BUCK switching power supply fault diagnosis system and method based on intelligent monitoring

Abstract

The invention relates to the technical field of power electronics, and discloses a BUCK switching power supply fault diagnosis system and method based on intelligent monitoring, and the system comprises a BUCK switching power supply main circuit, an MCU control unit, an input voltage detection circuit, a switching tube temperature detection circuit, an output current detection circuit, an output voltage detection circuit, and a switching tube state detection circuit. The method comprises the following steps: detecting input voltage, temperature, output current and output voltage signals; differentiating the driving signal, and generating a switching tube fault diagnosis signal by the comparator; setting an input voltage threshold value, a temperature threshold value, an output current threshold value and an output voltage threshold value; judging whether the signal exceeds a threshold value or not; and in case of abnormality, protection is triggered, and faults are identified and reported to the upper computer for display. Through a fault diagnosis algorithm of the MCU control unit, a protection mechanism is triggered according to a comparison result of a detection signal and a threshold range, so that fault diffusion is avoided, and the safety of a power supply and a downstream circuit connected with the power supply is ensured.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, specifically to a fault diagnosis system and method for BUCK switching power supplies based on intelligent monitoring. Background Technology

[0002] With the rapid development of electronic devices, products are becoming increasingly complex and intelligent, and the variety of embedded electronic products is also increasing. In complex electronic product systems, intelligent status management with self-diagnosis and automatic checks has become an essential requirement. As the core component of electronic products, power modules not only need to provide the various voltage conversions and power outputs required by the product, but their intelligent control is also a key requirement for meeting the system's demands on each sub-circuit.

[0003] Currently, digitally controlled power modules have become core mainstream products, widely used in various electronic systems. Using microcontrollers (MCUs) as the core control unit of digital power supplies enables complex control strategies and precise status detection, greatly improving the product's intelligence and functional integration. However, with the increasing complexity of digital power supplies, the types and varieties of potential faults also increase significantly.

[0004] However, existing BUCK switching power supply fault diagnosis systems are often limited to simple over-limit judgments of output voltage or current, lacking a comprehensive perception of the power supply's multi-dimensional operating status. In terms of real-time monitoring and emergency handling, existing systems have insufficient response capabilities and are also deficient in fault information presentation and user interaction. After a fault occurs, manual intervention is often required for complex troubleshooting, which is time-consuming and labor-intensive. Therefore, this invention provides a BUCK switching power supply fault diagnosis system and method based on intelligent monitoring to address the shortcomings of existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this application is to provide a fault diagnosis system and method for BUCK switching power supplies based on intelligent monitoring, which solves the problems of existing BUCK switching power supply fault diagnosis systems having limited functionality and lacking real-time monitoring and emergency response capabilities.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of this invention provides a fault diagnosis system for a BUCK switching power supply based on intelligent monitoring, comprising: BUCK switching power supply main circuit, including switching transistors; The MCU control unit is electrically connected to the main circuit of the BUCK switching power supply. This MCU control unit is used to generate pulse width modulation (PWM) signals to control the operating state of the BUCK switching power supply main circuit, perform data processing tasks, determine fault types, and perform communication operations. An input voltage detection circuit is electrically connected to the input terminal of the BUCK switching power supply main circuit. This input voltage detection circuit is used to detect the input voltage of the BUCK switching power supply main circuit in real time and output an input voltage signal. To the MCU control unit; The switching transistor temperature detection circuit includes an NTC thermistor R0 and a voltage divider resistor R1. The NTC thermistor R0 is directly mounted on the surface of the heatsink of the switching transistor. The switching transistor temperature detection circuit is used to detect the temperature of the switching transistor in real time and output a temperature signal. To the MCU control unit; The output current detection circuit includes a current sampling resistor R2 and a differential amplifier OA1. This output current detection circuit is connected in series with the output circuit of the BUCK switching power supply main circuit. The differential amplifier OA1 amplifies the voltage difference generated across the current sampling resistor R2 and the current signal. To the MCU control unit; An output voltage detection circuit is electrically connected to the output terminal of the BUCK switching power supply main circuit. This output voltage detection circuit is used to detect the output voltage of the BUCK switching power supply main circuit in real time and output a voltage signal. To the MCU control unit; The switching transistor status detection circuit is electrically connected to the drive signal of the switching transistor or a control signal related to the switching transistor's status. This circuit is used to detect the operating status of the switching transistor in real time and output a switching transistor fault diagnosis signal. To the MCU control unit.

