Power module junction temperature estimation method and device, module, motor controller and vehicle

Abstract

The present application relates to a kind of power module junction temperature estimation method, device, module, motor controller and vehicle, comprising: real-time acquisition power module three-phase bridge arm respective operating parameter, for each phase synchronous using thermal network method, large current saturation voltage drop method respectively estimates the initial junction temperature of corresponding power device;According to the real-time operating parameter of power module, identify the current working condition is steady state or transient state;According to the working condition type identified, using different correction strategies, the initial junction temperature of each phase output by thermal network method is compensated and corrected, and the final junction temperature of each phase power device is obtained;Extract the final junction temperature corresponding to all power devices of three-phase bridge arm, select the maximum value as the system output junction temperature.The present application can improve the control accuracy of system under the influence of uncertain factors.The present application can improve the accuracy of junction temperature estimation, and can cover the failure caused by solder layer and bonding wire.

Description

Technical Field

[0001] This invention relates to the field of power module technology, specifically to a method, apparatus, module, motor controller, and vehicle for estimating the junction temperature of a power module. Background Technology

[0002] With the rapid development of electric vehicles, it is crucial not only to ensure the normal operation of IGBTs throughout the entire system lifecycle but also to maintain high reliability of IGBT power modules during operation. The highest temperature of an IGBT chip is called its junction temperature; excessively high junction temperatures can damage the silicon chip. Due to the characteristics of semiconductor materials and limitations in the manufacturing process, the maximum safe temperature of an IGBT chip typically cannot exceed 175°C. Failures of power semiconductor devices like IGBTs are often closely related to excessively high temperatures and frequent thermal cycling. Therefore, accurate junction temperature estimation is key to preventing power module failures and predicting lifespan. While traditional loss-based junction temperature estimation methods offer high real-time performance, their accuracy decreases with module aging and they cannot handle solder layer failures. Summary of the Invention

[0003] The purpose of this invention is to provide a method, device, module, motor controller, and vehicle for estimating junction temperature of a power module, which can improve the accuracy of junction temperature estimation and cover failures caused by solder layers and bonding wires.

[0004] In a first aspect, the power module junction temperature estimation method of the present invention includes the following steps:

[0005] Real-time acquisition of the operating parameters of each of the three-phase bridge arms of the power module; and estimation of the initial junction temperature of the corresponding power device for each phase using the thermal network method and the high current saturation voltage drop method.

[0006] Based on the real-time operating parameters of the power module, the current operating condition can be identified as either steady-state or transient.

[0007] Based on the identified operating condition type, a differentiated correction strategy is adopted to compensate and correct the initial junction temperature of each phase output by the thermal network method, thereby obtaining the final junction temperature of each phase power device.

[0008] The differentiated correction strategy includes a steady-state correction strategy and a transient correction strategy:

[0009] The steady-state correction strategy is as follows: the temperature difference between the single-phase junction temperature output by the high-current saturation voltage drop method and the single-phase initial junction temperature output by the thermal network method is used as the correction benchmark to compensate and correct the thermal resistance loss term in the thermal network method.

[0010] The transient correction strategy is as follows: using the temperature difference between the single-phase junction temperature output by the high-current saturation voltage drop method and the single-phase initial junction temperature output by the thermal network method as the correction benchmark, the NTC sampling temperature involved in the calculation in the thermal network method is compensated and corrected.

[0011] This invention constructs a comprehensive junction temperature estimation system integrating the thermal network method and the high-current saturation voltage drop method, effectively overcoming the technical shortcomings of traditional single junction temperature estimation algorithms, such as limited application scenarios and insufficient accuracy across all operating conditions. This solution simultaneously collects the operating parameters of the three-phase bridge arms of the power module, using dual algorithms in parallel to estimate the initial junction temperature of the devices. It fully combines the technical advantages of both algorithms to compensate for their respective performance deficiencies. Furthermore, it accurately distinguishes between steady-state and transient core operating conditions based on the equipment's operating parameters, and designs differentiated, dedicated correction strategies based on the temperature response characteristics of different operating conditions to specifically address estimation errors under different conditions. Specifically, it fully utilizes the high estimation accuracy of the high-current saturation voltage drop method near the rated current to meet the correction requirements of steady-state operating conditions. Simultaneously, leveraging the decoupling and hysteresis-free advantages of this algorithm with the NTC temperature sensor, it meets the temperature correction requirements of transient operating conditions. It precisely compensates and corrects the thermal resistance parameters of the thermal network method and the NTC sampling temperature, completely solving the problems of poor operating condition adaptability and surging errors during operating condition switching inherent in traditional methods. Ultimately, by selecting the maximum junction temperature of the three-phase devices as the output result, the high-temperature failure risk point of the module is accurately located, which comprehensively improves the accuracy and reliability of junction temperature estimation under all operating conditions of the power module, and provides reliable technical support for the accurate over-temperature protection and long-term life assessment of the power module.

