A zero-crossing processing method based on a boost circuit

Abstract

The application relates to the technical field of electronic circuits, in particular to a zero-crossing processing method based on a BOOST circuit, which comprises the following steps: setting a zero-crossing processing area according to an input voltage, wherein the zero-crossing processing area comprises a voltage threshold set, and the zero-crossing processing area is divided into multiple zero-crossing detection intervals based on the voltage threshold set and a zero-point current value; collecting a voltage value output by an input voltage sensor in real time, and judging whether the voltage value is in the voltage threshold set; if the voltage value is in the voltage threshold set, collecting an output current value detected by a current sensor in real time; comparing the output current value with the zero-point current value, so as to determine a zero-crossing detection interval corresponding to the output current value, and setting a corresponding detection duty cycle based on the zero-crossing detection interval. The application can accurately identify voltage zero-crossing points.

Description

Technical Field

[0001] This application relates to the technical field of electronic circuits, and in particular to a zero-crossing processing method based on a BOOST circuit. Background Technology

[0002] In the field of modern power electronics, where efficient, precise, and flexible control of the voltage, frequency, phase, or waveform of alternating current is required, and where stringent requirements are placed on the system's size, weight, reliability, and lifespan, AC-AC boost circuit topologies are often used to achieve the ultimate pursuit of system efficiency, reliability, power density (size / weight), and cost.

[0003] like Figure 1 As shown, based on the BOOST type AC-AC boost circuit topology, inductor L1 is the input filter inductor, A1 is the input current sensor, V1 is the input voltage sensor, L is the energy storage inductor, C1 is the input filter capacitor, and Q37, Q34, Q40, and Q31 are switching transistors. The first transmitting transistor refers to switching transistors Q40 and Q31, and the second transmitting transistor refers to switching transistors Q37 and Q34. L2 is the output filter inductor, C2 is the output filter capacitor, A2 is the output current sensor, V2 is the output voltage sensor, and K1 is a relay. The BOOST boost principle is that when the circuit Q37 and Q40 are turned on to UN, the energy storage inductor L stores energy. When Q37 and Q40 are turned off and Q34 and Q31 are turned on, the energy is released to the output terminal, achieving the purpose of boosting the voltage.

[0004] like Figure 2 To specify the specific operating mode of the switching transistors for the BOOST current, during the positive half-cycle of the voltage, the first transmitting transistor operates in complementary PWM mode, meaning that transistors Q40 and Q31 form a complementary bridge. The second transmitting transistor operates in turn-on mode to reduce losses caused by the diode voltage drop in the circuit. When Q40 is on, the energy storage inductor L stores energy; when Q40 is off, the energy from the energy storage inductor is output to the output terminal via Q34 and Q31. The process is similar during the negative half-cycle of the voltage: the first transmitting transistor operates in turn-on mode, and the second transmitting transistor operates in complementary PWM mode, meaning that transistors Q37 and Q34 form a complementary bridge.

[0005] Currently, due to voltage glitches, voltage distortion, and voltage sampling circuit delay issues, the software cannot accurately identify the voltage zero-crossing point, which leads to the risk of a shoot-through failure due to the incorrect timing of the transmitter tube being turned on near the zero-crossing point. Summary of the Invention

[0006] In order to accurately identify the voltage zero-crossing point, this application provides a zero-crossing processing method based on a BOOST circuit.

[0007] This application provides a zero-crossing processing method based on a BOOST circuit, employing the following technical solution:

[0008] A zero-crossing processing method based on a BOOST circuit includes the following steps:

[0009] A zero-crossing processing region is set according to the input voltage, and the zero-crossing processing region includes a set of voltage thresholds. The zero-crossing processing region is divided into multiple zero-crossing detection intervals based on the set of voltage thresholds and the zero-point current value.

[0010] The voltage value output by the input voltage sensor is acquired in real time, and it is determined whether the voltage value is within the voltage threshold set.

[0011] If the voltage value is within the voltage threshold set, the output current value detected by the current sensor is collected in real time.

[0012] The output current value is compared with the zero-point current value to determine the zero-crossing detection interval corresponding to the current output current value, and the corresponding detection duty cycle is set based on the zero-crossing detection interval.

[0013] By adopting the above technical solution, the zero-crossing dynamic adjustment strategy can minimize output voltage distortion. Traditional PWM modulation may cause current discontinuity due to dead time or commutation delay, leading to output voltage waveform distortion (such as steps or oscillations). By dynamically adjusting the duty cycle through current polarity detection, it is ensured that the current always has a low-impedance path (MOSFET or body diode). During the dead time (Td) inserted between complementary bridges, the body diode is used for freewheeling to avoid voltage spikes caused by inductor current interruption. Even if a MOSFET on one side is turned off, the current can still freewheel through the body diode of the complementary bridge, avoiding voltage spikes caused by inductor open circuit. During the commutation gap, the current naturally freewheels through the body diode, reducing MOSFET hard switching losses and voltage stress.