[0007] Specifically, the MCU control unit integrates a fault diagnosis algorithm. This algorithm is programmed to receive input voltage signals from various detection circuits. Temperature signal Output current signal Output voltage signal and switching transistor fault diagnosis signals Based on a preset threshold range, the fault diagnosis algorithm determines the power supply's operating status. When any parameter deviates from the normal threshold, the fault diagnosis algorithm triggers the corresponding protection mechanism, generates fault information, and reports it to the host computer via the communication module.

[0008] In the switching transistor temperature detection circuit, the NTC thermistor R0 and the voltage divider resistor R1 are connected in series to the DC power supply. The input voltage of the voltage divider resistor R1 is used as the temperature signal received by the ADC terminal of the MCU control unit. Temperature signal There is a mapping relationship between the actual temperature of the switching transistor and the actual temperature of the transistor. The MCU can perform accurate temperature conversion through a pre-stored lookup table.

[0009] Temperature signal voltage value With DC power supply voltage The resistance value of NTC thermistor RO The resistance value of voltage divider resistor R1 The following relationship must be satisfied: ; In the output current detection circuit, the current sampling resistor R2 is set to a low resistance value. Its function is to accurately convert the current signal flowing through the output circuit of the BUCK switching power supply main circuit into a measurable voltage signal, thereby providing input for the differential amplifier OA1.

[0010] The switching transistor state detection circuit includes a differentiator OA2 and a comparator OA3. The differentiator OA2 differentiates the drive signal or voltage signal related to the switching transistor's state. This differentiation effectively extracts the instantaneous change characteristics of the drive signal or voltage signal, thereby generating a differentiated output signal that reflects the dynamic response of the switching transistor. This differentiated output signal can capture fast transient events in the circuit.

[0011] A second aspect of the present invention provides a fault diagnosis method for a BUCK switching power supply based on intelligent monitoring, applied to the aforementioned fault diagnosis system for a BUCK switching power supply based on intelligent monitoring, comprising the following steps: The input voltage detection circuit detects the input voltage signal of the BUCK switching power supply main circuit in real time. The temperature signal is obtained by connecting the NTC thermistor R0 on the surface of the heat sink of the switching transistor in series with the voltage divider resistor R1. The output current signal is obtained through the current sampling resistor R2 and the differential amplifier OA1. The output voltage detection circuit detects the output voltage signal of the BUCK switching power supply main circuit in real time. ; The differentiator OA2 differentiates the drive signal of the switching transistor or the voltage signal related to the state of the switching transistor, and the comparator OA3 compares the output signal of the differentiator OA2 with a reference voltage to generate a switching transistor fault diagnosis signal. ; The input voltage signal acquired in real time as described above Temperature signal Output current signal and output voltage signal Set the predetermined threshold ranges respectively; Determine the input voltage signal Temperature signal Output current signal and output voltage signal Whether it falls outside its corresponding threshold range, or to determine the fault diagnosis signal of the switching transistor. The continuous level state; When any abnormal signal is detected, the system triggers the corresponding protection mechanism. At the same time, based on the characteristics of the abnormal signal, the specific fault type is identified, and the identified fault type information is sent to the host computer for display via a preset communication method, thereby realizing automated fault diagnosis, rapid response, and information reporting.

[0012] In summary, this application includes at least one of the following beneficial technical effects: 1. This invention utilizes the fault diagnosis algorithm built into the MCU control unit to trigger corresponding protection mechanisms based on the comparison results between the real-time detection signal and the threshold range. When the fault diagnosis signal of the switching transistor remains high and is judged to be a short circuit fault, the MCU can immediately cut off the input power of the BUCK switching power supply main circuit, thereby preventing the fault from spreading and ensuring the safety of the power supply and its connected downstream circuits.