[0012] Optionally, the determination criteria for the steady-state operating condition are:

[0013] The effective value of any phase current of the power module is in the range of 0.8 to 1.2 times the rated current, the effective value change rate of the phase current is less than the first preset threshold, and the motor speed is in the range of 1000 to 3000 rpm.

[0014] The steady-state correction strategy is as follows:

[0015] The temperature difference between the single-phase junction temperature calculated by the high-current saturation voltage drop method and the single-phase initial junction temperature calculated by the thermal network method under steady-state conditions is calculated. ;

[0016] Based on the temperature difference Constructing thermal resistance loss compensation terms , To match the temperature difference The obtained thermal resistance correction coefficient is dynamically updated as the power module ages.

[0017] The thermal resistance loss compensation term is superimposed onto the original calculation formula of the thermal network. Using the corrected formula The final temperature of the corresponding phase is obtained.

[0018] This invention clarifies the precise judgment threshold and exclusive correction logic for steady-state operating conditions. By limiting the steady-state judgment conditions to the rated current range, current change rate, and motor speed, it can accurately screen out steady-state operating scenarios with stable power module operation and small parameter fluctuations, avoiding correction failures caused by misjudgment of operating conditions. At the same time, it innovatively adopts a thermal resistance loss compensation method based on dual-algorithm junction temperature difference, introducing a thermal resistance correction coefficient that is dynamically updated with the aging time of the module. This can adapt in real time to the characteristics of thermal resistance aging and heat dissipation performance degradation during long-term operation of the power module, effectively making up for the shortcomings of the traditional thermal network method, which has fixed thermal resistance parameters and cannot adapt to device aging, and has large deviations in loss calculation under steady-state conditions. The junction temperature can be accurately corrected under steady-state operating conditions through a simple and efficient superposition correction formula, which significantly improves the accuracy of junction temperature estimation during long-term steady-state operation of the power module, solves the problem of accumulated deviations in steady-state junction temperature estimation after device aging, and ensures the reliability of temperature monitoring during long-term steady-state operation of the equipment.

[0019] Optionally, the determination criterion for the transient operating condition is to satisfy any of the following conditions:

[0020] The actual torque change rate of the motor is greater than 5000 Nm / s, the speed change rate is greater than 80 r / s², and the effective value change rate of the phase current is greater than 50 Arms / s;

[0021] The transient correction strategy is as follows: under transient operating conditions, calculate the difference in junction temperature between the high-current saturation voltage drop method and the thermal network method. ,

[0022] Based on the temperature difference Constructing NTC temperature compensation terms , To match the temperature difference The obtained NTC temperature correction factor;

[0023] The NTC temperature compensation term is superimposed onto the original calculation formula of the thermal network. Using the corrected formula The final temperature of the corresponding phase is obtained.

[0024] This invention refines the quantitative judgment criteria and exclusive correction strategies for transient operating conditions. By setting thresholds for the rate of change of torque, speed, and phase current, it can quickly and accurately identify various transient impact conditions such as sudden load changes, speed fluctuations, and sudden current changes in power modules, covering the core abnormal scenarios of dynamic equipment operation. Addressing the industry pain point of delayed NTC temperature sampling and inability to quickly respond to sudden temperature changes in devices under transient conditions, this invention abandons the steady-state thermal resistance correction method and adopts an NTC temperature compensation mechanism based on dual-algorithm temperature difference. Combined with the NTC temperature correction coefficient, it corrects the sampled temperature, effectively offsetting the errors of temperature sampling delay and thermal network model temperature response lag under transient conditions. It accurately captures the instantaneous temperature change characteristics of power devices and achieves rapid and accurate estimation of transient junction temperature through a simple correction formula. This significantly improves the real-time performance and accuracy of junction temperature estimation under dynamic operating conditions and sudden load changes in power modules, avoiding the risk of delayed over-temperature protection and instantaneous overheating damage to devices caused by inaccurate transient temperature estimation.