[0014] In one embodiment, the voltage threshold set includes a first voltage threshold and a second voltage threshold. Determining whether the voltage value falls within the voltage threshold set includes the following steps:

[0015] The voltage value is compared with the first voltage threshold and the second voltage threshold.

[0016] If the voltage value is greater than the first voltage threshold and less than the second voltage threshold, then the voltage value is determined to be within the voltage threshold set.

[0017] In one embodiment, the zero-crossing detection interval includes a negative zero-crossing interval and a positive zero-crossing interval. The zero-crossing processing region is divided into multiple zero-crossing detection intervals based on the voltage threshold set and the zero-point current value, including the following steps:

[0018] The horizontal axis region corresponding to the first voltage threshold and the zero-point current value is taken as the negative zero-crossing interval.

[0019] The horizontal axis region corresponding to the second voltage threshold and the zero-point current value is taken as the positive zero-crossing interval.

[0020] Both the negative zero-crossing interval and the positive zero-crossing interval are used as zero-crossing detection intervals.

[0021] In one embodiment, comparing the output current value with the zero-point current value to determine the zero-crossing detection interval corresponding to the current output current value includes the following steps:

[0022] The current output current value is compared with the zero-point current value, and it is determined whether the output current value is greater than the zero-point current value.

[0023] If the output current value is greater than the zero-point current value, then the current output current value is determined to be in the positive zero-point interval.

[0024] If the output current value is less than the zero-point current value, then the current output current value is determined to be in the negative zero-crossing interval.

[0025] In one embodiment, setting a corresponding detection duty cycle based on the zero-crossing detection interval includes the following steps:

[0026] If the current output current value is determined to be in the negative zero-crossing range, then the detection duty cycle of the first transmitting tube is set to... And the detection duty cycle of the second wave transmitter is set to .

[0027] If the current output current value is determined to be within the positive zero-crossing range, then the detection duty cycle of the first transmitting tube is set to... And the detection duty cycle of the second wave transmitter is set to .

[0028] in, Characterized by the duty cycle of a single switching transistor's waveform. Td is the time window during which both switches are turned off when they are in complementary states. This is the period of a complete PWM signal wave.

[0029] In one embodiment, the method for obtaining the duty cycle of the switching transistor includes the following steps:

[0030] The real-time voltage value output by the voltage sensor is acquired, and the effective value of the output voltage is calculated based on the real-time voltage value.

[0031] A voltage error value is generated based on the target output voltage and the current effective value of the output voltage, and the duty cycle of the switching transistor is determined based on the voltage error value.

[0032] In one embodiment, where the first voltage threshold is less than the second voltage threshold, comparing the voltage value with both the first and second voltage thresholds further includes the following steps:

[0033] When the voltage value is greater than the sum of the second voltage threshold and the voltage hysteresis voltage, the first transmitting tube is set to complementary mode and the second transmitting tube is set to conduction mode.

[0034] When the voltage value is less than the difference between the first voltage threshold and the voltage hysteresis voltage, the first transmitting tube is set to the conduction mode and the second transmitting tube is set to the complementary mode.

[0035] In one embodiment, determining the switching transistor's ripple duty cycle based on the voltage error value includes the following steps:

[0036] A control signal is generated based on the historical cumulative error and the current voltage error, and a PWM wave is generated based on the control signal.

[0037] The corresponding switching transistor's waveform duty cycle is determined by comparing the PWM waveform with a preset waveform, and the switching transistor is turned on or off based on the waveform duty cycle.

[0038] In one embodiment, the negative zero-crossing interval includes intervals t1, t2, and t3. After determining that the current output current value is within the negative zero-crossing interval, the following steps are also included:

[0039] Determine whether the current output current value is within the negative zero interval set.

[0040] When the current output current value is within the t1 range, the switching transistors Q31 and Q34 are turned on, and the current flows through the switching transistors Q31 and Q34 to the energy storage inductor.

[0041] When the current output current value is within the t2 range, the switch Q31 is turned on and the switch Q34 is turned off, and the current flows through the body diode of the switch Q34 to the energy storage inductor.

[0042] When the current output current value is within the t3 range, the switch Q31 is turned off, the switch Q37 is turned on, and the current flows through the body diode of the switch Q40 and the MOSFET of the switch Q37 to the energy storage inductor.

[0043] In one embodiment, the positive zero-crossing interval includes intervals t4, t5, and t6. After determining that the current output current value is within the positive zero-crossing interval, the following steps are further included:

[0044] Determine whether the current output current value is within the set of positive zero intervals.

[0045] When the current output current value is within the t4 range, the MOSFET of switch Q34 is turned on, and the current flows from the energy storage inductor through the MOSFET of switch Q34 and the body diode of switch Q31 to the output terminal.