[0013] 2. After the MCU control unit detects an anomaly and triggers the protection mechanism, it can send the fault information to the host computer for intuitive display through a preset communication method. This allows maintenance personnel to quickly understand the fault type and status without spending a lot of time on manual measurement and troubleshooting, thereby significantly shortening the fault location and recovery time and reducing maintenance costs.

[0014] 3. This invention provides multi-dimensional real-time monitoring of the operating status of the BUCK switching power supply through an input voltage detection circuit, a switching transistor temperature detection circuit, an output current detection circuit, an output voltage detection circuit, and a switching transistor status detection circuit. In the switching transistor temperature detection circuit, the NTC thermistor is directly mounted on the surface of the switching transistor's heatsink. The differentiator and comparator in the switching transistor status detection circuit can capture the instantaneous dynamic changes of the switching transistor, thereby enabling immediate diagnosis of rapid faults such as short circuits. Attached Figure Description

[0015] Figure 1 This is an architecture diagram of a BUCK switching power supply fault diagnosis system based on intelligent monitoring, as described in this application. Figure 2 This is a schematic diagram of the detection circuit of this application; Figure 3 This is a schematic diagram of the fault diagnosis process of this application. Detailed Implementation

[0016] The following is combined with Figure 1 -Appendix Figure 3 This application will be described in further detail below.

[0017] Please see the appendix Figure 1 , Figure 1 This is an architecture diagram of a BUCK switching power supply fault diagnosis system based on intelligent monitoring, according to an embodiment of the present invention. The present invention provides a BUCK switching power supply fault diagnosis system based on intelligent monitoring, comprising: The BUCK switching power supply main circuit includes one or more switching transistors, and its function is to convert and output electrical energy.

[0018] The MCU control unit is electrically connected to the main circuit of the BUCK switching power supply. The function of the MCU control unit is to generate pulse width modulation (PWM) signals to control the on and off of the main circuit of the BUCK switching power supply, perform data processing tasks, determine fault types, and perform data communication operations.

[0019] An input voltage detection circuit is electrically connected to the input terminal of the BUCK switching power supply main circuit. This input voltage detection circuit is used to detect the input voltage of the BUCK switching power supply main circuit in real time and convert it into an input voltage signal. The aforementioned It is output to the analog-to-digital converter (ADC) port of the MCU control unit.

[0020] The switching transistor temperature detection circuit includes an NTC thermistor R0 and a voltage divider resistor R1. The NTC thermistor R0 is directly mounted on the surface of the switching transistor's heatsink and fixed with thermally conductive silicone to accurately conduct and detect the switching transistor's temperature. The NTC thermistor R0 and the voltage divider resistor R1 are connected in series to a DC power supply (e.g., a 3.3V DC power supply). The input voltage of the voltage divider resistor R1 is used as the temperature signal. The output is sent to the ADC port of the MCU control unit.

[0021] The workflow of this system is as follows: Each detection circuit acquires key parameter information of the BUCK switching power supply main circuit in real time, including input voltage signals. Temperature signal Output current signal Output voltage signal and switching transistor fault diagnosis signals These signals are transmitted to the MCU control unit. The MCU control unit receives and processes these signals, and its internal fault diagnosis algorithm judges the signals according to a preset threshold range. When any signal deviates from its normal threshold range, the fault diagnosis algorithm identifies the specific fault type and triggers the corresponding protection mechanism (e.g., adjusting the PWM duty cycle or cutting off the input power). Simultaneously, the MCU control unit reports the generated fault information to the host computer via a preset communication method (e.g., Modbus bus). The host computer receives and displays the fault information, for example, displaying the corresponding operating condition in red, thereby achieving automated, rapid diagnosis, protection, and management of BUCK switching power supply faults.

[0022] A typical BUCK switching power supply main circuit consists of core components such as a switching transistor (e.g., MOSFET), a freewheeling diode, an energy storage inductor L0, and an output filter capacitor. When the MCU control unit outputs a PWM signal to turn on the switching transistor, the input voltage charges the inductor L0 through the switching transistor and supplies power to the load. When the switching transistor is turned off, the energy stored in the inductor L0 continues to supply power to the load through the freewheeling diode. Precise control of the output voltage is achieved by adjusting the duty cycle of the PWM signal.

