Junction temperature detection method and device for IGBT (Insulated Gate Bipolar Translator) module

Abstract

The invention relates to the technical field of IGBT modules, and discloses a junction temperature detection method and device of an IGBT module. The method comprises the following steps: S1, outputting a PWM (Pulse Width Modulation) driving signal to a grid electrode of an IGBT (Insulated Gate Bipolar Translator) wafer through a single chip microcomputer S2, performing heat conduction sensing on the NTC wafer, connecting the NTC wafer to a T pole pin, and generating a T pole voltage signal with the pull-down resistor; s3, AD conversion is carried out to obtain a T-pole voltage digital quantity, an NTC resistance value of the NTC wafer is calculated according to the T-pole voltage digital quantity, a preset temperature data table is searched, and a current junction temperature value of the IGBT wafer is obtained; and S4, when the current junction temperature value is greater than or equal to the preset protection threshold value, turning off the PWM driving signal, and when the current junction temperature value is smaller than the preset protection threshold value, continuing to output the PWM driving signal and circularly executing the steps S2 to S4. According to the invention, the IGBT module can be effectively protected to work in a reasonable temperature range; and the working reliability and the service life of the IGBT module are improved.

Description

Technical Field

[0001] This invention relates to the field of IGBT module technology, and in particular to a method and apparatus for detecting the junction temperature of an IGBT module. Background Technology

[0002] The temperature rise of power devices is crucial to their safety and lifespan; power devices are the core components that enable the functionality and lifespan of finished products. With rapid economic development, more and more people are using electronic products with numerous power devices, such as air conditioners, microwave ovens, induction cookers, and IH rice cookers. All of these products require power devices, and it is essential to ensure that these devices operate within a suitable temperature range. Overheating of power devices can easily cause damage or even complete failure. Current methods for detecting the temperature of power devices require mounting a finished NTC (Network Temperature Controller) onto the power device's plastic casing. The IGBT junction temperature needs to be conducted through the molding compound to the NTC casing, and then from the NTC casing to the NTC wafer. The NTC wafer's internal resistance changes due to temperature variations, and this change is then transmitted through wires to sampling, filtering, and microcontroller processing. This method cannot directly sample the IGBT junction temperature, nor can it accurately and promptly obtain the data. Furthermore, it is affected by factors such as the mounting process, the contact area between the NTC and IGBT casings, the quality of the IGBT molding compound, and the IGBT molding compound material. To ensure the reliability and lifespan of IGBTs in mass production, it is typically necessary to compensate for and reserve more junction temperature headroom. This also results in high overall costs and complex manufacturing processes, impacting production efficiency.

[0003] Current methods for detecting junction temperature in power devices typically involve mounting an NTC (Network Temperature Detector) sampler on the outside of the IGBT package to measure the package temperature, and then estimating the junction temperature using actual tests on the sample. Because the NTC sampler only detects the temperature of the IGBT's plastic casing, it cannot accurately detect the junction temperature in real time. This necessitates allowing sufficient temperature margin in mass production applications. Consequently, the IGBT often cannot fully utilize its performance, resulting in wasted resources. Summary of the Invention

[0004] The main objective of this invention is to provide a method and apparatus for detecting the junction temperature of an IGBT module. This invention can effectively protect the IGBT module from operating within a reasonable temperature range and improve the reliability and lifespan of the IGBT module.

[0005] To achieve the above objectives, the present invention provides a method for detecting the junction temperature of an IGBT module, comprising the following steps: S1: The microcontroller outputs a PWM drive signal to the gate of the IGBT wafer to turn on the IGBT wafer. S2: Perform thermal conductivity sensing on the NTC wafer that is encapsulated in the same package as the IGBT wafer, and generate a T-terminal voltage signal by connecting the NTC wafer to the T-terminal pin and forming a voltage divider circuit with a pull-down resistor. S3: Perform AD conversion on the T-terminal voltage signal to obtain the digital value of the T-terminal voltage. Calculate the NTC resistance value of the NTC wafer based on the digital value of the T-terminal voltage and look up the preset temperature data table to obtain the current junction temperature value of the IGBT wafer. S4: Compare the current junction temperature value with a preset protection threshold. When the current junction temperature value is greater than or equal to the preset protection threshold, turn off the PWM drive signal. When the current junction temperature value is less than the preset protection threshold, continue to output the PWM drive signal and repeat steps S2 to S4.

[0006] Optionally, in a first implementation of the first aspect of the present invention, step S1 includes: S11: The microcontroller configures the PWM drive signal and transmits it to the gate of the IGBT wafer through the drive resistor; S12: When the PWM drive signal is high, the IGBT wafer is turned on to form a load current loop and generate power loss heat.

[0007] Optionally, in a second implementation of the first aspect of the present invention, step S2 includes: S21: The power loss heat generated by the IGBT wafer is sensed by the NTC wafer encapsulated in the same package as the IGBT wafer; S22: Connect one end of the NTC wafer to the T-pin via a bonding wire, and connect the other end of the NTC wafer to the emitter, forming a voltage divider circuit with the pull-down resistor; S23: Based on the voltage divider circuit, a T-pin voltage signal reflecting the change in NTC resistance value is generated at the T-pin.

[0008] Optionally, in a third implementation of the first aspect of the present invention, step S23 includes: S231: Apply a regulated power supply to the voltage divider circuit formed by the NTC wafer and the pull-down resistor; S232: Based on the change in the NTC resistance value of the NTC wafer in the voltage divider circuit, a corresponding voltage divider voltage is obtained at the T-pin; S233: The voltage divider voltage of the T-pin is filtered by the filter capacitor to obtain the T-pin voltage signal.

[0009] Optionally, in a fourth implementation of the first aspect of the present invention, step S3 includes: S31: The microcontroller's AD converter performs analog-to-digital conversion on the T-pole voltage signal to obtain the digital value of the T-pole voltage; S32: Calculate the NTC resistance value of the NTC wafer based on the digital value of the T-pole voltage, the voltage value of the regulated power supply, and the resistance value of the pull-down resistor; S33: Based on the NTC resistance value, look up the preset temperature data table to obtain the current junction temperature value of the IGBT wafer.

[0010] Optionally, in a fifth implementation of the first aspect of the present invention, step S31 includes: S311: The microcontroller triggers the AD converter to select the analog input channel connected to the T terminal and starts the sample-and-hold circuit. The sampling capacitor of the sample-and-hold circuit charges and samples the voltage signal of the T terminal to obtain the holding voltage value. S312: The AD converter quantizes the holding voltage value and stores it in the data register to obtain the digital value of the T-pole voltage.

[0011] Optionally, in a sixth implementation of the first aspect of the present invention, step S32 includes: S321: Multiply the digital value of the T-pin voltage by the quantization step value to obtain the actual voltage value of the T-pin. S322: Subtract the actual voltage value from the voltage value of the regulated power supply to obtain the voltage divider value on the NTC wafer; S323: Multiply the resistance value of the pull-down resistor by the ratio of the voltage divider value on the NTC wafer to the actual voltage value to obtain the NTC resistance value of the NTC wafer.

