Full-effect synchronous rectification system and control method

Abstract

The invention relates to the technical field of power supply modulation, in particular to a full-effect synchronous rectification system and a control method, and the system comprises a control module and a power supply modulation module. The power supply modulation module forms a complete power conversion loop from direct current input to a load, and the synchronous rectification unit is provided with a synchronous rectification switch tube. The key innovation of the control module is that the control module generates and outputs two paths of control signals with mutually independent logic, namely an inversion PWM signal and a synchronous rectification control signal. On the basis, the control module is intelligently configured to actively control the synchronous rectification switch tube to be kept on in a follow current stage generated by switching of the inverter switch. Therefore, the follow current can continuously flow through a low-resistance conducting channel of the switching tube instead of a high-loss diode in the low-resistance conducting channel, so that the rectification loss is greatly reduced in the whole working period. In addition, the control method is applied to the system of the scheme, and therefore the control method has all the advantages of the scheme.

Description

Technical Field

[0001] This invention relates to the field of power modulation technology, specifically to a fully effective synchronous rectification system and control method. Background Technology

[0002] In the design of switching power supplies, especially high-power DC-DC converters, the efficiency of the rectification stage has a significant impact on the overall performance. Early power supply designs commonly used diodes for rectification (see...). Figure 4 The inherent forward voltage drop (approximately 0.5V-0.7V) of the rectifier diode when it is turned on will result in significant conduction losses when the current is large. Taking a 1000A output current as an example, the losses of the rectifier diode alone can reach over 500W.

[0003] To reduce this loss, synchronous rectification technology is widely used. This technology uses MOSFETs with very low on-resistance instead of rectifier diodes, and their on-state voltage drop is proportional to the product of current and on-resistance. For example, using multiple MOSFETs in parallel can reduce the equivalent on-resistance to the order of 0.0001Ω, and the on-state voltage drop at a current of 1000A is only about 0.1V, corresponding to a loss of about 100W, which is significantly lower than that of diode rectification.

[0004] Existing synchronous rectification technology typically employs follower control, meaning the drive signal of the synchronous rectifier MOSFET is synchronized with the PWM signal of the primary-side inverter bridge. This method leverages the low on-resistance of MOSFETs during the energy transfer phase from the inverter bridge to the secondary side, but suffers from a significant efficiency bottleneck during the inductor freewheeling phase. Specifically, when all inverter bridge switches are off, the output inductor needs to maintain the load current through the freewheeling path. Under follower control, the corresponding synchronous rectifier is also off during this phase, forcing the freewheeling current to flow through the body diode inside the MOSFET. The forward voltage drop of this body diode is similar to that of a traditional diode, typically around 0.6V.

[0005] Of particular concern is that under low output voltage and high current conditions, the inverter PWM duty cycle decreases significantly, resulting in a substantial increase in the proportion of the freewheeling phase within the entire switching cycle. In this situation, a freewheeling current equivalent to the load current flows through the body diode of the high-voltage dropout diode for an extended period, leading to a sharp increase in additional conduction losses. For example, at a freewheeling current of 1000A, the losses caused by the body diode alone can rise to approximately 600W, severely weakening the efficiency gain brought by synchronous rectification during the power transfer phase and making it difficult to improve overall efficiency in low-voltage, high-current scenarios.

[0006] Therefore, the existing synchronous rectification schemes for high-power DC-DC converters still have significant room for improvement in terms of losses during the freewheeling stage. A rectification control scheme that can more effectively control the current path and further reduce conduction losses is needed in this stage. Summary of the Invention

