Soft-switching bridgeless circuit based on wireless power transmission and control method

Abstract

This invention discloses a soft-switching bridgeless circuit and its control method based on wireless power transfer. The soft-switching bridgeless circuit includes a primary-side excitation module, a wireless power transfer module, a soft-switching bridgeless rectifier module, and a low-pass filter connected in sequence. The primary-side excitation module provides high-frequency excitation to the primary side of the wireless power transfer module; the wireless power transfer module enables wireless power transfer; the soft-switching bridgeless rectifier module performs soft-switching bridgeless rectification on the output of the wireless power transfer module; and the low-pass filter filters the output of the soft-switching bridgeless rectifier module. This invention features a simple structure and novel control method. The soft-switching bridgeless circuit and its control method based on wireless power transfer can be widely applied in various applications of wireless DC output, such as wireless charging.

Description

Technical Field

[0001] This invention relates to the fields of wireless power transmission and power electronics, and in particular to a soft-switching bridgeless circuit and control method based on wireless power transmission. Background Technology

[0002] Currently, there has been considerable research on soft-switching in wireless power transfer, many of which focus on soft-switching of the excitation source. For example, Zhang Shaoteng, Zhao Jinbin, Wu Yuebao, et al., “Research on Soft-Switching Technology of Class E Inverters for Wireless Power Transfer Based on Self-Inductance Regulation,” *Journal of Electrical Engineering*, Vol. 36, No. 21, 2018.07, pp:4558-4566. Some studies utilize special circuit topologies to construct soft-switching circuits, such as Huang Jun, He Xuguo, Huo Pengchong, “Research on Soft-Switching Optimization Control of LCC-LCC Type Bidirectional Wireless Power Transfer System Based on Modal Analysis,” *Proceedings of the Chinese Society for Electrical Engineering*, [OL], http: / / kns.cnki.net / kcms / detail / 11.2107.TM.20220803.1712.017.html. Bridgeless circuits are often used for power factor correction to improve system efficiency. Some researchers have studied soft-switching bridgeless circuits, such as Zhang Qingchuan, Yang Limin, Wang Shuai, and Liu Xuandong, "Design of High Power Factor Soft-Switching Buck Bridgeless PFC Converter," *Power Electronics Technology*, Vol. 56, No. 1, 2022.01, pp:103-106. Generally, soft-switching implementation requires hardware circuitry. Rectifier circuit control is mostly based on traditional PWM control.

[0003] Currently, there are no reports on the application of soft-switching bridgeless circuits to wireless power transfer. Summary of the Invention

[0004] The first objective of this invention is to provide a soft-switching bridgeless circuit based on wireless power transmission.

[0005] The second objective of this invention is to provide a control method for a soft-switching bridgeless circuit based on wireless power transmission.

[0006] The first objective of this invention is achieved as follows:

[0007] The soft-switching bridgeless circuit based on wireless power transfer is characterized by comprising a primary-side excitation module, a wireless power transfer module, a soft-switching bridgeless rectifier module, and a low-pass filter connected in sequence. The input side of the primary-side excitation module is the power supply, and the output side of the primary-side excitation module is connected to the primary-side input side of the wireless power transfer module. The secondary-side output side of the wireless power transfer module is connected to the input terminal of the soft-switching bridgeless rectifier module, and the output terminal of the soft-switching bridgeless rectifier module is connected to the input terminal of the low-pass filter. The low-pass filter is the output of the soft-switching bridgeless circuit based on wireless power transfer of this invention, outputting the desired DC power.

[0008] Primary-side excitation module: Enables high-frequency excitation of the primary side of the wireless power transmission module;

[0009] Wireless power transfer module: Enables wireless power transfer;

[0010] Soft-switching bridgeless rectifier module: Implements soft-switching bridgeless rectifier output for the output stage of the wireless power transfer module;

[0011] Low-pass filter: Filters the output of the soft-switching bridgeless rectifier module.

[0012] The soft-switching bridgeless rectifier module is composed of a full-bridge circuit consisting of power electronic switches S1 to S4.

