A phase-locked method and system for active rectification of wireless power transfer systems
By performing analog-to-digital conversion and compensation control on the rectifier input current, high-precision phase-locked loop (PLL) for wireless power transmission systems is achieved, solving the problems of low reliability and accuracy of PLL in existing technologies. It is applicable to various resonant topologies and simplifies hardware circuit design.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XI AN JIAOTONG UNIV
- Filing Date
- 2022-07-27
- Publication Date
- 2026-05-15
AI Technical Summary
Existing high-frequency phase-locked loop (PLL) technology for wireless power transmission systems suffers from low reliability and accuracy, especially in bilateral LCC or LCL topologies, where existing methods are subject to pulse loss, complex hardware circuitry, and high design difficulty.
By performing analog-to-digital conversion on the rectifier input current, the component containing phase information is obtained. Phase-locked loop (PLL) is achieved using a compensation controller and a carrier comparison value, avoiding reliance on zero-crossing detection of the resonant current. The PLL system is designed using a modular approach.
It improves the accuracy and reliability of rectifier input voltage and current phase detection, simplifies hardware circuit design, is applicable to various resonant topologies, and has strong scalability.
Smart Images
Figure CN115133793B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of wireless power transmission technology and relates to a phase-locked method and system for active rectification in wireless power transmission systems. Background Technology
[0002] Compared to traditional wired charging, wireless power transfer technology offers numerous advantages, including flexibility, ease of use, reduced maintenance, adaptability to harsh environments, and ease of achieving unmanned automatic and mobile power supply. Typically, wireless charging systems not only require constant voltage and current control but also high transmission efficiency.
[0003] To improve the charging efficiency of wireless power transfer systems, active rectification is a common technique. Active rectification not only increases the system's control freedom but also reduces the conduction losses of passive rectification. It allows control of the system's output voltage and current without introducing an additional DC / DC converter by controlling the duty cycle of the active rectifier's input voltage and the phase difference between the input voltage and current. The key to the stable operation of the active rectification system is reliable high-frequency phase-locked loop (PLL) technology; however, existing PLL technologies have several problems. The most common existing zero-crossing detection-based PLL method suffers from pulse loss, leading to false triggering of the drive pulse, and is unsuitable for wireless charging systems with bilateral LCC or LCL resonant topologies. In bilateral LCC or LCL resonant topologies, the resonant current contains a large number of high-order harmonics, resulting in severe current distortion and potentially detecting multiple zero-crossing points in a single cycle, thus generating erroneous drive signals. To avoid this, existing technologies propose a synchronization method based on an auxiliary detection coil, where the primary-side main coil current is detected and used as a synchronization source for the secondary-side drive signal. However, this detection method requires a large auxiliary measuring coil and is easily affected by the current in the secondary main coil. To eliminate the influence of the main coil current on the detection, a precise compensation circuit needs to be designed, which significantly increases the difficulty of hardware circuit design. Furthermore, in recent years, an active rectification technology based on the detection of active and reactive power at the rectifier input has been proposed. This technology calculates the phase difference between the current input voltage and current by detecting the magnitude of the active and reactive power at the rectifier input. However, the hardware circuit for detecting active and reactive power is too complex, and the detection value of the reactive power detection circuit is affected by the high-order harmonic components in the resonant current, thus affecting the reliability and accuracy of high-frequency phase-locked loops. Summary of the Invention
[0004] The purpose of this invention is to solve the problems of low reliability and accuracy of high-frequency phase-locked loops in the prior art, and to provide a phase-locked loop method and system for active rectification in wireless power transmission systems.
[0005] To achieve the above objectives, the present invention employs the following technical solution:
[0006] This invention proposes a phase-locked loop method for active rectification in a wireless power transmission system, comprising the following steps:
[0007] The rectifier input current value is fed into the signal conditioning circuit to obtain the first and second components containing phase information. The first component is converted from analog to digital to obtain the third component, and the second component is converted from analog to digital to obtain the fourth component.
[0008] The first compensated value is obtained based on the third component, the rectifier output voltage, and the resonant network parameters; the second compensated value is obtained based on the second component, the rectifier output voltage, and the resonant network parameters.
[0009] The phase sampling value between the fundamental component of the current rectifier input voltage and the fundamental component of the rectifier input current is obtained based on the first and second compensated values.