[0023] The MCU control unit, as the central processing unit of this system, is responsible for receiving and processing analog signals from various detection circuits, and converting these signals into digital quantities through its built-in analog-to-digital converter (ADC). Its main functions include: generating PWM signals to drive the switching transistors of the BUCK power supply main circuit according to a preset control strategy; executing internally stored fault diagnosis algorithms to perform real-time analysis and judgment of the collected data; triggering corresponding protection mechanisms based on the diagnostic results when an anomaly is detected, such as adjusting the PWM duty cycle or cutting off the circuit input power; and exchanging data with the host computer through a preset communication interface (such as a serial communication port) to report system status and fault information. The MCU receives data through its ADC port. , , , Signals are received via GPIO ports. The signal controls the PWM output.

[0024] The input voltage detection circuit is used to monitor the input voltage of the BUCK switching power supply main circuit in real time. This circuit typically consists of a voltage divider network composed of two series resistors. The input voltage is proportionally attenuated through this network, converting a higher voltage into a voltage signal within the MCU's ADC input range. . The signal is then sent to the ADC port of the MCU control unit for sampling and quantization. By... Through monitoring, the MCU can determine whether there is an overvoltage or undervoltage state in the input power supply.

[0025] The switching transistor temperature detection circuit mainly consists of an NTC thermistor R0 and a voltage divider resistor R1. The NTC thermistor R0 is directly mounted on the surface of the heatsink of the switching transistor (e.g., MOSFET) and fixed with thermally conductive silicone to ensure that the NTC thermistor R0 can accurately sense the temperature change of the switching transistor in real time. The NTC thermistor R0 and the voltage divider resistor R1 are connected in series to a DC power supply (e.g., a 3.3V DC power supply). The resistance value of the NTC thermistor R0... The resistance decreases as temperature increases. Therefore, when the temperature of the switching transistor rises, the resistance of R0 decreases, causing the voltage at the voltage divider point to rise. This voltage at the voltage divider point is used as a temperature signal. The output is sent to the ADC port of the MCU control unit. The MCU uses a pre-stored mapping table or calculation formula to... The voltage value is converted into the actual switching transistor temperature.

[0026] For example, when the DC power supply voltage When the voltage is 3.3V and the voltage divider resistor R1 is 10kΩ: Under low temperature conditions, the resistance value of the NTC thermistor R0 The impedance is approximately 200 kΩ, at which point the temperature signal... The voltage value is: ; Under high temperature conditions, the resistance value of the NTC thermistor R0 The impedance is approximately 0.5 kΩ, at which point the temperature signal... The voltage value is: ; in, The voltage value representing the temperature signal; Indicates the DC power supply voltage; This indicates the resistance value of the NTC thermistor R0; This indicates the resistance value of the voltage divider resistor R1.

[0027] The output current detection circuit is used to monitor the output current of the BUCK switching power supply main circuit in real time. This circuit connects a low-resistance current sampling resistor R2 in series in the output loop. When the output current flows through R2, a small voltage difference proportional to the current magnitude is generated across it. Since this voltage difference is typically very small and insufficient to be directly recognized by the MCU's ADC port, a differential amplifier OA1 is introduced. The differential amplifier OA1 is used to accurately amplify the voltage difference across R2 and convert it into an output current signal with an amplitude within the MCU's ADC input range. The low-resistance current sampling resistor R2 is chosen to minimize the additional power loss introduced during current sensing and the voltage drop across the main circuit output voltage.

[0028] The output voltage detection circuit is used to monitor the output voltage of the BUCK switching power supply main circuit in real time. Similar to the input voltage detection circuit, this circuit also uses a resistor divider network (e.g., composed of voltage divider resistors R4). This voltage divider network proportionally attenuates the output voltage of the BUCK switching power supply, converting it into a voltage signal that can be recognized by the MCU ADC port. . The signal is sent to the MCU control unit for sampling. By... With continuous monitoring, the MCU can determine whether there are undervoltage, overvoltage, or abnormal ripple in the output voltage.

