Bidirectional multi-port wireless electric energy transmission system and control method thereof

Abstract

The invention provides a bidirectional multi-port wireless power transmission system and a control method thereof. The method comprises the following steps: controlling a first wireless transmission branch corresponding to a first port based on a duty ratio and constant frequency; acquiring alternating current side voltage and alternating current side current of a second wireless transmission branch and a third wireless transmission branch corresponding to the second port and the third port; determining active power and reactive power of the second port and the third port based on the alternating current side voltage and the alternating current side current; determining an external phase shift angle and / or an internal phase shift angle based on the active power, the reactive power, reference power and a reference phase angle; and generating a corresponding control signal based on the external phase shift angle and / or the internal phase shift angle so as to control the power flow direction and size of the second wireless transmission branch and the third wireless transmission branch.

Description

Technical Field

[0001] This disclosure relates to the field of wireless charging, and more particularly to a bidirectional multi-port wireless power transmission system and its control method. Background Technology

[0002] Existing bidirectional wireless power transfer systems typically achieve synchronization control through wireless communication between the primary and secondary controllers, transmitting relevant information from the secondary side to the primary side for voltage synchronization. However, communication delays and electromagnetic interference are significant issues, making it difficult to achieve synchronized control signals. Adding auxiliary coil detection is also impractical in multi-port systems, as the increased number of detection coils leads to more complex coupling relationships between them. Many synchronization control techniques are only suitable for two-port systems and cannot be applied to multi-port wireless power transfer systems. Therefore, bidirectional multi-port wireless power transfer systems lack effective output power control mechanisms, making it difficult to achieve free and reliable power acquisition and meet the energy regulation requirements under complex operating conditions. Summary of the Invention

[0003] This disclosure proposes a bidirectional multi-port wireless power transmission system and its control method to at least partially solve the aforementioned technical problems.

[0004] In a first aspect, this disclosure provides a control method for a bidirectional, multi-port wireless power transfer system, comprising: The first wireless transmission branch corresponding to the first port is controlled based on the constant duty cycle and frequency. Obtain the AC side voltage and AC side current of the second and third wireless transmission branches corresponding to the second and third ports; The active power and reactive power of the second port and the third port are determined based on the AC side voltage and the AC side current. The outward phase shift angle and / or inward phase shift angle are determined based on the active power, the reactive power, the reference power, and the reference phase angle; Based on the outer phase shift angle and / or inner phase shift angle, corresponding control signals are generated to control the power flow direction and magnitude of the second wireless transmission branch and the third wireless transmission branch.

[0005] According to a second aspect of this disclosure, a bidirectional multi-port wireless power transmission system is provided, wherein the first wireless transmission branch includes the first port, a first compensation topology circuit, a first active full-bridge controller, and a first DC power supply connected in series. The second wireless transmission branch includes the second port, the second compensation topology circuit, the second active full-bridge controller, and the second DC power supply connected in series. The third wireless transmission branch includes the third port, the third compensation topology circuit, the third active full-bridge controller, and the third DC power supply connected in series. The second wireless transmission branch and the third wireless transmission branch are controlled based on the method described in the first aspect.

[0006] As can be seen from the above, the bidirectional multi-port wireless power transmission system and its control method disclosed herein first employ constant duty cycle and frequency control for the first wireless transmission branch corresponding to the first port; then, the AC side voltage and current of the wireless transmission branches corresponding to the second and third ports are acquired, and their active and reactive power are determined accordingly; next, the outward phase shift angle and / or inward phase shift angle are calculated by combining the reference power and reference phase angle; finally, a control signal is generated to control the power flow direction and magnitude of the second and third wireless transmission branches. This system can precisely regulate the power flow between multiple ports, achieving efficient bidirectional energy transmission and rational distribution, improving system stability and flexibility, and adapting to the power transmission needs of multiple devices under different operating conditions. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in this disclosure or related technologies, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a schematic diagram of a rotating transmitter for related technologies.

[0009] Figure 2 This is a schematic diagram of the interference observation method of related technologies.

[0010] Figure 3 This is a schematic diagram of synchronous control based on resonant current tracking, a related technology.

[0011] Figure 4 This is a schematic diagram of power control in related technologies.

[0012] Figure 5 This is a schematic diagram of a power droop control strategy in related technologies.

[0013] Figure 6 This is a schematic diagram of time-division wireless power transfer in related technologies.

[0014] Figure 7 This is a schematic diagram of wireless power transfer using multiple inverters in related technologies.

[0015] Figure 8This is a flowchart illustrating a control method for a bidirectional multi-port wireless power transmission system according to an embodiment of the present disclosure.

[0016] Figure 9 This is a schematic diagram of synchronization control according to an embodiment of the present disclosure.

[0017] Figure 10 This is a schematic diagram of power control according to an embodiment of the present disclosure.

[0018] Figure 11 This is a schematic diagram of a bidirectional multi-port wireless power transmission system according to an embodiment of the present disclosure.

[0019] Figure 12 This is an equivalent circuit diagram of the LCC compensation structure according to an embodiment of the present disclosure.

[0020] Figure 13 This is a phasor diagram of the circuit variables in an embodiment of this disclosure.