[0012] Optionally, in a seventh implementation of the first aspect of the present invention, step S4 includes: S41: The microcontroller reads the preset protection threshold and compares it with the current junction temperature value; S42: When the current junction temperature value is greater than or equal to the preset protection threshold, the microcontroller will force the PWM output pin to be pulled low to 0V to turn off the PWM drive signal; S43: When the current junction temperature is less than the preset protection threshold, the microcontroller maintains the PWM drive signal output and returns to execute steps S2 to S4.

[0013] Optionally, in an eighth implementation of the first aspect of the present invention, step S42 includes: S421: The microcontroller forces the PWM output pin level connected to the drive resistor to 0V, stopping the PWM drive signal output; S422: The driving resistor stops transmitting driving current to the gate of the IGBT wafer, the gate voltage is discharged to 0V through the pull-down path, the IGBT wafer changes from the on state to the off state, and the load current loop is cut off.

[0014] The present invention also provides a junction temperature detection device for an IGBT module, comprising: an IGBT module comprising an NTC wafer and an IGBT wafer, a sampling circuit, a filtering circuit, a microcontroller, and a power supply circuit; the NTC signal terminal of the IGBT module is electrically connected to the sampling circuit, the sampling circuit is electrically connected to the filtering circuit, and the filtering circuit is connected to the microcontroller; the power supply circuit is used to provide operating power.

[0015] In summary, this invention enables rapid and accurate calculation of the real-time junction temperature of the IGBT by encapsulating NTC wafers, fully utilizing the IGBT's performance and significantly improving the performance / function of the finished product. Simultaneously, it effectively protects the IGBT from operating within a reasonable temperature range, improving its reliability and lifespan. This effectively ensures the safety and longevity of the finished product. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the junction temperature detection method for an IGBT module in one embodiment of the present invention; Figure 2 This is a schematic diagram of the internal packaging structure of the IGBT module of the present invention; Figure 3 This is a schematic diagram of the placement scheme of the NTC thermistor wafer in this invention; Figure 4 This is a schematic diagram of the junction temperature detection application circuit of the IGBT module of this invention; Figure 5 This is a schematic diagram of a structural scheme in which the IGBT and the series diode are packaged on two separate wafers. Figure 6 This is a schematic diagram of a single-chip solution that integrates an IGBT and a series diode on the same wafer; Figure 7 This is the first application circuit scheme for IGBT modules with integrated series diodes; Figure 8 This is the second application circuit scheme for IGBT modules with integrated series diodes.

[0017] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the 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 and not intended to limit the invention.

[0019] Reference Figure 1 This embodiment provides a method for detecting the junction temperature of an IGBT module, including the following steps: S1: The microcontroller outputs a PWM drive signal to the gate of the IGBT wafer to turn on the IGBT wafer and make it work. In this embodiment, after the microcontroller completes power-on initialization, its internal control logic loads preset PWM control parameters, including the GPIO mode setting of the output pin, PWM frequency, initial duty cycle, etc. The PWM frequency is set to 20kHz, and the duty cycle is set within the range of 50% to 90% according to the load power requirements. The PWM drive signal configured by the microcontroller is output through the pin and transmitted to the gate of the IGBT wafer via a drive resistor with a fixed resistance value (e.g., 100Ω), causing the gate voltage to gradually rise. When the PWM drive signal enters a high-level state, the drive current is injected into the IGBT gate through the drive resistor, causing the gate voltage to rise above the threshold (e.g., 15V), thereby triggering the IGBT to conduct, forming a low-impedance path between the collector and emitter. The load current flows from the DC bus through the IGBT into the load RL and closes the loop, and the entire load system enters normal operation. During IGBT conduction, there is a certain on-state voltage drop (e.g., 1.5V to 2.5V) inside the chip. The on-state voltage drop and the working current through the load work together to generate conduction power loss. At the same time, there is switching loss due to PWM switching action. These losses will accumulate in the form of heat inside the IGBT wafer and be transferred to the adjacent NTC thermistor wafer through thermal conduction.

[0020] S2: Thermal conduction sensing is performed on the NTC wafer that is packaged in the same package as the IGBT wafer. The voltage signal of the T-terminal is generated by connecting the NTC wafer to the T-terminal pin and forming a voltage divider circuit with the pull-down resistor. In this embodiment, when the IGBT wafer enters the conduction state under the action of the PWM drive signal and starts to work continuously, its internal crystal structure continuously accumulates heat due to the conduction voltage drop and current. The resulting power loss is conducted to the surrounding materials in the form of heat energy. Since the NTC wafer and the IGBT wafer adopt a co-package structure, they are both located in the same package. The physical position of the NTC wafer is close to the heat source area of ​​the IGBT, and it is set within 5 mm of the active heat-generating surface of the IGBT chip. Therefore, the NTC wafer can quickly sense the temperature rise caused by the conduction loss and switching loss of the IGBT through the internal thermal path of the package (such as thermally conductive silicone or direct structural contact), and realize the real-time response to the junction temperature change. One end of the NTC wafer is connected to the T-pin through a metal bonding wire. The T-pin serves as a voltage sampling output terminal and is connected to the analog input channel of the microcontroller through the printed circuit board. At the same time, the other end of the NTC wafer is directly connected to the emitter (E) pin of the IGBT. Thus, in terms of electrical structure, a typical voltage divider circuit is formed in which the NTC is connected in series with the pull-down resistor and the two ends are connected to the 3.3V reference voltage and the ground potential, respectively. In a voltage divider circuit, the resistance of the NTC decreases as the temperature rises, causing a change in the voltage distribution across the resistors in the series circuit. As the NTC resistance gradually decreases, the voltage across it decreases, while the voltage across the pull-down resistor increases. Therefore, the voltage at the connection point between the pull-down resistor and the NTC—that is, the T-pin—will change dynamically with the change in the NTC resistance. The T-pin voltage signal is the electrical reflection of the change in the resistance of the NTC thermistor.

[0021] S3: Perform AD conversion on the T-terminal voltage signal to obtain the digital value of the T-terminal voltage. Calculate the NTC resistance value of the NTC wafer based on the digital value of the T-terminal voltage and look up the preset temperature data table to obtain the current junction temperature value of the IGBT wafer. In this embodiment, after the voltage divider circuit composed of the NTC wafer and pull-down resistors operates stably and outputs an analog voltage signal at the T-pin that is a function of the NTC resistance value, the microcontroller's internal AD converter is configured in timed trigger mode with a sampling period set to 10 milliseconds to continuously track the dynamic changes in the NTC resistance. When the timer reaches the preset period, the AD converter starts the sampling process, selects the analog input channel corresponding to the T-pin, and performs analog-to-digital conversion. The AD converter divides the T-pin voltage into several quantization levels within the range of the regulated power supply (e.g., 3.3V), for example, 4096 levels with 12-bit precision, with each level corresponding to a voltage step value of approximately 0.8 millivolts. After conversion, the digital value of the T-pin voltage output by the AD converter is the integer encoded value corresponding to the current voltage value, reflecting the discrete electrical quantity of the NTC resistance change. The microcontroller uses the series resistor voltage divider formula to back-calculate the current NTC resistance value based on the digital value of the T-pin voltage, the output voltage value of the regulated power supply, and the resistance value of the pull-down resistor. That is, according to the formula R...NTC = R1 (V cc -V T ) / V T Calculate the actual resistance value of the NTC thermistor, where R1 is the nominal resistance value of the pull-down resistor, V. cc It is the regulated power supply voltage, V T This is the T-terminal voltage value. The microcontroller uses the NTC resistor value as a lookup index to retrieve the factory-preset NTC temperature-resistance mapping table from the Flash memory. The lookup table stores multiple temperature points from 25℃ to 150℃ and their corresponding NTC resistor values. If the current resistance value corresponds exactly to a certain temperature node, its corresponding temperature is directly read as the current junction temperature of the IGBT; if the current resistance value is between two temperature points, a linear interpolation operation is performed to obtain an estimated temperature value.