[0025] Optionally, the junction temperature calculation method of the thermal network method includes:

[0026] The device losses of each phase of the power module are calculated in real time, including MOSFET conduction losses, MOSFET switching losses, parasitic diode conduction losses, and diode reverse recovery losses. Combined with the real-time thermal resistance obtained from the Foster thermal resistance network model and the real-time sampling temperature of each phase's NTC, the losses are calculated using the formula... Calculate the initial junction temperature of each phase; where, This corresponds to the initial junction temperature of the phase. P represents the real-time thermal resistance of the power module, and P represents the total real-time device loss of the corresponding phase. For the corresponding NTC temperature Sampled value.

[0027] Optionally, the calculation method for the losses of each device is as follows:

[0028] MOSFET conduction loss: Based on the characteristic that MOSFETs have no inherent threshold voltage drop, a purely resistive loss formula is used. Calculate; where, Let be the MOSFET conduction loss at time t. Let be the instantaneous conduction equivalent resistance at time t. Let t be the collector current at time t, and δ be the duty cycle of the switch.

[0029] MOSFET switching losses: using the formula Calculate; where, The switching frequency of the MOSFET. Energy loss during a single main switch operation. The rated test current, The rated test voltage, For chip junction temperature, This is the peak value of the output current. This is the actual operating voltage of the DC bus;

[0030] Diode conduction loss: using the formula Calculate; where, Let be the diode conduction loss at time t. This is the forward threshold voltage drop of the diode. This is the forward threshold voltage drop of the diode. Let be the forward equivalent internal resistance of the diode at time t. Let t be the instantaneous load current of the diode at time t, and δ be the duty cycle of the switching transistor;

[0031] Diode reverse recovery loss: using the formula Calculate; where, This refers to the average reverse recovery loss of a single-phase diode. For switching frequency, This refers to the single reverse recovery energy of the diode.

[0032] P = MOSFET conduction loss + MOSFET switching loss + diode conduction loss + diode reverse recovery loss.

[0033] Optionally, the junction temperature estimation step of the high current saturation voltage drop method includes:

[0034] After power-on, the rated current is applied to the preset bridge arm and maintained for a preset duration. Multiple samples are taken to calculate the power transistor at room temperature. The average value is then taken, and the RDS(on) value is corrected for the entire current range by combining it with the calibration table.

[0035] Using the PWM frequency as the sampling frequency, the phase current and DESAT detection voltage signal are synchronously locked at the rising edge of the PWM.

[0036] Select light load [0, ±2A] and heavy load [0.95]. , The sampling data of the current range is obtained through the formula. Real-time computation ;in, This is the real-time drain-source on-resistance of the power transistor. To calibrate the original detection voltage, The inherent offset voltage is zero current. To synchronously sample and calibrate the current;

[0037] Based on RDS(on) and real-time phase current, the junction temperature of each phase is obtained by querying the pre-calibrated three-dimensional data table, and the maximum value of the three phases is taken as the initial junction temperature of the saturation voltage drop method; wherein, the pre-calibrated three-dimensional data table is an RDS(on)-phase current-junction temperature three-dimensional table.

[0038] Secondly, the present invention provides a power module junction temperature estimation device, comprising a memory and a controller. The memory stores a computer-readable program, which, when executed by the controller, implements the steps of the power module junction temperature estimation method of the present invention.

[0039] Thirdly, the power module of the present invention employs the power module junction temperature estimation device as described in the present invention.

[0040] Fourthly, the motor controller described in this invention employs the power module described in this invention.

[0041] Fifthly, the vehicle described in this invention employs a motor controller as described in this invention.

[0042] The beneficial effects of this invention are:

[0043] (1) The power module junction temperature estimation method combining the thermal network method and the high current saturation voltage drop method retains the advantages of the thermal network method in terms of stability, low load rate and high accuracy, while using the high current saturation voltage drop method to compensate for the disadvantages of the thermal network method, thereby improving the accuracy and response speed of junction temperature estimation.

[0044] (2) The junction temperature estimation algorithm provided in this application can reflect the failure of the power module package level, namely the failure of the bonding wire and the solder layer. The root cause of the bonding wire failure is the change of the RDS(on) of the power module. The thermal network method is decoupled from the RDS(on). The root cause of the solder layer failure is the change of the thermal resistance. The high current saturation voltage drop method is decoupled from the thermal resistance. Therefore, the junction temperature estimation by combining the two methods is more suitable for the junction temperature estimation of the power module. Attached Figure Description

[0045] Figure 1 This is a flowchart of the power module junction temperature estimation method in the embodiments of this application;

[0046] Figure 2 This diagram serves as proof of the NTC's delay under transient operating conditions in the embodiments of this application.