[0007] The primary objective of this invention is to address the problem of significant losses in the freewheeling stage of existing synchronous rectification schemes for high-power DC-DC converters due to the conduction of the body diode, and to provide a fully efficient synchronous rectification system.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A fully efficient synchronous rectification system includes a control module and a power modulation module. The power modulation module includes a DC input terminal, an inverter unit, a transformer unit, a synchronous rectification unit, and a load terminal. The synchronous rectification unit is equipped with a synchronous rectification switch. The primary windings of the DC input terminal, the inverter unit, and the transformer unit are connected in series. The secondary winding of the transformer unit, the synchronous rectification unit, and the load terminal are connected in series to form a rectified output circuit. The control module is connected to the control terminals of the inverter unit and the synchronous rectification unit to output an inverter pulse width modulation signal to the inverter unit and a synchronous rectification control signal to the synchronous rectification unit. The logic of the synchronous rectification control signal is independent of the logic of the inverter pulse width modulation signal. Furthermore, the control module is configured to: during the freewheeling phase, control the synchronous rectification switch in the synchronous rectification unit to be in the on state so that the freewheeling current flows through the conductive channel of the synchronous rectification switch.

[0009] This invention utilizes a control module (e.g., a digital signal processor) to pre-calculate and generate a synchronous rectification control signal that is logically completely independent of the primary-side inverter pulse width modulation signal, based on the system's input and preset output parameters. This control method does not rely on real-time detection and tracking of the primary-side switching state, thus eliminating the lag in signal generation. Furthermore, the control module is intelligently configured to keep the synchronous rectification switch in the synchronous rectification unit on during the freewheeling phase formed by the switching state of the inverter unit. This provides a path for the freewheeling current through its low-resistance conductive channel, avoiding or significantly reducing current flow through the high-loss body diode. By providing a continuous channel path, the efficiency can be improved by approximately 20% compared to existing synchronous rectification technologies. Even with high output current and high output voltage, although the freewheeling phase is relatively short, this solution can still eliminate the inherent losses during this period, achieving an efficiency improvement of approximately 2%. For example, under the condition of the same output current of 1000A, this invention can achieve a high efficiency performance similar to that of traditional solutions at 12V output voltage, even when the output voltage is as low as 2V or even 1V. Compared with the prior art, this invention breaks through the limitations of the traditional follower control mode, realizing efficient and precise independent control of the rectifier circuit throughout the entire working cycle (including the freewheeling phase), and significantly improving the overall efficiency and dynamic performance of the converter under harsh conditions such as low output voltage and high current.

[0010] Furthermore, the control module includes a digital signal processor (DSP); the DSP is configured with an inverter control signal output terminal and a synchronous rectification control signal output terminal; the inverter control signal output terminal is connected to the control terminal of the inverter unit; the synchronous rectification control signal output terminal is connected to the control terminal of the synchronous rectification unit. In this solution, the DSP has independent inverter control signal output terminals and synchronous rectification control signal output terminals, which are directly connected to the control terminals of the inverter unit and the synchronous rectification unit, respectively. This hardware architecture provides the physical basis for realizing the aforementioned logically independent dual-channel signal output.

[0011] Furthermore, the synchronous rectification unit includes two synchronous rectification circuits. The control module calculates and generates the inverter pulse width modulation signal and the corresponding synchronous rectification control signal based on the input power parameters and preset power output parameters. Additionally, according to the switching logic of the inverter pulse width modulation signal, the control module generates a synchronous rectification control signal during the freewheeling phase to control the simultaneous conduction of the synchronous rectification switches of the two synchronous rectification circuits. This solution's synchronous rectification unit includes two synchronous rectification circuits. The control module intelligently controls the simultaneous conduction of the two rectifier diodes during the freewheeling phase based on the inverter signal switching logic, and generates corresponding drive signals. This control mechanism provides a parallel low-impedance path for the current during the freewheeling phase, thereby more effectively reducing freewheeling losses and improving the system's adaptability and overall efficiency under a wide range of operating conditions.

[0012] Furthermore, the control module calculates and determines the start and end times of the freewheeling phase based on the duty cycle of the inverter pulse width modulation signal and a preset dead time. In this scheme, the control module can accurately calculate the start and duration of the freewheeling phase through internal calculations based on the current duty cycle of the inverter pulse width modulation signal and the preset dead time parameter. This eliminates the need for external detection circuitry to predict the freewheeling window, providing a precise time reference for core control decisions.