[0022] S4: Compare the current junction temperature value with the preset protection threshold. When the current junction temperature value is greater than or equal to the preset protection threshold, turn off the PWM drive signal. When the current junction temperature value is less than the preset protection threshold, continue to output the PWM drive signal and cycle through steps S2 to S4.

[0023] In this embodiment, the microcontroller reads the factory-preset temperature protection threshold from the internal Flash memory. The temperature protection threshold is set to 135°C, serving as a boundary benchmark for determining whether the IGBT is at risk of overheating. A comparison algorithm is invoked to compare the current junction temperature with the temperature protection threshold, and different control paths are entered based on the comparison result. When the comparison result indicates that the current junction temperature is greater than or equal to the preset protection threshold, the microcontroller considers the IGBT to be in a thermal danger state and executes a protection action. Specifically, the GPIO control logic forces the pin used to output the PWM signal to a low level (0V), thereby turning off the PWM drive output. Since the PWM drive signal is turned off, the IGBT gate no longer receives drive current, and its gate voltage is quickly discharged to zero volts through the pull-down resistor. The IGBT quickly switches from the on state to the off state, the load current is cut off, and the chip power consumption is minimized, achieving active thermal protection shutdown. Conversely, when the comparison result indicates that the current junction temperature is lower than the preset protection threshold, it means that the IGBT is currently operating within a safe temperature range. The microcontroller will maintain the continuous output of the PWM signal, keeping the IGBT on while continuing to maintain normal load operation. The system control flow returns and repeats the temperature monitoring cycle that started from step S2, re-sensing the NTC temperature change, acquiring the T-terminal voltage, performing AD conversion, updating the current junction temperature, and performing protection judgment again. This cycle repeats continuously to achieve real-time monitoring and dynamic protection of the IGBT junction temperature.

[0024] In one example, step S1 includes: S11: The microcontroller configures the PWM drive signal and transmits it to the gate of the IGBT wafer through the drive resistor; S12: When the PWM drive signal is high, the IGBT wafer is turned on to form a load current loop and generate power loss heat.

[0025] In this example, during the microcontroller initialization phase, the PWM output pin used to control the IGBT is configured. The PWM output pin is set to push-pull output mode and bound to the internal timer module to generate a PWM signal with a set frequency and duty cycle. The PWM frequency is set between 20kHz and 40kHz to balance response speed and EMI suppression capability, while the initial duty cycle is dynamically set according to the required load power, for example, a range of 40% to 90%. After the microcontroller initialization is complete, its timer periodically outputs alternating high and low level PWM pulse signals according to the preset configuration. The PWM pulse signals are transmitted through the GPIO pin to the circuit path connected to the IGBT gate. A drive resistor is connected in series in the circuit path. The drive resistor is a surface-mount resistor with a resistance of tens to hundreds of ohms. Its function is to limit the impact of the microcontroller's output current, avoid gate voltage spikes caused by excessively fast charging or damage to the microcontroller pins due to reverse induced current, and suppress oscillations caused by high-frequency noise. When the PWM drive signal is high, the microcontroller output pin is pulled high to 3.3V or 5V, injecting current into the IGBT gate through the drive resistor. Since the gate is equivalent to a capacitor, the injected current causes the gate voltage to rise within a certain time. When the gate voltage exceeds the IGBT's turn-on threshold voltage (e.g., 10V to 15V), electron tunneling occurs in the metal-oxide structure inside the IGBT wafer, forming a low-impedance channel between the collector and emitter, triggering the IGBT to turn on. At this time, the external power supply is input through the collector, and the current flows from the IGBT's conduction channel to the emitter, ultimately forming a complete operating current loop through the load RL. The load begins to operate normally, and the system enters a steady-state operating state. During this process, the IGBT wafer has low impedance characteristics, but there is still a certain on-state voltage drop, for example, it can reach 1.5V to 2.5V under high current conditions. Simultaneously, because the PWM signal continuously switches between on and off states, the IGBT needs to experience a certain transition time at each turn-on and turn-off moment, resulting in switching losses during the edge period. Therefore, while the IGBT is conducting and handling the load current, its internal wafer continuously accumulates heat due to the on-state voltage drop and power loss during the switching process, resulting in a junction temperature rise. This heat consists of two parts: conduction loss and switching loss. The conduction loss is proportional to the load current, while the switching loss is related to parameters such as PWM frequency, rise time, and fall time. This heat released from inside the IGBT wafer is quickly conducted to the adjacent NTC wafer through the packaging structure.

[0026] In one example, step S2 includes: S21: Sensing the power loss heat generated by the IGBT wafer through the NTC wafer encapsulated in the same package as the IGBT wafer; S22: Connect one end of the NTC wafer to the T pin via a bonding wire, and connect the other end of the NTC wafer to the emitter, forming a voltage divider circuit with the pull-down resistor; S23: Based on the voltage divider circuit, a voltage signal is generated at the T-pin that reflects the change in the NTC resistance value.

[0027] In this example, the NTC thermistor wafer and the IGBT power wafer are co-packaged in the same plastic package module. The NTC wafer is placed on the package pads close to the heat-generating core area of ​​the IGBT, with a physical distance of no more than 5mm. This allows the NTC to quickly respond to the junction temperature changes of the IGBT wafer during operation through close-range heat conduction. When the IGBT is turned on under the action of the PWM drive signal and supplies power to the load, the power loss generated by the on-state voltage drop and the switching process is converted into heat that accumulates inside the wafer. The heat is rapidly transferred to the NTC wafer attached to the side via the packaging medium between the chip and the substrate, causing the NTC temperature to rise synchronously. Since the NTC is a negative temperature coefficient thermistor, its resistance decreases as the temperature rises. Therefore, its resistance change directly reflects the current thermal state of the IGBT. During packaging, one end of the NTC wafer is connected to the T-pin via a gold wire, and the other end is directly connected to the emitter pin of the IGBT, thus forming a typical voltage divider circuit outside the system consisting of the NTC and a pull-down resistor in series. In the voltage divider structure, the NTC is connected in series with a 10kΩ pull-down resistor R1. One end is connected to the positive terminal of a 3.3V regulated power supply, and the other end is connected to ground. The T-pin, as the connection point between the NTC and the pull-down resistor, is located at the midpoint of the circuit, and its potential is directly affected by changes in the NTC's resistance. As the NTC's resistance decreases due to temperature, the voltage originally distributed across the NTC decreases, and the voltage carried by the pull-down resistor R1 increases accordingly, thus the T-pin voltage gradually increases. Conversely, if the temperature decreases and the NTC's resistance rises again, the T-pin voltage decreases accordingly. Therefore, the voltage signal on the T-pin becomes the electrical expression of the NTC's thermal response process. The voltage signal is stably output to the microcontroller's analog sampling channel.

