Device and method for overload and overcurrent multiplex protection of an igbt module

Abstract

The application relates to the field of motor safety protection, in particular to a device and method for overload and overcurrent multiplex protection of an IGBT module. Mainly comprising an overload identification module, an overload protection threshold setting module and an overload and overcurrent signal multiplexing module: the first input port of the overload identification module is connected with an NTC resistance temperature output pin of the IGBT module, and is used for receiving a voltage value signal corresponding to the temperature of the IGBT module; the overload protection threshold setting module is used for receiving a PWM signal corresponding to a temperature threshold value sent by an external microprocessor, and converting the PWM signal into a voltage signal of a hot ground end; the input port of the overload and overcurrent signal multiplexing module is connected with an overcurrent protection pin of the IGBT module, the voltage value signal corresponding to the temperature and the overcurrent protection signal are combined, abnormal information of the overload and overcurrent is converted into a signal of a cold ground end, and the signal is fed back to the external microprocessor. The application can output abnormal signals when overcurrent and overload occur, and conversion between the cold ground end and the hot ground end is carried out.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of motor safety protection, in particular to an overload and overcurrent multiplex protection device and method for IGBT module. BACKGROUND

[0002] Insulated Gate Bipolar Transistor (IGBT) is a kind of power tube device controlled by weak current. In the operation of the motor, when the motor drive system is overloaded, the power tube device will cause overcurrent in a short time, resulting in loss of control of the motor, and even causing fire and other hazards to human life and equipment, so it is necessary to protect the IGBT in time.

[0003] At present, the overload state of IGBT module in motor drive system is generally judged by temperature, so the overload state can be equivalent to the overtemperature state, which can be monitored by the Negative Temperature Coefficient (NTC) temperature sensor of IGBT module. However, in the high-voltage IGBT environment of industrial fast door motor servo drive, the IGBT module is isolated from the cold ground end of the microcontroller unit (MCU) used for controlling the start of the motor, in order to protect the digital circuits such as MCU and sensors in the cold ground end. The MCU can send digital control signals to the IGBT module in one direction through an optical coupler, but the resistance level signal output by the NTC temperature sensor in the IGBT module is difficult to input to the MCU in the cold ground end through the optical coupler. In addition, there is a time lag relationship between the temperature of IGBT and the overload of IGBT module, which is difficult to obtain the overload device of IGBT module in time from the temperature information

[0004] As for the overcurrent protection of IGBT module, the overcurrent output pin of hot ground IGBT module is used to output the overcurrent protection action result based on current sampling data, and it is difficult to know the cause of overcurrent from the overcurrent protection action signal, that is, it is impossible to determine whether the cause of overcurrent protection is simply overcurrent or overload, which brings challenges to the selection of further protection action or recovery action.

[0005] In actual engineering, the most direct method to solve the above problems is to set an independent MCU and its peripheral circuit in the hot ground end for overload and overcurrent protection of IGBT module, but the independent circuit working in the hot ground end will increase the total cost of motor servo drive system, and the high-voltage fluctuation environment in the hot ground end is also easy to cause damage or abnormal work of the independent MCU and its peripheral circuit.

[0006] Therefore, how to overcome the shortcomings of existing technologies and solve the problem of inconvenience in obtaining overload and overcurrent states during motor servo control is a problem to be solved in this technical field. Summary of the Invention

[0007] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention solves the problem of inconvenience in obtaining overload and overcurrent status during motor servo control.

[0008] The embodiments of the present invention adopt the following technical solutions:

[0009] In a first aspect, the present invention provides an overload and overcurrent multiplexing protection device for an IGBT module, specifically comprising an overload identification module, an overload protection threshold setting module, and an overload and overcurrent signal multiplexing module. Specifically: the first input port of the overload identification module is connected to the NTC resistor temperature output pin of the IGBT module, for receiving the voltage value signal corresponding to the temperature of the IGBT module; the output port of the overload protection threshold setting module is connected to the second input port of the overload identification module, and the input port of the overload protection threshold setting module is connected to the output port of an external microprocessor at the cold ground terminal, for receiving the PWM signal corresponding to the temperature threshold value sent by the external microprocessor and converting it into a voltage signal at the hot ground terminal; the input port of the overload and overcurrent signal multiplexing module is connected to the overcurrent protection pin of the IGBT module, and the input port of the overload and overcurrent signal multiplexing module is connected to the output port of the overload identification module, combining the voltage value signal corresponding to the temperature and the overcurrent protection signal; the output port of the overload and overcurrent signal multiplexing module is connected to the input pin of the external microprocessor, converting the overload and overcurrent abnormal information into a signal at the cold ground terminal and feeding it back to the external microprocessor.