[0013] The circuit topology selection of the wireless power transmission module is based on actual needs and is not limited to a specific topology type. It includes four basic topologies: series-parallel, series-series, parallel-series, and parallel-parallel, as well as a multi-coil topology.

[0014] The circuit topology of the low-pass filter is selected according to actual needs and is not limited to a specific topology type. The selection includes LC low-pass filters, LCL filters, and composite filters, etc. The output terminal of the low-pass filter is the output terminal of the circuit of the present invention.

[0015] The second objective of this invention is achieved as follows:

[0016] The control method for a soft-switching bridgeless circuit based on wireless power transmission is characterized by: controlling the soft-switching bridgeless rectifier module composed of power electronic switches S1-S4, and using a zero-crossing interception method to achieve soft switching and DC voltage output control, thereby realizing DC output.

[0017] This invention employs a soft-switching bridgeless rectifier control based on a high-frequency input primary-side excitation module. The soft-switching bridgeless rectifier module has four operating conditions: forward conduction, forward freewheeling, reverse conduction, and reverse freewheeling.

[0018] Definition: The frequency of a wireless power transfer module is... f RThe output voltage of the wireless power transfer module is u R .

[0019] This invention uses a soft-switching bridgeless rectifier module for... u R Perform forward and reverse rectification, and both forward and reverse rectification are performed within... u R The switching on or off of power electronic switches S1-S4 is controlled at the zero-crossing point. Since the switching on or off of power electronic switches S1-S4 all occur at zero voltage, zero-voltage soft switching is achieved. DC output voltage U O Regulation is achieved by controlling power electronic switches S1-S4.

[0020] Preferably, the present invention can also control the output voltage of the wireless power transfer module by adjusting the primary-side excitation module. u R The amplitude, thereby implementing the DC output voltage U of the entire system circuit. O control.

[0021] This invention reduces the number of uncontrolled rectifier stages in the wireless power transmission stage by employing a bridgeless design, effectively lowering power loss and improving system efficiency. Furthermore, the output voltage control of this invention is not traditional PWM control, but rather uses a zero-crossing interception method to achieve soft switching, reducing switching losses and further lowering power loss and improving efficiency. This invention features a simple structure and novel control mechanism.

[0022] The present invention, based on a soft-switching bridgeless circuit and control method for wireless power transmission, can be widely applied in various applications of wireless DC output, such as wireless charging. Attached Figure Description

[0023] Figure 1 This is a circuit structure block diagram of the present invention;

[0024] Figure 2 This is the main circuit topology diagram of the soft-switching bridgeless rectifier module of the present invention;

[0025] Figure 3 The following are equivalent circuit diagrams for four operating conditions of the soft-switching bridgeless rectifier module: a is the forward conduction diagram, b is the forward freewheeling diagram, c is the reverse conduction diagram, and d is the reverse freewheeling diagram.

[0026] Figure 4 This is a schematic diagram of the soft-switching control of a soft-switching bridgeless rectifier module, where: a is the input of the soft-switching bridgeless rectifier module. u R The waveform diagram is shown in Figure 1, and Figure 2 is the waveform diagram of the output U of the soft-switching bridgeless rectifier module.

[0027] Figure 5This is the main circuit of a MOSFET-based soft-switching bridgeless rectifier module.

[0028] Figure 6 Output voltage for wireless power transfer module u R A schematic diagram of amplitude changes. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the embodiments and the accompanying drawings.

[0030] Figure 1 This is a circuit structure block diagram of the present invention.

[0031] This embodiment of a soft-switching bridgeless circuit based on wireless power transfer includes a primary-side excitation module, a wireless power transfer module, a soft-switching bridgeless rectifier module, and a low-pass filter connected in sequence. The input side of the primary-side excitation module is the power supply, and the output side of the primary-side excitation module is connected to the primary-side input side of the wireless power transfer module. The secondary-side output side of the wireless power transfer module is connected to the input terminal of the soft-switching bridgeless rectifier module, and the output terminal of the soft-switching bridgeless rectifier module is connected to the input terminal of the low-pass filter. The low-pass filter is the output of the soft-switching bridgeless circuit based on wireless power transfer of this invention, outputting the desired DC power.