[0046] When the current output current value is within the t5 range, the MOSFET of switch Q40 is turned on, the MOSFET of switch Q34 is turned off, and the current flows from the energy storage inductor through the body diode of switch Q37 and the MOSFET of switch Q40 to the UN terminal.

[0047] When the current output current value is within the t6 range, the MOSFETs of switching transistors Q40 and Q37 are turned on, and the current flows from the energy storage inductor through the MOSFETs of Q37 and Q40 to the UN terminal.

[0048] In summary, this application includes at least one of the following beneficial technical effects:

[0049] Zero-crossing dynamic adjustment strategy minimizes output voltage distortion. Traditional PWM modulation may cause current discontinuity due to dead time or commutation delay, leading to output voltage waveform distortion (such as steps or oscillations). Dynamic adjustment of the duty cycle through current polarity detection ensures that the current always has a low-impedance path (MOSFET or body diode). During the dead time (Td) inserted between complementary bridges, the body diode freewheels, avoiding voltage spikes caused by inductor current interruption. Even if a MOSFET on one side is turned off, the current can still freewheel through the body diode of the complementary bridge, avoiding voltage spikes caused by inductor open circuits. Natural freewheeling through the body diode during commutation gaps reduces MOSFET hard-switching losses and voltage stress. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of a BOOST-type AC-AC boost circuit topology.

[0051] Figure 2 This is a schematic diagram showing the specific operating mode of the switching transistor for BOOST current.

[0052] Figure 3 This is a block diagram of a zero-crossing processing method based on a BOOST circuit provided in an embodiment of this application.

[0053] Figure 4 This embodiment provides a schematic diagram of the operation of the current switching transistor.

[0054] Figure 5 This is an example Figure 4 Enlarged view of the zero-crossing processing region in the image.

[0055] Figure 6 This is the definition diagram of the zero-crossing processing region extension provided in this embodiment. Detailed Implementation

[0056] To better understand the purpose, technical solutions, and advantages of this application, it has been described and illustrated below with reference to the accompanying drawings and embodiments. However, those skilled in the art should understand that this application can be implemented without these details. In some cases, to avoid obscuring various aspects of this application due to unnecessary description, well-known methods, processes, systems, components, and / or circuits already described at a higher level will not be elaborated upon. It will be apparent to those skilled in the art that various modifications can be made to the embodiments disclosed in this application, and the general principles defined in this application can be applied to other embodiments and application scenarios without departing from the principles and scope of this application. Therefore, this application is not limited to the illustrated embodiments, but conforms to the broadest scope consistent with the scope of protection claimed in this application.

[0057] Reference Figure 1 This application discloses a zero-crossing processing method based on a BOOST circuit, which is applied to a zero-crossing processing circuit based on a BOOST circuit. The method includes an input detection module, a switch control module, and an output detection module. The input detection module is used to detect the input current and the input voltage. The switch control module is used to control the conduction or shutdown of the zero-crossing processing circuit. The output detection module is used to detect the output voltage and the output current.

[0058] Specifically, the input detection module includes an input current sensor A1, an input voltage sensor V1, an input filter inductor L1, and a relay k1. One end of the input voltage sensor V1 is connected to the power supply, and the other end is grounded. The input current sensor A1, the input filter inductor L1, and the relay k1 are connected in series, with one end connected to the power supply and the other end connected to one end of the energy storage inductor L of the switch control module.

[0059] The switching control module includes an energy storage inductor L, switching transistors Q37, Q34, Q40, and Q31. Switches Q37 and Q40 are connected in series, as are Q34 and Q31. The series-connected switches Q37 and Q40 are connected to the other end of the energy storage inductor L. The other end of the series-connected switches Q37 and Q40 is grounded, and the other end of the series-connected switches Q34 and Q31 is connected to the output filter inductor L2 of the output detection module.

[0060] The output detection module includes an output filter inductor L2, an output current sensor A2, an output voltage sensor V2, and a relay k1. One end of the output voltage sensor V2 is connected to the high-voltage terminal of the output, and the other end is connected to the low-voltage terminal of the output. The output filter inductor L2, the output current sensor A2, and the relay k1 are connected in series, with one end connected to the switch control module and the other end connected to the high-voltage terminal of the output.

[0061] It should be noted that the zero-crossing processing circuit based on the BOOST circuit also includes capacitors C1 and C2. One end of capacitor C1 is connected to the connection point between the input detection module and the switch control module, while the other end of capacitor C1 is grounded. One end of capacitor C2 is connected to the connection point between the switch control module and the output detection module, and the other end of capacitor C2 is grounded.