[0028] Step S21 includes: S211: The NTC wafer and the IGBT wafer are packaged in the same package, with the NTC wafer placed on a pad adjacent to the IGBT wafer, and the physical distance between them is less than 5mm; S212: The power loss heat generated by the IGBT wafer during operation is conducted to the NTC wafer through the internal heat conduction path of the package; S213: After receiving the power loss heat, the temperature of the NTC wafer rises, and the resistance value of the NTC wafer decreases as the temperature rises, with a temperature response time of less than 100ms; S214: The change in the resistance value of the NTC wafer reflects the junction temperature change of the IGBT wafer in real time, eliminating the temperature hysteresis phenomenon caused by the thermal resistance of the package in traditional external sensor solutions.

[0029] In one example, step S23 includes: S231: Applying regulated power to the voltage divider circuit formed by the NTC wafer and pull-down resistor; S232: Based on the change in the NTC resistance value of the NTC wafer in the voltage divider circuit, the corresponding voltage divider voltage is obtained at the T terminal pin; S233: The voltage divider voltage of the T-pin is filtered by the filter capacitor to obtain the T-pin voltage signal.

[0030] In this example, a stable reference voltage source is introduced externally to the IGBT module. This reference voltage source is generated by an LDO or voltage reference circuit, with a typical output voltage of 3.3V, supplying the high-potential end of the voltage divider circuit. One end of the reference voltage is connected to the top of the NTC wafer, and the other end is connected to system ground, forming a closed-loop voltage output path. The bottom of the NTC wafer is electrically connected to the emitter pin of the IGBT module and is connected in series with a 10kΩ pull-down resistor R1 via a PCB trace. The other end of R1 is grounded, thus forming a series voltage divider circuit between the NTC and R1, creating a stable voltage drop across them. In this circuit, the resistance of the NTC monotonically decreases as the temperature rises, therefore the voltage it receives in the voltage divider circuit also changes accordingly. Specifically, the NTC voltage gradually decreases, while the voltage across the pull-down resistor R1 increases, ultimately forming a dynamically fluctuating voltage divider at the connection point—the T-pin—that changes with the NTC resistance. As the junction temperature rises, the NTC resistance decreases from 50kΩ to 10kΩ or lower, and correspondingly, the T-terminal voltage gradually increases from 0.5V to over 2V. This voltage change directly reflects the current thermal state. Because the IGBT frequently switches between on and off in high-frequency PWM drive mode, high-frequency spikes, common-mode interference, and electromagnetic interference are easily generated in the circuit. To avoid sampling errors introduced by transient interference, a filter capacitor C1 with a capacitance between tens and hundreds of nanofarads is connected in parallel between the T-terminal pin and ground. The connection of C1 forms a low-pass filter network from the T-terminal node to ground, which smooths the T-terminal voltage divider, weakens high-frequency components, suppresses switching noise, and outputs a stable, continuous, and sampleable T-terminal voltage signal.

[0031] Step S233 includes: S2331: One end of the filter capacitor is connected to the T-pin, and the other end is connected to ground, forming an RC low-pass filter circuit in parallel with the pull-down resistor; S2332: When the IGBT wafer switches between on and off under the action of the PWM drive signal, the T-pin generates a switching transient voltage spike with a frequency higher than 20kHz; S2333: The RC low-pass filter circuit attenuates the switching transient voltage spike by charging and discharging, filtering out high-frequency interference components higher than the cutoff frequency; S2334: The smoothed voltage divider output by the RC low-pass filter circuit is used as the T-pin voltage signal, and the peak-to-peak ripple of the T-pin voltage signal is less than 50mV.

[0032] In one example, step S3 includes: S31: The microcontroller's AD converter performs analog-to-digital conversion on the T-pole voltage signal to obtain the digital value of the T-pole voltage; S32: Calculate the NTC resistance value of the NTC wafer based on the digital value of the T-terminal voltage, the voltage value of the regulated power supply, and the resistance value of the pull-down resistor. S33: Find the preset temperature data table based on the NTC resistance value to obtain the current junction temperature value of the IGBT wafer.

[0033] In this example, when the NTC wafer senses the heat generated by the IGBT wafer within its package and changes its resistance accordingly, the series voltage divider circuit formed by the NTC wafer and pull-down resistor R1 generates a voltage signal reflecting the temperature change at the T-pin. This voltage signal is smoothed by filter capacitor C1 and then input to the analog input pin connected to the microcontroller's internal ADC module. At this time, the microcontroller's timer triggers the ADC to begin an analog-to-digital conversion process according to a preset period. The sample-and-hold circuit locks the instantaneous value of the T-pin voltage and then performs 12-bit quantization using a successive approximation method. Under a 3.3V regulated power supply, the input analog voltage is divided into 4096 levels, each with a step value of 0.8 millivolts. Therefore, different T-pin voltages correspond to a unique ADC digital value. For example, when the T-pin voltage is 0.8V, the conversion result is 1000; when the voltage is 2.4V, the conversion result is 3000. This digital value is the T-pin voltage digital value. The microcontroller program uses the digital value of the T-terminal voltage to reconstruct the actual T-terminal voltage value, which is obtained by multiplying the digital value by 0.8 mV to get the analog voltage value. Then, it calculates the current resistance value of the NTC wafer using the formula for a series voltage divider circuit. Since the regulated power supply voltage in the circuit is a known constant (e.g., 3.3V), the resistance of the pull-down resistor R1 is 10kΩ, and the T-terminal voltage is the calculated analog value, the resistance value can be calculated using the formula R... NTC = R1 (V cc -V T ) / V T Calculate the equivalent resistance of the NTC, where R1 is the nominal resistance of the pull-down resistor, V. cc It is the regulated power supply voltage, V T This refers to the transistor's junction voltage (T). For example, when the T-terminal voltage is 2.2V, the NTC resistance is approximately 5kΩ; when the voltage is 0.55V, the NTC resistance is approximately 50kΩ. After calculating the resistance value, the microcontroller accesses the pre-stored NTC temperature-resistance lookup table in Flash memory. This lookup table is generated based on the NTC device's factory characteristic curve and covers a temperature range from 25℃ to 150℃. If the calculated NTC resistance value corresponds exactly to a node in the table, the current temperature is directly extracted as the current junction temperature of the IGBT wafer. If the resistance value falls between two temperature nodes, the program uses a linear interpolation algorithm to calculate the corresponding intermediate temperature point based on the resistance and temperature values ​​of two adjacent nodes as the estimation result.