[0032] Primary-side excitation module: Enables high-frequency excitation of the primary side of the wireless power transmission module; the primary-side excitation module is not limited to a specific circuit topology, and the specific selection depends on the actual needs.

[0033] Wireless power transfer module: Enables wireless power transfer; The circuit topology of the wireless power transfer module is selected based on actual needs and is not limited to a specific topology type. It includes four basic topologies: series-parallel, series-series, parallel-series, and parallel-parallel, as well as multi-coil topologies.

[0034] Soft-switching bridgeless rectifier module: Implements soft-switching bridgeless rectification output for the output of the wireless power transfer module; The soft-switching bridgeless rectifier module is composed of a full-bridge circuit consisting of power electronic switches S1~S4, with high-frequency input at the input end and DC output at the output end.

[0035] Low-pass filter: filters the output of the soft-switching bridgeless rectifier module; the selection of the low-pass filter circuit topology is based on actual needs and is not limited to a specific topology type. The selection includes LC low-pass filter, LCL filter and composite filter, etc. The output terminal of the low-pass filter is the output terminal of the circuit of this invention.

[0036] The control method of the soft-switching bridgeless circuit based on wireless power transmission is to control the soft-switching bridgeless rectifier module composed of power electronic switches S1-S4, and to achieve DC output by using the zero-crossing interception method to realize soft switching and DC voltage output control.

[0037] Figure 2 This is the main circuit topology diagram of the soft-switching bridgeless rectifier module of the present invention.

[0038] The soft-switching bridgeless rectifier module in this embodiment consists of a bridgeless rectifier circuit composed of power electronic switches S1-S4, with input terminal AB being a high-frequency input. u R The output terminal CD is a DC output U.

[0039] Figure 3 This is the equivalent circuit for four operating conditions of a soft-switching bridgeless rectifier module.

[0040] This invention employs soft-switching bridgeless rectifier control based on high-frequency input. The soft-switching bridgeless rectifier module has four operating modes: forward conduction, forward freewheeling, reverse conduction, and reverse freewheeling. Forward conduction and forward freewheeling constitute forward rectification, and reverse conduction and reverse freewheeling constitute reverse rectification. Bridgeless rectified output is achieved by controlling the switching of these four operating modes of the soft-switching bridgeless rectifier module.

[0041] Figure 3 -(a) represents the input voltage of the soft-switching bridgeless rectifier module. u R When positive, the equivalent circuit is forward-conducting.

[0042] Forward Guidance: u R When the condition is positive, power electronic switches S1 and S4 are turned on, and the current flows through A→S1→C→D→S4→B. The soft-switching bridgeless rectifier module operates in the forward conduction condition.

[0043] Figure 3 -(b) represents the input voltage of the soft-switching bridgeless rectifier module. u R When the circuit is positive, the equivalent circuit for forward freewheeling is used. The soft-switching bridgeless rectifier module operates in the forward freewheeling condition.

[0044] Positive Continuation: u R When the signal is positive, power electronic switches S2 and S4 are turned on, and current flows through C→D→S4→S2.

[0045] Figure 3 -(c) represents the input voltage of the soft-switching bridgeless rectifier module. u R When the value is negative, the reverse conduction equivalent circuit soft-switching bridgeless rectifier module operates in reverse conduction mode.

[0046] Reverse guidance: u R When the value is negative, power electronic switches S2 and S3 are turned on, and the current flows through B→S2→C→D→S3→A.

[0047] Figure 3 -(d) represents the input voltage of the soft-switching bridgeless rectifier module. u R When the value is negative, the reverse freewheeling equivalent circuit soft-switching bridgeless rectifier module operates in reverse freewheeling mode.

[0048] Reverse continuous flow: u R When the value is negative, power electronic switches S1 and S3 are turned on, and current flows through C→D→S3→S1.

[0049] Figure 4 This is a schematic diagram of the soft-switching control of a soft-switching bridgeless rectifier module.