[0010] The phase difference is obtained based on the phase reference value command and the phase sampling value. The phase difference is input into the compensation controller of the controller to output the carrier comparison value. The drive signal of the power tube in the rectifier is obtained based on the carrier comparison value and the triangular carrier, so as to realize the phase lock of active rectification.
[0011] Preferably, the third component The expression is as follows:
[0012]
[0013] in, Input resonant current to the rectifier. For power transistors Q A square wave of driving pulse voltage of 1. Let t be the system's operating cycle, and t be the time variable.
[0014] Preferably, the fourth component The expression is as follows:
[0015]
[0016] in, Input resonant current to the rectifier. For power transistors Q The square wave signal obtained after delaying the driving pulse of 1 by T / 4 cycles.
[0017] Preferably, the influence of harmonic components in the rectifier input current on the first and second components is compensated by the controller.
[0018] Preferably, the value after the first compensation The expression is as follows:
[0019]
[0020] in, The third component, The duty cycle of the rectifier input voltage. To determine the input impedance corresponding to the third harmonic of the resonant network from the rectifier end, This refers to the third harmonic component in the rectifier input voltage. The fifth harmonic component in the rectifier input voltage. The third harmonic component in the input resonant current of the rectifier. The fifth harmonic component in the input resonant current of the rectifier. For power transistors Q 1 is a square wave of driving pulse voltage.
[0021] Preferably, the second compensation value The expression is as follows:
[0022]
[0023] in, The fourth component, This represents the duty cycle of the rectifier input voltage.
[0024] Preferably, the third harmonic component in the rectifier input resonant current The expression is as follows:
[0025]
[0026] The fifth harmonic component in the rectifier input resonant current The expression is as follows:
[0027]
[0028] in, This is the DC-side output voltage. This refers to the third harmonic component in the rectifier input voltage. To determine the input impedance corresponding to the fifth harmonic component of the resonant network from the rectifier end, Secondary main coil inductance L s With compensation inductance value The ratio between them This is the system's operating angular frequency.
[0029] Preferably, the phase sampling value between the fundamental component of the rectifier input voltage and the fundamental component of the rectifier input current φ The expression is as follows:
[0030]
[0031] in, This is the value after the first compensation. This is the value after the second compensation.
[0032] Preferably, the method for obtaining the drive signal of the power transistor in the rectifier based on the carrier comparison value and the triangular carrier is as follows:
[0033] Based on carrier comparison value A, carrier comparison value B is obtained. When carrier comparison value B equals the triangular carrier value, the drive pulse is set to zero, generating the power transistor in the active rectifier. Q 1 is the drive signal;
[0034] power transistor Q 2 with power transistor Q The drive signals of 1 are complementary, resulting in the power transistor. Q 2. Drive signal;
[0035] For power transistors Q 1 drive signal delay β s T Time, to obtain the power transistor Q 3. Drive signal;
[0036] power transistor Q 4 with power transistors Q The drive signals of 3 are complementary, resulting in the power transistor. Q 4. Drive signal.
[0037] This invention proposes a phase-locked loop system for active rectification in a wireless power transmission system, comprising:
[0038] The first parameter acquisition module is used to import the rectifier input current value into the signal conditioning circuit, acquire the first component and the second component containing phase information, perform analog-to-digital conversion on the first component to obtain the third component, and perform analog-to-digital conversion on the second component to obtain the fourth component.
[0039] The second parameter acquisition module is used to obtain the first compensated value based on the third component, the rectifier output voltage, and the resonant network parameters; and to obtain the second compensated value based on the second component, the rectifier output voltage, and the resonant network parameters.
[0040] The third parameter acquisition module is used to obtain the phase sampling value between the fundamental component of the current rectifier input voltage and the fundamental component of the rectifier input current based on the first compensated value and the second compensated value.
[0041] The drive signal acquisition module is used to obtain the phase difference based on the phase reference value command and the phase sampling value, input the phase difference into the compensation controller of the controller to output the carrier comparison value, and obtain the drive signal of the power tube in the rectifier based on the carrier comparison value and the triangular carrier to realize the phase lock of active rectification.