[0021] Figure 14 This is a schematic diagram of the control strategy according to an embodiment of the present disclosure. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0023] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this disclosure should have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms "first," "second," and similar terms used in the embodiments of this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0024] Among related technologies, the rapid development of power electronics technology has provided a highly efficient and highly controllable power transmission method for the application of wireless power transfer systems. Magnetic coupling resonant wireless power transfer technology, due to its non-electrical connection characteristics, makes power supply flexible, safe, and reliable, and has become a research hotspot in recent years. Today, wireless power transfer technology has been widely used in many fields such as portable electronics, electric vehicles, biomedicine, and aerospace. Bidirectional wireless power transfer technology has more advantages than traditional unidirectional wireless power transfer technology, enabling the mutual flow of energy between the "source" and the "load".

[0025] In bidirectional wireless power transfer systems, synchronization control has become a key focus in research and application, playing a crucial role in efficient and stable energy exchange. Currently, research on multi-port bidirectional wireless power transfer is limited, making the design of appropriate system structures and the adoption of reasonable control strategies paramount. In applications such as dynamic wireless power supply, constant-power wireless charging, and adjustable power supply, stable and controllable output power is essential for ensuring system performance and user experience. Bidirectional energy transfer between multiple ports increases the system's coupling complexity; without an effective output power control mechanism, achieving free and reliable energy acquisition becomes difficult. Therefore, precise and effective control strategies are necessary to meet the energy flow requirements between different ports. This not only ensures stable power transfer under various operating conditions but also enhances the system's adaptability and reliability, thereby promoting the practical application and development of wireless power transfer technology in more fields.

[0026] Some technologies employ a strategy of arranging different numbers of receivers in the same plane within a multi-load WPT system to ensure that each load always receives the same output power. For example, an omnidirectional WPT system based on a rotating transmitter can provide uniform and synchronous power to multiple surrounding loads. However, this system requires an additional motor to drive and control the rotation of the transmitter, such as... Figure 1 As shown, Figure 1 A schematic diagram of a rotating transmitter based on related technology is shown. Synchronization control can be achieved through interference observation methods. Interference is applied to the relative phase shift angle: if the power changes in the desired direction, the relative phase shift angle will continue to increase or decrease in the same direction; otherwise, it will change in the opposite direction. Figure 2 As shown, Figure 2 A schematic diagram of the interference observation method of related technologies is shown. The maximum (or minimum, depending on the power flow direction) of the resonant current can be tracked by the relationship between the resonant current of the secondary-side converter and the relative phase difference, realizing a synchronous control strategy without auxiliary hardware and real-time communication, such as... Figure 3 As shown, Figure 3A schematic diagram of synchronous control based on resonant current tracking based on related technologies is shown. For power control, phase-shift control strategies are typically used for power flow control in a double-sided full-bridge converter topology BWPT system. Taking an SS-type full-bridge converter topology BWPT system as an example, the DC input voltages on the primary and secondary sides are Vd and Vo, respectively. The primary and secondary converters generate internal phase shift angles φ1 and φ2 to adjust the output voltage, such as... Figure 4 As shown, Figure 4 A schematic diagram of power control in related technologies is shown. A control strategy based on power-frequency droop characteristics is proposed for LCL-type BWPT systems, such as... Figure 5 As shown, Figure 5 A schematic diagram of a power droop control strategy in related technologies is shown. The system power is linearly related to frequency during forward or reverse transmission; however, when the driving frequency deviates from the system's resonant frequency, the system's reactive power increases, leading to a decrease in system transmission efficiency.

[0027] For power distribution, a time-division multiplexing approach can be used to allocate power among loads. This involves continuously switching the compensation capacitor array at the transmitter and applying excitation at corresponding frequencies, supplying power to a single target load at any given moment. The ratio of output power to energy transmission time for each load is equal. Figure 6 As shown, Figure 6 A schematic diagram of time-sharing wireless power transfer in related technologies is shown. Multiple inverters with different frequencies can also be superimposed to drive a multi-frequency excitation source, such as... Figure 7 As shown, Figure 7 A schematic diagram of multi-inverter superimposed wireless power transfer in related technologies is shown.

[0028] However, existing technologies for wireless power transfer systems with bidirectional energy flow between multiple ports are rarely studied. Synchronization control in existing bidirectional wireless power transfer systems is typically achieved through wireless communication between the primary and secondary controllers, transmitting relevant information from the secondary side to the primary side for voltage synchronization. However, communication delays and electromagnetic interference are significant, making it difficult to synchronize control signals. Adding auxiliary coil detection also greatly reduces practicality in multi-port systems. The increased number of detection coils in multi-port systems leads to more complex coupling relationships between coils. Many synchronization control techniques are only suitable for two-port systems and cannot be applied to multi-port systems. By optimizing the coil arrangement and structure to create a more uniform magnetic field environment, the coil structure design in bidirectional multi-port wireless power transfer systems must meet power requirements—that is, power can be transmitted bidirectionally and its magnitude is controllable. Traditional control methods are insufficient to meet the energy regulation requirements under complex operating conditions.

[0029] Therefore, improving the control efficiency and control effect of bidirectional multi-port wireless power transmission systems has become an urgent technical problem to be solved.

[0030] In view of this, this disclosure provides a bidirectional multi-port wireless power transfer system and its control method. First, the first wireless transmission branch corresponding to the first port is controlled with constant duty cycle and frequency. Then, the AC side voltage and current of the wireless transmission branches corresponding to the second and third ports are acquired, and their active and reactive power are determined accordingly. Next, the outward and / or inward phase shift angles are calculated by combining reference power and reference phase angle. Finally, a control signal is generated to control the power flow direction and magnitude of the second and third wireless transmission branches. This system can precisely regulate the power flow between multiple ports, achieving efficient bidirectional energy transfer and rational distribution, improving system stability and flexibility, and adapting to the power transfer needs of multiple devices under different operating conditions.

