An IGBT thermal failure management method, a voltage regulating circuit and an electrical device

Abstract

The application discloses an IGBT thermal failure management method, a voltage regulating circuit and a power utilization device. The IGBT thermal failure management method comprises the following steps: collecting real-time operation parameters of an IGBT, and calculating total transient loss of the IGBT according to the real-time operation parameters; acquiring a reference thermal resistance of the IGBT, and calculating a real-time thermal resistance of the IGBT according to historical operation parameters of the IGBT; collecting a real-time shell temperature of the IGBT, and calculating a real-time junction temperature of the IGBT according to the real-time shell temperature, the total transient loss and the real-time thermal resistance; and triggering an IGBT protection strategy when the real-time junction temperature of the IGBT reaches a threshold temperature. Compared with the prior art, the application can reduce the junction temperature estimation error of the IGBT and ensure the system operation reliability through the double-source coupling of the instantaneous characteristics and the real-time shell temperature and the dynamic thermal resistance compensation algorithm.

Description

Technical Field

[0001] This invention relates to the field of switch control circuits, and in particular to an IGBT thermal failure management method, voltage regulation circuit, and electrical equipment. Background Technology

[0002] With the rapid development of new energy power generation, electric vehicles, rail transit and smart grids, the reliability of insulated gate bipolar transistors (IGBTs), as the core power switching devices of power electronic systems, has become a key factor restricting the safe operation of the system.

[0003] IGBTs achieve efficient power conversion and control through high-frequency switching. However, the long-term accumulation of thermal and mechanical stresses generated during operation significantly increases the failure risk of critical components such as chips, bonding wires, and solder layers. Statistics show that approximately 55% of failures in power electronic equipment originate from IGBT thermal failures. Failure modes such as thermal runaway, solder voids, and bonding wire peeling are directly related to drastic fluctuations in device junction temperature and long-term thermal cycling. Especially under extreme conditions, the junction temperature fluctuation of IGBTs can reach over 80°C, accelerating material interface aging and electrothermal characteristic degradation, ultimately leading to catastrophic failure.

[0004] Existing IGBT thermal management strategies mainly rely on a single case temperature sensor (NTC / PTC) or estimation model. Relying solely on the case temperature sensor cannot reflect the transient changes in the junction temperature (Tj) inside the IGBT in real time, especially under high-frequency switching conditions, where heat conduction has a time delay. DSP control often uses fixed thermal resistance parameters, ignoring the nonlinear drift of thermal resistance caused by the aging of the solder layer inside the IGBT and the nonlinear impact of current waveform distortion on switching losses.

[0005] Therefore, how to design an IGBT thermal failure management method, voltage regulation circuit and electrical equipment to ensure the real-time and accuracy of IGBT junction temperature estimation is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0006] To address the shortcomings of existing technologies in terms of the real-time performance and accuracy of IGBT junction temperature detection, this invention proposes an IGBT thermal failure management method, a voltage regulation circuit, and an electrical device.

[0007] The technical solution of the present invention is to propose an IGBT thermal failure management method, comprising: collecting real-time operating parameters of the IGBT, and calculating the total transient loss of the IGBT based on the real-time operating parameters;

[0008] Obtain the reference thermal resistance of the IGBT, and calculate the real-time thermal resistance of the IGBT based on the historical operating parameters of the IGBT;

[0009] The real-time case temperature of the IGBT is collected, and the real-time junction temperature of the IGBT is calculated based on the real-time case temperature, the total transient loss, and the real-time thermal resistance.

[0010] When the real-time junction temperature of the IGBT reaches the threshold temperature, the IGBT protection strategy is triggered.

[0011] In the above-described scheme, the present invention calculates the real-time junction temperature of the IGBT using real-time case temperature, total transient loss, and real-time thermal resistance. The calculation process integrates the dual-source coupling of total transient loss and real-time case temperature, as well as the real-time thermal resistance obtained by dynamic compensation of the reference thermal resistance. This can improve the accuracy of the calculation of the real-time junction temperature of the IGBT while ensuring the real-time performance of the acquisition, and reduce the estimation error of the real-time junction temperature of the IGBT.

[0012] Furthermore, the calculation model for the total transient loss of the IGBT is: ptot(t) = Pcond(t) + Psw(t);

[0013] Where ptot(t) is the total transient loss of the IGBT, Pcond(t) is the conduction loss of the IGBT, and Psw(t) is the switching loss of the IGBT.

[0014] This invention considers both the IGBT's conduction loss and switching loss when calculating the total transient loss of the IGBT. The conduction loss is the loss generated when the IGBT is turned on, while the switching loss is the unnecessary energy loss generated when the IGBT is turned on and off. By combining the IGBT's conduction loss and switching loss to calculate the total transient loss, this invention can provide a more comprehensive feedback on the IGBT's loss data throughout the entire operation process. Furthermore, by combining this with the real-time thermal resistance to update the IGBT's real-time case temperature, the accuracy of the calculation of the IGBT's real-time junction temperature can be further improved.

[0015] Furthermore, the real-time operating parameters include: the saturation voltage drop of the IGBT, the real-time collector current of the IGBT, and the duty cycle of the IGBT;

[0016] The calculation model for the conduction loss of the IGBT is: Pcond(t) = Vce_sat(t) * Ic(t) * D;

[0017] Where Pcond(t) is the conduction loss of the IGBT, Vce_sat(t) is the saturation voltage drop of the IGBT, Ic(t) is the collector current of the IGBT, and D is the duty cycle of the IGBT.

[0018] This invention provides a clear calculation process for conduction loss through the above-described scheme. This conduction loss can not only be used for subsequent calculation of total transient loss, thereby updating the real-time junction temperature of the IGBT, but also for optimizing the system based on the conduction loss of the IGBT. Based on the clear understanding of conduction loss, those skilled in the art can judge the state of the entire IGBT according to the proportion of conduction loss. If the conduction loss is too high, the conduction resistance can be appropriately reduced to optimize system efficiency, which helps to achieve better performance and value.