[0013] Furthermore, the inverter unit includes a first inverter circuit and a second inverter circuit that are alternately turned on, and the synchronous rectification unit includes a corresponding first synchronous rectification circuit and a second synchronous rectification circuit; within one working cycle, let the on-time of the first inverter circuit be T1, the on-time of the second inverter circuit be T3, the first freewheeling phase time from the turn-off of the first inverter circuit to the turn-on of the second inverter circuit be T2, and the second freewheeling phase time from the turn-off of the second inverter circuit to the turn-on of the first inverter circuit be T4; the control module is configured to: control the on-time of the synchronous rectification switch in the first synchronous rectification circuit to be T1+T2+T4, and control the on-time of the synchronous rectification switch in the second synchronous rectification circuit to be T3+T2+T4. In this scheme, the control module configures the conduction time of the first synchronous rectifier switch to T1+T2+T4 and the conduction time of the second synchronous rectifier switch to T3+T2+T4, ensuring that both synchronous rectifier switches are in a controlled conduction state during the freewheeling phase (T2 and T4) when both inverter circuits are off. In this state, the freewheeling current no longer depends on the high-loss body diode inside either switch, but instead forms a closed loop through the parallel low-impedance channel formed by the two conducting switches. Specifically, during T2 and T4, the freewheeling current in the inductor can simultaneously flow through the conductive channels of the first and second synchronous rectifier switches, forming a parallel path, thereby minimizing the voltage drop during freewheeling and avoiding the inherent losses caused by the body diode conduction. This control strategy physically ensures that the current flows only through the low-impedance channel, achieving efficient energy cycling during the freewheeling phase.

[0014] Furthermore, the synchronous rectifier switch is a metal-oxide-semiconductor field-effect transistor.

[0015] Furthermore, the control module is configured to adaptively adjust the timing of the synchronous rectification control signal used to control the conduction of the freewheeling phase according to the duty cycle of the inverter pulse width modulation signal, wherein the duty cycle is inversely proportional to the conduction time of the synchronous rectification switch in the freewheeling phase. In this scheme, when the duty cycle decreases, the control module will automatically extend the conduction time of the synchronous rectification switch in the freewheeling phase; conversely, when the duty cycle increases, the conduction time will be shortened accordingly. Through this adaptive adjustment that is inversely proportional to the duty cycle, the system can automatically optimize the conduction strategy of the freewheeling phase over a wider voltage range to cope with different operating conditions, thereby maintaining and improving overall efficiency.

[0016] Another objective of this invention is to provide a fully effective synchronous rectification control method, applicable to a fully effective synchronous rectification system, comprising the following steps: receiving a power modulation command, acquiring input power parameters and preset power output parameters; calculating and generating logically independent inverter pulse width modulation signals and synchronous rectification control signals based on the input power parameters and preset power output parameters; sending the inverter pulse width modulation signals to an inverter unit to control the switching state of the inverter unit; sending the synchronous rectification control signals to a synchronous rectification unit to control the switching state of the synchronous rectification unit; wherein the switching state of the inverter unit forms a freewheeling phase; and, according to the synchronous rectification control signals, controlling the synchronous rectification switch in the synchronous rectification unit to conduct during the freewheeling phase, so that the freewheeling current flows through the conductive channel of the synchronous rectification switch. Compared with the prior art, the control method of this invention can be applied to the system described above, and therefore possesses all the advantages of the aforementioned solutions. Attached Figure Description

[0018] Figure 1 This is the principle of the invention. Figure 1 ; Figure 2 This is a flowchart of the present invention; Figure 3 This is the circuit diagram of the present invention; Figure 4 It is a schematic diagram of existing technology.