[0050] The DC output voltage U of the present invention O Regulation is achieved by controlling the soft-switching bridgeless rectifier module. u R For both forward and reverse rectification, the soft-switching bridgeless rectifier module uses a half-wave truncation method for control. This means a complete sine half-wave is used as a basic control unit, and an integer number of sine half-waves are truncated for each control cycle. Furthermore, both forward and reverse rectification are performed within... u R At the zero-crossing moment, the power electronic switches S1-S4 are turned on or off to achieve zero-voltage soft switching.

[0051] Figure 4 Example provided. Figure 4 Figure a shows the input of the soft-switching bridgeless rectifier module. u R waveform, Figure 4 Figure b shows the waveform of the output U of the soft-switching bridgeless rectifier module. The control points are all located at... u R At the zero-crossing moment, zero-voltage switching can be achieved, i.e., zero-voltage soft switching.

[0052] Figure 5 This is the main circuit of a MOSFET-based soft-switching bridgeless rectifier module.

[0053] When the power electronic switch in the soft-switching bridgeless rectifier module adopts a MOSFET-based solution, the main circuit is... Figure 5 As shown.

[0054] The power electronic switches S1-S4 are all composed of two identical metal-oxide-semiconductor field-effect transistors (MOSFETs) connected in reverse series. That is, the gate of the upper transistor is connected to the gate of the lower transistor, the source of the upper transistor is connected to the source of the lower transistor, and the drain of the upper transistor and the drain of the lower transistor are the main current ports, sharing the gate drive of the two transistors.

[0055] Taking S1 as an example, when a drive signal is applied to the drive terminal G1, S1 is turned on, and current can flow through S1; conversely, S1 is turned off. The control of the other power electronic switches S2, S3, and S4 is exactly the same as that of S1, and will not be described in detail. In practical applications, power electronic switches S1-S4 can also be constructed using other schemes, such as insulated gate bipolar transistors (IGBTs), wide bandgap devices (gallium nitride (GaN) devices, or silicon carbide (SiC) devices.

[0056] Figure 6 Output voltage for wireless power transfer module u R A schematic diagram illustrating the dynamic changes in amplitude.

[0057] Preferably, the output voltage U of the present invention O The output voltage of the wireless power transfer module can also be controlled by adjusting the primary-side excitation module. u R The amplitude, thereby implementing the DC output voltage U of the entire system circuit. O Control. At different times. u R The amplitude can be dynamically changed as needed. For example, the output voltage U O If it is too small, increase u R Amplitude; Output voltage U O If it is too large, reduce it. u R Amplitude.

[0058] In specific control operations, if frequency conversion is required for the primary-side excitation module and the wireless power transfer module, it can be achieved by adjusting the primary-side excitation module. u R DC output voltage U is implemented in the manner of amplitude. O Control. The control method can be used as the output voltage U. O The main control method can also be used as an auxiliary control method.

[0059] The above description discloses only specific embodiments of the present invention, but the present invention is not limited thereto. Those skilled in the art can make various modifications and variations to the present invention without departing from its spirit and scope. Obviously, all such modifications and variations should fall within the protection scope claimed by the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any special limitation on the present invention.