[0042] Compared with the prior art, the present invention has the following beneficial effects:
[0043] This invention proposes a phase-locked loop (PLL) method for active rectification in a wireless power transmission system. Compared to PLL methods that detect the active and reactive power inputs of the rectifier, this method is simpler to implement. Analog-to-digital conversion is performed on the first and second components to facilitate subsequent calculations. The phase between the fundamental components of the rectifier input voltage and the fundamental components of the rectifier input current is obtained by acquiring the first and second compensated values. The phase difference obtained from the feedback phase value and the phase reference value command is input into the compensation controller of the controller, which outputs a carrier comparison value. The carrier comparison value is then used to obtain the drive signal for the power transistors in the rectifier, thus achieving phase-locking of the active rectification. The PLL technology proposed in this method improves the system's accuracy in detecting the phase between the rectifier input voltage and the rectifier input current. This PLL method does not rely on zero-crossing detection of the resonant current, avoiding the instability problems caused by zero-crossing detection of the resonant current in traditional synchronization methods. Therefore, the phase-locked loop method proposed in this invention can solve the problems of low reliability and accuracy of high-frequency phase-locked loops in the prior art. This phase-locked loop method can be used in a variety of resonant topologies, has strong scalability, and has good application prospects in the field of wireless power transmission technology.
[0044] Furthermore, the phase between the rectifier input voltage and the rectifier input current is obtained by performing an orthogonal decomposition operation on the detected resonant current, which does not rely on the detection of the zero-crossing point of the resonant current, thus increasing the reliability of the phase-locked loop method. The orthogonal decomposition operation on the detected resonant current is implemented through hardware circuitry. First, the sampled resonant current is directly multiplied by the drive signal and then integrated to obtain the component. The multiplication is achieved through a multiplier, and the integration is achieved through a low-pass filter circuit.
[0045] Furthermore, the first component is obtained by multiplying the driving pulse by the sampled resonant current after a 1 / 4 cycle delay, and then integrating the result. The multiplication is achieved by a multiplier, and the integration is achieved by a low-pass filter circuit.
[0046] The present invention proposes a phase-locked loop system for active rectification in a wireless power transmission system. By dividing the system into a first parameter acquisition module, a second parameter acquisition module, a third parameter acquisition module, and a drive signal acquisition module, the modular approach makes each module independent of the others, facilitating unified management of each module. Attached Figure Description
[0047] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0048] Figure 1 This is a flowchart of the phase-locked loop method for active rectification in a wireless power transmission system according to the present invention.
[0049] Figure 2 This is a structural diagram of the wireless charging system based on a bilateral LCC compensated resonant network in this invention.
[0050] Figure 3 The waveforms of the driving pulse, rectifier input voltage, and rectifier input current of the active rectifier in the wireless charging system of this invention are shown.
[0051] Figure 4 This is a hardware circuit diagram for phase detection in this invention.
[0052] Figure 5 This is the phase-locked control diagram of the present invention.
[0053] Figure 6 The steady-state simulation waveforms of the input voltage and current of the rectifier in the system are shown in the figure when the phase-locked loop is stable according to the present invention.
[0054] Figure 7 For the phase-locked loop of the present invention to be stable, I d1 Steady-state simulation waveform.
[0055] Figure 8 For the phase-locked loop of the present invention to be stable, I q1 Steady-state simulation waveform.
[0056] Figure 9 The experimental waveforms of the input voltage and current of the rectifier in the system of this invention are shown.
[0057] Figure 10 This is a diagram of the phase-locked loop system for active rectification in a wireless power transmission system according to the present invention. Detailed Implementation
[0058] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0059] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.
[0060] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0061] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0062] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.
[0063] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.
[0064] The present invention will now be described in further detail with reference to the accompanying drawings:
[0065] This invention proposes a phase-locked loop method for active rectification in wireless power transmission systems, such as... Figure 1 As shown, it includes the following steps:
[0066] S1. Input the rectifier input current value into the signal conditioning circuit, obtain the first component and the second component containing phase information, perform analog-to-digital conversion on the first component to obtain the third component, and perform analog-to-digital conversion on the second component to obtain the fourth component.
[0067] Third component The expression is as follows:
[0068]
[0069] in, Input resonant current to the rectifier. For power transistors Q A square wave of driving pulse voltage of 1. Let t be the system's operating cycle, and t be the time variable.