[0010] Preferably, the overload and overcurrent signal multiplexing module includes a first single Schmitt trigger buffer and a first optocoupler. Specifically, the output pin of the first single Schmitt trigger buffer is connected to the second input terminal of the first optocoupler through a voltage divider resistor connected to a 5V power supply, which is used to increase the driving capability of the first optocoupler; the first input terminal of the first optocoupler is connected to a 5V power supply, the third output pin of the first optocoupler is grounded, and the fourth output pin outputs an abnormal signal to the microprocessor through a 3.3V power supply pull-up resistor connected to the cold ground terminal, which is used to transmit the abnormal signal from the hot ground terminal to the external microprocessor at the cold ground terminal.

[0011] Preferably, the overcurrent protection pin of the IGBT module and the output port of the overload identification module are both connected to the input pin of the first single Schmitt trigger buffer, so that the output of the overcurrent protection pin of the IGBT module and the signal output of the overload identification module form a wired-AND relationship.

[0012] Preferably, the overload identification module includes a voltage comparator. Specifically, the first input port of the voltage comparator is connected to the NTC resistor temperature output pin of the IGBT module, the second input port of the voltage comparator is used for overload protection threshold setting, the second input port of the voltage comparator is connected to the output port of the overload protection threshold setting module, and the output port of the voltage comparator is connected to the input module of the overload and overcurrent signal multiplexing module.

[0013] Preferably, the overload protection threshold setting module includes a second optocoupler, a second single Schmitt trigger buffer, and an operational amplifier. Specifically, the second optocoupler, the second single Schmitt trigger buffer, and the operational amplifier are connected in sequence. The second optocoupler is used for the transmission of the overload protection threshold pulse width modulation signal from the cold ground to the hot ground. The second single Schmitt trigger buffer is used to convert the overload protection threshold pulse width modulation signal into a level signal. The operational amplifier is used to form a second-order low-pass active filter to denoise the level signal.

[0014] On the other hand, the present invention provides a method for overload and overcurrent multiplexing protection of an IGBT module, specifically: using the overload and overcurrent multiplexing protection device for an IGBT module provided in the first aspect, specifically: an overload protection threshold setting module acquires the PWM signal corresponding to the temperature threshold value input by the external microprocessor at the cold ground terminal, converts the PWM signal corresponding to the temperature threshold value into a threshold voltage at the hot ground terminal, and inputs the threshold voltage to the overload identification module; the overload identification module compares the threshold voltage with the voltage value corresponding to the temperature output by the IGBT module, performs a wired AND operation between the output of the voltage comparator and the output of the overcurrent protection pin of the IGBT module, and outputs the wired AND result as a voltage value to the overload and overcurrent signal multiplexing module; the overload and overcurrent signal multiplexing module converts the voltage value of the wired AND result at the hot ground terminal into an abnormal signal at the cold ground terminal and outputs it to the external microprocessor, and the external microprocessor performs corresponding control on the IGBT module according to the abnormal signal.

[0015] Preferably, the overload identification module compares the threshold voltage with the voltage value corresponding to the temperature output by the IGBT module. Specifically, this includes: lowering the temperature threshold value according to a specified cycle until the temperature threshold value is lower than the voltage corresponding to the temperature output by the IGBT module. At this time, the temperature value corresponding to the temperature threshold value is the current temperature of the IGBT module.

[0016] Preferably, the external microprocessor controls the IGBT module accordingly based on the abnormal signal, specifically including: the external microprocessor receives the abnormal signal output by the overload and overcurrent signal multiplexing module, and determines whether the abnormal signal is an overcurrent signal or an overload signal; if it is an overcurrent signal, the IGBT module is frequently monitored for overcurrent; if it is an overload signal, the IGBT module is allowed to return to normal operation after its temperature drops to the normal operating temperature.