[0062] The aforementioned zero-crossing processing circuit based on the BOOST circuit is used to perform zero-crossing detection according to the zero-crossing processing method based on the BOOST circuit disclosed in this application. The BOOST boost control is divided into three intervals for separate control: the positive half-cycle interval, the negative half-cycle interval, and the zero-crossing interval, as follows: Figure 2 As shown, during the positive half-cycle, switches Q40 and Q31 operate in complementary PWM mode, with the output voltage duty cycle obtained from the PI closed-loop regulation. Q37 and Q34 are in conduction mode. During the negative half-cycle, switches Q40 and Q31 are in conduction mode, while Q37 and Q34 operate in complementary PWM mode, with the same duty cycle as the positive half-cycle duty cycle. To prevent inaccurate zero-crossing identification, [the following is omitted]. Figure 2 The voltage zero-crossing point is used to delineate a certain region as the zero-crossing processing region, such as... Figure 4 As shown, by setting input voltage setpoints A and B, and designating the interval between A and B as the zero-crossing processing region, switching transistors Q40 and Q31 form complementary PWM within this interval, while Q37 and Q34 also form complementary PWM modes, but with different duty cycles for the two complementary bridges. This ensures that there is no shoot-through risk near the voltage zero-crossing point due to incorrect transistor switching. This method does not rely on BOOST boost topology parameters, is simple to implement in engineering, and has good portability.

[0063] like Figure 3 As shown, the zero-crossing processing method based on the BOOST circuit includes the following steps:

[0064] S100 sets a zero-crossing processing region based on the input voltage, and the zero-crossing processing region includes a set of voltage thresholds. Based on the set of voltage thresholds and the zero-point current value, the zero-crossing processing region is divided into multiple zero-crossing detection intervals.

[0065] Among them, the zero-crossing processing area refers to Figure 4The voltage threshold set for the region between midpoint A and point B includes a first voltage threshold and a second voltage threshold. It should be noted that the first voltage threshold is... Figure 4 The voltage value corresponding to midpoint A, and the second voltage threshold is... Figure 4 The voltage value corresponding to midpoint B. The first voltage threshold is set to... The second voltage threshold is set to .

[0066] Furthermore, the zero-crossing detection interval includes a negative zero-crossing interval and a positive zero-crossing interval. Based on the voltage threshold set and the zero-point current value, the zero-crossing processing region is divided into multiple zero-crossing detection intervals, including the following steps:

[0067] S110, the horizontal axis region corresponding to the first voltage threshold and the zero-point current value is taken as the negative zero-crossing interval.

[0068] S120, the horizontal axis region corresponding to the second voltage threshold and the zero-point current value is taken as the positive zero-crossing interval.

[0069] S130 uses both the negative zero-crossing interval and the positive zero-crossing interval as the zero-crossing detection interval.

[0070] The zero-point current value refers to the current being zero, as referenced. Figure 6 X1 and X2 are positive zero-crossing intervals, and Y1 and Y2 are negative zero-crossing intervals.

[0071] S200 acquires the voltage value output by the input voltage sensor in real time and determines whether the voltage value is within the voltage threshold set.

[0072] Here, the voltage value refers to the voltage value detected by the input voltage sensor V1. The voltage value Uin is compared with the two endpoints of a voltage threshold set to determine whether the voltage value falls within the voltage threshold set. The voltage threshold set includes a first voltage threshold and a second voltage threshold. Determining whether the voltage value falls within the voltage threshold set includes the following steps:

[0073] S210, compare the voltage value with the first voltage threshold and the second voltage threshold.

[0074] S220, when the voltage value is greater than the first voltage threshold and less than the second voltage threshold, it is determined that the voltage value is within the voltage threshold set.

[0075] Specifically, when Uin> And Uin< The control range corresponding to the current voltage value is in the zero-crossing processing region.

[0076] S300: If the voltage value is within the voltage threshold set, the output current value detected by the current sensor will be collected in real time.

[0077] S400 compares the output current value with the zero-point current value to determine the zero-crossing detection interval corresponding to the current output current value, and sets the corresponding detection duty cycle based on the zero-crossing detection interval.

[0078] Specifically, when the voltage value is within the voltage threshold set, the output current value is detected in real time by the output current sensor A2, and the output current value is compared with the zero-point current value to determine the zero-crossing detection interval corresponding to the current value.

[0079] In one embodiment, the output current value is compared with the zero-crossing current value to determine the zero-crossing detection interval corresponding to the current output current value, including the following steps:

[0080] S410 compares the current output current value with the zero-point current value and determines whether the output current value is greater than the zero-point current value.

[0081] S420: If the output current value is greater than the zero-point current value, it is determined that the current output current value is in the positive zero-point interval.

[0082] S430: If the output current value is less than the zero-point current value, it is determined that the current output current value is in the negative zero-crossing interval.

[0083] Reference Figure 5 and Figure 6 In Uin> And Uin< This voltage range is considered the zero-crossing processing range. The output current is detected in real time by the output current sensor A2. Within this voltage range, if the current is less than zero, it is considered a negative zero-crossing range; if the current is greater than zero, it is considered a positive zero-crossing range.

[0084] In one embodiment, setting a corresponding detection duty cycle based on the zero-crossing detection interval includes the following steps:

[0085] S440, if the current output current value is determined to be in the negative zero-crossing range, then the detection duty cycle of the first transmitting tube is set to... And the detection duty cycle of the second wave transmitter is set to .

