Estimation method for monitoring junction temperature of IGBT module

Abstract

The invention discloses an estimation method for monitoring the junction temperature of an IGBT module, and the method comprises the following steps: 1), building a third-order Foster thermal network model, and obtaining a third-order self-heating thermal resistance constant, a third-order mutual-heating thermal resistance constant and a third-order heat transfer time constant; 2) collecting phase voltage, phase current and junction temperature of each phase; (3) micro switching states of the IGBTs and the FRDs are judged, and the PWM switching frequency and the duty ratio are obtained; 4) calculating turn-on loss, turn-off loss and turn-on loss of each IGBT and reverse recovery loss and turn-on loss of the FRD; calculating the loss of the metal bonding wire; 5) calculating the total loss of each IGBT and each FRD; 6) calculating the total temperature rise of each IGBT and each FRD; 7) calculating the total temperature difference from each phase NTC temperature sensor to the cooling liquid; 8) calculating the cooling liquid temperature of each phase, and estimating the estimated junction temperature of each IGBT and each FRD; and 9) detecting the real-time junction temperature, comparing the real-time junction temperature with the estimated junction temperature, if the estimated junction temperature is within the error range, determining that the estimated junction temperature is the final junction temperature, and if the estimated junction temperature is not within the error range, performing correction, and repeating the steps 3-9) until the estimated junction temperature is within the error range.

Description

Technical Field

[0001] The present invention relates to the field of IGBTs, and in particular to an estimation method for monitoring junction temperature of an IGBT module. Background Art

[0002] The power semiconductor devices of new energy vehicles are the core components for controlling the drive motor. Currently, insulated gate bipolar transistors (IGBTs) are widely used in power semiconductor devices. Power semiconductor devices generate a lot of heat during operation, which can easily lead to damage and failure due to overheating. Therefore, real-time monitoring of the junction temperature of the IGBT chip and ensuring the thermal safety performance of the power semiconductor device are important factors in ensuring the safety of the motor controller.

[0003] In the prior art, the IGBT module includes six IGBT chips, six FRD diodes, and three NTC temperature sensors. Each phase includes two IGBT chips on the upper and lower bridges, two FRD diodes on the upper and lower bridges, and one NTC temperature sensor. The NTC temperature sensor is generally installed next to the upper bridge IGBT chip of each phase, and is used to collect temperature to characterize the temperature status of the IGBT chip of each phase. However, in actual applications, the temperature collected by the NTC temperature sensor is not the real real-time junction temperature of the surface of the IGBT chip, and the response rate of the temperature collected by the NTC temperature sensor is slower than the temperature change rate of the real junction temperature of the IGBT chip, and there is a certain response delay. Therefore, the protection strategy of using the NTC temperature sensor to monitor the IGBT temperature has certain design defects, that is, under the condition of short-term stall and high torque, the temperature rise collected by the NTC has not risen to the protection threshold, but the real junction temperature of the IGBT chip has already exceeded the highest temperature threshold of the hardware, thereby causing the device to be damaged by overheating. In addition, the temperature protection strategy based on the NTC usually leaves a large temperature protection threshold, which greatly limits the junction temperature of the IGBT module, making the IGBT module far from reaching the maximum power output, resulting in the inability to fully release the power of the electric vehicle.

[0004] In the invention patent "Method, device and electronic device for estimating junction temperature of power device of motor controller" with application publication number CN117895872A, the network thermal resistance model is used to obtain the thermal impedance parameters, the conduction loss and switching loss of the power device in the switching cycle are calculated, and the integral loss of the power device is calculated. Finally, the junction temperature of the power device is obtained by the integral loss, thermal impedance parameters and the temperature acquisition value of the temperature sensor inside the power module. In this method, the conduction loss and switching loss of the power device are not determined from a microscopic level, and the loss of the metal bonding wire is not considered, resulting in the total loss of the power device in this method not being accurate enough, and the thermal impedance parameters of the upper bridge and the lower bridge are obtained as a whole, without considering the difference in junction temperature of the IGBT chip and the FRD diode, and the influence of other adjacent phase power devices on the temperature acquisition value of the temperature sensor, making the temperature acquisition value of the temperature sensor not accurate enough. Therefore, this method is more about estimating the junction temperature of the power device from a macroscopic level, and there are still great limitations on the output performance of the power device. Summary of the invention

[0005] In view of the above-mentioned problems, the present invention provides an estimation method for monitoring the junction temperature of an IGBT module, which monitors the precise junction temperature of the IGBT chip in real time at a microscopic level to ensure that the IGBT module can reach the maximum power as much as possible and fully release the power performance of the electric vehicle.

[0006] The technical solution of the present invention is: a method for estimating junction temperature monitoring of an IGBT module, comprising the following steps:

[0007] 1) Establish a third-order Foster thermal network model from the IGBT chip, FRD diode and NTC temperature sensor of the drive motor IGBT module to the coolant. According to the third-order Foster thermal network model from the IGBT chip, FRD diode and NTC temperature sensor to the coolant, obtain the third-order self-heating thermal resistance constant and the third-order heat transfer time constant of each IGBT chip and each FRD diode, the third-order mutual thermal resistance constant and the third-order heat transfer time constant between the IGBT chip and the FRD diode of the upper bridge and the lower bridge of each phase of the IGBT module, and the third-order mutual thermal resistance constant and the third-order heat transfer time constant between the NTC temperature sensor of each phase and the upper and lower bridge IGBT chips and FRD diodes of the same phase, and the upper bridge IGBT chip and the upper bridge FRD diode of the adjacent phase;