[0031] See Figure 8 , Figure 8 A flowchart illustrating a control method for a bidirectional multi-port wireless power transfer system according to an embodiment of the present disclosure is shown. The parameter optimization method 800 for a permanent magnet synchronous motor may further include the following steps.

[0032] In step S810, the first wireless transmission branch corresponding to the first port is controlled based on the duty cycle and constant frequency.

[0033] Specifically, for the first wireless transmission branch corresponding to the first port, a control method with a fixed duty cycle and frequency can be adopted, that is, keeping the proportion of the on-time of the switching devices in this branch and the oscillation frequency of the signal constant. This simplifies the control strategy, reduces the complexity and cost of the control system, and enables the first wireless transmission branch to operate in a stable state, providing a reliable energy transmission foundation channel for the entire system. Specifically, the duty cycle refers to the ratio of the on-time of the switching device to the total time of the entire switching cycle. When the duty cycle is constant, it means that the ratio of the on-time to the off-time of the switching device is fixed. For example, if the duty cycle is set to 50%, the on-time and off-time of the switching device are equal in one switching cycle. By keeping the duty cycle constant, the relative proportion of energy transmission time and interruption time in the first wireless transmission branch can be controlled, thereby stabilizing the output characteristics of this branch to a certain extent. Frequency refers to the number of times the switching device switches per unit time. A constant frequency ensures that the switching device performs on and off operations at a fixed rate. In wireless power transmission systems, frequency stability is crucial for the generation and coupling of magnetic fields. A stable frequency allows the transmitting coil to generate a stable alternating magnetic field, which is beneficial for the magnetic resonance coupling between the receiving coil and the transmitting coil, ensuring the stability of energy transmission.

[0034] In step S820, the AC side voltage and AC side current of the second wireless transmission branch and the third wireless transmission branch corresponding to the second port and the third port are obtained; the first port, the second port and the third port are coupled to each other.

[0035] In a bidirectional multi-port wireless power transmission system where the first, second, and third ports are coupled together, the voltage and current parameters of the AC side of the wireless transmission branches corresponding to the second and third ports are obtained. This provides a key basis for subsequent operations such as power analysis of the second and third ports, helps to accurately grasp the energy transmission status of these two ports, and thus enables effective monitoring and control of energy flow between the multiple ports of the entire system, thereby improving the stability and efficiency of system operation.

[0036] Specifically, a suitable AC voltage sensor can be selected based on the system's voltage level and accuracy requirements. For example, for systems with lower voltage levels, a resistive voltage divider sensor can be used, which proportionally converts high voltage to low voltage for measurement through a precision resistor network. For high voltage systems or systems with extremely high accuracy requirements, an electromagnetic voltage transformer is a better choice, as it can accurately convert the high voltage on the primary side to the standard low voltage on the secondary side according to the transformation ratio. The selected voltage sensor should be correctly installed on the AC side of the second and third wireless transmission branches, ensuring a good connection to the circuit and compliance with safety regulations. A suitable AC current sensor can be selected based on the system's current magnitude and measurement requirements. For example, a current transformer, based on the principle of electromagnetic induction, can convert a large current on the primary side into a small current on the secondary side for measurement according to the transformation ratio; Hall effect current sensors have advantages such as fast response speed, high accuracy, and the ability to measure both DC and AC currents, making them suitable for systems with high dynamic performance requirements. The current sensor should be connected in series in the AC side lines of the second and third wireless transmission branches, ensuring a secure installation and avoiding problems such as poor contact.

[0037] Voltage and current sensors convert detected AC voltage and current physical quantities into measurable electrical signals (usually voltage signals). The built-in circuitry of these sensors performs preliminary processing on the converted signals, such as amplification and filtering, to improve signal quality and stability. For example, amplification circuits can amplify weak sensor output signals to a level suitable for subsequent processing; filtering circuits can remove high-frequency noise and interference from the signal. The processed voltage and current signals are transmitted to the data acquisition system via shielded cables or other suitable transmission media. Shielded cables effectively reduce the impact of external electromagnetic interference on the signal, ensuring the accuracy of signal transmission. Based on the acquired voltage and current data, the active and reactive power of the second and third ports can be calculated. Then, combined with reference power and reference phase angle, the outward and / or inward phase shift angles are determined, generating control signals to control the power flow direction and magnitude of the second and third wireless transmission branches, achieving efficient and stable system operation.

[0038] In step S830, the active power and reactive power of the second port and the third port are determined based on the AC side voltage and the AC side current.

[0039] After acquiring the AC side voltage and current data of the corresponding wireless transmission branches at the second and third ports, the instantaneous values ​​of the AC side voltage and current are substituted into specific formulas using relevant power calculation theories and methods, or their waveforms are analyzed and processed, such as by sampling and calculating the voltage and current signals using digital signal processing technology, to determine the active and reactive power of these two ports respectively. This provides a clear understanding of the energy transmission and exchange at the second and third ports. It offers crucial information for subsequent system control based on power demand, helping to rationally allocate energy, optimize system operation, improve energy transmission efficiency, and ensure the stability and high efficiency of the bidirectional multi-port wireless power transmission system.

