Alternating chopper control method and device for four-branch ac voltage regulating circuit

Abstract

This invention discloses an alternating chopping control method and apparatus for a four-branch AC voltage regulator circuit, relating to the field of power electronics control technology. The method is executed by a controller, which acquires the effective value of the fundamental AC voltage and generates a target duty cycle signal, focusing on the micro-timing allocation of alternating positive and negative half-cycle chopping. During the positive half-cycle, the first and second power switch branches on the input side are driven to perform complementary chopping, while the third and fourth power switch branches on the output side remain continuously conducting. During the negative half-cycle, the operation is reversed, and chopping is performed by the power switch branches on the output side. Furthermore, the controller suspends the PWM signal in the voltage zero-crossing range to prevent switch jitter and reconstructs the underlying switch state to form a low-loss sliding pass-through path when the voltage deviation is extremely small. This invention solves the problems of main inductor bias and uneven device stress through pure software timing mirror symmetry control, achieving safe and smooth switching of bidirectional voltage regulation in multiple modes.

Description

Technical Field

[0001] This invention relates to the field of power electronic conversion control technology, specifically to an alternating chopper control method and device for a four-branch AC voltage regulating circuit. Background Technology

[0002] In applications such as wide-range adjustable AC power supplies and voltage regulation in power distribution systems, AC voltage regulators play a crucial role. Existing AC voltage regulators mainly employ methods such as tap switching of power frequency transformers, thyristor phase-shift voltage regulation, and multi-stage AC-DC-AC conversion. However, power frequency transformers are large, heavy, inefficient, and have discrete voltage regulation taps; thyristor phase-shift voltage regulation can basically only reduce voltage, resulting in high harmonics and low power factor; while multi-stage AC-DC-AC conversion can achieve voltage boosting, voltage reduction, and better waveform quality, it is structurally complex, costly, and difficult to control.

[0003] To improve efficiency and harmonics to some extent, some AC chopper-type voltage regulation topologies use a few power switches to chop the inductor. However, most existing chopper control methods are designed for step-down operation and cannot simultaneously handle both step-up and step-down without relying on a power frequency transformer. More seriously, existing control logic often uses the same bridge arm or the same power branch for high-frequency chopping during the positive and negative half-cycles of AC. This asymmetry in the underlying drive timing leads to extremely uneven thermal stress distribution in the devices, easily causing severe DC bias in the main inductor and significantly shortening the equipment's lifespan. Furthermore, existing control algorithms rely heavily on macroscopic numerical calculations and mode determination, neglecting the fine-grained timing allocation of the underlying physical switching actions. This results in switching jitter near the zero-crossing point and an inability to achieve a smooth, zero-impact transition at the microscopic level during gliding and other states, making it difficult to adapt to modern power distribution networks with extremely high requirements for voltage quality and equipment reliability. Summary of the Invention

[0004] To address the technical problems in existing AC voltage regulation control methods, such as uneven thermal stress distribution of devices during positive and negative half-cycles, severe DC bias of the main inductor, and zero-crossing transition jitter caused by limitations in macroscopic logic, the present invention aims to provide an alternating chopper control method and device for a four-branch AC voltage regulation circuit. This invention achieves efficient and smooth bidirectional buck-boost and multi-mode collaborative operation without relying on complex hardware by alternating allocation of underlying micro-timing and reconfiguration of power switching device states.