[0008] 2) Real-time acquisition of the phase voltage and phase current of each phase IGBT chip and FRD diode, and real-time acquisition of each phase junction temperature through the NTC temperature sensor;

[0009] 3) Determine the micro switch state of each IGBT chip and each FRD diode according to the value of the bottom PWM wave register, and obtain the PWM switching frequency and the duty cycle of each IGBT chip and FRD diode in a PWM cycle;

[0010] 4) According to the micro switch state of each IGBT chip and FRD diode, the phase voltage and phase current of each phase IGBT chip and FRD diode, calculate the turn-on loss, turn-off loss, conduction loss of each IGBT chip and the reverse recovery loss and conduction loss of the FRD diode; and according to the phase current of each phase IGBT chip and FRD diode, the duty cycle of each IGBT chip and FRD diode, calculate the metal bonding line loss of each IGBT chip and FRD diode;

[0011] 5) Calculate the total loss of each IGBT chip and FRD diode based on the turn-on loss, turn-off loss, conduction loss, metal bonding line loss of each IGBT chip and the reverse recovery loss, conduction loss, and metal bonding line loss of the FRD diode;

[0012] 6) According to the total loss of each IGBT chip and FRD diode, as well as the third-order self-heating thermal resistance constant and the third-order heat transfer time constant of each IGBT chip and each FRD diode obtained by the third-order Foster thermal network model in step 1), the third-order mutual thermal resistance constant and the third-order heat transfer time constant between the IGBT chips and FRD diodes of the upper bridge and the lower bridge of each phase of the IGBT module, respectively calculate the total temperature rise of each IGBT chip and FRD diode;

[0013] 7) According to the third-order Foster thermal network model obtained in step 1), the third-order mutual thermal resistance constant and the third-order heat transfer time constant between the NTC temperature sensors of each phase and the upper and lower bridge IGBT chips and FRD diodes of the same phase, and the upper bridge IGBT chips and upper bridge FRD diodes of adjacent phases are used to calculate the total temperature difference from the NTC temperature sensors of each phase to the coolant;

[0014] 8) Calculate the coolant temperature of each phase according to the total temperature difference from the NTC temperature sensor of each phase to the coolant and the junction temperature of each phase collected in real time by the NTC temperature sensor, and estimate the estimated junction temperature of each IGBT chip and each FRD diode according to the coolant temperature of each phase and the total temperature rise of each IGBT chip;

[0015] 9) Detect the real-time junction temperatures of each IGBT chip and each FRD diode through an infrared thermal imaging device and an IGBT black module controller observation system, and compare them with the estimated junction temperatures. If the estimated junction temperatures of each IGBT chip and each FRD diode are within the error range, then the estimated junction temperature is the final junction temperature of each IGBT chip and each FRD diode. If not, correct the turn-on loss, turn-off loss, conduction loss, and metal bonding wire loss of each IGBT and FRD, and then repeat steps 3 to 9) until the estimated junction temperatures of each IGBT chip and each FRD diode are within the error range.

[0016] Preferably, the following steps are further included.

[0017] 10) Establish an IGBT protection strategy. If the highest temperature among the final junction temperatures of each IGBT chip and each FRD diode is higher than the preset highest junction temperature of the IGBT protection strategy, trigger over-temperature protection. The motor controller starts linear torque limitation and maintains the torque reduction ratio until the highest temperature is lower than the preset lowest junction temperature threshold of the IGBT protection strategy, and then cancel the fault state to stop torque limitation to achieve chip over-temperature protection.

[0018] Preferably, in step 3), the values of the bottom-layer PWM wave generation register include the effective conduction time counter value D, the dead time register value DT, and the half-cycle counter value Prd. The microscopic switch states include five states: normally open, normally closed, turned on, turned off, and on-off.

[0019] Preferably, to determine that the microscopic switch state of the upper-bridge IGBT chip and the upper-bridge FRD diode is turned on, any one of the following three conditions needs to be satisfied:

[0020] ① D3 ≤ (Prd - DT) and D2 > (Prd - DT);

[0021] ② D2 ≥ DT and D2 ≤ (Prd - DT);

[0022] ③ D2 < DT and D1 ≥ DT;

[0023] To determine that the microscopic switch state of the upper-bridge IGBT chip and the upper-bridge FRD diode is turned off, any one of the following three conditions needs to be satisfied:

[0024] ① D1 ≥ DT and D1 ≤ Prd - DT);

[0025] ② D1 ≥ (Prd - DT) and D < (Prd - DT);

[0026] ③ D2 ≥ DT and D1 < DT;

[0027] To determine that the micro-switch state of the lower-bridge IGBT chip and the lower-bridge FRD diode is on, any one of the following three conditions must be satisfied:

[0028] ① D1 ≤ (Prd - DT) and D1 > DT;

[0029] ② D1 ≥ (Prd - DT) and D2 ≤ (Prd - DT);

[0030] ③ D1 < DT and D ≥ DT;

[0031] To determine that the micro-switch state of the lower-bridge IGBT chip and the lower-bridge FRD diode is off, any one of the following three conditions must be satisfied:

[0032] ① D2 ≥ DT and D2 ≤ (Prd - DT);

[0033] ② D1 < DT and D2 ≤ (Prd - DT);

[0034] ③ D2 < DT and D3 ≥ DT;

[0035] Wherein, D is the effective conduction time counter value, D1 is the value of the effective conduction time counter value D delayed by one PWM cycle, D2 is the value of the effective conduction time counter value D delayed by two PWM cycles, D3 is the value of the effective conduction time counter value D delayed by three PWM cycles, Prd is the half-cycle counter value, and DT is the dead-time register value;

[0036] If an IGBT chip or an FRD diode satisfies both the on state and the off state, its micro-switch state is the on-off state. If neither is satisfied, its micro-switch state is the normally open state or the normally closed state.

