High-power synchronous rectification direct-current power supply based on silicon carbide material and control method thereof

Abstract

The invention relates to the technical field of direct-current power supplies, in particular to a silicon carbide material-based high-power synchronous rectification direct-current power supply and a control method thereof, and the silicon carbide material-based high-power synchronous rectification direct-current power supply comprises an input filtering module, a high-frequency inversion module, a synchronous rectification module, an output filtering module and a control module; the output end of the high-frequency inversion module is connected with the input end of the synchronous rectification module, and the high-frequency inversion module is composed of a full-bridge inversion circuit composed of SiC MOSFETs. The output end of the synchronous rectification module is connected with the input end of the output filtering module, and the synchronous rectification module comprises a topological structure in which a SiC Schottky diode and a SiC MOSFET are connected in parallel; and the control module is in signal connection with the high-frequency inversion module and the synchronous rectification module, acquires input voltage, output voltage, current and temperature parameters in real time, and controls the on-off state of each module through a driving signal. The invention has the effects of effectively reducing the power supply energy loss and improving the power supply efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of DC power supplies, and in particular, to a high-power synchronous rectification DC power supply based on silicon carbide material and its control method. Background Art

[0002] With the rapid development of new energy power generation, fast charging of electric vehicles and other fields, as the core device for energy conversion, the performance of high-power DC power supplies directly affects the energy efficiency level in the new energy system and the field of electric vehicles. Traditional high-power DC power supplies generally use silicon-based power devices, such as IGBT, silicon-based MOSFET and asynchronous rectification technology.

[0003] Although these devices meet the application requirements to a certain extent, under extreme conditions such as high voltage, high frequency and high power, their performance bottlenecks gradually appear, such as large conduction losses, slow switching speed, poor thermal stability and other problems, which limit the further improvement of the efficiency and power density of DC power supplies. Therefore, there is room for improvement. Summary of the Invention

[0004] In order to effectively reduce the power energy loss and improve the power supply efficiency, the present application provides a high-power synchronous rectification DC power supply based on silicon carbide material and its control method.

[0005] In a first aspect, the present application provides a high-power synchronous rectification DC power supply based on silicon carbide material, adopting the following technical solution:

[0006] A high-power synchronous rectification DC power supply based on silicon carbide material includes an input filtering module, a high-frequency inversion module, a synchronous rectification module, an output filtering module and a control module;

[0007] The input end of the input filtering module is connected to an external DC power supply, and the output end is connected to the input end of the high-frequency inversion module;

[0008] The output end of the high-frequency inversion module is connected to the input end of the synchronous rectification module, and the high-frequency inversion module consists of a full-bridge inversion circuit composed of SiC MOSFETs;

[0009] The output end of the synchronous rectification module is connected to the input end of the output filtering module, and the synchronous rectification module includes a topological structure in which a SiC Schottky diode is connected in parallel with a SiC MOSFET;

[0010] The output end of the output filtering module is connected to a load, for providing stable DC electrical energy;

[0011] The control module is signal-connected to the high-frequency inversion module and the synchronous rectification module, and real-time collects input voltage, output voltage, current and temperature parameters, and controls the switching states of each module through drive signals.

[0012] By adopting the above technical solutions, a high-frequency inverter module and a synchronous rectification module are constructed by using SiC MOSFETs and SiC Schottky diodes, making full use of their excellent characteristics such as high bandgap width, high breakdown electric field strength, and low on-resistance, significantly improving the overall performance of the power supply. Compared with traditional silicon-based IGBTs, the application of SiC MOSFETs and SiC Schottky diodes not only reduces the on-state loss and switching loss of the devices but also increases the operating frequency and power density of the power supply. The high-frequency inverter module adopts a full-bridge inverter circuit composed of SiC MOSFETs, combined with the topology structure in which SiC Schottky diodes and SiC MOSFETs are connected in parallel in the synchronous rectification module, realizing the efficient conversion of DC electrical energy to DC electrical energy. This not only reduces the loss of energy during the conversion process but also improves the conversion efficiency and stability of the power supply, ensuring the precise control of the output voltage and current. The control module dynamically adjusts the PWM duty cycle by using an adaptive PID algorithm through real-time acquisition of the input voltage, current, and temperature parameters, and controls the switching states of each module through precise drive signals, realizing the dynamic regulation of the output voltage and current, and improving the adaptability and flexibility of the power supply.

[0013] Preferably, the high-frequency inverter module includes a full-bridge inverter circuit composed of four groups of SiC MOSFETs, whose gates are respectively connected to the drive signal output terminals of the control module; the input terminals of the full-bridge inverter circuit are connected in parallel with input filter capacitors, and the output terminals are connected in series with the primary winding of a high-frequency transformer, and the secondary winding is connected to the synchronous rectification module.

[0014] By adopting the above technical solutions, the full-bridge inverter circuit uses four groups of SiC MOSFETs, taking advantage of the high-frequency switching characteristics and low-loss advantages of SiC MOSFETs, making the inversion process more efficient and fast. Moreover, the DC input voltage is effectively smoothed by the input filter capacitors, reducing the influence of voltage fluctuations on the inverter circuit and improving the stability and reliability of the inversion process. As a key component for energy transmission, the ingenious connection between the primary winding and the secondary winding of the high-frequency transformer not only realizes electrical isolation but also meets the input voltage requirements of the synchronous rectification module by changing the voltage level, further enhancing the flexibility and adaptability of the entire power supply system, significantly improving the performance of the high-frequency inverter module, and laying a solid foundation for the efficient and stable operation of the entire DC power supply system.