[0017] Preferably, identifying an abnormal signal as an overcurrent signal or an overload signal specifically includes: raising the temperature threshold to a specified high temperature value and detecting the abnormal signal again; if the abnormal signal disappears, the current signal is an overload signal; if the abnormal signal does not disappear, the current signal is an overcurrent signal.

[0018] Preferably, the frequent overcurrent monitoring of the IGBT module specifically includes: if an overload anomaly occurs after multiple consecutive overcurrent recovery, setting the overcurrent recovery time of the next overcurrent recovery to a specified multiple of the total continuous overcurrent recovery time, and restoring the normal operation of the IGBT module after the temperature of the IGBT module is lower than a specified low temperature value.

[0019] Compared with existing technologies, the beneficial effects of this invention are as follows: It multiplexes the overcurrent and overload signals in the IGBT, outputting abnormal signals in both overcurrent and overload conditions, and performs cold ground and hot ground conversion. This allows the signal conversion and transmission circuitry in the device to transmit both signals across the hot and cold ground terminals, saving on the total cost of the hot and cold ground conversion and transmission circuitry components, and reducing the number of I / O pins used by the cold ground microprocessor. Furthermore, in the preferred embodiment, by distinguishing between overcurrent and overload signals in the abnormal signals, overcurrent and overload signals are effectively identified. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0021] Figure 1 A schematic diagram of an overload and overcurrent multiplexing protection device for an IGBT module provided in an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of an overload and overcurrent signal multiplexing module provided in an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of an overload and overcurrent signal multiplexing module provided in an embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of the overload identification module provided in an embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of the overload protection threshold setting module provided in an embodiment of the present invention;

[0026] Figure 6This is a flowchart illustrating a method for overload and overcurrent multiplexing protection of an IGBT module, as provided in an embodiment of the present invention. Detailed Implementation

[0027] 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.

[0028] This invention is an architecture of a specific functional system. Therefore, the specific embodiments mainly describe the functional logic relationship of each structural module, and do not limit the specific software and hardware implementation methods.

[0029] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] Example 1:

[0031] In this embodiment, an overload protection threshold setting module and an overload identification module that span the hot and cold ground ends are designed. The overload state is corresponding to the overtemperature state. The overload is judged by the temperature. The current NTC temperature can be detected at the cold ground end, so that the microprocessor of the motor servo system can stably capture the IGBT module overload event at the cold ground end.

[0032] Taking Mitsubishi Electric's PSS50S71F6 IGBT module as an example:

[0033] Overcurrent mechanism: When the current through R131-R132-R147 of the IGBT module is too large, FAULT will trigger pin U28-PIN26 of the IGBT module, turning off all 6 internal IGBTs, and outputting a low-level pulse VFO of about 1ms through pin U28-PIN24. VFO drives optocoupler U38 through U17, outputting CUR_FLT to inform the MCU that an abnormality has occurred.

[0034] Overload (overtemperature) mechanism: When the load exceeds the rated value or the IGBT is overloaded due to frequent overcurrent, the junction temperature inside the IGBT will be too high. The NTC resistor to ground of the IGBT module U28-PIN28 will change. The hysteresis comparator composed of high-speed comparator U40 will detect whether an overload has occurred according to the temperature threshold set by VREF_SET. When it is activated, VFO is at a low level.

[0035] The device provided in this embodiment is as follows: Figure 1 As shown, it includes an overload identification module, an overload protection threshold setting module, and an overload and overcurrent signal multiplexing module.

[0036] The first input port of the overload identification module is connected to the NTC resistor temperature output pin of the IGBT module. It receives the voltage value signal corresponding to the temperature of the IGBT module and the overcurrent protection signal, and combines these two signals. The voltage value signal corresponding to the temperature of the IGBT module is referred to as the overload protection threshold signal. The overload identification module uses the voltage value of the overload protection threshold signal as a reference to determine whether the IGBT module is over-temperature (overloaded). Taking the Mitsubishi Electric PSS50S71F6 IGBT module as an example, the overload protection threshold signal is output from the TH pin (pin 28) of the IGBT module, representing the temperature of the motor servo controlled by the IGBT module as a voltage value. The overcurrent protection signal is provided by the overcurrent protection pin (pin 24) of the IGBT module. When this pin outputs a low level, it indicates that the overcurrent protection is activated, the IGBT module has protected the motor servo, and the motor does not operate.