[0037] Preferably, in step 4), the calculation formula for the turn-on loss of the IGTB chip is:

[0038] E onigtb = E on * f * a * 0.001

[0039] Wherein, E onigtb is the turn-on loss of the IGTB chip, E on is the single turn-on loss of the IGTB chip, f is the PWM switching frequency, and a is the turn-on correction coefficient of the IGTB chip;

[0040] The calculation formula for the turn-off loss of the IGTB chip is:

[0041] E offigtb = E off * f * b * 0.001

[0042] Wherein, Eoffigtb is the turn-off loss of the IGBB chip, E off is the single turn-off loss of the IGTB chip, f is the PWM switching frequency, and b is the turn-off correction coefficient of the IGTB chip;

[0043] The calculation formula for the conduction loss of the IGTB chip is:

[0044]

[0045] Where P conigtb is the conduction loss of the IGBB chip, V ce0 is the cut-off voltage of the IGBT chip, R ce is the forward resistance of the IGBT chip, I cigtb is the phase current corresponding to each IGBT chip, D igtb The duty cycle corresponding to each IGBT chip;

[0046] The reverse recovery loss of the FRD diode is calculated as:

[0047] E recfrd =E rec *f*c*0.001

[0048] In the formula, E recfrd is the reverse recovery loss of the FRD diode, E rec is the reverse recovery loss of a single FRD diode, f is the PWM switching frequency, and c is the reverse recovery correction coefficient of the FRD diode;

[0049] The calculation formula for the conduction loss of FRD is:

[0050]

[0051] Where P confrd is the conduction loss of the FRD diode, V ce0 is the cut-off voltage of the FRD diode, R ce is the forward resistance of the FRD diode, I cfrd is the phase current corresponding to each FRD diode, D frd The duty cycle corresponding to each FRD diode.

[0052] Preferably, in step 4), the calculation formula for the metal bonding wire loss of the IGBT chip is:

[0053] E Bigtb =I cigtb *D igtb *X igtb

[0054] In the formula, E Bigtbis the metal bonding wire loss of the IGBT chip, I cigtb is the phase current corresponding to each IGBT chip, D igtb The duty cycle corresponding to each IGBT chip, X igtb It is the metal bonding wire correction factor of IGBT chip;

[0055] The calculation formula for the metal bonding line loss of the FRD diode is:

[0056] E Bfrd =I cfrd *D frd *X frd

[0057] In the formula, E Bfrd is the metal bonding line loss of the FRD diode, I cfrd is the phase current corresponding to each FRD diode, D frd The duty cycle of each FRD diode, X frd is the metal bond wire correction factor for FRD diodes.

[0058] The advantages of the present invention are as follows: the present invention first determines the microscopic switching state of each IGBT chip and each FRD diode, and calculates the turn-on loss, turn-off loss, conduction loss of each IGBT chip and the reverse recovery loss and conduction loss of each FRD diode according to the phase current and the phase voltage, and then calculates the metal bonding line loss of each IGBT chip and each FRD diode, thereby determining the total loss of each IGBT chip and each FRD diode; by determining the microscopic switching state of each IGBT chip and each FRD diode, the turn-on loss, turn-off loss, conduction loss of each IGBT chip and the reverse recovery loss and conduction loss of each FRD diode can be more accurately calculated; adding the calculation of the metal bonding line loss can more accurately reflect the total loss of each IGBT chip and each FRD diode, thereby making the estimated temperature rise of each IGBT chip and each FRD diode more practical, while ensuring that the IGBT module can reach the maximum power as much as possible and fully release the power performance of the electric vehicle, ensuring that a more accurate and effective IGBT protection strategy can be established to prevent the IGBT module from overheating and burning. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0060] See also Figure 1 , an estimation method for monitoring junction temperature of an IGBT module, comprising the following steps:

[0061] 1) Establish a third-order Foster thermal network model for the IGBT chip, FRD diode, and NTC temperature sensor of the drive motor IGBT module to the coolant. Obtain the third-order self-thermal resistance constants and third-order heat transfer time constants of each IGBT chip and each FRD diode from the third-order Foster thermal network model of the IGBT chip, FRD diode, and NTC temperature sensor to the coolant, the third-order mutual thermal resistance constants and third-order heat transfer time constants between the IGBT chips and FRD diodes of the upper and lower bridges of each phase of the IGBT module, and the third-order mutual thermal resistance constants and third-order heat transfer time constants between each phase NTC temperature sensor and the upper and lower bridge IGBT chips, FRD diodes of the same phase, and the upper bridge IGBT chips and upper bridge FRD diodes of the adjacent phase;

[0062] 2) Real-time collect the phase voltages and phase currents of the IGBT chips and FRD diodes of each phase, and real-time collect the junction temperatures of each phase through the NTC temperature sensor;

[0063] 3) Judge the microscopic switching states of each IGBT chip and each FRD diode according to the values of the underlying PWM wave generation register, and obtain the PWM switching frequency and the duty cycle of each IGBT chip and FRD diode within one PWM cycle;

[0064] The values of the underlying PWM wave generation register include the effective conduction time counter value D, the dead time register value DT, and the half-cycle counter value Prd. The microscopic switching states include five states:常开 (normally open),常闭 (normally closed),开通 (turned on),断开 (turned off),通断 (on and off).