[0070] Fourth component The expression is as follows:
[0071]
[0072] in, Input resonant current to the rectifier. For power transistors Q The square wave signal obtained after delaying the driving pulse of 1 by T / 4 cycles.
[0073] S2. Obtain the first compensated value based on the third component, the rectifier output voltage, and the resonant network parameters; obtain the second compensated value based on the second component, the rectifier output voltage, and the resonant network parameters.
[0074] The controller compensates for the influence of harmonic components in the rectifier input current on the first and second components.
[0075] The value after first compensation The expression is as follows:
[0076]
[0077] in, The third component, The duty cycle of the rectifier input voltage. To determine the input impedance corresponding to the third harmonic of the resonant network from the rectifier end, This refers to the third harmonic component in the rectifier input voltage. The fifth harmonic component in the rectifier input voltage. The third harmonic component in the input resonant current of the rectifier. The fifth harmonic component in the input resonant current of the rectifier. For power transistors Q1 is a square wave of driving pulse voltage.
[0078] Second compensation value The expression is as follows:
[0079]
[0080] in, The fourth component, This represents the duty cycle of the rectifier input voltage.
[0081] Third harmonic component in the rectifier input resonant current The expression is as follows:
[0082]
[0083] The fifth harmonic component in the rectifier input resonant current The expression is as follows:
[0084]
[0085] in, This is the DC-side output voltage. This refers to the third harmonic component in the rectifier input voltage. To determine the input impedance corresponding to the fifth harmonic component of the resonant network from the rectifier end, Secondary main coil inductance L s With compensation inductance value The ratio between them This is the system's operating angular frequency.
[0086] S3. Obtain the phase sampling value between the fundamental component of the current rectifier input voltage and the fundamental component of the rectifier input current based on the first compensated value and the second compensated value.
[0087] Phase sampling value between the fundamental component of the rectifier input voltage and the fundamental component of the rectifier input current φ The expression is as follows:
[0088]
[0089] in, This is the value after the first compensation. This is the value after the second compensation.
[0090] S4. Based on the phase reference value command and the phase sampling value, the phase difference is obtained. The phase difference is input into the compensation controller of the controller to output the carrier comparison value. Based on the carrier comparison value and the triangular carrier, the drive signal of the power tube in the rectifier is obtained to realize the phase lock of active rectification.
[0091] The method for obtaining the drive signal of the power transistor in the rectifier based on the carrier comparison value and the triangular carrier is as follows:
[0092] Based on carrier comparison value A, carrier comparison value B is obtained. When carrier comparison value B equals the triangular carrier value, the drive pulse is set to zero, generating the power transistor in the active rectifier. Q 1 is the drive signal;
[0093] power transistor Q 2 with power transistor Q The drive signals of 1 are complementary, resulting in the power transistor. Q 2. Drive signal;
[0094] For power transistors Q 1 drive signal delay β s T Time, to obtain the power transistor Q 3. Drive signal;
[0095] power transistor Q 4 with power transistors Q The drive signals of 3 are complementary, resulting in the power transistor. Q 4. Drive signal.
[0096] This invention proposes a phase-locked loop method for active rectification in wireless power transmission systems, such as... Figure 2 As shown, the wireless power transfer system in this invention is divided into two parts: the wireless charging system main circuit and the system phase-locked loop (PLL) control circuit. The wireless charging system main circuit mainly consists of three parts: a high-frequency inverter circuit, a resonant network, and a rectifier circuit. Each inverter and rectifier has four power transistors: S1-S4 and Q1-Q4. The inverter converts the DC input voltage into a high-frequency square wave to excite the resonant network. The AC current flowing through the coil generates a high-frequency magnetic field, which in turn induces a high-frequency voltage in the secondary coil, thereby transferring energy from the primary side to the secondary side. Finally, the rectifier converts the high-frequency resonant current into DC current. The system PLL control unit mainly includes two parts: a phase detection hardware circuit based on current orthogonal decomposition and a system controller unit.