[0015] Preferably, the synchronous rectification module includes that both ends of the secondary winding are respectively connected to two groups of synchronous rectification units, and each group of synchronous rectification units is composed of a SiC Schottky diode and a SiC MOSFET connected in reverse parallel; the gate of the SiC MOSFET is connected to the synchronous rectification drive terminal of the control module, and its source is commonly connected to the positive input terminal of the output filter module.

[0016] By adopting the above technical solution, the excellent performance of the SiC material is utilized, resulting in a significant reduction in the conduction loss and switching loss during the rectification process, thereby remarkably improving the rectification efficiency. The gate of the SiC MOSFET is connected to the synchronous rectification drive terminal of the control module, achieving precise control of the switching state of the rectification unit, ensuring the synchronization of the rectification process with the output waveform of the high-frequency inverter module, further reducing energy loss, greatly enhancing the rectification efficiency, and also enhancing the performance and stability of the entire DC power supply system.

[0017] Preferably, the control module includes an input parameter detection unit, an output parameter detection unit, a temperature sensor, a PWM signal generator, and a synchronous rectification drive unit; the input parameter detection unit is connected to the input terminal of the high-frequency inverter module, the output parameter detection unit is connected to the output terminal of the output filter module, and the temperature sensor is attached to the surface of the SiC MOSFET; the PWM signal generator generates the switching signal of the high-frequency inverter module according to the detected parameters, and the synchronous rectification drive unit controls the conduction timing of the SiC MOSFET according to the output current direction and phase.

[0018] By adopting the above technical solution, the input parameter detection unit and the output parameter detection unit respectively monitor the input and output states of the high-frequency inverter module in real time, providing accurate feedback data for the PWM signal generator, enabling it to dynamically adjust the switching signal of the high-frequency inverter module according to the real-time detected parameters, thereby optimizing the inverter efficiency and the stability of the output voltage. The temperature sensor is attached to the surface of the SiC MOSFET to monitor its operating temperature in real time, effectively preventing overheating and extending the service life of the device. The synchronous rectification drive unit precisely controls the conduction timing of the SiC MOSFET according to the direction and phase of the output current, ensuring the high efficiency and reliability of the synchronous rectification process and further improving the efficiency of the entire power supply system.

[0019] In a second aspect, the present application also provides a control method for a high-power synchronous rectification DC power supply based on silicon carbide material, adopting the following technical solution:

[0020] A control method for a high-power synchronous rectification DC power supply based on silicon carbide material, the control method for the high-power synchronous rectification DC power supply based on silicon carbide material includes the steps of:

[0021] Real-time monitor the input voltage of the input filter module, the output voltage of the output filter module, the load current, and the junction temperature of the SiC MOSFET;

[0022] Based on the difference between the output voltage and the preset target voltage, generate the PWM duty cycle of the high-frequency inverter module based on the PID algorithm, and dynamically adjust the PWM signal frequency;

[0023] Generate the driving signal of the SiC MOSFET in the synchronous rectification module based on the load current direction and the phase of the secondary side voltage of the high-frequency transformer, so that it conducts during the current freewheeling stage;

[0024] When it is detected that the load current is lower than the set threshold, switch to the discontinuous conduction mode and reduce the PWM frequency to reduce the switching loss.

[0025] By adopting the above technical solutions, by real-time monitoring the input voltage of the input filter module, the output voltage of the output filter module, the load current, and the junction temperature of the SiC MOSFET, the operating state of the power supply system can be grasped in real time, providing key data support for subsequent precise control. According to the difference between the output voltage and the preset target voltage, generate the PWM duty cycle of the high-frequency inverter module based on the PID algorithm, and dynamically adjust the PWM signal frequency, realizing precise control of the output voltage. The application of the PID algorithm enables the system to quickly respond to voltage fluctuations and maintain the stability of the output voltage. At the same time, dynamically adjusting the PWM frequency helps to further optimize the inverter efficiency and reduce harmonic interference. Generate the driving signal of the SiC MOSFET in the synchronous rectification module based on the load current direction and the phase of the secondary side voltage of the high-frequency transformer, so that it conducts during the current freewheeling stage, making use of the excellent performance of the SiC material to achieve the high efficiency and reliability of synchronous rectification. By precisely controlling the conduction timing of the SiC MOSFET, the energy loss during the rectification process is effectively reduced, and the rectification efficiency is improved. When it is detected that the load current is lower than the set threshold, switch to the discontinuous conduction mode and reduce the PWM frequency to reduce the switching loss. In the case of light load or no load, by adjusting the working mode and reducing the switching frequency, the standby power consumption and switching loss of the system are effectively reduced, further improving the overall efficiency, realizing the comprehensive optimization of the high-power synchronous rectification DC power supply based on silicon carbide materials, not only improving the efficiency and stability of the system, but also enhancing the adaptability and reliability of the system.

[0026] In a preferred example of the present application, it can be further configured as follows: According to the difference between the output voltage and the preset target voltage, generate the PWM duty cycle of the high-frequency inverter module based on the PID algorithm, and dynamically adjust the PWM signal duty cycle, specifically including:

[0027] Obtain the voltage error value according to the output voltage and the preset target voltage, input the voltage error value into the preset PID controller, and output the duty cycle increment;

[0028] According to the ratio of the input voltage to the output voltage, limit the maximum value of the duty cycle increment, obtain the adjusted duty cycle, and send the adjusted duty cycle to the PWM signal generator to update the driving waveform of the high-frequency inverter module.