[0029] The switching transistor status detection circuit is used to detect the instantaneous operating status of the switching transistor in real time, especially for abnormal situations that may cause rapid circuit damage. This circuit mainly consists of a differentiator OA2 and a comparator OA3.

[0030] Differentiator OA2 differentiates the drive signal of the switching transistor or the voltage signal related to the state of the switching transistor (such as the drain-source voltage Vds or gate-source voltage Vgs). Differentiation can highlight the instantaneous change characteristics of the signal, such as the rapid rise or fall of the voltage, thereby generating a differentiated output signal that reflects the dynamic response of the switching transistor.

[0031] Comparator OA3 receives the differentiated output signal from differentiator OA2 and compares it with a preset reference voltage, the set value of which can be obtained from a resistor divider network. Determined, in the formula This is a reference voltage, the magnitude of which can be adjusted according to specific operating conditions to optimize detection sensitivity; , For resistance, A resistor connected to ground; For series connection with reference voltage and The resistance between, and Together they form a voltage divider circuit.

[0032] When the amplitude of the differential output signal exceeds the reference voltage threshold, comparator OA3 outputs a high level, forming a fault diagnosis signal for the switching transistor. Otherwise, output a low level. Switch fault diagnosis signal. The voltage level directly reflects the abnormal state of the switching transistor: when A continuous high level indicates a possible short circuit fault in the switching transistor; when A continuous low level may indicate an open-circuit fault in the switching transistor. The signal is sent to the digital input port of the MCU control unit.

[0033] See attached document Figure 2 , Figure 2 This is a schematic diagram of a detection circuit according to an embodiment of the present invention.

[0034] The MCU control unit synchronously and with high precision acquires analog signals from various detection circuits via its built-in analog-to-digital converter (ADC) channel: input voltage signal Temperature signal Output current signal and output voltage signal Meanwhile, the MCU's general purpose input / output (GPIO) ports continuously monitor switching transistor fault diagnosis signals. The level state. To improve the accuracy of data processing, the MCU can perform digital filtering on the data after receiving the ADC sampling data, such as moving average filtering, to eliminate noise interference that may exist during the acquisition process. Furthermore, for temperature signals... and output current signal The MCU will perform unit conversion based on the pre-stored mapping table or linear conversion formula, converting it into the actual temperature value (degrees Celsius) and current value (amperes).

[0035] In the fault diagnosis algorithm of the MCU control unit, predetermined threshold ranges are set for each key monitoring signal to define the normal operating state and the abnormal state. These thresholds are determined through experimental data and system design requirements.

[0036] Input voltage threshold: For input voltage signals Set upper limit threshold and lower threshold .when When it is determined to be an input overvoltage, when The system is judged to be undervoltage input.

[0037] Temperature threshold: for temperature signals Set an over-temperature protection threshold. For example, when The converted temperature value exceeds the threshold. When the temperature is too high, it is determined that the switching transistor is overheating.

[0038] Output current threshold: For output current signal Set an overcurrent protection threshold. .when The converted current value exceeds The time is judged as output overcurrent.

[0039] Output voltage threshold: For output voltage signal Set upper limit threshold and lower threshold .when When it is judged as output overvoltage, when The system is judged to be undervoltage at that time.

[0040] The MCU's fault diagnosis algorithm continuously compares the real-time acquired signal values ​​with corresponding thresholds. Any signal value exceeding its preset threshold range, or a switching transistor fault diagnosis signal, will trigger an error. A sustained abnormal voltage level is considered abnormal.

[0041] When the MCU's fault diagnosis algorithm detects an abnormal signal, the system will identify the specific fault type based on the type and duration of the abnormal signal and immediately trigger the corresponding protection mechanism.

[0042] Over-temperature protection: When the temperature signal... The corresponding switching transistor temperature reaches or exceeds the preset over-temperature threshold. At this time, the MCU control unit will adjust the duty cycle of the generated PWM signal. Specifically, the MCU will gradually or directly reduce the PWM duty cycle, thereby reducing the average current flowing through the switching transistor, reducing the power consumption of the switching transistor, and allowing its temperature to drop back to a safe range.