[0034] Step S33 includes: S331: The microcontroller reads a preset temperature data table from the Flash memory. The preset temperature data table contains multiple sets of discrete temperature points and their corresponding NTC resistance values; S332: The NTC resistance value of the NTC wafer is compared with each set of NTC resistance values ​​in the preset temperature data table one by one, and two adjacent calibration points are found that satisfy the condition that the resistance value of the i-th set is less than or equal to the NTC resistance value and the resistance value of the (i+1)-th set is greater than the NTC resistance value; S333: The temperature value Ti corresponding to the i-th set of calibration points and the temperature value Ti+1 corresponding to the (i+1)-th set of calibration points are read, the temperature difference is calculated as Ti+1 minus Ti, and the resistance difference is calculated as the resistance value of the (i+1)-th set minus the i-th set of resistance values; S334: The resistance offset is obtained by subtracting the i-th set of resistance value from the NTC resistance value of the NTC wafer, and the temperature offset is obtained by multiplying the temperature difference by the ratio of the resistance offset to the resistance difference; S335: The temperature offset is added to the temperature value Ti to obtain the current junction temperature value of the IGBT wafer.

[0035] In one example, step S31 includes: S311: The microcontroller triggers the AD converter to select the analog input channel connected to the T terminal and starts the sample-and-hold circuit. The sampling capacitor of the sample-and-hold circuit charges and samples the voltage signal at the T terminal to obtain the holding voltage value. S312: The AD converter quantizes the voltage value and stores it in the data register to obtain the digital value of the T-pole voltage.

[0036] In this example, the operating parameters of the ADC module are configured in the microcontroller system, including input channel selection, reference voltage setting, quantization accuracy, and sampling trigger mode. The microcontroller pre-configures the analog channel where the T-pin is located as the ADC input source and sets the reference voltage to 3.3V, consistent with the system's regulated power supply. The ADC conversion accuracy is set to 12 bits, dividing the input voltage range into 4096 quantization levels, with each level's voltage step being 3.3V divided by 4096, approximately 0.8 millivolts. When the system timer reaches the sampling period trigger point, the microcontroller issues a command to start the ADC conversion, controlling the internal analog selection switch of the ADC module to select the analog input channel corresponding to the T-pin and activating the sample-and-hold circuit. The sampling capacitor in the sample-and-hold circuit begins to rapidly charge the T-pin voltage; this charge accumulation process is completed in a very short time. Finally, the voltage value of the sampling capacitor stabilizes at the same level as the T-pin voltage; this voltage value is the holding voltage and serves as the instantaneous representation of the current analog voltage signal. After stabilizing the voltage, the successive approximation converter of the ADC module begins to compare the ratio of the holding voltage to the reference voltage bit by bit, performing the approximation judgment in order from the most significant bit to the least significant bit. It controls the DAC to generate progressively approximate voltages and compares them with the holding voltage to determine the numerical state of each bit. The conversion process requires 12 clock cycles, and upon completion, an integer value between 0 and 4095 is obtained, representing the ratio of the sampled voltage to the full-scale voltage of 3.3V. This value is stored in the ADC's data register, which is the digital value of the T-pole voltage.

[0037] Step S312 includes: S3121: The microcontroller configures the AD converter to perform 16 analog-to-digital conversions consecutively within a single trigger cycle, with an interval of 100 microseconds between each conversion; S3122: The 16 conversion results obtained from the 16 consecutive analog-to-digital conversions are summed to obtain the total accumulated digital value; S3123: The total accumulated digital value is divided by 16 to obtain the arithmetic average of the T-pole voltage digital value; S3124: The arithmetic average of the T-pole voltage digital value is stored in the data register as the T-pole voltage digital value for the current sampling cycle.

[0038] In one example, step S32 includes: S321: Multiply the digital value of the T-terminal voltage by the quantization step value to obtain the actual voltage value of the T-terminal pin; S322: Subtract the actual voltage value from the voltage value of the regulated power supply to obtain the voltage divider value on the NTC wafer; S323: Multiply the pull-down resistor value by the ratio of the voltage divider value on the NTC wafer to the actual voltage value to obtain the NTC resistance value of the NTC wafer.

[0039] In this example, the microcontroller calculates the actual voltage value of the T-pin by multiplying the digital value of the T-pin voltage by the quantization step value of the ADC. For example, under the condition of using 3.3V as the reference voltage and 12-bit precision ADC, the quantization step value is 3.3V ÷ 4096, which is approximately equal to 0.0008V, or 0.8 millivolts. Therefore, if the digital value of the T-pin voltage is 2500, the actual voltage value is 2500 × 0.0008V = 2.0V. Subtracting the current actual voltage value from the reference voltage value of the regulated power supply yields the voltage drop applied across the NTC wafer, which is the voltage division borne by the NTC. For example, if the reference voltage is 3.3V and the T-pin voltage is 2.0V, the voltage across the NTC is 1.3V, reflecting the voltage environment of the NTC in the voltage divider circuit. Based on the voltage divider principle of resistor series, the NTC and pull-down resistor R1 form a series circuit with the same current. Therefore, the resistance ratio between NTC and R1 is equal to the ratio of their voltages. Thus, multiplying the resistance of R1 by the ratio of the NTC voltage to the R1 voltage allows us to deduce the NTC resistance value using the formula R... NTC = R1 (V NTC / V T ) is calculated, where V NTC = V cc -V T R1 is the fixed resistance value of the pull-down resistor, V T This is the voltage at the T-pole.

[0040] Step S323 includes: S3231: The microcontroller reads the measured resistance value and temperature coefficient of the pull-down resistor at 25℃ pre-stored in the Flash memory; S3232: The microcontroller obtains the current ambient temperature value of the PCB board and subtracts 25℃ from the current ambient temperature value of the PCB board to obtain the temperature difference value; S3233: The temperature coefficient is multiplied by the temperature difference value to obtain the resistance correction coefficient, and the measured resistance value of the pull-down resistor at 25℃ is multiplied by the resistance correction coefficient to obtain the temperature-compensated pull-down resistor value; S3234: The temperature-compensated pull-down resistor value is multiplied by the ratio of the voltage divider value on the NTC wafer to the actual voltage value to obtain the NTC resistance value of the NTC wafer.

[0041] In one example, step S4 includes: S41: The microcontroller reads the preset protection threshold and compares it with the current junction temperature value; S42: When the current junction temperature is greater than or equal to the preset protection threshold, the microcontroller will force the PWM output pin to be pulled low to 0V to turn off the PWM drive signal. S43: When the current junction temperature is less than the preset protection threshold, the microcontroller maintains the PWM drive signal output and returns to execute steps S2 to S4.