[0029] By adopting the above technical solution, the voltage error value between the output voltage and the preset target voltage is used to capture the voltage fluctuation information in real time, providing an accurate input signal for subsequent PID control. The voltage error value is input into the PID controller, and the PID controller calculates the increment of the duty cycle according to the magnitude, direction and change trend of the error value, enabling the system to automatically adjust the duty cycle according to the error value to achieve fast stabilization and precise control of the output voltage. Considering the ratio relationship between the input voltage and the output voltage, the maximum value of the duty cycle increment is limited to avoid system instability or reduced efficiency caused by too large or too small duty cycle, ensuring that the duty cycle fluctuates within a reasonable range, guaranteeing both the stability of the system and the optimization of the inversion efficiency. The adjusted duty cycle is sent to the PWM signal generator to update the drive waveform of the high-frequency inversion module, realizing precise control of the output voltage and optimization of the inversion efficiency.

[0030] In a preferred example of the present application, it can be further configured as follows: Before obtaining the voltage error value according to the output voltage and the preset target voltage, inputting the voltage error value into a preset PID controller, and outputting the duty cycle increment, the control method of the high-power synchronous rectification DC power supply based on silicon carbide material further includes:

[0031] According to the junction temperature of the SiC MOSFET, when the junction temperature of the SiC MOSFET is greater than 100 °C, adjust the PID parameters;

[0032] Input the adjusted PID parameters into the PID controller to dynamically update the parameters of the PID controller.

[0033] By adopting the above technical solution, as the core device of the high-frequency inversion module and the synchronous rectification module, the junction temperature of the SiC MOSFET directly affects the on-resistance, switching loss and long-term reliability of the device. When it is detected that the junction temperature of the SiC MOSFET exceeds the preset threshold of 100 °C, the parameters of the PID controller, such as the proportional coefficient, integral coefficient and differential coefficient, are adjusted according to the preset rules or algorithms to optimize the control strategy to adapt to the change of the SiC MOSFET performance in the high-temperature environment, thereby ensuring the stability and efficiency of the system. Input the adjusted PID parameters into the PID controller to realize the dynamic update of the PID controller parameters, ensuring that the PID controller can adjust its control strategy in real time according to the actual junction temperature of the SiC MOSFET to adapt to different working environments and load conditions, improving the adaptability of the system to the thermal characteristics of the SiC MOSFET, and enhancing the stability and efficiency of the system under various working conditions.

[0034] In a preferred example, the present application can be further configured as follows: generating a driving signal for the SiC MOSFET in the synchronous rectification module based on the load current direction and the phase of the secondary side voltage of the high-frequency transformer, and making it conduct during the current freewheeling stage, specifically including:

[0035] Determining the current commutation time point through a zero-crossing detection circuit for the secondary side voltage of the high-frequency transformer;

[0036] Turning on the corresponding synchronous rectification MOSFET in advance before current commutation and adding a dead time to avoid shoot-through of the bridge arm;

[0037] When reverse current is detected, immediately turning off the currently conducting synchronous rectification MOSFET and triggering the freewheeling diode to conduct, and dynamically compensating the rise / fall time of the driving signal according to the junction temperature to reduce switching transient losses.

[0038] By adopting the above technical solution, the current commutation time point is accurately determined through the zero-crossing detection circuit for the secondary side voltage of the high-frequency transformer, which provides a basis for the precise control of the synchronous rectification MOSFET, ensures that the synchronous rectification module can make a rapid response at the critical moment when the load current direction changes, effectively avoids the additional losses caused by current commutation delay in the traditional rectification method, turns on the corresponding synchronous rectification MOSFET in advance before current commutation, and cleverly adds a dead time, which ensures that the MOSFET has enough time to smoothly transition to the conducting state and effectively avoids the risk of shoot-through of the bridge arm. The setting of the dead time is a key link in synchronous rectification control, which ensures that the upper and lower two MOSFETs on the same bridge arm do not conduct simultaneously, thus protecting the safe operation of the circuit. When reverse current is detected, immediately turning off the currently conducting synchronous rectification MOSFET and quickly triggering the freewheeling diode to conduct, realizing seamless switching of the current, ensuring the continuity of the rectification process, reducing the heat loss caused by the MOSFET being in the conducting state for a long time, further improving the rectification efficiency. By dynamically adjusting the rise / fall time of the driving signal, the switching transient process can be optimized, switching losses can be reduced, and at the same time, the stable operation of the SiC MOSFET at different junction temperatures can be ensured.

[0039] In a preferred example, the present application can be further configured as follows: when the detected load current is lower than the set threshold current, switching to the discontinuous conduction mode and reducing the PWM frequency to reduce switching losses, specifically including:

[0040] When the load current is lower than 10% of the set threshold current within a continuous time period, it is determined as a light load state, the PWM frequency is reduced, and the dead time is increased;

[0041] Turning off the MOSFET drive of the synchronous rectification module, allowing the SiC Schottky diode to freewheel, and switching the output filter inductor to the discontinuous operation mode;

[0042] When the load current rises back to 20% of the set threshold current, a soft start strategy is adopted to gradually restore the PWM frequency and synchronous rectifier drive.

[0043] By adopting the above technical solution, when the load current is lower than 10% of the set threshold current within a continuous period, the system intelligently determines it as a light load state. By reducing the PWM frequency, the system reduces the number of switching operations, thereby reducing switching losses and improving the overall efficiency. Increasing the dead time further avoids the risk of shoot-through of the bridge arm and protects the safe operation of the circuit. In the light load state, the system turns off the MOSFET drive of the synchronous rectifier module and instead uses the SiC Schottky diode for freewheeling, achieving seamless current switching and efficient freewheeling. The output filter inductor is switched to a discontinuous operation mode, further reducing the energy consumption and heat generation of the system and improving the stability and reliability of the power supply system. When the load current rises back to 20% of the set threshold current, the system adopts a soft start strategy, ensuring that the power supply system can smoothly transition when the load changes and avoiding impacts and instability phenomena caused by suddenly increasing the switching frequency and drive signals.