[0019] Furthermore, the real-time operating parameters also include: the bus voltage of the IGBT and the turn-off time of the IGBT;

[0020] The calculation model for the switching loss of the IGBT is: Psw(t)=[Vdc*Ic(t)*toff] / 2;

[0021] Where Psw(t) is the switching loss of the IGBT, Vdc is the bus voltage of the IGBT, Ic(t) is the collector current of the IGBT, and tof is the turn-off time of the IGBT.

[0022] This invention provides a clear calculation process for switching losses through the above-described scheme. These switching losses can not only be used for subsequent calculations of total transient losses, thereby updating the real-time junction temperature of the IGBT, but also for optimizing design parameters. This helps those skilled in the art to adjust power supply design parameters and control strategies, achieving higher work efficiency. Furthermore, based on the calculation of switching losses, it can also provide corresponding data support for soft-switching technology, reducing the overall loss of the IGBT.

[0023] Furthermore, the calculation model for the real-time thermal resistance of the IGBT is: Rth_real(t) = Rth_base × [1 + a(t)];

[0024] Where Rth_real(t) is the real-time thermal resistance of the IGBT, Rth_base is the reference thermal resistance of the IGBT, and a(t) is the update factor.

[0025] This invention obtains real-time thermal resistance by adding an update factor to the reference thermal resistance of IGBT. Firstly, it solves the problem that thermal resistance increases due to solder voiding while temperature acquisition data remains unchanged. Secondly, it can construct a dynamic thermal resistance compensation mechanism, establish a three-dimensional mapping table of "real-time case temperature, current density, and running time", and correct the thermal resistance coefficient in real time, thus ensuring the accuracy of the calculation of total instantaneous loss.

[0026] Furthermore, the historical operating parameters include: the cumulative operating time of the IGBT, the highest junction temperature cycle count, and the deviation between the real-time case temperature of the IGBT and the theoretical value;

[0027] The update factor is configured to update adaptively based on the historical running data.

[0028] Through the above-mentioned scheme, the present invention adaptively updates the update factor, which can construct a dynamic thermal resistance compensation mechanism, establish a three-dimensional mapping table of "real-time shell temperature, current density, and running time", correct the thermal resistance coefficient in real time, and ensure the accuracy of the calculation of total instantaneous loss.

[0029] Furthermore, the calculation model for the real-time junction temperature of the IGBT is: Tj(t) = Tc(t) + Ptot(t) × Rth_real(t);

[0030] Where Tj(t) is the real-time junction temperature of the IGBT, Tc(t) is the real-time case temperature of the IGBT, Pcond(t) is the conduction loss of the IGBT, and Rth_real(t) is the real-time thermal resistance of the IGBT.

[0031] In the above-described scheme, the present invention calculates the real-time junction temperature of the IGBT using real-time case temperature, total transient loss, and real-time thermal resistance. The calculation process integrates the dual-source coupling of total transient loss and real-time case temperature, as well as the real-time thermal resistance obtained by dynamic compensation of the reference thermal resistance. This can improve the accuracy of the calculation of the real-time junction temperature of the IGBT while ensuring the real-time performance of the acquisition, and reduce the estimation error of the real-time junction temperature of the IGBT.

[0032] Furthermore, the threshold temperature is configured to be 90% of the highest junction temperature of the IGBT.

[0033] This invention sets the threshold temperature at 90% of the highest junction temperature of the IGBT, which can transform the original "passive melting" control mechanism into an "active derating" control mechanism before thermal failure. By adjusting the duty cycle of the IGBT in advance, the real-time current of the collector electrode of the IGBT is reduced, thereby achieving active cooling and avoiding catastrophic damage caused by IGBT thermal failure, thus improving the safety and reliability of the system.

[0034] Furthermore, the IGBT protection strategy includes: reducing the duty cycle of the IGBT; when the duty cycle of the IGBT is at its lowest, reducing the on-frequency of the IGBT or turning off the IGBT.

[0035] This invention clarifies the protection strategy for IGBTs through the above-described scheme. Compared to traditional schemes that protect the IGBT after it has already suffered thermal failure, this invention proactively reduces the IGBT's duty cycle in advance, directly preventing the IGBT's real-time junction temperature from reaching the temperature that would cause thermal failure. This fundamentally eliminates the problem of thermal failure and avoids a series of subsequent control anomalies caused by IGBT thermal failure. Furthermore, if adjusting the duty cycle fails to reduce the IGBT's real-time junction temperature to the threshold temperature, this invention further reduces the IGBT's on-frequency or even directly turns off the IGBT. This process is equivalent to secondary protection, further preventing IGBT thermal failure and ensuring the reliability and safety of the entire system.

[0036] Furthermore, the present invention also proposes a voltage regulation circuit, comprising:

[0037] A full-wave rectifier module, including a high-voltage output terminal and a low-voltage output terminal, is adapted to convert an input AC signal into a DC signal;

[0038] A power factor correction module is electrically connected to the full-wave rectifier module and includes a first half-bridge assembly, a second half-bridge assembly, and an inductive element disposed between the first half-bridge assembly and the second half-bridge assembly. The first half-bridge assembly is disposed between the low-voltage output terminal and the high-voltage output terminal. The second half-bridge assembly includes a plurality of power transistors connected in series. One of the plurality of power transistors is connected to the first half-bridge assembly. One end of the inductive element is connected to any connection point among the plurality of power transistors, and the other end of the inductive element is connected to a designated position of the first half-bridge assembly. The power factor correction module is adapted to configure the DC signal as a bus voltage according to a switch control signal. The bus voltage is boosted or bucked relative to the DC signal. The two ends of the second half-bridge assembly are configured as the output terminals of the bus voltage.

[0039] The power transistor is an IGBT, and each IGBT is equipped with a controller. When the controller is working, it executes the above-mentioned IGBT thermal failure management method.

[0040] In the above technical solution, the present invention includes a full-wave rectifier module comprising a transformer with taps, a first power transistor and a second power transistor connected in series, the first power transistor and the second power transistor being disposed between the two coil output terminals of the transformer, and one of the connection terminals between the first power transistor and the second power transistor and the tap being configured as the low-voltage output terminal of the full-wave rectifier module, and the other being configured as the high-voltage output terminal.

[0041] The power factor correction module also includes capacitive elements connected to both ends of the second half-bridge assembly.