[0086] S450, if the current output current value is determined to be in the positive zero-crossing range, then the detection duty cycle of the first transmitting tube is set to... And the detection duty cycle of the second wave transmitter is set to .

[0087] in, Characterized by the duty cycle of a single switching transistor's waveform. Td is the time window during which both switches are turned off when they are in complementary states. This is the period of a complete PWM signal wave.

[0088] like Figure 5 As shown, during the negative zero-crossing interval, the detection duty cycle of switches Q40 and Q31 is... The detection duty cycle of switching transistors Q37 and Q34 is During the positive zero-crossing interval, the detection duty cycle of switching transistors Q40 and Q31 is: The detection duty cycle of switching transistors Q37 and Q34 is .

[0089] like Figure 5 The amplified section shows that Td is the time window during which both switches are turned off when they are in complementary states. This is the period of a complete PWM signal wave.

[0090] In one embodiment, the method for obtaining the duty cycle of the switching transistor includes the following steps:

[0091] S441 acquires the real-time voltage value output by the voltage sensor and calculates the effective value of the output voltage based on the real-time voltage value.

[0092] S442 generates a voltage error value based on the target output voltage and the current effective value of the output voltage, and determines the ripple duty cycle of the switching transistor based on the voltage error value.

[0093] The real-time output voltage is obtained through the output voltage sensor V2. ,formula Calculate the effective value of the output voltage, where n is the number of voltage samples obtained in one cycle. Compare the target output voltage with the current effective value of the output voltage. The difference is obtained by taking Uerr, and Uerr is used to obtain the duty cycle (Duty) of the switching transistor by taking the PI converter.

[0094] In one embodiment, where the first voltage threshold is less than the second voltage threshold, comparing the voltage value with both the first and second voltage thresholds further includes the following steps:

[0095] S211, when the voltage value is greater than the sum of the second voltage threshold and the voltage hysteresis voltage, the first transmitting tube is set to complementary mode and the second transmitting tube is set to conduction mode.

[0096] S212, when the voltage value is less than the difference between the first voltage threshold and the voltage hysteresis voltage, the first transmitting tube is set to the conduction mode and the second transmitting tube is set to the complementary mode.

[0097] It should be noted here that voltage thresholds are set for points A and B, with the voltage threshold at point A set as follows: The voltage threshold at point B is The input voltage Uin is detected by the input voltage sensor V1. When Uin is greater than... When +△U, the PWM mode of the transmitting transistors Q40 and Q31 is set to complementary, with a transmitting duty cycle of Duty. Q37 and Q34 are in conduction mode. During this positive half-cycle, when Q40 is high (i.e., its MOSFET is on), the energy storage inductor conducts to UN, increasing the inductor current. When Q40's MOSFET is off, but Q31 is not on (i.e., during the dead time), the energy storage inductor current flows through Q34's MOSFET and Q31's body diode. When Q31's MOSFET is on, the energy storage inductor current flows through Q31's MOSFET, reducing losses caused by diode voltage drop. When Uin is less than... When -ΔU occurs, Q40 and Q31 are set to conduction mode, while Q37 and Q34 are set to complementary PWM mode, with a waveform duty cycle of "Duty". Here, ΔU is the hysteresis voltage, and the waveform generation strategy within the hysteresis interval is the same as the previous moment. During this negative half-cycle, when Q37 is high (i.e., its MOSFET is on), the energy storage inductor conducts to UN, increasing its current. When Q37's MOSFET is off, but Q34 is not on (i.e., during the dead time), the energy storage inductor current flows through the body diode of Q34 and the MOSFET of Q31. When Q34 is on, the energy storage inductor current flows through its MOSFET, reducing losses caused by diode voltage drop.

[0098] In one embodiment, determining the switching transistor's ripple duty cycle based on the voltage error value includes the following steps:

[0099] S442-1 generates a control signal based on historical accumulated error and current voltage error, and generates a PWM wave based on the control signal.

[0100] S442-2 compares the PWM wave with the preset wave to determine the corresponding switching transistor's waveform duty cycle, and controls the switching transistor to turn on or off based on the waveform duty cycle.

[0101] In one embodiment, the negative zero-crossing interval includes intervals t1, t2, and t3. After determining that the current output current value is within the negative zero-crossing interval, the following steps are also included:

[0102] S510 determines whether the current output current value is within the negative zero interval set.

[0103] S520: When the current output current value is within the t1 range, switching transistors Q31 and Q34 are turned on, and the current flows through switching transistors Q31 and Q34 to the energy storage inductor.

[0104] When the current output current value is within the t2 range, switch Q31 is turned on and switch Q34 is turned off, and the current flows to the energy storage inductor through the body diode of switch Q34.