[0047] Figure 3 This is a schematic diagram of the correction principle under stable operating conditions in the embodiments of this application;

[0048] Figure 4 This is a schematic diagram illustrating the correction principle under transient conditions in the embodiments of this application;

[0049] Figure 5 This is a block diagram of the power module junction temperature estimation device in the embodiments of this application;

[0050] Figure 6 This is a block diagram of the power module in an embodiment of this application;

[0051] Figure 7 This is a block diagram of the motor controller in an embodiment of this application;

[0052] Figure 8 This is a block diagram of a vehicle in an embodiment of this application. Detailed Implementation

[0053] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0054] Traditional methods involve calculating the junction temperature using either the thermal network method or the high-current saturation voltage drop method. Specifically:

[0055] I. Calculation of junction temperature using the thermal network method alone includes:

[0056] The device losses of each phase of the power module are calculated in real time, including MOSFET conduction losses, MOSFET switching losses, parasitic diode conduction losses, and diode reverse recovery losses. Combined with the real-time thermal resistance obtained from the Foster thermal resistance network model and the real-time sampling temperature of each phase's NTC, the losses are calculated using the formula... Calculate the initial junction temperature of each phase; where, This corresponds to the initial junction temperature of the phase. P represents the real-time thermal resistance of the power module, and P represents the total real-time device loss of the corresponding phase. This corresponds to the NTC temperature sampling value.

[0057] Taking phase U as an example:

[0058]

[0059] in, This is the initial junction temperature of the U phase. The thermal resistance of the power module is typically obtained through simulation using a Foster thermal resistance network model, resulting in a thermal resistance curve that varies over time. P represents the total real-time device loss in the U-phase, calculated in real time. The temperature sampling value of the U-phase NTC is obtained through the NTC sensor.

[0060] The total losses of a power module during operation include MOSFET conduction losses, MOSFET switching losses, diode conduction losses, and diode reverse recovery losses, i.e., P = MOSFET conduction losses + MOSFET switching losses + diode conduction losses + diode reverse recovery losses.

[0061] (1) The specific calculation method for the losses of each device is as follows:

[0062] MOSFET conduction loss:

[0063]

[0064] Because MOSFETs have no inherent threshold voltage drop (i.e. ≈0), so the formula can be simplified to pure resistive loss:

[0065]

[0066] in, Let be the MOSFET conduction loss at time t; This is the drain-source on-state voltage drop (i.e., the voltage between the drain and source when the MOSFET is turned on). Let be the collector current at time t; The duty cycle of the switching transistor; This is the threshold voltage for IGBT saturation voltage drop. Let be the instantaneous conduction equivalent resistance at time t. I found it in the data manual.

[0067] MOSFET switching loss formula:

[0068]

[0069] in, For MOSFET switching losses; The switching frequency is the number of times the MOSFET turns on and off per second, expressed in Hz. Energy loss during a single main switch operation; The rated test current is the standard test current specified in the device datasheet or the double-pulse test calibration. The rated test voltage is the standard bus voltage used when calibrating the switching energy of the device. This refers to the junction temperature of the chip, which is the operating temperature of the PN junction inside the power semiconductor chip. The switching energy varies with the junction temperature. This refers to the peak value of the output current, which is the peak amplitude of the sinusoidal current output by the inverter. This refers to the actual operating voltage of the DC bus, which is the actual operating voltage of the DC side bus at the front end of the converter.

[0070] Diode conduction loss:

[0071]

[0072] in, The diode conduction loss at time t is the instantaneous conduction loss of the diode at time t, which is the instantaneous power loss generated during the forward conduction phase of the diode. This is the forward voltage drop of the diode, which is the voltage between the anode and cathode when the diode is turned on. Let t be the instantaneous load current flowing through the diode; This is the forward threshold voltage drop of the diode, which is the inherent turn-on threshold voltage of the diode under zero current. Let t be the forward equivalent internal resistance of the diode, which is the dynamic resistance of the diode during the conduction interval.