[0037] The output port (VREF_SET) of the overload protection threshold setting module is connected to the second input port of the overload identification module. The input port of the overload protection threshold setting module is connected to the output port of the external microprocessor at the cold ground terminal. It is used to receive the PWM signal corresponding to the temperature threshold value sent by the external microprocessor and convert it into a voltage signal at the hot ground terminal. In the device of this embodiment, the temperature threshold value is set by the external MCU, and the current temperature value is obtained by probing the decrease of the temperature threshold value. However, the external MCU is located at the cold ground terminal. Therefore, the overload protection threshold setting module also needs to transmit the overload protection threshold pulse width modulation signal sent by the microprocessor at the hot ground terminal to the hot ground terminal and convert it into a corresponding level signal.

[0038] The input port of the overload and overcurrent signal multiplexing module is connected to the overcurrent protection pin of the IGBT module. The input port of the overload and overcurrent signal multiplexing module is also connected to the output port (VFO) of the overload identification module. The output port of the overload and overcurrent signal multiplexing module is connected to the input pin of an external microprocessor, providing feedback of overload and overcurrent abnormal information to the external microprocessor. The overload and overcurrent signal multiplexing module performs a wired AND operation on the overload signal and the overcurrent signal, then amplifies the multiplexed signal before transmitting it to the microprocessor at the cold ground terminal.

[0039] like Figure 2 As shown, the overload and overcurrent signal multiplexing module includes a first single Schmitt trigger buffer (U17) and a first optocoupler.

[0040] The output pin (Y pin) of the first single Schmitt trigger buffer (U17) is connected to the second input of the first optocoupler through a voltage divider resistor R188 (10kΩ) with a 5V power supply, in order to increase the driving capability of the first optocoupler.

[0041] The first input terminal of the first optocoupler is connected to a 5V power supply, the third output pin of the first optocoupler is grounded, and the fourth output pin outputs an overload and overcurrent failure signal to the microprocessor through a 3.3V power supply pull-up resistor R195 (3KΩ) connected to the cold ground terminal. This signal is used to transmit the overload and overcurrent signal from the hot ground terminal to the external microprocessor at the cold ground terminal, thereby completing the conversion between the hot ground terminal signal and the cold ground terminal signal.

[0042] In specific implementation, such as Figure 3 As shown, taking the first optocoupler of model HCPL-817 as an example, the overcurrent protection pin VFO of the IGBT module and the output port of the overtemperature identification module are both connected to the input pin (pin A) of the first single Schmitt trigger buffer (U17), so that the output of the overcurrent protection pin VFO of the IGBT module and the signal output of the overload identification module form a wired AND relationship, thereby sharing the overload and overcurrent signal multiplexing module.

[0043] Furthermore, such as Figure 4 As shown, the overload identification module can be implemented using a voltage comparator. The first input port of the voltage comparator is connected to the NTC resistor temperature output pin of the IGBT module. The second input port of the voltage comparator is used for overload protection threshold setting and is connected to the output port of the overload protection threshold setting module. The output port of the voltage comparator is connected to the input module of the overload and overcurrent signal multiplexing module. Since the overcurrent protection pin VFO of the IGBT module shares a connection point with the output port of the overload identification module, and the overcurrent protection pin VFO can also be used as the input pin of the IGBT module for over-temperature protection, both overcurrent and overload can be addressed by adjusting the temperature threshold value of the second input port of the overload identification module through the overload protection threshold setting module to lower the overcurrent protection pin VFO and protect the IGBT module. In specific implementations, a voltage comparator of model LMV331 can be used.

[0044] like Figure 5 As shown, the overload protection threshold setting module includes a second optocoupler, a second single Schmitt trigger buffer, and an operational amplifier. The second optocoupler, the second single Schmitt trigger buffer, and the operational amplifier are connected in sequence.

[0045] The second optocoupler is used for the transmission of the overload protection threshold pulse width modulation signal from the cold ground to the hot ground. Specifically, the second optocoupler can be a single-channel high-speed optocoupler, such as the 6N137.