[0097] The power transistor drive waveform of the active rectifier in this invention, and the relationship between the rectifier input voltage and input current are as follows: Figure 3 As shown. The phase detection hardware circuit in the method of this invention is as follows. Figure 4As shown, the rectifier input current is first sampled by a current sampling circuit and then sent to the signal conditioning circuit. In the first signal conditioning circuit, the sampled rectifier input current is directly multiplied by the rectifier drive signal and then low-pass filtered to obtain the first and second components containing phase information. Specifically: the drive pulse of the upper bridge arm is multiplied by the sampled rectifier input current, and the multiplication is implemented by a multiplication circuit. The output value of the multiplication circuit is sent to the low-pass filter circuit to obtain the first component. The sampled rectifier input current is multiplied by the drive pulse delayed by T / 4 cycles, and the output value of the multiplier circuit is sent to the low-pass filter circuit to obtain the second component. The first component is then converted from analog to digital to obtain the third component. I d The fourth component is obtained by performing an analog-to-digital conversion on the second component. I q ;
[0098] Third component I d and the fourth component I q The value can be calculated using the following formula:
[0099]
[0100]
[0101] in, I rs (t) represents the rectifier input resonant current, U PWMA1 For power transistors Q The driving pulse voltage square wave is 1, where T is the system operating period, t represents the time variable, and U 1 PWMA1 For power transistors Q The square wave signal obtained after delaying the driving pulse of 1 by T / 4 cycles.
[0102] The third component I obtained in the previous step is sampled by the ADC module. d and the fourth component I q The third component I obtained by sampling d and the fourth component I q The data is fed into the controller. To eliminate the influence of higher harmonic components in the resonant current on the first and second components, and to improve the system's accuracy in detecting the phase between the rectifier input voltage and the rectifier input current, the controller compensates for the influence of harmonic components in the rectifier input current on the first and second components. The first compensated value is calculated by sampling the rectifier output voltage, the third component, and the resonant network parameters. I d2The second compensated value is calculated by sampling the rectifier output voltage, the fourth component, and the resonant network parameters. I q2 .
[0103] The value after first compensation I d2 The value after second compensation I q2 The value can be calculated using the following formula:
[0104]
[0105] in, V o This is the DC-side output voltage. β s The duty cycle of the rectifier input voltage. Z _in (3) The input impedance corresponding to the third harmonic of the resonant network as seen from the rectifier end. To determine the input impedance corresponding to the fifth harmonic component of the resonant network from the rectifier end, U cd (3) is the third harmonic component in the rectifier input voltage. U cd (5) is the fifth harmonic component in the rectifier input voltage. n 1 is the inductance of the secondary main coil. L s With compensation inductance value L rs The ratio between them The third harmonic component in the input resonant current of the rectifier. The fifth harmonic component in the input resonant current of the rectifier.
[0106] Set the first compensation value in the controller. I d2 Divided by the second compensation value I q2 We obtain the intermediate variable g, and then calculate the inverse trigonometric function value of g to obtain the phase sampling value between the fundamental component of the current rectifier input voltage and the fundamental component of the rectifier input current. φ The phase between the current rectifier input voltage and current can be obtained according to the following formula: Figure 5 As shown.
[0107]
[0108] in, This is the value after the first compensation. The value after the second compensation is given. The above formula is the phase calculation formula, which is also... Figure 2 and Figure 5 The phase calculation formula mentioned in the text.
[0109] Phase reference value command φ ref Compared with the phase sampling value obtained in the previous step φ The difference is calculated and fed into the compensation controller. The output value of the compensation controller is the carrier comparison value A. Then, carrier comparison value B is obtained from carrier comparison value A. Carrier comparison values A and B are compared with a triangular carrier: when the triangular carrier equals value A, the drive pulse is set high; when the triangular carrier equals value B, it is set to zero, thereby generating the power transistor in the active rectifier. Q The drive signal is 1. Based on the dead time, the power transistor... Q 2 and Q 1. Complementary drive signals can be used to obtain power transistors. Q 2. Drive pulse. Power transistor. Q The drive signal of 3 is transmitted through the Q 1 drive signal delay β s T The time can be obtained. Based on the dead time, the power transistor... Q 4 and Q 3. Complementary drive signals can be used to obtain power transistors. Q 4. Drive pulse signal.