[0042] In this scheme, the voltage regulation circuit includes a full-wave rectification module and a power factor correction module. The full-wave rectification module includes a transformer, a first power transistor, and a second power transistor. By setting a tap, the transformer has three output terminals. Among them, one of the taps serves as a fixed low-voltage output terminal, while the other two output terminals are connected to the first power transistor and the second power transistor, respectively. During the positive half-cycle of the AC signal, the current flows to the high-voltage output terminal through one output terminal and one of the power transistors. During the negative half-cycle of the AC signal, the current flows to the high-voltage output terminal through the other output terminal and the other power transistor. By combining the switching control of the first power transistor and the second power transistor, full-wave rectification can be achieved.

[0043] Meanwhile, the present invention uses IGBTs for all power switching transistors in the above scheme, and configures a corresponding controller to execute the above IGBT thermal failure management method. This can avoid the problem of IGBT thermal failure while ensuring the basic working logic of the voltage regulation circuit, and further ensure the reliability and safety of the voltage regulation circuit.

[0044] Furthermore, a sampling resistor is connected in series in the switching branch of each IGBT, and the sampling resistor is used to collect the real-time collector current of the IGBT.

[0045] A thermistor is also provided on the housing of the IGBT, which is used to collect the real-time housing temperature of the IGBT.

[0046] By setting the sampling resistor as described above, this invention can detect the magnitude of the current in real time, thereby obtaining the real-time collector current of the IGBT for subsequent real-time junction temperature calculation. In addition, based on the setting of the sampling resistor, when an overcurrent problem occurs in the circuit, the voltage on the sampling resistor will rise sharply. By detecting this voltage change, the circuit overcurrent problem can be detected in time, thereby triggering the protection mechanism, avoiding circuit damage, and improving the safety of the entire system.

[0047] Furthermore, by placing the thermistor on the IGBT housing, this invention ensures good heat exchange between the thermistor and the IGBT housing, thereby guaranteeing the accuracy of the real-time housing temperature data acquired by the thermistor and ensuring the accuracy of subsequent calculations of the real-time junction temperature.

[0048] Furthermore, the electrical equipment has the aforementioned voltage regulation circuit.

[0049] This invention, by configuring the aforementioned voltage regulation circuit for electrical equipment, can solve the problem that current power factor correction circuits only have boost or buck functions, which cannot meet the needs of bus voltage regulation and thus result in low operating efficiency.

[0050] Furthermore, the electrical equipment is an air conditioner.

[0051] This invention further expands the aforementioned electrical equipment to air conditioners, which can ensure the operating efficiency of the air conditioning system, meet user needs, and enhance market competitiveness.

[0052] Compared with the prior art, the present invention has at least the following beneficial effects:

[0053] 1. This invention calculates the real-time junction temperature of IGBT by using real-time case temperature, total transient loss, and real-time thermal resistance. The calculation process integrates the dual-source coupling of total transient loss and real-time case temperature, as well as the real-time thermal resistance obtained by dynamic compensation of the reference thermal resistance. This can improve the accuracy of the calculation of the real-time junction temperature of IGBT while ensuring the real-time performance of the IGBT, and reduce the estimation error of the real-time junction temperature of IGBT.

[0054] 2. By setting the threshold temperature at 90% of the highest junction temperature of the IGBT, this invention can transform the original "passive melting" control mechanism into an "active derating" control mechanism before thermal failure. By adjusting the duty cycle of the IGBT in advance, the real-time current of the collector electrode of the IGBT is reduced, thereby achieving active cooling and avoiding catastrophic damage caused by IGBT thermal failure, thus improving the safety and reliability of the system. Attached Figure Description

[0055] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 This is a flowchart illustrating the overall process of the IGBT thermal failure management method of the present invention.

[0057] Figure 2 This is a control flowchart of the IGBT thermal failure management method of the present invention in a specific example;

[0058] Figure 3 This is the specific process for calculating the total transient loss of the IGBT in this invention;

[0059] Figure 4 This is the specific process for calculating the real-time junction temperature of the IGBT in this invention;

[0060] Figure 5 This is a control flowchart for triggering the IGBT protection strategy in this invention;

[0061] Figure 6 This is a schematic diagram of the topology of the voltage regulation circuit in this invention;

[0062] Figure 7 This is a schematic diagram of the topology of the full-wave rectifier module in this invention;

[0063] Figure 8 This is a topological schematic diagram of the power factor correction module in this invention;

[0064] Among them, 10 is a full-wave rectifier module and 20 is a power factor correction module. Detailed Implementation

[0065] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0066] Therefore, a feature pointed out in this specification is used to describe one feature of one embodiment of the invention, and does not imply that every embodiment of the invention must have the described feature. Furthermore, it should be noted that this specification describes many features. Although certain features may be combined to illustrate possible system designs, these features may also be used in other combinations not explicitly stated. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0067] The principles and structure of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0068] IGBTs achieve efficient power conversion and control through high-frequency switching. However, the long-term accumulation of thermal and mechanical stresses generated during operation significantly increases the failure risk of critical components such as chips, bonding wires, and solder layers. Statistics show that approximately 55% of failures in power electronic equipment originate from IGBT thermal failures. Failure modes such as thermal runaway, solder voids, and bonding wire peeling are directly related to drastic fluctuations in device junction temperature and long-term thermal cycling. Especially under extreme conditions, the junction temperature fluctuation of IGBTs can reach over 80°C, accelerating material interface aging and electrothermal characteristic degradation, ultimately leading to catastrophic failure.

[0069] Existing IGBT thermal management strategies mainly rely on a single case temperature sensor (NTC / PTC) or estimation model. Relying solely on the case temperature sensor cannot reflect the transient changes in the junction temperature inside the IGBT in real time, especially under high-frequency switching conditions, where heat conduction has a time delay. DSP control often uses fixed thermal resistance parameters, ignoring the nonlinear drift of thermal resistance caused by the aging of the solder layer inside the IGBT and the nonlinear impact of current waveform distortion on switching losses.

[0070] To address the aforementioned issues, this invention proposes an IGBT thermal failure management method. Addressing the problem that relying solely on case temperature sensors cannot reflect the transient changes in the IGBT's internal junction temperature in real time, this invention utilizes a dual-source coupling method of total transient loss and real-time case temperature for calculation, thus avoiding the inaccurate results due to time delays in heat conduction.