[0040] Specifically, in the time domain, for a single-phase AC circuit, the instantaneous value of the AC side voltage... u ( t )=2 U sin( ωt + φu Instantaneous current value i ( t )=2 I sin( ωt + φi ),in U , I These are the effective values ​​of voltage and current, respectively. ω Angular frequency, φu , φi These represent the initial phases of the voltage and current, respectively. Instantaneous power. p (t )= u ( t ) i ( t ), which can be obtained by expanding using trigonometric functions. p ( t )= UI cos( φ )− UI cos(2 ωt +2 φi - φu + φi )(in φ = φu - φi The active power is the average value of the instantaneous power over one cycle, while the reactive power is related to the effective values ​​of voltage and current, as well as the sinusoidal value of the phase difference between them.

[0041] In step S840, the outward phase shift angle and / or inward phase shift angle are determined based on the active power, the reactive power, the reference power, and the reference phase angle.

[0042] Based on the calculated active and reactive power of the second and third ports, combined with pre-set reference power and reference phase angle, and according to a specific power control strategy and mathematical model, a series of calculations and analyses are performed to determine the outer and / or inner phase shift angles that can meet the system's power transmission requirements. Determining the phase shift angle enables precise control over the direction and magnitude of power flow in the second and third wireless transmission branches, ensuring that the actual power at the ports matches the reference power, improving the system's ability to regulate power distribution, ensuring stable and efficient system operation, and enhancing the system's adaptability to different operating conditions.

[0043] In some embodiments, determining the outward phase shift angle and / or the inward phase shift angle based on the active power, the reactive power, the reference power, and the reference phase angle includes: The actual phase angle is determined based on the active power and the reactive power; The outward shift phase angle is obtained by performing proportional-integral processing based on the phase angle difference between the actual phase angle and the reference phase angle; Generate the corresponding frequency signal based on the intermediate phase angle; The outward phase shift angle is obtained by converting the frequency signal.

[0044] The process involves first calculating the actual phase angle based on the active and reactive power obtained from the second and third ports, then calculating the difference between the actual phase angle and the preset reference phase angle, and performing proportional-integral processing on this difference to obtain the outward phase angle. Simultaneously, a corresponding frequency signal is generated based on the intermediate related calculation steps, and this frequency signal is then converted to obtain the outward phase angle.

[0045] Specifically, such as Figure 9 As shown, Figure 9 A schematic diagram of synchronization control according to an embodiment of the present disclosure is shown. Figure 9 The diagram illustrates the control structure of a phase-locked loop (PLL), which can be used to synchronize and track the phase and frequency of an input signal. It can be based on a given reference phase signal. θreference and feedback signals from the port θpower Phase angle error Δ θ This feedback signal θpower It can be calculated based on the active power P and reactive power Q at the port. The phase angle error Δ... θ The signal is fed into a PI (Proportional-Integral) controller. The PI controller generates a control signal based on the magnitude and rate of change of the error signal, which is used to adjust the output frequency of the voltage-controlled oscillator (VCO). The output frequency of the VCO is proportional to the input control voltage. The VCO adjusts its output angular frequency according to the output signal from the PI controller. ωs Angular frequency of VCO output ωs Converted into a phase signal by a converter (e.g., an integrator). θg This is because frequency is the derivative of phase, and integration can convert a frequency signal into a phase signal. The converted phase signal... θg It may pass through a phase delay module to adjust the phase to match the reference phase. In this way, by continuously adjusting the VCO's output frequency, the internally generated phase is... θg With reference phase θreference Maintaining synchronization. The role of the PI controller is to quickly and stably eliminate phase errors, ensuring the synchronization accuracy and stability of the system. This structure is widely used in communication systems, power electronics, and other fields to achieve precise phase and frequency synchronization.

[0046] In some embodiments, determining the outward phase shift angle and / or the inward phase shift angle based on the active power, the reactive power, the reference power, and the reference phase angle includes: Based on the active power and the reference power, the power error is obtained; The inner phase shift angle is obtained by performing proportional-integral processing based on the power error.

[0047] First, the power error is calculated based on the actual active power of the second or third port and a pre-set reference power. Then, this power error is processed using a proportional-integral (PI) control algorithm to obtain the inner phase shift angle. By determining the inner phase shift angle in this way, dynamic adjustments can be made based on the deviation between the actual power and the reference power at the port, achieving precise control of the port power. This allows the actual power to track the reference power quickly and stably, improving the accuracy and response speed of the system's power control and ensuring the efficient and stable operation of the system.

[0048] Specifically, such as Figure 10 As shown, Figure 10 A schematic diagram of power control according to an embodiment of the present disclosure is shown. Figure 10 In the middle, the reference power Pref Actual feedback power at the port P The power error is calculated through comparison, reflecting the deviation between the actual power and the desired power. This power error is input to a PI (Proportional-Integral) controller. Based on the magnitude and rate of change of the error, the PI controller generates a control signal—the inner phase shift angle—through proportional and integral actions. The proportional action responds quickly to changes in the error, while the integral action eliminates steady-state errors, ensuring the system reaches and maintains the setpoint. The inner phase shift angle signal output by the PI controller is transmitted to the converter. The converter adjusts its output based on this phase shift angle signal, thereby controlling power transmission parameters such as the phase relationship of voltage and current, influencing the actual power output. The converter's output effect is reflected in the actual power output. P Feedback is sent back to the system, along with the reference power. Pref The comparison is repeated to form a closed-loop control system. By continuously adjusting the inner phase shift angle, the system can dynamically adjust the actual power, gradually bringing it closer to and stabilizing it at the reference power. Pref The set value is determined by the control process, which uses a closed-loop feedback mechanism and the adjustment of the PI controller and the inner phase angle to achieve precise power control and ensure stable and efficient system operation.