[0044] In a preferred example, the present application can be further configured as: the control method of the high-power synchronous rectifier DC power supply based on silicon carbide material further includes the steps of:

[0045] Determine the working mode of the synchronous rectifier DC power supply according to the load current and the set threshold current;

[0046] Based on the working mode of the synchronous rectifier DC power supply, dynamically adjust the PWM frequency and the number of switchings.

[0047] By adopting the above technical solution, the system can intelligently adjust the working mode and control strategy according to the real-time change of the load, realizing the efficient management and optimization of the power supply system. This not only improves the overall efficiency of the power supply system, reduces energy consumption, but also enhances the stability and reliability of the system, providing strong support for the design and application of high-performance and high-efficiency high-power synchronous rectifier DC power supplies, giving full play to the advantages of SiC MOSFETs in high-frequency and high-temperature environments, and further improving the performance and reliability of the power supply system.

[0048] In a preferred example, the present application can be further configured as: the control method of the high-power synchronous rectifier DC power supply based on silicon carbide material further includes a fault protection step:

[0049] When the input voltage exceeds the maximum allowable voltage or the output voltage exceeds the overvoltage threshold, turn off the drive signals of the high-frequency inverter module and the synchronous rectifier module;

[0050] When the junction temperature of the SiC MOSFET exceeds the safe temperature threshold, the output power is gradually reduced until the junction temperature of the SiC MOSFET is lower than the safe temperature threshold.

[0051] By adopting the above technical solution, when the input voltage exceeds the maximum allowable voltage or the output voltage exceeds the overvoltage threshold, the system responds quickly and shuts off the drive signals of the high-frequency inverter module and the synchronous rectification module, which can effectively avoid serious consequences such as circuit breakdown and component damage caused by excessive voltage, protect the core components of the power supply system, and ensure the safe operation of the system. When the junction temperature of the SiC MOSFET exceeds the safe temperature threshold, the system gradually reduces the output power. By dynamically adjusting the output power, the effective control of the junction temperature of the SiC MOSFET is realized. This not only avoids the thermal stress shock caused by sudden temperature drop, but also ensures the stable operation of the system in a high-temperature environment and extends the service life of the SiC MOSFET.

[0052] In summary, the present application includes at least one of the following beneficial technical effects:

[0053] 1. By using SiC MOSFETs and SiC Schottky diodes to construct the high-frequency inverter module and the synchronous rectification module, the excellent characteristics such as high bandgap width, high breakdown electric field strength, and low on-resistance are fully utilized, significantly improving the overall performance of the power supply. Compared with traditional silicon-based IGBTs, the application of SiC MOSFETs and SiC Schottky diodes not only reduces the on-state loss and switching loss of the devices, but also increases the operating frequency and power density of the power supply. The high-frequency inverter module adopts a full-bridge inverter circuit composed of SiC MOSFETs, combined with the topology structure of the SiC Schottky diode and the SiC MOSFET in parallel in the synchronous rectification module, realizing the efficient conversion of DC electrical energy to DC electrical energy. This not only reduces the loss of energy during the conversion process, but also improves the conversion efficiency and stability of the power supply, ensuring the precise control of the output voltage and current. The control module dynamically adjusts the PWM duty cycle by using the adaptive PID algorithm through real-time acquisition of the input voltage, current, and temperature parameters, and controls the switching states of each module through precise drive signals, realizing the dynamic regulation of the output voltage and current, and improving the adaptability and flexibility of the power supply;

[0054] 2. By the voltage error value between the output voltage and the preset target voltage, the information of voltage fluctuation is captured in real time, providing an accurate input signal for subsequent PID control. The voltage error value is input into the PID controller. The PID controller calculates the increment of the duty cycle according to the magnitude, direction and change trend of the error value, enabling the system to automatically adjust the duty cycle according to the error value to achieve fast stabilization and precise control of the output voltage. Considering the ratio relationship between the input voltage and the output voltage, the maximum value of the duty cycle increment is limited to avoid system instability or reduced efficiency caused by too large or too small duty cycle, ensuring that the duty cycle fluctuates within a reasonable range, which not only guarantees the stability of the system but also optimizes the inversion efficiency. The adjusted duty cycle is sent to the PWM signal generator to update the drive waveform of the high-frequency inversion module, realizing precise control of the output voltage and optimization of the inversion efficiency;

[0055] 3. As the core device of the high-frequency inversion module and the synchronous rectification module, the junction temperature of the SiC MOSFET directly affects the on-resistance, switching loss and long-term reliability of the device. When it is detected that the junction temperature of the SiC MOSFET exceeds the preset threshold of 100 °C, the parameters of the PID controller, such as the proportional coefficient, integral coefficient and differential coefficient, are adjusted according to the preset rules or algorithms to optimize the control strategy to adapt to the change of the SiC MOSFET performance in the high-temperature environment, thereby ensuring the stability and efficiency of the system. The adjusted PID parameters are input into the PID controller to realize the dynamic update of the PID controller parameters, ensuring that the PID controller can adjust its control strategy in real time according to the actual junction temperature of the SiC MOSFET to adapt to different working environments and load conditions, improving the adaptability of the system to the thermal characteristics of the SiC MOSFET and enhancing the stability and efficiency of the system under various working conditions;