[0065] Judging that the microscopic switching states of the upper bridge IGBT chip and the upper bridge FRD diode are turned on requires satisfying any one of the following three conditions:

[0066] ① D3 ≤ (Prd - DT) and D2 > (Prd - DT);

[0067] ② D2 ≥ DT and D2 ≤ (Prd - DT);

[0068] ③ D2 < DT and D1 ≥ DT;

[0069] Judging that the microscopic switching states of the upper bridge IGBT chip and the upper bridge FRD diode are turned off requires satisfying any one of the following three conditions:

[0070] ① D1 ≥ DT and D1 ≤ Prd - DT);

[0071] ② D1 ≥ (Prd - DT) and D < (Prd - DT);

[0072] ③ D2 ≥ DT and D1 < DT;

[0073] To determine that the micro-switch states of the lower-bridge IGBT chip and the lower-bridge FRD diode are on, any one of the following three conditions must be met:

[0074] ① D1 ≤ (Prd - DT) and D1 > DT;

[0075] ② D1 ≥ (Prd - DT) and D2 ≤ (Prd - DT);

[0076] ③ D1 < DT and D ≥ DT;

[0077] To determine that the micro-switch states of the lower-bridge IGBT chip and the lower-bridge FRD diode are off, any one of the following three conditions must be met:

[0078] ① D2 ≥ DT and D2 ≤ (Prd - DT);

[0079] ② D1 < DT and D2 ≤ (Prd - DT);

[0080] ③ D2 < DT and D3 ≥ DT;

[0081] Where D is the value of the effective conduction time counter, D1 is the value of the effective conduction time counter D delayed by one PWM cycle, D2 is the value of the effective conduction time counter D delayed by two PWM cycles, D3 is the value of the effective conduction time counter D delayed by three PWM cycles, Prd is the value of the half-cycle counter, and DT is the value of the dead-time register;

[0082] If an IGBT chip or an FRD diode satisfies both the on state and the off state, its micro-switch state is in the on-off state. If neither is satisfied, its micro-switch state is in the normally open state or the normally closed state.

[0083] 4) Calculate the turn-on loss, turn-off loss, conduction loss of each IGBT chip and the reverse recovery loss and conduction loss of the FRD diode according to the micro-switch states of each IGBT chip and FRD diode, the phase voltages and phase currents of each phase of the IGBT chip and FRD diode; and calculate the metal bonding wire loss of each IGBT chip and FRD diode according to the phase currents of each phase of the IGBT chip and FRD diode and the duty cycles of each IGBT chip and FRD diode;

[0084] The calculation formula for the turn-on loss of the IGTB chip is:

[0085] E onigtb =E on *f*a*0.001

[0086] Where E onigtb is the turn-on loss of the IGTB chip, E onis the single turn-on loss of the IGTB chip, f is the PWM switching frequency, and a is the turn-on correction coefficient of the IGTB chip;

[0087] The calculation formula for the turn-off loss of the IGTB chip is:

[0088] E offigtb =E off *f*b*0.001

[0089] In the formula, E offigtb is the turn-off loss of the IGBB chip, E off is the single turn-off loss of the IGTB chip, f is the PWM switching frequency, and b is the turn-off correction coefficient of the IGTB chip;

[0090] The calculation formula for the conduction loss of the IGTB chip is:

[0091]

[0092] Where P conigtb is the conduction loss of the IGBB chip, V ce0 is the cut-off voltage of the IGBT chip, R ce is the forward resistance of the IGBT chip, I cigtb is the phase current corresponding to each IGBT chip, D igtb The duty cycle corresponding to each IGBT chip;

[0093] The reverse recovery loss of the FRD diode is calculated as:

[0094] E recfrd =E rec *f*c*0.001

[0095] In the formula, E recfrd is the reverse recovery loss of the FRD diode, E rec is the reverse recovery loss of a single FRD diode, f is the PWM switching frequency, and c is the reverse recovery correction coefficient of the FRD diode;

[0096] The calculation formula for the conduction loss of FRD is:

[0097]

[0098] Where P confrd is the conduction loss of the FRD diode, V ce0 is the cut-off voltage of the FRD diode, R ce is the forward resistance of the FRD diode, I cfrd is the phase current corresponding to each FRD diode, D frd The duty cycle corresponding to each FRD diode.

[0099] The calculation formula for the metal bonding wire loss of the IGBT chip is:

[0100] E Bigtb =I cigtb *D igtb *X igtb

[0101] In the formula, E Bigtb is the metal bonding wire loss of the IGBT chip, I cigtb is the phase current corresponding to each IGBT chip, D igtb The duty cycle corresponding to each IGBT chip, X igtb It is the metal bonding wire correction factor of IGBT chip;

[0102] The calculation formula for the metal bonding line loss of the FRD diode is:

[0103] E Bfrd =I cfrd *D frd *X frd

[0104] In the formula, E Bfrd is the metal bonding line loss of the FRD diode, I cfrd is the phase current corresponding to each FRD diode, D frd The duty cycle of each FRD diode, X frd is the metal bond wire correction factor for FRD diodes.