[0049] In step S850, a corresponding control signal is generated based on the outer phase shift angle and / or inner phase shift angle to control the power flow direction and magnitude of the second wireless transmission branch and the third wireless transmission branch.

[0050] Based on the determined outer and / or inner phase shift angles, the phases are converted into electrical signals of a specific format or conforming to equipment requirements, serving as control signals. These control signals are then transmitted to the relevant control components of the second and third wireless transmission branches, such as switching devices or regulating devices. Based on the phase information of the phase shift angles, the phase relationship of voltage and current in the branches is adjusted, thereby controlling the direction and magnitude of power flow. This enables flexible and precise control of the power in the second and third wireless transmission branches, allowing for dynamic adjustment of power flow direction and value according to system requirements. It optimizes energy distribution among multiple ports, improves the overall energy transmission efficiency and stability of the system, and ensures reliable operation of the bidirectional multi-port wireless power transmission system under various operating conditions.

[0051] In some embodiments, generating a corresponding control signal based on the outer phase shift angle and / or inner phase shift angle includes: The outward phase angle is frequency-converted to generate a corresponding frequency signal; Phase-shift control and signal modulation are performed based on the frequency signal to generate a first control signal to control the direction and magnitude of the power flow.

[0052] The process involves first converting the determined external phase shift angle into a corresponding frequency signal using a specific conversion mechanism. Then, based on this frequency signal, phase shift control and signal modulation operations are performed to generate a first control signal, which is used to precisely regulate the power flow direction and magnitude of the second or third wireless transmission branch. This effectively converts the external phase shift angle into a directly usable control signal, enabling flexible and precise control of the power flow direction and magnitude. This helps optimize the energy distribution of multi-port wireless power transmission systems, improving the system's adaptability to different operating conditions and overall transmission efficiency.

[0053] In some embodiments, generating a corresponding control signal based on the outer phase shift angle and / or inner phase shift angle includes: Phase-shift control and signal modulation are performed based on the inner phase-shift angle to generate a second control signal to control the power level.

[0054] Based on a predetermined inner phase shift angle, phase-shift control is implemented in relevant control circuits or algorithms. Further signal modulation is then performed to transform the control information contained in the inner phase shift angle into a second control signal with appropriate parameters and waveforms. This signal is then used to precisely regulate the power of the second or third wireless transmission branch. This effectively applies the inner phase shift angle to power control, enabling flexible and precise adjustment of the power of the wireless transmission branch. This helps meet the power requirements of the system under different loads and operating conditions, improving the stability and energy transmission efficiency of the multi-port wireless power transmission system.

[0055] This disclosure also provides a bidirectional multi-port wireless power transmission system, wherein the first wireless transmission branch includes the first port, a first compensation topology circuit, a first active full-bridge controller, and a first DC power supply connected in series. The second wireless transmission branch includes the second port, the second compensation topology circuit, the second active full-bridge controller, and the second DC power supply connected in series. The third wireless transmission branch includes the third port, the third compensation topology circuit, the third active full-bridge controller, and the third DC power supply connected in series. The second wireless transmission branch and the third wireless transmission branch are controlled based on the method described in the embodiments of this disclosure.

[0056] The first wireless transmission branch consists of a first port, a first compensation topology circuit, a first active full-bridge controller, and a first DC power supply connected in series. The second and third wireless transmission branches have similar structures, each consisting of a corresponding port, a compensation topology circuit, an active full-bridge controller, and a DC power supply connected in series. The second and third wireless transmission branches are regulated using the control method mentioned in the embodiments of this disclosure. This enables flexible wireless power transmission between multiple ports, allowing for precise control of the power flow direction and magnitude of each branch according to requirements, improving energy transmission efficiency, enhancing the system's adaptability to different loads and operating conditions, and ensuring stable and reliable system operation.

[0057] Specifically, such as Figure 11 As shown, Figure 11 A schematic diagram of a bidirectional multi-port wireless power transfer system according to an embodiment of the present disclosure is shown. Figure 11 The bidirectional multi-port wireless power transfer system comprises multiple coupled branches. Each branch includes: a DC power supply, an active full-bridge controller, a compensation topology circuit, coupling coils and controllers, a control module, and a sampling module. The DC power supply provides the initial electrical input for the entire wireless power transfer system, serving as its foundation. Active full-bridge controllers are installed in port 1, port 2, and port 3 loops. These controllers convert and control the input DC power, transforming it into AC power suitable for wireless transmission. They can also adjust parameters such as the phase and amplitude of the output voltage and current based on control signals, thereby controlling the direction and magnitude of power flow. Each port loop is connected to a compensation topology circuit, used to compensate and adjust parameters such as inductance and capacitance to improve transmission efficiency, power factor, and stability, reduce reactive power loss, and ensure efficient operation under various load conditions. The coupling coils, through electromagnetic induction, wirelessly transfer energy from the transmitting coil of one port to the receiving coil of another, achieving contactless power transfer. The sampling module, in its control and sampling modules, is responsible for real-time sampling and monitoring of various parameters in the system, such as voltage, current, and power, and feeding this data back to the control module. The control module, based on the sampled data and preset control strategies, calculates the corresponding control signals and sends them to the active full-bridge controller to achieve precise control of the system's power transmission. Furthermore, the control module also has functions such as calculating reactive and reactive power transmission characteristics and generating control signals using a VCO (Voltage-Controlled Oscillator), further optimizing system performance. Through the coordinated work of these components, the system achieves bidirectional wireless power transmission between multiple ports and can flexibly control the direction and magnitude of power flow according to actual needs, offering advantages such as high efficiency, flexibility, and stability.