[0005] To achieve the above objectives, a first aspect of the present invention provides an alternating chopper control method for a four-branch AC voltage regulator circuit, applied to a controller. The AC voltage regulator circuit includes a main inductor and a first power switch branch, a second power switch branch, a third power switch branch, and a fourth power switch branch arranged around the input and output sides of the main inductor. The control method comprises the following steps: Step S1: Obtain the fundamental effective value of the AC input voltage, the effective value of the AC output voltage, and the target output voltage, and detect the current half-cycle polarity of the AC input voltage; Step S2: Based on the deviation between the fundamental effective value and the target output voltage, generate a target duty cycle signal for controlling the high-frequency chopping width; Step S3: Based on the current half-cycle polarity, perform alternating timing control of the underlying PWM drive signal: When the AC input voltage is detected to be in the positive half-cycle, a high-frequency complementary PWM drive signal based on the target duty cycle signal is output to the first power switch branch and the second power switch branch. At the same time, a level control signal that keeps the circuit fully on is forcibly output to the third power switch branch and the fourth power switch branch. When the AC input voltage is detected to be in the negative half-cycle, a high-frequency complementary PWM drive signal based on the target duty cycle signal is output to the third power switch branch and the fourth power switch branch. At the same time, a level control signal that is forced to remain fully on is output to the first power switch branch and the second power switch branch.

[0006] A second aspect of the present invention provides an alternating chopper control device for a four-branch AC voltage regulator circuit, applied to a controller. The AC voltage regulator circuit includes a main inductor and first to fourth power switch branches arranged around the input and output sides of the main inductor. The control device includes a data acquisition module, a duty cycle calculation module, and an alternating chopper control module. The alternating chopper control module is used to perform alternating timing control of the underlying PWM drive signal based on the current half-cycle polarity, and its specific control logic is consistent with the control method described above. Compared with the prior art, the beneficial effects of the present invention are: A low-level control timing mechanism that alternately allocates chopping authority for positive and negative half-cycles is introduced. During the positive half-cycle, the input-side branch is chopped and the output side is continuously powered on. During the negative half-cycle, the operation is reversed. This mirror-symmetric wave generation logic allows the power device to enter a low-frequency rest after undergoing high-frequency hard switching for half a power frequency cycle. This not only ensures absolute equilibrium of the device's thermal stress but also achieves perfect reset of the main inductor flux, eliminating the risk of DC bias from the physical underlying drive logic.

[0007] Microscopic timing intervention is embedded at the underlying level. When voltage regulation is not required, the PWM signal is directly suspended and a specific branch is forced to remain on to form a single physical direct path, effectively reducing switching losses to zero. In the AC zero-crossing interval, which is prone to malfunction, a microscopic timing control strategy is adopted to briefly suspend the chopper, maintain the current direct path, and delay the reversal, completely eliminating the short-circuit risk caused by zero-crossing jitter.

[0008] By precisely controlling the micro-states of the main inductor's "energy absorption" and "energy release" within an extremely short PWM cycle, the abstract duty cycle control is transformed into a direct "transmission" or "superposition" action of the induced voltage of the main inductor. Without increasing hardware costs, seamless, wide-range bidirectional voltage regulation from AC to AC is achieved, greatly improving the operational reliability of the device in complex power distribution environments. Attached Figure Description

[0009] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0010] The accompanying drawings used in the description are briefly introduced.

[0011] Figure 1 This is a schematic diagram of the AC voltage regulation physical topology environment used in an embodiment of the present invention; Figure 2 This is a schematic diagram of the main flow of the alternating chopper control method provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the branch control state logic under each half-cycle mode of the underlying layer provided in an embodiment of the present invention; Figure 4 A schematic diagram of the virtual module structure of the alternating chopper control device provided in an embodiment of the present invention. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of this invention clearer, the following provides a more detailed description of an alternating chopper control method and apparatus for a four-branch AC voltage regulating circuit, in conjunction with specific control logic and runtime sequence. It should be understood that the specific embodiments described herein are merely illustrative of the control mechanism and signal interaction process of this invention and are not intended to limit the basic physical hardware topology of this invention.

[0013] like Figure 1-4 As shown, this embodiment of the invention provides an alternating chopper control method based on a four-branch AC voltage regulation physical topology. In the control logic of this embodiment, the AC high-voltage port corresponds to the grid input side, and the AC low-voltage port corresponds to the load output side. As the physical carrier and control object of this method, the four-branch AC voltage regulation circuit mainly includes: AC high-voltage and AC low-voltage ports are used for interaction with upstream power grids and downstream loads. The main inductor connected in series in the main power path; And four power switch branches symmetrically arranged around the input and output sides of the main inductor.