[0071] To address the issues of neglecting the nonlinear drift of thermal resistance caused by the aging of the solder layer inside the IGBT and the nonlinear impact of current waveform distortion on switching losses when using fixed thermal resistance parameters, this invention corrects the thermal resistance coefficient in real time by dynamically compensating for the reference thermal resistance, thus solving the problem of unchanged temperature acquisition data caused by increased thermal resistance due to solder voiding.

[0072] Please see Figure 1 Based on the above design concept, the IGBT thermal failure management method provided by the present invention includes: collecting the real-time operating parameters of the IGBT and calculating the total transient loss of the IGBT based on the real-time operating parameters;

[0073] Obtain the reference thermal resistance of the IGBT and calculate the real-time thermal resistance of the IGBT based on the historical operating parameters of the IGBT.

[0074] The real-time case temperature of the IGBT is collected, and the real-time junction temperature of the IGBT is calculated based on the real-time case temperature, total transient loss, and real-time thermal resistance.

[0075] When the real-time junction temperature of the IGBT reaches the threshold temperature, the IGBT protection strategy is triggered.

[0076] Specifically, addressing the issue mentioned above that relying on a case temperature sensor cannot reflect the transient changes in the internal junction temperature of an IGBT in real time, this invention, in the above solution, after obtaining the real-time case temperature, performs dual-source coupling calculation by combining the total transient loss and the real-time thermal resistance. Compared to the traditional solution that directly uses the real-time case temperature obtained by the case temperature sensor to determine the real-time junction temperature, this invention adds a method to determine the real-time junction temperature by using the total transient loss and the real-time thermal resistance. This additional increment is equivalent to superimposing the increase in the heat conduction delay, thereby enabling the real-time junction temperature obtained by this invention to reflect the transient changes in the internal real-time junction temperature accurately and without delay, avoiding the problem of inaccurate real-time junction temperature parameters obtained due to the delay in heat conduction time in the traditional solution.

[0077] Furthermore, regarding the thermal resistance of the IGBT, the present invention eliminates the scheme of using a fixed reference thermal resistance for calculation in the above solution. Instead, it updates the real-time thermal resistance of the IGBT based on historical operating parameters. During the update process, the nonlinear drift of thermal resistance caused by the aging of the solder layer inside the IGBT is taken into account, so that the final real-time thermal resistance can truly reflect the thermal resistance coefficient of the IGBT and avoid the problem of calculation error caused by the increase of thermal resistance while the temperature acquisition data remains unchanged.

[0078] In summary, the present invention calculates the real-time junction temperature of the IGBT by using real-time case temperature, total transient loss, and real-time thermal resistance. The calculation process integrates the dual-source coupling of total transient loss and real-time case temperature, as well as the real-time thermal resistance obtained by dynamic compensation of the reference thermal resistance. This can improve the accuracy of the calculation of the real-time junction temperature of the IGBT while ensuring the real-time performance of the acquisition, and reduce the estimation error of the real-time junction temperature of the IGBT.

[0079] The calculation models for each parameter are explained below;

[0080] Specifically, the calculation model for the total transient loss of an IGBT is: ptot(t) = Pcond(t) + Psw(t);

[0081] Where ptot(t) is the total transient loss of the IGBT, Pcond(t) is the conduction loss of the IGBT, and Psw(t) is the switching loss of the IGBT.

[0082] This invention considers both the IGBT's conduction loss and switching loss when calculating the total transient loss of the IGBT. The conduction loss is the loss generated when the IGBT is turned on, while the switching loss is the unnecessary energy loss generated when the IGBT is turned on and off. By combining the IGBT's conduction loss and switching loss to calculate the total transient loss, this invention can provide a more comprehensive feedback on the IGBT's loss data throughout the entire operation process. Furthermore, by combining this with the real-time thermal resistance to update the IGBT's real-time case temperature, the accuracy of the calculation of the IGBT's real-time junction temperature can be further improved.

[0083] In order to obtain the conduction loss of the IGBT, the real-time operating parameters collected in this invention include: the saturation voltage drop of the IGBT, the real-time collector current of the IGBT, and the duty cycle of the IGBT.

[0084] Specifically, the calculation model for the conduction loss of an IGBT is: Pcond(t) = Vce_sat(t) * Ic(t) * D;

[0085] Where Pcond(t) is the conduction loss of the IGBT, Vce_sat(t) is the saturation voltage drop of the IGBT, Ic(t) is the collector current of the IGBT, and D is the duty cycle of the IGBT.

[0086] After implementing the above-described solution, this invention can accurately obtain the conduction loss of the IGBT. This conduction loss can be used to calculate the total transient loss. Furthermore, based on the conduction loss of the IGBT, this invention can also determine the overall state of the IGBT based on the proportion of conduction loss, thereby determining whether the IGBT is abnormal. At the same time, during related control, the conduction resistance can be adaptively reduced based on the conduction loss of the IGBT to optimize system efficiency, which helps to achieve better performance and value.

[0087] Furthermore, in order to obtain the switching losses of the IGBT mentioned above, the real-time operating parameters collected in this invention also include: the IGBT bus voltage and the IGBT turn-off time.

[0088] Specifically, the calculation model for the switching loss of IGBT is: Psw(t)=[Vdc*Ic(t)*toff] / 2;

[0089] Where Psw(t) is the switching loss of the IGBT, Vdc is the bus voltage of the IGBT, Ic(t) is the collector current of the IGBT, and tof is the turn-off time of the IGBT.

[0090] After implementing the above-described solution, this invention can accurately obtain the switching loss of the IGBT. This IGBT switching loss can be used to calculate the total transient loss. Furthermore, based on the IGBT switching loss, this invention can also optimize the circuit design parameters and adjust the circuit control strategy to achieve higher operating efficiency. In addition, based on the calculation of switching loss, this invention can also provide corresponding data support for soft-switching technology and reduce the overall loss of the IGBT.

[0091] Please see Figure 3 This is the specific process for calculating the total transient loss in this invention, which collects real-time operating parameters: the saturation voltage drop of the IGBT, the real-time collector current of the IGBT, and the duty cycle of the IGBT.