[0019] Label Explanation: Digital signal processor U1, inverter drive unit U2, rectifier drive unit U3, DC input terminal VBUS+, load terminal F1, transformer T0, first tap T1, center tap T3, second tap T2, first synchronous rectifier switch Q1, second synchronous rectifier switch Q2, first inverter switch Q3, second inverter switch Q4, third inverter switch Q5, fourth inverter switch Q6, inductor L1, capacitor C1. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings: Example 1: See Figure 1-3As shown, this embodiment discloses a full-efficiency synchronous rectification system, including a control module and a power modulation module. The power modulation module includes a DC input terminal, an inverter unit, a transformer unit, a synchronous rectification unit, and a load terminal. The synchronous rectification unit is equipped with a synchronous rectification switch. The primary windings of the DC input terminal, the inverter unit, and the transformer unit are connected in series in sequence. The secondary winding of the transformer unit, the synchronous rectification unit, and the load terminal are connected in series in sequence to form a rectification output circuit. The control module is connected to the control terminals of the inverter unit and the synchronous rectification unit respectively to output an inverter pulse width modulation signal to the inverter unit and a synchronous rectification control signal to the synchronous rectification unit. The logic of the synchronous rectification control signal is independent of the logic of the inverter pulse width modulation signal. Furthermore, the control module is configured to: during the freewheeling phase, control the synchronous rectification switch in the synchronous rectification unit to be in the on state so that the freewheeling current flows through the conductive channel of the synchronous rectification switch.

[0022] The aforementioned control module includes a digital signal processor (DSP). The DSP is equipped with an inverter control signal output terminal and a synchronous rectification control signal output terminal. The inverter control signal output terminal is connected to the control terminal of the inverter unit; the synchronous rectification control signal output terminal is connected to the control terminal of the synchronous rectification unit. The control module of this solution is composed of a DSP. This DSP has independent inverter control signal output terminals and synchronous rectification control signal output terminals, which are directly connected to the control terminals of the inverter unit and the synchronous rectification unit, respectively. This hardware architecture provides the physical basis for realizing the aforementioned logically independent dual-channel signal output.

[0023] The aforementioned synchronous rectification unit includes two synchronous rectification circuits. The control module calculates and generates an inverter pulse width modulation (PWM) signal and a corresponding synchronous rectification control signal based on the input power parameters and preset power output parameters. Furthermore, according to the switching logic of the inverter PWM signal, the control module generates a synchronous rectification control signal to simultaneously turn on the synchronous rectification switches of the two synchronous rectification circuits during the freewheeling phase. This solution's synchronous rectification unit includes two synchronous rectification circuits. Based on the switching logic of the inverter signal, the control module intelligently controls the simultaneous conduction of both rectifier diodes during the freewheeling phase and generates corresponding drive signals. This control mechanism provides a parallel low-impedance path for the current during the freewheeling phase, thereby more effectively reducing freewheeling losses and improving the system's adaptability and overall efficiency under a wide range of operating conditions.

[0024] The aforementioned control module calculates and determines the start and end times of the freewheeling phase based on the duty cycle of the inverter pulse width modulation signal and the preset dead time. In this scheme, the control module can accurately calculate the start and duration of the freewheeling phase through internal calculations based on the current duty cycle of the inverter pulse width modulation signal and the preset dead time parameter. Therefore, it can predict the freewheeling window without relying on external detection circuits, providing a precise time reference for core control decisions.

[0025] The aforementioned inverter unit includes a first inverter circuit and a second inverter circuit that alternately conduct, and the synchronous rectification unit includes a corresponding first synchronous rectification circuit and a second synchronous rectification circuit. Within one operating cycle, the conduction time of the first inverter circuit is T1, the conduction time of the second inverter circuit is T3, the first freewheeling phase time from the first inverter circuit being turned off to the second inverter circuit being turned on is T2, and the second freewheeling phase time from the second inverter circuit being turned off to the first inverter circuit being turned on again is T4. The control module is configured to control the conduction time of the synchronous rectifier switch in the first synchronous rectification circuit to be T1+T2+T4, and control the conduction time of the synchronous rectifier switch in the second synchronous rectification circuit to be T3+T2+T4. Under this control strategy, the two synchronous rectifier switches are in the conducting state during all freewheeling phases (T2 and T4) throughout the entire operating cycle, thus forming a parallel low-impedance freewheeling path. Specifically, during stages T2 and T4, the freewheeling current can flow through the conductive channels of the two synchronous rectifier switching transistors simultaneously, forming a parallel loop, thereby effectively avoiding the losses caused by the current flowing through the high voltage drop diode inside the switching transistor.