[0014] Specifically, the first and second power switch branches are located on the input side of the main inductor, while the third and fourth power switch branches are located on the output side of the main inductor.

[0015] In actual operation, the first to fourth power switching branches mentioned above all include fully controlled bidirectional power switching devices (such as anti-parallel wide bandgap semiconductor devices). The controller (or digital signal processor DSP) in this embodiment is electrically connected to the control terminals (such as gate drive circuits) of the first to fourth power switching branches, respectively. The core of this invention lies in how the controller, based on the power grid state, issues specific PWM (pulse width modulation) drive signals or long-on / long-off level control signals to these four branches on an extremely microscopic time scale, thereby reconstructing the energy path of the main inductor without relying on the power frequency transformer.

[0016] The method provided in this invention overcomes the technical bottleneck of thermal stress concentration caused by the shared chopper tube for the positive and negative half-cycles in traditional AC voltage regulation circuits. Its main process strictly follows the following timing logic: Step S1: Within each extremely short control cycle (e.g., the reciprocal of the switching frequency), the controller acquires the fundamental RMS value of the AC input voltage, the RMS value of the AC output voltage, and the target output voltage sent from an external source or host computer in real time via a low-level sampling interrupt. More importantly, the controller's internal digital phase-locked loop (PLL) or zero-crossing detection algorithm captures the instantaneous phase of the AC input voltage in real time, thereby accurately detecting and marking the current half-cycle polarity (positive or negative half-cycle). This polarity flag is an absolute prerequisite for triggering the subsequent "alternating allocation" logic.

[0017] Step S2: Based on the deviation between the fundamental RMS value and the target output voltage, the controller generates a "target duty cycle signal" in its internal logic unit to control the high-frequency chopping width. During this process, the controller compensates for and smooths the error signal, and strictly applies amplitude limiting (constraining its physical meaning within the duty cycle range of 0 to 1) and rate-of-change limiting (limiting the rise or fall slope of the duty cycle signal between adjacent switching cycles). This processing ensures that the final output target duty cycle signal not only reflects the system's energy throughput requirements but also prevents huge inductor current surges caused by sudden instruction changes at the underlying code level.

[0018] Step S3: In this step, the controller divides the underlying PWM wave generation module into two completely mirror-symmetrical workflows based on the polarity flag determined in S1, specifically: Positive half-cycle timing logic: When the controller detects that the AC input voltage is in the positive half-cycle range, the internal wave sequencer immediately activates. At this time, the controller "directively assigns" the high-frequency chopping task to the first and second power switch branches located on the main inductor input side. Specifically, the controller outputs high-frequency complementary PWM drive signals to the first and second power switch branches according to the target duty cycle signal generated by S2 (i.e., both alternately turn on and off within the same PWM cycle, and simultaneously turn off during the software dead time to prevent short circuits).

[0019] Simultaneously (with absolutely synchronous execution of the instruction), the controller forcibly sends a fixed high-level control signal to the third and fourth power switch branches located on the output side, stating "keep fully on". Under the action of this instruction, the power switching devices in the third and fourth power switch branches are kept in the on state and no longer perform high-frequency switching, merely serving as a physical bridge for low-frequency energy flow.

[0020] Negative half-cycle sequential logic: When the AC input voltage crosses zero and enters the negative half-cycle, the timing distributor inside the controller instantly undergoes a "role reversal". At this time, the controller cancels the high-frequency chopping privileges of the first and second power switch branches, and instead outputs high-frequency complementary PWM drive signals based on the target duty cycle signal to the third and fourth power switch branches.

[0021] Simultaneously, the controller forcibly sends a "keep fully on" level control signal to the first and second power switch branches. Throughout the entire duration of the negative half-cycle, the first and second power switch branches on the input side are kept in a continuously conducting state, and the chopping task is entirely undertaken by the power switch branches on the output side.