[0056] 4. When the input voltage exceeds the maximum allowable voltage or the output voltage exceeds the overvoltage threshold, the system responds quickly and shuts off the drive signals of the high-frequency inversion module and the synchronous rectification module, which can effectively avoid serious consequences such as circuit breakdown and component damage caused by too high voltage, protecting the core components of the power supply system and ensuring the safe operation of the system. When the junction temperature of the SiC MOSFET exceeds the safety temperature threshold, the system gradually reduces the output power. By dynamically adjusting the output power, the effective control of the junction temperature of the SiC MOSFET is realized, which not only avoids the thermal stress shock caused by sudden temperature drop but also ensures the stable operation of the system in the high-temperature environment and prolongs the service life of the SiC MOSFET. Description of the Drawings

[0057] Figure 1 is the circuit module diagram of a high-power synchronous rectification DC power supply based on silicon carbide material in an embodiment of the present application;

[0058] Figure 2 It is a flowchart of a control method for a high-power synchronous rectification DC power supply based on silicon carbide material in an embodiment of the present application;

[0059] Figure 3 It is a flowchart for implementing step S20 in the control method for a high-power synchronous rectification DC power supply based on silicon carbide material in an embodiment of the present application;

[0060] Figure 4 It is another flowchart for implementing the control method for a high-power synchronous rectification DC power supply based on silicon carbide material in an embodiment of the present application;

[0061] Figure 5 It is a flowchart for implementing step S30 in the control method for a high-power synchronous rectification DC power supply based on silicon carbide material in an embodiment of the present application;

[0062] Figure 6 It is a flowchart for implementing step S40 in the control method for a high-power synchronous rectification DC power supply based on silicon carbide material in an embodiment of the present application;

[0063] Figure 7 It is a flowchart for implementing the multi-mode switching step in the control method for a high-power synchronous rectification DC power supply based on silicon carbide material in an embodiment of the present application;

[0064] Figure 8 It is a flowchart for implementing the fault protection step in the control method for a high-power synchronous rectification DC power supply based on silicon carbide material in an embodiment of the present application. Detailed implementation manners

[0065] The following further elaborates on the present application with reference to the accompanying drawings.

[0066] In one embodiment, as Figure 1 shown, the present application discloses a high-power synchronous rectification DC power supply based on silicon carbide material, including an input filtering module, a high-frequency inversion module, a synchronous rectification module, an output filtering module, and a control module.

[0067] The input end of the input filtering module is connected to an external DC power supply, and the output end is connected to the input end of the high-frequency inversion module. The output end of the high-frequency inversion module is connected to the input end of the synchronous rectification module. Moreover, the high-frequency inversion module consists of a full-bridge inversion circuit composed of SiC MOSFETs. The high-frequency inversion module includes a full-bridge inversion circuit composed of four groups of SiC MOSFETs, whose gates are respectively connected to the driving signal output end of the control module. The input ends of the full-bridge inversion circuit are connected in parallel with input filtering capacitors, and the output end is connected in series with the primary winding of a high-frequency transformer. The secondary winding is connected to the synchronous rectification module.

[0068] The output terminal of the synchronous rectification module is connected to the input terminal of the output filtering module. The synchronous rectification module includes a topology in which a SiC Schottky diode and a SiC MOSFET are connected in parallel. The synchronous rectification module includes two ends of a secondary winding respectively connected to two groups of synchronous rectification units. Each group of synchronous rectification units is composed of a SiC Schottky diode and a SiC MOSFET connected in reverse parallel. The gate of the SiC MOSFET is connected to the synchronous rectification driving terminal of the control module, and its source electrodes are commonly connected to the positive input terminal of the output filtering module.

[0069] The output terminal of the output filtering module is connected to a load, which is used to provide stable DC electrical energy. The control module is signal-connected to the high-frequency inversion module and the synchronous rectification module, and real-time collects input voltage, output voltage, current and temperature parameters, and controls the switching states of each module through driving signals. The control module includes an input parameter detection unit, an output parameter detection unit, a temperature sensor, a PWM signal generator and a synchronous rectification driving unit. The input parameter detection unit is connected to the input terminal of the high-frequency inversion module, the output parameter detection unit is connected to the output terminal of the output filtering module, the temperature sensor is attached to the surface of the SiC MOSFET, the PWM signal generator generates switching signals for the high-frequency inversion module according to the detected parameters, and the synchronous rectification driving unit controls the conduction timing of the SiC MOSFET according to the output current direction and phase.

[0070] In one embodiment, as Figure 2 shown, the present application discloses a control method for a high-power synchronous rectification DC power supply based on silicon carbide materials, which specifically includes the following steps:

[0071] S10: Real-time monitor the input voltage of the input filtering module, the output voltage of the output filtering module, the load current and the junction temperature of the SiC MOSFET.

[0072] Specifically, by real-time monitoring the input voltage of the input filtering module, the output voltage of the output filtering module, the load current and the junction temperature of the SiC MOSFET, the operating state of the power supply system can be mastered in real time, providing key data support for subsequent precise control.

[0073] S20: Based on the difference between the output voltage and a preset target voltage, generate the PWM duty cycle of the high-frequency inversion module based on the PID algorithm, and dynamically adjust the PWM signal frequency.

[0074] In one embodiment, as Figure 3 shown, based on the difference between the output voltage and a preset target voltage, generate the PWM duty cycle of the high-frequency inversion module based on the PID algorithm, and dynamically adjust the PWM signal duty cycle, which specifically includes:

[0075] S21: Obtain the voltage error value based on the output voltage and the preset target voltage, input the voltage error value into a preset PID controller, and output the duty cycle increment.

[0076] Specifically, through the voltage error value between the output voltage and the preset target voltage, the information of voltage fluctuation is captured in real time. The voltage error value is input into the PID controller, and the PID controller calculates the increment of the duty cycle according to the magnitude, direction, and change trend of the error value. :

[0077] , where is the output voltage error, 、 、 are PID parameters, which are used to respond to the instantaneous change of the voltage error, eliminate the steady-state error, and suppress the voltage fluctuation;

[0078] It enables the system to automatically adjust the duty cycle according to the error value, so as to achieve fast stabilization and precise control of the output voltage.