[0105] 5) Calculate the total loss of each IGBT chip and FRD diode based on the turn-on loss, turn-off loss, conduction loss, metal bonding line loss of each IGBT chip and the reverse recovery loss, conduction loss, and metal bonding line loss of the FRD diode;

[0106] The total loss of each IGBT chip is:

[0107] P igtb =E onigtb +E offigtb +P conigtb +E Bigtb

[0108] Where P igtb is the total loss of the IGBT chip, E onigtb is the turn-on loss of the IGBB chip, E offigtb is the turn-off loss of the IGBB chip, P conigtb is the conduction loss of the IGBB chip, E Bigtb is the metal bonding wire loss of the IGBT chip.

[0109] The total loss of each FRD diode is:

[0110] P frd =E recfrd +P confrd +E Bfrd

[0111] Where P frd is the total loss of the FRD diode, E recfrd is the reverse recovery loss of the FRD diode, P confrd is the conduction loss of the FRD diode, E Bigtb is the metal bonding wire loss of the IGBT chip.

[0112] 6) According to the total loss of each IGBT chip and FRD diode, as well as the third-order self-heating thermal resistance constant and the third-order heat transfer time constant of each IGBT chip and each FRD diode obtained by the third-order Foster thermal network model in step 1), the third-order mutual thermal resistance constant and the third-order heat transfer time constant between the IGBT chips and FRD diodes of the upper bridge and lower bridge of each phase of the IGBT module, the total temperature rise of each IGBT chip and FRD diode is calculated respectively; in calculating the total temperature rise of each IGBT chip and FRD diode, it is necessary to consider the self-heating temperature rise and the mutual heating temperature rise caused by other ICBT chips and FRD diodes of the same phase, so as to determine the total temperature rise. In this embodiment, taking the calculation of the U-phase upper bridge IGBT as an example, the formula for calculating the total temperature rise of the U-phase upper bridge IGBT is as follows:

[0113]

[0114]

[0115] Where, △T UHigtb is the total temperature rise of the U-phase upper bridge IGBT chip, P UHigtb is the total loss of the U-phase upper bridge IGBT chip, R UHigtb1 , R UHigtb2 , R UHigtb3 are the third-order self-heating thermal resistance constant of the U-phase upper bridge IGTB chip as a heat source, τ UHigtb1 , τ UHigtb2 , τ UHigtb3 are the third-order heat transfer time constant of the U-phase upper bridge IGTB chip as the heat source, P UHfrd is the total loss of the U-phase upper bridge FRD diode, R UHfrd-Higtb1 , R UHfrd-Higtb2 , R UHfrd-Higtb3 are the third-order mutual thermal resistance constant of the U-phase upper bridge FRD diode as a heat source to the U-phase upper bridge IGTB chip, τ UHfrd-Higtb1 , τ UHfrd-Higtb2 , τ UHfrd-Higtb3are the third-order heat transfer time constant of the U-phase upper bridge FRD diode as a heat source to the U-phase upper bridge IGTB chip, P ULigtb is the total loss of the U-phase lower bridge IGBT chip, R ULigtb-Higtb1 , R ULigtb-Higtb2 , R ULigtb-Higtb3 are the third-order mutual thermal resistance constant of the U-phase lower bridge IGTB chip as a heat source to the U-phase upper bridge IGTB chip, τ ULigtb-Higtb1 , τ ULigtb-Higtb2 , τ ULigtb-Higtb3 are the third-order heat transfer time constant of the U-phase lower bridge IGTB chip as the heat source to the U-phase upper bridge IGTB chip, P ULfrd is the total loss of the U-phase lower bridge FRD diode, R ULfrd-Higtb1 , R ULfrd-Higtb2 , R ULfrd-Higtb3 are the third-order mutual thermal resistance constant of the U-phase lower bridge FRD diode as a heat source to the U-phase upper bridge IGTB chip, τ ULfrd-Higtb1 , τ ULfrd-Higtb2 , τ ULfrd-Higtb3 are the third-order heat transfer time constants of the U-phase lower bridge FRD diode as a heat source to the U-phase upper bridge IGTB chip, and s is the sampling time.

[0116] The calculation method for the remaining IGBT chips and FRD diodes is similar to that for the U-phase upper bridge IGBT chip.

[0117] 7) According to the third-order Foster thermal network model of step 1), the third-order mutual thermal resistance constant and the third-order heat transfer time constant between the NTC temperature sensors of each phase and the upper and lower bridge IGBT chips and FRD diodes of the same phase, and the upper bridge IGBT chips and upper bridge FRD diodes of the adjacent phases are respectively calculated, and the total temperature difference from the NTC temperature sensors of each phase to the coolant is respectively calculated; since the NTC temperature sensor is installed between the upper bridges of the two phases, and the NTC temperature sensor itself does not generate heat, that is, the NTC temperature sensor has no self-heating, the NTC temperature sensor will only be affected by the mutual heat brought by the upper and lower bridge IGBT chips and FRD diodes of the same phase and the upper bridge IGBT chips and FRD diodes of the adjacent phases. It should be particularly noted that in the present invention, the U-phase NTC temperature sensor is arranged next to the U-phase, and the adjacent phase is only the U-phase, so it is only affected by the mutual heat brought by the upper and lower bridge IGBT chips and FRD diodes of the same phase. In this embodiment, taking the calculation of the total temperature difference from the V-phase NTC temperature sensor to the coolant as an example, the V-phase NTC temperature sensor is installed between the V-phase upper bridge and the U-phase upper bridge, and the calculation formula is:

[0118]