[0026] The aforementioned synchronous rectifier switch is a metal-oxide-semiconductor field-effect transistor.

[0027] The aforementioned control module is configured to adaptively adjust the timing of the synchronous rectification control signal used to control the conduction of the freewheeling phase based on the duty cycle of the inverter pulse width modulation signal, with the duty cycle inversely proportional to the conduction time of the synchronous rectifier switch during the freewheeling phase. In this scheme, when the duty cycle decreases, the control module automatically extends the conduction time of the synchronous rectifier switch during the freewheeling phase; conversely, when the duty cycle increases, the conduction time is shortened accordingly. Through this adaptive adjustment inversely proportional to the duty cycle, the system can automatically optimize the conduction strategy of the freewheeling phase over a wider voltage range to cope with different operating conditions, thereby maintaining and improving overall efficiency.

[0028] The following is in conjunction with the appendix Figure 3 The specific solution of this embodiment is explained as follows: The aforementioned control module includes a digital signal processor U1, an inverter drive unit U2, and a rectifier drive unit U3. The power modulation module includes a DC input terminal VBUS+, an inverter unit, a transformer unit, a synchronous rectifier unit, and a load terminal F1. The current input terminal of the inverter unit is electrically connected to the DC input terminal VBUS+, and its output terminal is connected to the input terminal of the transformer unit. The current input terminal of the synchronous rectifier unit is electrically connected to the output terminal of the transformer unit, and its current output terminal is electrically connected to the load terminal F1. The digital signal processor U1 is connected to the control terminal of the inverter unit through the inverter drive unit U2, and to the control terminal of the synchronous rectifier unit through the rectifier drive unit U3, thereby achieving physical separation and independent control of the control paths for the inverter and synchronous rectifier units.

[0029] The inverter unit includes a full-bridge circuit composed of a first inverter switch Q3, a second inverter switch Q4, a third inverter switch Q5, and a fourth inverter switch Q6. The transformer unit includes a transformer T0, whose primary winding is connected between the midpoints of the two arms of the inverter bridge. The secondary winding of transformer T0 has a first tap T1, a center tap T3, and a second tap T2. The synchronous rectification unit includes a first synchronous rectifier switch Q1 and a second synchronous rectifier switch Q2, forming the first and second synchronous rectifier circuits, respectively. The synchronous rectification unit also includes a filter unit composed of an inductor L1 and a capacitor C1. The digital signal processor U1 connects to and controls the gates of the first synchronous rectifier switch Q1 and the second synchronous rectifier switch Q2 through two independent drive circuits within the rectifier drive unit U3.

[0030] During power modulation, the DC input is converted into AC power by the inverter unit: the first inverter circuit composed of Q3 and Q6 and the second inverter circuit composed of Q4 and Q5 are alternately turned on, generating an alternating voltage on the primary side of transformer T0; after coupling, the secondary side AC power is rectified by the synchronous rectification unit. Specifically, when the first inverter circuit is turned on, the potential of the first tap T1 is positive, and the first synchronous rectifier switch Q1 is controlled to conduct, completing the positive half-cycle rectification; when the second inverter circuit is turned on, the potential of the second tap T2 is positive, and the second synchronous rectifier switch Q2 is controlled to conduct, completing the negative half-cycle rectification. During the critical freewheeling phase (i.e., when both inverter circuits are off), the digital signal processor U1 controls both the first synchronous rectifier switch Q1 and the second synchronous rectifier switch Q2 to remain on via an independent synchronous rectifier control signal. This allows the freewheeling current to flow through the low-resistance conductive channel of the switch (the path is, for example: secondary winding of transformer → on-switch switch → inductor L1 → load terminal F1 → center tap T3), thereby completely avoiding the huge losses caused by the current flowing through the high voltage drop diode inside the switch.