[0043] Input and output voltage abnormality and output overcurrent protection (non-short circuit): When the input voltage signal... Output voltage signal Or output current signal When the output exceeds its corresponding threshold range (but not involving a short circuit fault in the switching transistor), the MCU control unit attempts to stabilize the output by adjusting its PWM control algorithm. For example, when the output voltage is too low or the output current is too high, the MCU increases the PWM duty cycle to boost the output; when the output voltage is too high, the MCU decreases the PWM duty cycle to stabilize the output.

[0044] Switching transistor short-circuit fault protection: When the switching transistor fault diagnosis signal... When the high-level state is maintained continuously (e.g., for a duration exceeding a preset microsecond-level time threshold), the fault diagnosis algorithm determines that a short-circuit fault has occurred in the switching transistor. In this case, the MCU control unit will immediately trigger protection measures to cut off the input power supply to the BUCK switching power supply main circuit, such as by controlling a relay or turning off the upstream power supply MOSFET, to prevent the excessive current caused by the short circuit from causing permanent damage to the system or a safety accident. Open-circuit fault diagnosis of switching transistor: When the switching transistor fault diagnosis signal When the low-level state is maintained continuously (for example, for a duration exceeding a preset microsecond time threshold), the fault diagnosis algorithm determines that the switching transistor has an open-circuit fault. At this time, the power supply usually cannot work properly, and the MCU will report the open-circuit fault information of the switching transistor to the host computer.

[0045] After identifying a specific fault type and triggering the corresponding protection mechanism, the MCU control unit encapsulates the fault information and sends it to the host computer via a preset communication interface. This system uses the Modbus bus communication protocol to realize data interaction between the MCU and the host computer.

[0046] The communication mechanism supports two modes: Host computer polling mode: The host computer periodically requests system status data and fault information from the MCU by sending Modbus function code commands. After receiving the request, the MCU packages the current operating status, various detection values, and whether there is a fault into a data frame and replies to the host computer.

[0047] MCU Active Reporting Mode: When the MCU detects a major fault (such as a short circuit or overheating of the switching transistor), it will actively send a fault alarm message to the host computer after certain conditions are met (such as the fault duration reaching a preset value), ensuring the timeliness of the fault response.

[0048] See attached document Figure 3 , Figure 3 This is a schematic diagram of a fault diagnosis process according to an embodiment of the present invention. To further illustrate the collaborative working process of the technical solution of the present invention, a specific working scenario example will be used for explanation below.

[0049] Under normal operating conditions, the BUCK switching power supply main circuit receives the input voltage and drives the switching transistor to perform energy conversion through the PWM signal generated by the MCU control unit, outputting stable voltage and current.

[0050] Continuous monitoring: The input voltage detection circuit, the switching transistor temperature detection circuit, the output current detection circuit, and the output voltage detection circuit continuously acquire their respective parameters in real time and generate an input voltage signal. Temperature signal Output current signal and output voltage signal Meanwhile, the switching transistor status detection circuit continuously monitors the operating status of the switching transistor and outputs a switching transistor fault diagnosis signal. All these signals are transmitted in real time to the ADC port or GPIO port of the MCU control unit.

[0051] Data processing: The MCU control unit performs analog-to-digital conversion and digital filtering on the received analog signals, converting them into digital signals. and Converted into actual temperature and current values.

[0052] Status Assessment: The fault diagnosis algorithm continuously compares these real-time data with preset normal threshold ranges. Under normal operating conditions, all signal values ​​fall within their corresponding threshold ranges, and the switching transistor fault diagnosis signal... Maintaining a normal operating level. The MCU determines that the system is in normal operation.

[0053] Information reporting: The MCU control unit periodically encapsulates the current normal system status data (such as real-time voltage, current, temperature, etc.) and sends it to the host computer via the Modbus protocol. The operating status indicator area on the host computer display interface shows normal status and updates various real-time monitoring parameters.

[0054] During normal system operation, a short circuit fault suddenly occurred in the load of the BUCK switching power supply, causing a sharp increase in output current.