[0119]

[0120] Where, △T Vntc is the total temperature difference from the V-phase NTC temperature sensor to the coolant, P VHigtb is the total loss of the V-phase upper bridge IGBT chip, R VHigtb-Vntc1 , R VHigtb-Vntc2 , R VHigtb-Vntc3 are the third-order mutual thermal resistance constant of the V-phase upper bridge IGTB chip as a heat source to the V-phase NTC temperature sensor, τ VHigtb-Vntc1 , τ VHigtb-Vntc2 , τ VHigtb-Vntc3 are the third-order heat transfer time constant of the V-phase upper bridge IGBB chip as a heat source to the V-phase NTC temperature sensor, P VHfrd is the total loss of the V-phase upper bridge FRD diode, R VHfrd-Vntc1 , R VHfrd-Vntc2 , R VHfrd-Vntc3 are the third-order mutual thermal resistance constant of the V-phase upper bridge FRD diode as a heat source to the V-phase NTC temperature sensor, τ VHfrd-Vntc1 , τ VHfrd-Vntc2 , τ VHfrd-Vntc3 are the third-order heat transfer time constant of the V-phase upper bridge FRD diode as a heat source to the V-phase NTC temperature sensor, P VLigtb is the total loss of the V-phase lower bridge IGBT chip, R VLigtb-Vntc1 , R VLigtb-Vntc2 , R VLigtb-Vntc3 are the third-order mutual thermal resistance constant of the V-phase lower bridge IGTB chip as a heat source to the V-phase NTC temperature sensor, τ VLigtb-Vntc1 , τ VLigtb-Vntc2 , τ VLigtb-Vntc3 are the third-order heat transfer time constant of the V-phase lower bridge IGTB chip as a heat source to the V-phase NTC temperature sensor, P VLfrd is the total loss of the V-phase lower bridge FRD diode, R VLfrd-Vntc1 , R VLfrd-Vntc2 , R VLfrd-Vntc3 are the third-order mutual thermal resistance constant of the V-phase lower bridge FRD diode as a heat source to the V-phase NTC temperature sensor, τ VLfrd-Vntc1 , τ VLfrd-Vntc2 , τ VLfrd-Vntc3 are the third-order heat transfer time constant of the V-phase lower bridge FRD diode as a heat source to the V-phase NTC temperature sensor, P UHigtb is the total loss of the U-phase upper bridge IGBT chip, R UHigtb-Vntc1 , R UHigtb-Vntc2 , R UHigtb-Vntc3 are the third-order mutual thermal resistance constant of the U-phase upper bridge IGTB chip as a heat source to the V-phase NTC temperature sensor, τ UHigtb-Vntc1 , τ UUHigtb-Vntc2 , τ UHigtb-Vntc3are the third-order heat transfer time constant of the U-phase upper bridge IGTB chip as a heat source to the V-phase NTC temperature sensor, P ULigtb is the total loss of the U-phase lower bridge IGBT chip, R UHfrd-Higtb1 , R UHfrd-Higtb2 , R UHfrd-Higtb3 are the third-order mutual thermal resistance constant of the U-phase upper bridge FRD diode as a heat source to the V-phase NTC temperature sensor, τ UHfrd-Higtb1 , τ UHfrd-Higtb2 , τ UHfrd-Higtb3 They are the third-order heat transfer time constants of the U-phase upper bridge FRD diode as a heat source to the V-phase NTC temperature sensor.

[0121] Similarly, the total temperature difference between the U-phase NTC temperature sensor and the W-phase NTC temperature sensor and the coolant is calculated.

[0122] 8) According to the total temperature difference between each phase NTC temperature sensor and the coolant and the junction temperature of each phase collected in real time by the NTC temperature sensor, the coolant temperature of each phase is calculated, and according to the coolant temperature of each phase and the total temperature rise of each IGBT chip, the estimated junction temperature of each IGBT chip and each FRD diode is estimated; in this embodiment, taking the calculation of the V phase coolant temperature as an example, the V phase coolant temperature is:

[0123] T Vcool =T Vntc -△T Vntc

[0124] Where, T Vcool is the V-phase coolant temperature, T Vntc is the junction temperature collected in real time by the V-phase NTC temperature sensor, △T Vntc It is the total temperature difference from the V-phase NTC temperature sensor to the coolant.

[0125] Similarly, the U-phase coolant temperature and the W-phase coolant temperature can be calculated.

[0126] The estimated junction temperature of the V-phase upper bridge IGBT chip is estimated based on the V-phase coolant temperature:

[0127] T VHigbt =△T VHigtb +T Vcool

[0128] Where, T VHigbt is the estimated junction temperature of the V-phase upper bridge IGBT chip, △T VHigtb is the total temperature rise of the V-phase upper bridge IGBT chip, T Vcool is the V-phase coolant temperature.

[0129] Similarly, the estimated junction temperature of each IGBT chip and each FRD diode is calculated.

[0130] 9) Detect the real-time junction temperatures of each IGBT chip and each FRD diode through an infrared thermal imaging device and an IGBT black module controller observation system, and compare them with the estimated junction temperatures. If the estimated junction temperatures of each IGBT chip and each FRD diode are within the error range, then the estimated junction temperature is the final junction temperature of each IGBT chip and each FRD diode. If not, correct the correction factors for the turn-on loss, turn-off loss, conduction loss, and metal bonding wire loss of each IGBT and FRD, and then repeat steps 3 to 9) until the estimated junction temperatures of each IGBT chip and each FRD diode are within the error range.