[0105] When the current output current value is within the t3 range, switch Q31 is turned off and switch Q37 is turned on. The current flows through the body diode of switch Q40 and the MOSFET of switch Q37 to the energy storage inductor.

[0106] In one embodiment, the positive zero-crossing interval includes intervals t4, t5, and t6. After determining that the current output current value is within the positive zero-crossing interval, the following steps are also included:

[0107] S610 determines whether the current output current value is within the positive zero interval set.

[0108] S620: When the current output current value is within the t4 range, the MOSFET of switch Q34 is turned on, and the current flows from the energy storage inductor through the MOSFET of switch Q34 and the body diode of switch Q31 to the output terminal.

[0109] S630: When the current output current value is within the t5 range, the MOSFET of switch Q40 is turned on and the MOSFET of switch Q34 is turned off. The current flows from the energy storage inductor through the body diode of switch Q37 and the MOSFET of switch Q40 to the UN terminal.

[0110] S640, when the current output current value is within the t6 range, the MOSFETs of switching transistors Q40 and Q37 are turned on, and the current flows from the energy storage inductor through the MOSFETs of Q37 and Q40 to the UN terminal.

[0111] Specifically, in interval t1: MOSFETs Q31 and Q34 are on, and the current is negative. The current flows through MOSFETs Q31 and Q34 to the energy storage inductor. In interval t2: MOSFET Q31 is on, and MOSFET Q34 is off. Because the current is negative, the current flows through the body diode of Q34 to the energy storage inductor. In interval t3: MOSFET Q31 is off, and MOSFET Q37 is on. The current flows from UN through the body diode of Q40 and MOSFET Q37 to the energy storage inductor. The other operating segments within the negative zero-crossing interval are similar, ensuring no uncircuited current flow and minimizing output voltage waveform distortion. In interval t4: MOSFET Q34 is on, and the current is positive. The current flows from the energy storage inductor through MOSFET Q34 and the body diode of Q31 to the output terminal. In the t5 interval: MOSFET Q40 is on, and MOSFET Q34 is off. Since the current is positive, it flows from the energy storage inductor through the body diode of Q37 and the MOSFET of Q40 to the UN terminal. In the t6 interval: MOSFETs Q40 and Q37 are on. The current flow direction is the same as in the t5 interval, except that the current flow direction changes from the body diode of Q37 to the MOSFET of Q37. The other operating segments within the positive zero-crossing interval are similar. This ensures that there is no unreturning current and minimizes the distortion of the output voltage waveform.

[0112] In another embodiment, a four-layer architecture of "hardware sampling + FPGA real-time judgment + intelligent driving + cloud monitoring" is adopted, with each layer working together to achieve precise current range control. When the current is in the negative zero-crossing range, special control logic is triggered to avoid increased losses caused by frequent switching of the switching transistor. Specifically, the FPGA receives the digital current value output from the sampling layer, which uses a 12-bit ADC with a sampling rate of 10kHz.

[0113] For example, the digitized current value is compared in parallel with preset thresholds, which are a negative zero threshold ±0.5A, a threshold of >0.5A for interval t1, a threshold of ∈ [-2A, -0.5A] for interval t2, and a threshold of <-2A for interval t3. The interval determination result is output with a determination delay ≤1μs to ensure that the switching action is synchronized with the current interval change.

[0114] A threshold self-calibration mechanism is designed to automatically correct interval thresholds by periodically collecting current data during stable system operation (e.g., dynamically adjusting the thresholds of intervals t2 and t3 by ±5% when inductor parameters drift due to changes in ambient temperature), improving the adaptability of interval determination. Multi-interval dynamic determination technology is adopted to overcome the limitations of traditional fixed threshold determination. Through FPGA parallel logic and adaptive threshold adjustment, real-time and accurate identification of the negative zero point, t1, t2, and t3 intervals is achieved, adapting to current changes under different operating conditions. Simultaneously, a switching transistor collaborative drive strategy is implemented, designing differentiated drive logic for different intervals. For example, in interval t2, a Q34 body diode is used for conduction, while in interval t3, a Q40 body diode and a Q37 MOSFET are combined, ensuring current flow while reducing switching transistor losses (15% lower than traditional solutions). A cloud-edge collaborative protection mechanism is adopted, combining local FPGA real-time control with cloud remote monitoring to achieve fault early warning, self-healing, and full lifecycle management, improving system reliability (mean time between failures (MTBF) is increased to 50,000 hours).

[0115] In another embodiment, based on the original experimental platform, a simulated load (0-10Ω adjustable) and a body diode temperature acquisition module (thermocouple sensor, accuracy ±1℃) are added at the UN terminal to simulate different load conditions in the t4-t6 range. Combining the system output characteristics, the positive zero-point range is set to "output current value ∈ [0A, 0.6A]" (partially overlapping with the negative zero-point range [-0.5A, 0.5A], where the overlapping area [0A, 0.5A] triggers priority logic), to accurately identify the critical state where the current turns from negative to positive, avoiding output voltage fluctuations.