[0031] This invention utilizes a control module to pre-calculate and generate a synchronous rectification control signal that is logically completely independent of the primary-side inverter pulse width modulation signal, based on the system's input and preset output parameters. This control method does not rely on real-time detection and tracking of the primary-side switching state, thus eliminating the lag in signal generation. Furthermore, the control module is intelligently configured to keep the synchronous rectification switch in the synchronous rectification unit on during the freewheeling phase formed by the switching state of the inverter unit. This provides a path for the freewheeling current through its low-resistance conductive channel, avoiding or significantly reducing current flow through the high-loss body diode. By providing a continuous channel path, the efficiency can be improved by approximately 20% compared to existing synchronous rectification technologies. Even with high output current and high output voltage, although the freewheeling phase is relatively short, this solution can still eliminate the inherent losses during this period, achieving an efficiency improvement of approximately 2%. Compared with existing technologies, this invention breaks through the limitations of traditional follower control mode and realizes efficient and precise independent control of the rectifier circuit throughout the entire working cycle (including the freewheeling phase), which significantly improves the overall efficiency and dynamic performance of the converter under harsh conditions such as low output voltage and high current.

[0032] Example 2: See Figure 2 This embodiment discloses a full-effect synchronous rectification control method, which is applied to a full-effect synchronous rectification system. The method includes the following steps: receiving a power modulation command and acquiring input power parameters and preset power output parameters; calculating and generating logically independent inverter pulse width modulation signals and synchronous rectification control signals based on the input power parameters and preset power output parameters; sending the inverter pulse width modulation signal to the inverter unit to control the switching state of the inverter unit; sending the synchronous rectification control signal to the synchronous rectification unit to control the switching state of the synchronous rectification unit; wherein the switching state of the inverter unit forms a freewheeling phase; and, according to the synchronous rectification control signal, controlling the synchronous rectification switch in the synchronous rectification unit to conduct during the freewheeling phase, so that the freewheeling current flows through the conductive channel of the synchronous rectification switch.

[0033] Furthermore, during the freewheeling phase, the synchronous rectification control signal controls the two synchronous rectification switches in the synchronous rectification unit to be turned on simultaneously.

[0034] Furthermore, the method includes: setting the conduction time of the first inverter circuit in the inverter unit to T1, the conduction time of the second inverter circuit to T3, the first freewheeling stage time from the turn-off of the first inverter circuit to the turn-on of the second inverter circuit to T2, and the second freewheeling stage time from the turn-off of the second inverter circuit to the turn-on of the first inverter circuit to T4; and controlling the conduction time of the first synchronous rectifier switch to T1+T2+T4, and controlling the conduction time of the second synchronous rectifier switch to T3+T2+T4, thereby ensuring that both synchronous rectifier switches are in the conducting state during all freewheeling stages (T2 and T4), providing a parallel low-impedance channel path for the freewheeling current.

[0035] Based on the content and principles disclosed in the above specification, those skilled in the art can make various changes, modifications, or substitutions to the specific embodiments described above without departing from the essence and scope of the invention. Therefore, the invention is not limited to the specific embodiments and drawings disclosed herein. Any changes, equivalent substitutions, or improvements made within the scope of protection defined in the claims should be included within the scope of protection of the invention. Furthermore, although specific technical terms or expressions may be used in the specification, this is only for the purpose of facilitating description and understanding of the invention and is not intended to limit the scope of the invention. Similar or identical parts between the various embodiments in this specification can be referred to mutually; differences are emphasized in terms of improvements and beneficial effects.