[0131] 10) Establish an IGBT protection strategy. If the highest temperature among the final junction temperatures of each IGBT chip and each FRD diode is higher than the preset highest junction temperature threshold of the IGBT protection strategy, trigger over-temperature protection. The motor controller starts to linearly limit the torque, maintains the torque reduction ratio until the highest temperature is lower than the preset lowest junction temperature threshold of the IGBT protection strategy, and then cancels the fault state to stop limiting the torque to achieve chip over-temperature protection. The preset highest junction temperature T of the IGBT protection strategy is set according to the highest junction temperature T1 of the external characteristic working condition tested in the bench test and the highest short-time tolerable temperature T2 given by the module manufacturer. The preset highest junction temperature T of the IGBT protection strategy satisfies T1 < T < T2, ensuring that the junction temperature protection does not affect the external characteristic output and can effectively achieve chip over-temperature protection. The preset lowest junction temperature threshold of the IGBT protection strategy is determined according to the usually safe operating temperature of the chip. In addition, since the IGBT protection strategy established in the present invention is based on the NTC temperature protection strategy of the IGBT module itself, the junction temperature protection threshold of the IGBT protection strategy established in the present invention should be higher than the junction temperature corresponding to the protection strategy threshold of the NTC temperature, forming a dual temperature protection to make up for the protection defect caused by the slow response of the NTC. The lowest junction temperature threshold is set to avoid repeated triggering of faults and affect the driving performance, and ensure that normal control can be restored after cooling. Therefore, its value is usually set at a conventional safe operating temperature such as 120°C.

[0132] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Without departing from the spirit of the present invention, any modifications made by those skilled in the art fall within the protection scope of the present invention.

Claims

1. An estimation method for IGBT module junction temperature monitoring, It is characterized in that The following steps are involved: 1) Establish a third-order Foster thermal network model from the IGBT chip, FRD diode and NTC temperature sensor of the drive motor IGBT module to the coolant. According to the third-order Foster thermal network model from the IGBT chip, FRD diode and NTC temperature sensor to the coolant, obtain the third-order self-heating thermal resistance constant and the third-order heat transfer time constant of each IGBT chip and each FRD diode, the third-order mutual thermal resistance constant and the third-order heat transfer time constant between the IGBT chip and the FRD diode of the upper bridge and the lower bridge of each phase of the IGBT module, and the third-order mutual thermal resistance constant and the third-order heat transfer time constant between the NTC temperature sensor of each phase and the upper and lower bridge IGBT chips and FRD diodes of the same phase, and the upper bridge IGBT chip and the upper bridge FRD diode of the adjacent phase; 2) Real-time acquisition of the phase voltage and phase current of each phase IGBT chip and FRD diode, and real-time acquisition of each phase junction temperature through the NTC temperature sensor; 3) Determine the micro switch state of each IGBT chip and each FRD diode according to the value of the bottom PWM wave register, and obtain the PWM switching frequency and the duty cycle of each IGBT chip and FRD diode in a PWM cycle; 4) According to the micro switch state of each IGBT chip and FRD diode, the phase voltage and phase current of each phase IGBT chip and FRD diode, calculate the turn-on loss, turn-off loss, conduction loss of each IGBT chip and the reverse recovery loss and conduction loss of the FRD diode; and according to the phase current of each phase IGBT chip and FRD diode, the duty cycle of each IGBT chip and FRD diode, calculate the metal bonding line loss of each IGBT chip and FRD diode; 5) Calculate the total loss of each IGBT chip and FRD diode based on the turn-on loss, turn-off loss, conduction loss, metal bonding line loss of each IGBT chip and the reverse recovery loss, conduction loss, and metal bonding line loss of the FRD diode; 6) According to the total loss of each IGBT chip and FRD diode, as well as the third-order self-heating thermal resistance constant and the third-order heat transfer time constant of each IGBT chip and each FRD diode obtained by the third-order Foster thermal network model in step 1), the third-order mutual thermal resistance constant and the third-order heat transfer time constant between the IGBT chips and FRD diodes of the upper bridge and the lower bridge of each phase of the IGBT module, respectively calculate the total temperature rise of each IGBT chip and FRD diode; 7) According to the third-order Foster thermal network model obtained in step 1), the third-order mutual thermal resistance constant and the third-order heat transfer time constant between the NTC temperature sensors of each phase and the upper and lower bridge IGBT chips and FRD diodes of the same phase, and the upper bridge IGBT chips and upper bridge FRD diodes of adjacent phases are used to calculate the total temperature difference from the NTC temperature sensors of each phase to the coolant; 8) Calculate the coolant temperature of each phase based on the total temperature difference between each phase NTC temperature sensor and the coolant and the junction temperature of each phase collected in real time by the NTC temperature sensor, and estimate the estimated junction temperature of each IGBT chip and each FRD diode based on the coolant temperature of each phase and the total temperature rise of each IGBT chip; 9) Detect the real-time junction temperature of each IGBT chip and each FRD diode through an infrared thermal imaging device and an IGBT black module controller observation system, and compare it with the estimated junction temperature. If the estimated junction temperature of each IGBT chip and each FRD diode is within the error range, then the estimated junction temperature is the final junction temperature of each IGBT chip and each FRD diode. If it is not within the error range, correct the turn-on loss, turn-off loss, conduction loss, and metal bonding wire loss of each IGBT and FRD, and then repeat steps 3 to 9) until the estimated junction temperature of each IGBT chip and each FRD diode is within the error range.