[0092] After obtaining the above real-time operating parameters, the conduction loss of the IGBT is obtained using the calculation model: Pcond(t)=Vce_sat(t)*Ic(t)*D;

[0093] During the above process, real-time operating parameters are collected simultaneously: IGBT bus voltage, IGBT collector current, and IGBT turn-off time.

[0094] After obtaining the above real-time operating parameters, the switching loss of the IGBT is obtained using the calculation model: Psw(t)=[Vdc*Ic(t)*toff] / 2;

[0095] After obtaining the conduction loss and switching loss of the IGBT through the above steps, the total transient loss of the IGBT can be obtained by using the calculation model: ptot(t)=Pcond(t)+Psw(t).

[0096] In the above calculation process, this invention considers both the conduction loss and the switching loss of the IGBT. The conduction loss is the loss generated when the IGBT is turned on, while the switching loss is the unnecessary energy loss generated when the IGBT is turned on and off. By combining the conduction loss and the switching loss of the IGBT to calculate the total transient loss, this invention can provide a more comprehensive feedback on the loss data of the IGBT throughout the entire operation process. Furthermore, by combining this with the real-time thermal resistance to update the real-time case temperature of the IGBT, the accuracy of the calculation of the real-time junction temperature of the IGBT can be further improved.

[0097] As mentioned above, when calculating the real-time junction temperature of the IGBT in this invention, it is necessary to calculate based on the parameters: real-time case temperature, total transient loss, and real-time thermal resistance. In the technical solution mentioned above, this invention provides a calculation model for the total transient loss, and the real-time case temperature can be obtained by a case temperature sensor installed on the IGBT case. Therefore, in order to calculate the real-time junction temperature of the IGBT, it is also necessary to calculate the real-time thermal resistance of the IGBT. This invention obtains the real-time thermal resistance by adding an update factor based on the reference thermal resistance of the IGBT. Specifically, the calculation model of the real-time thermal resistance of the IGBT in this invention is: Rth_real(t)=Rth_base×[1+a(t)];

[0098] Where Rth_real(t) is the real-time thermal resistance of the IGBT, Rth_base is the reference thermal resistance of the IGBT, and a(t) is the update factor.

[0099] This invention obtains real-time thermal resistance by adding an update factor to the reference thermal resistance of IGBT. Firstly, it solves the problem that thermal resistance increases due to solder voiding while temperature acquisition data remains unchanged. Secondly, it can construct a dynamic thermal resistance compensation mechanism, establish a three-dimensional mapping table of "real-time case temperature, current density, and running time", and correct the thermal resistance coefficient in real time, thus ensuring the accuracy of the calculation of total instantaneous loss.

[0100] The aforementioned update factors can be stored in the DSP and adaptively updated based on historical operating parameters, including: the cumulative operating time of the IGBT, the highest junction temperature cycle count, and the deviation between the real-time case temperature of the IGBT and the theoretical value.

[0101] The above-mentioned update method can be achieved by setting a corresponding learning algorithm in the DSP, allowing the DSP to learn based on historical operating parameters, thereby updating the update factor in real time. This invention uses this update factor to update the thermal resistance of the IGBT in real time, thereby obtaining the real-time thermal resistance. It can construct a dynamic thermal resistance compensation mechanism, establish a three-dimensional mapping table of "real-time case temperature, current density, and operating time", and correct the thermal resistance coefficient in real time to ensure the accuracy of the calculation of total instantaneous loss.

[0102] After obtaining the real-time thermal resistance of the IGBT, the real-time junction temperature of the IGBT can be calculated. Specifically, the calculation model for the real-time junction temperature of the IGBT in this invention is: Tj(t) = Tc(t) + Ptot(t) × Rth_real(t).

[0103] Where Tj(t) is the real-time junction temperature of the IGBT, Tc(t) is the real-time case temperature of the IGBT, Pcond(t) is the conduction loss of the IGBT, and Rth_real(t) is the real-time thermal resistance of the IGBT.

[0104] In the above-described scheme, the present invention calculates the real-time junction temperature of the IGBT using real-time case temperature, total transient loss, and real-time thermal resistance. The calculation process integrates the dual-source coupling of total transient loss and real-time case temperature, as well as the real-time thermal resistance obtained by dynamic compensation of the reference thermal resistance. This can improve the accuracy of the calculation of the real-time junction temperature of the IGBT while ensuring the real-time performance of the acquisition, and reduce the estimation error of the real-time junction temperature of the IGBT.

[0105] Please see Figure 4 The specific process for calculating the real-time junction temperature in this invention involves first collecting real-time operating parameters: the saturation voltage drop of the IGBT, the real-time collector current of the IGBT, and the duty cycle of the IGBT.

[0106] After obtaining the above real-time operating parameters, the conduction loss of the IGBT is obtained using the calculation model: Pcond(t)=Vce_sat(t)*Ic(t)*D;

[0107] During the above process, real-time operating parameters are collected simultaneously: IGBT bus voltage, IGBT collector current, and IGBT turn-off time.

[0108] After obtaining the above real-time operating parameters, the switching loss of the IGBT is obtained using the calculation model: Psw(t)=[Vdc*Ic(t)*toff] / 2;

[0109] After obtaining the conduction loss and switching loss of the IGBT through the above steps, the total transient loss of the IGBT is obtained by using the calculation model: ptot(t)=Pcond(t)+Psw(t).

[0110] While calculating the total transient loss of the IGBT, the DSP learns and updates the update factor through historical operating data, and calculates the real-time thermal resistance based on the update factor.

[0111] After obtaining the total transient loss and real-time thermal resistance through the above steps, the real-time case temperature of the IGBT is collected by a case temperature sensor installed on the IGBT case.

[0112] Finally, the real-time junction temperature of the IGBT is obtained using the calculation model: Tj(t)=Tc(t)+Ptot(t)×Rth_real(t).

[0113] In the above-described scheme, the present invention calculates the real-time junction temperature of the IGBT using real-time case temperature, total transient loss, and real-time thermal resistance. The calculation process integrates the dual-source coupling of total transient loss and real-time case temperature, as well as the real-time thermal resistance obtained by dynamic compensation of the reference thermal resistance. This can improve the accuracy of the calculation of the real-time junction temperature of the IGBT while ensuring the real-time performance of the acquisition, and reduce the estimation error of the real-time junction temperature of the IGBT.