[0073] Diode reverse recovery loss:

[0074]

[0075] in, This refers to the average reverse recovery loss of a single-phase diode, which is the average switching loss generated during the reverse recovery process of the diode during the power frequency cycle. The switching frequency is the number of times a power device turns on and off per second. This refers to the single reverse recovery energy of the diode, which is the total energy consumed by the reverse recovery charge when the diode switches from conduction to turn-off; it is obtained from actual measurements using a double-pulse test.

[0076] (2) Junction temperature estimation: Collect the real-time chip junction temperature of all power devices (MOSFETs, freewheeling diodes) in the three-phase bridge arm, compare and select the maximum junction temperature as the final output junction temperature of the system, which is used for device temperature rise verification, power device thermal reliability verification, and overall thermal design evaluation.

[0077] II. Calculation of junction temperature using the high-current saturation voltage drop method alone includes:

[0078] (1) Control strategy: Taking TC397 and GD3162 chips as examples, GD3162 can collect the on-state voltage drop of the upper and lower bridge arms of the phase closest to the cooling water outlet of the power module (the chip temperature of the phase is estimated to be the highest) through the DESAT circuit.

[0079] ① Power-on self-learning: Due to the drain-source on-resistance between the same bridge arm of the same type of power module There are differences, therefore, it is necessary to conduct a current (the module's rated current) for approximately 500 microseconds on the selected bridge arm during power-up to test the power transistor at room temperature. The calculation (which can be performed 10 times and the average value is taken) is based on the calculation. Values ​​at the same current as in the calibration table The difference is calculated to determine the values ​​under different currents at room temperature. The value is corrected.

[0080] ② Phase current acquisition: The phase current sampling frequency is consistent with the PWM frequency. Since the sampling frequencies of phase current and on-state voltage drop are consistent with the PWM frequency, the higher the PWM frequency, the higher the calculation accuracy. Currently, it is tentatively set at 4~10KHz (TBC).

[0081] ③ The higher the motor speed, the faster the current changes. Therefore, the lower the motor speed, the higher the calculation accuracy. If the number of pole pairs of the motor is 4, the current speed is tentatively set at 2000~6000rpm (TBC).

[0082] ④ Voltage signal acquisition and Calculation: When the GD3162 detects the rising edge of the PWM, it will sample the on-state voltage drop. It records and locks the phase current and phase voltage sampled at the same time. In the database, when the phase current is in the range [0, ±2A], its on-state voltage drop is read; when the phase current is in the range [0.95I], its on-state voltage drop is read. max ,I max When [the voltage drop is reached], read the on-state voltage drop. Calculate using the following formula. .

[0083]

[0084] in, This is the real-time drain-source on-resistance of the power transistor (measured value for a single transistor). To calibrate the original detection voltage; The inherent offset voltage is zero current. To effectively calibrate the current.

[0085] ⑤ Junction temperature estimation: based on Real-time phase current, query the pre-calibrated three-dimensional data table to obtain the junction temperature of each phase, and take the maximum value of the three phases as the initial junction temperature of the saturation voltage drop method; the pre-calibrated three-dimensional data table is the RDS(on)-phase current-junction temperature three-dimensional table.

[0086] III. Comprehensive Junction Temperature Estimation Strategy: For devices with bond wire failure, the aging of the bond wires increases the contact resistance between the chip bond wires, leading to a higher saturation voltage drop (Vce) under the same current and junction temperature conditions. This change causes the error in junction temperature calculation using the high-current saturation voltage drop method to gradually increase as the bond wires age. Therefore, for devices with bond wire failure, the thermal network method is more suitable for junction temperature monitoring, providing more accurate online junction temperature calculations. On the other hand, for devices with solder failure, solder aging increases the thermal resistance of the device. When using the thermal network method, the calculated thermal resistance value is usually underestimated. Especially when approaching solder failure, the thermal resistance increases exponentially, resulting in a large error in the junction temperature calculation. Therefore, for devices with solder failure, the high-current saturation voltage drop method is more suitable for junction temperature monitoring, effectively reducing the measurement error caused by solder aging.

[0087] To overcome the limitations of a single calculation method, and to ensure the accuracy of junction temperature estimation under all operating conditions while covering various package-level failure issues of power modules, this application couples two junction temperature estimation methods.

[0088] like Figure 1 As shown in the embodiments of this application, a method for estimating the junction temperature of a power module includes the following steps:

[0089] S1. Real-time acquisition of the operating parameters of each of the three phase arms of the power module, and estimation of the initial junction temperature of the corresponding power device for each phase using the thermal network method and the high current saturation voltage drop method.