[0079] S22: Limit the maximum value of the duty cycle increment according to the ratio of the input voltage to the output voltage, obtain the adjusted duty cycle, send the adjusted duty cycle to the PWM signal generator, and update the drive waveform of the high-frequency inverter module.

[0080] Specifically, considering the ratio relationship between the input voltage and the output voltage, the maximum value of the duty cycle increment is limited, satisfying:

[0081] , to avoid system instability or efficiency reduction caused by too large or too small duty cycle, ensure that the duty cycle fluctuates within a reasonable range, which not only ensures the stability of the system but also optimizes the inverter efficiency. Send the adjusted duty cycle to the PWM signal generator, update the drive waveform of the high-frequency inverter module, and achieve precise control of the output voltage and optimization of the inverter efficiency.

[0082] In an embodiment, as Figure 4 shown, before obtaining the voltage error value based on the output voltage and the preset target voltage, inputting the voltage error value into a preset PID controller, and outputting the duty cycle increment, the control method of the high-power synchronous rectification DC power supply based on silicon carbide material further includes:

[0083] S201: According to the junction temperature of the SiC MOSFET, when the junction temperature of the SiC MOSFET is greater than 100 °C, adjust the PID parameters.

[0084] S202: Input the adjusted PID parameters into the PID controller to dynamically update the parameters of the PID controller.

[0085] Specifically, as the core device of the high-frequency inverter module and the synchronous rectification module, the junction temperature of the SiC MOSFET directly affects the on-resistance, switching loss, and long-term reliability of the device. When it is detected that the junction temperature of the SiC MOSFET exceeds the preset threshold of 100 °C, the parameters of the PID controller are adjusted according to the preset rules or algorithms:

[0086] ;

[0087] Optimize the control strategy to adapt to the performance changes of the SiC MOSFET in a high-temperature environment, thereby ensuring the stability and efficiency of the system. Input the adjusted PID parameters into the PID controller to achieve dynamic update of the PID controller parameters, ensuring that the PID controller can adjust its control strategy in real time according to the actual junction temperature of the SiC MOSFET to adapt to different working environments and load conditions, improving the system's adaptability to the thermal characteristics of the SiC MOSFET, and enhancing the stability and efficiency of the system under various working conditions.

[0088] S30: Generate the drive signal of the SiC MOSFET in the synchronous rectification module based on the load current direction and the phase of the secondary-side voltage of the high-frequency transformer, so that it conducts during the current freewheeling stage.

[0089] In one embodiment, as Figure 5 shown, step S30, that is, generating the drive signal of the SiC MOSFET in the synchronous rectification module based on the load current direction and the phase of the secondary-side voltage of the high-frequency transformer, so that it conducts during the current freewheeling stage, specifically includes:

[0090] S31: Determine the current commutation time point through the zero-crossing detection circuit of the secondary-side voltage of the high-frequency transformer.

[0091] S32: Turn on the corresponding synchronous rectification MOSFET in advance before the current commutation and add a dead time to avoid shoot-through of the bridge arm.

[0092] S33: When the reverse current is detected, immediately turn off the currently conducting synchronous rectification MOSFET and trigger the conduction of the freewheeling diode, and dynamically compensate the rise / fall time of the drive signal according to the junction temperature to reduce the switching transient loss.

[0093] Specifically, the zero-crossing detection circuit of the secondary side voltage of the high-frequency transformer accurately determines the current commutation time point, providing a basis for the precise control of the synchronous rectification MOSFET, ensuring that the synchronous rectification module can respond quickly at the critical moment when the load current direction changes, effectively avoiding the additional losses caused by current commutation delay in the traditional rectification method. The corresponding synchronous rectification MOSFET is turned on in advance before current commutation, and a dead time is cleverly added to ensure that the MOSFET has enough time to smoothly transition to the conduction state and effectively avoid the risk of shoot-through of the bridge arm. The setting of the dead time is a key link in synchronous rectification control, which ensures that the upper and lower two MOSFETs on the same bridge arm will not conduct simultaneously, thus protecting the safe operation of the circuit. When the reverse current is detected, the currently conducting synchronous rectification MOSFET is immediately turned off, and the freewheeling diode is quickly triggered to conduct, realizing seamless switching of the current, ensuring the continuity of the rectification process, and also reducing the thermal losses generated by the MOSFET being in the conduction state for a long time, further improving the rectification efficiency. By dynamically adjusting the rise / fall time of the drive signal, the switching transient process can be optimized, reducing the switching losses while ensuring the stable operation of the SiC MOSFET at different junction temperatures.

[0094] S40: Generate a patient risk level based on the diabetes prediction result, and generate a personalized prevention plan according to the patient risk level in combination with the patient's basic information.

[0095] In one embodiment, as Figure 6 shown, step S40 is that when the detected load current is lower than the set threshold current, it switches to the discontinuous conduction mode and reduces the PWM frequency to reduce the switching losses, specifically including:

[0096] S41: When the load current is lower than 10% of the set threshold current within a continuous time period, it is determined to be in the light load state, the PWM frequency is reduced, and the dead time is increased.

[0097] S42: Turn off the MOSFET drive of the synchronous rectification module, and the SiC Schottky diode conducts freewheeling, and the output filter inductor is switched to the discontinuous working mode.

[0098] S43: When the load current rises back to 20% of the set threshold current, a soft start strategy is adopted to gradually restore the PWM frequency and the synchronous rectification drive.