[0042] In this example, during the microcontroller's initialization phase, a preset junction temperature protection threshold is written to the Flash non-volatile memory or configured online into the system variables. The protection threshold is set to 135 degrees Celsius, serving as a baseline limit for determining whether the IGBT is on the verge of thermal runaway. Once the system completes NTC resistor sampling, table lookup, and calculation of the current IGBT junction temperature during operation, the preset protection threshold is read from the Flash memory and compared with the real-time junction temperature value. The microcontroller's internal program inputs two temperature variables into the comparison logic module. A conditional branch statement checks if the current junction temperature is greater than or equal to the set protection threshold. If the result is true, the microcontroller's internal control logic sets the PWM output pin, originally driven by a timer, to a low logic level. Simultaneously, it forcibly shuts down the PWM timer module and clears the duty cycle register, keeping the output level continuously at 0V. This prevents the IGBT gate connected to this pin from receiving drive current, causing its gate voltage to rapidly drop below the threshold. This forces the IGBT to switch from the on state to the off state, interrupting the load current, eliminating internal power loss, and stopping chip heating. This effectively prevents serious faults such as device breakdown and thermal burnout caused by excessive junction temperature. If the current junction temperature is still below the protection threshold, the microcontroller maintains the original PWM drive output state, keeping the IGBT on and ensuring continuous power supply and normal operation of the load circuit. While maintaining the output, the program control flow returns and re-executes the NTC sampling, AD conversion, and temperature calculation process that started in step S2, achieving continuous cyclic monitoring of the IGBT module junction temperature.

[0043] In one example, step S42 includes: S421: The microcontroller forces the PWM output pin level connected to the drive resistor to 0V, stopping the PWM drive signal output; S422: The drive resistor stops transmitting drive current to the gate of the IGBT wafer, the gate voltage is discharged to 0V through the pull-down path, the IGBT wafer changes from the on state to the off state, and the load current loop is cut off.

[0044] In this example, when the microcontroller confirms that the current junction temperature has reached or exceeded the preset thermal protection threshold through NTC resistor sampling and temperature lookup logic, its internal control flow executes a protection strategy. This forces the GPIO pin corresponding to the PWM signal output channel to be pulled low to 0V, stopping the PWM timer's output function. Furthermore, by directly writing to the control register, the pin level is continuously kept low, regardless of the original PWM duty cycle. The system then enters a forced output shutdown mode, completely blocking the periodic modulation signal of the drive voltage. Simultaneously, since this pin is connected to the IGBT wafer gate through a drive resistor, the voltage difference across the drive resistor becomes zero after the PWM output pin level is pulled low, current stops flowing, and the IGBT gate loses the charge injection source required to maintain its on-state. Entering the S422 stage, the gate itself retains a certain charge due to its capacitive characteristics. However, with the PWM output pin at a low level, the gate charge is gradually released through the pull-down resistor connected in parallel between the gate and ground or the internal discharge path. The voltage rapidly drops below the IGBT turn-on threshold. When the gate voltage drops below the threshold, the channel structure inside the wafer is shut off, and the collector and emitter transition from a low-resistance state to a high-resistance state. The IGBT enters the off state, thereby cutting off the main current path in the load circuit and interrupting the RL load that was originally powered by the circuit. During this process, not only is the IGBT power loss immediately reduced to a minimum, but also, due to the extremely low leakage current in the off state, the entire module enters a low-power safety protection state, effectively avoiding the risk of chip overheating and damage.

[0045] The process includes the following steps after step S422: S423: After the microcontroller turns off the PWM drive signal, it continues to cycle through steps S2 to S3, continuously monitoring the current junction temperature of the IGBT wafer; S424: The microcontroller reads a preset recovery temperature threshold and compares the continuously monitored current junction temperature with the preset recovery temperature threshold; S425: When the current junction temperature is greater than or equal to the preset recovery temperature threshold, the microcontroller maintains the PWM drive signal off state and continues to execute step S423; S426: When the current junction temperature is less than the preset recovery temperature threshold, the microcontroller automatically reconfigures and outputs the PWM drive signal to the gate of the IGBT wafer, so that the IGBT wafer returns to the on-state.

[0046] This embodiment provides a junction temperature detection device for an IGBT module, including: The system comprises an IGBT module with encapsulated NTC and IGBT wafers, a sampling circuit, a filtering circuit, a microcontroller, and a power supply circuit. The NTC signal terminal of the IGBT module is electrically connected to the sampling circuit, which in turn is electrically connected to the filtering circuit. The filtering circuit is connected to the microcontroller. The power supply circuit provides operating power to the system. Specifically, the junction temperature is detected in real-time by the NTC wafer encapsulated within the IGBT module, which senses the junction temperature of the IGBT wafer. The resistance of the NTC wafer decreases as the junction temperature of the IGBT wafer rises. The signal terminal of the NTC wafer is electrically connected to the sampling and filtering circuits to sample the IGBT wafer junction temperature signal. The sampled junction temperature signal is transmitted to the microcontroller, which converts, analyzes, judges, and calculates the IGBT junction temperature and stores this data for use in other control strategies. The IGBT module includes: an IGBT wafer, an NTC wafer, a packaging frame, gold wires, molding compound, and the NTC wafer is located near the gold wires leading out from the emitter (E) terminal of the IGBT wafer. The key feature is that one end of the NTC wafer is electrically connected to the emitter (E) terminal of the IGBT wafer, and the other end of the NTC wafer is electrically connected to the fourth pin of the package frame. The NTC wafer is used to detect the temperature signal of the IGBT wafer. The sampling circuit includes a voltage divider resistor R1 connected in series with the NTC inside the IGBT wafer, and the other end of the voltage divider resistor R1 is connected to a reference voltage. The filtering circuit includes a filter capacitor C1 connected in parallel with the NTC inside the IGBT wafer, and the filter capacitor is used to filter out interference signals on the NTC wafer. The microcontroller includes an ADC module, a storage module, a computing module, and control algorithm software. The power supply circuit includes a high voltage for the IGBT module, a reference voltage for the sampling circuit, and a power supply for the microcontroller.

[0047] like Figure 2 As shown, Figure 2 This is a schematic diagram of the internal packaging structure of the IGBT module of the present invention, including the internal structural components and pin configuration of the package. The package contains two independent wafer chips: an IGBT wafer and an NTC wafer. The IGBT wafer is located at the center of the package, and its gate, collector, and emitter are connected to three pin pads on the bottom of the package via metal bonding wires. The NTC wafer is located to the right of the IGBT wafer, maintaining a distance of less than 5mm from the IGBT wafer to achieve rapid heat conduction. Four external pins are located on the bottom of the package, from left to right: G (gate pin, used to receive PWM drive signals), C (collector pin, connected to the load power supply), E (emitter pin, connected to ground potential), and T (temperature sensing pin, leading out the NTC thermistor signal). One end of the NTC wafer is connected to the E pin via a pad, and the other end is connected to the T pin via a metal bonding wire, forming a temperature sensing signal path.

[0048] like Figure 3 As shown, Figure 3This is a schematic diagram of the placement scheme for the NTC thermistor wafer in this invention, including four external pins P1, P2, P3, and P4, corresponding to the gate (G), collector (C), emitter (E), and transmitter (T) terminals, respectively. Inside the package, metal bonding wires connect the three electrodes of the IGBT wafer to their respective pads.