[0058] In some embodiments, the first compensation topology circuit, the second compensation topology circuit, and the third compensation topology circuit are LCC resonant compensation structures; The first active full-bridge controller operates in inverter mode, while the second and third active full-bridge controllers operate in rectifier mode. The first port includes a first coil L1 and a first parasitic resistance R1 connected in series; the second port includes a second coil L2 and a second parasitic resistance R2; and the third port includes a third coil L3 and a third parasitic resistance R3. The first coil L1, the second coil L2, and the third coil L3 are coupled to each other, and a first mutual inductance M exists between the first coil L1 and the second coil L2. 12 There is a second mutual inductance M between the first coil L1 and the third coil L3. 13 A third mutual inductance M exists between the second coil L2 and the third coil L3. 23 ; The first compensation topology circuit includes a first compensation capacitor C1 and a first resonant capacitor C. f1 and the first resonant inductor L f1 The first resonant capacitor C connected in series f1 The first compensation capacitor C1, the first coil L1, and the first parasitic resistor R1 are connected to the first active full-bridge controller; the first resonant capacitor C f1 One end is connected to the first resonant inductor L f1 Between the first compensation capacitor C1 and the first resonant capacitor C f1 The other end is connected between the first parasitic resistor R1 and the first active full-bridge controller; The second compensation topology circuit includes a second compensation capacitor C2 and a second resonant capacitor C. f2 Second resonant inductor L f2 The second resonant capacitor C connected in series f2 The second compensation capacitor C2, the second coil L2, and the second parasitic resistor R2 are connected to the second active full-bridge controller; the second resonant capacitor C f2 One end is connected to the second resonant inductor L f2 Between the second compensation capacitor C2, the second resonant capacitor C f2 The other end is connected between the second parasitic resistor R2 and the second active full-bridge controller; The third compensation topology circuit includes a third compensation capacitor C3 and a third resonant capacitor C. f3 and the third resonant inductor L f3 The third resonant capacitor C connected in series f3The third compensation capacitor C3, the third coil L3, and the third parasitic resistor R3 are connected to the third active full-bridge controller; the third resonant capacitor C f3 One end is connected to the third resonant inductor L f3 Between the third compensation capacitor C3 and the third resonant capacitor C f3 The other end is connected between the third parasitic resistor R3 and the third active full-bridge controller.

[0059] Among them, such as Figure 12 As shown, Figure 12 An equivalent circuit diagram of an LCC compensation structure according to an embodiment of the present disclosure is shown. Figure 12 In this system, the controller can be placed at ports 2 and 3. Power control is achieved by collecting the active and reactive power transmission characteristics at these two ports. The control signal for port 1 uses a square wave signal with a constant duty cycle and frequency for open-loop control. The control signals for ports 2 and 3 are adjusted according to actual needs to ensure power flows as required. An LCC resonant compensation structure is chosen, allowing energy to flow bidirectionally between the three ports. Therefore, the compensation topology is designed as a completely symmetrical structure, consisting of H-bridge units and an LCC hybrid compensation network. When a port is used as a source, the corresponding H-bridge unit functions as a high-frequency inverter; if the port is used as a load, the H-bridge unit becomes a high-frequency controlled rectifier. The circuit equivalent diagram of this system is shown below. Figure 1 As shown, L1, L2, and L3 are the self-inductances of the coil, R1, R2, and R3 are the parasitic resistances of the coil, and M... 12 M 13 M 23 For the mutual inductance between coils, L f1 L f2 L f3 For resonant inductance, C f1 C1, C f2 C2, C f3 C3 is a compensation capacitor. U 1. U 2 and U 3 represents the equivalent AC voltage at each port. I 1. I 2. I 3 represents the coil current. I f1 , I f2 , I f3 It is the resonant inductor current.

[0060] In some embodiments, the AC equivalent voltages of the first port, the second port, and the third port are: ; Wherein, U1, U2, and U3 are the equivalent AC voltage values ​​of the first port, the second port, and the third port, and V1, V2, and V3 are the AC voltage amplitudes of the first port, the second port, and the third port. α , β γ is the inner phase shift angle of the first wireless transmission branch, the second wireless transmission branch, and the third wireless transmission branch. φ , ψ The phase shift angle is the outer angle of the second wireless transmission branch and the third wireless transmission branch.

[0061] Specifically, the formula for calculating the AC equivalent voltage at the three ports is as follows: (1) As shown in (1), the magnitude of the equivalent AC voltage can be adjusted by the inner phase shift, while the phase angle between the equivalent AC voltages is determined by the outer phase shift. Therefore, both the inner and outer phase shifts are suitable for power control of a three-port WPT system.

[0062] according to Figure 1 The KVL equations can be written as follows: (2) in, (3) Substituting the resonance condition into equation (2), we get:

[0063] As can be seen from equation (4), when the system is in resonance state, the coil current is related to the equivalent AC voltage and resonant inductance of each port, and always lags behind the corresponding equivalent AC voltage by 90°.