[0099] Specifically, when the load current is lower than 10% of the set threshold current within a duration, the system intelligently determines it as a light load state. By reducing the PWM frequency, the system reduces the number of switching operations, thereby reducing switching losses and improving the overall efficiency. Increasing the dead time further avoids the risk of shoot-through of the bridge arm and protects the safe operation of the circuit. In the light load state, the system turns off the MOSFET drive of the synchronous rectification module and instead uses the SiC Schottky diode for freewheeling, achieving seamless current switching and efficient freewheeling. The output filter inductor is switched to a discontinuous operation mode, further reducing the energy consumption and heat generation of the system and improving the stability and reliability of the power supply system. When the load current rises back to 20% of the set threshold current, the system adopts a soft start strategy to ensure a smooth transition of the power supply system during load changes and avoid impacts and instability phenomena caused by sudden increases in the switching frequency and drive signals.

[0100] In this embodiment, by real-time monitoring of the input voltage of the input filter module, the output voltage of the output filter module, the load current, and the junction temperature of the SiC MOSFET, the operating state of the power supply system can be grasped in real time, providing key data support for subsequent precise control. According to the difference between the output voltage and the preset target voltage, the PWM duty cycle of the high-frequency inverter module is generated based on the PID algorithm, and the PWM signal frequency is dynamically adjusted to achieve precise control of the output voltage. The application of the PID algorithm enables the system to quickly respond to voltage fluctuations and maintain the stability of the output voltage. At the same time, dynamically adjusting the PWM frequency helps to further optimize the inverter efficiency and reduce harmonic interference. The drive signal of the SiC MOSFET in the synchronous rectification module is generated based on the load current direction and the secondary side voltage phase of the high-frequency transformer, making it conduct during the current freewheeling stage. Utilizing the excellent performance of the SiC material, the high efficiency and reliability of synchronous rectification are achieved. By precisely controlling the conduction timing of the SiC MOSFET, the energy loss during the rectification process is effectively reduced, and the rectification efficiency is improved. When the detected load current is lower than the set threshold, it is switched to a discontinuous conduction mode and the PWM frequency is reduced to reduce switching losses. In the light load or no-load condition, by adjusting the working mode and reducing the switching frequency, the standby power consumption and switching losses of the system are effectively reduced, further improving the overall efficiency, and achieving a comprehensive optimization of the high-power synchronous rectification DC power supply based on silicon carbide material. This not only improves the efficiency and stability of the system but also enhances the adaptability and reliability of the system.

[0101] In one embodiment, as Figure 7 shown, the control method of the high-power synchronous rectification DC power supply based on silicon carbide material further includes a multi-mode switching step:

[0102] S50: Determine the working mode of the synchronous rectification DC power supply according to the load current and the set threshold current.

[0103] S60: Dynamically adjust the PWM frequency and the number of switching times based on the operating mode of the synchronous rectification DC power supply.

[0104] Specifically, in the heavy load (load current > 80% of the set threshold current), the continuous conduction mode (CCM) is adopted, and the fixed PWM frequency is 200 kHz. In the medium load (20% ≤ load current ≤ 80%), it switches to the boundary conduction mode (BCM), and the PWM frequency (80 - 200 kHz) is dynamically adjusted according to the load current. In the light load (load current < 20%), pulse frequency modulation (PFM) is enabled, and the number of switching times is reduced by skip cycle control.

[0105] In one embodiment, as Figure 8 shown, the control method of the high-power synchronous rectification DC power supply based on silicon carbide material further includes a fault protection step:

[0106] S70: When the input voltage exceeds the maximum allowable voltage or the output voltage exceeds the overvoltage threshold, turn off the drive signals of the high-frequency inverter module and the synchronous rectification module.

[0107] Specifically, when the input voltage exceeds the maximum allowable voltage or the output voltage exceeds the overvoltage threshold, the system responds quickly, turns off the drive signals of the high-frequency inverter module and the synchronous rectification module, which can effectively avoid serious consequences such as circuit breakdown and component damage caused by excessive voltage, protect the core components of the power supply system, and ensure the safe operation of the system.

[0108] S80: When the junction temperature of the SiC MOSFET exceeds the safe temperature threshold, gradually reduce the output power until the junction temperature of the SiC MOSFET is lower than the safe temperature threshold.

[0109] Specifically, when the junction temperature of the SiC MOSFET exceeds the safe temperature threshold, the system gradually reduces the output power. By dynamically adjusting the output power, effective control of the junction temperature of the SiC MOSFET is achieved. It not only avoids the thermal stress shock caused by sudden temperature drop but also ensures the stable operation of the system in a high-temperature environment and extends the service life of the SiC MOSFET.

[0110] It should be understood that the magnitudes of the sequence numbers of the steps in the above embodiments do not mean the order of execution. The order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0111] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included within the protection scope of the present application.

Claims

1. A high-power synchronous rectification DC power supply based on silicon carbide material, characterized in that: It includes an input filter module, a high-frequency inverter module, a synchronous rectification module, an output filter module and a control module; The input end of the input filter module is connected to an external DC power supply, and the output end is connected to the input end of the high-frequency inverter module; The output end of the high-frequency inverter module is connected to the input end of the synchronous rectification module, and the high-frequency inverter module is composed of a full-bridge inverter circuit composed of SiCMOSFET; The output end of the synchronous rectification module is connected to the input end of the output filtering module, and the synchronous rectification module includes a topological structure in which a SiC Schottky diode and a SiC MOSFET are connected in parallel; The output end of the output filter module is connected to a load to provide stable direct current power; The control module is connected to the high-frequency inverter module and the synchronous rectification module by signals, collects input voltage, output voltage, current and temperature parameters in real time, and controls the switch state of each module through a driving signal.