[0110] To verify the correctness of the proposed phase-locked loop method, a simulation model and an experimental prototype were built. The experimental prototype had a power of 1kW, and the parameters used for simulation and experiment are listed in Table 1 below. Figure 6 The steady-state simulation waveforms of the rectifier input voltage and current of the system are shown when the phase-locked loop is stable. Figure 7 It demonstrates that when the phase-locked loop is stable, I d1 Steady-state simulation waveform. Figure 8 When the phase-locked loop is stable, I q1 Steady-state simulation waveform. Figure 9 The steady-state experimental waveforms of the rectifier input voltage and current after applying the method of this invention are shown. Simulation and experiments demonstrate the practicality and stability of this method.
[0111] Table 1 Experimental and Simulation Parameters
[0112]
[0113] This invention proposes a phase-locked loop system for active rectification in wireless power transmission systems, such as... Figure 10 As shown, it includes:
[0114] The first parameter acquisition module is used to import the rectifier input current value into the signal conditioning circuit, acquire the first component and the second component containing phase information, perform analog-to-digital conversion on the first component to obtain the third component, and perform analog-to-digital conversion on the second component to obtain the fourth component.
[0115] The second parameter acquisition module is used to obtain the first compensated value based on the third component, the rectifier output voltage, and the resonant network parameters; and to obtain the second compensated value based on the second component, the rectifier output voltage, and the resonant network parameters.
[0116] The third parameter acquisition module is used to obtain the phase sampling value between the fundamental component of the current rectifier input voltage and the fundamental component of the rectifier input current based on the first compensated value and the second compensated value.
[0117] The drive signal acquisition module is used to obtain the phase difference based on the phase reference value command and the phase sampling value, input the phase difference into the compensation controller of the controller to output the carrier comparison value, and obtain the drive signal of the power tube in the rectifier based on the carrier comparison value and the triangular carrier to realize the phase lock of active rectification.
[0118] This invention proposes a phase-locked loop (PLL) method for active rectification in wireless power transmission systems, solving the technical problems of unreliable PLL and complex hardware circuitry in existing full-bridge active rectification technologies. The PLL method of this invention can be used in common topologies such as bilateral LCC compensation, bilateral LCL compensation, and series resonant compensation, and the active rectification can employ a half-bridge or full-bridge topology. The proposed PLL method first detects the rectifier input resonant current, and then the detected current is fed into two signal conditioning circuits. In one of the signal conditioning circuits, the input current sampling signal is directly coupled to the power transistor of the upper half-bridge arm of the full-bridge circuit. Q After multiplying the driving pulses, the resulting signal is filtered by a low-pass filter circuit to obtain the intermediate variable for phase-locked control. I d In another signal conditioning circuit, the input current sampling signal is compared with the power transistor of the upper half-bridge arm of the full-bridge circuit. Q The drive pulses are multiplied after a 1 / 4 working cycle delay, and the resulting signal is filtered by a low-pass filter circuit to obtain the intermediate variable for phase-locked control. I qThis invention proposes a phase-locked loop (PLL) method for active rectification in wireless power transmission systems, which has the following advantages: 1) The PLL method proposed in this invention does not rely on zero-crossing detection of the resonant current, avoiding the instability problem caused by zero-crossing detection of the resonant current in traditional synchronization methods. Using the PLL technology in this invention can improve the reliability and security of active rectification. 2) The proposed PLL method can be applied to various resonant topologies and has strong scalability. 3) Compared with PLL methods that detect the active and reactive power input of the rectifier, the proposed PLL method has the advantage of simpler hardware circuitry.
[0119] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A phase-locked loop method for active rectification in a wireless power transmission system, characterized in that, Includes the following steps: The rectifier input current value is fed into the signal conditioning circuit to obtain the first and second components containing phase information. The first component is converted from analog to digital to obtain the third component, and the second component is converted from analog to digital to obtain the fourth component. The value after the first compensation is obtained based on the third component, the rectifier output voltage, and the resonant network parameters; The second compensated value is obtained based on the second component, the rectifier output voltage, and the resonant network parameters; The phase sampling value between the fundamental component of the current rectifier input voltage and the fundamental component of the rectifier input current is obtained based on the first and second compensated values. The phase difference is obtained based on the phase reference value command and the phase sampling value. The phase difference is input into the compensation controller of the controller to output the carrier comparison value. The drive signal of the power tube in the rectifier is obtained based on the carrier comparison value and the triangular carrier, so as to realize the phase lock of active rectification. The driving pulse of the upper bridge arm is multiplied with the sampled rectifier input current. The multiplication is achieved by a multiplication circuit. The output value of the multiplication circuit is sent to a low-pass filter circuit to obtain the first component. The sampled rectifier input current is multiplied by the drive pulse delayed by T / 4 cycles, and the output value of the multiplier circuit is sent to the low-pass filter circuit to obtain the second component; Third component I d The expression is as follows: Fourth component The expression is as follows: in, Input resonant current to the rectifier. For power transistors Q A square wave of driving pulse voltage of 1. The system's operating cycle is given by t, where t is a time variable. Input resonant current to the rectifier. For power transistors Q The square wave signal obtained after delaying the driving pulse of 1 by T / 4 cycles.