[0064] According to equation (5), the power at each port can be derived:

[0065] The power expressions for the three ports are shown in equation (6), where S1, S2, and S3 are the power of the first port, the second port, and the third port, respectively, and ω is the angular frequency. From this, the energy flow relationship between the different ports can be derived. Taking the first port as an example, its active power P1 can be expressed as:

[0066] From equation (7), the active power P1 consists of three parts:

[0067] Among them, P 12 It represents the energy flow relationship between port 1 and port 2, and is independent of the circuit parameters of port 3; similarly, P13 It represents the energy flow relationship between port 1 and port 3, and is independent of the circuit parameters of port 2; P 01 It is the power generated by the resistance of port 1 itself.

[0068] In some embodiments, the first port operates in power source mode, and the second port and the third port operate in load mode; when At that time, U1 leads U2 in phase, and the first electrical energy P transmitted between the first port and the second port... 12 If the value is greater than zero, the first port will transfer power to the second port; when... U1 phase lags behind U2, the first electrical energy P 12 When the value is less than zero, power is transferred from the second port to the first port; when At that time, U1 leads U3 in phase, and the second electrical energy P transmitted between the first port and the third port... 13 If the value is greater than zero, the first port will transfer power to the third port; when... U1 phase lags behind U3, the second electrical energy P 13 If the value is less than zero, power is transferred from the third port to the first port.

[0069] Specifically, such as Figure 13 As shown, Figure 13 A phasor diagram of circuit variables according to an embodiment of the present disclosure is shown. Figure 13 In the middle, when At that time, U1 leads U2 in phase, P 12 When the value is greater than zero, port 1 will transfer power to port 2. Conversely, when... That is, the phase of U1 lags behind that of U2, P 12 When the value is less than zero, power is transferred from port 2 to port 1. Similarly, P 13 Its flow direction can also be controlled by the outward phase shift ψ. In summary, the power magnitude and power flow direction can be adjusted by modulating the outward phase shift angle between any two ports, and the port with the leading voltage phase always transmits power to the lagging port. At the same time, according to (1) and (8), P 12 and P 13 It is also related to the internal phase shift angles α and β. Therefore, it is feasible to adjust the transmitted power through internal phase shifting, but adjusting the internal phase shift angle can only control the power magnitude; the direction of power flow can only be determined by external phase shifting. Therefore, a dual-phase shifting control method can be used to control both the direction and magnitude of power flow in the system. The control strategy is as follows: Figure 14 As shown. Figure 14First, the high-frequency voltage and current output from the inverters on ports 2 and 3 are acquired, and the active and reactive power transmission characteristics of the system are calculated using a multiplier. The power waveforms of both are then low-pass filtered and fed into the sampling port of the DSP, where they are processed by the program to obtain the system's control signals. By setting different power reference values ​​and different power angles, the magnitude and direction of energy flow are controlled.

[0070] As can be seen, this disclosure places the control circuit at the second port 2 and the third port 3 to achieve stable operation of the bidirectional three-port wireless power transmission system. Compared with the traditional method, this disclosure places the control circuit on one side, which can effectively solve the influence of communication delay in the synchronization signal. By applying control to the system according to the phase angle relationship of energy flow between the three ports, energy interconnection between the three ports can be realized, improving the efficiency and effect of bidirectional energy flow between multiple ports.

[0071] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this disclosure (including the claims) is limited to these examples; within the framework of this disclosure, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the embodiments of this disclosure as described above, which are not provided in detail for the sake of brevity.

[0072] Additionally, to simplify the description and discussion, and to avoid obscuring the embodiments of this disclosure, the provided drawings may or may not show well-known power / ground connections to integrated circuit (IC) chips and other components. Furthermore, the apparatus may be shown in block diagram form to avoid obscuring the embodiments of this disclosure, and this also takes into account the fact that the details of implementation of these block diagram apparatuses are highly dependent on the platform on which the embodiments of this disclosure will be implemented (i.e., these details should be fully understood by those skilled in the art). While specific details (e.g., circuits) have been set forth to describe exemplary embodiments of this disclosure, it will be apparent to those skilled in the art that the embodiments of this disclosure can be implemented without these specific details or with variations thereof. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0073] Although this disclosure has been described in conjunction with specific embodiments thereof, many substitutions, modifications, and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may be used with the embodiments discussed.

[0074] This disclosure is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A control method for a bidirectional multi-port wireless power transfer system, characterized in that, include: The first wireless transmission branch corresponding to the first port is controlled based on the constant duty cycle and frequency. Obtain the AC side voltage and AC side current of the second and third wireless transmission branches corresponding to the second and third ports; the first port, the second port, and the third port are coupled to each other; The active power and reactive power of the second port and the third port are determined based on the AC side voltage and the AC side current. The outward phase shift angle and / or inward phase shift angle are determined based on the active power, the reactive power, the reference power, and the reference phase angle; Based on the outer phase shift angle and / or inner phase shift angle, corresponding control signals are generated to control the power flow direction and magnitude of the second wireless transmission branch and the third wireless transmission branch.

2. The method according to claim 1, characterized in that, Determining the outward and / or inward phase shift angles based on the active power, the reactive power, the reference power, and the reference phase angle includes: The actual phase angle is determined based on the active power and the reactive power; The outward shift phase angle is obtained by performing proportional-integral processing based on the phase angle difference between the actual phase angle and the reference phase angle; Generate the corresponding frequency signal based on the intermediate phase angle; The outward phase shift angle is obtained by converting the frequency signal.