[0114] Furthermore, in this invention, the threshold temperature is configured to be 90% of the highest junction temperature of the IGBT.

[0115] In the original technical solution, the protection strategy for IGBT is to trigger a fuse to turn off the IGBT when the real-time junction temperature of the IGBT reaches the maximum junction temperature, thereby protecting the IGBT. However, based on the threshold temperature setting, this application performs active protection before the real-time junction temperature of the IGBT reaches the maximum junction temperature, thus preventing the IGBT from entering the maximum junction temperature.

[0116] Based on this technical solution, the present invention can transform the original "passive melting" control mechanism into an "active derating" control mechanism before thermal failure. By adjusting the duty cycle of the IGBT in advance, the real-time current of the collector electrode of the IGBT is reduced, thereby achieving active cooling and avoiding catastrophic damage caused by IGBT thermal failure, thus improving the safety and reliability of the system.

[0117] Furthermore, when the real-time junction temperature of the IGBT reaches the aforementioned threshold temperature, the protection strategy implemented by the present invention is as follows: reduce the duty cycle of the IGBT; when the duty cycle of the IGBT is at its lowest, reduce the on-frequency of the IGBT or turn off the IGBT.

[0118] Please see Figure 5 This is the control flowchart for triggering the IGBT protection strategy in this invention. After calculating the real-time junction temperature of the IGBT, it determines whether the real-time case temperature of the IGBT has reached the threshold temperature. If not, it continues to monitor the real-time junction temperature of the IGBT.

[0119] If so, the IGBT protection strategy is triggered, reducing the duty cycle of the IGBT, and at the same time determining whether the duty cycle of the IGBT has been reduced to the minimum duty cycle that can ensure the normal operation of the circuit.

[0120] If not, continue to reduce the duty cycle of the IGBT until the real-time junction temperature of the IGBT is lower than the threshold temperature.

[0121] If not, reduce the IGBT's on-frequency or turn it off.

[0122] This invention clarifies the protection strategy for IGBTs through the above-described scheme. Compared to traditional schemes that protect the IGBT after it has already suffered thermal failure, this invention proactively reduces the IGBT's duty cycle in advance, directly preventing the IGBT's real-time junction temperature from reaching the temperature that would cause thermal failure. This fundamentally eliminates the problem of thermal failure and avoids a series of subsequent control anomalies caused by IGBT thermal failure. Furthermore, if adjusting the duty cycle fails to reduce the IGBT's real-time junction temperature to the threshold temperature, this invention further reduces the IGBT's on-frequency or even directly turns off the IGBT. This process is equivalent to secondary protection, further preventing IGBT thermal failure and ensuring the reliability and safety of the entire system.

[0123] Please see Figure 2 This is the overall control logic of the IGBT thermal failure management method provided by the present invention, and its steps are as follows:

[0124] S1: Data acquisition; that is, acquiring the real-time operating parameters of the IGBT, such as the saturation voltage drop of the IGBT, the real-time collector current of the IGBT, the duty cycle of the IGBT, the bus voltage of the IGBT, the turn-off time of the IGBT, etc.

[0125] S2: Transient power consumption decoupling; that is, the conduction loss and switching loss of the IGBT are decoupled and calculated in the time domain (i.e., calculated through real-time operating parameters), instead of using the effective value averaging method. The total transient loss of the IGBT can be obtained through this step.

[0126] S3: Dynamic thermal resistance correction; that is, the step of correcting the reference thermal resistance of the IGBT by updating the factor to obtain the real-time thermal resistance of the IGBT.

[0127] S4: Real-time junction temperature estimation; that is, calculating the real-time junction temperature of the IGBT using the real-time case temperature, total transient losses, and real-time thermal resistance;

[0128] S5: Thermal trend prediction; that is, to determine whether the real-time junction temperature of the IGBT has reached the threshold temperature. If so, it is determined that there is a risk of junction temperature rise in the IGBT and active cooling of the IGBT is required.

[0129] S6: Multi-level decision-making; that is, the steps to implement IGBT protection strategy, reduce the duty cycle of IGBT, and if the duty cycle has reached the minimum duty cycle, reduce the IGBT's on-frequency or directly turn off the IGBT.

[0130] S7: Output control; that is, controlling the IGBT through the IGBT protection strategy.

[0131] The present invention, through the above-described solution, can achieve the following beneficial effects:

[0132] 1. This invention calculates the real-time junction temperature of IGBT by using real-time case temperature, total transient loss, and real-time thermal resistance. The calculation process integrates the dual-source coupling of total transient loss and real-time case temperature, as well as the real-time thermal resistance obtained by dynamic compensation of the reference thermal resistance. This can improve the accuracy of the calculation of the real-time junction temperature of IGBT while ensuring the real-time performance of the IGBT, and reduce the estimation error of the real-time junction temperature of IGBT.

[0133] 2. By setting the threshold temperature at 90% of the highest junction temperature of the IGBT, this invention can transform the original "passive melting" control mechanism into an "active derating" control mechanism before thermal failure. By adjusting the duty cycle of the IGBT in advance, the real-time current of the collector electrode of the IGBT is reduced, thereby achieving active cooling and avoiding catastrophic damage caused by IGBT thermal failure, thus improving the safety and reliability of the system.

[0134] Based on the above IGBT thermal failure control methods, please refer to Figure 6 The present invention also proposes a voltage regulation circuit, which includes:

[0135] The full-wave rectifier module 10 includes a high-voltage output terminal and a low-voltage output terminal. The full-wave rectifier module 10 is suitable for configuring an input AC signal into a DC signal.

[0136] The power factor correction module 20 is electrically connected to the full-wave rectifier module 10 and includes a first half-bridge assembly, a second half-bridge assembly, and an inductive element disposed between the first half-bridge assembly and the second half-bridge assembly. The first half-bridge assembly is disposed between the low-voltage output terminal and the high-voltage output terminal. The second half-bridge assembly includes multiple power transistors connected in series. One of the multiple power transistors is connected to the first half-bridge assembly. One end of the inductive element is connected to any connection point among the multiple power transistors, and the other end of the inductive element is connected to a designated position of the first half-bridge assembly. The power factor correction module is adapted to configure the DC signal as a bus voltage according to the switch control signal. The bus voltage is boosted or bucked relative to the DC signal. The two ends of the second half-bridge assembly are configured as the output terminals of the bus voltage.