[0049] In this embodiment, the NTC wafer body can be placed on the P3 pad, which corresponds to the emitter (E) pin. One end of the NTC wafer is directly electrically connected to the P3 pad (physical contact forming an ohmic contact), and the other end is connected to the P4 pad (corresponding to the transmitter (T) pin) via a gold wire bonding wire. In this scheme, the NTC wafer is grounded through the emitter pin and signals are led out through the transmitter (T) pin.

[0050] In this embodiment, the NTC wafer body can also be placed on the P4 pad, which corresponds to the T-pin. One end of the NTC wafer is directly electrically connected to the P4 pad, and the other end is connected to the P3 pad (corresponding to the E-pin) via a gold wire bonding wire. In this scheme, the NTC wafer is connected through the T-pin at one end and grounded through the E-pin at the other end.

[0051] The two schemes are equivalent in electrical connection, both connecting the two ends of the NTC to the E and T terminals respectively. The only difference is the physical placement of the wafer and the direction of the bonding wire connection.

[0052] like Figure 4 As shown, Figure 4This is a schematic diagram of the junction temperature detection application circuit for the IGBT module of this invention. It includes a microcontroller: as the control core, its PWM output pin is connected to the gate (G) of the IGBT via a drive resistor R2, used to output a PWM drive signal to control the IGBT's conduction and cutoff. The microcontroller's AD sampling pin is connected to the emitter (E) of the IGBT (via a pull-down resistor R1 and a filter capacitor C1 node), used to acquire the voltage signal at the transistor (T) terminal. The microcontroller's ground pin is connected to the circuit ground. Drive resistor R2: connected between the microcontroller's PWM output pin and the IGBT gate, used to limit the gate drive current and protect the microcontroller's GPIO pins. IGBT: The gate (G) is connected to the drive resistor R2 to receive the drive signal; the collector (C) is connected to one end of the load RL; the emitter (E) is connected to the common node of the pull-down resistor R1 and the filter capacitor C1 and then grounded; the transistor (T) (temperature sensing electrode) leads out an NTC signal connected to the common node of R1 and C1. Load RL: one end is connected to the positive power supply, and the other end is connected to the collector (C) of the IGBT, forming the IGBT's load circuit. Pull-down resistor R1: 10kΩ, one end connected to the T pin (the common node between the E pin and the microcontroller's AD sampling pin), the other end grounded, forming a series voltage divider circuit with the NTC thermistor inside the IGBT. Filter capacitor C1: 100nF, connected in parallel across R1, used to filter out high-frequency noise on the T pin and voltage spikes generated during IGBT switching.

[0053] Working principle: The microcontroller outputs a PWM drive signal to the IGBT gate via R2 to turn on the IGBT. The load current flows from the positive terminal of the power supply through RL, the collector (C) of the IGBT, to the emitter (E) and then to ground. The IGBT conduction causes power loss, leading to an increase in junction temperature. The NTC thermistor senses the temperature change, causing a change in resistance, which forms a voltage divider across R1. This voltage signal is fed back to the microcontroller's AD sampling pin through the T pin. The microcontroller calculates the junction temperature based on the sampled voltage and executes protection control.

[0054] like Figure 5 As shown, Figure 5 This diagram illustrates a structural design using two independent wafer packages for the IGBT and series diodes. The focus of this design is on integrating the protection diode. Package structure components: IGBT wafer: Located on the left side of the package, its gate, collector, and emitter are connected to the G, C, and E pin pads via bonding wires, respectively. Diode wafer: Located on the right side of the package, it is an independent wafer chip containing n diode units (n>3), connected in series in a forward direction using multiple diodes D1, D2, D3...Dn. Pin configuration: There are four external pins on the bottom of the package, from left to right: G, C, E, and A (or K).

[0055] In this embodiment, a diode wafer can be composed of n diodes (n>3), connected in series in a forward direction. The anode (A) of the series chain is connected to the A-pin via a bonding wire, and the cathode is connected to the E-pin via a bonding wire, electrically connected to the emitter of the IGBT. In this configuration, the current direction of the diode series chain is from the A-pin to the E-pin. The series diodes provide overvoltage protection or freewheeling function. n diodes connected in series can achieve n times the forward conduction voltage threshold of a single diode, used for voltage clamping protection.

[0056] In this embodiment, a diode wafer can also be used to contain n diodes (n>3), which are connected in series in a forward direction. The anode of the series chain is connected to the emitter (E) pin via a bonding wire, and the cathode (K) pin is connected to the base (K) pin via a bonding wire. In this configuration, the pin is labeled K instead of A. The series diodes provide overvoltage protection or freewheeling function. Connecting n diodes in series provides n times the forward conduction voltage threshold of a single diode, which is used for voltage clamping protection.

[0057] like Figure 6 As shown, Figure 6 This diagram illustrates a single-chip solution integrating an IGBT and a series diode on the same wafer, employing single-wafer integration: the IGBT and diode are integrated onto the same silicon wafer using semiconductor processes. The dashed lines in the diagram represent the IGBT and diode regions, formed separately on the same substrate through photolithography, diffusion, and other processes. The IGBT occupies the main area of ​​the wafer, while the diode region forms n series-connected diode units through a specific PN junction structure. Pin configuration: the bottom four pins are the gate (G), collector (C), emitter (E), and anode (A) (or k-pin).

[0058] In this embodiment, a diode wafer can be used to contain n diodes (n>3). The n diodes are connected in series in the middle of the wafer through a metal interconnect layer. The anode of the series chain is connected to the A-pin through metal wiring and bonding wire, and the cathode is connected to the E-region through metal wiring and electrically connected to the emitter of the IGBT.

[0059] In this embodiment, the anode of the series chain can be connected to the E region, and the cathode (K) can be led out to the K pin through a bonding wire.

[0060] The single-wafer integration solution in this embodiment reduces the package size, lowers parasitic inductance, and improves reliability, but it also has higher process complexity.

[0061] like Figure 7 As shown, Figure 7This is the first application circuit scheme for an IGBT module integrating series diodes. An operational amplifier is used for voltage detection, including the basic drive circuit: the microcontroller drives the gate (G) of the IGBT through resistor R2, capacitor C1 is a filter capacitor, and resistor R1 is a pull-down resistor. The series diode circuit uses n series diodes integrated within the IGBT module. The anode is connected to the common node between R1 and the emitter (E) of the IGBT, while the cathode (or base) is either floating or connected to the op-amp input via feedback resistor Rf. The operational amplifier detection circuit includes: feedback resistor Rf: connected between the op-amp's v- input and the upper end of R1, used for current-to-voltage conversion or voltage sampling. The op-amp's positive input v+: connected to ground or a reference voltage. The op-amp's negative input v-: connected to the common node between R1 and the series diodes via Rf, forming an inverting amplification or transimpedance amplification configuration. The op-amp output: connected to the microcontroller's AD sampling pin, used to detect the voltage drop or current signal of the series diodes.