[0055] Fault signal acquisition: The voltage difference across the current sampling resistor R2 in the output current detection circuit increases rapidly. After being amplified by the differential amplifier OA1, the output current signal is obtained. The amplitude exceeded the preset overcurrent protection threshold. Meanwhile, due to the load short circuit, the output voltage signal output by the output voltage detection circuit... It may drop rapidly, falling below the preset output undervoltage threshold. The switching transistor may experience a rapid temperature rise due to overcurrent, causing the temperature signal to... Exceeding the over-temperature threshold In extreme cases, the switching transistor may also be damaged by a short-circuit impact, resulting in a fault diagnosis signal for the switching transistor. Continuous high level.

[0056] Fault type identification: The fault diagnosis algorithm of the MCU control unit receives these abnormal signals in real time. The algorithm first determines... This is identified as an output overcurrent fault. If If both occur simultaneously, it is further determined to be an output undervoltage fault. If If this is detected, it indicates that the switching transistor is overheating. More importantly, if a switching transistor fault diagnosis signal is detected... If the signal remains high, the fault diagnosis algorithm will identify it as a short circuit fault in the switching transistor.

[0057] Protection mechanism triggered: For output overcurrent / undervoltage (non-short circuit): The MCU control unit adjusts the duty cycle of the PWM signal according to a preset strategy. For example, if the output current is continuously too high but does not reach the level of a short circuit in the switching transistor, the MCU will gradually reduce the PWM duty cycle to limit the output current and avoid damage to the load and power supply.

[0058] To address the issue of overheating of the switching transistor: The MCU control unit gradually reduces the PWM duty cycle to decrease the power consumption of the switching transistor, causing its temperature to drop back to a safe range, thus achieving derating operation.

[0059] For short circuits in switching transistors: If the fault diagnosis algorithm determines that the fault is a short circuit in the switching transistor (i.e.) If a high-level signal persists for more than a microsecond-level time threshold, the MCU control unit will immediately execute the highest-priority protection action to cut off the input power supply to the BUCK switching power supply main circuit. This can be achieved by controlling a relay to disconnect the input power supply connection or turning off the preceding power supply MOSFET, thereby blocking the fault current path in a very short time and preventing permanent damage to the system.

[0060] Fault information reporting: When the protection mechanism is triggered, the MCU control unit will actively report the generated fault information (e.g., fault type code, occurrence timestamp, instantaneous value of related signal) to the host computer via the Modbus protocol.

[0061] Host Computer Display and Response: After receiving fault information, the host computer's display interface will switch the operating status indicator area from normal to fault (e.g., displayed in red), and the specific fault type, such as a short circuit in the switching transistor, will be displayed in the fault information area. Maintenance personnel can quickly identify the fault type through the host computer interface, thus guiding subsequent troubleshooting and repair work.

[0062] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A fault diagnosis system for a BUCK switching power supply based on intelligent monitoring, characterized in that, include: BUCK switching power supply main circuit, including switching transistors; The MCU control unit is electrically connected to the main circuit of the BUCK switching power supply and is used to generate PWM signals to control the operation of the main circuit of the BUCK switching power supply, process data, determine faults, and perform communication. An input voltage detection circuit is electrically connected to the input terminal of the BUCK switching power supply main circuit. It is used to detect the input voltage of the BUCK switching power supply main circuit in real time and output the input voltage signal to the MCU control unit. The switching transistor temperature detection circuit includes an NTC thermistor R0 and a voltage divider resistor R1. The NTC thermistor R0 is directly attached to the surface of the switching transistor heat sink and is used to detect the switching transistor temperature in real time and output a temperature signal to the MCU control unit. The output current detection circuit includes a current sampling resistor R2 and a differential amplifier, which are connected in series with the output circuit of the BUCK switching power supply main circuit. The differential amplifier is used to amplify the voltage difference across the current sampling resistor R2 and output the current signal to the MCU control unit. The output voltage detection circuit is electrically connected to the output terminal of the BUCK switching power supply main circuit, and is used to detect the output voltage of the BUCK switching power supply main circuit in real time and output the voltage signal to the MCU control unit. The switching transistor status detection circuit is electrically connected to the driving or related control signals of the switching transistor, and is used to detect the working status of the switching transistor in real time and output the switching transistor fault diagnosis signal to the MCU control unit.