[0137] In the power factor correction module 20, all power transistors are IGBTs, and each IGBT is equipped with a controller. When the controller is working, it executes the IGBT thermal failure management method.

[0138] See further Figure 7 In the above technical solution, the full-wave rectifier module 10 of the present invention includes a transformer with taps, a first power transistor T1 and a second power transistor T2 connected in series. The first power transistor T1 and the second power transistor T2 are disposed between the two coil output terminals of the transformer. One of the connection terminals between the first power transistor T1 and the second power transistor T2 and the tap is configured as the low-voltage output terminal of the full-wave rectifier module, and the other is configured as the high-voltage output terminal.

[0139] In this scheme, the voltage regulation circuit includes a full-wave rectification module 10 and a power factor correction module 20. The full-wave rectification module 10 includes a transformer, a first power transistor T1, and a second power transistor T2. By setting a tap, the transformer has three output terminals. Among them, one of the three output terminals serves as a fixed low-voltage output terminal, while the other two output terminals are connected to the first power transistor T1 and the second power transistor T2, respectively. During the positive half-cycle of the AC signal, the current flows to the high-voltage output terminal through one output terminal and one of the power transistors T1. During the negative half-cycle of the AC signal, the current flows to the high-voltage output terminal through the other output terminal and the other power transistor T2. By combining the switching control of the first power transistor T1 and the second power transistor T2, full-wave rectification can be achieved.

[0140] See further Figure 8 The power factor correction module 20 includes: a third power transistor Q3, a fourth power transistor Q4, a fifth power transistor Q5, a sixth power transistor Q6, an inductive element L, and a capacitive element L;

[0141] In this configuration, the first electrode of the third power transistor Q1 is connected to the high-voltage output terminal DC+, the second electrode of the third power transistor Q1 is connected to the first electrode of the fourth power transistor Q2, and the second electrode of the fourth power transistor Q2 is connected to the low-voltage output terminal DC-. The designated location is the connection point between the third power transistor Q1 and the fourth power transistor Q2. The first electrode of the fifth power transistor Q3 and the second electrode of the sixth power transistor Q4 are configured as the output terminals of the bus voltage. The second electrode of the fifth power transistor Q3 is connected to the first electrode of the sixth power transistor Q4, and the second electrode of the sixth power transistor Q4 is connected to the fourth power transistor Q2.

[0142] In this embodiment, the sixth power transistor Q4 is connected to the low-voltage output terminal, and the fifth power transistor Q3 is not directly connected to either the low-voltage or high-voltage output terminal. One end of the inductive element L is connected between the fifth power transistor Q3 and the sixth power transistor Q4, and the other end of the inductive element L is connected between the third power transistor Q1 and the fourth power transistor Q2. The third power transistor Q1 is connected to the high-voltage output terminal, and the fourth power transistor Q2 is connected to the low-voltage output terminal. This connection method allows the voltage boosting function to be achieved by adjusting the duty cycle of the switch control signal when one of the third power transistor Q1 and the fourth power transistor Q2 is turned off and the other is turned on.

[0143] Furthermore, when one of the fifth power transistor Q3 and the sixth power transistor Q4 is turned off and the other is turned on, the duty cycle of the switch control signal is adjusted, and the switch control signal controls the opening and closing of the third power transistor Q1 and the fourth power transistor Q2 to achieve the boost function.

[0144] Furthermore, by controlling four switching transistors with different switching control signals, a smooth transition is achieved when switching between boost and buck voltage.

[0145] This invention uses IGBTs as the power switching transistors in the above scheme, and configures a corresponding controller to execute the above IGBT thermal failure management method. This can avoid the problem of IGBT thermal failure while ensuring the basic working logic of the voltage regulation circuit, and further ensure the reliability and safety of the voltage regulation circuit.

[0146] Furthermore, the present invention also includes a sampling resistor connected in series in the switching branch of each IGBT, the sampling resistor being used to collect the real-time collector current of the IGBT.

[0147] A thermistor is also installed on the IGBT housing, which is used to collect the real-time housing temperature of the IGBT.

[0148] By setting the sampling resistor as described above, this invention can detect the magnitude of the current in real time, thereby obtaining the real-time collector current of the IGBT for subsequent real-time junction temperature calculation. In addition, based on the setting of the sampling resistor, when an overcurrent problem occurs in the circuit, the voltage on the sampling resistor will rise sharply. By detecting this voltage change, the circuit overcurrent problem can be detected in time, thereby triggering the protection mechanism, avoiding circuit damage, and improving the safety of the entire system.

[0149] Furthermore, by placing the thermistor on the IGBT housing, this invention ensures good heat exchange between the thermistor and the IGBT housing, thereby guaranteeing the accuracy of the real-time housing temperature data acquired by the thermistor and ensuring the accuracy of subsequent calculations of the real-time junction temperature.

[0150] Furthermore, the present invention also proposes an electrical device having the aforementioned voltage regulation circuit.

[0151] This invention, by configuring the aforementioned voltage regulation circuit for electrical equipment, can solve the problem that current power factor correction circuits only have boost or buck functions, which cannot meet the needs of bus voltage regulation and thus result in low operating efficiency.

[0152] Furthermore, the aforementioned electrical equipment can be an air conditioner.

[0153] This invention further expands the aforementioned electrical equipment to air conditioners, which can ensure the operating efficiency of the air conditioning system, meet user needs, and enhance market competitiveness.

[0154] The IGBT thermal failure management method provided by this invention can also be used for failure testing of individual semiconductor devices (such as IGBTs), and belongs to G01R31 / 26 in the strategic emerging industries classification G01R31*.