[0116] Based on the existing Hall sensor, a new signal conditioning channel is added to specifically amplify the weak current signal (0-0.6A) in the positive zero-point range (amplification factor increased to 5 times), ensuring a sampling resolution of 0.01A within this range to meet the requirements for accurate judgment. Four new judgment channels are added to the existing FPGA logic, executing in parallel with the original range judgment. The judgment process is optimized as follows:

[0117] Step 1: Receive the dual-channel conditioned current signal (original channel + positive zero point dedicated channel).

[0118] Step 2: Process overlapping areas through the "interval priority determination" logic (e.g., [0A, 0.5A] belongs to both the negative zero point and positive zero point intervals, and is preferentially determined to be the positive zero point interval to avoid control conflicts).

[0119] Step 3: Output the 8-channel interval determination results (original 4 channels + 4 newly added channels), and the total determination delay remains ≤1μs.

[0120] Based on the requirements of the extended range, the switching control logic for the t4-t6 range was added, and the action strategy for the positive zero point range was improved.

[0121] Drive circuit expansion: To meet the high current requirements in the t4-t6 range, the original drive chip (ISO7740) has been upgraded to a dual-channel isolated drive chip (ISO7760), increasing the peak drive current to 4A and supporting synchronous high-speed conduction of Q37 and Q40. At the same time, an overcurrent protection pin has been added, which can directly acquire the current signal of the switching transistor and achieve overcurrent turn-off within 1μs.

[0122] Body diode protection optimization: In the scenario where the body diode of Q31 is conducting in the t4 interval and the body diode of Q37 is conducting in the t5 interval, a reverse recovery current suppression circuit (with a small-value non-inductive resistor of 0.1Ω in series) is added to reduce the reverse recovery loss of the body diode and improve system efficiency (efficiency is improved by 2%-3% in the t4 interval).

[0123] Precise identification technology for positive and negative zero points: Through a dedicated signal conditioning channel and priority judgment logic, high-precision identification of the positive and negative zero point range (0A-0.6A) is achieved, solving the control conflict problem in the overlapping area of ​​positive and negative zero points, and controlling the output voltage fluctuation within ±0.5%.

[0124] t6 interval dual-transistor synchronous drive technology: adopts dual-channel isolated drive chip and synchronous timing control logic to ensure that the conduction time difference between Q37 and Q40 is ≤0.5μs, avoids single-transistor overload under high current, and reduces the failure rate of switching transistors in the t6 interval by 40%.

[0125] Body diode loss suppression scheme: By connecting a non-inductive resistor in series with a reverse recovery current suppression circuit, the conduction loss of the body diode in the t4 and t5 intervals is effectively reduced, and the overall system efficiency is improved by 1.5%-2.5%.

[0126] The implementation principle is as follows:

[0127] set up Figure 5 The voltage thresholds at points A and B are given, with the voltage threshold at point A set to [value missing]. The voltage threshold at point B is The input voltage Uin is detected by the input voltage sensor V1. When Uin > And Uin< This voltage range is considered the zero-crossing processing range. The output current is monitored in real time by the output current sensor A2. Within this voltage range, if the current is less than zero, it is considered a negative zero-crossing range; if the current is greater than zero, it is considered a positive zero-crossing range. In the negative zero-crossing range, the waveform duty cycle of switches Q40 and Q31 is Duty - Δduty, and the waveform duty cycle of switches Q37 and Q34 is Duty + Δduty. In the positive zero-crossing range, the waveform duty cycle of switches Q40 and Q31 is Duty + Δduty, and the waveform duty cycle of switches Q37 and Q34 is Duty - Δduty.

[0128] It should be understood that although the steps in the flowcharts in the accompanying drawings are shown sequentially as indicated by the arrows, these steps are not necessarily performed in the order indicated by the arrows. Unless otherwise expressly stated herein, there is no strict order in which these steps are performed, and they may be performed in other orders.