[0022] As can be seen from the above, through the above control method, the controller forcibly separates the chopping execution body of the positive half-cycle and the negative half-cycle at the code level. Through the underlying micro-timing control of half-cycle rotation and alternating chopping, all power switching devices can enter the low-frequency conduction cooling stage in the next half-cycle after experiencing the high-frequency hard switching loss of half a power frequency cycle.

[0023] This fundamentally eliminates the risk of thermal breakdown failure caused by continuous high-frequency chopping in a single branch, achieving absolute symmetry in the thermal stress of the entire machine. Simultaneously, because the chopping excitation source is applied alternately across the main inductor, the magnetic flux establishment and reset process within the main inductor forms a perfect mirror symmetry in both the positive and negative half-cycles, physically eliminating the generation of DC bias.

[0024] Within the aforementioned alternating chopping timing framework, the main inductor undergoes high-frequency energy absorption and release microphysical processes within an extremely short PWM cycle (e.g., 50 microseconds). The controller reconstructs the energy transfer mechanism by changing the time ratio of energy absorption and release (duty cycle) and combining it with the system's buck-boost judgment flags.

[0025] Furthermore, the energy absorption and release states during the chopping cycle (taking the positive half-cycle as an example): During any PWM cycle in the positive half-cycle: During the energy absorption state: The controller drives the first power switch branch to conduct and forces the second power switch branch to turn off. At this time, the main grid input terminal, the first power switch branch, and the main inductor form a closed loop, and the main inductor is only connected to the input side loop. Since the inductor is subjected to a positive input voltage, the inductor current rises linearly, and the input side electrical energy is converted into magnetic field energy and stored inside the main inductor.

[0026] During the energy discharge phase: The controller drives the first power switch branch to turn off and, after the dead time, drives the second power switch branch to turn on. At this time, the input side of the main inductor is cut off, and the magnetic field energy it has stored must find a discharge path. Under the controller's command, the current flows to the output side through the second power switch branch, the main inductor, and through the third and fourth power switch branches, which are kept in a continuously conducting state, completing a high-frequency energy pumping operation.

[0027] During any PWM cycle in the negative half-cycle, the main inductor also undergoes a tightly controlled energy throughput process, but the chopping execution entity is physically transferred, as follows: During the energy absorption state: The controller drives the third power switch branch to conduct and forces the fourth power switch branch to turn off. At this time, the main inductor is connected to the underlying electrical circuit through the third power switch branch. Since the AC input voltage is in the negative half-cycle polarity at this time, the terminal voltage of the main inductor is reversed, and the current rises linearly in the negative polarity. The electrical energy is converted into magnetic field energy and stored inside the main inductor, completing the independent energy absorption action in the negative half-cycle.

[0028] During the energy release phase: The controller drives the third power switch branch to turn off, and after a very short hardware dead time, drives the fourth power switch branch to turn on. At this time, the energy absorption circuit of the main inductor is cut off, and the magnetic field energy stored inside must be released. Under the low-level command of the controller, the current flows through the currently conducting fourth power switch branch, the main inductor, and through the first and second power switch branches, which are forced to remain continuously conducting during the negative half-cycle, smoothly pushing the energy to the output side, thus completing one high-frequency energy transfer during the negative half-cycle. This completely independent mirror energy absorption and release mechanism for the positive and negative half-cycles ensures, from a physical level, the perfect reset of the inductor flux throughout the entire power frequency cycle.

[0029] Differences in the physical mechanisms of buck and boost commands: The controller not only calculates the duty cycle, but also determines whether it is in buck or boost mode based on the relationship between the target output voltage and the fundamental RMS value. This directly determines the physical behavior in the energy release state. When the target duty cycle signal indicates buck mode: In the energy dissipation state, the main inductor is connected in series with both the input and output sides via the power switch branch that is in the on state. At this time, the controller is essentially "cutting off" part of the input energy. The main inductor acts like a high-frequency controlled valve, directly transferring the energy accumulated during the energy absorption phase, as well as some of the direct-through energy, to the output side according to the duty cycle ratio. Since the transfer time is less than the entire cycle, the average voltage (macroscopic manifestation) on the output side is naturally lower than the input voltage.