2. The BUCK switching power supply fault diagnosis system based on intelligent monitoring according to claim 1, characterized in that, The MCU control unit includes a fault diagnosis algorithm, which is used to receive input voltage signal, temperature signal, output current signal, output voltage signal and switching transistor fault diagnosis signal, determine the power supply operating status according to a preset threshold range, and trigger a protection mechanism and report fault information when an abnormality is detected.

3. The BUCK switching power supply fault diagnosis system based on intelligent monitoring according to claim 1, characterized in that, The NTC thermistor R0 and the voltage divider resistor R1 are connected in series in a DC power supply, and the input voltage of the voltage divider resistor R1 serves as the temperature signal received by the ADC terminal of the MCU control unit.

4. The BUCK switching power supply fault diagnosis system based on intelligent monitoring according to claim 1, characterized in that, The temperature signal has a mapping relationship with the temperature of the switching transistor, and the voltage value of the temperature signal... DC power supply voltage The resistance value of NTC thermistor RO The resistance value of voltage divider resistor R1 The following relationship must be satisfied: 。 5. A fault diagnosis system for a BUCK switching power supply based on intelligent monitoring according to claim 1, characterized in that, The current sampling resistor R2 is a low-resistance resistor used to convert the current signal into a voltage signal in the output circuit of the BUCK switching power supply main circuit.

6. The BUCK switching power supply fault diagnosis system based on intelligent monitoring according to claim 1, characterized in that, The MCU control unit also adjusts the PWM duty cycle generated by the MCU control unit according to whether the temperature corresponding to the temperature signal reaches the preset temperature threshold, so as to perform over-temperature protection on the main circuit of the BUCK switching power supply.

7. A fault diagnosis system for a BUCK switching power supply based on intelligent monitoring according to claim 1, characterized in that, The switching transistor state detection circuit includes a differentiator and a comparator. The differentiator is used to differentiate the driving signal or voltage signal of the switching transistor and generate a differential output signal that reflects the dynamic response of the switching transistor by extracting the instantaneous change characteristics of the driving signal or voltage signal.

8. A fault diagnosis system for a BUCK switching power supply based on intelligent monitoring according to claim 7, characterized in that, The comparator is used to receive the differentiated output signal of the differentiator and compare the differentiated output signal with a reference voltage. By comparing the results, the fault diagnosis signal of the switching transistor is obtained, where... For reference voltage, , For resistance, A resistor connected to ground; For series connection with reference voltage and The resistance between, and Together they form a voltage divider circuit.

9. A fault diagnosis system for a BUCK switching power supply based on intelligent monitoring according to claim 8, characterized in that, The level of the switching transistor fault diagnosis signal reflects whether the switching transistor is in an abnormal state. When the switching transistor fault diagnosis signal is continuously high, the fault diagnosis algorithm determines that the switching transistor is short-circuited and triggers the MCU control unit to cut off the input power of the BUCK switching power supply main circuit.

10. A fault diagnosis method for a BUCK switching power supply based on intelligent monitoring, applied to the fault diagnosis system for a BUCK switching power supply based on intelligent monitoring as described in any one of claims 1-9, characterized in that, Includes the following steps: The voltage signal of the BUCK switching power supply main circuit is detected in real time by the input voltage detection circuit. The NTC thermistor R0 on the surface of the heat sink of the switching transistor is connected in series with the voltage divider resistor R1 to obtain the temperature signal. The current sampling resistor R2 and the differential amplifier obtain the output current signal. The output voltage detection circuit detects the voltage signal of the BUCK switching power supply main circuit in real time. The differentiator differentiates the drive signal of the switching transistor or the voltage signal related to the state of the switching transistor. The comparator compares the output signal of the differentiator with the reference voltage to generate a fault diagnosis signal for the switching transistor. Threshold ranges are set for the input voltage signal, temperature signal, output current signal, and output voltage signal respectively; Determine whether the input voltage signal, temperature signal, output current signal, and output voltage signal are outside their corresponding threshold ranges, or determine the continuous level state of the switching transistor fault diagnosis signal; When an abnormal signal is detected, the corresponding protection mechanism is triggered, and the specific fault type is identified based on the abnormal signal. The fault type is then sent to the host computer for display via communication.

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