[0062] In this embodiment, when the IGBT is working, the current or voltage change through the series diode is converted and amplified by the operational amplifier circuit and then output to the microcontroller. The microcontroller can use this signal to determine the operating status of the IGBT, the overcurrent condition, or to implement other protection functions. The ratio of Rf to R1 determines the amplification factor.

[0063] like Figure 8 As shown, Figure 8 This is a second application circuit scheme for an IGBT module with integrated series diodes, and... Figure 7 The operational amplifier (op-amp) differs in its input configuration, including the basic circuitry: microcontroller, resistor R2, capacitor C1, IGBT, and resistor RL. The operational amplifier configuration differs as follows: The positive input terminal (v+) is connected to the common node (T-signal point) between the emitter (E) of the IGBT and resistor R1, directly detecting the voltage at this point. The negative input terminal (v-) is connected via resistor Rf, with the other end possibly grounded or connected to a reference voltage, forming a non-inverting amplifier configuration. The feedback resistor Rf is located between the op-amp output and the v- input terminal, and together with resistor R1, determines the gain of the non-inverting amplifier.

[0064] This embodiment uses a non-inverting amplifier configuration to amplify the voltage at the T-pole and output it to the microcontroller's AD sampling pin. Compared to Figure 7 Inverse configuration, Figure 8 The in-phase configuration features high input impedance and does not generate a load effect on the T-node, making it suitable for detecting high-impedance signal sources. The two circuit schemes can be selected based on the specific requirements of the application regarding signal polarity, gain, and input impedance.

[0065] In this embodiment, the specific implementation of each unit in the above device embodiment is described in the above method embodiment, and will not be repeated here.

[0066] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, apparatus, article, or method that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, apparatus, article, or method. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, apparatus, article, or method that includes that element.

[0067] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for detecting the junction temperature of an IGBT module, characterized in that, include: S1: The microcontroller outputs a PWM drive signal to the gate of the IGBT wafer to turn on the IGBT wafer. S2: Perform thermal conductivity sensing on the NTC wafer that is encapsulated in the same package as the IGBT wafer, and generate a T-terminal voltage signal by connecting the NTC wafer to the T-terminal pin and forming a voltage divider circuit with a pull-down resistor. S3: Perform AD conversion on the T-terminal voltage signal to obtain the digital value of the T-terminal voltage. Calculate the NTC resistance value of the NTC wafer based on the digital value of the T-terminal voltage and look up the preset temperature data table to obtain the current junction temperature value of the IGBT wafer. S4: Compare the current junction temperature value with a preset protection threshold. When the current junction temperature value is greater than or equal to the preset protection threshold, turn off the PWM drive signal. When the current junction temperature value is less than the preset protection threshold, continue to output the PWM drive signal and repeat steps S2 to S4.

2. The junction temperature detection method for an IGBT module according to claim 1, characterized in that, Step S1 includes: S11: The microcontroller configures the PWM drive signal and transmits it to the gate of the IGBT wafer through the drive resistor; S12: When the PWM drive signal is high, the IGBT wafer is turned on to form a load current loop and generate power loss heat.

3. The junction temperature detection method for an IGBT module according to claim 1, characterized in that, Step S2 includes: S21: The power loss heat generated by the IGBT wafer is sensed by the NTC wafer encapsulated in the same package as the IGBT wafer; S22: Connect one end of the NTC wafer to the T-pin via a bonding wire, and connect the other end of the NTC wafer to the emitter, forming a voltage divider circuit with the pull-down resistor; S23: Based on the voltage divider circuit, a T-pin voltage signal reflecting the change in NTC resistance value is generated at the T-pin.

4. The junction temperature detection method for an IGBT module according to claim 3, characterized in that, Step S23 includes: S231: Apply a regulated power supply to the voltage divider circuit formed by the NTC wafer and the pull-down resistor; S232: Based on the change in the NTC resistance value of the NTC wafer in the voltage divider circuit, a corresponding voltage divider voltage is obtained at the T-pin; S233: The voltage divider voltage of the T-pin is filtered by the filter capacitor to obtain the T-pin voltage signal.

5. The junction temperature detection method for an IGBT module according to claim 1, characterized in that, Step S3 includes: S31: The microcontroller's AD converter performs analog-to-digital conversion on the T-pole voltage signal to obtain the digital value of the T-pole voltage; S32: Calculate the NTC resistance value of the NTC wafer based on the digital value of the T-pole voltage, the voltage value of the regulated power supply, and the resistance value of the pull-down resistor; S33: Based on the NTC resistance value, look up the preset temperature data table to obtain the current junction temperature value of the IGBT wafer.

6. The junction temperature detection method for an IGBT module according to claim 5, characterized in that, Step S31 includes: S311: The microcontroller triggers the AD converter to select the analog input channel connected to the T terminal and starts the sample-and-hold circuit. The sampling capacitor of the sample-and-hold circuit charges and samples the voltage signal of the T terminal to obtain the holding voltage value. S312: The AD converter quantizes the holding voltage value and stores it in the data register to obtain the digital value of the T-pole voltage.

7. The junction temperature detection method for an IGBT module according to claim 6, characterized in that, Step S32 includes: S321: Multiply the digital value of the T-pin voltage by the quantization step value to obtain the actual voltage value of the T-pin. S322: Subtract the actual voltage value from the voltage value of the regulated power supply to obtain the voltage divider value on the NTC wafer; S323: Multiply the resistance value of the pull-down resistor by the ratio of the voltage divider value on the NTC wafer to the actual voltage value to obtain the NTC resistance value of the NTC wafer.

8. The junction temperature detection method for an IGBT module according to claim 1, characterized in that, Step S4 includes: S41: The microcontroller reads the preset protection threshold and compares it with the current junction temperature value; S42: When the current junction temperature value is greater than or equal to the preset protection threshold, the microcontroller will force the PWM output pin to be pulled low to 0V to turn off the PWM drive signal; S43: When the current junction temperature is less than the preset protection threshold, the microcontroller maintains the PWM drive signal output and returns to execute steps S2 to S4.

9. The junction temperature detection method for an IGBT module according to claim 8, characterized in that, Step S42 includes: S421: The microcontroller forces the PWM output pin level connected to the drive resistor to 0V, stopping the PWM drive signal output; S422: The driving resistor stops transmitting driving current to the gate of the IGBT wafer, the gate voltage is discharged to 0V through the pull-down path, the IGBT wafer changes from the on state to the off state, and the load current loop is cut off.

10. A junction temperature detection device for an IGBT module, characterized in that, The steps for implementing the junction temperature detection method of the IGBT module according to any one of claims 1 to 9 include: an IGBT module comprising an NTC wafer and an IGBT wafer, a sampling circuit, a filtering circuit, a microcontroller, and a power supply circuit; the NTC signal terminal of the IGBT module is electrically connected to the sampling circuit, the sampling circuit is electrically connected to the filtering circuit, and the filtering circuit is connected to the microcontroller; the power supply circuit is used to provide operating power.

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