[0090] S2. Identify whether the current operating condition is steady-state or transient based on the real-time operating parameters of the power module.

[0091] S3. Based on the identified operating condition type, a differentiated correction strategy is adopted to compensate and correct the initial junction temperature of each phase output by the thermal network method, so as to obtain the final junction temperature of each phase power device.

[0092] S4. Extract the final junction temperature corresponding to all power devices in the three-phase bridge arm, and select the junction temperature with the largest value as the system output junction temperature.

[0093] The differentiated correction strategies include steady-state correction strategies and transient correction strategies:

[0094] The steady-state correction strategy is as follows: the temperature difference between the single-phase junction temperature output by the high-current saturation voltage drop method and the single-phase initial junction temperature output by the thermal network method is used as the correction benchmark to compensate and correct the thermal resistance loss term in the thermal network method.

[0095] The transient correction strategy is as follows: the temperature difference between the single-phase junction temperature output by the high current saturation voltage drop method and the single-phase initial junction temperature output by the thermal network method is used as the correction benchmark to compensate and correct the NTC sampling temperature involved in the calculation in the thermal network method.

[0096] The specific execution strategies under different operating conditions are divided as follows:

[0097] (1) Stable operating conditions

[0098] The steady-state operating condition is when the power module reaches thermal equilibrium. At this point, the power module temperature changes slowly, the speed is low, and the operation is relatively stable. The control strategy under this condition primarily uses the thermal network method to estimate the junction temperature, supplemented by the high-current saturation voltage drop method to correct the junction temperature estimated by the thermal network method.

[0099] Because the high current saturation voltage drop method has high accuracy near the rated current and at low speeds, it is suitable for use when the motor assembly meets the following conditions. Calculation, look up the table ( The junction temperature is obtained and output by using a table showing the relationship between phase current and junction temperature.

[0100] In one possible embodiment, the steady-state condition determination criterion is:

[0101] The effective value of any phase current of the power module is in the range of 0.8 to 1.2 times the rated current, the effective value change rate of the phase current is less than the first preset threshold, and the motor speed is in the range of 1000 to 3000 rpm.

[0102] like Figure 3 As shown, the correction strategy under steady-state conditions is as follows: Calculate the temperature difference between the single-phase junction temperature output by the high-current saturation voltage drop method and the single-phase initial junction temperature output by the thermal network method under steady-state conditions. Based on temperature difference Constructing thermal resistance loss compensation terms , To match temperature difference The obtained thermal resistance correction coefficient is dynamically updated with the aging time of the power module. The thermal resistance loss compensation term is superimposed on the original calculation formula of the thermal network. Using the corrected formula Obtain the final temperature of the corresponding phase .

[0103] Taking phase U as an example, the junction temperature estimated based on the high current saturation voltage drop method and the junction temperature estimated based on the thermal network method are compared. Temperature difference Constructing thermal resistance loss compensation terms The thermal resistance of the thermal network method is corrected and updated.

[0104] The revised formula for estimating junction temperature is as follows:

[0105]

[0106] in, This is the corrected U-phase junction temperature; The thermal resistance of the power module is generally obtained through simulation using the Foster thermal resistance network model, which will yield a thermal resistance curve that changes over time. The total real-time device loss for the U-phase is obtained through real-time calculation. This is a thermal resistance correction factor, which is continuously updated as the power module ages. The NTC temperature of the U phase is sampled and obtained through an NTC sensor.

[0107] (2) Transient operating conditions: Under transient operating conditions, the error of the thermal network method mainly comes from the sampling delay of the NTC. See Figure 2 During the process of current change, the temperature of NTC cannot change in time. However, under transient conditions, the response speed of large current saturation voltage drop is fast, which can reduce the error under transient conditions and provide precise protection for the power module. Moreover, the temperature threshold of the power module can be increased from the current 150℃ to 160℃ (TBC).

[0108] The transient operating condition is determined by meeting any of the following conditions: the actual torque change rate of the motor is greater than 5000 Nm / s, the speed change rate is greater than 80 r / s², and the effective value change rate of the phase current is greater than 50 Arms / s.

[0109] like Figure 4 As shown, the transient correction strategy is to calculate the difference in junction temperature between the high-current saturation voltage drop method and the thermal network method under transient conditions. ,

[0110] Based on temperature difference Constructing NTC temperature compensation terms , To match temperature difference The obtained NTC temperature correction coefficient is then added to the original calculation formula for the thermal network. Using the corrected formula Obtain the final temperature of the corresponding phase .

