.

[0278] Furthermore, the IGBT module ΔT c The cumulative lifespan calculation formula is as follows:

[0279]

[0280] Among them, L (ΔTc) It refers to the IGBT module at the shell temperature T c Cumulative life under cyclic variation conditions;

[0281] n ci It means that under different shell temperature change cycles, the IGBT module is under a certain temperature difference ΔT ci The number of cycles in the case;

[0282] N ci Indicates the corresponding temperature difference ΔT ci The rated life or maximum allowable number of cycles of the IGBT module.

[0283] Furthermore, the IGBT module ΔT jT The cumulative lifespan calculation formula is as follows:

[0284]

[0285] in, Refers to the cumulative life of the IGBT module under the condition of cyclic changes in the junction temperature of the IGBT chip;

[0286] n jTi It means that under different IGBT chip junction temperature change cycles, the IGBT module is under a certain temperature difference ΔT jTi The number of cycles in the case;

[0287] N jTi Indicates the corresponding temperature difference ΔT jTi The rated life or maximum allowable number of cycles of the IGBT module.

[0288] Furthermore, the IGBT module ΔT jD The cumulative lifespan calculation formula is as follows:

[0289]

[0290] in, Refers to the cumulative life of the IGBT module under the condition of cyclic changes in the junction temperature of the FWD chip;

[0291] n jDi It means that under different FWD chip junction temperature change cycles, the IGBT module is under a certain temperature difference ΔT jDi The number of cycles in the case;

[0292] N jDi Indicates the corresponding temperature difference ΔT jDi The rated life or maximum allowable number of cycles of the IGBT module.

[0293] Step S5, optimizing the design of cooling system parameters based on the life calculation result of the power device, and repeating the power device junction temperature and life calculation until the life calculation result of the power device meets the design life requirement.

[0294] Calculate the ΔT of the IGBT c , ΔT jT or ΔT jD Lifespan: If the calculated results of IGBT lifespan do not meet the design requirements, modify the traction converter cooling system parameters and perform the calculation again until the optimal design of IGBT design lifespan and traction converter cooling system parameters is achieved.

[0295] Although the above methods are illustrated and described as a series of actions for simplicity of explanation, it should be understood and appreciated that these methods are not limited by the order of the actions, because according to one or more embodiments, some actions may occur in a different order and / or concurrently with other actions from those illustrated and described herein or not illustrated and described herein but understandable to those skilled in the art.

[0296] The present invention proposes a train traction inverter cooling system design method based on the actual operating conditions of the train. The life calculation and life design of the traction inverter power devices are performed based on the actual line route operating conditions of the train, and the cooling system parameters of the traction inverter are optimized and designed. The cooling system parameters and IGBT life and other factors are comprehensively considered to achieve comprehensive optimization and matching of the traction inverter cooling system, thereby ensuring the safe and stable operation of the equipment while extending the service life of key components such as IGBT, ultimately achieving the purpose of improving the overall system performance and reliability.

[0297] Those skilled in the art will appreciate that information, signals, and data may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips cited throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or optical particles, or any combination thereof.

[0298] Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or a combination of the two. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. The technician may implement the described functionality in different ways for each specific application, but such implementation decisions should not be interpreted as resulting in a departure from the scope of the present invention.

[0299] The various illustrative logic modules and circuits described in conjunction with the embodiments disclosed herein may be implemented or executed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in cooperation with a DSP core, or any other such configuration.

[0300] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor so that the processor can read and write information from / to the storage medium. In an alternative, a storage medium may be integrated into a processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and the storage medium may reside in a user terminal as discrete components.

[0301] As shown in this application and claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0302] The above embodiments are provided for persons familiar with the art to implement or use the present invention. Personnel familiar with the art can make various modifications or changes to the above embodiments without departing from the inventive concept of the present invention. Therefore, the protection scope of the present invention is not limited to the above embodiments, but should be the maximum scope of the innovative features mentioned in the claims.