2. The high-power synchronous rectification DC power supply based on silicon carbide material according to claim 1, characterized in that: The high-frequency inverter module includes a full-bridge inverter circuit composed of four groups of SiC MOSFETs, whose gates are respectively connected to the drive signal output ends of the control module; the input end of the full-bridge inverter circuit is connected in parallel with an input filter capacitor, the output end is connected in series with the primary winding of the high-frequency transformer, and the secondary winding is connected to the synchronous rectification module.

3. The high-power synchronous rectification DC power supply based on silicon carbide material according to claim 1, characterized in that: The synchronous rectification module includes two groups of synchronous rectification units connected to the two ends of the secondary winding, each group of synchronous rectification units is composed of a SiC Schottky diode and a SiC MOSFET connected in reverse parallel; the gate of the SiC MOSFET is connected to the synchronous rectification drive end of the control module, and the source thereof is commonly connected to the positive input end of the output filter module.

4. The high-power synchronous rectification DC power supply based on silicon carbide material according to claim 1, characterized in that: The control module includes an input parameter detection unit, an output parameter detection unit, a temperature sensor, a PWM signal generator and a synchronous rectification drive unit; the input parameter detection unit is connected to the input end of the high-frequency inverter module, the output parameter detection unit is connected to the output end of the output filter module, and the temperature sensor is attached to the surface of the SiC MOSFET; the PWM signal generator generates a switching signal of the high-frequency inverter module according to the detection parameters, and the synchronous rectification drive unit controls the conduction timing of the SiC MOSFET according to the output current direction and phase.

5. A control method for a high-power synchronous rectification DC power supply based on silicon carbide material as claimed in any one of claims 1 to 4, characterized in that: The control method of the high-power synchronous rectification DC power supply based on silicon carbide material comprises the following steps: Real-time monitoring of the input voltage of the input filter module, the output voltage of the output filter module, the load current and the junction temperature of the SiCMOSFET; According to the difference between the output voltage and the preset target voltage, the PWM duty cycle of the high-frequency inverter module is generated based on the PID algorithm, and the PWM signal frequency is dynamically adjusted; Based on the load current direction and the secondary voltage phase of the high-frequency transformer, a drive signal for the SiC MOSFET in the synchronous rectification module is generated to turn it on during the current freewheeling phase. When it is detected that the load current is lower than the set threshold, it switches to discontinuous conduction mode and reduces the PWM frequency to reduce switching losses.

6. The control method of a high-power synchronous rectification DC power supply based on silicon carbide material according to claim 5, characterized in that: The method generates the PWM duty cycle of the high-frequency inverter module based on the PID algorithm according to the difference between the output voltage and the preset target voltage, and dynamically adjusts the PWM signal duty cycle, specifically including: Obtaining a voltage error value according to the output voltage and a preset target voltage, inputting the voltage error value into a preset PID controller, and outputting a duty cycle increment; According to the ratio of input voltage to output voltage, the maximum value of duty cycle increment is limited to obtain the adjusted duty cycle, which is sent to the PWM signal generator to update the driving waveform of the high-frequency inverter module.

7. The control method of a high-power synchronous rectification DC power supply based on silicon carbide material according to claim 5, characterized in that: Before obtaining a voltage error value according to the output voltage and a preset target voltage, inputting the voltage error value into a preset PID controller, and outputting a duty cycle increment, the control method of a high-power synchronous rectification DC power supply based on silicon carbide material further includes: According to a junction temperature of the SiC MOSFET, when the junction temperature of the SiC MOSFET is greater than 100° C., adjusting a PID parameter; The adjusted PID parameters are input into the PID controller to dynamically update the parameters of the PID controller.

8. The control method of a high-power synchronous rectification DC power supply based on silicon carbide material according to claim 5, characterized in that: The method of generating a driving signal of the SiCMOSFET in the synchronous rectification module based on the load current direction and the secondary voltage phase of the high-frequency transformer to turn it on in the current freewheeling stage specifically includes: The current commutation time point is determined by the high-frequency transformer secondary side voltage zero-crossing detection circuit; The corresponding synchronous rectifier MOSFET is turned on in advance before current commutation, and a dead time is added to avoid direct conduction of the bridge arm; When reverse current is detected, the currently turned-on synchronous rectification MOSFET is immediately turned off, and the freewheeling diode is triggered to turn on, dynamically compensating the rise / fall time of the drive signal according to the junction temperature to reduce switching transient losses.

9. The control method of a high-power synchronous rectification DC power supply based on silicon carbide material according to claim 5, characterized in that: When it is detected that the load current is lower than the set threshold current, switching to the discontinuous conduction mode and reducing the PWM frequency to reduce the switching loss specifically includes: When the load current is lower than 10% of the set threshold current for a sustained period of time, it is judged as a light load state, the PWM frequency is reduced, and the dead time is increased; Turn off the MOSFET driver of the synchronous rectifier module, let the SiC Schottky diode continue the current, and switch the output filter inductor to the discontinuous working mode; When the load current rises back to 20% of the set threshold current, a soft start strategy is adopted to gradually restore the PWM frequency and synchronous rectification drive.

10. The control method of a high-power synchronous rectification DC power supply based on silicon carbide material according to claim 5, characterized in that: The control method of the high-power synchronous rectification DC power supply based on silicon carbide material also includes a fault protection step: When the input voltage exceeds the maximum allowable voltage or the output voltage exceeds the overvoltage threshold, the drive signals of the high-frequency inverter module and the synchronous rectification module are turned off; When the junction temperature of the SiC MOSFET exceeds a safety temperature threshold, the output power is reduced step by step until the junction temperature of the SiC MOSFET is lower than the safety temperature threshold.

Images