[0030] When the target duty cycle signal indicates boost mode, a qualitative change occurs in the physical mechanism. In the energy release state, the rate of change of current (di / dt) of the main inductor generates an extremely high induced electromotive force across its terminals. Driven by the controller's specific duty cycle, the main inductor is no longer merely a channel for energy transfer, but rather an equivalent voltage source. The induced voltage it generates is superimposed in series with the current AC input voltage in the physical circuit, and the combined voltage is pushed to the output. Therefore, even if the peak value of the input AC waveform is only 220V, with the superposition compensation of the induced voltage, the output can smoothly obtain a voltage peak value of over 260V, perfectly achieving seamless AC-to-AC boost regulation.

[0031] It also includes low-level timing control under special operating conditions: To ensure absolute system stability under all operating conditions, the controller of this invention also incorporates two special timing control strategies—glide pass-through and zero-crossing anti-shake—deeply at the software level. Specifically: Coasting through control (zero high-frequency loss state): When the power grid quality is good, continuous high-frequency chopping will bring additional switching losses. To address this, a "voltage regulation dead zone" is set inside the controller. When the controller finds in step S1 that the deviation between the fundamental effective value and the target output voltage is extremely small and has fallen within the dead zone range, the controller's internal mode state machine will immediately jump and generate a "pass-through command".

[0032] Microscopic response: In response to the pass-through command, the controller's underlying PWM generator is instantly suspended, completely ceasing to output high-frequency complementary PWM drive signals to any branch. Immediately afterwards, the controller rewrites the GPIO port states, outputting a continuous high level (keeping it on) to the first and third power switch branches, and a continuous low level (keeping it off) to the second and fourth power switch branches.

[0033] Under this command, the four high-frequency branches instantly degenerate into two static conductors. The main inductor is directly connected in series between the AC input and output terminals, no longer bearing any high-frequency voltage excitation. The system forms a single direct physical path for energy transmission, with the main inductor used only as a low-frequency filter choke. This control method effectively reduces the system's switching losses to zero at the software level, while ensuring zero-delay energy transfer.

[0034] Zero-crossing transition timing control (anti-bouncing and anti-shoo-through short-circuit): During the extremely short instant when the AC voltage crosses zero (from positive to negative or vice versa), due to sampling noise, grid harmonics, and the parasitic capacitance of the power switching devices, polarity misjudgment is very likely to occur. This causes the controller to send high-frequency pulses to the upper and lower power switching devices on the same bridge arm at the same time, which in turn leads to a serious hardware short circuit.

[0035] The method of this invention solves this problem through micro-time intervention: when the controller detects the phase, it pre-sets an extremely narrow "zero-crossing interval" (e.g., a window between -5V and +5V for the fundamental instantaneous value).

[0036] Microscopic response: When the controller detects that the input voltage has fallen into the zero-crossing range, it triggers a zero-crossing interrupt. The controller forcibly "freezes" the current high-frequency chopping action (suspends the PWM output) and relies on a software latch to keep the pair of power switches that were on in the previous microsecond on continuing to conduct, while the other pair remains off. At this time, the main inductor is in a static series path without high-frequency chopping.

[0037] The controller continuously polls the sampled values ​​silently in the background until it confirms that the instantaneous value of the input voltage has indeed crossed the other boundary of the zero-crossing interval (e.g., reaching +5V or -5V or higher). Only after confirming that the polarity reversal is finalized and there is no jitter, does it release the PWM suspension state and reallocate the alternating chopping task according to the new half-cycle polarity (transferring to the other half-cycle logic in S3). This underlying timing "maintain suspension state" strategy completely eliminates erroneous switching near the zero-crossing point, ensuring the absolute safety of the hardware topology during power frequency cycle switching.

[0038] Corresponding to the control method described above, this invention also provides an alternating chopper control device for a four-branch AC voltage regulating circuit. This device is not a physical circuit board, but rather a collective term for a series of virtual logic function modules residing within a digital controller (such as a DSP or MCU).