[0155] Compared with the prior art, the present invention has at least the following beneficial effects:

[0156] 1. This invention calculates the real-time junction temperature of IGBT by using real-time case temperature, total transient loss, and real-time thermal resistance. The calculation process integrates the dual-source coupling of total transient loss and real-time case temperature, as well as the real-time thermal resistance obtained by dynamic compensation of the reference thermal resistance. This can improve the accuracy of the calculation of the real-time junction temperature of IGBT while ensuring the real-time performance of the IGBT, and reduce the estimation error of the real-time junction temperature of IGBT.

[0157] 2. By setting the threshold temperature at 90% of the highest junction temperature of the IGBT, this invention can transform the original "passive melting" control mechanism into an "active derating" control mechanism before thermal failure. By adjusting the duty cycle of the IGBT in advance, the real-time current of the collector electrode of the IGBT is reduced, thereby achieving active cooling and avoiding catastrophic damage caused by IGBT thermal failure, thus improving the safety and reliability of the system.

[0158] It should be noted that the terminology used above is for describing specific embodiments only and is not intended to limit the exemplary embodiments of the present invention. When the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. The order of execution of actions, steps, etc., in the apparatus and methods shown in the specification and drawings may be implemented in any order unless a specific express order is specified, and as long as the output of a previous process is not used in a subsequent process. Similar sequential terms used for ease of description do not imply that such an order must be followed.

[0159] Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as constraints. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0160] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for managing IGBT thermal failure, characterized in that, include: Collect the real-time operating parameters of the IGBT, and calculate the total transient loss of the IGBT based on the real-time operating parameters; Obtain the reference thermal resistance of the IGBT, and calculate the real-time thermal resistance of the IGBT based on the historical operating parameters of the IGBT; The real-time case temperature of the IGBT is collected, and the real-time junction temperature of the IGBT is calculated based on the real-time case temperature, the total transient loss, and the real-time thermal resistance. When the real-time junction temperature of the IGBT reaches the threshold temperature, the IGBT protection strategy is triggered.

2. The IGBT thermal failure management method according to claim 1, characterized in that, The calculation model for the total transient loss of the IGBT is: ptot(t) = Pcond(t) + Psw(t); Where ptot(t) is the total transient loss of the IGBT, Pcond(t) is the conduction loss of the IGBT, and Psw(t) is the switching loss of the IGBT.

3. The IGBT thermal failure management method according to claim 2, characterized in that, The real-time operating parameters include: the saturation voltage drop of the IGBT, the real-time collector current of the IGBT, and the duty cycle of the IGBT; The calculation model for the conduction loss of the IGBT is: Pcond(t) = Vce_sat(t) * Ic(t) * D; Where Pcond(t) is the conduction loss of the IGBT, Vce_sat(t) is the saturation voltage drop of the IGBT, Ic(t) is the collector current of the IGBT, and D is the duty cycle of the IGBT.

4. The IGBT thermal failure management method according to claim 3, characterized in that, The real-time operating parameters also include: the bus voltage of the IGBT and the turn-off time of the IGBT; The calculation model for the switching loss of the IGBT is: Psw(t)=[Vdc*Ic(t)*toff] / 2; Where Psw(t) is the switching loss of the IGBT, Vdc is the bus voltage of the IGBT, Ic(t) is the collector current of the IGBT, and tof is the turn-off time of the IGBT.

5. The IGBT thermal failure management method according to claim 1, characterized in that, The calculation model for the real-time thermal resistance of the IGBT is: Rth_real(t) = Rth_base × [1 + a(t)]; Where Rth_real(t) is the real-time thermal resistance of the IGBT, Rth_base is the reference thermal resistance of the IGBT, and a(t) is the update factor.

6. The IGBT thermal failure management method according to claim 5, characterized in that, The historical operating parameters include: the cumulative operating time of the IGBT, the highest junction temperature cycle number, and the deviation between the real-time case temperature of the IGBT and the theoretical value; The update factor is configured to update adaptively based on the historical running data.

7. The IGBT thermal failure management method according to claim 1, characterized in that, The calculation model for the real-time junction temperature of the IGBT is: Tj(t) = Tc(t) + Ptot(t) × Rth_real(t); Where Tj(t) is the real-time junction temperature of the IGBT, Tc(t) is the real-time case temperature of the IGBT, Pcond(t) is the conduction loss of the IGBT, and Rth_real(t) is the real-time thermal resistance of the IGBT.

8. The IGBT thermal failure management method according to claim 1, characterized in that, The threshold temperature is configured to be 90% of the highest junction temperature of the IGBT.

9. The IGBT thermal failure management method according to claim 1, characterized in that, The IGBT protection strategy includes: reducing the duty cycle of the IGBT; when the duty cycle of the IGBT is at its lowest, reducing the IGBT's on-frequency or turning off the IGBT.

10. A voltage regulation circuit, characterized in that, include: A full-wave rectifier module, including a high-voltage output terminal and a low-voltage output terminal, is adapted to convert an input AC signal into a DC signal; A power factor correction module is electrically connected to the full-wave rectifier module and includes a first half-bridge assembly, a second half-bridge assembly, and an inductive element disposed between the first half-bridge assembly and the second half-bridge assembly. The first half-bridge assembly is disposed between the low-voltage output terminal and the high-voltage output terminal. The second half-bridge assembly includes a plurality of power transistors connected in series. One of the plurality of power transistors is connected to the first half-bridge assembly. One end of the inductive element is connected to any connection point among the plurality of power transistors, and the other end of the inductive element is connected to a designated position of the first half-bridge assembly. The power factor correction module is adapted to configure the DC signal as a bus voltage according to a switch control signal. The bus voltage is boosted or bucked relative to the DC signal. The two ends of the second half-bridge assembly are configured as the output terminals of the bus voltage. The power transistor is an IGBT, and each IGBT is equipped with a controller. When the controller is working, it executes the IGBT thermal failure management method as described in any one of claims 1 to 9.

11. The voltage regulation circuit according to claim 10, characterized in that, A sampling resistor is also connected in series in the switching branch of each IGBT, and the sampling resistor is used to collect the real-time collector current of the IGBT. A thermistor is also provided on the housing of the IGBT, which is used to collect the real-time housing temperature of the IGBT.

12. An electrical appliance, characterized in that, The electrical equipment has a voltage regulation circuit as described in any one of claims 10 to 11.

13. The electrical equipment according to claim 12, characterized in that, The electrical equipment mentioned is an air conditioner.

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