[0046] The second single Schmitt trigger buffer is used to convert the overload protection threshold pulse width modulation signal into a level signal. The functions of the second single Schmitt trigger buffer are: a. to increase the output drive capability; b. to ensure output accuracy by performing level conversion, converting the 5V square wave into a square wave powered by a 3V reference source with an accuracy of 0.5% and 100ppm to ensure accurate output PWM amplitude. Both the first and second single Schmitt trigger buffers can use the SN74LVC1G17 model.

[0047] The operational amplifier is used to construct a second-order low-pass active filter to denoise the level signal. The second-order low-pass active filter provides an attenuation performance of 40dB / dec. The cutoff frequency of the filter is set to 200Hz, which can ensure that the PWM fundamental frequency attenuation amplitude is 80dB, accurately demodulate the command signal, and then accurately set the temperature protection threshold VREF_SET.

[0048] The overload and overcurrent multiplexing protection device for the IGBT module provided in this embodiment is designed with an overload and overload signal multiplexing module that is shared by both overcurrent and overload signals. This allows a single signal conversion and transmission circuit to realize the transmission of two signals across the hot ground and cold ground terminals, which saves the total cost of the conversion and transmission circuit devices for the hot ground and cold ground terminals and also reduces the number of I / O pins used by the microprocessor on the cold ground terminal.

[0049] Example 2:

[0050] Based on the overload and overcurrent multiplexing protection device for the IGBT module provided in Embodiment 1, this embodiment also provides a method for overload and overcurrent multiplexing protection of the IGBT module, which realizes direct temperature detection of the IGBT module by the MCU through MCU temperature drop detection.

[0051] like Figure 6 As shown, the overload and overcurrent multiplexing protection method for the IGBT module provided in this embodiment includes the following steps.

[0052] Step 101: The overload protection threshold setting module obtains the PWM signal corresponding to the temperature threshold value input by the external microprocessor at the cold ground end, converts the PWM signal corresponding to the temperature threshold value into the threshold voltage at the hot ground end, and inputs the threshold voltage to the overload identification module.

[0053] Step 102: The overload identification module compares the threshold voltage with the voltage value corresponding to the temperature output by the IGBT module, performs a wired AND operation between the output of the voltage comparator and the output of the overcurrent protection pin of the IGBT module, and outputs the wired AND result as a voltage value to the overload and overcurrent signal multiplexing module.

[0054] Step 103: The overload and overcurrent signal multiplexing module converts the voltage value of the hot ground terminal and the result into an abnormal signal (CUR_FLT) of the cold ground terminal and outputs it to the external microprocessor. The external microprocessor performs corresponding control on the IGBT module according to the abnormal signal (CUR_FLT).

[0055] As can be seen from the above steps, the method provided in this embodiment can use the device provided in Embodiment 1 to identify overload and overcurrent signals and provide corresponding protection for the motor servo. Furthermore, in specific implementations, since the above steps are implemented through circuits, the steps can be executed in parallel.

[0056] The MCU outputs a command signal VRE_PWM, which is a square wave waveform; its switching frequency is set to 20kHz, and the duty cycle can be adjusted from 0% to 100% according to the temperature setting command.

[0057] VRE_PWM drives the high-speed optocoupler U47. The optocoupler is turned on when the level is low and turned off when the level is high. U47 is a high-speed optocoupler with a 10Mbit rate. The optocoupler is powered by a digital power supply +5V_P. U47-PIN6 is a +5V square wave with the same frequency as the command signal.

[0058] A +5V square wave signal drives digital U49 via R219. U49 is a digital buffer that converts the pulse width modulation signal into a level signal.

[0059] The U49-PIN4 high-frequency PWM signal is used to output a precise level signal through a second-order low-pass active filter composed of operational amplifiers.

[0060] In the method provided in this embodiment, over-temperature detection is performed by probing the temperature drop of the MCU. The temperature threshold is lowered periodically until it falls below the voltage corresponding to the temperature output by the IGBT module. The temperature corresponding to this threshold is the current temperature of the IGBT module. For example, if the threshold is set to 120℃, the VREF_SET threshold is lowered every minute until the CUR_FLT signal goes low. If an overload is detected causing CUR_FLT to go low, the process continues until CUR_FLT goes high. The set temperature threshold at this point is the current temperature of the IGBT module.