[0111] Taking phase U as an example, the junction temperature estimated based on the high current saturation voltage drop method and the junction temperature estimated based on the thermal network method are compared. The NTC temperature of the heat network method is corrected and updated:

[0112]

[0113] The temperature correction factor for the NTC needs to be calibrated in advance to ensure the real-time performance and accuracy of temperature estimation. Calibration is required based on different collector currents and bus voltages, where I and U represent the rated current and rated voltage, respectively.

[0114] Since conduction losses increase exponentially with increasing current, and switching losses also increase with increasing current, the power module's losses increase rapidly with increasing current, and the rate of increase accelerates with increasing current. The correction factor should trend towards increasing values. The same applies to bus voltage.

[0115] Based on software control strategies and the functions of the hardware chip itself, this application proposes a power module junction temperature estimation method that combines the thermal network method and the high current saturation voltage drop method. When identifying steady-state and instantaneous operating conditions, the junction temperature is corrected based on the different characteristics of the operating conditions to improve the accuracy of the operating conditions across all operating conditions.

[0116] Based on the characteristics of the high current saturation voltage drop method, this application has high accuracy near the rated current. Therefore, under steady-state conditions and after meeting the relevant requirements, the thermal resistance of the thermal network method is corrected based on the difference in junction temperature estimated by the high current saturation voltage drop method and the thermal network method.

[0117] Because the NTC exhibits strong hysteresis under instantaneous operating conditions, and the high current saturation voltage drop method is decoupled from the NTC temperature sensor, the NTC value is corrected based on the difference in junction temperature estimated by the high current saturation voltage drop method and the thermal network method when instantaneous operating conditions are met.

[0118] Please see Figure 5 In this embodiment of the application, a power module junction temperature estimation device includes a memory and a controller. The memory stores a computer-readable program, and when the computer-readable program is executed by the controller, it implements the steps of the power module junction temperature estimation method of this application.

[0119] Please see Figure 6 In this embodiment of the application, a power module employs the power module junction temperature estimation device as described in this application.

[0120] Please see Figure 7 In this embodiment of the application, a motor controller uses the power module as described in this application.

[0121] Please see Figure 8 In one embodiment of this application, a vehicle employs a motor controller as described in this application.

[0122] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for estimating the junction temperature of a power module, characterized in that, Includes the following steps: Real-time acquisition of the operating parameters of each of the three-phase bridge arms of the power module; and estimation of the initial junction temperature of the corresponding power device for each phase using the thermal network method and the high current saturation voltage drop method. Based on the real-time operating parameters of the power module, the current operating condition can be identified as either steady-state or transient. Based on the identified operating condition type, a differentiated correction strategy is adopted to compensate and correct the initial junction temperature of each phase output by the thermal network method, thereby obtaining the final junction temperature of each phase power device. Extract the final junction temperature of all power devices in the three-phase bridge arm, and select the junction temperature with the largest value as the system output junction temperature; The differentiated correction strategy includes a steady-state correction strategy and a transient correction strategy: The steady-state correction strategy is as follows: the temperature difference between the single-phase junction temperature output by the high-current saturation voltage drop method and the single-phase initial junction temperature output by the thermal network method is used as the correction benchmark to compensate and correct the thermal resistance loss term in the thermal network method. The transient correction strategy is as follows: using the temperature difference between the single-phase junction temperature output by the high-current saturation voltage drop method and the single-phase initial junction temperature output by the thermal network method as the correction benchmark, the NTC sampling temperature involved in the calculation in the thermal network method is compensated and corrected.

2. The power module junction temperature estimation method according to claim 1, characterized in that, The criteria for determining the steady-state operating condition are as follows: The effective value of any phase current of the power module is in the range of 0.8 to 1.2 times the rated current, the effective value change rate of the phase current is less than the first preset threshold, and the motor speed is in the range of 1000 to 3000 rpm. The steady-state correction strategy is as follows: The temperature difference between the single-phase junction temperature calculated by the high-current saturation voltage drop method and the single-phase initial junction temperature calculated by the thermal network method under steady-state conditions is calculated. ; Based on the temperature difference Constructing thermal resistance loss compensation terms , To match the temperature difference The obtained thermal resistance correction coefficient is dynamically updated as the power module ages. The thermal resistance loss compensation term is superimposed onto the original calculation formula of the thermal network. Using the corrected formula The final temperature of the corresponding phase is obtained.