2. The phase-locked loop method for active rectification in a wireless power transmission system according to claim 1, characterized in that, The controller compensates for the influence of harmonic components in the rectifier input current on the first and second components.
3. The phase-locked loop method for active rectification in a wireless power transmission system according to claim 1, characterized in that, The value after first compensation The expression is as follows: in, The third component, The duty cycle of the rectifier input voltage. To determine the input impedance corresponding to the third harmonic of the resonant network from the rectifier end, This refers to the third harmonic component in the rectifier input voltage. The fifth harmonic component in the rectifier input voltage. The third harmonic component in the input resonant current of the rectifier. The fifth harmonic component in the input resonant current of the rectifier. For power transistors Q 1 is a square wave of driving pulse voltage.
4. The phase-locked loop method for active rectification in a wireless power transmission system according to claim 3, characterized in that, Second compensation value The expression is as follows: in, The fourth component, This represents the duty cycle of the rectifier input voltage.
5. The phase-locked loop method for active rectification in a wireless power transmission system according to claim 4, characterized in that, Third harmonic component in the rectifier input resonant current The expression is as follows: The fifth harmonic component in the rectifier input resonant current The expression is as follows: in, This is the DC-side output voltage. This refers to the third harmonic component in the rectifier input voltage. To determine the input impedance corresponding to the fifth harmonic component of the resonant network from the rectifier end, Secondary main coil inductance L s With compensation inductance value The ratio between them This is the system's operating angular frequency.
6. The phase-locked loop method for active rectification in a wireless power transmission system according to claim 1, characterized in that, Phase sampling value between the fundamental component of the rectifier input voltage and the fundamental component of the rectifier input current φ The expression is as follows: in, This is the value after the first compensation. This is the value after the second compensation.
7. The phase-locked loop method for active rectification in a wireless power transmission system according to claim 1, characterized in that, The method for obtaining the drive signal of the power transistor in the rectifier based on the carrier comparison value and the triangular carrier is as follows: Based on carrier comparison value A, carrier comparison value B is obtained. When carrier comparison value B equals the triangular carrier value, the drive pulse is set to zero, generating the power transistor in the active rectifier. Q 1 is the drive signal; power transistor Q 2 with power transistor Q The drive signals of 1 are complementary, resulting in the power transistor. Q 2. Drive signal; For power transistors Q 1 drive signal delay β s T Time, to obtain the power transistor Q 3. Drive signal; power transistor Q 4 with power transistors Q The drive signals of 3 are complementary, resulting in the power transistor. Q 4. Drive signal.
8. A phase-locked loop system for active rectification in a wireless power transmission system, characterized in that, The phase-locked loop method according to any one of claims 1 to 7 includes: The first parameter acquisition module is used to import the rectifier input current value into the signal conditioning circuit, acquire the first component and the second component containing phase information, perform analog-to-digital conversion on the first component to obtain the third component, and perform analog-to-digital conversion on the second component to obtain the fourth component. The second parameter acquisition module is used to obtain the first compensated value based on the third component, the rectifier output voltage, and the resonant network parameters; and to obtain the second compensated value based on the second component, the rectifier output voltage, and the resonant network parameters. The third parameter acquisition module is used to obtain the phase sampling value between the fundamental component of the current rectifier input voltage and the fundamental component of the rectifier input current based on the first compensated value and the second compensated value. The drive signal acquisition module is used to obtain the phase difference based on the phase reference value command and the phase sampling value, input the phase difference into the compensation controller of the controller to output the carrier comparison value, and obtain the drive signal of the power tube in the rectifier based on the carrier comparison value and the triangular carrier to realize the phase lock of active rectification.