3. The method according to claim 2, characterized in that, Based on the outer phase shift angle and / or inner phase shift angle, a corresponding control signal is generated, including: The outward phase angle is frequency-converted to generate a corresponding frequency signal; Phase-shift control and signal modulation are performed based on the frequency signal to generate a first control signal to control the direction and magnitude of the power flow.

4. The method according to claim 1, characterized in that, Determining the outward and / or inward phase shift angles based on the active power, the reactive power, the reference power, and the reference phase angle includes: Based on the active power and the reference power, the power error is obtained; The inner phase shift angle is obtained by performing proportional-integral processing based on the power error.

5. The method according to claim 4, characterized in that, Based on the outer phase shift angle and / or inner phase shift angle, a corresponding control signal is generated, including: Phase-shift control and signal modulation are performed based on the inner phase-shift angle to generate a second control signal to control the power level.

6. A bidirectional, multi-port wireless power transmission system, characterized in that, The first wireless transmission branch includes the first port, the first compensation topology circuit, the first active full-bridge controller, and the first DC power supply connected in series. The second wireless transmission branch includes the second port, the second compensation topology circuit, the second active full-bridge controller, and the second DC power supply connected in series. The third wireless transmission branch includes the third port, the third compensation topology circuit, the third active full-bridge controller, and the third DC power supply connected in series. The second wireless transmission branch and the third wireless transmission branch are controlled based on the method described in any one of claims 1-5.

7. The system according to claim 6, characterized in that, The first compensation topology circuit, the second compensation topology circuit, and the third compensation topology circuit are LCC resonant compensation structures; The first active full-bridge controller operates in inverter mode, while the second and third active full-bridge controllers operate in rectifier mode. The first port includes a first coil L1 and a first parasitic resistance R1 connected in series; the second port includes a second coil L2 and a second parasitic resistance R2; and the third port includes a third coil L3 and a third parasitic resistance R3. The first coil L1, the second coil L2, and the third coil L3 are coupled to each other, and a first mutual inductance M exists between the first coil L1 and the second coil L2. 12 There is a second mutual inductance M between the first coil L1 and the third coil L3. 13 A third mutual inductance M exists between the second coil L2 and the third coil L3. 23 ; The first compensation topology circuit includes a first compensation capacitor C1 and a first resonant capacitor C. f1 and the first resonant inductor L f1 The first resonant capacitor C connected in series f1 The first compensation capacitor C1, the first coil L1, and the first parasitic resistor R1 are connected to the first active full-bridge controller; the first resonant capacitor C f1 One end is connected to the first resonant inductor L f1 Between the first compensation capacitor C1 and the first resonant capacitor C f1 The other end is connected between the first parasitic resistor R1 and the first active full-bridge controller; The second compensation topology circuit includes a second compensation capacitor C2 and a second resonant capacitor C. f2 Second resonant inductor L f2 The second resonant capacitor C connected in series f2 The second compensation capacitor C2, the second coil L2, and the second parasitic resistor R2 are connected to the second active full-bridge controller; the second resonant capacitor C f2 One end is connected to the second resonant inductor L f2 Between the second compensation capacitor C2, the second resonant capacitor C f2 The other end is connected between the second parasitic resistor R2 and the second active full-bridge controller; The third compensation topology circuit includes a third compensation capacitor C3 and a third resonant capacitor C. f3 and the third resonant inductor L f3 The third resonant capacitor C connected in series f3 The third compensation capacitor C3, the third coil L3, and the third parasitic resistor R3 are connected to the third active full-bridge controller; the third resonant capacitor C f3 One end is connected to the third resonant inductor L f3 Between the third compensation capacitor C3 and the third resonant capacitor C f3 The other end is connected between the third parasitic resistor R3 and the third active full-bridge controller.

8. The system according to claim 7, characterized in that, The AC equivalent voltages of the first port, the second port, and the third port are: ； Wherein, U1, U2, and U3 are the equivalent AC voltage values ​​of the first port, the second port, and the third port, and V1, V2, and V3 are the AC voltage amplitudes of the first port, the second port, and the third port. α , β γ is the inner phase shift angle of the first wireless transmission branch, the second wireless transmission branch, and the third wireless transmission branch. φ , ψ The phase shift angle is the outer angle of the second wireless transmission branch and the third wireless transmission branch.

9. The system according to claim 8, characterized in that, Also includes: Based on the AC equivalent voltages of the first port, the second port, and the third port, the power of the corresponding port is determined, including: Wherein, S1, S2, and S3 are the power of the first port, the second port, and the third port, respectively, and ω is the angular frequency.

10. The system according to claim 8, characterized in that, Also includes: The first port operates in power source mode, while the second and third ports operate in load mode. when At that time, U1 leads U2 in phase, and the first electrical energy P transmitted between the first port and the second port... 12 If the value is greater than zero, the first port will transfer power to the second port; when... U1 phase lags behind U2, the first electrical energy P 12 When the value is less than zero, power is transferred from the second port to the first port; when At that time, U1 leads U3 in phase, and the second electrical energy P transmitted between the first port and the third port... 13 If the value is greater than zero, the first port will transfer power to the third port; when... U1 phase lags behind U3, the second electrical energy P 13 If the value is less than zero, power is transferred from the third port to the first port.

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