[0039] Data acquisition module: Responsible for driving the underlying ADC (Analog-to-Digital Converter) peripherals to perform high-speed oversampling of AC input / output voltages. It integrates digital filtering algorithms and phase-locked loop (PLL) routines, which can extract the fundamental effective value from physical signals containing harmonics and accurately output the current half-cycle polarity flag and zero-crossing interval flag, providing a data base for subsequent logic.

[0040] Duty cycle calculation module: This module receives the deviation data transmitted by the data acquisition module. Internally, it does not rely on a conventional single linear amplification, but instead incorporates a dual amplitude / slope limiting unit. The target duty cycle signal calculated by this module is a smoothed digital variable strictly limited within safe physical boundaries, directly representing the proportion of time the main inductor needs to "absorb energy" in the current cycle.

[0041] The alternating chopper control module is responsible for converting the abstract duty cycle variable into a hardware-recognizable drive signal. Internally, this module contains a dynamically routeable PWM generator array. It monitors the half-cycle polarity flag in real time: when the flag is positive, it routes the PWM generator to the first and second power switch branches and locks the third and fourth power switch branches high; when the flag flips to negative, it instantly switches the internal routing matrix, switching the PWM channel to the third and fourth power switch branches while simultaneously locking the input side. Furthermore, this module integrates "pass-through overriding logic" and "zero-crossing suspension logic." Once a corresponding instruction is received, it has the highest priority, directly overriding and shutting down the underlying PWM timer, taking over the port state, and thus executing micro-control actions such as coasting pass-through or zero-crossing debouncing.

[0042] In summary, the alternating chopper control method and apparatus provided by this invention, through the precise allocation of the controller's underlying timing, endows the four-branch AC voltage regulation circuit with unprecedented multi-mode smooth switching capabilities. It completely eliminates the reliance on complex hardware wiring, achieving groundbreaking technical effects in areas such as microscopic energy flow, zero-crossing anti-jitter, lossless gliding, and device thermal stress equalization solely through pure software timing reconstruction, thus possessing extremely high industrial application value.

[0043] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An alternating chopper control method for a four-branch AC voltage regulating circuit, applied to a controller, wherein the AC voltage regulating circuit includes a main inductor and a first power switch branch, a second power switch branch, a third power switch branch, and a fourth power switch branch arranged around the input and output sides of the main inductor; characterized in that, The control method includes the following steps: Step S1: Obtain the fundamental effective value of the AC input voltage, the effective value of the AC output voltage, and the target output voltage, and detect the current half-cycle polarity of the AC input voltage; Step S2: Based on the deviation between the fundamental effective value and the target output voltage, calculate the target duty cycle signal, and adjust the pulse width of the high-frequency chopper output to the power switch branch according to the target duty cycle signal; Step S3: Based on the current half-cycle polarity, perform alternating timing control of the underlying PWM drive signal: When the AC input voltage is detected to be in the positive half-cycle, a high-frequency complementary PWM drive signal based on the target duty cycle signal is output to the first power switch branch and the second power switch branch. At the same time, a level control signal that keeps the circuit fully on is forcibly output to the third power switch branch and the fourth power switch branch. When the AC input voltage is detected to be in the negative half-cycle, a high-frequency complementary PWM drive signal based on the target duty cycle signal is output to the third power switch branch and the fourth power switch branch. At the same time, a level control signal that is forced to remain fully on is output to the first power switch branch and the second power switch branch.

2. The control method according to claim 1, characterized in that, In step S3, during the positive half-cycle of the chopping cycle, the microscopic energy flow state of the main inductor is determined by the following control logic: During the energy absorption state of the main inductor, the first power switch branch is turned on and the second power switch branch is turned off, so that the main inductor is connected only to the input side circuit to absorb energy. During the energy release state of the main inductor, the first power switch branch is turned off and the second power switch branch is turned on, so that the main inductor releases energy. At this time, the third power switch branch and the fourth power switch branch serve as energy paths to transmit the induced voltage to the output side.