[0129] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A zero-crossing processing method based on a BOOST circuit, characterized in that, The BOOST circuit includes a switch control module, which includes an energy storage inductor L, switching transistors Q37, Q34, Q40, and Q31. Switches Q37 and Q40 are connected in series, and switches Q34 and Q31 are connected in series. The series-connected switches Q37 and Q40 are connected to the other end of the energy storage inductor L. The other end of the series-connected switches Q37 and Q40 is grounded, and the other end of the series-connected switches Q34 and Q31 is connected to the output filter inductor of the output detection module. The first transmitting transistor refers to switches Q40 and Q31, and the second transmitting transistor refers to switches Q37 and Q34. The method includes the following steps: A zero-crossing processing region is set according to the input voltage, and the zero-crossing processing region includes a voltage threshold set, which includes a first voltage threshold and a second voltage threshold. Based on the voltage threshold set and the zero-point current value, the zero-crossing processing region is divided into multiple zero-crossing detection intervals. Specifically, the range between the first voltage threshold and the zero-point current value is taken as the negative zero-crossing interval, the range between the second voltage threshold and the zero-point current value is taken as the positive zero-crossing interval, and both the negative zero-crossing interval and the positive zero-crossing interval are taken as zero-crossing detection intervals. The voltage value output by the input voltage sensor is acquired in real time. When the voltage value is greater than the first voltage threshold and less than the second voltage threshold, it is determined that the voltage value is within the voltage threshold set, and the output current value detected by the current sensor is acquired in real time. The output current value is compared with the zero-point current value to determine the zero-crossing detection interval corresponding to the current output current value, and the corresponding detection duty cycle is set based on the zero-crossing detection interval. If the current output current value is determined to be in the negative zero-crossing range, then the detection duty cycle of the first transmitting tube is set. And the detection duty cycle of the second wave transmitter is set to ; If the current output current value is determined to be within the positive zero-crossing range, then the detection duty cycle of the first transmitting tube is set to... And the detection duty cycle of the second wave transmitter is set to ; in, Characterized by the duty cycle of a single switching transistor's waveform. Td is the time window during which both switches are turned off when they are in complementary states. This is the period of a complete PWM signal wave.

2. The zero-crossing processing method based on the BOOST circuit according to claim 1, characterized in that, The output current value is compared with the zero-point current value to determine the zero-crossing detection interval corresponding to the current output current value, including the following steps: The current output current value is compared with the zero-point current value, and it is determined whether the output current value is greater than the zero-point current value. If the output current value is greater than the zero-point current value, then the current output current value is determined to be in the positive zero-crossing interval. If the output current value is less than the zero-point current value, then the current output current value is determined to be in the negative zero-crossing interval.

3. The zero-crossing processing method based on the BOOST circuit according to claim 1, characterized in that, The method for obtaining the duty cycle of the switching transistor includes the following steps: Collect the real-time voltage value output by the voltage sensor, and calculate the effective value of the output voltage based on the real-time voltage value; A voltage error value is generated based on the target output voltage and the current effective value of the output voltage, and the duty cycle of the switching transistor is determined based on the voltage error value.

4. The zero-crossing processing method based on the BOOST circuit according to claim 1, characterized in that, The first voltage threshold is less than the second voltage threshold. Comparing the voltage value with the first voltage threshold and the second voltage threshold further includes the following steps: When the voltage value is greater than the sum of the second voltage threshold and the voltage hysteresis voltage, the first transmitter is set to complementary mode and the second transmitter is set to conduction mode. When the voltage value is less than the difference between the first voltage threshold and the voltage hysteresis voltage, the first transmitting tube is set to the conduction mode and the second transmitting tube is set to the complementary mode.

5. The zero-crossing processing method based on the BOOST circuit according to claim 3, characterized in that, Determining the duty cycle of the switching transistor based on the voltage error value includes the following steps: A control signal is generated based on the historical cumulative error and the current voltage error, and a PWM wave is generated based on the control signal; The corresponding switching transistor's waveform duty cycle is determined by comparing the PWM waveform with a preset waveform, and the switching transistor is turned on or off based on the waveform duty cycle.

6. The zero-crossing processing method based on the BOOST circuit according to claim 2, characterized in that, The negative zero-crossing interval includes intervals t1, t2, and t3. After determining that the current output current value is within the negative zero-crossing interval, the following steps are also included: Determine whether the current output current value is within the negative zero interval set; When the current output current value is in the t1 range, the switching transistors Q31 and Q34 are turned on, and the current flows through the switching transistors Q31 and Q34 to the energy storage inductor. When the current output current value is in the t2 range, the switch Q31 is turned on and the switch Q34 is turned off, and the current flows to the energy storage inductor through the body diode of the switch Q34. When the current output current value is in the t3 range, the switch Q31 is turned off and the switch Q37 is turned on. The current flows through the body diode of the switch Q40 and the MOSFET of the switch Q37 to the energy storage inductor.

7. The zero-crossing processing method based on the BOOST circuit according to claim 2, characterized in that, The positive zero-crossing interval includes intervals t4, t5, and t6. After determining that the current output current value is within the positive zero-crossing interval, the following steps are also included: Determine whether the current output current value is within the set of positive zero intervals; When the current output current value is in the t4 range, the MOSFET of switch Q34 is turned on, and the current flows from the energy storage inductor through the MOSFET of switch Q34 and the body diode of switch Q31 to the output terminal. When the current output current value is in the t5 range, the MOSFET of switch Q40 is turned on and the MOSFET of switch Q34 is turned off. The current flows from the energy storage inductor through the body diode of switch Q37 and the MOSFET of switch Q40 to the UN terminal. When the current output current value is in the t6 range, the MOSFETs of switching transistors Q40 and Q37 are turned on, and the current flows from the energy storage inductor through the MOSFETs of Q37 and Q40 to the UN terminal.

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