3. The power module junction temperature estimation method according to claim 1, characterized in that, The condition for determining the transient operating condition is that any of the following conditions are met: The actual torque change rate of the motor is greater than 5000 Nm / s, the speed change rate is greater than 80 r / s², and the effective value change rate of the phase current is greater than 50 Arms / s; The transient correction strategy is as follows: under transient operating conditions, calculate the difference in junction temperature between the high-current saturation voltage drop method and the thermal network method. , Based on the temperature difference Constructing NTC temperature compensation terms , To match the temperature difference The obtained NTC temperature correction factor; The NTC temperature compensation term is superimposed onto the original calculation formula of the thermal network. Using the corrected formula The final temperature of the corresponding phase is obtained.

4. The power module junction temperature estimation method according to claim 1, characterized in that, The junction temperature calculation method of the thermal network method includes: The device losses of each phase of the power module are calculated in real time, including MOSFET conduction losses, MOSFET switching losses, parasitic diode conduction losses, and diode reverse recovery losses. Combined with the real-time thermal resistance obtained from the Foster thermal resistance network model and the real-time sampling temperature of each phase's NTC, the losses are calculated using the formula... Calculate the initial junction temperature of each phase; where, This corresponds to the initial junction temperature of the phase. P represents the real-time thermal resistance of the power module, and P represents the total real-time device loss of the corresponding phase. For the corresponding NTC temperature Sampled value.

5. The power module junction temperature estimation method according to claim 4, characterized in that, The specific calculation method for the losses of each component is as follows: MOSFET conduction loss: Based on the characteristic that MOSFETs have no inherent threshold voltage drop, a purely resistive loss formula is used. Calculate; where, Let be the MOSFET conduction loss at time t. Let be the instantaneous conduction equivalent resistance at time t. Let t be the collector current at time t, and δ be the duty cycle of the switch. MOSFET switching losses: using the formula Calculate; where, The switching frequency of the MOSFET. Energy loss during a single main switch operation. The rated test current, The rated test voltage, For chip junction temperature, This is the peak value of the output current. This is the actual operating voltage of the DC bus; Diode conduction loss: using the formula Calculate; where, Let be the diode conduction loss at time t. This is the forward threshold voltage drop of the diode. This is the forward threshold voltage drop of the diode. Let be the forward equivalent internal resistance of the diode at time t. Let t be the instantaneous load current of the diode at time t, and δ be the duty cycle of the switching transistor; Diode reverse recovery loss: using the formula Calculate; where, This refers to the average reverse recovery loss of a single-phase diode. For switching frequency, This refers to the single reverse recovery energy of the diode. P = MOSFET conduction loss + MOSFET switching loss + diode conduction loss + diode reverse recovery loss.

6. The power module junction temperature estimation method according to claim 1, characterized in that, The junction temperature estimation steps of the high current saturation voltage drop method include: After power-on, the rated current is applied to the preset bridge arm and maintained for a preset duration. Multiple samples are taken to calculate the power transistor at room temperature. The average value is then taken, and the RDS(on) value is corrected for the entire current range by combining it with the calibration table. Using the PWM frequency as the sampling frequency, the phase current and DESAT detection voltage signal are synchronously locked at the rising edge of the PWM. Select light load [0, ±2A] and heavy load [0.95]. , The sampling data of the current range is obtained through the formula. Real-time computation ;in, This is the real-time drain-source on-resistance of the power transistor. To calibrate the original detection voltage, The inherent offset voltage is zero current. To synchronously sample and calibrate the current; Based on RDS(on) and real-time phase current, the junction temperature of each phase is obtained by querying the pre-calibrated three-dimensional data table, and the maximum value of the three phases is taken as the initial junction temperature of the saturation voltage drop method; wherein, the pre-calibrated three-dimensional data table is an RDS(on)-phase current-junction temperature three-dimensional table.

7. A power module junction temperature estimation device, characterized in that, The device includes a memory and a controller, wherein the memory stores a computer-readable program that, when executed by the controller, implements the steps of the power module junction temperature estimation method according to any one of claims 1-6.

8. A power module, characterized in that, The power module junction temperature estimation device as described in claim 7 is used.

9. A motor controller, characterized in that, The power module as described in claim 8 is used.

10. A vehicle, characterized in that, The motor controller as described in claim 9 is used.

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