3. The control method according to claim 1, characterized in that, In step S3, during the negative half-cycle of the chopping cycle, the microscopic energy flow state of the main inductor is determined by the following control logic: During the energy absorption state of the main inductor, the third power switch branch is turned on and the fourth power switch branch is turned off, so that the main inductor is connected only to the output side circuit to absorb energy. During the energy release state of the main inductor, the third power switch branch is turned off and the fourth power switch branch is turned on, so that the main inductor releases energy. At this time, the first power switch branch and the second power switch branch, which are in a fully on state, serve as energy paths to transmit the induced voltage to the output side.

4. The control method according to claim 1, characterized in that, It also includes the taxiing through control steps: When the deviation between the fundamental effective value and the target output voltage falls within the preset voltage regulation dead zone, a pass-through command is generated; In response to the pass-through command, the output of the high-frequency complementary PWM drive signal is stopped, and the first power switch branch and the third power switch branch are controlled to remain continuously on, while the second power switch branch and the fourth power switch branch are controlled to remain off, so that the main inductor is connected in series between the input and output terminals, forming a single energy pass-through physical path without applying a high-frequency chopping voltage.

5. The control method according to claim 1, characterized in that, It also includes zero-crossing transition timing control steps: When the instantaneous phase or fundamental instantaneous value of the AC input voltage is detected to be within a preset zero-crossing interval, the controller briefly suspends and stops outputting the high-frequency complementary PWM drive signal. Only one pair of power switch branches that are in the conducting state during the current half-cycle remains conducting, while the other pair of power switch branches remains closed. This keeps the main inductor in a series path without applied chopping voltage to maintain a shoot-through state until the AC input voltage is detected to have crossed the zero-crossing interval. Then, the alternating chopping task of the underlying PWM drive signal is allocated according to the polarity of the next half-cycle to avoid switching malfunctions caused by zero-crossing jitter.

6. The control method according to claim 2 or 3, characterized in that, The target duty cycle signal indicates whether the current mode is buck or boost, during the discharge state of the main inductor: When the target duty cycle signal indicates buck mode, the main inductor is connected in series with the input and output sides through the power switch branch in the on state, and directly transfers the energy of the absorbed input voltage to the output side. When the target duty cycle signal indicates boost mode, the main inductor is connected in series with the input and output sides through the power switch branch in the on state, and the induced voltage generated by it is superimposed on the AC input voltage and pushed to the output terminal together, thereby realizing AC boost regulation where the peak value of the output voltage is higher than the peak value of the AC input voltage.

7. An alternating chopper control device for a four-branch AC voltage regulating circuit, used to execute the control method as described in any one of claims 1 to 6, applied to a controller, wherein the AC voltage regulating circuit includes a main inductor and a first power switch branch, a second power switch branch, a third power switch branch, and a fourth power switch branch arranged around the input and output sides of the main inductor, characterized in that, The control device includes: The data acquisition module is used to acquire the fundamental effective value of the AC input voltage, the effective value of the AC output voltage, and the target output voltage, and to detect the current half-cycle polarity of the AC input voltage. The duty cycle calculation module is used to generate a target duty cycle signal for controlling the high-frequency chopping width based on the deviation between the fundamental effective value and the target output voltage. The alternating chopper control module is used to perform alternating distribution timing control of the underlying PWM drive signal based on the current half-cycle polarity: When the AC input voltage is detected to be in the positive half-cycle, a high-frequency complementary PWM drive signal based on the target duty cycle signal is output to the first power switch branch and the second power switch branch, and at the same time, a level control signal that keeps fully on is forcibly output to the third power switch branch and the fourth power switch branch. When the AC input voltage is detected to be in the negative half-cycle, a high-frequency complementary PWM drive signal based on the target duty cycle signal is output to the third power switch branch and the fourth power switch branch, and at the same time, a level control signal that keeps fully on is forcibly output to the first power switch branch and the second power switch branch.

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