2. An estimation method for IGBT module junction temperature monitoring according to claim 1, characterized in that: It further includes the following steps, 10) Establish an IGBT protection strategy. If the highest temperature among the final junction temperatures of each IGBT chip and each FRD diode is higher than the highest junction temperature preset by the IGBT protection strategy, trigger over-temperature protection, and the motor controller starts to linearly limit torque, maintaining the torque reduction ratio until the highest temperature is lower than the lowest junction temperature threshold preset by the IGBT protection strategy, and then cancel the fault state to stop limiting torque to achieve chip over-temperature protection.

3. An estimation method for IGBT module junction temperature monitoring according to claim 1, characterized in that: In step 3), the values of the bottom-layer PWM wave generation register include the effective conduction time counter value D, the dead-time register value DT, and the half-cycle counter value Prd, and the microscopic switch states include five states: normally open, normally closed, turned on, turned off, and on-off.

4. An estimation method for IGBT module junction temperature monitoring according to claim 3, characterized in that: To determine that the microscopic switch state of the upper-bridge IGBT chip and the upper-bridge FRD diode is turned on, any one of the following three conditions needs to be met: ① D3 ≤ (Prd - DT) and D2 > (Prd - DT); ② D2 ≥ DT and D2 ≤ (Prd - DT); ③ D2 < DT and D1 ≥ DT; To determine that the microscopic switch state of the upper-bridge IGBT chip and the upper-bridge FRD diode is turned off, any one of the following three conditions needs to be met: ① D1 ≥ DT and D1 ≤ Prd - DT); ② D1 ≥ (Prd - DT) and D < (Prd - DT); ③ D2 ≥ DT and D1 < DT; To determine that the microscopic switch state of the lower-bridge IGBT chip and the lower-bridge FRD diode is turned on, any one of the following three conditions needs to be met: ① D1 ≤ (Prd - DT) and D1 > DT; ② D1 ≥ (Prd - DT) and D2 ≤ (Prd - DT); ③ D1 < DT and D ≥ DT; To determine that the microscopic switch state of the lower-bridge IGBT chip and the lower-bridge FRD diode is turned off, any one of the following three conditions needs to be met: ①D2 ≥ DT and D2 ≤ (Prd - DT); ②D1 < DT and D2 ≤ (Prd - DT); ③D2 < DT and D3 ≥ DT; Wherein, D is the value of the effective conduction time counter, D1 is the value of the effective conduction time counter D delayed by one PWM cycle, D2 is the value of the effective conduction time counter D delayed by two PWM cycles, D3 is the value of the effective conduction time counter D delayed by three PWM cycles, Prd is the value of the half-cycle counter, and DT is the value of the dead-time register; If a certain IGBT chip or FRD diode satisfies both the on-state and the off-state, its microscopic switching state is the on-off state. If neither is satisfied, its microscopic switching state is the normally open state or the normally closed state.

5. An estimation method for IGBT module junction temperature monitoring according to claim 1, characterized in that: In the step 4), the calculation formula for the turn-on loss of the IGTB chip is: HAVE BEEN onigtb =E on *f*a*0.001 In the formula, E onigtb is the turn-on loss of the IGBB chip, E on is the single turn-on loss of the IGTB chip, f is the PWM switching frequency, and a is the turn-on correction coefficient of the IGTB chip; The calculation formula for the turn-off loss of the IGTB chip is: E offigtb =E off *f*b*0.001 In the formula, E offigtb is the turn-off loss of the IGBB chip, E off is the single turn-off loss of the IGTB chip, f is the PWM switching frequency, and b is the turn-off correction coefficient of the IGTB chip; The calculation formula for the conduction loss of the IGTB chip is: Where P conigtb is the conduction loss of the IGBB chip, V ce0 is the cut-off voltage of the IGBT chip, R ce is the forward resistance of the IGBT chip, I cigtb is the phase current corresponding to each IGBT chip, D igtb The duty cycle corresponding to each IGBT chip; The calculation formula for the reverse recovery loss of the FRD diode is: E recfrd =E rec *f*c*0.001 In the formula, E recfrd is the reverse recovery loss of the FRD diode, E rec is the reverse recovery loss of a single FRD diode, f is the PWM switching frequency, and c is the reverse recovery correction coefficient of the FRD diode; The calculation formula for the conduction loss of the FRD is: Where P confrd is the conduction loss of the FRD diode, V ce0 is the cut-off voltage of the FRD diode, R ce is the forward resistance of the FRD diode, I cfrd is the phase current corresponding to each FRD diode, D frd The duty cycle corresponding to each FRD diode.

6. An estimation method for IGBT module junction temperature monitoring according to claim 1, characterized in that: In the step 4), the calculation formula for the metal bonding wire loss of the IGBT chip is: E Bigtb =I cigtb *D igtb *X igtb In the formula, E Bigtb is the metal bonding wire loss of the IGBT chip, I cigtb is the phase current corresponding to each IGBT chip, D igtb The duty cycle corresponding to each IGBT chip, X igtb It is the metal bonding wire correction factor of IGBT chip; The calculation formula for the metal bonding wire loss of the FRD diode is: E Bfrd =I cfrd *D frd *X frd In the formula, E Bfrd is the metal bonding line loss of the FRD diode, I cfrd is the phase current corresponding to each FRD diode, D frd The duty cycle corresponding to each FRD diode, X frd is the metal bond wire correction factor for FRD diodes.

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