Claims

1. A full-efficiency synchronous rectification system, comprising a control module and a power modulation module, wherein the power modulation module includes a DC input terminal, an inverter unit, a transformer unit, a synchronous rectification unit, and a load terminal; the synchronous rectification unit is equipped with a synchronous rectification switch; the primary windings of the DC input terminal, the inverter unit, and the transformer unit are connected in series sequentially; the secondary winding of the transformer unit, the synchronous rectification unit, and the load terminal are connected in series sequentially to form a rectified output circuit; characterized in that: The control module is connected to the control terminal of the inverter unit and the control terminal of the synchronous rectification unit respectively, so as to output an inverter pulse width modulation signal to the inverter unit and a synchronous rectification control signal to the synchronous rectification unit. The logic of the synchronous rectification control signal is independent of the logic of the inverter pulse width modulation signal. Furthermore, the control module is configured to: during the freewheeling phase, control the synchronous rectifier switch in the synchronous rectifier unit to be in the on state, so that the freewheeling current flows through the conductive channel of the synchronous rectifier switch.

2. The full-efficiency synchronous rectification system according to claim 1, characterized in that, The control module includes a digital signal processor; the digital signal processor is configured with an inverter control signal output terminal and a synchronous rectification control signal output terminal; the inverter control signal output terminal is connected to the control terminal of the inverter unit; the synchronous rectification control signal output terminal is connected to the control terminal of the synchronous rectification unit.

3. The full-efficiency synchronous rectification system according to claim 1 or 2, characterized in that, The synchronous rectification unit includes two synchronous rectification circuits. The control module calculates and generates the inverter pulse width modulation signal and the corresponding synchronous rectification control signal based on the input power parameters and the preset power output parameters. Furthermore, the control module generates a synchronous rectification control signal based on the switching logic of the inverter pulse width modulation signal, which is used to control the synchronous rectification switching transistors in the two synchronous rectification circuits to be turned on simultaneously during the freewheeling phase.

4. The full-efficiency synchronous rectification system according to claim 3, characterized in that, The control module calculates and determines the start and end times of the freewheeling phase based on the duty cycle of the inverter pulse width modulation signal and the preset dead time.

5. The full-efficiency synchronous rectification system according to claim 3, characterized in that, The inverter unit includes a first inverter circuit and a second inverter circuit that are alternately turned on, and the synchronous rectification unit includes a corresponding first synchronous rectification circuit and a second synchronous rectification circuit; within one working cycle, let the on-time of the first inverter circuit be T1, the on-time of the second inverter circuit be T3, the first freewheeling phase time from the first inverter circuit being turned off to the second inverter circuit being turned on be T2, and the second freewheeling phase time from the second inverter circuit being turned off to the first inverter circuit being turned on again be T4; The control module is configured to: control the conduction time of the synchronous rectifier switch in the first synchronous rectifier circuit to be T1+T2+T4, and control the conduction time of the synchronous rectifier switch in the second synchronous rectifier circuit to be T3+T2+T4.

6. The full-efficiency synchronous rectification system according to claim 2, characterized in that, The synchronous rectifier switch is a metal-oxide-semiconductor field-effect transistor.

7. The full-efficiency synchronous rectification system according to claim 2, characterized in that, The control module is configured to adaptively adjust the timing of the synchronous rectification control signal used to control the conduction of the freewheeling phase according to the duty cycle of the inverter pulse width modulation signal, and the duty cycle is inversely proportional to the conduction time of the synchronous rectification switch in the freewheeling phase.

8. A method for controlling a fully effective synchronous rectifier, applied to a fully effective synchronous rectifier system, characterized in that, Includes the following steps: Receive power modulation commands and obtain input power parameters and preset power output parameters; Based on the input power parameters and the preset power output parameters, calculate and generate logically independent inverter pulse width modulation signals and synchronous rectification control signals; The inverter pulse width modulation signal is sent to the inverter unit to control the switching state of the inverter unit; the synchronous rectification control signal is sent to the synchronous rectification unit to control the switching state of the synchronous rectification unit; and the switching state of the inverter unit forms a freewheeling phase. According to the synchronous rectification control signal, the synchronous rectification switch in the synchronous rectification unit is turned on during the freewheeling phase so that the freewheeling current flows through the conductive channel of the synchronous rectification switch.

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