[0061] The device provided in Example 1 outputs an abnormal signal for both overload and overcurrent signals. Therefore, the external microprocessor receives the abnormal signal (CUR_FLT) output by the overload and overcurrent signal multiplexing module and determines whether the abnormal signal (CUR_FLT) is an overcurrent signal or an overload signal.

[0062] Different anomaly handling is required after identifying different signals. If it is an overcurrent signal, the IGBT module is frequently monitored for overcurrent; if it is an overload signal, the IGBT module is restored to normal operation after its temperature drops to the normal operating temperature.

[0063] The specific judgment method is as follows: raise the temperature threshold to the specified high temperature value and check the abnormal signal again; if the abnormal signal disappears, the current signal is an overload signal; if the abnormal signal does not disappear, the current signal is an overcurrent signal. For example: under normal conditions, the protection is set to 120℃, and the hysteresis temperature to exit the protection is 100℃; when an overload or overcurrent abnormal signal is detected, the MCU immediately sets the temperature threshold to 150℃ and checks the CUR_FLT signal again; if it is an overload, when the MCU raises the temperature threshold, the threshold temperature will be higher than the current temperature, and the abnormal temperature will disappear; if it is an overcurrent, raising the temperature will not make the abnormal signal disappear.

[0064] Considering the positive correlation between overload and overload, but with a delay in the connection, this embodiment also designs a frequent overcurrent monitoring method. This method allows for the capture of actual overload events due to frequent overcurrent before an overload occurs, and specifically delays the recovery of the IGBT module. This further improves the overcurrent and overload protection capability of the motor servo system and avoids overheating caused by prolonged overcurrent, which could lead to overload. Specifically, if an overload anomaly occurs after multiple consecutive overcurrent recovery cycles, the overcurrent recovery time for the next recovery cycle is set to a specified multiple of the total continuous overcurrent recovery time. The IGBT module is then restored to normal operation once its temperature drops below a specified low temperature. For example, if each overcurrent recovery cycle is 10 seconds, and a true overload occurs after five consecutive overcurrent cycles, the next recovery time is set to at least 10 minutes, and the temperature is monitored to be below 50°C using an IGBT module temperature detection method.

[0065] As can be seen from the specific implementation process of the above method, the method provided in this embodiment can realize the overload and overcurrent multiplexing protection of the IGBT module based on the device in Embodiment 1.

[0066] 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 device for overload and overcurrent multiplexing protection of an IGBT module, characterized in that, It includes an overload identification module, an overload protection threshold setting module, and an overload and overcurrent signal multiplexing module, specifically: The first input port of the overload identification module is connected to the NTC resistor temperature output pin of the IGBT module, and is used to receive the voltage value signal corresponding to the temperature of the IGBT module. The output port of the overload protection threshold setting module is connected to the second input port of the overload identification module, and the input port of the overload protection threshold setting module is connected to the output port of the external microprocessor at the cold ground end. It is used to receive the PWM signal corresponding to the temperature threshold value sent by the external microprocessor and convert it into a voltage signal at the hot ground end. The input port of the overload and overcurrent signal multiplexing module is connected to the overcurrent protection pin of the IGBT module. The input port of the overload and overcurrent signal multiplexing module is connected to the output port of the overload identification module. It combines the voltage value signal corresponding to the temperature and the overcurrent protection signal. The output port of the overload and overcurrent signal multiplexing module is connected to the input pin of the external microprocessor. It converts the abnormal information of overload and overcurrent into a cold ground terminal signal and feeds it back to the external microprocessor. The overload and overcurrent signal multiplexing module includes a first single Schmitt trigger buffer. The overcurrent protection pin of the IGBT module and the output port of the overload identification module are both connected to the input pin of the first single Schmitt trigger buffer, so that the output of the overcurrent protection pin of the IGBT module and the signal output of the overload identification module form a wired AND relationship. The external microprocessor is used to receive the abnormal signal output by the overload and overcurrent signal multiplexing module. When the external microprocessor receives the abnormal signal, it raises the temperature threshold to the specified high temperature value and detects the abnormal signal again. If the abnormal signal disappears, the current signal is an overload signal; if the abnormal signal does not disappear, the current signal is an overcurrent signal.