Claims

1. A method for designing a cooling system for a train traction converter, characterized in that: The following steps are involved: Obtain train line operation data; Calculate the power device losses of the traction converter based on the train line operation data; Calculate the junction temperature of the power device by combining the cooling system parameters of the traction converter with the calculation results of the power device loss of the traction converter; Calculate the life of the power device based on the junction temperature calculation results of the power device; The cooling system parameters are optimized based on the life calculation results of the power device, and the junction temperature and life calculation of the power device are repeated until the life calculation results of the power device meet the design life requirements.

2. The train traction converter cooling system design method according to claim 1, characterized in that: The train line operation data is the train full line operation data; The train line operation data includes the current and voltage on the input side of the converter, the current and voltage on the output side, and the train running time and speed.

3. The train traction converter cooling system design method according to claim 1, characterized in that: The parameters of the traction converter cooling system are related to the cooling method adopted, and the cooling method includes water cooling, air cooling, running air cooling, heat pipe cooling and forced air cooling.

4. The train traction converter cooling system design method according to claim 3, characterized in that: The cooling method is water cooling, and the traction converter cooling system parameters include radiator parameters, pump parameters, fan parameters, heat exchanger parameters and cooling system pipeline resistance.

5. The method for designing a cooling system for a train traction converter according to claim 4, characterized in that: The traction converter cooling system includes a water cooling plate; The parameters of the traction converter cooling system include cooling liquid flow rate, cooling liquid inlet temperature, heat dissipation power of heat generating devices installed on the water cooling plate, the maximum allowable temperature of the water cooling plate surface and the maximum allowable thermal resistance of the water cooling plate.

6. The train traction converter cooling system design method according to claim 1, characterized in that: The power device is an IGBT module, and the IGBT module includes a plurality of IGBT chips and a FWD chip.

7. The method for designing a cooling system for a train traction converter according to claim 6, characterized in that: The IGBT module loss includes the IGBT chip loss P T ; The IGBT chip loss P T Including IGBT steady-state loss P sat and IGBT switching loss P on+off ; IGBT steady-state loss P sat , the corresponding expression is as follows: IGBT switching loss P on+off , the corresponding expression is as follows: Where D is the duty cycle, MR is the modulation depth, and θ is the initial phase angle; V CE(sat) is the collector (C)-emitter (E) saturation voltage; I CP The current sensor tests the current peak value of the effective value for the current passing through the IGBT chip; x is the phase angle; P sw(on) is the turn-on loss of the IGBT chip; P sw(off) is the turn-off loss of the IGBT chip; f c is the switching frequency of the IGBT module.

8. The method for designing a cooling system for a train traction converter according to claim 6, characterized in that: The IGBT module loss FWD chip loss P D ; The FWD chip loss P D Including FWD steady-state loss P F and FWD reverse recovery loss P rr ; FWD steady-state loss P F , the corresponding expression is as follows: FWD reverse recovery loss P rr , the corresponding expression is as follows: Where MR is the modulation depth, θ is the initial phase angle, V CC is the intermediate voltage; x is the phase angle; I CP is the current passing through the IGBT chip, and is the current peak value of the effective value of the current extracted during train operation; I rr is the reverse recovery current, which is the operating parameter of the FWD chip; t rr is the reverse recovery time, which is the action parameter of the FWD chip; f c is the switching frequency of the IGBT module; V EC is the forward voltage of the diode and is the operating parameter of the FWD chip.

9. The method for designing a cooling system for a train traction converter according to claim 6, characterized in that: The step of calculating the junction temperature of the power device by combining the cooling system parameters of the traction converter with the calculation results of the power device loss of the traction converter further comprises: Get the IGBT module case temperature Tc; IGBT chip junction temperature T based on traction converter cooling system parameters j(T) Calculation, and Based on the parameters of the traction converter cooling system, the FWD chip junction temperature T j(D) calculate.