Claims

1. A control method for a soft-switching bridgeless circuit based on wireless power transfer, characterized in that: The soft-switching bridgeless circuit based on wireless power transfer includes a primary-side excitation module, a wireless power transfer module, a soft-switching bridgeless rectifier module, and a low-pass filter connected in sequence. The input side of the primary-side excitation module is the power supply, and the output side of the primary-side excitation module is connected to the primary-side input side of the wireless power transfer module. The secondary-side output side of the wireless power transfer module is connected to the input terminal of the soft-switching bridgeless rectifier module, and the output terminal of the soft-switching bridgeless rectifier module is connected to the input terminal of the low-pass filter. The output of the low-pass filter is the output of the soft-switching bridgeless circuit based on wireless power transfer, which outputs the desired DC power. Primary-side excitation module: Enables high-frequency excitation of the primary side of the wireless power transmission module; Wireless power transfer module: Enables wireless power transfer; Soft-switching bridgeless rectifier module: Implements soft-switching bridgeless rectifier output for the output stage of the wireless power transfer module; Low-pass filter: filters the output of the soft-switching bridgeless rectifier module; The control method for a soft-switching bridgeless circuit based on wireless power transfer is as follows: By controlling the soft-switching bridgeless rectifier module composed of power electronic switches S1-S4, a zero-crossing interception method is used to achieve soft switching and DC voltage output control, thus realizing DC output; the DC output voltage U... O Adjustment is achieved by controlling the soft-switching bridgeless rectifier module; the soft-switching bridgeless rectifier module is used for... u R Forward and reverse rectification are performed; that is, the control of the soft-switching bridgeless rectifier module adopts a half-wave truncation method. Specifically, a complete sine half-wave is used as a basic control unit, and an integer number of sine half-waves are truncated for each control cycle. This applies to both forward and reverse rectification. u R At the zero-crossing moment, the power electronic switches S1-S4 are turned on or off to achieve zero-voltage soft switching. in: u R Output voltage for the wireless power transfer module; The soft-switching bridgeless rectifier module is a bridgeless rectifier circuit composed of power electronic switches S1-S4. The input terminal AB is a high-frequency input, and the output terminal CD is a DC output. Power electronic switches S1 and S3 form one bridge arm, and power electronic switches S2 and S4 form the other bridge arm. The input terminal A is connected to the common terminal of power electronic switches S1 and S3, and the input terminal B is connected to the common terminal of power electronic switches S2 and S4. The common terminal after connecting the other end of power electronic switch S1 and the other end of power electronic switch S2 is the output terminal C, and the common terminal after connecting the other end of power electronic switch S3 and the other end of power electronic switch S4 is the output terminal D. The soft-switching bridgeless rectifier module has four operating modes: forward conduction, forward freewheeling, reverse conduction, and reverse freewheeling. Forward conduction and forward freewheeling constitute forward rectification, and reverse conduction and reverse freewheeling constitute reverse rectification. Bridgeless rectification output is achieved by controlling the switching of the four operating modes of the soft-switching bridgeless rectifier module. Forward Guidance: u R When the condition is positive, power electronic switches S1 and S4 are turned on, and the current flows through A→S1→C→D→S4→B. The soft-switching bridgeless rectifier module operates in the forward conduction condition. Positive Continuation: u R When the signal is positive, power electronic switches S2 and S4 are turned on, and current flows through C→D→S4→S2; Reverse guidance: u R When the value is negative, power electronic switches S2 and S3 are turned on, and the current flows through B→S2→C→D→S3→A; Reverse continuous flow: u R When the value is negative, power electronic switches S1 and S3 are turned on, and current flows through C→D→S3→S1.

2. The control method for a soft-switching bridgeless circuit based on wireless power transfer according to claim 1, characterized in that: The circuit topology of the wireless power transmission module includes four basic topologies: series-parallel, series-series, parallel-series, and parallel-parallel, as well as a multi-coil topology.

3. The control method for a soft-switching bridgeless circuit based on wireless power transfer according to claim 1, characterized in that: The power electronic switches S1-S4 use insulated gate bipolar transistors (IGBTs), wide bandgap devices (gallium nitride GaN devices or silicon carbide SiC devices).

4. The control method for a soft-switching bridgeless circuit based on wireless power transfer according to claim 1, characterized in that: The circuit topology of the low-pass filter includes an LC low-pass filter, an LCL filter, and a composite filter. The output terminal of the low-pass filter is the output terminal of the soft-switching bridgeless circuit based on wireless power transmission.

5. The control method for a soft-switching bridgeless circuit based on wireless power transfer according to claim 1, characterized in that: Output voltage U O The output voltage of the wireless power transfer module is controlled by adjusting the primary-side excitation module. u R The amplitude, thereby implementing the DC output voltage U of the entire system circuit. O Control; under different time periods u R The amplitude changes dynamically as needed; when the output voltage U O If it is too small, increase u R Amplitude; when the output voltage U O If it is too large, reduce it. u R Amplitude.

6. The control method for a soft-switching bridgeless circuit based on wireless power transfer according to claim 5, characterized in that: When the primary-side excitation module and the wireless power transfer module perform frequency conversion, the primary-side excitation module is adjusted to change... u R DC output voltage U is implemented in the manner of amplitude. O Control; the control method is output voltage U O The main control method or the auxiliary control method.

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