2. The overload and overcurrent multiplexing protection device for an IGBT module according to claim 1, characterized in that, The overload and overcurrent signal multiplexing module also includes a first optocoupler, specifically: The output pin of the first single Schmitt trigger buffer is connected to the second input terminal of the first optocoupler through a voltage divider resistor with a 5V power supply, in order to increase the driving capability of the first optocoupler; The first input terminal of the first optocoupler is connected to a 5V power supply, the third output pin of the first optocoupler is grounded, and the fourth output pin outputs an abnormal signal to the microprocessor through a 3.3V power supply pull-up resistor connected to the cold ground terminal, which is used to transmit the abnormal signal from the hot ground terminal to the external microprocessor at the cold ground terminal.

3. The overload and overcurrent multiplexing protection device for an IGBT module according to claim 1, characterized in that, The overload identification module includes a voltage comparator, specifically: The first input port of the voltage comparator is connected to the NTC resistor temperature output pin of the IGBT module. The second input port of the voltage comparator is used for overload protection threshold setting. The second input port of the voltage comparator is connected to the output port of the overload protection threshold setting module. The output port of the voltage comparator is connected to the input module of the overload and overcurrent signal multiplexing module.

4. The overload and overcurrent multiplexing protection device for an IGBT module according to claim 1, characterized in that, The overload protection threshold setting module includes a second optocoupler, a second single Schmitt trigger buffer, and an operational amplifier, specifically: The second optocoupler, the second single Schmitt trigger buffer, and the operational amplifier are connected in sequence. The second optocoupler is used to transmit the overload protection threshold pulse width modulation signal from the cold ground to the hot ground. The second single Schmitt trigger buffer is used to convert the overload protection threshold pulse width modulation signal into a level signal. The operational amplifier is used to form a second-order low-pass active filter to denoise the level signal.

5. A method for overload and overcurrent multiplexing protection of an IGBT module, characterized in that, The overload and overcurrent multiplexing protection device for the IGBT module according to any one of claims 1-4 specifically includes: The overload protection threshold setting module obtains the PWM signal corresponding to the temperature threshold value input by the external microprocessor at the cold ground end, converts the PWM signal corresponding to the temperature threshold value into the threshold voltage at the hot ground end, and inputs the threshold voltage to the overload identification module. The overload identification module compares the threshold voltage with the voltage value corresponding to the temperature output by the IGBT module, performs a wired AND operation between the output of the voltage comparator and the output of the overcurrent protection pin of the IGBT module, and outputs the wired AND result as a voltage value to the overload and overcurrent signal multiplexing module. The overload and overcurrent signal multiplexing module converts the voltage value of the hot ground terminal and the result into an abnormal signal of the cold ground terminal and outputs it to the external microprocessor. The external microprocessor then controls the IGBT module accordingly based on the abnormal signal.

6. The overload and overcurrent multiplexing protection method for an IGBT module according to claim 5, characterized in that, The overload identification module compares the threshold voltage with the voltage value corresponding to the temperature output by the IGBT module, specifically including: The temperature threshold is lowered periodically until it falls below the voltage corresponding to the temperature output by the IGBT module. At this point, the temperature threshold corresponds to the current temperature of the IGBT module.

7. The overload and overcurrent multiplexing protection method for an IGBT module according to claim 5, characterized in that, The external microprocessor controls the IGBT module according to the abnormal signal, specifically including: if it is an overcurrent signal, the external microprocessor performs frequent overcurrent monitoring on the IGBT module; If it is an overload signal, the external microprocessor will wait for the IGBT module temperature to drop to the normal operating temperature before resuming normal operation of the IGBT module.

8. The overload and overcurrent multiplexing protection method for an IGBT module according to claim 5, characterized in that, The frequent overcurrent monitoring of the IGBT module specifically includes: If an overload anomaly occurs after multiple consecutive overcurrent recovery cycles, the overcurrent recovery time for the next overcurrent recovery cycle will be set to a specified multiple of the total consecutive overcurrent recovery time, and the IGBT module will resume normal operation once its temperature drops below a specified low temperature value.

Images