10. The method for designing a cooling system for a train traction converter according to claim 9, characterized in that: The calculation formula of the IGBT module case temperature Tc is as follows: T C (P T +P D )×R th(c-f)T热耦合 +(P T +P D )×R th(f-a) +Ta: Among them, R th(c-f)T热耦合 It is the equivalent thermal resistance of the thermal grease between the IGBT module base plate and the heat sink after considering the thermal coupling effect; R th(f-a) is the thermal resistance of the heat sink itself; Ta is the temperature of the heat sink below the IGBT module; P T is the IGBT chip loss; P D FWD chip loss.

11. The method for designing a cooling system for a train traction converter according to claim 9, characterized in that: The junction temperature T of the IGBT chip inside the IGBT module j(T) and FWD chip junction temperature T j(D) The calculation formulas are as follows: T j(T) =P T ×R th(j-c)T +T C ; T j(D) =P D ×R th(j-c)D +T C ; Among them, R th(j-c)D is the thermal resistance between the junction temperature and the case temperature of the FWD chip; R th(j-c)T It is the thermal resistance between the junction temperature and the case temperature of the IGBT chip; Tc is the case temperature below the IGBT module; P T is the IGBT chip loss; P D FWD chip loss.

12. The method for designing a cooling system for a train traction converter according to claim 10, characterized in that: The equivalent thermal resistance R of the thermal grease between the IGBT module base plate and the heat sink after considering the thermal coupling effect th(c-f)T热耦合 , the corresponding expression is: Among them, R th(c-f)T测试值 It is the test value when the IGBT chip or FWD chip is working; k1 is the chip coupling coefficient; k2 is the substrate coupling coefficient; S is the chip distance, and D is the substrate thickness.

13. The method for designing a cooling system for a train traction converter according to claim 9, characterized in that: The calculating the life of the power device according to the calculation result of the junction temperature of the power device further includes: The temperature variation operating matrix junction temperature of the IGBT module is calculated, and the life of the IGBT module is calculated based on the matrix data.

14. The method for designing a cooling system for a train traction converter according to claim 13, characterized in that: The calculation obtains the temperature variation operation matrix junction temperature of the IGBT module, and performs IGBT module life calculation based on the matrix data, further comprising: Calculate the case temperature change ΔT of the IGBT module c Operation matrix, IGBT operation junction temperature change ΔT jT Operation matrix and FWD operation junction temperature change ΔT jD The operation matrix of According to the actual operation process ΔT c , ΔT jT , ΔT jD The relationship between the amplitude of temperature change and the corresponding number of cycles is obtained by obtaining the corresponding cycle life value in the cycle life curve corresponding to the IGBT module, thereby calculating the life of the IGBT module.

15. The method for designing a cooling system for a train traction converter according to claim 14, characterized in that: The IGBT module ΔT c The cumulative lifespan calculation formula is as follows: IGBT module ΔT jT The cumulative lifespan calculation formula is as follows: IGBT module ΔT jD The cumulative lifespan calculation formula is as follows: in, Refers to the cumulative life of the IGBT module under the condition of cyclic changes in the junction temperature of the IGBT chip; Refers to the cumulative life of the IGBT module under the condition of cyclic changes in the junction temperature of the FWD chip; L (ΔTc) It refers to the IGBT module at the shell temperature T c Cumulative life under cyclic variation conditions; n jTi It means that under different IGBT chip junction temperature change cycles, the IGBT module is under a certain temperature difference ΔT jTi The number of cycles in the case; n jDi It means that under different FWD chip junction temperature change cycles, the IGBT module is under a certain temperature difference ΔT jDi The number of cycles in the case; n ci It means that under different shell temperature change cycles, the IGBT module is under a certain temperature difference ΔT ci The number of cycles in the case; N jTi Indicates the corresponding temperature difference ΔT jTi Under this condition, the rated life or maximum permissible number of cycles of the IGBT module; N jDi Indicates the corresponding temperature difference ΔT jDi Under this condition, the rated life or maximum permissible number of cycles of the IGBT module; N ci Indicates the corresponding temperature difference ΔT ci The rated life or maximum allowable number of cycles of the IGBT module.

Images